TWI842945B - Photo-detecting apparatus with subpixels - Google Patents

Abstract

A photo-detecting apparatus is provided. The photo-detecting apparatus includes at least one pixel, and each pixel includes N subpixels, wherein each of the subpixels comprises a detection region, two first conductive contacts, wherein the detection region is between the two first conductive contacts, wherein N is a positive integer and is ≥2.

Description

Light detection device with sub-pixels

The present disclosure relates to detecting light using a photodiode.

Photodetectors can be used to detect optical signals and convert them into electrical signals that can be further processed by another circuit. Photodetectors can be used in consumer electronics, image sensors, data communications, time-of-flight (TOF) or imaging sensors, medical devices, and many other suitable applications. However, when photodetectors are applied to these products in single or array configurations, leakage current, dark current, electrical/optical crosstalk, and power consumption can degrade performance.

According to an embodiment of the present disclosure, a light detection device is provided. The light detection device includes a semiconductor substrate. A first germanium-based light absorbing material is supported by the semiconductor substrate and is configured to absorb a first optical signal having a first wavelength greater than 800 nanometers. A first metal wire is electrically coupled to a first region of the first germanium-based light absorbing material. A second metal wire is electrically coupled to a second region of the first germanium-based light absorbing material. The first region is undoped or doped with a first type of dopant. The second region is doped with a second type of dopant. The first metal wire is configured to control the amount of a first type of photo-generated carriers generated inside the first germanium-based light absorbing material to be collected by the second region.

According to an embodiment of the present disclosure, a method for optical detection is provided. The method for optical detection includes: Sending an optical signal modulated by a first modulation signal, wherein the optical signal is modulated by the first modulation signal at one or more predetermined phases in multiple time frames. The reflected optical signal is received by a photodetector. The reflected optical signal is demodulated by one or more demodulation signals, wherein the one or more demodulation signals are signals with one or more predetermined phases in multiple time frames. At least one voltage signal is output on a capacitor.

2。 According to an embodiment of the present disclosure, a light detection device is provided. The light detection device includes at least one pixel, each pixel includes N sub-pixels, wherein each sub-pixel includes a detection region and two first conductive contacts, wherein the detection region is located between the two first conductive contacts, wherein N is a positive integer and

2.

2，以及第一像素和第二像素之間的隔離區域。 According to an embodiment of the present disclosure, a light detection device is provided. The light detection device includes a first pixel and a second pixel adjacent to the first pixel, wherein each of the first pixel and the second pixel includes N detection regions, 2N first conductive contacts, each of which is coupled to one of the detection regions, and 2N second conductive contacts, each of which is coupled to one of the detection regions, wherein N is a positive integer and

2, and an isolation region between the first pixel and the second pixel.

2。 According to an embodiment of the present disclosure, a light detection device is provided. The light detection device includes a light detection device, the light detection device includes a pixel, and the pixel includes N sub-pixels, wherein each sub-pixel includes a detection area and two switches, wherein the detection area is between the two switches, wherein N is a positive integer and

2.

2。 According to an embodiment of the present disclosure, an imaging system is provided. The imaging system includes an emitter unit capable of emitting light, and a receiver unit including an image sensor, the image sensor including: a light detection device including: a plurality of pixels, wherein each pixel includes: N sub-pixels, wherein each sub-pixel includes a detection region and two first conductive contacts, wherein the detection region is between the two first conductive contacts, and the detection region is configured to absorb photons having a certain wavelength and generate photocarriers from the absorbed photons; wherein N is a positive integer and

2.

Among other advantages and benefits of the embodiments disclosed herein, these embodiments provide a light detection device capable of effectively absorbing at least but not limited to near infrared light (NIR) or short wave infrared light (SWIR). In some embodiments, the photodetection device provides high demodulation contrast, low leakage current, low dark current, low power consumption, low electrical/optical crosstalk and/or an architecture for chip size miniaturization. In some embodiments, the light detection device is capable of processing incident optical signals with multiple wavelengths, including different modulation schemes and/or time-division functions. In addition, the light detection device can be used for time-of-flight (ToF) applications, which can operate at wavelengths longer than visible light wavelengths (e.g., near infrared and short wave infrared ranges). Component/material implementers can design/fabricate 100% germanium or an alloy (e.g., germanium-silicon) with a predetermined percentage (e.g., greater than 80% germanium) of germanium, which can be intrinsic (i.e., pure semiconductor material) or extrinsic, to act as a light absorbing material to absorb light of the above wavelengths.

These and other objects of the present disclosure will become apparent to those of ordinary skill in the art after reading the following detailed description of alternative embodiments illustrated in the various accompanying drawings.

These and other objects of the present disclosure will no doubt become apparent to those of ordinary skill in the art after reading the following detailed description of the preferred embodiments illustrated in the various accompanying drawings and illustrations.

100a: Light detection equipment

100b: Optical detection equipment

100c: Optical detection equipment

100d: Light detection equipment

100e: Optical detection equipment

100f: Light detection equipment

101a: mixed area

101b: mixed area

102: Light absorbing material

102s: Surface

103a: Area (mixed area)

103b: Doped area

104:Semiconductor substrate

105a: Undoped area

105b: Undoped area

106a: Control metal wire

106b: Control metal wire

108a: Read the metal wire

108b: Reading metal wire

110a: Capacitor

110b:Capacitor

200a: Light detection equipment

200b: Optical detection equipment

200c: Optical detection equipment

200d: Light detection equipment

200e: Optical detection equipment

200f: Light detection equipment

200g: Optical detection equipment

200h: Light detection equipment

201a: N-type region

201b: N-type region

202s: Surface

203a: P-type region

203b: P-type region

204v:Through Silicon Via

206a: Control metal wire

206b: Control metal wire

207a: N-type region

207b: N-type region

208a: Reading the metal wire

208b: Reading metal wire

300a: Light detection equipment

300b: Optical detection equipment

301a: N-type region

301b: N-type region

302: Light absorbing material

302s: Surface

302ss: Surface

303a: P-type region

303b: P-type region

304:Semiconductor substrate

306a: Control metal wire

306b: Control metal wire

308a: Reading metal wire

308b: Reading metal wire

309a: Empty area

309b: Empty area

312: Dielectric layer

314v:Through Silicon Via

314u:Through Silicon Via

400a: Light detection equipment

400b: Optical detection equipment

400c: Light detection equipment

400d: Light detection equipment

401a: N-type region

401b: N-type region

402: Light absorbing material

402s: Surface

403a: P-type region

403b: P-type region

404:Semiconductor substrate

406a: Control metal wire

406b: Control metal wire

408a: Read the metal wire

408b: Read out metal wire

411a: N well

411b: N well

451a:P well

451b:P well

500a: Light detection equipment

501a: N-type region

501b: N-type region

502: Light absorbing material

502s: Surface

503a: P-type region

503b: P-type region

504:Semiconductor substrate

506a: Control metal wire

506b: Control metal wire

508a: Reading metal wire

508b: Read out metal wire

513a: Silicide

513b: Silicide

514: Passivation layer

515a: Silicide

515b: Silicide

600a: Light detection equipment

600b: Optical detection equipment

600c: Optical detection equipment

601a: N-type region

601b: N-type region

602: Light absorbing material

602s: Surface

602ss:Surface

603a: P-type region

603b: P-type region

604:Semiconductor substrate

604v:Through Silicon Via

606a: Control metal wire

606b: Control metal wire

608a: Reading metal wire

608b: Reading metal wire

617: N-type region

619: P-type region

700a: Light detection equipment

700b: Optical detection equipment

700c: Optical detection equipment

700d: Light detection equipment

701a: N-type region

701b: N-type region

702: Light absorbing material

702s: Surface

703a: P-type region

703b: P-type region

704:Semiconductor substrate

706a: Control metal wire

706b: Control metal wire

708a: Reading metal wire

708b: Read out metal wire

716a:Metal

716b:Metal

716ad: Empty area

716bd: Empty area

716ae: Polarized dielectric layer

716be: Polarized dielectric layer

718a:Metal

718b:Metal

718ad: Empty area

718bd: Empty area

718ae: Polarized dielectric layer

718be:Polarized dielectric layer

721:Metal

721d: Empty area

721e: Polarized dielectric layer

723a:Metal

723b:Metal

725a: Polarized dielectric layer

725b: Polarized dielectric layer

800a: Optical detection equipment

800b: Optical detection equipment

801a: N-type region

801b: N-type region

802: Light absorbing material

802s: Surface

803a: P-type region

803b: P-type region

804:Semiconductor substrate

806a: Control metal wire

806b: Control metal wire

808a: Reading metal wire

808b: Reading metal wire

829: Ion treatment area

831a: Ion treatment area

831b: Ion treatment area

833a: Ion treatment area

833b: Ion treatment area

900a: Light detection equipment

900b: Optical detection equipment

900c: Optical detection equipment

900d: Light detection equipment

900e: Optical detection equipment

901a: N-type region

901b: N-type region

902: Light absorbing material

902s: Surface

903a: P-type region

903b: P-type region

904:Semiconductor substrate

906a: Control metal wire

906b: Control metal wire

908a: Read the metal wire

908b: Read out the metal wire

924: Isolation area

924a: Isolation area

924b: Groove isolation area

1000a: Light detection equipment

1000b: Optical detection equipment

1000c: Optical detection equipment

1000d: Light detection equipment

1001a: N-type region

1001b: N-type region

1002: Light absorbing material

1002s: Surface

1002ss:Surface

1003a: P-type region

1003b: P-type region

1004:Semiconductor substrate

1005a: Undoped area

1005b: Undoped area

1006a: Control metal wire

1006b: Control metal wire

1008a: Read the metal wire

1008b: Read out metal wire

1010a:Capacitor

1010b:Capacitor

1011a: N well

1011b: N well

1013a: Silicide

1013b: Silicide

1014: Passivation layer

1015a: Silicide

1015b: Silicide

1019: P-type region

1021: Metal

1024: Isolation area

1100a: Light detection equipment

1100b: Optical detection equipment

1100c: Optical detection equipment

1100d: Optical detection equipment

1100e: Optical detection equipment

1101a: N-type region

1101b: N-type region

1102: Light absorbing material

1103a: P-type region

1103b: P-type region

1106a: Control metal wire

1106b: Control metal wire

1108a: Read out metal wire

1108b: Read out metal wire

1200a: Light detection equipment (pixel array)

1200b: Optical detection equipment

12021: pixels

12022: pixels

12023: pixels

12024: pixels

1300a: Light detection equipment

1302: Pixel array

1302a: first pixel array

1302b: Second pixel array

1304: Laser diode driver

1306: Laser diode

1308:Timer driver

13081:Timer driver

13082:Timer driver

13083:Timer driver

1310: Target object

1401: Steps

1402: Steps

1403: Steps

1404: Steps

1501: Base

1502: Light absorbing material

1505: Electrode (N+ terminal)

1506: Electrode (P+ terminal)

1507: Absorption area

1508: Optical opening

1511: Optical signal

1512: Optical signal

1515: Electrode (N+ terminal)

1516:P+ terminal

1518: Absorption area

1516:Electrode

1525: N+ terminal

1526:P+ terminal

1527: Insulation doped trap

1535: N+ terminal

1536:P+ terminal

1545: Isolation zone

1600: pixels

1600’: Pixels

1600a: sub-pixel

1600b: sub-pixel

1600c: Sub-pixel

1600d: Sub-pixel

1610: Absorption area

1611a: First doping region

1611b: First doping region

1612a: Second doping area

1612b: Second doping area

1613: Detection area

1613a: Reverse doping region

1613b: Reverse doping region

1614: The third mixed area

1615: The fourth mixed area

1616a: First side

1616b: First side

1617a: Second side

1617b: Second side

1620: Base

1621: Upper surface

1622: Bottom

1631a: First conductive contact

1631b: First conductive contact

1632a: Second conductive contact

1632b: Second conductive contact

1633a: First dielectric layer

1633b: Second dielectric layer

1640: Barrier layer

1650: Isolation area

1660: Shading layer

1661: Open mouth

1671a: First readout circuit

1671b: Second readout circuit

1672a: First control signal

1672b: Second control signal

1673a: First public readout circuit

1673b: Second public readout circuit

1674: Public control signal

1674a: First public control signal

1674b: Second public control signal

1700: pixels

1710: Absorption area

1711a: First doping region

1711b: First doping region

1712a: Second doping area

1712b: Second doping area

1713: Detection area

1725: Isolation area

1733: Dielectric layer

1735: Isolation area

1731a: First conductive contact

1731b: First conductive contact

1732a: Second conductive contact

1732b: Second conductive contact

1740: Barrier layer

1760: Short circuit structure

1765: First well region

1766: Second well region

1767: Conductive contact

1768: Conductive contact

1771a: First readout circuit

1771b: Second readout circuit

1772a: First control signal

1772b: Second control signal

1790: Switch

1791: Control area

1792: Read out area

AR: Absorption area

AR1: Absorption area

AR2: Absorption area

AR3: Absorption area

AR4: Absorption area

CLK1: timer signal

CLK2: timer signal

CLK3: timer signal

C1: endpoint

C2: Endpoint

C3: Endpoint

C4: Endpoint

ca1: bias voltage

ca2: bias voltage

ca3: bias voltage

cs1: control signal

cs2: control signal

D1: Horizontal direction

d1: depth

d2: depth

IL: Optical signal

M1: endpoint

M2: endpoint

M3: Endpoint

M4: Endpoint

TL: Transmitted light

v1: voltage

vb1: bias voltage

vb2: bias

vb3: bias

WD: Optical opening

w1: width

w2: width

The foregoing aspects of the present application and many of the attendant advantages will become more readily understood by reference to the following detailed description when taken in conjunction with the accompanying drawings, wherein:

Figures 1A-1F show cross-sectional views of light detection devices according to some embodiments.

Figures 2A-2H show cross-sectional views of a light detection device having a body depletion mode according to some embodiments.

3A-3B illustrate cross-sectional views of a light detection device having a gated body depletion mode according to some embodiments.

4A-4D illustrate cross-sectional views of photodetection devices with lower leakage current and lower dark current according to some embodiments.

FIG5 shows a cross-sectional view of a light detection device having a passivation layer according to some embodiments.

6A-6C illustrate cross-sectional views of a light detection device with enhanced charge transfer speed according to some embodiments.

7A-7B illustrate cross-sectional views of a light detection device having a surface depletion mode according to some embodiments.

Figures 7C-7D show plan views of light detection devices with surface depletion modes according to some embodiments.

FIG8A shows a cross-sectional view of a light detection device with surface ion implantation according to some embodiments.

FIG8B shows a plan view of a light detection device with surface ion implantation according to some embodiments.

FIG9A shows a cross-sectional view of a light detection device with inter-pixel isolation according to some embodiments.

FIG9B shows a plan view of a light detection device with inter-pixel isolation according to some embodiments.

Figures 9C-9E show cross-sectional views of a light detection device with inter-pixel isolation according to some embodiments.

Figures 10A-10D show cross-sectional views of light detection devices according to some embodiments.

Figures 11A-11E show plan views of a wafer-scale miniaturized light detection device according to some embodiments.

Figures 12A-12B show plan views of array configurations of light detection devices according to some embodiments.

Figures 13A-13E show block diagrams and timing diagrams of a light detection device using a modulation scheme with phase variation according to some embodiments.

FIG. 14 illustrates a process for using a light detection device that uses a modulation scheme with phase variation according to some embodiments.

FIG. 15A shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 15B shows a plan view of a light detection device according to some embodiments.

FIG. 15C shows a cross-sectional view of a light detection device according to some embodiments.

Figures 15D-15E show plan views of light detection devices according to some embodiments.

FIG. 16A shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 16B shows a top view of a light detection device according to some embodiments.

FIG. 16C shows a top view of a light detection device according to some embodiments.

FIG. 16D shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 16E shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 16F shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16G shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16H shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16I shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 16J shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16K shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16L shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16M shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16N shows a cross-sectional view of a light detection device according to some embodiments.

Figure 16O shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 16P shows a top view of a light detection device according to some embodiments.

FIG. 16Q shows a cross-sectional view of a sub-pixel in the light detection device shown in FIG. 16P .

FIG. 17A shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 17B shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 17C shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 17D shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 17E shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 17F shows a cross-sectional view of a light detection device according to some embodiments.

Figure 17G shows a cross-sectional view of a light detection device according to some embodiments.

Figure 17H shows a cross-sectional view of a light detection device according to some embodiments.

Figure 17I shows a cross-sectional view of a light detection device according to some embodiments.

FIG. 17J shows a cross-sectional view of a light detection device according to some embodiments.

Figure 17K shows a top view of a light detection device according to some embodiments.

FIG. 17L shows a top view of a light detection device according to some embodiments.

Figure 17M shows a top view of a light detection device according to some embodiments.

FIG. 17N shows a schematic diagram of the cross-sectional structure of the control area in three different embodiments of the present disclosure.

FIG18 is a block diagram of an example embodiment of an imaging system.

FIG19 shows a block diagram of an example receiver unit or controller.

1A shows a cross-sectional view of a light detection device according to some embodiments. The light detection device 100a includes a germanium-based light absorbing material 102 supported by a semiconductor substrate 104. In one embodiment, the semiconductor substrate 104 is made of silicon, silicon germanium, germanium, or a III-V compound. The germanium-based light absorbing material 102 herein refers to intrinsic germanium (100% germanium) or an alloy of an element including germanium, such as a silicon germanium alloy, with a germanium concentration ranging from 1% to 99%. In some embodiments, the germanium-based light absorbing material 102 can be grown using blanket epitaxy, selective epitaxy, or other applicable techniques. In FIG. 1A , the germanium-based light absorbing material 102 is embedded in the semiconductor substrate 104 , and in alternative embodiments, the germanium-based light absorbing material 102 may be partially embedded in the semiconductor substrate 104 , or may be located on the semiconductor substrate 104 .

The light detection device 100a includes a control metal wire 106a and a readout metal wire 108a. The control metal wire 106a and the readout metal wire 108a are both electrically coupled to the surface 102s of the germanium-based light absorbing material 102. In this embodiment, the control metal wire 106a is electrically coupled to an undoped region 105a on the surface 102s, wherein the undoped region 105a has no dopant. The readout metal wire 108a is electrically coupled to a doped region 101a on the surface 102s, wherein the doped region 101a has a dopant.

Note that the germanium-based light absorbing material 102 can be formed as intrinsic or extrinsic (e.g., lightly doped P-type or lightly doped N-type). Due to the defect characteristics of the germanium material, the germanium-based light absorbing material 102 can still be lightly doped P-type even without introducing an additional doping process. Therefore, the undoped region 105a can also be lightly doped P-type. The doped region 101a can be doped with a P-type dopant or an N-type dopant, depending on the type of photocarriers (i.e., holes or electrons) to be collected. In some embodiments, the doped region 101a can be doped by thermal diffusion, ion implantation, or any other doping process.

The control metal wire 106a is controlled by the control signal cs1 and is used to control the movement direction of the electrons or holes generated by the absorbed photons. Assume that the doped region 101a is N-type and the control signal cs1 is in logic 1. An electric field is generated from the control metal wire 106a to the germanium-based light absorbing material 102. The electrons will move toward the control metal wire 106a and be collected by the doped region 101a. On the contrary, if the doped region 101a is P-type, the holes will be collected. Alternatively, assuming that the doped region 101a is N-type when the control signal cs1 is in logic 0, a different electric field is generated from the control metal wire 106a to the germanium-based light absorbing material 102. Electrons do not move toward the control metal wire 106a and therefore cannot be collected by the doped region 101a. On the contrary, if the doped region 101a is P-type, holes will not be collected.

Using the structure shown in FIG1A , the optical signal IL reflected by the target object (not shown in FIG1A ) and entering through the optical opening (window) WD can be absorbed by the germanium-based light absorbing material 102 and generate electron-hole pairs, so that the electrons or holes (depending on whether the doped region 101a is N-type or P-type) move to the capacitor 110a according to the assertion of the control signal cs1 and are stored in the capacitor 110a. The absorption region AR is a virtual region that receives the optical signal IL entering through the optical opening WD. Due to the distance between the light detection device 100a and the target object (not shown in FIG1A ), the optical signal IL has a phase delay relative to the incident light emitted by the emitter (not shown in FIG1A ). When the transmitted light is modulated by the modulation signal and the electron-hole pairs are demodulated by the demodulation signal through the control metal wire 106a, the electrons or holes stored in the capacitor 110a will change according to the distance. Therefore, the light detection device 100a can obtain distance information based on the voltage v1 on the capacitor 110a.

The embodiments of FIG. 1A are one-tap structures because they use only one control metal line 106a and one read metal line 108a to obtain distance information. The disclosed embodiments may also use two or more control lines or read lines and various injections to obtain distance information, which will be described in detail below.

FIG1B shows a cross-sectional view of a light detection device according to some embodiments. Compared to the embodiment of FIG1A , the light detection device 100b of FIG1B uses two control metal wires 106a, 106b to control the movement of electrons or holes generated by photons absorbed in the germanium-based light absorbing material 102. This structure is called a two-tap structure. The light detection device 100b includes control metal wires 106a, 106b and readout metal wires 108a, 108b. The control metal wires 106a, 106b and the readout metal wires 108a, 108b are electrically coupled to the surface 102s of the germanium-based light absorbing material 102. In this embodiment, control metal lines 106a, 106b are electrically coupled to undoped regions 105a, 105b on surface 102s, respectively, where undoped regions 105a, 105c are regions without dopants; and read metal lines 108a, 108b are electrically coupled to doped regions 101a, 101b on surface 102s, respectively, where doped regions 101a, 101b are regions with dopants. Doped regions 101a, 101b may be doped with P-type dopants or N-type dopants.

The control metal wires 106a and 106b are controlled by control signals cs1 and cs2, respectively, to control the movement direction of electrons or holes generated by absorbed photons. In some embodiments, the control signals cs1 and cs2 are differential voltage signals. In some embodiments, one of the control signals cs1 and cs2 is a constant voltage signal (e.g., 0.5V), and the other control signal is a time-varying voltage signal (e.g., a sinusoidal signal, a clock signal, or a pulse signal operating between 0V and 1V).

Assuming that the doped regions 101a and 101b are N-type, and the control signals cs1 and cs2 are timer signals with a phase difference of 180 degrees, when the control signal cs1 is logic 1 and the control signal cs2 is logic 0, the light detection device 100b generates an electric field from the control metal wire 106a to the germanium-based light absorbing material 102, and electrons will move toward the control metal wire 106a and then be collected by the doped region 101a. Similarly, when the control signal cs1 is at logic 0 and the control signal cs2 is at logic 1, the light detection device 100b generates an electric field from the control metal wire 106b to the germanium-based light absorbing material 102, and the electrons will move toward the control metal wire 106b and then be collected by the doped region 101b. On the contrary, if the doped regions 101a and 101b are P-type, the holes will be collected.

According to this double-tap structure, according to the assertions of the control signal cs1 and the control signal cs2, the optical signal IL reflected from the target object (not shown in FIG. 1B ) can be absorbed by the germanium-based light absorbing material 102 and generate electron-hole pairs, so that the electrons or holes (depending on whether the doped region 101a is N-type or P-type) move to the capacitor 110a or the capacitor 110b and are stored in the capacitor 110a or the capacitor 110b. Due to the distance between the light detection device 100b and the target object (not shown in FIG. 1B ), the optical signal IL has a phase delay relative to the incident light emitted by the emitter (not shown in FIG. 1B ). When the transmitted light is modulated by the modulation signal and the electron-hole pairs are demodulated by the demodulation signal through the control metal wires 106a and 106b, the electrons or holes stored in the capacitors 110a and 110b will change according to the distance. Therefore, the light detection device 100b can obtain distance information based on the voltage v1 on the capacitor 110a and the voltage v2 on the capacitor 110b. According to one embodiment, the distance information can be derived based on a calculation with the voltage v1 and the voltage v2 as input variables. For example, in a pulse flight time configuration, a voltage ratio related to the voltage v1 and the voltage v2 is used as an input variable. In another example, in a continuous time-of-flight configuration, in-phase and quadrature voltages associated with voltage v1 and voltage v2 are used as input variables.

The control metal line 106a in FIG. 1A and the control metal lines 106a, 106b in FIG. 1B are electrically coupled to the undoped region of the germanium-based light absorbing material 102. In other embodiments, as described below, certain structures and the control metal lines 106a, 106b are electrically coupled to the doped region.

FIG1C shows a cross-sectional view of a light detection device according to some embodiments. Similar to FIG1A , the light detection device 100c includes a control metal wire 106a and a readout metal wire 108a. The control metal wire 106a and the readout metal wire 108a are both electrically coupled to the surface 102s of the germanium-based light absorbing material 102. In this embodiment, the control metal wire 106a is electrically coupled to the doped region 103a on the surface 102s, wherein the doped region 103a is a region having a dopant; and the readout metal wire 108 is electrically coupled to the doped region 101a on the surface 102s, wherein the doped region 101a is also a region having a dopant. In this embodiment, region 101a and region 103a are doped with different types of dopants. For example, if region 101a is doped with an N-type dopant, region 103a will be doped with a P-type dopant, and vice versa.

The operation of the light detection device 100c is similar to the embodiment of FIG. 1A. The control metal wire 106a is used to control the moving direction of the electrons or holes generated by the absorbed photons according to the control signal cs1 so that the electrons or holes are collected by the doped region 101a. By controlling the control signal cs1 and reading the voltage v1 on the capacitor 110a, the light detection device 100c can obtain the distance information between the light detection device 100c and the target object (not shown in FIG. 1C).

1D shows a cross-sectional view of a light detection device according to some embodiments. The light detection device 100b includes control metal wires 106a, 106b and read metal wires 108a, 108b. The control metal wires 106a, 106b and read metal wires 108a, 108b are electrically coupled to the surface 102s of the germanium-based light absorbing material 102. In this embodiment, the control metal wires 106a, 106b are electrically coupled to the doped regions 103a, 103b on the surface 102s, respectively, wherein the doped regions 103a, 103b are regions with dopants. Readout metal lines 108a, 108b are electrically coupled to doped regions 101a, 101b on surface 102s, respectively, where doped regions 101a, 101b are also doped regions. Regions 101a, 101b, 103a, 103b may be doped with a P-type dopant or an N-type dopant. In this embodiment, doped regions 101a, 101b are doped with the same type of dopant; and doped regions 103a, 103b are doped with the same type of dopant. However, the type of doped regions 101a, 101b is different from the type of doped regions 103a, 103b. For example, if doped regions 101a, 101b are doped to N-type, doped regions 103a, 103b will be doped to P-type, and vice versa.

The operation of the light detection device 100d is similar to the embodiment of FIG. 1B. The control metal wires 106a and 106b are used to control the movement direction of the electrons or holes generated by the absorbed photons according to the control signals cs1 and cs2, so that the electrons or holes are stored in the capacitor 110a or the capacitor 110b. By controlling the control signals cs1 and cs2 and reading the voltages v1 and v2 on the capacitors 110a and 110b, the light detection device 100d can obtain the distance information between the light detection device 100d and the target object (not shown in FIG. 1D).

FIG. 1E shows a cross-sectional view of a light detection device according to some embodiments. The operation of the device is similar to that of FIG. 1D, wherein the device is capable of obtaining distance information between the light detection device 100d and a target object (not shown in FIG. 1E) by generating control signals cs1, cs2 and reading voltages v1, v2 on capacitors 110a, 110b. The difference from FIG. 1D is that the readout metal wires 108a, 108b and the doped regions 101a, 101b are arranged at a surface 102ss opposite to the surface 102s. Because the control metal wires 106a, 106b and the readout metal wires 108a, 108b are arranged in a vertical direction, the horizontal area of the light detection device 100e can be reduced accordingly.

FIG. 1F shows a cross-sectional view of a light detection device according to some embodiments. Compared to FIG. 1E, the embodiment in FIG. 1F also arranges doped regions 101a, 101b at the surface 102s opposite to the surface 102s, but the readout metal lines 108a, 108b extend toward the surface 102s instead of toward the semiconductor substrate 104. This arrangement can simplify the manufacturing process.

In some embodiments, such as the embodiments shown in FIGS. 1A to 1F and the embodiments described below, the control metal lines 106a, 106b and the surface 102s can be made into a metal-semiconductor junction (MS junction) with a Schottky barrier or a metal-insulator-semiconductor capacitor (MIS capacitor) by introducing an oxide or a high-k dielectric material as an insulator between the metal and the semiconductor.

As shown in the embodiments shown in FIGS. 1A to 1F and the embodiments described below, the germanium-based light absorbing material 102 is formed into a rectangular shape from its cross-sectional view, however, in some embodiments, the germanium-based light absorbing material 102 may be formed into an inverted trapezoid or other pattern from its cross-sectional view.

The light detection devices shown in the present disclosure can be used for time-of-flight (ToF) applications, which can operate at longer wavelengths (e.g., near infrared or SWIR ranges) than visible light wavelengths. The wavelengths can be above 800 nm, such as 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm, or 1550 nm. On the other hand, the device/material implementer () can design/manufacture 100% germanium or an alloy (e.g., germanium silicon) with a predetermined percentage (e.g., greater than 80% germanium), which can be intrinsic or extrinsic, as a light absorbing material to absorb light of the above wavelengths.

Although the embodiments herein show that the light detection device absorbs the optical signal IL from the back side, in some embodiments, the light detection device may be designed to absorb the optical signal IL from the front side, for example, by creating an optical opening WD between the two control metal wires 106a, 106b.

The embodiments shown in FIG. 1A to FIG. 1F include a single photodetector, which can be used as a unit and applied to each pixel of a pixel array. The following description is based on an alternative embodiment of the single-tap or double-tap structure disclosed in FIG. 1F to FIG. 1F. In the following description, one or two embodiments from FIG. 1A to FIG. 1F can be selected as representative embodiments. A person skilled in the art can change, modify or combine the structures disclosed herein, such as replacing the double-tap structure with a single-tap structure.

2A shows a cross-sectional view of a light detection device with a matrix depletion mode according to some embodiments. The light detection device 200a includes control metal wires 206a, 206b and read metal wires 208a, 208b. The control metal wires 206a, 206b and the read metal wires 208a, 208b are electrically coupled to the surface 202s of the germanium-based light absorbing material 202. The control metal wires 206a, 206b are electrically coupled to the P-type regions 203a, 203b on the surface 202s, respectively, and the read metal wires 208a, 208b are electrically coupled to the N-type regions 201a, 201b on the surface 202s, respectively. In some embodiments, the depth d1 of the P-type regions 203a, 203b extending from the surface 202s is deeper than the depth d2 of the N-type regions 201a, 201b, and the germanium-based light absorbing material 202 is slightly N-type. For the deeper P-type regions 203a, 203b, a larger depletion region is generated between the deeper P-type regions 203a, 203b and the N-type germanium-based light absorbing material 202, and when two different voltages are applied to the control metal wires 206a, 206b, electrons can be allowed to move to the N-type regions 201a, 201b, thereby increasing the quantum efficiency and demodulation contrast. In other aspects, the width w1 of the P-type regions 203a and 203b, the width w2 of the N-type regions 201a and 201b, the doping concentration of the P-type regions 203a and 203b, and/or the doping concentration of the N-type regions 201a and 201b are also parameters for adjusting the area of the depletion region.

In some embodiments, in order to completely deplete the body of the N-type germanium-based light absorbing material 202, the N-type regions 201a, 201b and/or the P-type regions 203a, 203b may be designed through their depth, width, or doping concentration. In addition, the thickness of the germanium-based light absorbing material 202 should be designed accordingly.

FIG2B shows a cross-sectional view of a light detection device having a matrix depletion mode according to some embodiments. The light detection device 200b can be designed to have shallower P-type regions 203a, 203b. In other words, the depth d1 of the P-type regions 203a, 203b extending from the surface 202s is shallower than the depth d2 of the N-type regions 201a, 201b. Applying shallower P-type regions 203a, 203b can reduce leakage current between the P-type regions 203a and 203b.

2C shows a cross-sectional view of a light detection device with a substrate depletion mode according to some embodiments. The structure of the light detection device 200c is similar to that of the light detection devices 200a and 200b. The photodetection device 200c applies a bias voltage vb1 on the semiconductor substrate 204. The bias voltage vb1 is applied to generate a reverse bias on the junction between the N-type germanium-based light absorbing material 202 and the P-type regions 203a and 203b. As a result, the depletion region below the P-type regions 203a and 203b can be expanded or even completely depleted. Since a larger depletion region is generated under the P-type regions 203a and 203b, when two different voltages are applied to the control metal wires 206a and 206b, electrons can be allowed to move to the N-type regions 201a and 201b, thereby increasing the quantum efficiency and demodulation contrast.

FIG2D shows a cross-sectional view of a light detection device with a matrix depletion mode according to some embodiments. Similar to the structure of the light detection devices 200a and 200b, the embodiment applies a bias voltage vb2 to the germanium-based light absorbing material 202 to control the depletion region inside the germanium-based light absorbing material 202. Specifically, the bias voltage vb2 is a reverse bias to the P-type regions 203a and 203b and the N-type germanium-based light absorbing material 202, so that the depletion region around the P-type regions 203a and 203b can be expanded or even completely depleted.

In order to generate an even larger depletion region inside the germanium-based light absorbing material 202, an embodiment shown in FIG. 2E is disclosed. The light detection device 200e includes N-type regions 207a, 207b on a surface. The surface is opposite to the surface 202s. Using the N-type regions 207a, 207b, a PN junction is formed, in which a depletion region between the P-type region 203a and the N-type region 207a, and a depletion region between the P-type region 203b and the N-type region 207b are generated. Therefore, when two different voltages are applied to the control metal wires 206a, 206b, an electric field is generated in the absorption region. Therefore, the depletion region/electric field can be controlled by the control signals cs1, cs2 to control the movement direction of electrons toward the N-type region 201a or the N-type region 201b.

FIG2F shows a cross-sectional view of a light detection device with a matrix depletion mode according to some embodiments. The light detection device 200f includes a wider N-type region 207, which is located below the P-type regions 203a, 203b. Similarly, the N-type region 207 can enhance the generation of depletion regions around the P-type regions 203a, 203b, and thus increase the quantum efficiency and demodulation contrast. Note that the width of the N-type region 207 is adjustable and the depicted width of the N-type region 207 in FIG2F is for reference only.

FIG. 2G and FIG. 2H illustrate alternative embodiments of methods for biasing the N-type region 207. FIG. 2G applies a through silicon via (TSV) 204v to bias the N-type region 207, and FIG. 2G applies a germanium through via 204v extending from the surface 202s to bias the N-type region 207.

2A to 2H show various embodiments using the body depletion mode, including designing the depth of the P-type regions 203a and 203b, applying bias voltages vb1 and vb2 to the semiconductor substrate 204 or the germanium-based light absorbing material 202, adding N-type regions 207, 207a, and 207b inside the germanium-based light absorbing material 202, etc. These methods generate depletion regions under or around the P-type regions 203a and 203b to control the movement of electrons generated from absorbed photons to the N-type region 201a or the N-type region 201b.

3A-3B show cross-sectional views of a light detection device with a gate-controlled body depletion mode according to some embodiments. In addition to the embodiments shown in FIGS. 2A-2H , FIGS. 3A-3B disclose a dielectric gate-controlled body depletion mode. The light detection device 300a includes control metal wires 306a, 306b and read metal wires 308a, 308b. The control metal wires 306a, 306b and the read metal wires 308a, 308b are electrically coupled to a surface 302s of a germanium-based light absorbing material 302. The control metal wires 306a, 306b are electrically coupled to P-type regions 303a, 303b on the surface 302s, respectively, and the read metal wires 308a, 308b are electrically coupled to N-type regions 301a, 301b on the surface 202s, respectively. The germanium-based light absorbing material 302 is slightly N-type. In addition, the light detection device 300a includes an N-type region 307 on the surface 302ss, a dielectric layer 312 formed between the germanium-based light absorbing material 302 and the semiconductor substrate 304, and a through silicon via (TSV) 314 (including through silicon vias 314v and 314u). In some embodiments, the dielectric layer 312 is arranged between the metal (through hole 314) and the semiconductor (germanium-based light absorbing material 302), which forms a structure similar to a metal oxide semiconductor. By forming the dielectric layer 312 between the N-type region 307 and the through hole 314, the through hole 314 can reduce or prevent the flow of electrons into the N-type region 307 to generate leakage current.

In some alternative embodiments, the dielectric layer 312 may not be a continuous layer across the entire semiconductor substrate 304, but may be patterned into different regions located below the N-type region 307. The dielectric layer 312 may be thin or have some predetermined thickness, including multiple or multiple layers of materials or alloys or compounds. For example, silicon dioxide, silicon nitride, high dielectric constant dielectric materials or combinations thereof.

FIG3B shows a cross-sectional view of a light detection device with a gate-controlled body depletion mode according to some embodiments. This embodiment does not have an N-type region 307 on the surface 302, but generates depletion regions 309a, 309b by body biases vb2 and vb3. Body bias vb2 and body bias vb3 can be applied together or separately to control the size of depletion regions 309a, 309b. The separately applied voltage of body bias vb2 and the separately applied voltage of body bias vb3 can be the same or different.

In FIG. 3A or FIG. 3B , these embodiments insert a dielectric layer 312 between the germanium-based light absorbing material 302 and the semiconductor substrate 304, and generate a depletion region (e.g., 309a, 309b in FIG. 3B ) under the P-type regions 303a, 303b according to control signals cs1, cs2 and body biases vb2, vb3, so as to control the electron movement direction inside the germanium-based light absorbing material 302. Due to the insertion of the dielectric layer 312, it can reduce or prevent electrons from flowing into the N-type region 307 (FIG. 3A) and the depletion regions 309a, 309b (FIG. 3B) through the silicon through hole 314 to generate leakage current (FIGs. 3A and 3B).

FIG4A shows a cross-sectional view of a photodetection device with low leakage current and low dark current according to some embodiments. The photodetection device 400a includes control metal wires 406a, 406b and read metal wires 408a, 408b. The control metal wires 406a, 406b and read metal wires 408a, 408b are electrically coupled to a surface 402s of a germanium-based light absorbing material 402. The control metal wires 406a, 406b are electrically coupled to P-type regions 403a, 403b on the surface 402s, respectively, and the read metal wires 408a, 408b are electrically coupled to N-type regions 401a, 401b on the surface 402s, respectively. The operation of the device in FIG4A is similar to the embodiments disclosed above. The embodiment of FIG. 4A adds N-wells 411a and 411b that completely surround the P-type regions 403a and 403b. This can have the effect of reducing the leakage current between the P-type regions 403a and 403b. In another embodiment, as shown in FIG. 4B, N-wells 411a and 411b can be added around the P-type regions 403a and 403b. This also has the effect of reducing the leakage current between the P-type regions 403a and 403b.

In addition to the embodiments shown in FIG. 4A and FIG. 4B , a P-well may be added. The embodiment of FIG. 4C adds P-wells 451a, 451b that completely surround the N-type regions 401a, 401b. This may have the effect of reducing the dark current that appears in the N-type regions 401a, 401b. In an alternative embodiment, as shown in FIG. 4D , P-wells 451a, 451b may be added partially around the N-type regions 401a, 401b. This also has the effect of reducing the dark current that appears in the N-type regions 401a, 401b.

The embodiments shown in FIGS. 4A-4D respectively apply N-well and P-well to reduce leakage current and dark current. A person skilled in the art may change or modify the patterns of N-wells 411a, 411b and/or P-wells 451a, 451b according to design requirements. For example, N-well 411a may be designed to completely surround P-type region 403a in an asymmetric manner (e.g., the left side width of N-well 411a is wider than the right side width of N-well 411a). Similarly, N-well 411b may also be designed to completely surround P-type region 403b in an asymmetric manner (e.g., the right side width of N-well 411b is wider than the left side width of N-well 411b). Similar or modified embodiments may also be applied to P-wells 451a, 451b.

5 shows a cross-sectional view of a light detection device with a passivation layer according to some embodiments. The light detection device 500a includes control metal wires 506a, 506b and read metal wires 508a, 508b. The control metal wires 506a, 506b and the read metal wires 508a, 508b are electrically coupled to a surface 502s of a germanium-based light absorbing material 502. The control metal wires 506a, 506b are electrically coupled to P-type regions 503a, 503b on the surface 502s, respectively, and the read metal wires 508a, 508b are electrically coupled to N-type regions 501a, 501b on the surface 502s, respectively. The embodiment of FIG. 5 adds a passivation layer 514 (e.g., amorphous silicon (a-Si), GeOx, _Al2O3 , silicon dioxide) on the surface _502s , adds a silicide (e.g., _NiSi2 , _CoSi2 ) 513a at the connection between the readout metal line 508a and the N-type region 501a, adds a silicide 513b at the connection between the readout metal line 508b and the N-type region 501b, adds a silicide 515a at the connection between the control metal line 506a and the P-type region 503a, and adds a silicide 515b at the connection between the control metal line 506b and the P-type region 503b.

According to this embodiment, forming a passivation layer 514 on the germanium-based light absorbing material 502 can terminate dangling bonds on the surface 502s, thereby reducing dark current. On the other hand, adding silicide (e.g., _NiSi2 , _CoSi2 ) can also reduce the contact or junction resistance between the metal and the semiconductor, which reduces the voltage drop and correspondingly reduces the power consumption.

FIG6A shows a cross-sectional view of a light detection device with an improved charge transfer speed according to some embodiments. The light detection device 600a includes control metal wires 606a, 606b and read metal wires 608a, 608b. The control metal wires 606a, 606b and the read metal wires 608a, 608b are electrically coupled to a surface 602s of a germanium-based light absorbing material 602. The control metal wires 606a, 606b are electrically coupled to P-type regions 603a, 603b on the surface 602s, respectively, and the read metal wires 608a, 608b are electrically coupled to N-type regions 601a, 601b on the surface 602s, respectively. The embodiment of FIG6A adds an N-type region 617 on the surface 602s and a P-type region 619 on the surface 602ss. The N-type region 617 and the P-type region 619 are formed substantially at the center of the germanium-based light absorbing material 602, which is the location where the optical signal IL can pass through. Since the N-type region 617 and the P-type region 619 are formed together as a PN junction, a built-in vertical electric field is established between the N-type region 617 and the P-type region 619, which can help separate electron-hole pairs generated by absorbed photons, wherein electrons tend to move toward the N-type region 617 and holes tend to move toward the P-type region 619. The N-type region 617 is operated to collect electrons, and the P-type region 619 is operated to collect holes. The electrons stored in the N-type region 617 can move to the N-type region 601a or the N-type region 601b according to the control signals cs1, cs2. It is worth noting that, depending on the operation of the light detection device 600a, the metal line 610 can be floating or biased by the bias ca1. In one embodiment, the doping concentration of the N-type regions 601a, 601b is higher than the doping concentration of the N-type region 617.

FIG. 6B shows a cross-sectional view of a light detection device with an improved charge transfer speed according to some embodiments. This embodiment is similar to the light detection device 600a. The difference is that the P-type region 619 can be biased through a silicon through hole 604v, wherein the holes collected in the P-type region 619 can be discharged through the silicon through hole 604v, and the silicon through hole 604v is biased by a bias voltage ca2 thereon.

FIG6C shows a cross-sectional view of a light detection device with an improved charge transfer speed according to some embodiments. The embodiment of FIG6C is similar to the light detection device 600b. The difference is that a U-shaped or well-shaped P-type region 619 is formed below and around the germanium-based light absorbing material 602. In addition, the P-type region 619 is electrically coupled to the bias voltage ca2. Therefore, photogenerated holes can be collected and discharged by the P-type region 619.

7A shows a cross-sectional view of a light detection device with a surface depletion mode according to some embodiments. The light detection device 700a includes control metal wires 706a, 706b and read metal wires 708a, 708b. The control metal wires 706a, 706b and the read metal wires 708a, 708b are electrically coupled to a surface 702s of a germanium-based light absorbing material 702. The control metal wires 706a, 706b are electrically coupled to P-type regions 703a, 703b on the surface 702s, respectively, and the read metal wires 708a, 708b are electrically coupled to N-type regions 701a, 701b on the surface 702s, respectively. This embodiment forms an interlayer dielectric ILD on the surface 702s, and forms metals 721, 716a, 716b, 718a, 718b on the interlayer dielectric ILD. The metals 721, 716a, 716b, 718a, 718b can be biased to produce depletion regions 721d, 716ad, 716bd, 718ad, 718bd. The biases applied to the metals 721, 716a, 716b, 718a, 718b can be different or the same, or some of the metals 721, 716a, 716b, 718a, 718b can be floated.

Depletion region 712d can reduce the dark current between P-type region 703a and P-type region 703b. Depletion region 716ad can reduce the dark current between P-type region 703a and N-type region 701a. Depletion region 716bd can reduce the dark current between P-type region 703b and N-type region 701b. Depletion region 718a can reduce the dark current between N-type region 701a and another pixel (not shown in FIG. 7A). Depletion region 718b can reduce the dark current between N-type region 701b and another pixel (not shown in FIG. 7A). Therefore, by forming these surface depletion regions, power consumption and noise generation can be reduced.

As described above, metals 721, 716a, 716b, 718a, 718b can be biased to produce depletion regions 721d, 716ad, 716bd, 718ad, and 718bd. In other applications, metals 721, 716a, 716b, 718a, 718b can be biased to cause corresponding regions 721d, 716ad, 716bd, 718ad, 718bd to become accumulation or inversion instead of depletion.

In addition to reducing leakage current, metals 721, 716a, 716b, 718a, 718b can reflect the residual optical signal IL into the germanium-based light absorbing material 702, thereby being converted into electron-hole pairs accordingly. These metals 721, 716a, 716b, 718a, 718b act as reflectors to reflect light that is not completely absorbed and converted by the germanium-based light absorbing material 702 back to the germanium-based light absorbing material 702 for reabsorption. This will increase the overall absorption efficiency, thereby improving system performance.

In addition, FIG. 7B shows an alternative embodiment of the present disclosure. Compared with FIG. 7A, the embodiment adds polarized dielectric layers 721e, 716ae, 716be, 718ae, 718be (e.g., einsteinium dioxide), as shown in FIG. 7B. Because there are dipoles in the polarized dielectric layers 721e, 716ae, 716be, 718ae, 718be, depletion/accumulation/inversion regions 721d, 716ad, 716bd, 718ad, 718bd can be generated without biasing or biasing the metals 721, 716a, 716b, 718a, 718b with a small bias.

FIG7C shows a plan view of the light detection device 700b. Note that metals 721, 716a, 716b, 718a, 718b and polarized dielectric layers 721e, 716ae, 716be, 718ae, 718be can be optionally formed. The device implementer (fabricator) can design a light detection device including or excluding these elements based on different scenarios. In addition, in addition to adding metal and polarized dielectric in the vertical direction as shown in FIG7C, there is an alternative embodiment as shown in FIG7D, in which metals 723a, 723b and polarized dielectric layers 725a, 725b are added in the horizontal direction.

FIG8A shows a cross-sectional view of a light detection device with surface ion implantation according to some embodiments. The light detection device 800a includes control metal wires 806a, 806b and read metal wires 808a, 808b. The control metal wires 806a, 806b and the read metal wires 808a, 808b are electrically coupled to a surface 802s of a germanium-based light absorbing material 802. The control metal wires 806a, 806b are electrically coupled to P-type regions 803a, 803b on the surface 802s, respectively, and the read metal wires 808a, 808b are electrically coupled to N-type regions 801a, 801b on the surface 802s, respectively. In order to have a high surface resistance that suppresses surface leakage current, the embodiment uses neutral ion implantation as a surface treatment. As shown in the figure, ion treated regions 829, 831a, 831b, 833a, 833b are implanted with ions (e.g., silicon, germanium, carbon, hydrogen) where the accelerated ions collide with the species and cause damage to the atomic periodicity or crystal structure in the implanted region. Lattice damage such as atomic vacancies and interstitials destroys the periodic potential seen by the electron envelope function, so the electron/hole gains a higher probability of being scattered. This effect results in lower mobility and thus higher resistance.

FIG8B shows a plan view of a light detection device 800a with surface ion implantation according to some embodiments. As shown, ion treatment regions 829, 831a, 831b, 833a, 833b are vertically formed between doping regions 801a, 801b, 803a, 803b. In some embodiments, the ion treatment region can be formed elsewhere, so this embodiment is only for reference and not limitation.

9A shows a cross-sectional view of a light detection device with inter-pixel isolation. The light detection device 900a includes control metal lines 906a, 906b and readout metal lines 908a, 908b. The control metal lines 906a, 906b and the readout metal lines 908a, 908b are electrically coupled to a surface 902s of a germanium-based light absorbing material 902. The control metal lines 906a, 906b are electrically coupled to P-type regions 903a, 903b on the surface 902s, respectively, and the readout metal lines 908a, 908b are electrically coupled to N-type regions 901a, 901b on the surface 902s, respectively. This embodiment includes an isolation region 924 formed as a ring surrounding the germanium-based light absorbing material 902. In one implantation, the isolation region 924 is an N-type region. It depends on the type of the germanium-based light absorbing material 902, the semiconductor substrate 904 and other factors, and the isolation region 924 can be realized by a P-type region. With the isolation region 924, the light detection device 900a has the effect of reducing crosstalk signals and/or powering adjacent devices.

FIG9B shows a plan view of a light detection device 900a with inter-pixel isolation. As shown, the isolation region 924 forms a whole ring. In other embodiments, the isolation region 924 may be segmented or truncated.

FIG9C shows a cross-sectional view of a light detection device with inter-pixel isolation. The light detection device 900c forms an additional narrow and shallow isolation region 924a within the isolation region 924. The doping concentration of the isolation region 924 is different from the doping concentration of the isolation region 924a. This can be used to suppress crosstalk through the surface conduction path.

FIG9D shows a cross-sectional view of a light detection device with inter-pixel isolation. The light detection device 900d forms an additional trench isolation region 924b extending from the isolation region 924a to the bottom surface of the semiconductor substrate 904. The trench isolation region 924b may be an oxide trench in which the electrical path between the germanium-based light absorbing material 902 and the adjacent element is blocked.

FIG9E shows a cross-sectional view of a light detection device with inter-pixel isolation. The light detection device 900e forms a trench isolation region 924b extending from the top surface of the semiconductor substrate 904 to the bottom surface of the semiconductor substrate 904. The trench isolation region 924a may be an oxide trench that blocks an electrical path between the germanium-based light absorbing material 902 and an adjacent element.

FIG10A shows a cross-sectional view of a light detection device according to some embodiments. The embodiment of FIG10A includes and combines elements from the above-described embodiments. The light detection device 1000a includes control metal wires 1006a, 1006b and read metal wires 1008a, 1008b. The control metal wires 1006a, 1006b and read metal wires 1008a, 1008b are electrically coupled to a surface 1002s of a germanium-based light absorbing material 1002. The control metal wires 1006a, 1006b are electrically coupled to P-type regions 1003a, 1003b on the surface 1002s, respectively. The read metal wires 1008a, 1008b are electrically coupled to N-type regions 1001a, 1001b on the surface 1002s, respectively. Similarly, the light detection device 1000a is able to obtain distance information through the optical signal IL. Specifically, when the optical signal IL enters the absorption region AR, it will be converted into electron-hole pairs and then separated by the electric field generated between the P-type regions 1003a, 1003b. According to the control signals cs1, cs2, the electrons can move to the N-type region 1001a or the N-type region 1001b. In some embodiments, the control signals cs1 and cs2 are differential voltage signals. In some embodiments, one of the control signals cs1 and cs2 is a constant voltage signal (e.g., 0.5v), and the other control signal is a time-varying voltage signal (e.g., a sinusoidal signal, a timer signal, or a pulse signal; between 0V and 1V). Due to the distance between the light detection device 1000a and the target object (not shown in FIG. 10A ), the optical signal IL has a phase delay relative to the incident light emitted by the emitter (not shown in FIG. 10A ). The transmitted light is modulated by the modulation signal, and the electron-hole pairs are demodulated by another modulation signal through the control metal wires 1006a and 1006b. The electrons or holes stored in the capacitor 1010a and the capacitor 1010b will change according to the distance. Therefore, the light detection device 1000a can obtain distance information based on the voltage v1 on the capacitor 1010a and the voltage v2 on the capacitor 1010b. According to one embodiment, the distance information can be derived based on the calculation with the voltage v1 and the voltage v2 as input variables. For example, in a pulse time-of-flight configuration, a voltage ratio related to voltage v1 and voltage v2 is used as an input variable. In another example, in a continuous wave time-of-flight configuration, in-phase and quadrature voltages related to voltage v1 and voltage v2 are used as input variables.

In addition to the detection distance, the photodetection device 1000a also includes different depth designs for the N-type regions 1001a, 1001b and the P-type regions 1003a, 1003b, and also adds N-wells 1011a, 1011b, which can reduce the leakage current between the P-type region 1003a and the P-type region 1003b. Second, the photodetection device 1000a includes a well-shaped P-type region 1019 covering the germanium-based light absorbing material 1002, which can collect and discharge holes through a bias voltage ca2. Third, the photodetection device 1000a includes a passivation layer 1014 and an interlayer dielectric ILD to process the surface 1002s into defects existing on the surface 1002s. Fourth, the light detection device 1000a includes a metal 1021, which can be biased or unbiased to produce accumulation, inversion or depletion on the surface 1002s. In addition, the metal 1021 can be used as a reflector to reflect the residual optical signal IL back into the germanium-based light absorbing material 1002 to be converted into electron-hole pairs. Fifth, the light detection device 1000a adds silicides 1013a, 1013b, 1015a, 1015b to reduce voltage drops. Sixth, the light detection device 1000a can add an isolation region 1024, or it can be realized by doping materials or insulating oxides. The isolation region 1024 can be electrically coupled to the bias ca3. In some embodiments, the isolation region 1024 and the P-type region 1019 can be electrically coupled together through a metal layer, and the metal layer remains floating or electrically coupled to a voltage source.

FIG10B shows a cross-sectional view of a light detection device according to some embodiments. The structure of the light detection device 1000b is similar to that of the light detection device 1000a. The difference is that the control metal lines 1006a, 1006b in FIG10B are electrically coupled to the undoped regions 1005a, 1005b.

In addition, although the above-mentioned embodiment uses the germanium-based light absorbing material 1002 to absorb the optical signal IL, an embodiment without the germanium-based light absorbing material 1002 can be realized. As shown in FIG. 10C, the light detection device 1000c can use a semiconductor substrate 1004 as a light absorbing material. In some embodiments, the semiconductor substrate 1004 can be silicon, silicon germanium, germanium or vanadium compound. In addition, as shown in the embodiment of FIG. 10D, P-type regions 1003a, 1003b and N-wells 1011a, 1011b can be added on the surface 1002s of the semiconductor substrate 1004.

Light detection devices 1000a, 1000b, 1000c, and 1000d are shown to illustrate possible combinations of the above-mentioned embodiments (FIG. 1A to FIG. 9E). It should be understood that the device implementer can arbitrarily combine two or more of the above-mentioned embodiments to implement other light detection devices, and multiple combinations can be implemented.

Note that the doping concentration of the doped regions shown in the embodiments can be appropriately designed. Taking the embodiment of FIG. 10A as an example, the doping concentration of the N-type regions 1001a, 1001b and the doping concentration of the P-type regions 1003a, 1003b can be different. In one embodiment, the P-type regions 1003a, 1003b are lightly doped, while the N-type regions 1001a, 1001b are heavily doped. Typically, the doping concentration of light doping can be in the range of 10 ¹⁶ /cm ³ or lower to 10 ¹⁸ /cm ³ , while the doping concentration of high doping can be in the range of 10 ¹⁸ /cm ³ to 10 ²⁰ /cm ³ or higher. By adjusting the doping concentration, Schottky contacts can be formed between the control metal lines 1006a, 1006b and the P-type regions 1003a, 1003b, respectively; and ohmic contacts can be formed between the readout metal lines 1008a, 1008b and the N-type regions 1001a, 1001b, respectively. In this case, the resistance between the control metal lines 1006a, 1006b and the P-type regions 1003a, 1003b is higher than the resistance between the read metal lines 1008a, 1008b and the N-type regions 1001a, 1001b.

On the other hand, the doping types of these doping regions can also be implemented in different ways. Taking the embodiment of FIG. 10A as an example, if regions 1003a, 1003b are doped with N-type dopants, then P-type regions 1003a, 1003b can be replaced by N-type. Similarly, if regions 1001a, 1001b are doped with P-type dopants, then N-type regions 1001a, 1001b can be replaced by P-type. Therefore, an embodiment can be implemented in which doping regions 1001a, 1001b, 1003a and 1003b are all doped with the same type of dopant.

Please refer to FIG. 11A, which shows a plan view of a light detection device according to some embodiments. The light detection device 1100a includes control metal wires 1106a, 1106b, read metal wires 1108a, 1108b, N-type regions 1001a, 1001b, and P-type regions 1003a, 1003b on a germanium-based light absorbing material 1102. In this embodiment, the control metal wires 1106a, 1106b are located on the X-axis, however, the read metal wires 1108a, 1108b are not located on the X-axis. In this embodiment, the four terminals are not on the same axis, which can reduce the area of the light detection device 1100a. The geometric relationship between each element is shown in FIG. 11A.

FIG11B shows a plan view of a light detection device according to some embodiments. Compared with FIG11A , the control metal wires 1106a and 1106b are not located on the X-axis, but are aligned with the readout metal wires 1108a and 1108b in a direction perpendicular to the X-axis, respectively. Similarly, the geometric relationship between each element is shown in FIG11B .

FIG. 11C shows a plan view of a light detection device according to some embodiments. Control metal wires 1106a, 1106b are formed above the absorption region AR and are diagonally opposite to each other in the optical opening WD. Readout metal wires 1108a, 1108b are formed on the X-axis.

FIG. 11D shows a plan view of a light detection device according to some embodiments. The light detection device in FIG. 11D is similar to the light detection device in FIG. 11C , but the germanium-based light absorbing material 1102 is rotated so that the axis X in the germanium-based light absorbing material 1102 is in a diagonal direction. It can also reduce the total area of the light detection device.

FIG. 11E shows a plan view of a light detection device according to some embodiments. The difference between this embodiment and the previous embodiment is that the optical opening WD can be designed as an octagon. It can also be designed into other shapes (such as a circle, a hexagon, etc.).

Figures 11A-11D show some embodiments by adjusting the layout positions of the control metal lines 1106a, 1106b, the read metal lines 1108a, 1108b, the N-type regions 1001a, 1001b, and the P-type regions 1003a, 1003b. The implementer can also design different geometric relationships for these elements to reduce or minimize the chip area. These alternative embodiments are shown as references, not limitations.

The above-described light detection device uses a single photodetector as an embodiment, which is used for a single pixel application. The light detection device described below is an embodiment for a multi-pixel application (e.g., an image pixel array or an image sensor).

In some embodiments, the light detection device can be designed to receive the same or different optical signals, for example, having the same or different wavelengths, having the same or multiple modulations, or operating in different time frames.

Please refer to FIG. 12A. The light detection device 1200a includes a pixel array, which, as an example, includes four pixels 12021, 12022, 12023, and 12024. According to the embodiment described herein, each pixel is a photodetector. In one embodiment, an optical signal IL containing a wavelength λ1 is received by pixels 12021 and 12024 in the array, and an optical signal IL containing a wavelength λ2 is received by pixels 12022 and 12023 in the array. In another embodiment, there is only one wavelength λ, but there are multiple modulation frequencies f _mod1 and f _mod2 (or more). For example, the pixels 12021 and 12024 are applied with the modulation frequency f _mod1 to demodulate the frequency component in the optical signal IL, and the pixels 12022 and 12023 are applied with the modulation frequency f _mod2 to demodulate the frequency component in the optical signal IL. In another embodiment, similarly, there is only one light wavelength, but there are multiple modulation frequencies f _mod1 and f _mod2 (or more). However, at time t1, the pixels in the array are driven by the modulation frequency f _mod1 to demodulate the frequency component in the optical signal, and at another time t2, the pixels in the array are driven by the modulation frequency f _mod2 to demodulate the frequency component in the optical signal IL, so the pixel array 1200a operates in a time division multiplexing mode.

In an alternative embodiment, light wavelengths λ1 and λ2 are modulated by f _mod1 and f _mod2 , respectively, and then collected by pixel array 1200a. At time t1, pixel array 1200a operates at f _mod1 to demodulate the optical signal in λ1; and at time t2, pixel array 1200a operates at f _mod2 to demodulate the optical signal in λ2. In an alternative embodiment, optical signals IL having light wavelengths λ1 and λ2 are modulated by f _mod1 and f _mod2 , respectively, pixels 12021, 12024 are driven by f _mod1 , and pixels 12022, 12023 are driven by f _mod2 to simultaneously demodulate the input modulated optical signals IL. Those skilled in the art will readily recognize that other combinations of light wavelengths, modulation schemes, and time divisions can be implemented.

Please refer to FIG. 12B. The light detection device 1200b includes four pixels 12021, 12022, 12023, 12024. Each pixel is a photodetector and the embodiments disclosed above can be used. In addition to the layout shown in FIG. 12A, the pixels 12021, 12022, 12023, 12024 can be arranged in a staggered layout as shown in FIG. 12B, where the width and length of each pixel are placed in a direction perpendicular to the width and length of the adjacent pixels.

13A shows a block diagram of a light detection device 1300a using a modulation scheme with phase variation according to some embodiments. The light detection device 1300a is an indirect time-of-flight based depth image sensor capable of detecting distance information to a target object 1310. The light detection device 1300a includes a pixel array 1302, a laser diode driver 1304, a laser diode 1306, and a timer driver circuit 1308 including timer drivers 13081, 13082. According to embodiments disclosed herein, the pixel array 1302 includes a plurality of photodetectors. Typically, the sensor chip generates and sends a timing signal that is used to λ1) modulate the transmitted optical signal through the laser diode driver 1304, and λ2) demodulate the received/absorbed optical signal through the pixel array 1302. To obtain depth information, all photodetectors in the entire pixel array are demodulated by referencing the same timer, which is changed in time sequence to four possible orthogonal phases, such as 0°, 90°, 180°, and 270°, and there is no phase change on the transmitter side. However, in this embodiment, the 4 orthogonal phase changes are implemented on the transmitter side, and there is no phase change on the receiving side, as described below.

Please refer to FIG. 13B, which shows a timing diagram of timer signals CLK1 and CLK2 generated by timer drivers 13081 and 13082, respectively. The timer signal CLK1 is a modulation signal with four orthogonal phase changes, such as 0°, 90°, 180° and 270°, and the timer signal CLK2 is a demodulation signal without phase change. Specifically, the timer signal CLK1 drives the laser diode driver 1304 so that the laser diode 1306 can generate modulated transmission light TL. The timer signal CLK2 and its inverted signal CLK2' (not shown in FIG. 13B) are used as the control signal cs1 and the control signal cs2 (shown in the above embodiment) for demodulation, respectively. In other words, the control signal cs1 and the control signal cs2 in this embodiment are differential signals. This embodiment can avoid the possible time coherence inherent in the image sensor due to the storage effect caused by the parasitic resistor-capacitor.

Please refer to Figures 13C and 13D. In Figure 13C. Compared with Figure 13A, the photodetection device 1300c uses two demodulation schemes on the receiving side. The pixel array 1302 includes two parts, a first pixel array 1302a and a second pixel array 1302b. The first demodulation scheme applied to the first pixel array 1302a and the second demodulation scheme applied to the second pixel array 1302b are different in time sequence. For example, the first pixel array 1302a applies the first demodulation scheme, in which the phase changes in the time sequence are 0°, 90°, 180°, and 270°. The second pixel array 1302a applies the second demodulation scheme, in which the phase changes in the time sequence are 90°, 180°, 270°, and 0°. The net effect is that the phase change in the first pixel array 1302a is in phase with the phase change in the second pixel array 1302b, with no phase change on the transmit side. This operation may reduce the maximum transient current drawn from the power supply if the demodulated waveform is not a perfect square wave.

Please refer to Figure 13E, which shows a modulation scheme using a light detection device 1300c. Compared with Figure 13D, this embodiment applies a phase change to the transmission side, but does not apply a phase change to the two different pixel arrays 1302a, 1302b on the receiving side, except that two different constant phases are set to the two different pixel arrays 1302a, 1302b, and the two different constant phases are orthogonal to each other. For example, the modulation signal on the transmission side is a timer signal CLK1, where the phase changes in the time series are 0°, 90°, 180° and 270°. The demodulation signal on the receiving side is a timer signal CLK2, CLK3. The timer signal CLK2 is used to demodulate the incident optical signal IL absorbed by the pixel array 1302a, which has a constant phase of 0. The timer signal CLK3 is used to demodulate the incident optical signal IL absorbed by the pixel array 1302b, which has a constant phase of 90°.

Although the embodiments shown in FIGS. 13A-13E use a timer signal with a 50% duty cycle as the modulation and demodulation signals, in other possible implementations, the duty cycle may be different (e.g., 30% duty cycle). In some embodiments, a sine wave is used as the modulation and demodulation signals instead of a square wave.

FIG. 14 illustrates a process using a light detection device that uses a modulation scheme with phase variation according to some embodiments. In other embodiments, other entities perform some or all steps of the process. Likewise, embodiments may include different and/or additional steps, or perform the steps in a different order.

In the embodiment of FIG. 14 , the optical detection method includes step 1401: sending an optical signal modulated by a first modulation signal, wherein the optical signal is modulated by the first modulation signal with one or more predetermined phases for multiple time frames; step 1402: the photodetector receives the reflected optical signal; step 1403: demodulating the reflected optical signal by one or more demodulation signals, wherein the one or more demodulation signals are signals with one or more predetermined phases for multiple time frames; and step 1404: outputting at least one voltage signal on the capacitor. In the method, the photodetector can use the embodiments mentioned in the present disclosure or variations thereof.

In some embodiments, the pixel isolation region described with reference to FIGS. 9A-9E , i.e., pixel isolation region 924, is eliminated in the x-direction, e.g., in a direction parallel to the substrate surface. By removing the pixel isolation region, the pixel size can be reduced. FIG. 15A shows a cross-sectional view of a light detection device with adjacent pixel structures according to some embodiments.

As shown in FIG. 15A , the light detection device includes two adjacent pixel structures without isolation in the x direction parallel to the device surface. The optical signal Ψ1 is focused to the absorption region 108, such as the absorption region 208 in FIG. 15A , where the photocurrent generated will flow into all electrodes 205 , 206 , 216 , 215 . In other words, the photogenerated electrons generated from the absorption region 208 due to the optical signal Ψ1 will be collected by the N+ terminals 205 , 215 and the N+ terminals 225 , 235 . In some embodiments, the photogenerated electrons generated in the absorption region 208 due to the optical signal Ψ1 are mainly collected by the N+ terminals 205 , 215 , and secondarily by the N+ terminals 225 , 235 .

Similarly, the optical signal Ψ2 is incident on the absorption region 218, where the photocurrent generated will be collected by the N+ terminals 225, 235 and 205, 215. In some embodiments, the photogenerated electrons from the absorption region 218 are mainly collected by the N+ terminals 225, 235, and secondarily by the N+ terminals 205, 215.

In some embodiments, the N+ terminals 215, 225 are biased to provide a depletion region, thereby reducing the number of photogenerated electrons generated by the Ψ1 optical signal in the absorption region 1507 that are collected by the N+ terminals 225, 235.

FIG15B illustrates a plan view of a light detection device according to some embodiments. In the structure depicted in FIG15B, the two pixel examples depicted in FIG15A are along a horizontal line in the plane of the device.

In some embodiments, the system described above with reference to Figures 15A and 15B can be extended to multiple pixels because the system is mathematically linear. For example, the proposed algorithm can be extended to multiple pixels (>3 pixels) in a horizontal line.

FIG. 15C shows a cross-sectional view of a light detection device according to some embodiments. FIG. 15C depicts a structure of n pixels arranged in a row without isolation between pixels. Optical signals, such as optical signals of Ψ1, Ψ2, and Ψn, enter respective absorption regions through array openings to prevent light irradiated outside the absorption openings from being absorbed. Optionally, in some embodiments, a floating p region may be inserted in the light detection device between terminal C2 and terminal C3 to reduce crosstalk between pixels.

Figures 15D-15E show plan views of light detection devices according to some embodiments. Figure 15D shows an array layout, and is an alternative layout to the array layout shown in Figure 15B, which can reduce the area occupied by the array more than the layout shown in Figure 15B. As shown in Figure 15D, the endpoints, such as endpoint C1, endpoint M1, endpoint M2, and endpoint C2 in Figure 15C, are in the same horizontal line.

FIG. 15E is an alternative structural design to FIG. 15D . Only one row of the array is shown here. In this design, the collection terminals C1 and C2, such as the terminals C1 and C2 in FIG. 15C , can be moved in the lateral (y) direction (relative to the plane of the substrate), and the terminals M1 and M2 (such as the terminals M1 and M2 in FIG. 15C ) can be moved closer to or into the absorption region, such as closer to or into the optical opening 108. Compared with FIG. 15D , this design increases the effective distance between the terminals C2 and C3, thereby reducing the crosstalk between the terminals C2 and C3. In some embodiments, the staggered layout of the N+ terminals causes some N+ terminals to not be completely blocked by the corresponding depletion regions, so the generated photocurrent will be collected by more adjacent pixel terminals.

Additionally, as described above with reference to FIG. 15D , a floating p-doped region may be implanted to suppress n-to-n type crosstalk. Compared to FIG. 15D , the layout depicted in FIG. 15E includes additional space in the x-direction, e.g., parallel to the substrate, to place the floating p region.

Similarly, as described above with reference to Figures 15A and 15B, the apparatus of Figures 15C-15E can, for example, use device symmetry to assume a pixel array including more than 4 pixel elements. For example, a fully interleaved 2n×2n array can be envisioned without isolation between pixels. In addition, component symmetry can be used to assume manufacturing non-idealities of the calibration array. For example, device offsets or light incidence angle tilts between endpoints C1 and C2 can be averaged during the modulation scheme, for example, as described with reference to Figures 13A-13E, where the alternating phases of 0 degrees and 180 degrees are in phase (e.g., for a square wave). Similarly, two or n merged pixels in an n-pixel array can follow the same calibration.

2。光檢測設備還包括支撐吸收區域1610的基底1620。每個子像素1600a、1600b包括一檢測區域1613和位於檢測區域1613兩邊的兩個開關(未標記)。每個開關包括一第一導電接觸和一第二導電接觸。例如，如圖16A所示，子像素1600a或1600b的一第一開關(未標記)包括一第一導電接觸1631a和一第二導電接觸1632a。子像素1600a或1600b的第二開關(未標記)包括一第一導電接觸1631b和一第二導電接觸1632b。子像素的兩個開關的電荷收集可以隨時間改變，使得成像系統可以確定感測光的相位資訊。成像系統可以使用相位資訊來分析與立體物件相關聯的特徵，包括深度資訊或材料成分。成像系統還可以使用相位資訊來分析與面部識別、眼睛跟蹤、手勢識別、立體模型掃描/視頻記錄、運動跟 蹤和/或增強/虛擬實境應用相關聯的特徵。 FIG16A shows a cross-sectional view of a light detection device according to some embodiments. The light detection device includes a pixel 1600, the pixel 1600 includes an absorption region 1610, and two sub-pixels 1600a, 1600b coupled to the same absorption region 1610. In some embodiments, the number of sub-pixels is a positive integer and

2. The light detection device also includes a substrate 1620 that supports the absorption region 1610. Each sub-pixel 1600a, 1600b includes a detection region 1613 and two switches (not labeled) located on both sides of the detection region 1613. Each switch includes a first conductive contact and a second conductive contact. For example, as shown in Figure 16A, a first switch (not labeled) of the sub-pixel 1600a or 1600b includes a first conductive contact 1631a and a second conductive contact 1632a. The second switch (not labeled) of the sub-pixel 1600a or 1600b includes a first conductive contact 1631b and a second conductive contact 1632b. The charge collection of the two switches of the sub-pixel can change over time, so that the imaging system can determine the phase information of the sensed light. Imaging systems can use phase information to analyze features associated with three-dimensional objects, including depth information or material composition. Imaging systems can also use phase information to analyze features associated with facial recognition, eye tracking, gesture recognition, stereo model scanning/video recording, motion tracking, and/or augmented/virtual reality applications.

In some embodiments, the detection region 1613 is located between the two second conductive contacts 1632a, 1632b. The two second conductive contacts 1632a, 1632b are closer to the detection region 1613 than the first conductive contacts 1631a, 1631b. In some embodiments, the two detection regions 1613 of the two sub-pixels 1600a, 1600b are in the same absorption region 1610. The first conductive contacts 1631a, 1631b and the second conductive contacts 1632a, 1632b are formed on the same absorption region 1610.

In some embodiments, pixel 1600 includes multiple readout circuits and multiple control signals. For example, pixel 1600 may include four readout circuits and four control signals. For example, pixel 1600 includes two first readout circuits 1671a and two second readout circuits 1671b. Pixel 1600 includes two first control signals 1672a and two second control signals 1672b. A set of first control signals 1672a and second control signals 1672b are electrically coupled to two switches and used to control two switches in a single sub-pixel. A set of first readout circuits 1671a and second readout circuits 1671b are electrically coupled to two switches and used to process the collected charge. In other words, the first control signal 1672a and the second control signal 1672b control the electrons or holes generated by the photons absorbed in the detection region 1613 to be processed by the first readout circuit 1671a or the second readout circuit 1671b in the single sub-pixel 1600a or 1600b. In some embodiments, the first control signal 1672a can be fixed at a voltage value Vi, and the second control signal 1672b can alternate between the voltage values Vi±△V. In some embodiments, the first control signal 1672a and the second control signal 1672b can be different voltages from each other. In some embodiments, one of the control signals is a constant voltage signal (e.g., 0.5V) and the other control signal is a time-varying voltage signal (e.g., a sinusoidal signal, a clock signal, or a pulse signal operating between 0V and 1V). The direction of the bias value determines the drift direction of the charge generated from the absorption region 1610.

Two first readout circuits 1671a are electrically coupled to two first conductive contacts 1631a of sub-pixels 1600a and 1600b in a one-to-one relationship. Two second readout circuits 1671b are electrically coupled to two first conductive contacts 1631b of sub-pixels 1600a and 1600b in a one-to-one relationship. The first conductive contacts 1631a and 1631b may be readout contacts. Two first control signals 1672a are electrically coupled to two second conductive contacts 1632a of sub-pixels 1600a and 1600b in a one-to-one relationship. Two second control signals 1672b are electrically coupled to two second conductive contacts 1632b of sub-pixels 1600a and 1600b in a one-to-one relationship. The second conductive contacts 1632a, 1632b may be control contacts.

In some embodiments, the portion of the absorption region 1610 directly below the second conductive contacts 1632a, 1632b can be intrinsic or include a dopant having a peak concentration of less than about 1×10 ¹⁵ cm ^3. The term “intrinsic” means that the portion of the semiconductor material directly below the second conductive contacts 1632a, 1632b has no intentional addition of dopants. In some embodiments, the second conductive contacts 1632a, 1632b on the absorption region 1610 can result in the formation of a Schottky contact, an Ohmic contact, or a combination of the two with intermediate characteristics, depending on various factors, including the material of the absorption region 1610, the second conductive contacts 1632a, 1632b, and the level of impurities or defects in the absorption region 1610.

The first control signal 1672a and the second control signal 1672b are used to control the collection of electrons generated by absorbed photons from the detection region 1613. For example, when voltage is used, if the first control signal 1672a is biased relative to the second control signal 1672b, an electric field is generated between the two portions directly below the second conductive contacts 1632a, 1632b, and free charges drift toward one of the two portions directly below the second conductive contacts 1632a, 1632b depending on the direction of the electric field.

In some embodiments, each switch of the sub-pixels 1600a and 1600b includes two first doped regions 1611a and 1611b respectively under the first conductive contacts 1631a and 1631b, and is formed in the same absorption region 1610. In other words, the four first doped regions 1611a and 1611b of the two sub-pixels 1600a and 1600b are formed in the same absorption region 1610. In some embodiments, the minimum width w1 between the first conductive contacts of two adjacent sub-pixels is smaller than the width of the absorption region 1610. For example, the minimum width between the first conductive contact 1631a of sub-pixel 1600a and the first conductive contact 1631b of sub-pixel 1600b is less than the width of the absorption region 1610.

In some embodiments, the first doped regions 1611a, 1611b have a first conductivity type. In some embodiments, the first doped regions 1611a, 1611b include a dopant. The peak concentration of the dopant in the first doped regions 1611a, 1611b depends on the material of the first conductive contacts 1631a, 1631b and the material of the absorption region 1610, for example, between 5×10 ¹⁸ cm ^-3 and 5×10 ²⁰ cm ^-3 . The first doped regions 1611a, 1611b are used to collect carriers generated from the absorption region 1610, and these carriers are further processed by the first readout circuit 1671a and the second readout circuit 1671b based on the control of the first control signal 1672a and the second control signal 1672b, respectively.

In the present disclosure, in the same light detection device, the type of carriers collected by the first doped region 1611a and the type of carriers collected by the first doped region 1611b are the same. For example, when the light detection device is configured to collect electrons, when the first switch of a single sub-pixel is turned on and the second switch of the same sub-pixel is turned off, the first doped region 1611a collects electrons of photocarriers generated from the detection region 1613, and when the second switch is turned on and the first switch is turned off, the first doped region 1611b also collects electrons of photocarriers generated from the detection region 1613.

In some embodiments, the light detection device may include a light shielding layer 1660 having a plurality of openings 1661 for defining the position of the detection region 1613 of each sub-pixel 1600a, 1600b. In other words, the opening 1661 is used to allow the incident optical signal to enter the absorption region 1610 and define the position of the detection region 1613. In some embodiments, when the incident light enters the absorption region 1610 from the bottom surface of the substrate 1620, the light shielding layer is located on the bottom surface of the substrate 1620 away from the absorption region 1610. In some embodiments, from the top view of the opening 1661, the shape of the opening 1661 may be an ellipse, a circle, a rectangle, a square, a rhombus, an octagon, or any other suitable shape.

In some embodiments, the light detection device further includes a plurality of optical elements (not shown) corresponding one-to-one on the plurality of sub-pixels. The optical elements gather the incident optical signal to enter the detection area 1613.

In some embodiments, since multiple sub-pixels 1600a, 1600b are integrated with a single absorption region 1610, the size of the light detection device is reduced, and the dark current from the interface of the substrate 1620 and the absorption region 1610 is reduced. In addition, the spatial resolution of the light detection device is improved, and the size of a single light detection device unit 1600 is reduced.

FIG. 16B shows a top view of a light detection device according to some embodiments. FIG. 16A shows a cross-sectional view along line A-A' in FIG. 16B. In some embodiments, the first conductive contacts 1631a, 1631b and the second conductive contacts 1632a, 1632b of the two sub-pixels 1600a, 1600b are aligned along the longer side of the absorption region 1610.

FIG16C shows a top view of a light detection device according to some embodiments. In some embodiments, FIG16A shows a cross-sectional view along line A-A' in FIG16C. In some embodiments, the cross-sectional view shown in FIG16A can be a cross-sectional view along any possible cross-sectional line of the light detection device. In some embodiments, the two first conductive contacts 1631a, 1631b of one of the two sub-pixels 1600a are arranged diagonally relative to the detection region 1613. In some embodiments, the absorption region 1610 includes two first sides 1616a, 1616b and two second sides 1617a, 1617b. The length of each first side 1616a, 1616b is longer than the length of each second side 1617a, 1617b. The first conductive contact 1631b of subpixel 1600a is closer to the first side 1616a than the first conductive contact 1631a of subpixel 1600b. The first conductive contact 1631a of subpixel 1600b is closer to the first side 1616b than the first conductive contact 1631b of subpixel 1600a. In some embodiments, the first conductive contact 1631b of subpixel 1600a is located between the first side 1616a and the first conductive contact 1631a of subpixel 1600b. In some embodiments, the first conductive contact 1631a of subpixel 1600b is located between the first side 1616b and the first conductive contact 1631b of subpixel 1600a. In some embodiments, the second conductive contact 1631b of the sub-pixel 1600a is aligned with the first conductive contact 1631a of the sub-pixel 1600b along the horizontal direction D1. As a result, the size of the light detection device can be further reduced.

FIG. 16D shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 16D is similar to the light detection device in FIG. 16A , and the differences are described as follows.

In some embodiments, the pixel 1600 further includes a blocking layer 1640 surrounding the absorption region 1610, that is, the detection region 1613 of the sub-pixels 1600a and 1600b is surrounded by the same blocking layer 1640. In some embodiments, the conductivity type of the blocking layer 1640 is different from the first conductivity type of each first doped region 1611a and 1611b. The blocking layer 1640 can block the photogenerated carriers in the absorption region 1610 from reaching the substrate 1620, increasing the collection efficiency of the photogenerated carriers of the sub-pixels 1600a and 1600b. The blocking layer 1640 can also block the photogenerated carriers in the substrate 1620 from reaching the absorption region 1610, which increases the speed of the photogenerated carriers of the sub-pixels. The blocking layer 1640 may include a material that is the same as the material of the absorption region 1610, the same as the material of the substrate 1620, or a material that is different from the material of the absorption region 1610 and the material of the substrate 1620. In some embodiments, the shape of the blocking layer 1640 may be, but is not limited to, a ring shape.

In some embodiments, the blocking layer 1640 includes a dopant having a peak concentration ranging from 10 ¹⁵ cm ⁻³ to 10 ²⁰ cm ⁻³ . The blocking layer 1640 can reduce crosstalk between two adjacent pixels 1600.

In some embodiments, the light detection device may further include a third conductive contact (not shown) electrically connected to the blocking layer 1640. The blocking layer 1640 may be biased through the third conductive contact to release carriers that are not collected by the first doped regions 1611a, 1611b of the sub-pixels 1600a, 1600b.

FIG16E shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG16E is similar to the light detection device in FIG16A, and the differences are described as follows.

In some embodiments, the light detection device further includes an isolation region 1650, which is disposed at two opposite sides of the absorption region 1610 from the cross-sectional view of the light detection device. The isolation region 1650 is outside the absorption region 1610 and physically separated from the absorption region 1610. In some embodiments, the detection regions 1613 of the sub-pixels 1600a and 1600b are surrounded by the same isolation region 1650. In some embodiments, the minimum width w1 between the first conductive contacts of two adjacent sub-pixels is smaller than the width of the isolation region 1650. For example, the minimum width between the first conductive contact 1631a of the sub-pixel 1600a and the first conductive contact 1631b of the sub-pixel 1600b is smaller than the width w2 of the isolation region 1650. In some embodiments, the isolation region 1650 is a trench filled with a dielectric material or an insulating material to serve as a resistance region between two adjacent pixels, preventing current from flowing through the isolation region 1650 and improving the insulation between adjacent pixels 1600. The dielectric material or the insulating material may include, but is not limited to, an oxide material including silicon dioxide (SiO ₂ ), or a nitride material including silicon nitride (Si ₃ N ₄ ). In some embodiments, the trench is filled with silicon.

In some embodiments, the isolation region 1650 extends from the upper surface 1621 of the substrate 1620 and extends from the upper surface 1621 to a predetermined depth. In some embodiments, the isolation region 1650 extends from the bottom surface 1622 of the substrate 1620 and extends from the bottom surface 1622 to a predetermined depth. In some embodiments, the isolation region 1650 penetrates the substrate 1620 from the upper surface 1621 and the lower surface 1622.

In some embodiments, the isolation region 1650 is a doped region having a conductivity type. The conductivity type of the isolation region 1650 may be different from or the same as the first conductivity type of the first doped regions 1611a, 1611b. The peak concentration of the isolation region 1650 may be in the range of 10 ¹⁵ cm ^-3 to 10 ²⁰ cm ^-3 .

The doping of the isolation region 1650 may generate a bandgap offset-induced potential energy barrier that prevents current from flowing through the isolation region 1650 and improves electrical isolation between adjacent pixels 1600. In some embodiments, the isolation region 1650 includes a semiconductor material different from the material of the substrate 1620. The interface between the two different semiconductor materials formed between the substrate 1620 and the isolation region 1650 may generate a bandgap offset-induced potential energy barrier that prevents current from flowing through the isolation region 1650 and improves electrical isolation between adjacent pixels 1600. In some embodiments, the shape of the isolation region 1650 may be a ring. In some embodiments, the isolation region 1650 may include two separate regions disposed on two opposite sides of the absorption region 1610.

FIG16F shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG16F is similar to the light detection device in FIG16E, and the differences are described as follows.

In some embodiments, the light detection device includes a blocking layer 1640 in FIG. 16D and an isolation region 1650 in FIG. 16E. The conductivity type of the isolation region 1650 is different from the conductivity type of the blocking layer 1640. For example, when the conductivity type of the blocking layer 1640 is P-type, the conductivity type of the isolation region 1650 is N-type.

In some embodiments, each switch of the sub-pixels 1600a and 1600b includes two second doped regions 1612a and 1612b, respectively, which are located under the second conductive contacts 1632a and 1632b, respectively, and are formed in the same absorption region 1610. In other words, the four second doped regions 1612a and 1612b of the two sub-pixels 1600a and 1600b are formed in the same absorption region 1610.

In some embodiments, the second doped regions 1612a, 1612b have a second conductivity type different from the first conductivity type. In some embodiments, each second doped region 1612a, 1612b is doped with a dopant. The peak concentration of the dopant in the second doped regions 1612a, 1612b depends on the material of the second conductive contacts 1632a, 1632b and the material of the absorption region 1610, for example, between 1×10 ¹⁷ cm ^-3 and 5×10 ²⁰ cm ^-3 . The second doped regions 1612a, 1612b form a Schottky or Ohmic contact with the second conductive contacts 1632a, 1632b. The second doped regions 1612a and 1612b are used to modulate carriers generated from the absorption region 1610 based on the control of the first control signal 1672a and the second control signal 1672b.

FIG16G shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG16G is similar to the light detection device in FIG16E, and the differences are described as follows.

In some embodiments, the light detection device includes a blocking layer 1640 in FIG. 16D and an isolation region 1650 in FIG. 16E .

In some embodiments, each sub-pixel may further include a first dielectric layer 1633a between the absorption region 1610 and the second conductive contact 1632a of the two sub-pixels 1600a, 1600b. Each sub-pixel may further include a second dielectric layer 1633b between the absorption region 1610 and the second conductive contact 1632b of the two sub-pixels 1600a, 1600b.

The first dielectric layer 1633a prevents current from being directly conducted from the second conductive contact 1632a to the absorption region 1610, but allows an electric field to be established in the absorption region 1610 in response to a voltage applied to the second conductive contact 1632a. The second dielectric layer 1633b prevents current from being directly conducted from the second conductive contact 1632b to the absorption region 1610, but allows an electric field to be established in the absorption region 1610 in response to a voltage applied to the second conductive contact 1632b. The established electric field can attract or repel electric carriers in the absorption region 1610.

FIG. 16H shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 16H is similar to the light detection device in FIG. 16F, and the differences are described as follows.

The first conductivity type of each first doped region 1611a, 1611b is the same as the second conductivity type of each second doped region 1612a, 1612b.

In some embodiments, the second conductive contact 1632a is located between the first doped region 1611a and the second doped region 1612a of a switch in a single sub-pixel. In some embodiments, the second conductive contact 1632b is located between the first doped region 1611b and the second doped region 1612b of another switch in a single sub-pixel.

In some embodiments, when the second conductive contact 1632a is in Schottky contact with the absorption region 1610, the first doped region 1611a, the second doped region 1612a, and the second conductive contact 1632a are considered as a first metal semiconductor field effect transistor (MESFET). In some embodiments, when the second conductive contact 1632b is in Schottky contact with the absorption region 1610, the first doped region 1611b, the second doped region 1612b, and the second conductive contact 1632b are considered as a second metal semiconductor field effect transistor.

FIG. 16I shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 16I is similar to the light detection device in FIG. 16G , and the differences are described as follows.

The first conductivity type of each first doped region 1611a, 1611b is the same as the second conductivity type of each second doped region 1612a, 1612b.

In some embodiments, the first dielectric layer 1633a is located between the absorption region 1610 and the second conductive contact 1632a. The second dielectric layer 1633b is located between the absorption region 1610 and the second conductive contact 1632b.

The first dielectric layer 1633a and the second dielectric layer 1633b prevent current from being conducted directly from the second conductive contact 1632a to the absorption region 1610 and directly from the second conductive contact 1632b to the absorption region 1610, respectively, but allow an electric field to be established in the absorption region 1610 in response to a voltage applied to the second conductive contact 1632a and the second conductive contact 1632b. The established electric field attracts or repels charge carriers in the absorption region 1610. In some embodiments, the second conductive contact 1632a, the first dielectric layer 1633a, the first doped region 1611a, and the second doped region 1612a are considered to be a first metal oxide semiconductor field-effect transistor (MOSFET). In some embodiments, the second conductive contact 1632b, the second dielectric layer 1633b, the first doped region 1611b, and the second doped region 1612b are considered as a second metal oxide semiconductor field effect transistor. In some embodiments, the first metal oxide semiconductor field effect transistor and the second metal oxide semiconductor field effect transistor may be enhancement mode. In some embodiments, the first metal oxide semiconductor field effect transistor and the second metal oxide semiconductor field effect transistor may be depletion type.

FIG16J shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG16J is similar to the light detection device in FIG16F, and the differences are described as follows.

In some embodiments, each of the sub-pixels 1600a, 1600b further includes two reverse doped regions 1613a, 1613b. Each reverse doped region 1613a, 1613b has a conductivity type different from the first conductivity type of the first doped region 1611a, 1611b. For example, if the light detection device is configured to process the collected electrons for further applications, the first doped regions 1611a, 1611b are N-type, the second doped regions 1612a, 1612b are P-type, and the reverse doped regions 1613a, 1613b are P-type. In some embodiments, the reverse doped regions 1613a and 1613b respectively surround or overlap a portion of the first doped regions 1611a and 1611b that is far from the second doped regions 1612a and 1612b, and another portion of the first doped regions 1611a and 1611b is not surrounded or overlapped by the reverse doped regions 1613a and 1613b. In some embodiments, the first doped regions 1611a and 1611b completely overlap or are completely surrounded by the reverse doped regions 1613a and 1613b, respectively. In some embodiments, the reverse doped regions 1613a and 1613b serve as dark current reduction regions to reduce the dark current of the sub-pixels 1600a and 1600b. Compared with the light detection device that does not include the reverse doped regions 1613a and 1613b overlapping the first doped regions 1611a and 1611b, the light detection device of this embodiment including the reverse doped regions 1613a and 1613b overlapping the first doped regions 1611a and 1611b has a thinner depletion layer, thereby reducing the dark current of the light detection device.

In some embodiments, the reverse doped regions 1613a, 1613b can reduce crosstalk between the two sub-pixels 1600a, 1600b. For example, the reverse doping region 1613b of sub-pixel 1600a that is closer to sub-pixel 1600b than the reverse doping region 1613a of sub-pixel 1600a and the reverse doping region 1613a of sub-pixel 1600b that is closer to sub-pixel 1600a than the reverse doping region 1613b of sub-pixel 1600b can enhance the resistance between the first doping region 1611b of sub-pixel 1600a and the first doping region 1611a of sub-pixel 1600b, thereby reducing the crosstalk between the two sub-pixels 1600a and 1600b.

In some embodiments, each reverse doped region 1613a, 1613b is doped with a dopant having a peak concentration. The peak concentration is not less than 1×10 ¹⁶ cm ^-3 . In some embodiments, the peak concentration of the dopant of the reverse doped regions 1613a, 1613b is lower than the peak concentration of the dopant of the first doped region 331. In some embodiments, the peak concentration of the dopant of the reverse doped regions 1613a, 1613b is between 1×10 ¹⁶ cm ^-3 and 1×10 ¹⁸ cm ^-3 .

FIG. 16K shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 16K is similar to the light detection device in FIG. 16F, and the differences are described as follows.

In some embodiments, the pixel further includes a third doped region 1614 in the absorption region 1610 and between two adjacent sub-pixels 1600a, 1600b, and the third doped region 1614 is physically separated from the first doped region 1611b of the sub-pixel 1600a and the first doped region 1611a of the sub-pixel 1600b. The third doped region 1614 has a conductivity type different from the first conductivity type of each first doped region 1611a, 1611b. In some embodiments, the third doped region 1614 includes a dopant having a peak concentration. The peak concentration is not less than 1×10 ¹⁶ cm ^-3 . In some embodiments, the peak concentration of the dopant in the third doped region 1614 is lower than the peak concentration of the dopant in the first doped regions 1611a and 1611b. In some embodiments, the peak concentration of the dopant in the third doped region 1614 is between 1 x 10 ¹⁸ cm ^-3 and 5 x 10 ²⁰ cm ^-3 .

In some embodiments, the third doped region 1614 can reduce the crosstalk between the two sub-pixels 1600a, 1600b.

In some embodiments, the light detection device may include a third doped region 1614 and reverse doped regions 1613a, 1613b, as shown in FIG. 16J.

FIG. 16L shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 16L is similar to the light detection device in FIG. 16J , and the differences are described as follows.

In some embodiments, pixel 1600 includes two common readout circuits and two common control signals. For example, pixel 1600 includes a first common readout circuit 1673a, a second common readout circuit 1673b, a first common control signal 1674a, and a second common control signal 1674b. The first common readout circuit 1673a is electrically coupled to both the first conductive contact 1631a of sub-pixel 1600a and the first conductive contact 1631b of sub-pixel 1600b. Therefore, the charge collected by the first doped region 1611a of sub-pixel 1600a and the first doped region 1611b of sub-pixel 1600b can be processed by the same first common readout circuit 1673a. The second common readout circuit 1673b is electrically coupled to both the first conductive contact 1631b of subpixel 1600a and the first conductive contact 1631a of subpixel 1600b. Therefore, the charge collected by the first doped region 1611b of subpixel 1600a and the first doped region 1611a of subpixel 1600b can be processed by the same second common readout circuit 1673b.

The first common control signal 1674a is electrically coupled to both the second conductive contact 1632a of subpixel 1600a and the second conductive contact 1632b of subpixel 1600b. Therefore, the first switch of subpixel 1600a and the second switch of subpixel 1600b can be simultaneously controlled by the same first common control signal 1674a. The second common control signal 1674b is electrically coupled to both the second conductive contact 1632b of subpixel 1600a and the second conductive contact 1632a of subpixel 1600b. Therefore, the second switch of subpixel 1600a and the first switch of subpixel 1600b can be simultaneously controlled by the same second common control signal 1674b.

The first common control signal 1674a can be fixed at a voltage value Vi, and the second common control signal 1674b can alternate between voltage values Vi±△V. In some embodiments, the first common control signal 1674a and the second common control signal 1674b can be different voltages from each other. In some embodiments, one of the control signals is a constant voltage signal (e.g., 0.5v), and the other control signal is a time-varying voltage signal (e.g., a sinusoidal signal, a timer signal, or a pulse signal operating between 0V and 1V).

FIG. 16M shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 16M is similar to the light detection device in FIG. 16J , and the differences are described as follows.

In some embodiments, pixel 1600 includes a common control signal 1674 electrically coupled to both second conductive contact 1632b of subpixel 1600a and second conductive contact 1632a of subpixel 1600b. As a result, the second switch of subpixel 1600a and the first switch of subpixel 1600b can be simultaneously controlled by the same second common control signal 1674a. The first switch of subpixel 1600a is independently controlled by first control signal 1672a. The second switch of subpixel 1600b is independently controlled by first control signal 1672b.

FIG. 16N shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 16N is similar to the light detection device in FIG. 16K, and the differences are described as follows.

In some embodiments, first conductive contacts 1631a, 1631b and second conductive contacts 1632a, 1632b are formed on the upper surface of substrate 1620. First doped regions 1611a, 1611b and second doped regions 1612a, 1612b are formed in substrate 1620. Each sub-pixel 1600a, 1600b includes absorption regions 1610 separated from each other. Detection regions 1613 defined by openings 1661 correspond to the absorption regions 1610, respectively. In some embodiments, a minimum width w1 between first conductive contacts of two adjacent sub-pixels is smaller than a width of isolation region 1650. For example, the minimum width w1 between the first conductive contact 1631a of sub-pixel 1600a and the first conductive contact 1631b of sub-pixel 1600b is smaller than the width w2 of the isolation region 1650.

The light detection device in FIG. 16N does not have the blocking layer 1640 described in FIG. 16K

Since the two switches of each sub-pixel are formed outside the absorption region 1610, the light detection device has a lower dark current.

FIG. 16O shows a cross-sectional view of a light detection device according to some embodiments. Pixels 1600, 1600' can be any embodiment of the present disclosure.

FIG16P shows a top view of a light detection device according to some embodiments. The light detection device includes a pixel 1600, and the pixel 1600 includes four sub-pixels 1600a, 1600b, 1600c, and 1600d. FIG16Q shows a cross-sectional view of one of the sub-pixels in the light detection device shown in FIG16P. Each of the sub-pixels 1600a, 1600b, 1600c, and 1600d includes an absorption region 1610 separated from another absorption region 1610. The second conductive contact 1632a of the sub-pixels 1600a, 1600b, 1600c, and 1600d is electrically coupled to a first common control signal, as shown in FIG16L. That is, the first switches of sub-pixels 1600a, 1600b, 1600c, and 1600d are simultaneously controlled by the first common control signal, as shown in FIG16L. The second conductive contacts 1632b of sub-pixels 1600a, 1600b, 1600c, and 1600d are electrically coupled to the second common control signal, as shown in FIG16L. That is, the second switches of sub-pixels 1600a, 1600b, 1600c, and 1600d are simultaneously controlled by the second common control signal, as shown in FIG16L.

The first conductive contacts 1631a of the sub-pixels 1600a, 1600b, 1600c, and 1600d are electrically coupled to a first common readout circuit, as shown in FIG. 16L. That is, the charges collected by the first doped regions 1611a of all the sub-pixels 1600a, 1600b, 1600c, and 1600d can be processed by the same first common readout circuit 1673a. The first conductive contacts 1631b of the sub-pixels 1600a, 1600b, 1600c, and 1600d are electrically coupled to a second common readout circuit, as shown in FIG. 16L. That is, the charges collected by the first doped regions 1611b of all the sub-pixels 1600a, 1600b, 1600c, and 1600d can be processed by the same second common readout circuit 1673b.

In some embodiments, one of the sub-pixels may further include a fourth doped region 1615 between the two second doped regions 1612a, 1612b. The fourth doped region 1615 has a conductivity type different from the conductivity type of the blocking layer 1640. The fourth doped region 1615 and the blocking layer 1640 may be a PN junction, so a vertical electric field is established between the fourth doped region 1615 and the blocking layer 1640. Holes and electrons of photocarriers generated from the absorption region 1610 can be separated by the vertical electric field between the fourth doped region 1615 and the blocking layer 1640, and the carriers to be collected can be gathered toward the fourth doped region 1615 and then move toward the first doped region 1611a or the first doped region 1611b based on the control of the first common control signal or the second common control signal. As a result, the light detection device has an improved demodulation contrast.

FIG. 17A shows a cross-sectional view of a light detection device according to some embodiments. The light detection device includes a pixel 1700, and the pixel 1700 includes an absorption region 1710. The light detection device also includes a substrate 1720 supporting the absorption region 1710. The pixel 1700 includes a detection region 1713 and two switches 1790 sandwiching the detection region 1713. Each switch 1790 includes a control region 1791 and a readout region 1792. In this embodiment, each readout region 1792 includes a first conductive contact 1731a, 1731b on a first surface of the absorption region 1710, and each control region 1791 includes a second conductive contact 1732a, 1732b on a first surface of the absorption region 1710.

In some embodiments, the pixel 1700 includes two readout circuits and two control signals. For example, the pixel 1700 includes a first readout circuit 1771a and a second readout circuit 1771b. The pixel 1700 includes a first control signal 1772a and a second control signal 1772b. The first control signal 1772a and the second control signal 1772b are electrically coupled to two control regions 1791 of two switches 1790 and are used to control the two switches in the pixel. The first readout circuit 1771a and the second readout circuit 1771b are electrically coupled to the readout region 1792 of the two switches and are used to process the collected charge. In other words, the first control signal 1772a and the second control signal 1772b control the electrons or holes generated by the photons absorbed in the detection area 1713 to be processed by the first readout circuit 1771a or the second readout circuit 1771b in the pixel 1700. In some embodiments, the first control signal 1772a can be fixed at a voltage value Vi, and the second control signal 1772b can alternate between the voltage value Vi±△V. In some embodiments, the first control signal 1772a and the second control signal 1772b can be different voltages from each other. In some embodiments, one of the control signals is a constant voltage signal (e.g., 0.5v), and the other control signal is a time-varying voltage signal (e.g., a sinusoidal signal, a timer signal, or a pulse signal operating between 0V and 1V). The direction of the bias value determines the drift direction of the charge generated from the absorption region 1710.

In some embodiments, the detection region 1713 is located between the second conductive contacts 1732a and 1732b. The two second conductive contacts 1732a and 1732b are closer to the detection region 1713 than the first conductive contacts 1731a and 1731b. The first conductive contacts 1731a and 1731b and the second conductive contacts 1732a and 1732b are formed on the same absorption region 1710.

The first readout circuit 1771a is electrically coupled to the first conductive contact 1731a of the pixel 1700 in a one-to-one relationship. The second readout circuit 1771b is electrically coupled to the first conductive contact 1731b of the pixel 1700 in a one-to-one relationship. The first conductive contacts 1731a, 1731b can be used as readout contacts. The first control signal 1772a is electrically coupled to the second conductive contact 1732a of the pixel 1700 in a one-to-one relationship. The second control signal 1772b is electrically coupled to the second conductive contact 1732b of the pixel 1700 in a one-to-one relationship. The second conductive contacts 1732a, 1732b can be used as control contacts.

In some embodiments, the portion of the absorption region 1710 directly below the second conductive contacts 1732a, 1732b can be intrinsic or include a dopant having a peak concentration less than about 1×10 ¹⁵ cm ^3. The term "intrinsic" refers to the portion of the semiconductor material directly below the second conductive contacts 1732a, 1732b having no dopant added. In some embodiments, the second conductive contacts 1732a, 1732b on the absorption region 1710 can result in the formation of a Schottky contact, an Ohmic contact, or a combination of the two with intermediate characteristics, depending on various factors, including the material of the absorption region 1710, the second conductive contacts 1732a, 1732b, and impurities or defects in the absorption region 1710.

The first control signal 1772a and the second control signal 1772b are used to control the collection of electrons generated by absorbed photons from the detection region 1713. For example, when voltage is used, if the first control signal 1772a is biased relative to the second control signal 1772b, an electric field is generated between the two portions directly below the second conductive contacts 1732a, 1732b, and free charges drift toward one of the two portions directly below the second conductive contacts 1732a, 1732b depending on the direction of the electric field.

In some embodiments, the light detection device may include a light shielding layer (not shown) having a plurality of openings (not shown), the openings being used to define the position of the detection region 1713 of each pixel 1700. In other words, the opening is used to allow the incident optical signal to enter the absorption region 1710 and define the detection region 1713. In some embodiments, when the incident light enters the absorption region 1710 from the bottom surface of the substrate 1720, the light shielding layer is located on the bottom surface of the substrate 1720 away from the absorption region 1710. In some embodiments, the shape of the opening may be an ellipse, a circle, a rectangle, a square, a rhombus, an octagon, or any other suitable shape, as viewed from the top view of the opening.

In some embodiments, the light detection device further includes a plurality of optical elements (not shown) located one-to-one on the pixels. The optical elements gather the incident optical signal to enter the detection area 1713.

In this embodiment, conductive contact 1731a and conductive contact 1732a are similar to the first conductive contact 1631a and the second conductive contact 1632a mentioned in FIG. 16A. Other features of these components will not be described in detail.

FIG17B shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG17B is similar to the light detection device in FIG17A, and the differences are described as follows.

In some embodiments, pixel 1700 further includes a first well region 1765 and a second well region 1766 in substrate 1720, and first well region 1765 and second well region 1766 are disposed next to absorption region 1710. The conductivity type of first well region 1765 is different from the conductivity type of second well region 1766. Conductive contact 1767 is formed and disposed on first well region 1765 and electrically connected to first well region 1765, and conductive contact 1768 is formed and disposed on second well region 1766 and electrically connected to second well region 1766. In addition, conductive contact 1767 and conductive contact 1768 are electrically connected to each other (which means that first well region 1765 and second well region 1766 are also electrically connected to each other). In some embodiments, the doping concentration of the first well region 1765 may be in the range of 10 ¹⁶ cm ^-3 to 10 ²⁰ cm ^-3 . The doping concentration of the second well region 1766 may be in the range of 10 ¹⁶ cm ^-3 to 10 ²⁰ cm ^-3 .

In some embodiments, the absorption region 1710 may not completely absorb incident photons in the optical signal. For example, if the absorption region 1710 does not completely absorb incident photons in a near-infrared optical signal (not shown), the near-infrared optical signal may penetrate into the substrate 1720, which may absorb the penetrating photons and generate photocarriers deep in the substrate 1720, which slowly recombine. These slow photocarriers have a negative impact on the operating speed of the light detection device.

To further remove slow photocarriers, pixel 1700 may include a connection that shorts first well region 1765 to second well region 1766. For example, the connection may be formed by a silicide process or deposited metal pads, such as conductive contact 1767 and conductive contact 1768, which connect first well region 1765 to second well region 1766. The short circuit between first well region 1765 and second well region 1766 allows photocarriers generated in substrate 1720 to recombine at the short circuit node, thereby increasing the operating speed of the pixel.

In this embodiment, the structure in which the first well region 1765 and the second well region 1766 are connected together can be simply referred to as a "short circuit structure" 1760. In subsequent embodiments, if a "short circuit structure" is mentioned, it means that such a structure exists (at least including a first well region and a second well region with different conductivity types electrically connected to each other).

In addition, in this embodiment, only one short-circuit structure 1760 is disclosed, but in other embodiments, the pixel may include two or more short-circuit structures respectively arranged on both sides of the absorption region 1710. The two short-circuit structures 1760 may be arranged symmetrically along the long axis of the absorption region 1710, or the two short-circuit structures 1760 may be arranged symmetrically along the short axis of the absorption region 1710, which should also be within the scope of the present disclosure.

FIG. 17C shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 17C is similar to the light detection device in FIG. 17B , and the differences are described as follows.

In some embodiments, the light detection device further includes an isolation region 1725, which is disposed at two opposite sides of the absorption region 1710, as viewed from a cross-sectional view of the light detection device. The isolation region 1725 is outside the absorption region 1710 and physically separated from the absorption region 1710. In some embodiments, a short circuit structure 1760 is located between the isolation region 1725 and the absorption region 1710. In some embodiments, the isolation region 1725 is a trench filled with a dielectric material or an insulating material to serve as a high resistance region between two adjacent pixels, preventing current from flowing through the isolation region 1725 and improving electrical insulation between the pixel 1700 and other adjacent pixels (not shown). The dielectric material or insulating material may include, but is not limited to, an oxide material including silicon dioxide, or a nitride material including silicon nitride (Si ₃ N ₄ ). In some embodiments, the trench is filled with silicon.

In some embodiments, the isolation region 1725 extends from the upper surface of the substrate 1720 and extends from the upper surface to a predetermined depth. In some embodiments, the isolation region 1725 extends from the bottom surface of the substrate 1720 and extends from the bottom surface to a predetermined depth. In some embodiments, the isolation region 1725 penetrates the substrate 1720 from the upper surface and the lower surface.

In some embodiments, the isolation region 1725 is a doped region having a conductive type. The peak concentration of the isolation region 1650 may be in the range of 10 ¹⁵ cm ^-3 to 10 ²⁰ cm ^-3 . In some embodiments, a narrow and shallow isolation region 1735 is formed inside the isolation region 1725. The peak concentration of the shallow isolation region 1735 is different from the peak concentration of the isolation region 1725. This can be used to suppress crosstalk through the surface conduction path.

The doping of the isolation region 1725 can generate a bandgap offset-induced potential energy barrier that prevents current from flowing through the isolation region 1725 and improves electrical isolation between the pixel 1700 and other adjacent pixels (not shown). In some embodiments, the isolation region 1725 includes a semiconductor material different from the material of the substrate 1720. The interface between the two different semiconductor materials formed between the substrate 1720 and the isolation region 1725 can generate a bandgap offset-induced potential energy barrier that prevents current from flowing through the isolation region 1725 and improves electrical isolation between the pixel 1700 and other adjacent pixels (not shown). In some embodiments, the shape of the isolation region 1725 can be a ring. In some embodiments, the isolation region 1725 may include two separate regions disposed on two opposite sides of the absorption region 1710. In some embodiments, both separate regions may extend from the upper surface of the substrate 1720 and extend from the upper surface to a predetermined depth. In some embodiments, both discrete regions may extend from the bottom surface of the substrate 1720 and extend from the bottom surface to a predetermined depth.

FIG. 17D shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 17D is similar to the light detection device in FIG. 17C, and the differences are described as follows.

In some embodiments, each switch 1790 of the pixel 1700 includes two first doped regions 1711a, 1711b, respectively located below the first conductive contacts 1731a, 1731b and formed in the absorption region 1710. In other words, the two first doped regions 1711a, 1711b of the pixel 1700 are formed in the absorption region 1710.

In some embodiments, the first doped regions 1711a, 1711b are of the first conductivity type. In some embodiments, each of the first doped regions 1711a, 1711b is doped with a dopant. The peak concentration of the dopant in each of the first doped regions 1711a, 1711b depends on the material of the first conductive contacts 1731a, 1731b and the material of the absorption region 1710, for example, between 5×10 ¹⁸ cm ^-3 and 5×10 ²⁰ cm ^-3 . The first doped regions 1711a and 1711b are used to collect carriers generated from the absorption region 1710, and these carriers are further processed by the first readout circuit 1771a and the second readout circuit 1771b based on the control of the first control signal 1772a and the second control signal 1772b, respectively.

In the present disclosure, in the same light detection device, the type of carriers collected by the first doped region 1711a and the type of carriers collected by the first doped region 1711b are the same. For example, when the light detection device is configured to collect electrons, when the first switch of a pixel is turned on and the second switch of the same pixel is turned off, the first doped region 1711a collects electrons of photocarriers generated from the detection region 1713, and when the second switch is turned on and the first switch is turned off, the first doped region 1711b also collects electrons of photocarriers generated from the detection region 1713.

FIG. 17E shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 17E is similar to the light detection device in FIG. 17D , and the differences are described as follows.

In some embodiments, each switch 1790 of the pixel 1700 includes two second doped regions 1712a, 1712b, respectively located under the second conductive contacts 1732a, 1732b and formed in the absorption region 1710.

In some embodiments, the second doped regions 1712a, 1712b have a second conductivity type different from the first conductivity type of the first doped regions 1711a, 1711b. In some embodiments, the second doped regions 1712a, 1712b include a dopant. The peak concentration of the dopant of each second doped region 1712a, 1712b depends on the material of the second conductive contacts 1732a, 1732b and the material of the absorption region 1710, for example, between 1×10 ¹⁷ cm ^-3 and 5×10 ²⁰ cm ^-3 . The second doped regions 1712a, 1712b form a Schottky or Ohmic contact with the second conductive contacts 1732a, 1732b. The second doped regions 1712a and 1712b modulate the carriers generated from the absorption region 1710 based on the control of the first control signal 1772a and the second control signal 1772b.

FIG. 17F shows a cross-sectional view of a light detection device according to some embodiments. The light detection device in FIG. 17F is similar to the light detection device in FIG. 17C, and the differences are described as follows.

In some embodiments, if the isolation region 1725 is a doped region having a conductive type (e.g., N-type), the isolation region 1725 may be used to replace the first well region 1765 mentioned in FIG. 17B , and the isolation region 1725 and the second well region 1766 may be electrically connected to each other to form a short circuit structure. More precisely, in this embodiment, the conductive contact 1736 is formed on the isolation region 1725 (or on the shallow isolation region 1735), and the conductive contact 1736 and the conductive contact 1768 are electrically connected to each other (which means that the N-type doped isolation region 1725 and the second well region 1766 (e.g., P-type) are also electrically connected to each other). In this embodiment, the first well region 1765 may be omitted.

Figures 17G-17H show cross-sectional views of a light detection device according to some embodiments. The light detection device in Figures 17G-17H is similar to the light detection device in Figure 17C, and the differences are described as follows.

In some embodiments, the positions of the isolation region 1725 (with or without the shallow isolation region 1735), the first well region 1765, and the second well region 1766 can be adjusted. For example, as shown in FIG. 17G, the isolation region 1725 (which may or may not include the shallow isolation region 1735) can be disposed between the absorption region 1710 and the short circuit structure 1760. In some embodiments, the first well region 1765 is between the second well region 1766 and the isolation region 1725. In some embodiments, the first well region 1765 and the second well region 1766 are both disposed outside the annular isolation region 1725.

In some embodiments, as shown in FIG. 17H , the isolation region 1725 (which may or may not include the shallow isolation region 1735) may be disposed between the first well region 1765 and the second well region 1766. In other words, the first well region 1765 is disposed between the absorption region 1710 and the isolation region 1725. In some embodiments, the second well region 1766 is disposed between the absorption region 1710 and the isolation region 1725.

Figures 17I-17J show cross-sectional views of a light detection device according to some embodiments. The light detection device in Figures 17I-17J is similar to the light detection device in Figure 17B, and the differences are described as follows.

The light detection device in Figures 17I-17J also includes an isolation region 1725, which is similar to the isolation region 1725 described in Figure 17C. In some embodiments, the isolation region 1725 extends from the bottom surface of the substrate 1720 and extends from the bottom surface to a predetermined depth. That is, the isolation region 1725 does not penetrate the upper surface of the substrate 1720. In some embodiments, along a direction substantially parallel to the upper surface of the substrate 1720, the short-circuit structure 1760 can be closer to the absorption region 1710 than the isolation region 1725. In some embodiments, along a direction substantially parallel to the upper surface of the substrate 1720, the isolation region 1725 can be closer to the absorption region 1710 than the short-circuit structure 1760.

In some embodiments, the pixel 1700 further includes a blocking layer 1740 surrounding the absorption region 1710, wherein the conductivity type of the blocking layer (e.g., P-type) is different from the first conductivity type (e.g., N-type) of each of the first doped regions 1711a, 1711b. The blocking layer 1740 can block the photogenerated carriers in the absorption region 1710 from reaching the substrate 1720, thereby increasing the collection efficiency of the photogenerated carriers of the pixel. The blocking layer 1740 can also block the photogenerated carriers in the substrate 1720 from reaching the absorption region 1710, thereby increasing the speed of the photogenerated carriers of the pixel. The material included in the blocking layer 1740 may be the same as the material of the absorption region 1710, the same as the material of the substrate 1720, or different from the material of the absorption region 1710 and the material of the substrate 1720. In some embodiments, the shape of the blocking layer 1740 may be, but is not limited to, a ring. In some embodiments, as shown in FIG. 17J , the blocking layer 1740 may extend to the upper surface of the substrate 1720. In some embodiments, the blocking layer 1740 may overlap with the first well region 1765 and the second well region 1766 because the isolation region 1725 extends from the bottom surface of the substrate 1720 and does not penetrate the upper surface of the substrate 1720.

In some embodiments, the blocking layer 1740 is doped with a dopant having a peak concentration ranging from 10 ¹⁵ cm ^-3 to 10 ²⁰ cm ^-3 . The blocking layer 1740 can reduce crosstalk between the pixel 1700 and other adjacent pixels (not shown).

In some embodiments, the light detection device may further include a third conductive contact (not shown) electrically connected to the blocking layer 1740. The blocking layer 1740 may be biased through the third conductive contact to release carriers that are not collected by the first doped regions 1711a, 1711b.

Please refer to Figures 17K, 17L and 17M. Figures 17K-17M show a top view of a light detection device according to some embodiments. In some embodiments, the light detection device includes a plurality of pixels 1700, i.e., a pixel array including a plurality of repeated pixels. In some embodiments, the pixel array may be a one-dimensional or two-dimensional pixel array. Each pixel is a photodetector, and the embodiments disclosed above may be used. Referring to the layout shown in Figures 17K and 17L, the pixels 1700 may be arranged in a staggered layout, wherein the width and length of each pixel are arranged in a direction perpendicular to the width and length of adjacent pixels. As shown in Figure 17M, the pixels 1700 may be arranged in an inclined direction (e.g., arranged at 45 degrees). The pixel layout shown in Figures 17K-17M may bring the advantage of reduced pixel spacing.

In addition, in some of the above embodiments (such as the embodiments mentioned in Figures 17B-17H), the short-circuit structure 1760 includes a first well region 1765 and a second well region 1766 connected to each other. However, in some embodiments, the short-circuit structure 1760 may also include a first well region 1765 and two second well regions 1766 connected to each other, and the first well region 1765 is disposed between the two second well regions 1766.

In addition, as described above, in some embodiments, each pixel 1700 may include more than one short-circuit structure 1760, as shown in FIG. 17K, FIG. 17L, and FIG. 17M, each pixel 1700 includes two short-circuit structures 1760.

In FIG. 17K , the two short-circuit structures 1760 are arranged symmetrically along the long axis of the absorption region 1710. In other words, the two short-circuit structures 1760 are arranged beside the two long sides of the absorption region 1710.

In FIG. 17L , the two short-circuit structures 1760 are arranged symmetrically along the short axis of the absorption region 1710. In other words, the two short-circuit structures 1760 are arranged beside the two short sides of the absorption region 1710.

In FIG. 17M, the pixels 1700 may be arranged along an inclined direction (e.g., arranged at 45 degrees). As an example, the two short-circuit structures 1760 are arranged symmetrically along the short axis of the absorption region 1710. However, in other embodiments, the two short-circuit structures 1760 may also be arranged symmetrically along the long axis of the absorption region 1710.

In some of the above embodiments, each switch 1790 includes a control area 1791 and a readout area 1792, and the control area 1791 may include different components disposed therein. In the present disclosure, the control area 1791 may include different components to form different embodiments.

FIG. 17N shows a schematic diagram of a cross-sectional structure of a control region 1791 in three different embodiments of the present disclosure. In some embodiments, referring to the left side of FIG. 17O , a second conductive contact 1732a is disposed on the upper surface of the absorption region 1710. This structure is similar to that shown in FIG. 17A and will not be described again.

In some embodiments, referring to the middle of FIG. 17O , in addition to the second conductive contact 1732a, the control region 1791 further includes a second doping region 1712a disposed below the second conductive contact 1732a. This structure is similar to the structure shown in FIG. 17E and will not be described again.

In some embodiments, referring to the right side of FIG. 17O , in addition to the second conductive contact 1732a and the second doped region 1712a, the control region 1791 further includes a dielectric layer 1733 disposed between the second conductive contact 1732a and the second doped region 1712a. The dielectric layer 1733 prevents current from being conducted directly from the second conductive contact 1732a to the absorption region, but applying a voltage to the second conductive contact 1732a allows an electric field to be established in the absorption region. The established electric field can attract or repel electric carriers in the absorption region.

In some embodiments, the light detection device described in FIGS. 16A to 16Q may further include a short circuit structure 1760. Taking the light detection device described in FIG. 16E as an example, the light detection device may further include a short circuit structure, which includes a first well region and a second well region in the substrate 1620. In some embodiments, the short circuit structure is located between the isolation region 1650 and one of the sub-pixels 1600a, 1600b. In some embodiments, the isolation region 1650 is located between the short circuit structure and one of the sub-pixels 1600a, 1600b.

In some embodiments, the light detection device described in Figures 16A to 16Q may also include multiple short-circuit structures 1760. In some embodiments, each short-circuit structure is located between one of the outermost sub-pixels and the isolation region. In some embodiments, the isolation region is between the short-circuit structure and the outermost sub-pixel. Taking the light detection device described in Figure 16E as an example, the light detection device may also include two short-circuit structures in the substrate 1620. In some embodiments, the two short-circuit structures are located between the respective sub-pixels 1600a, 1600b and the isolation region 1650. In some embodiments, the isolation region is between the short-circuit structure and the corresponding sub-pixel 1600a, 1600b.

FIG18 is a block diagram of an example embodiment of an imaging system. The imaging system may include an imaging module and a software module configured to reconstruct a 3D model of a detected object. The imaging system or imaging module may be used in a mobile device (e.g., a smartphone, a tablet, a vehicle, a drone, etc.), or in an auxiliary device for a mobile device (e.g., a wearable device), a computing system on a vehicle or in a fixed facility (e.g., a factory), a robotic system, a surveillance system, or any other suitable device and/or system.

The imaging module includes an emitter unit, a receiver unit, and a controller. During operation, the emitter unit may emit incident light toward a target object. The receiver unit may receive reflected light reflected from the target object. The controller may drive at least the emitter unit and the receiver unit. In some implementations, the receiver unit and the controller are located on a semiconductor chip, such as a system-on-a-chip (SoC). In some cases, the emitter unit includes two different semiconductor chips, such as a laser emitter chip on a III-V substrate, and a silicon laser driver chip on a silicon substrate.

The emitter unit may include one or more light sources, control circuitry for controlling the one or more light sources, and/or an optical structure for manipulating light emitted from the one or more light sources. In some embodiments, the light source may include one or more light emitting diodes or vertical-cavity surface-emitting lasers (VCSELs), which emit light that can be absorbed by an absorption region in the light detection device. For example, one or more light emitting diodes or vertical-cavity surface-emitting lasers can emit light with a peak wavelength in the visible wavelength range (e.g., a wavelength visible to the human eye), such as 570 nanometers, 670 nanometers, or any other applicable wavelength. As another example, one or more LEDs or VCSELs can emit light having a peak wavelength above the visible wavelength range, such as 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm, 1550 nm, or any other applicable wavelength.

In some embodiments, incident light from a light source may be collimated by one or more optical structures. For example, the optical structure may include one or more collimating lenses.

The receiver unit may include one or more light detection devices according to any of the above embodiments. The receiver unit may also include a control circuit for controlling the control circuit and/or the optical structure to manipulate the light reflected from the target object toward the one or more light detection devices. In some embodiments, the optical structure includes one or more lenses that receive collimated light and focus the collimated light to the one or more light detection devices.

In some embodiments, the controller includes a timing generator and a processing unit. The timing generator receives a reference timer signal and provides a timing signal to the transmitter unit for modulating the emitted light. The timer signal is also provided to the receiver unit for controlling the collection of photocarriers. The processing unit processes the photocarriers generated and collected by the receiver unit and determines the raw data of the target object. The processing unit may include a control circuit, one or more signal processors for processing information output from the light detection device, and/or a computer storage medium that can store instructions for determining the raw data of the target object or store the raw data of the target object. For example, a controller in an indirect time-of-flight (i-ToF) sensor determines the distance between two points by using the phase difference between the light emitted by the transmitter unit and the light received by the receiver unit.

The software module can be implemented to run in applications such as facial recognition, eye tracking, gesture recognition, stereo model scanning/video recording, motion tracking, autonomous vehicles, and/or augmented/virtual reality.

FIG19 shows a block diagram of an example receiver unit or controller. Here, an array of image sensors (e.g., 240×180) can be implemented using any implementation of the light detection device described with reference to FIGS. 3A to 8E, 14C to 14L. A phase-locked loop (PLL) circuit (e.g., an integer-N PLL) can generate timer signals (e.g., a four-phase system clock) for modulation and demodulation. These timer signals can be gate-controlled and/or adjusted by a timing generator for preset integration times and different operating modes before being sent to the pixel array and external lighting driver. A programmable delay line can be added in the lighting driver path to delay the timer signal.

Voltage regulators can be used to control the operating voltage of image sensors. For example, image sensors can use multiple voltage domains. Temperature sensors can be implemented for possible uses such as depth calibration and power control.

The readout circuitry of the light detection device bridges each photodetection element of the image sensor array to an array of analog-to-digital converters (ADCs), where the output of the analog-to-digital converters can be further processed and integrated in the digital domain by a signal processor before reaching the output interface. Memory can be used to store the output of the signal processor. In some embodiments, the output interface can be implemented using a 2-lane, 1.2GB/s PHY-MIPI transmitter, or using CMOS outputs for low-speed/low-cost systems.

An inter-integrated circuit (I2C) interface can be used to access all functional blocks described here.

In the present disclosure, if not specifically mentioned, the absorption region may be completely embedded in the substrate, partially embedded in the substrate, or completely on the first surface of the substrate. Similarly, if not specifically mentioned, the germanium-based light absorbing material may be completely embedded in the semiconductor substrate, partially embedded in the semiconductor substrate, or completely on the first surface of the semiconductor substrate.

In the present disclosure, if not specifically mentioned, the absorption region may be configured to absorb photons with a peak wavelength in the non-visible wavelength range of not less than 800 nm, such as 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm or 1550 nm. In some embodiments, the non-visible wavelength range does not exceed 2000 nm. In some embodiments, the absorption region receives an optical signal and converts the optical signal into an electrical signal.

x

1，0

y

1。在一些實施例中，吸收區域包括Ge_1-aSn_a，其中0

a

0.1。在一些實施例中，基底包括矽。在一些實施例中，基底由矽組成。在一些實施例中，吸收區域由鍺、矽或鍺矽(Ge_xSi_1-x)組成。在一些實施例中，由於在吸收區域形成期間形成的材料缺陷，由本徵鍺組成的吸收區域為P型，其中缺陷密度為1x 10¹⁴cm^-3至1x 10¹⁶cm^-3。 In the present disclosure, if not specifically mentioned, the substrate is made of a first material or a first material composite. The absorption region is made of a second material or a second material composite. The second material or the second material composite is different from the first material or the first material composite. In some embodiments, the absorption region includes a semiconductor material. In some embodiments, the absorption region includes a polycrystalline material. In some embodiments, the substrate includes a semiconductor material. In some embodiments, the absorption region includes a III-V semiconductor material. In some embodiments, the substrate includes a III-V semiconductor material. The III-V semiconductor material may include but is not limited to gallium arsenide/aluminum arsenide (GaAs/AlAs), indium phosphide/indium gallium arsenide (InP/InGaAs), gallium asbide/indium arsenide (GaSb/InAs), or indium asbide (InSb). In some embodiments, the absorption region includes a semiconductor material containing a Group IV element. For example, germanium, silicon or tin. In some embodiments, the absorption region comprises Ge _x Si _1-x , where 0<x<1. In some embodiments, the absorption region comprises Si _x Ge _y Sn _1-xy , where 0

x

1,0

y

1. In some embodiments, the absorption region includes Ge _1-a Sn _a , where 0

a

0.1. In some embodiments, the substrate includes silicon. In some embodiments, the substrate is composed of silicon. In some embodiments, the absorption region is composed of germanium, silicon, or germanium silicon ( _{GexSi1 -x} ). In some embodiments, due to material defects formed during the formation of the absorption region, the absorption region composed of intrinsic germanium is p-type, wherein the defect density is 1x ¹⁰¹⁴ cm ^-3 to 1x ¹⁰¹⁶ cm ^-3 .

In the present disclosure, if not specifically mentioned, the absorption region has a thickness that depends on the wavelength of the photons to be detected and the material of the absorption region. In some embodiments, when the absorption region includes germanium and is designed to absorb photons with a wavelength of not less than 800 nanometers, the absorption region has a thickness of not less than 0.1um. In some embodiments, the absorption region includes germanium and is designed to absorb photons with a wavelength between 800 nanometers and 2000 nanometers, and the absorption region has a thickness between 0.1um and 2.5um. In some embodiments, for higher quantum efficiency, the thickness of the absorption region is between 1um and 2.5um. In some embodiments, blanket epitaxy, selective epitaxy, or other applicable techniques can be used to grow the absorption region.

In the present disclosure, if not specifically mentioned, the first readout circuit, the second readout circuit, the first common readout circuit or the second common readout circuit may be a three-transistor configuration consisting of a reset gate, a source follower and a selection gate, or a circuit including four or more transistors, or any suitable circuit for processing charge. In some embodiments, the first readout circuit and the second readout circuit may be fabricated on a substrate. In some other embodiments, the first readout circuit and the second readout circuit may be fabricated on another substrate and integrated/co-packaged with the absorption region by die/wafer bonding or stacking. In some embodiments, the light detection device includes a bonding layer (not shown) between the readout circuit and the absorption region. The bonding layer may comprise any suitable material, such as an oxide or a semiconductor or a metal or an alloy.

In the present disclosure, if not specifically mentioned, the first readout circuit includes a first capacitor. The first capacitor is configured to store photocarriers collected by one of the first doped regions. In some embodiments, the first capacitor is electrically coupled to a reset gate of the first readout circuit. In some embodiments, the first capacitor is located between a source follower of the first readout circuit and the reset gate of the first readout circuit. In some embodiments, the second readout circuit includes a second capacitor. In some embodiments, the second capacitor is configured to store photocarriers collected by another first doped region. In some embodiments, the second capacitor is electrically coupled to a reset gate of the second readout circuit. In some embodiments, the second capacitor is located between the source follower of the second readout circuit and the reset gate of the second readout circuit. Examples of the first capacitor and the second capacitor include but are not limited to floating-diffusion capacitors, metal oxide metal capacitors, metal insulator metal capacitors, and metal oxide semiconductor capacitors.

In the present disclosure, if not specifically mentioned, in the same pixel, the type of carriers collected by the first doped region of one switch and the type of carriers collected by the first doped region of another switch are the same. For example, when the light detection device is configured to collect electrons, when the first switch is turned on and the second switch is turned off, the first doped region in the first switch collects electrons of photocarriers generated from the absorption region, and when the second switch is turned on and the first switch is turned off, the first doped region in the second switch also collects electrons of photocarriers generated from the absorption region.

In some embodiments, the first dielectric layer and the second dielectric layer in the present disclosure include but are not limited to silicon dioxide. In some embodiments, the first dielectric layer, the second dielectric layer, the third dielectric layer, the fourth dielectric layer and the fifth dielectric layer include high-k materials, including but not limited to silicon nitride (Si ₃ N ₄ ), silicon oxynitride (SiON), silicon nitride (SiNx), silicon oxide (SiOx), germanium oxide (GeOx), aluminum oxide (Al ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), titanium dioxide (TiO ₂ ), helium dioxide (HfO ₂ ) or zirconium dioxide (ZrO ₂ ). In some embodiments, the first dielectric layer, the second dielectric layer, the third dielectric layer, the fourth dielectric layer, and the fifth dielectric layer in the present disclosure include semiconductor materials, but are not limited to amorphous silicon, polysilicon, crystalline silicon, or a combination thereof.

In the present disclosure, if not specifically mentioned, the first conductive contact, the second conductive contact, and the third conductive contact include metal or alloy. For example, the first conductive contact, the second conductive contact, and the third conductive contact include aluminum, copper, tungsten, titanium, Ta-TaN-Cu stack or Ti-TiN-W stack.

Although the present disclosure has been described by way of example and according to preferred embodiments, it should be understood that the present disclosure is not limited thereto. Rather, it is intended to describe various modifications and similar arrangements and processes, and the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and processes.

The above is only the preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

1600: Pixels

1600a: Sub-pixel

1600b: Sub-pixel

1610: Absorption area

1611a: First doping region

1611b: First doping region

1613: Detection area

1620: Base

1631a: First conductive contact

1631b: First conductive contact

1632a: Second conductive contact

1632b: Second conductive contact

1660:Shade layer

1661: Open

1671a: First readout circuit

1671b: Second readout circuit

1672a: First control signal

1672b: Second control signal

Claims (17)

A light detection device comprises: a pixel, the pixel comprising: N sub-pixels, wherein each sub-pixel comprises a detection region and two first conductive contacts, wherein each of the detection regions is located between the two first conductive contacts, wherein each of the sub-pixels further comprises two first doped regions located under the corresponding first conductive contacts, wherein each of the first doped regions has a first conductive type, and wherein N is a positive integer and

2; and an isolation region surrounding the detection regions of the N sub-pixels, wherein, in a cross section through the pixel, a minimum width between the first conductive contacts of the two adjacent sub-pixels is smaller than a width of the isolation region. A light detection device as described in claim 1, wherein each of the sub-pixels further comprises two second conductive contacts, wherein the detection region is located between the two second conductive contacts. A light detection device as described in claim 1, wherein each sub-pixel further includes two second doped regions located under two corresponding second conductive contacts, and each of the second doped regions has a second conductive type, and the first conductive type is different from the second conductive type. A light detection device as described in claim 1, wherein the pixel further includes an absorption region, wherein the detection regions of the N sub-pixels are located in the same absorption region. A light detection device as described in claim 4, wherein from a cross-sectional view of the light detection device, a minimum width between the first conductive contacts contained in each of two adjacent sub-pixels is smaller than a width of the absorption region. The light detection device as described in claim 3, wherein the pixel further includes an absorption region, wherein the first doped region and the second doped region of the N sub-pixels are located in the same absorption region. A light detection device as described in claim 6, wherein the pixel further includes a blocking layer surrounding the absorption region, wherein a conductivity type of the blocking layer is different from the first conductivity type contained in each of the first doped regions. A light detection device as described in claim 1, wherein the isolation region is outside the detection region and is physically separated from the absorption region. A light detection device as described in claim 3, wherein the pixel further includes a third doped region between the two adjacent sub-pixels in the N sub-pixels, and the third doped region is separated from the first doped regions of the two adjacent sub-pixels, wherein the third doped region has a conductivity type different from the first conductivity type. A light detection device as described in claim 3, wherein one of the sub-pixels further includes a reverse doped region overlapping with a portion of one of the first doped regions of the sub-pixel, wherein the reverse doped region has a conductivity type different from the first conductivity type. A light detection device as described in claim 2, wherein the pixel includes 2N readout circuits and 2N control signals, two of the readout circuits are electrically coupled to the first conductive contact of one of the sub-pixels, and two of the control signal circuits are electrically coupled to the second conductive contact of one of the sub-pixels. A light detection device as described in claim 1, wherein the pixel includes a common readout circuit, wherein the common readout circuit is electrically coupled to one of the first conductive contacts of one of the sub-pixels, and is electrically coupled to one of the first conductive contacts of another of the sub-pixels. A light detection device as described in claim 2, wherein the pixel includes a common control signal, wherein the common control signal is electrically coupled to one of the second conductive contacts of one of the sub-pixels, and electrically coupled to one of the second conductive contacts of another of the sub-pixels. A light detection device as described in claim 1, wherein the light detection device further comprises a plurality of optical elements located on each of the sub-pixels. A light detection device comprises: a first pixel, and a second pixel adjacent to the first pixel, wherein each of the first pixel and the second pixel comprises: N detection regions; 2N first conductive contacts, each coupled to one of the detection regions; and 2N second conductive contacts, each coupled to one of the detection regions, wherein N is a positive integer, and

2; and an isolation region between the first pixel and the second pixel, wherein, in a cross section through the light detection device, a minimum width between one of the 2N first conductive contacts of the first pixel and one of the 2N first conductive contacts of the second pixel is smaller than a width of the isolation region. An imaging system, comprising: an emitter unit capable of emitting light; and a receiver unit including an image sensor, comprising: a light detection device, comprising: a plurality of pixels, wherein each pixel comprises: N sub-pixels, wherein each sub-pixel comprises a detection region and two first conductive contacts, wherein the detection region is located between the two first conductive contacts, and the detection region is configured to absorb a photon having a specific wavelength and generate a photocarrier from the absorbed photon, wherein N is a positive integer and

2; and an isolation region surrounding the detection regions of the N sub-pixels, wherein, in a cross section through the pixel, a minimum width between the first conductive contacts of the two adjacent sub-pixels is smaller than a width of the isolation region. The imaging system of claim 16 further comprises a processing unit capable of processing photocarriers generated by the receiver unit.

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