Light detection device and electronic apparatus

Abstract

Provided is a light detection device capable of achieving desired pixel characteristics while suppressing generation of dark current. Specifically, the light detection device is provided with a semiconductor substrate, a plurality of photoelectric conversion units formed in a two-dimensional array on the semiconductor substrate, and an inter-pixel separation structure formed in a region between the photoelectric conversion units of the semiconductor substrate. The inter-pixel separation structure includes a first inter-pixel separation structure that is a portion in an effective pixel region, and a second inter-pixel separation structure that is a portion in a light-shielding pixel region that surrounds the periphery of the effective pixel region. A first conductor is disposed in the first inter-pixel separation structure, and a second conductor electrically connected to the first conductor and to which a negative bias voltage is applied is disposed in the second inter-pixel separation structure. Further, the first conductor and the second conductor are formed using different conductive materials.

Description

Photodetector and electronic equipment

[0001] The present technology (technology according to the present disclosure) relates to a light detection device and an electronic device.

[0002] Conventionally, for example, a photodetector has been proposed that includes a semiconductor substrate having a plurality of photoelectric conversion units, a trench portion formed in a region between the photoelectric conversion units of the semiconductor substrate, and an inter-pixel isolation structure having a conductor disposed in the trench portion (see, for example, Patent Document 1). In the photodetector described in Patent Document 1, a negative bias voltage is applied to the conductor to create a high hole concentration state in the periphery of the inter-pixel isolation structure, thereby suppressing the generation of dark current.

[0003] Japanese Patent Application Laid-Open No. 2022-148841

[0004] In such a photodetector, it is required to suppress the generation of dark current and also to be able to realize desired pixel characteristics.

[0005] An object of the present disclosure is to provide a photodetector and electronic equipment that can achieve desired pixel characteristics while suppressing the generation of dark current.

[0006] The photodetector device disclosed herein comprises (a) a semiconductor substrate, (b) a plurality of photoelectric conversion units formed in a two-dimensional array on the semiconductor substrate, and (c) an inter-pixel isolation structure formed in a region between the photoelectric conversion units on the semiconductor substrate, (d) the inter-pixel isolation structure has a first inter-pixel isolation structure that is a portion within an effective pixel region and a second inter-pixel isolation structure that is a portion within a light-shielded pixel region that surrounds the effective pixel region, (e) a first conductor is arranged within the first inter-pixel isolation structure, (f) a second conductor that is electrically connected to the first conductor and to which a negative bias voltage is applied is arranged within the second inter-pixel isolation structure, and (g) the first conductor and the second conductor are formed using different conductive materials.

[0007] The electronic device of the present disclosure includes (a) a semiconductor substrate, (b) a plurality of photoelectric conversion units formed in a two-dimensional array on the semiconductor substrate, (c) an inter-pixel isolation structure formed in a region between the photoelectric conversion units on the semiconductor substrate, (d) the inter-pixel isolation structure includes a first inter-pixel isolation structure that is a portion within an effective pixel region and a second inter-pixel isolation structure that is a portion within a light-shielded pixel region that surrounds the effective pixel region, (e) a first conductor is disposed within the first inter-pixel isolation structure, (f) a second conductor that is electrically connected to the first conductor and to which a negative bias voltage is applied is disposed within the second inter-pixel isolation structure, and (g) a photodetector is provided in which the first conductor and the second conductor are formed using conductive materials that are different from each other.

[0008] 10 is a diagram showing the overall configuration of a solid-state imaging device according to a first embodiment; FIG. 11 is a diagram showing the planar configuration of one of the four corners of a pixel region; FIG. 12 is a diagram showing the cross-sectional configuration of the solid-state imaging device when cut along line A-A in FIG. 2; FIG. 13 is a diagram showing the cross-sectional configuration of the solid-state imaging device when cut along line B-B in FIG. 2; FIG. 14 is a diagram showing a method for manufacturing a solid-state imaging device; FIG. 15 is a diagram showing a method for manufacturing a solid-state imaging device; FIG. 16 is a diagram showing a method for manufacturing a solid-state imaging device; FIG. 17 is a diagram showing the planar configuration of one of the four corners of a pixel region 2 of a solid-state imaging device according to a second embodiment; FIG. 18 is a diagram showing the cross-sectional configuration of a solid-state imaging device according to a second embodiment when cut along line C-C in FIG. 10; FIG. 19 is a diagram showing the cross-sectional configuration of a solid-state imaging device according to a third embodiment when cut along line A-A in FIG. 2; FIG. 20 is a diagram showing the cross-sectional configuration of a solid-state imaging device according to a third embodiment when cut along line B-B in FIG. 2; FIG. 19 is a diagram showing the schematic configuration of an electronic device according to a fourth embodiment; FIG. 21 is a diagram showing an example of the schematic configuration of an endoscope system. Fig. 17 is a block diagram showing an example of the functional configuration of the camera and the CCU shown in Fig. 16. Fig. 18 is a diagram showing an example of the schematic configuration of a microsurgery system.

[0009] Examples of a photodetector and an electronic device according to an embodiment of the present disclosure will be described below with reference to FIGS. 1 to 18. The embodiments of the present disclosure will be described in the following order. Note that the present disclosure is not limited to the following examples. Furthermore, the effects described in this specification are examples and are not limiting, and other effects may also be present.

[0010] 1. First embodiment: solid-state imaging device 1-1 Overall configuration of solid-state imaging device 1-2 Configuration of main parts 1-3 Method for manufacturing solid-state imaging device 2. Second embodiment: solid-state imaging device 2-1 Configuration of main parts 3. Third embodiment: solid-state imaging device 3-1 Configuration of main parts 3-2 Modifications 4. Fourth embodiment: Application to electronic devices 5. Fifth embodiment: Application to mobile objects

[0011] 1. First Embodiment 1-1 Overall Configuration of Solid-State Imaging Device A solid-state imaging device 1 (or, more broadly, a "photodetector") according to a first embodiment of the present disclosure will be described. FIG. 1 is a diagram illustrating the overall configuration of the solid-state imaging device 1 according to the first embodiment. The solid-state imaging device 1 of FIG. 1 is a back-illuminated CMOS (Complementary Metal Oxide Semiconductor) image sensor. As shown in FIG. 15, the solid-state imaging device 1 (1002) captures image light (incident light) from a subject via a lens group 1001, converts the amount of incident light focused on the imaging surface into an electrical signal on a pixel-by-pixel basis, and outputs the electrical signal as a pixel signal. As shown in FIG. 1, the solid-state imaging device 1 includes a pixel region 2, a vertical drive circuit 3, a column signal processing circuit 4, a horizontal drive circuit 5, an output circuit 6, and a control circuit 7.

[0012] The pixel region 2 includes a plurality of pixels 8 arranged in a two-dimensional array. Each pixel 8 includes a photoelectric conversion unit PD (see FIG. 3 ) and a plurality of pixel transistors (e.g., a transfer transistor, a reset transistor, an amplification transistor, and a selection transistor). As shown in FIG. 2 , the pixel region 2 includes an effective pixel region 12 and a light-shielding pixel region 13 surrounding the effective pixel region 12. The light-shielding pixel region 13 includes light-shielding pixels such as OPB (Optical Black) pixels for obtaining a reference signal for an optical black level and dummy pixels. The vertical drive circuit 3 is configured, for example, by a shift register. It sequentially selects each pixel 8 in the pixel region 2 row by row by, for example, outputting selection pulses to pixel drive wiring 9, and outputs pixel signals of the selected pixels 8 to the column signal processing circuit 4 via vertical signal lines 10. Examples of pixel signals include signals obtained from charges (e.g., electrons) generated by the photoelectric conversion unit PD.

[0013] The column signal processing circuits 4 are arranged, for example, for each column of pixels 8, and perform signal processing such as noise removal on signals output from one row of pixels 8 for each pixel column. For example, correlated double sampling (CDS) for removing fixed pattern noise specific to pixels and analog-to-digital (AD) conversion can be used as the signal processing. The horizontal drive circuit 5 is configured, for example, with a shift register, and sequentially outputs horizontal scanning pulses to the column signal processing circuits 4, selects the column signal processing circuits 4 in turn, and causes the selected column signal processing circuit 4 to output the processed pixel signals to the horizontal signal line 11.

[0014] The output circuit 6 performs signal processing on pixel signals sequentially output from each column signal processing circuit 4 via the horizontal signal line 11 and outputs the processed signals. Examples of signal processing that can be used include various digital signal processing techniques such as buffering, black level adjustment, and column variation correction. For example, black level adjustment can be performed by subtracting an optical black level reference signal obtained from pixels 8 (OPB pixels) in the light-shielded pixel region 13 from pixel signals obtained from pixels 8 (effective pixels) in the effective pixel region 12, thereby correcting the black level of the pixel signals to "0." The control circuit 7 generates clock signals and control signals that serve as references for the operation of the vertical drive circuit 3, column signal processing circuit 4, horizontal drive circuit 5, etc., based on a vertical synchronization signal, a horizontal synchronization signal, and a master clock signal (not shown). The control circuit 7 then outputs the generated clock signals and control signals to the vertical drive circuit 3, column signal processing circuit 4, horizontal drive circuit 5, etc.

[0015] [1-2 Configuration of Main Parts] Next, the detailed structure of the solid-state imaging device 1 will be described. FIG. 2 is a diagram showing the planar configuration of one of the four corners of the pixel region 2. In FIG. 2, the structure above the light-shielding metals 18, 19 is omitted so that the light-shielding metals 18, 19 can be clearly seen. FIG. 3 is a diagram showing the cross-sectional configuration of the solid-state imaging device 1 taken along line A-A in FIG. 2. Note that FIG. 3 illustrates a case in which pupil correction is performed to shift the position of the light-shielding metal 18 toward the center of the pixel region 2 (the lower side in FIG. 3), and the photoelectric conversion unit PD is located below the light-shielding metal 18. FIG. 4 is a diagram showing the cross-sectional configuration of the solid-state imaging device 1 taken along line B-B in FIG. 2. As shown in FIG. 2, the pixel region 2 has an effective pixel region 12 located at the center of the pixel region 2 and a light-shielding pixel region 13 surrounding the effective pixel region 12. The effective pixel region 12 is the area in which an object is captured. As shown in FIG. 3 , in the effective pixel region 12, the solid-state imaging device 1 includes a semiconductor substrate 14. An insulator 15, a first conductor 16, an insulating film 17, and a light-shielding metal 18 are stacked in this order on the light-receiving surface (hereinafter referred to as the “back surface S1” or, in a broader sense, the “first surface”) of the semiconductor substrate 14. Although nothing is shown on the light-receiving surface (hereinafter referred to as the “back surface S2”) side of the light-shielding metal 18a in FIG. 3 , a color filter, an on-chip lens, or the like may be formed thereon. A wiring layer 20 is disposed on the surface (hereinafter referred to as the “front surface S3” or, in a broader sense, the “second surface”) of the semiconductor substrate 14 opposite the back surface S1. The light-shielding pixel region 13 is a region surrounding the effective pixel region 12. In the light-shielding pixel region 13, the solid-state imaging device 1 includes a semiconductor substrate 14 shared with the effective pixel region 12. A light-shielding metal 19 is disposed on the back surface S1 of the semiconductor substrate 14. In addition, a wiring layer 20 is disposed on the surface S3 of the semiconductor substrate 14.

[0016] The semiconductor substrate 14 is a substrate made of, for example, silicon (Si). The semiconductor substrate 14 is shared by the effective pixel region 12 and the light-shielding pixel region 13, and a photoelectric conversion unit PD is formed in each region corresponding to each pixel 8. That is, multiple photoelectric conversion units PD are formed in a two-dimensional array on the semiconductor substrate 14. The photoelectric conversion units PD form photodiodes with p-type and n-type semiconductor regions at p-n junctions, and photoelectrically convert incident light to generate electric charges. The generated electric charges are stored in electrostatic capacitance generated by the p-n junctions. Furthermore, inter-pixel isolation structures 21 are formed on the semiconductor substrate 14 in regions between the photoelectric conversion units PD. That is, the inter-pixel isolation structures 21 are formed in a lattice pattern so as to surround each photoelectric conversion unit PD. The inter-pixel isolation structure 21 also includes a first inter-pixel isolation structure 22 that is a portion within the effective pixel region 12 and a second inter-pixel isolation structure 23 that is a portion within the light-shielding pixel region 13. The first inter-pixel isolation structure 22 is formed from the back surface S1 of the semiconductor substrate 14 to partway between the back surface S1 and the front surface S3. Furthermore, a first conductor 16 is arranged in the first inter-pixel isolation structure 22 from the back surface S1 to partway between the back surface S1 and the front surface S3. Specifically, the first inter-pixel isolation structure 22 has a trench portion 24, and an insulator 15 and a first conductor 16 arranged in the trench portion 24. The trench portion 24 is formed from the back surface S1 of the semiconductor substrate 14 to partway between the back surface S1 and the front surface S3, and its sidewall surface and bottom surface form the outline of the first inter-pixel isolation structure 22. Furthermore, the insulator 15 continuously covers the sidewall surface of the trench portion 24 and the back surface S1 of the semiconductor substrate 14 in the effective pixel region 12. The insulator 15 is formed on the rear surface S1 side of the semiconductor substrate 14 up to the boundary between the effective pixel region 12 and the light-shielding pixel region 13 so that the insulator 15 does not cover the rear surface S1 of the light-shielding pixel region 13. The material (insulating material) of the insulator 15 may be, for example, silicon oxide (SiO).

[0017] The first conductor 16 is embedded in the space within the trench portion 24, i.e., the space between the sidewall surfaces covered with the insulator 15. This electrically integrates each portion of the first conductor 16 within the trench portion 24. The first conductor 16 is disposed from the back surface S1 of the semiconductor substrate 14 to the bottom surface of the trench portion 24. The first conductor 16 also covers the space within the trench portion 24, as well as the region (grid-like region) between the photoelectric conversion units PD on the light-receiving surface (hereinafter also referred to as the "back surface S6") of the insulator 15 located on the back surface S1 of the semiconductor substrate 14. That is, the first conductor 16 is disposed continuously within the first inter-pixel isolation structure 22 and in the region between the photoelectric conversion units PD on the back surface S1 of the semiconductor substrate 14 within the effective pixel region 12. The formation range of the first conductor 16 on the back surface S6 side of the insulator 15 extends to the boundary between the effective pixel region 12 and the light-shielded pixel region 13 so as not to reach the light-shielded pixel region 13. A conductive material, such as indium tin oxide (ITO), can be used as the material of the first conductor 16. Between the end of the first inter-pixel isolation structure 22 on the surface S3 side and the surface S3 of the semiconductor substrate 14, an STI 50 is formed in a lattice pattern along the first inter-pixel isolation structure 22.

[0018] The second pixel isolation structure 23 is formed to penetrate the semiconductor substrate 14 from the back surface S1 to the front surface S3 of the semiconductor substrate 14. A conductor (hereinafter also referred to as a "second conductor 25") is disposed within the second pixel isolation structure from the back surface S1 to the front surface S3. Specifically, the second pixel isolation structure 23 includes a trench portion 26, and an insulator 27 and a second conductor 25 disposed within the trench portion 26. The trench portion 26 penetrates the semiconductor substrate 14 from the back surface S1 to the front surface S3 of the semiconductor substrate 14, and its sidewall surfaces form the outer shape of the second pixel isolation structure 23. The insulator 27 continuously covers the sidewall surfaces of the trench portion 26. Silicon oxide (SiO) can be used as a material for the insulator 27, for example. The second conductor 25 is embedded in the space within the trench portion 26, i.e., the space between the sidewall surfaces covered with the insulator 27. As a result, each portion of the second conductor 25 in the trench portion 26 is electrically integrated. Furthermore, the space between the sidewall surfaces covered with the insulator 27 (i.e., the space within the second inter-pixel isolation structure 23) and the space between the insulators 15 within the first inter-pixel isolation structure 22 are connected to each other, and the second conductor 25 and the first conductor 16 are electrically connected by contacting their ends. Furthermore, the second conductor 25 is disposed so as to penetrate the semiconductor substrate 14 from the back surface S1 to the front surface S3 of the semiconductor substrate 14. By penetrating the semiconductor substrate 14, the second conductor 25 is exposed on both the front surface S3 and the back surface S1 of the semiconductor substrate 14. Furthermore, the second conductor 25 can be made of any conductive material. For example, doped polysilicon doped with boron (B) or the like can be used. That is, in the first embodiment, the first conductor 16 and the second conductor 25 are formed using different conductive materials. More specifically, the first conductor 16 is formed of a conductive material having a lower light absorption rate than the second conductor 25. The relationship between the light absorption rate of ITO and the light absorption rate of doped polysilicon is: light absorption rate of ITO < light absorption rate of doped polysilicon.

[0019] Furthermore, the second conductor 25 has its surface S3 side electrically connected to a negative bias voltage supply source, and a negative bias voltage is applied from the surface S3 side. By applying the negative bias voltage, the peripheral portion of the second inter-pixel isolation structure 23 in the light-shielded pixel region 13 can be made to have a high hole concentration, thereby suppressing the generation of dark current. FIG. 3 illustrates an example in which a contact 28 formed on a portion of the second conductor 25 on the surface S3 side is connected to the second conductor 25, and the second conductor 25 is connected to the negative bias voltage supply source via the contact 28. The insulating film 17 is formed to continuously cover the light-receiving surface (hereinafter also referred to as the "rear surface S4") of the first conductor 16 and a portion of the rear surface S6 of the insulator 15 where the first conductor 16 is not present.

[0020] The light-shielding metal 18 is disposed on the light-receiving surface (hereinafter also referred to as the "back surface S5") of the insulating film 17 in the effective pixel region 12, and is formed to cover the region of the insulating film 17 on the back surface S5 between the photoelectric conversion units PD in the effective pixel region 12. The light-shielding metal 19 is disposed on the back surface S1 of the semiconductor substrate 14 in the light-shielding pixel region 13, and is formed to cover the entire back surface S1 of the semiconductor substrate 14 in the light-shielding pixel region 13. The surface (hereinafter also referred to as the "front surface S7") of the light-shielding metal 19 facing the back surface S1 of the semiconductor substrate 14 is in contact with and electrically connected to the second conductor 25 exposed on the back surface S1 of the semiconductor substrate 14 (i.e., the end of the second conductor 25 on the back surface S1 side). The end of the light-shielding metal 19 on the effective pixel region 12 side is in contact with and electrically connected to the end of the portion of the first conductor 16 located on the back surface S1 on the light-shielding pixel region 13 side. As a result, the first conductor 16 and the second conductor 25 are electrically connected to each other via the light-shielding metal 19. Therefore, a negative bias voltage applied to the second conductor 25 from the surface S3 side is applied to the first conductor 16 via the second conductor 25 and the light-shielding metal 19. That is, a transmission path for the negative bias voltage is formed using the light-shielding metal 19 used to shield the photoelectric conversion unit PD in the light-shielding pixel region 13. Therefore, in the effective pixel region 12, the periphery of the first inter-pixel isolation structure 22 can be made into a high hole concentration state, thereby suppressing the generation of dark current. Examples of materials that can be used for the light-shielding metals 18 and 19 include tungsten (W), aluminum (Al), and copper (Cu). The light-shielding metals 18 and 19 are separated at the boundary between the effective pixel region 12 and the light-shielding pixel region 13 and are not electrically connected. The wiring layer 20 has an interlayer insulating film and wiring (not shown) stacked in multiple layers with the interlayer insulating film interposed therebetween, and drives the pixel transistors (not shown) of each pixel 8 via the multiple layers of wiring.

[0021] In the solid-state imaging device 1 having the above configuration, light is incident from the back surface S1 side of the semiconductor substrate 14, passes through an on-chip lens and a color filter (not shown), and undergoes photoelectric conversion in the photoelectric conversion unit PD to generate electric charges. The generated electric charges are then output as pixel signals from vertical signal lines 10 (see FIG. 1 ) formed by wiring in the wiring layer 20. Furthermore, in the solid-state imaging device 1 according to the first embodiment, the end of the second conductor 25 on the front surface S3 side in the second inter-pixel isolation structure 23 in the light-shielded pixel region 13 is electrically connected to a negative bias voltage supply source. This applies a negative bias voltage to the first conductor 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 via the second conductor 25 and the light-shielding metal 19, creating a high hole concentration in the peripheral portion of the first inter-pixel isolation structure 22 and suppressing the generation of dark current.

[0022] Consider, for example, a case where the first conductor 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 is filled with the same conductive material as the second conductor 25 in the second inter-pixel isolation structure 23 in the light-shielded pixel region 13. That is, suppose doped polysilicon is also used as the material for the first conductor 16. In this case, because polysilicon has the property of absorbing light, incident light is absorbed by the first inter-pixel isolation structure 22 in the effective pixel region 12. This may result in a decrease in the amount of light photoelectrically converted by the photoelectric conversion unit PD in the effective pixel region 12, resulting in a decrease in sensitivity. In contrast, in the solid-state imaging device 1 according to the first embodiment, the first conductor 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 and the second conductor 25 in the second inter-pixel isolation structure 23 in the light-shielded pixel region 13 are configured to be made of different conductive materials. Therefore, by selecting a conductive material for the first conductor 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 that corresponds to the desired pixel characteristics, the characteristics of the pixels 8 can be improved. More specifically, in the first embodiment, the first conductor 16 is formed of a conductive material (ITO) having a lower light absorption rate than the second conductor 25. This can suppress absorption of incident light by the first inter-pixel isolation structure 22 in the effective pixel region 12, thereby suppressing a decrease in sensitivity of the pixels 8. Furthermore, the second conductor 25 is formed of doped polysilicon. Here, doped polysilicon has better embedding properties than ITO. Therefore, during the manufacture of the solid-state imaging device 1, the process of embedding the second conductor 25 in the space within the trench portion 26 of the second inter-pixel isolation structure 23, i.e., the narrow space penetrating the semiconductor substrate 14, can be performed relatively easily.

[0023] [1-3 Manufacturing Method of Solid-State Imaging Device] Next, a method for manufacturing the solid-state imaging device 1 according to the first embodiment will be described. First, as shown in FIG. 5, a semiconductor substrate 14 is prepared on which a second inter-pixel isolation structure 23 and a wiring layer 20 are formed. Doped polysilicon is embedded as a second conductor 25 in the second inter-pixel isolation structure 23. Next, using lithography and dry etching, a trench portion 24 of the first inter-pixel isolation structure 22 is formed on the rear surface S1 of the prepared semiconductor substrate 14. Next, an insulator 27 is formed so as to continuously cover the sidewall surfaces of the formed trench portion 24 and the rear surface S1 of the semiconductor substrate 14. For example, chemical vapor deposition (CVD) or thermal oxidation can be used as a method for forming the insulator 27.

[0024] Next, as shown in FIG. 6 , a first conductor 16 is formed to continuously cover the space between the sidewall surfaces covered with the insulator 15 and the back surface S6 of the insulator 27. ITO, which has a lower light absorption rate than doped polysilicon, is used as the material for the first conductor 16. Next, as shown in FIG. 7 , an insulating film 17 is formed on the back surface S4 of the first conductor 16, and then a resist mask 29 having an opening at a position where the light-shielding metal 19 (see FIG. 3 ) will be formed is formed. Next, as shown in FIG. 8 , etching is performed through the resist mask 29 to remove portions of the first conductor 16 and the insulator 15, thereby exposing the back surface S1 of the semiconductor substrate 14. This exposes the second conductor 25 on the back surface S1. Next, the resist mask 29 is removed, and as shown in FIG. 9 , a film of the material for the light-shielding metal 19 (e.g., tungsten (W)) is formed to a uniform thickness over the entire back surface S1 side of the semiconductor substrate 14. As a result, the surface S7 of the light-shielding metal 19 is electrically connected to the second conductor 25, and the end of the light-shielding metal 19 on the effective pixel region 12 side is electrically connected to the first conductor 16. Then, a contact 28 connected to a supply source of a negative bias voltage is connected to the first conductor 16 via the second conductor 25 and the light-shielding metal 19. Next, the material of the formed light-shielding metal 19 is removed from the back surface S5 of the insulating film 17 in the effective pixel region 12, to form the light-shielding metal 19. Thereafter, the light-shielding metal 18 (see FIG. 3), a color filter, an on-chip lens, etc. are formed on the back surface S5 of the insulating film 17 in the effective pixel region 12. By this procedure, the solid-state imaging device 1 shown in FIG. 3 is manufactured.

[0025] 2. Second Embodiment [2-1 Configuration of Main Parts] Next, a solid-state imaging device 1 according to a second embodiment of the present disclosure will be described. The overall configuration of the solid-state imaging device 1 according to the second embodiment is the same as that shown in FIG. 1 , and is therefore not shown. FIG. 10 is a diagram corresponding to FIG. 2 of the first embodiment, and is a diagram illustrating the planar configuration of one of the four corners of the pixel region 2 of the solid-state imaging device 1 according to the second embodiment. FIG. 11 is a diagram corresponding to FIG. 3 of the first embodiment, and is a diagram illustrating the cross-sectional configuration of the solid-state imaging device 1 taken along line CC in FIG. 10 . FIG. 12 is a diagram corresponding to FIG. 4 of the first embodiment, and is a diagram illustrating the cross-sectional configuration of the solid-state imaging device 1 taken along line DD in FIG. 10 . In FIGS. 10 , 11 , and 12 , parts corresponding to FIGS. 2 , 3 , and 4 are designated by the same reference numerals, and redundant description will be omitted. The solid-state imaging device 1 according to the second embodiment differs from the solid-state imaging device 1 according to the first embodiment in the configurations and materials of the first conductors 16 and second conductors 25 and the configuration of the light-shielding metal 18. Furthermore, the insulating film 17 is omitted in the solid-state imaging device 1 according to the third embodiment.

[0026] As shown in FIGS. 11 and 12 , the first conductor 16 is disposed in the space within the trench portion 24, i.e., in the space between the sidewall surfaces covered with the insulator 15, from the back surface S1 to the bottom surface of the trench portion 24. This electrically integrates the first conductor 16 in each portion within the trench portion 24, and the back surface S1 side of the first conductor 16 is exposed to the back surface S1 of the semiconductor substrate 14. The material (conductive material) of the first conductor 16 can be, for example, doped polysilicon. The second conductor 25 is embedded in the space within the trench portion 26, i.e., in the space between the sidewall surfaces covered with the insulator 27. This electrically integrates the second conductor 25 in each portion within the trench portion 26. The second conductor 25 is disposed so as to penetrate the semiconductor substrate 14 from the back surface S1 to the front surface S3 of the semiconductor substrate 14. By penetrating the semiconductor substrate 14, the second conductor 25 is exposed on both the front surface S3 and the back surface S1 of the semiconductor substrate 14. The second conductor 25 can be made of the same material (conductive material) as the light-shielding metal 19, such as tungsten (W). In other words, in the second embodiment, the first conductor 16 is formed of a conductive material having a higher light absorption rate than the second conductor 25. The light absorption rate of doped polysilicon is greater than that of tungsten (W). The second conductor 25 is electrically connected to a negative bias voltage source on the front surface S3 side via a contact 28, and a negative bias voltage is applied from the front surface S3 side. By applying a negative bias voltage, the peripheral portion of the second inter-pixel isolation structure 23 in the light-shielded pixel region 13 can be made into a high hole concentration state, thereby suppressing the generation of dark current.

[0027] The light-shielding metal 18 is disposed on the back surface S6 side of the insulator 15 in the effective pixel region 12 and is formed to cover the area between the photoelectric conversion units PD on the back surface S6 of the insulator 15 in the effective pixel region 12. The surface of the light-shielding metal 18 facing the insulator 15 (hereinafter also referred to as the "surface S8") has a convex portion 30 penetrating the insulator 15 at a portion facing the first conductor 16, and is in contact with and electrically connected to the first conductor 16 exposed on the back surface S1 of the semiconductor substrate 14 (i.e., the end of the first conductor 16 on the back surface S1 side). The light-shielding metal 19 is disposed on the back surface S1 side of the semiconductor substrate 14 in the light-shielding pixel region 13 and is formed to cover the entire back surface S1 of the semiconductor substrate 14 in the light-shielding pixel region 13. The surface S7 of the light-shielding metal 19 is in contact with and electrically connected to the second conductor 25 exposed on the back surface S1 of the semiconductor substrate 14 (i.e., the end of the second conductor 25 on the back surface S1 side). As a result, the first conductor 16 and the second conductor 25 are electrically connected to each other via the light-shielding metals 18 and 19. Therefore, a negative bias voltage applied to the second conductor 25 from the surface S3 side is applied to the first conductor 16 via the second conductor 25 and the light-shielding metals 18 and 19. That is, a transmission path for the negative bias voltage is formed using the light-shielding metal 18 and the light-shielding metal 19 used to shield the photoelectric conversion unit PD in the light-shielding pixel region 13. Therefore, in the effective pixel region 12, the periphery of the first inter-pixel isolation structure 22 can be made into a high hole concentration state, thereby suppressing the generation of dark current. Examples of materials that can be used for the light-shielding metals 18 and 19 include tungsten (W), aluminum (Al), and copper (Cu). Figure 11 illustrates an example in which the light-shielding metals 18 and 19 and the second conductor 25 are integrally formed using the same material. The light-shielding metal 18 and the light-shielding metal 19 are connected at the boundary between the effective pixel area 12 and the light-shielding pixel area 13 and are formed integrally.

[0028] With the above configuration, in the solid-state imaging device 1 according to the second embodiment, the first conductor 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 and the second conductor 25 in the second inter-pixel isolation structure 23 in the light-shielded pixel region 13 are formed using different conductive materials. Therefore, by selecting a conductive material for the first conductor 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 that corresponds to desired pixel characteristics, the characteristics of the pixels 8 can be improved. More specifically, in the second embodiment, the first conductor 16 is formed using a conductive material (doped polysilicon) that has a higher light absorption rate than the second conductor 25. Therefore, in the effective pixel region 12, the absorption of incident light by the first inter-pixel isolation structure 22 can be improved, and optical color mixing can be more appropriately suppressed. Therefore, it is preferable in a configuration where color mixing is more of a problem than sensitivity, such as when a SPAD (Single Photon Avalanche Diode) in which avalanche multiplication occurs in response to incident photons and current flows is used as the photoelectric conversion unit PD.

[0029] 3. Third Embodiment [3-1 Configuration of Main Parts] Next, a solid-state imaging device 1 according to a third embodiment of the present disclosure will be described. The overall configuration of the solid-state imaging device 1 according to the third embodiment is the same as that shown in FIG. 1 and is therefore not shown. FIG. 13 corresponds to FIG. 3 of the first embodiment and shows a cross-sectional configuration of the solid-state imaging device 1 taken along line A-A in FIG. 2. FIG. 14 corresponds to FIG. 4 of the first embodiment and shows a cross-sectional configuration of the solid-state imaging device 1 taken along line B-B in FIG. 2. In FIGS. 13 and 14, parts corresponding to FIGS. 3 and 4 are designated by the same reference numerals, and redundant description will be omitted. The solid-state imaging device 1 according to the third embodiment differs from the solid-state imaging device 1 according to the first embodiment in the configuration of the insulator 15 and the materials and configurations of the first conductor 16 and the second conductor 25.

[0030] The insulator 15 continuously covers the sidewall surfaces of the trench portion 24 in the effective pixel region 12 and the entire back surface S1 of the semiconductor substrate 14 (both the effective pixel region 12 and the light-shielded pixel region 13). As shown in FIGS. 13 and 14 , the first conductor 16 is disposed in the space within the trench portion 24, i.e., in the space between the sidewall surfaces covered with the insulator 15, from the back surface S1 to the bottom surface of the trench portion 24. This electrically integrates each portion of the first conductor 16 within the trench portion 24. In addition to the space within the trench portion 24, the first conductor 16 also continuously covers a region (grid-shaped region) along the back surface S6 of the insulator 15 between the photoelectric conversion units PD in the effective pixel region 12 and the entire back surface S6 of the insulator 15 in the light-shielded pixel region 13. That is, they are continuously disposed in the first inter-pixel isolation structure 22, in regions along the spaces between the photoelectric conversion units PD on the back surface S1 of the semiconductor substrate 14 in the effective pixel region 12, and over the entire back surface S1 of the semiconductor substrate 14 in the light-shielded pixel region 13. In addition, in the light-shielded pixel region 13, the surface of the first conductor 16 facing the insulator 15 (hereinafter also referred to as the "surface S9") has a convex portion 31 that penetrates the insulator 15 in a portion facing the second conductor 25, and is in contact with the back surface S1 of the semiconductor substrate 14. In addition, ITO, for example, can be used as the material (conductive material) of the first conductor 16.

[0031] The second conductor 25 is embedded in the space within the trench portion 26, i.e., the space between the sidewall surfaces covered with the insulator 27. This electrically integrates each portion of the second conductor 25 within the trench portion 26. The second conductor 25 is disposed so as to penetrate the semiconductor substrate 14 from the back surface S1 to the front surface S3 of the semiconductor substrate 14. By penetrating the semiconductor substrate 14, the second conductor 25 is exposed on both the front surface S3 and the back surface S1 of the semiconductor substrate 14. The end of the second conductor 25 exposed from the front surface S3 side is electrically connected to a negative bias voltage supply source via a contact 28, and a negative bias voltage is applied from the front surface S3 side. By applying the negative bias voltage, the peripheral portion of the second inter-pixel isolation structure 23 in the light-shielded pixel region 13 can be made to have a high hole concentration, thereby suppressing the generation of dark current.

[0032] Furthermore, the end of the second conductor 25 exposed from the back surface S1 side is in contact with and electrically connected to the first conductor 16 located on the back surface S1 side of the semiconductor substrate 14 in the light-shielding pixel region 13. As a result, the first conductor 16 and the second conductor 25 are electrically connected to each other without the light-shielding metals 18, 19 interposed therebetween. Therefore, a negative bias voltage applied to the second conductor 25 from the front surface S3 side is applied to the first conductor 16 in the first inter-pixel isolation structure 22 via the second conductor 25 and the first conductor 16 located on the back surface S1 side. That is, a transmission path for the negative bias voltage to the first conductor 16 in the first inter-pixel isolation structure 22 is formed using the first conductor 16 located on the back surface S1 side. Therefore, in the effective pixel region 12, the peripheral portion of the first inter-pixel isolation structure 22 can be made to have a high hole concentration, thereby suppressing the generation of dark current. Furthermore, tungsten (W), for example, can be used as the material (conductive material) of the second conductor 25. That is, in the third embodiment, the first conductor 16 is formed of a conductive material having a lower light absorption rate than the second conductor 25. The relationship between the light absorption rate of ITO and the light absorption rate of tungsten (W) is such that the light absorption rate of ITO is lower than the light absorption rate of tungsten.

[0033] As described above, in the solid-state imaging device 1 according to the third embodiment, the first conductors 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 and the second conductors 25 in the second inter-pixel isolation structure 23 in the light-shielded pixel region 13 are formed using different conductive materials. Therefore, by selecting a conductive material for the first conductors 16 in the first inter-pixel isolation structure 22 in the effective pixel region 12 that corresponds to desired pixel characteristics, the characteristics of the pixels 8 can be improved. More specifically, in the third embodiment, the first conductors 16 are formed using a conductive material (ITO) that has a lower light absorption rate than the second conductors 25. Therefore, absorption of incident light by the first inter-pixel isolation structure 22 in the effective pixel region 12 can be suppressed, thereby improving sensitivity. Furthermore, the first conductors 16 located on the back surface S1 side of the semiconductor substrate 14 in the light-shielded pixel region 13 are used as a transmission path for a negative bias voltage. Therefore, for example, compared to using a light-shielding metal 19 as a transmission path, there is no need to prepare a material for forming the transmission path separately from the material for the first conductor 16, and the increase in the number of processes involved in forming the transmission path can be suppressed.

[0034] [3-2 Modifications] (1) Although the first, second, and third embodiments each show an example in which a transmission path for a negative bias voltage is formed on the back surface S1 side of the semiconductor substrate 14, other configurations may be employed. For example, a configuration may be adopted in which a location at the boundary between the trench portion 24 of the first inter-pixel isolation structure 22 and the trench portion 26 of the second inter-pixel isolation structure 23, where the first conductor 16 and the second conductor 25 in the trench portions 24 and 26 are in direct contact, is used as the transmission path for the negative bias voltage. (2) Furthermore, the first, second, and third embodiments each show an example in which a negative bias voltage is applied from the front surface S3 side of the second conductor 25, but other configurations may be employed. For example, a configuration may be adopted in which a negative bias voltage is applied from the back surface S1 side of the second conductor 25.

[0035] (3) Furthermore, the present technology can be applied to photodetection devices in general, including distance measurement sensors that measure distance, also known as time-of-flight (ToF) sensors, in addition to the solid-state imaging device 1 as the image sensor described above. A distance measurement sensor emits light toward an object, detects the light reflected from the surface of the object, and calculates the distance to the object based on the time of flight between when the light is emitted and when the reflected light is received. The light-receiving pixel structure of this distance measurement sensor can employ the structure of pixel 8 described above.

[0036] 4. Fourth Embodiment The technology according to the present disclosure (the present technology) can be applied to various electronic devices. Fig. 15 is a diagram showing an example of a schematic configuration of an imaging device (such as a video camera or a digital still camera) as an electronic device to which the present technology is applied. As shown in Fig. 15, the imaging device 1000 includes a lens group 1001, a solid-state imaging device 1002 (the solid-state imaging device 1 according to the first embodiment), a DSP (Digital Signal Processor) circuit 1003, a frame memory 1004, a monitor 1005, and a memory 1006. The DSP circuit 1003, the frame memory 1004, the monitor 1005, and the memory 1006 are connected to each other via a bus line 1007.

[0037] The lens group 1001 guides incident light (image light) from a subject to the solid-state imaging device 1002, forming an image on the light-receiving surface (pixel region) of the solid-state imaging device 1002. The solid-state imaging device 1002 is composed of the CMOS image sensor of the first embodiment described above. The solid-state imaging device 1002 converts the amount of incident light imaged on the light-receiving surface by the lens group 1001 into an electrical signal on a pixel-by-pixel basis and supplies the pixel signal to the DSP circuit 1003. The DSP circuit 1003 performs predetermined image processing on the pixel signal supplied from the solid-state imaging device 1002. The DSP circuit 1003 then supplies the processed image signal on a frame-by-frame basis to the frame memory 1004, where it is temporarily stored. The monitor 1005 is composed of a panel display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel. The monitor 1005 displays an image (moving image) of the subject based on the pixel signals in frame units temporarily stored in the frame memory 1004. The memory 1006 is made up of a DVD, a flash memory, etc. The memory 1006 reads out and records the pixel signals in frame units temporarily stored in the frame memory 1004.

[0038] Note that the electronic device to which the solid-state imaging device 1 can be applied is not limited to the imaging device 1000, and can also be applied to other electronic devices. Also, although the solid-state imaging device 1 according to the first embodiment is used as the solid-state imaging device 1002, other configurations can also be adopted. For example, the solid-state imaging device 1 according to the second embodiment or the third embodiment, the solid-state imaging device 1 according to a modification, or another photodetector device to which the present technology is applied may be used.

[0039] 5. Fifth Embodiment The technology according to the present disclosure (the present technology) can be applied to a medical imaging system. The medical imaging system is a medical system that uses imaging technology, such as an endoscope system or a microscope system.

[0040] [Endoscopic System] An example of an endoscope system will be described with reference to FIGS. 16 and 17 . FIG. 16 is a diagram illustrating an example of the schematic configuration of an endoscope system 5000 to which the technology according to the present disclosure can be applied. FIG. 17 is a diagram illustrating an example of the configuration of an endoscope 5001 and a CCU (Camera Control Unit) 5039. FIG. 16 illustrates a state in which an operator (e.g., a doctor) 5067, who is a surgical participant, is performing surgery on a patient 5071 on a patient bed 5069 using the endoscope system 5000. As shown in FIG. 16 , the endoscope system 5000 includes an endoscope 5001, which is a medical imaging device, a CCU 5039, a light source device 5043, a recording device 5053, an output device 5055, and a support device 5027 that supports the endoscope 5001.

[0041] In endoscopic surgery, an insertion aid called a trocar 5025 is inserted into a patient 5071. Then, a scope 5003 and surgical tools 5021 connected to an endoscope 5001 are inserted into the body of the patient 5071 via the trocar 5025. The surgical tools 5021 are, for example, energy devices such as an electric scalpel, forceps, etc.

[0042] A surgical image, which is a medical image showing the inside of the body of a patient 5071 photographed by an endoscope 5001, is displayed on a display device 5041. An operator 5067 performs a procedure on the surgical target using a surgical tool 5021 while viewing the surgical image displayed on the display device 5041. Note that the medical image is not limited to a surgical image, and may be a diagnostic image photographed during a diagnosis.

[0043] [Endoscope] The endoscope 5001 is an imaging unit that captures images of the inside of the patient's body 5071. For example, as shown in FIG. 17 , the endoscope 5001 is a camera 5005 that includes a focusing optical system 50051 that focuses incident light, a zoom optical system 50052 that changes the focal length of the imaging unit to enable optical zoom, a focus optical system 50053 that changes the focal length of the imaging unit to enable focus adjustment, and a light-receiving element 50054. The endoscope 5001 generates pixel signals by focusing light onto the light-receiving element 50054 via a connected scope 5003, and outputs the pixel signals to the CCU 5039 via a transmission system. The scope 5003 has an objective lens at its tip and is an insertion section that guides light from a connected light source device 5043 into the inside of the patient's body 5071. The scope 5003 is, for example, a rigid scope if it is a rigid endoscope or a flexible scope if it is a flexible endoscope. The scope 5003 may be a direct-view endoscope or an oblique-view endoscope. Furthermore, the pixel signal may be a signal based on a signal output from a pixel, such as a RAW signal or an image signal. Furthermore, a configuration may be adopted in which a memory is installed in the transmission system connecting the endoscope 5001 and the CCU 5039, and parameters related to the endoscope 5001 and the CCU 5039 are stored in the memory. The memory may be located, for example, in a connection portion of the transmission system or on a cable. For example, parameters at the time of shipment of the endoscope 5001 and parameters that change when power is applied may be stored in the memory of the transmission system, and the operation of the endoscope may be changed based on parameters read from the memory. Furthermore, the endoscope and the transmission system may be collectively referred to as an endoscope. The light-receiving element 50054 is a sensor that converts received light into a pixel signal, and is, for example, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. It is preferable that the light-receiving element 50054 be an image sensor capable of color imaging with a Bayer array. Furthermore, the light receiving element 50054 is preferably an imaging element having a number of pixels corresponding to a resolution of, for example, 4K (3840 horizontal pixels × 2160 vertical pixels), 8K (7680 horizontal pixels × 4320 vertical pixels), or square 4K (3840 or more horizontal pixels × 3840 or more vertical pixels). The light receiving element 50054 may be a single sensor chip or multiple sensor chips.For example, a prism may be provided to separate incident light into predetermined wavelength bands, and each wavelength band may be imaged by a different light-receiving element. Alternatively, multiple light-receiving elements may be provided for stereoscopic vision. The light-receiving element 50054 may be a sensor including an image processing circuit within its chip structure, or a Time of Flight (ToF) sensor. The transmission system may be, for example, an optical fiber cable or wireless transmission. Wireless transmission may be performed via any means capable of transmitting pixel signals generated by the endoscope 5001. For example, the endoscope 5001 and the CCU 5039 may be connected wirelessly, or the endoscope 5001 and the CCU 5039 may be connected via a base station in the operating room. In this case, the endoscope 5001 may simultaneously transmit not only pixel signals but also information related to the pixel signals (e.g., pixel signal processing priority, synchronization signal, etc.). The endoscope may be configured such that the scope and camera are integrated, or a light-receiving element is provided at the tip of the scope.

[0044] [CCU (Camera Control Unit)] The CCU 5039 is a control device that comprehensively controls the connected endoscope 5001 and light source device 5043. For example, as shown in FIG. 17 , the CCU 5039 is an information processing device having an FPGA 50391, a CPU 50392, a RAM 50393, a ROM 50394, a GPU 50395, and an I / F 50396. The CCU 5039 may also comprehensively control the connected display device 5041, recording device 5053, and output device 5055. For example, the CCU 5039 controls the irradiation timing, irradiation intensity, and type of irradiation light source of the light source device 5043. The CCU 5039 also performs image processing such as development processing (e.g., demosaic processing) and correction processing on pixel signals output from the endoscope 5001, and outputs the processed pixel signals (e.g., an image) to an external device such as the display device 5041. Furthermore, the CCU 5039 transmits a control signal to the endoscope 5001 to control the driving of the endoscope 5001. The control signal is, for example, information regarding imaging conditions such as the magnification and focal length of the imaging unit. The CCU 5039 may have an image down-conversion function and be configured to be able to simultaneously output a high-resolution (e.g., 4K) image to the display device 5041 and a low-resolution (e.g., HD) image to the recording device 5053.

[0045] The CCU 5039 may also be connected to external devices (e.g., recording devices, display devices, output devices, and support devices) via an IP converter that converts signals into a predetermined communication protocol (e.g., IP (Internet Protocol)). The connection between the IP converter and the external devices may be configured as a wired network, or a partial or entire network may be configured as a wireless network. For example, the IP converter on the CCU 5039 side may have a wireless communication function and transmit the received video to an IP switcher or an output-side IP converter via a wireless communication network such as a fifth-generation mobile communication system (5G) or a sixth-generation mobile communication system (6G).

[0046] [Light Source Device] The light source device 5043 is a device capable of emitting light in a predetermined wavelength band and includes, for example, multiple light sources and a light source optical system that guides the light from the multiple light sources. The light sources are, for example, a xenon lamp, an LED light source, or an LD light source. The light source device 5043 has, for example, LED light sources corresponding to the three primary colors R, G, and B, and emits white light by controlling the output intensity and output timing of each light source. Furthermore, the light source device 5043 may include a light source that can emit special light used for special light observation, in addition to a light source that emits normal light used for normal light observation. The special light is light in a predetermined wavelength band different from the normal light used for normal light observation, such as near-infrared light (light with a wavelength of 760 nm or more), infrared light, blue light, or ultraviolet light. The normal light is, for example, white light or green light. Narrowband light observation, a type of special light observation, alternately emits blue light and green light to utilize the wavelength-dependence of light absorption in body tissue, enabling high-contrast imaging of specific tissue, such as blood vessels on the surface of the mucous membrane. Furthermore, in fluorescence observation, a type of special light observation, excitation light is applied to excite a drug injected into the body tissue, and fluorescence emitted by the drug as a marker is received to obtain a fluorescence image, thereby making it easier for the surgeon to visualize body tissues that are difficult for the surgeon to see under normal light. For example, in fluorescence observation using infrared light, infrared light having an excitation wavelength band is applied to a drug such as indocyanine green (ICG) injected into the body tissue, and the fluorescence of the drug is received, making it easier to visualize the structure of the body tissue and affected areas. Furthermore, in fluorescence observation, a drug (e.g., 5-ALA) that is excited by special light in the blue wavelength band and emits fluorescence in the red wavelength band may be used. The type of light irradiated by the light source device 5043 is set under the control of the CCU 5039. The CCU 5039 may have a mode in which normal light observation and special light observation are alternately performed by controlling the light source device 5043 and the endoscope 5001. In this case, it is preferable to superimpose information based on pixel signals obtained by special light observation on pixel signals obtained by normal light observation. The special light observation may be infrared light observation, which irradiates infrared light to view areas deeper than the surface of an organ, or multispectral observation using hyperspectral spectroscopy. Furthermore, photodynamic therapy may be combined.

[0047] [Recording Device] The recording device 5053 is a device, such as a recorder, that records pixel signals (e.g., images) acquired from the CCU 5039. The recording device 5053 records images acquired from the CCU 5039 on a HDD, SSD, or optical disk. The recording device 5053 may be connected to a network within the hospital so as to be accessible from devices outside the operating room. The recording device 5053 may also have an image down-conversion or up-conversion function.

[0048] [Display Device] The display device 5041 is a device capable of displaying an image, such as a display monitor. The display device 5041 displays an image based on pixel signals acquired from the CCU 5039. The display device 5041 may also function as an input device that enables gaze recognition, voice recognition, and instruction input using gestures by including a camera and a microphone.

[0049] [Output Device] The output device 5055 is a device, such as a printer, that outputs information acquired from the CCU 5039. The output device 5055 prints, for example, a print image based on pixel signals acquired from the CCU 5039 onto paper.

[0050] [Support Device] The support device 5027 is an articulated arm including a base 5029 having an arm control device 5045, an arm 5031 extending from the base 5029, and a holder 5032 attached to the tip of the arm 5031. The arm control device 5045 is configured with a processor such as a CPU and controls the drive of the arm 5031 by operating according to a predetermined program. The support device 5027 controls the position and posture of the endoscope 5001 held by the holder 5032, for example, by controlling parameters such as the length of each link 5035 constituting the arm 5031 and the rotation angle and torque of each joint 5033 using the arm control device 5045. This allows the endoscope 5001 to be changed to a desired position or posture, allowing the scope 5003 to be inserted into the patient 5071 and the observation area within the body to be changed. The support device 5027 functions as an endoscope support arm that supports the endoscope 5001 during surgery. This allows the support device 5027 to take the place of an assistant scopist who holds the endoscope 5001. The support device 5027 may also be a device that supports a microscope device 5301 (described later) and may also be called a medical support arm. The support device 5027 may be controlled autonomously by the arm control device 5045, or may be controlled by the arm control device 5045 based on user input. For example, the control method may be a master-slave method in which the support device 5027, which serves as a slave device (replica device) serving as a patient cart, is controlled based on the movement of a master device (primary device) that serves as an operator console near the user. The support device 5027 may also be remotely controlled from outside the operating room.

[0051] The above describes an example of an endoscope system 5000 to which the technology according to the present disclosure can be applied. For example, the technology according to the present disclosure may be applied to a microscope system.

[0052] 18 is a diagram showing an example of the schematic configuration of a microsurgical system to which the technology according to the present disclosure can be applied. In the following description, components similar to those in the endoscope system 5000 are designated by the same reference numerals, and redundant description thereof will be omitted.

[0053] 18 is a schematic illustration of an operator 5067 performing surgery on a patient 5071 on a patient bed 5069 using a microsurgical system 5300. For simplicity, the illustration of the cart 5037 of the microsurgical system 5300 is omitted, and a microscope device 5301 that replaces the endoscope 5001 is simplified. However, the microscope device 5301 in this description may refer to the microscope unit 5303 provided at the tip of the link 5035, or may refer to the entire configuration including the microscope unit 5303 and the support device 5027.

[0054] 18 , during surgery, a microsurgical system 5300 is used to capture an image of the surgical site captured by a microscope device 5301 and display it enlarged on a display device 5041 installed in an operating room. The display device 5041 is installed in a position facing the surgeon 5067, who performs various procedures on the surgical site, such as resecting the affected area, while observing the state of the surgical site using the image displayed on the display device 5041. Microsurgical systems are used, for example, in ophthalmic surgery and brain surgery.

[0055] The above describes examples of an endoscopic system 5000 and a microsurgery system 5300 to which the technology of the present disclosure can be applied. Note that the systems to which the technology of the present disclosure can be applied are not limited to these examples. For example, the support device 5027 may support another observation device or another surgical tool at its tip instead of the endoscope 5001 or the microscope unit 5303. Examples of such other observation devices include forceps, a surgeon, an insufflation tube for insufflation, or an energy treatment tool for incising tissue or sealing blood vessels by cauterization. Supporting these observation devices and surgical tools with a support device allows them to be more stably fixed in position than when medical staff support them manually, and also reduces the burden on medical staff. The technology of the present disclosure may be applied to support devices that support components other than the microscope unit.

[0056] The technology disclosed herein can be suitably applied to the light-receiving element among the above-described configurations. By applying the technology disclosed herein to the light-receiving element, clearer images of the surgical site can be obtained, making it possible to perform surgery safely and more reliably.

[0057] The present technology may also be configured as follows: (1) A photodetector device including: a semiconductor substrate; a plurality of photoelectric conversion units formed in a two-dimensional array on the semiconductor substrate; and an inter-pixel isolation structure formed in a region between the photoelectric conversion units on the semiconductor substrate, wherein the inter-pixel isolation structure has a first inter-pixel isolation structure that is a portion within an effective pixel region and a second inter-pixel isolation structure that is a portion within a light-shielded pixel region that surrounds the periphery of the effective pixel region, wherein a first conductor is arranged within the first inter-pixel isolation structure, and a second conductor that is electrically connected to the first conductor and to which a negative bias voltage is applied is arranged within the second inter-pixel isolation structure, and the first conductor and the second conductor are formed using mutually different conductive materials. (2) The photodetector according to (1), further comprising a light-shielding metal disposed on the first surface side, which is a light-receiving surface of the semiconductor substrate, and covering the first surface of the semiconductor substrate in the light-shielding pixel region, wherein the first conductor and the second conductor are electrically connected to each other via the light-shielding metal, and the negative bias voltage is applied to the second conductor from the second surface side. (3) The photodetector according to (2), wherein the first conductor is formed of a conductive material having a lower light absorption rate than the second conductor. (4) The photodetector according to (3), wherein the material of the first conductor is ITO, and the material of the second conductor is doped polysilicon. (5) The photodetector according to (3) or (4), wherein the first inter-pixel isolation structure and the first conductor are formed from the first surface to a portion of the space between the first surface and a second surface, which is the surface opposite the first surface, and the second inter-pixel isolation structure and the second conductor are formed so as to penetrate the semiconductor substrate from the first surface to the second surface.(6) The photodetector according to (5), wherein the first conductor is continuously disposed in the first inter-pixel isolation structure and in a region along between the photoelectric conversion units on the first surface of the semiconductor substrate in the effective pixel region, and an end of the first conductor on the light-shielding pixel region side of the portion located on the first surface is in contact with and electrically connected to an end of the light-shielding metal on the effective pixel region side, and the end of the second conductor on the first surface side is in contact with and electrically connected to an opposing surface of the light-shielding metal that faces the first surface. (7) The photodetector according to (2), wherein the first conductor is formed of a conductive material having a higher light absorption rate than the second conductor. (8) The photodetector according to (7), wherein the material of the first conductor is doped polysilicon, and the material of the second conductor is tungsten. (9) The photodetector according to (7) or (8), wherein the first inter-pixel isolation structure and the first conductor are formed from the first surface to partway between the first surface and a second surface that is the surface opposite to the first surface, and the second inter-pixel isolation structure and the second conductor are formed so as to penetrate the semiconductor substrate from the first surface to the second surface. (10) The photodetector according to (9), wherein the light-shielding metal covers the entire first surface of the semiconductor substrate in the light-shielding pixel region and a region of the first surface of the semiconductor substrate that is in the effective pixel region and extends between the photoelectric conversion units, and wherein ends of the first conductor and the second conductor on the first surface side are in contact with and electrically connected to an opposing surface of the light-shielding metal that faces the first surface.(11) The photodetector according to (1), wherein the first inter-pixel isolation structure and the first conductor are formed from a first surface that is a light-receiving surface of the semiconductor substrate to a portion of the way between the first surface and a second surface that is a surface opposite to the first surface, the second inter-pixel isolation structure and the second conductor are formed to penetrate the semiconductor substrate from the first surface to the second surface, the first conductor is continuously disposed within the first inter-pixel isolation structure, in a region along between the photoelectric conversion units on the first surface that is the light-receiving surface of the semiconductor substrate in the effective pixel region, and over the entire first surface of the semiconductor substrate in the light-shielded pixel region, an end of the second conductor on the first surface side is in contact with and electrically connected to an opposing surface of the first conductor that faces the first surface, and the negative bias voltage is applied to the second conductor from the second surface side. (12) The photodetector according to (11), wherein the first conductor is formed of a conductive material having a lower light absorption rate than the second conductor. (13) The photodetector according to (12), wherein a material of the first conductor is ITO, and a material of the second conductor is tungsten. (14) An electronic device comprising: a photodetector having a semiconductor substrate, a plurality of photoelectric conversion units formed in a two-dimensional array on the semiconductor substrate, and an inter-pixel isolation structure formed in a region between the photoelectric conversion units on the semiconductor substrate, the inter-pixel isolation structure having a first inter-pixel isolation structure that is a portion within an effective pixel region and a second inter-pixel isolation structure that is a portion within a light-shielded pixel region that surrounds the periphery of the effective pixel region, a first conductor disposed in the first inter-pixel isolation structure, and a second conductor electrically connected to the first conductor and to which a negative bias voltage is applied disposed in the second inter-pixel isolation structure, the first conductor and the second conductor being formed using mutually different conductive materials.

[0058] REFERENCE SIGNS LIST 1...solid-state imaging device, 2...pixel region, 3...vertical drive circuit, 4...column signal processing circuit, 5...horizontal drive circuit, 6...output circuit, 7...control circuit, 8...pixel, 9...pixel drive wiring, 10...vertical signal line, 11...horizontal signal line, 12...effective pixel region, 13...light-shielded pixel region, 14...semiconductor substrate, 15...insulator, 16...first conductor, 17...insulating film, 18, 19...light-shielding metal, 20...wiring layer, 21...inter-pixel isolation structure, 22...first inter-pixel isolation structure, 23...second inter-pixel isolation structure, 24...trench portion, 25...second conductor, 26...trench portion, 27...insulator, 28...contact, 29...resist mask, 30, 31...protruding portion

Claims

1. A photodetector comprising: a semiconductor substrate; a plurality of photoelectric conversion units formed in a two-dimensional array on the semiconductor substrate; and an inter-pixel isolation structure formed in a region between the photoelectric conversion units of the semiconductor substrate, the inter-pixel isolation structure having a first inter-pixel isolation structure which is a portion within an effective pixel region, and a second inter-pixel isolation structure which is a portion within a light-shielded pixel region surrounding the effective pixel region, a first conductor being disposed within the first inter-pixel isolation structure, and a second conductor being electrically connected to the first conductor and having a negative bias voltage applied thereto being disposed within the second inter-pixel isolation structure, the first conductor and the second conductor being formed using mutually different conductive materials.

2. The photodetector according to claim 1, further comprising a light-shielding metal disposed on a first surface side, which is the light-receiving surface of the semiconductor substrate, and covering the first surface of the semiconductor substrate within the light-shielding pixel region, the first conductor and the second conductor being electrically connected to each other via the light-shielding metal.

3. The photodetector according to claim 2, wherein the first conductor is formed of a conductive material having a lower light absorption rate than the second conductor.

4. The photodetector device according to claim 3, wherein the material of the first conductor is ITO, and the material of the second conductor is doped polysilicon.

5. The photodetector device described in claim 3, wherein the first inter-pixel isolation structure and the first conductor are formed from the first surface to partway between the first surface and a second surface which is the surface opposite the first surface, and the second inter-pixel isolation structure and the second conductor are formed so as to penetrate the semiconductor substrate from the first surface to the second surface.

6. The photodetector according to claim 5, wherein the first conductor is continuously disposed within the first inter-pixel isolation structure and in a region along between the photoelectric conversion units on the first surface of the semiconductor substrate in the effective pixel area, and an end portion of the first surface facing the light-shielding pixel area is in contact with and electrically connected to an end portion of the light-shielding metal facing the effective pixel area, the end portion of the second conductor on the first surface side is in contact with and electrically connected to an opposing surface of the light-shielding metal facing the first surface, and the negative bias voltage is applied to the second conductor from the second surface side.

7. The light detection device according to claim 2, wherein the first conductor is formed of a conductive material having a higher light absorption rate than the second conductor.

8. The photodetection device according to claim 7, wherein the material of the first conductor is doped polysilicon, and the material of the second conductor is tungsten.

9. The photodetection device described in claim 7, wherein the first inter-pixel isolation structure and the first conductor are formed from the first surface to partway between the first surface and a second surface which is the surface opposite the first surface, and the second inter-pixel isolation structure and the second conductor are formed so as to penetrate the semiconductor substrate from the first surface to the second surface.

10. The photodetector device of claim 9, wherein the light-shielding metal covers the entire first surface of the semiconductor substrate in the light-shielding pixel region and a region of the first surface of the semiconductor substrate in the effective pixel region along between the photoelectric conversion units, the first conductor and the second conductor have ends on the first surface side in contact with an opposing surface of the light-shielding metal that faces the first surface and are electrically connected, and the negative bias voltage is applied to the second conductor from the second surface side.

11. The photodetector device of claim 1, wherein the first inter-pixel isolation structure and the first conductor are formed from a first surface, which is the light-receiving surface of the semiconductor substrate, to partway between the first surface and a second surface, which is the surface opposite to the first surface; the second inter-pixel isolation structure and the second conductor are formed so as to penetrate the semiconductor substrate from the first surface to the second surface; the first conductor is continuously disposed within the first inter-pixel isolation structure, in a region along between the photoelectric conversion units on the first surface, which is the light-receiving surface of the semiconductor substrate in the effective pixel region, and over the entire first surface of the semiconductor substrate in the light-shielded pixel region; the end of the second conductor on the first surface side is in contact with and electrically connected to an opposing surface of the first conductor that faces the first surface; and the negative bias voltage is applied to the second conductor from the second surface side.

12. The light detection device according to claim 11, wherein the first conductor is formed of a conductive material having a lower light absorption rate than the second conductor.

13. The photodetector device according to claim 12, wherein the material of the first conductor is ITO, and the material of the second conductor is tungsten.

14. Electronic equipment comprising a photodetector device having a semiconductor substrate, a plurality of photoelectric conversion units formed in a two-dimensional array on the semiconductor substrate, and an inter-pixel isolation structure formed in a region between the photoelectric conversion units of the semiconductor substrate, the inter-pixel isolation structure having a first inter-pixel isolation structure which is a portion within an effective pixel region, and a second inter-pixel isolation structure which is a portion within a light-shielding pixel region surrounding the effective pixel region, a first conductor being disposed within the first inter-pixel isolation structure, a second conductor being electrically connected to the first conductor and having a negative bias voltage applied thereto being disposed within the second inter-pixel isolation structure, and the first conductor and the second conductor being formed using mutually different conductive materials.

Images