Optical detection device and electronic apparatus

Abstract

Provided is an optical detection device capable of suppressing a reduction in sensitivity due to thinning of a semiconductor substrate. Specifically, the present invention is configured to comprise: a semiconductor substrate on which a plurality of pixels each having a photoelectric conversion unit are disposed; and a wiring layer that is laminated on the surface of the semiconductor substrate opposite to a light-receiving surface. The wiring layer is disposed so as to overlap at least some photoelectric conversion units among the plurality of photoelectric conversion units in a lamination direction in which the semiconductor substrate and the wiring layer are laminated, and has a reflective layer for reflecting the light passing through the semiconductor substrate to the semiconductor substrate side. The reflective layer is configured to form a reflective metasurface including a plurality of microstructures.

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 and a plurality of photoelectric conversion units that are formed in a two-dimensional array on the semiconductor substrate and receive light in a predetermined wavelength range and perform photoelectric conversion (see, for example, Patent Document 1). The photodetector described in Patent Document 1 generates pixel signals at levels corresponding to the amount of light received, and constructs an image of a subject from the generated pixel signals.

[0003] Japanese Patent Application Laid-Open No. 2021-168316

[0004] In such photodetector devices, reducing the thickness of the semiconductor substrate has been considered in terms of pixel characteristics such as dark current. However, if the semiconductor substrate is made thinner, the incident light may not be fully absorbed by the photoelectric conversion unit, and the unabsorbed light may pass through the photoelectric conversion unit, resulting in a decrease in sensitivity. The decrease in sensitivity is particularly significant in pixels (e.g., red pixels and IR pixels) that detect light in the long wavelength range, which has a low absorption rate in the photoelectric conversion unit (silicon).

[0005] An object of the present disclosure is to provide a photodetector and electronic equipment that can suppress a decrease in sensitivity that accompanies a reduction in the thickness of a semiconductor substrate.

[0006] A photodetector according to one aspect of the present technology comprises: (a) a semiconductor substrate on which a plurality of pixels each having a photoelectric conversion unit are arranged; and (b) a wiring layer stacked on the surface of the semiconductor substrate opposite the light-receiving surface; (c) the wiring layer is arranged so as to overlap at least some of the plurality of photoelectric conversion units in the stacking direction in which the semiconductor substrate and the wiring layer are stacked, and has a reflective layer that reflects light that has passed through the semiconductor substrate toward the semiconductor substrate; and (d) the reflective layer forms a reflective metasurface including a plurality of microstructures.

[0007] An electronic device according to one aspect of the present technology comprises: (a) a semiconductor substrate on which a plurality of pixels each having a photoelectric conversion unit are arranged; (b) a wiring layer stacked on the surface of the semiconductor substrate opposite the light-receiving surface; (c) the wiring layer is arranged so as to overlap at least some of the photoelectric conversion units in the stacking direction in which the semiconductor substrate and the wiring layer are stacked, and has a reflective layer that reflects light that has passed through the semiconductor substrate toward the semiconductor substrate; and (d) the reflective layer comprises a photodetector device that forms a reflective metasurface including a plurality of microstructures.

[0008] 1 is a diagram showing the overall configuration of a solid-state imaging device according to a first embodiment. FIG. 1 is a diagram showing a cross-sectional configuration of a solid-state imaging device when the semiconductor substrate of FIG. 1 is cut along the row direction. FIG. 2 is a diagram showing a cross-sectional configuration of a reflective layer when cut along line A-A in FIG. 2. FIG. 3 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 4 is a diagram showing a cross-sectional configuration of a reflective layer when cut along line B-B in FIG. 4. FIG. 5 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 6 is a diagram showing a cross-sectional configuration of a reflective layer when cut along line C-C in FIG. 6. FIG. 8 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 9 is a diagram showing a cross-sectional configuration of a reflective layer when cut along line D-D in FIG. 10. FIG. 11 is a diagram showing a cross-sectional configuration of a SPAD pixel that detects light in the near-infrared region. FIG. 12 is a diagram showing a cross-sectional configuration of a color filter layer of an RGB+IR image sensor. FIG. 13 is a diagram showing a cross-sectional configuration of a reflective layer of an RGB+IR image sensor. FIG. 14 is a diagram showing a cross-sectional configuration of an RGB-IR stacked image sensor. FIG. 15 is a diagram showing the shape of a microstructure (rectangular prism). FIG. 16 is a diagram showing the shape of a microstructure (cross prism). 27 is a diagram showing the shape of a microstructure (hollow cylindrical shape). FIG. 28 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 29 is a diagram showing a cross-sectional configuration of a reflective layer when cut along line E-E in FIG. 18. FIG. 29 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a second embodiment. FIG. 21 is a diagram showing a cross-sectional configuration of a light-shielding wall when cut along line F-F in FIG. 20. FIG. 21 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 22 is a diagram showing a cross-sectional configuration of a light-shielding wall when cut along line G-G in FIG. 22. FIG. 22 is a diagram showing a cross-sectional configuration of a light-shielding wall of a modified example. FIG. 23 is a diagram showing a cross-sectional configuration of a light-shielding wall of a modified example. FIG. 24 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 27 is a diagram showing a cross-sectional configuration of a light-shielding wall when cut along line I-I in FIG. 29. FIG. 24 is a diagram showing a cross-sectional configuration of a light-shielding wall of a modified example. FIG. 25 is a diagram showing a cross-sectional configuration of a light-shielding wall of a modified example. 34 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 35 is a diagram showing a cross-sectional configuration of a light-shielding wall when cut along line J-J in FIG. 34. FIG. 36 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example.FIG. 36 is a diagram showing a cross-sectional configuration of a light-shielding wall when cut along line K-K in FIG. 36. FIG. 41 is a diagram showing a cross-sectional configuration of a light-shielding wall of a modified example. FIG. 42 is a diagram showing a cross-sectional configuration of a light-shielding wall of a modified example. FIG. 43 is a diagram showing a cross-sectional configuration of a solid-state imaging device according to a modified example. FIG. 44 is a diagram showing a cross-sectional configuration of a light-shielding wall when cut along line J-J in FIG. 41. FIG. 45 is a diagram showing the relationship between positions in a pixel region and the light-shielding wall. FIG. 46 is a diagram showing a schematic configuration of an electronic device according to a third embodiment.

[0009] Examples of photodetection devices and electronic devices according to embodiments of the present disclosure will be described below with reference to FIGS. 1 to 44. 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. 1. First embodiment: solid-state imaging device 1-1 Overall configuration of solid-state imaging device 1-2 Configuration of main parts 1-3 Modifications 2. Second embodiment: solid-state imaging device 2-1 Configuration of main parts 2-2 Modifications 3. Third embodiment: Application example to electronic devices

[0010] 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. 44, 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.

[0011] The pixel region 2 includes a plurality of pixels 8 formed on a semiconductor substrate 12 and arranged in a two-dimensional array. Each pixel 8 includes a plurality of photoelectric conversion units 17 (see FIG. 2 ) and a plurality of pixel transistors. Examples of pixel transistors include a transfer transistor Tr (see FIG. 2 ), a reset transistor, an amplification transistor, and a selection transistor. The vertical drive circuit 3 is configured, for example, by a shift register, and sequentially selects each pixel 8 in the pixel region 2 row by row by, for example, sequentially outputting selection pulses to pixel drive wiring 9, and outputs pixel signals of the selected pixels 8 to the column signal processing circuit 4 through vertical signal lines 10. The pixel signals are signals obtained from charges (e.g., electrons) generated by the photoelectric conversion units 17.

[0012] 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. Examples of signal processing that can be used include correlated double sampling and AD (Analog-Digital) conversion to remove fixed pattern noise specific to pixels. 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 order, and causes the selected column signal processing circuit 4 to output the processed pixel signals to the horizontal signal line 11.

[0013] The output circuit 6 performs various signal processing operations on each pixel signal sequentially output from the column signal processing circuit 4 through the horizontal signal line 11. Examples of signal processing that can be used include various types of digital signal processing such as buffering, black level adjustment, and column variation correction. The control circuit 7 generates clock signals and control signals that serve as references for the operations of the vertical drive circuit 3, the column signal processing circuit 4, the 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, the column signal processing circuit 4, the horizontal drive circuit 5, etc.

[0014] [1-2 Configuration of Main Components] Next, the detailed structure of the solid-state imaging device 1 will be described. FIG. 2 is a diagram showing the cross-sectional configuration of the solid-state imaging device 1 when the semiconductor substrate 12 in FIG. 1 is cut along the row direction. As shown in FIG. 2, the solid-state imaging device 1 has a semiconductor substrate 12, and an insulating film 13, a color filter layer 14 (broadly speaking, an "optical filter layer"), and an on-chip lens layer 15 are stacked in this order on the light-receiving surface (hereinafter also referred to as the "back surface S1"; in a broad sense, the "first surface") of the semiconductor substrate 12. That is, the color filter layer 14 is stacked on the back surface S1 side of the semiconductor substrate 12. In addition, a wiring layer 16 is stacked on the surface of the semiconductor substrate 12 opposite the back surface S1 (hereinafter also referred to as the "front surface S2"; in a broad sense, the "second surface").

[0015] The semiconductor substrate 12 is a substrate made of, for example, silicon (Si). The semiconductor substrate 12 has a photoelectric conversion unit 17 formed in each region corresponding to each pixel 8. That is, the semiconductor substrate 12 has a plurality of photoelectric conversion units 17 arranged in a two-dimensional array. The photoelectric conversion unit 17 has a p-type semiconductor region and an n-type semiconductor region. The pn junction of these semiconductor regions forms a photodiode, generating charge according to the amount of light received. The photoelectric conversion unit 17 accumulates charge (e.g., electrons) generated by photoelectric conversion in the capacitance generated by the pn junction. The semiconductor substrate 12 also has trench isolation structures 18 formed in all regions between adjacent photoelectric conversion units 17. That is, the trench isolation structures 18 are formed in a lattice pattern in the semiconductor substrate 12 so as to surround each of the plurality of photoelectric conversion units 17. The trench isolation structures 18 are formed so as to penetrate the semiconductor substrate 12 from the back surface S1 to the front surface S2 of the semiconductor substrate 12. The trench isolation structure 18 has a trench portion 19 and an insulating film 13 disposed within the trench portion 19. The trench portion 19 penetrates the semiconductor substrate 12 from the back surface S1 to the front surface S2 of the semiconductor substrate 12, and its inner wall surface forms the outer shape of the trench isolation structure 18. By having the insulating film 13 inside, the trench isolation structure 18 can suppress the movement of charges (electrons) from one side to the other between adjacent photoelectric conversion units 17, thereby suppressing color mixing. Furthermore, the insulating film 13 continuously covers not only the inside of the trench portion 19 but also the back surface S1 of the semiconductor substrate 12. An example of a material for the insulating film 13 is silicon oxide (SiO).

[0016] The color filter layer 14 has color filters 20 (broadly speaking, "optical filters") arranged corresponding to each photoelectric conversion unit 17. That is, the color filters 20 are arranged in a two-dimensional array so that one color filter 20 is arranged for one photoelectric conversion unit 17. Examples of the color filters 20 include a red filter R that transmits red light, a green filter G that transmits green light, and a blue filter B that transmits blue light. The color filters 20 transmit light of a predetermined wavelength (red light, green light, blue light) for each type of color filter 20 and allow the transmitted light to enter the corresponding photoelectric conversion unit 17. For example, a Bayer array can be used as the arrangement pattern of the color filters 20. Waveguide wall units 21 and inter-pixel light-shielding films may be arranged between the color filters 20. The on-chip lens layer 15 has on-chip lenses 22 arranged corresponding to each photoelectric conversion unit 17. That is, the on-chip lenses 22 are arranged in a two-dimensional array such that one on-chip lens 22 is arranged for one photoelectric conversion unit 17 and one color filter 20. The on-chip lens 22 collects light (image light) from the subject via the imaging lens, and causes the collected light to enter the photoelectric conversion unit 17 via the color filter 20.

[0017] The wiring layer 16 has an interlayer insulating film 23 and wiring 24 stacked in multiple layers with the interlayer insulating film 23 interposed therebetween. Also, vias 25 extending in the thickness direction of the wiring layer 16 are formed in the wiring layer 16. The vias 25 electrically connect pixel transistors, floating diffusions, etc. formed on the semiconductor substrate 12 side to the wiring 24, etc. FIG. 2 illustrates an example in which the vias 25 electrically connect the transfer transistors Tr to the wiring 24. An example of a material for the vias 25 is polysilicon (polySi).

[0018] Furthermore, a reflective layer 26 that reflects light that has passed through the semiconductor substrate 12 toward the semiconductor substrate 12 (photoelectric conversion units 17) is formed on the semiconductor substrate 12 side of the wiring layer 16. The reflective layer 26 is formed between the interface between the wiring layer 16 and the semiconductor substrate 12 and the wiring 24 that is closest to the semiconductor substrate 12 among the multiple wirings 24. The reflective layer 26 and the semiconductor substrate 12, and the reflective layer 26 and the wiring 24, are separated by an interlayer insulating film 23. The reflective layer 26 also has a plurality of reflective units 27 that are arranged corresponding to the photoelectric conversion units 17. That is, as shown in FIG. 3 , the reflective units 27 are arranged in a two-dimensional array such that one reflective unit 27 is arranged for one photoelectric conversion unit 17. Specifically, the reflective units 27 are repeatedly arranged in each of two mutually orthogonal directions (row direction and column direction). Each reflective portion 27 is arranged so as to overlap a corresponding photoelectric conversion portion 17 in the stacking direction in which the semiconductor substrate 12 and the wiring layer 16 are stacked. In other words, the reflective layer 26 is configured so as to overlap at least a portion of the multiple photoelectric conversion portions 17 in the stacking direction. It can also be said that the reflective layer 26 is configured so as to be divided into multiple reflective portions 27 and arranged so as to be located at a position overlapping the photoelectric conversion portions 17 when viewed from the stacking direction. With this configuration, light that has passed through the corresponding photoelectric conversion portion 17, i.e., light that was not fully absorbed, is incident on each reflective portion 27.

[0019] 3 is a diagram showing the cross-sectional structure of the reflective layer 26 when cut along the line AA in FIG. 2. In FIG. 3, the reflective portion 27 corresponding to the photoelectric conversion portion 17 to which red light is incident by the color filter 20 is designated as "27 R ", and the reflecting portion 27 corresponding to the photoelectric conversion portion 17 on which the green light is incident is designated as "27 G ", and the reflecting portion 27 corresponding to the photoelectric conversion portion 17 on which blue light is incident is "27 B That is, in FIG. 3, the reflecting portion 27 B A color filter 20 that transmits blue light is disposed on the light receiving surface side of the reflecting portion 27. G A color filter 20 that transmits green light is disposed on the light receiving surface side of the reflecting portion 27. R3 illustrates a case where a color filter 20 that transmits red light is disposed on the light receiving surface side of the reflective portion 27. The planar shape of the reflective portion 27 is a rectangle that is slightly larger than the planar shape of the photoelectric conversion portion 17. In addition, in FIG. 3, the pixel that detects red light is referred to as a "red pixel 8". R ", and the pixel that detects green light is called "green pixel 8 G ", and the pixels that detect blue light are called "red pixels 8 R " he indicated.

[0020] Each reflector 27 forms a reflective metasurface including multiple microstructures 28 to reflect light that has passed through the photoelectric conversion unit 17. The multiple microstructures 28 are arranged in a two-dimensional array to avoid the positions of the vias 25. That is, the microstructures 28 are electrically isolated from the pixel transistors (transfer transistors Tr), floating diffusions, and wiring 24 of the solid-state imaging device 1, and are electrically floating. As a result, the microstructures 28 do not have a wiring function. For example, the microstructures 28 can be reflective elements that reflect incident light and can change the amplitude, phase, or both of the reflected light. As a result, when light that has passed through the photoelectric conversion unit 17 is incident on the reflector 27, it reflects the incident light back toward the photoelectric conversion unit 17. The dimensions of the microstructures 28 are approximately the same as the light incident on the microstructures 28 (visible light including red light, green light, and blue light, for example, light in the wavelength range of 600 nm to 700 nm). FIG. 3 illustrates an example in which the microstructure 28 is cylindrical, with the diameter of the microstructure 28 (cylinder) being approximately half the wavelength of the incident light. Also, as an example, all of the microstructures 28 of all of the reflecting portions 27 have the same shape. Furthermore, the material of the microstructure 28 can be, for example, an insulating material. Examples of insulating materials include tantalum oxide (Ta2O5), hafnium oxide (HfO2), titanium oxide (TiO2), zirconium oxide (ZrO2), barium titanate (BaTiO3), silicon oxide (SiO2), aluminum oxide (Al2O3), and magnesium oxide (MgO). In particular, when a Mie resonator (described later) is used as the microstructure 28, tantalum oxide (Ta2O5), hafnium oxide (HfO2), titanium oxide (TiO2), zirconium oxide (ZrO2), and barium titanate (BaTiO3) are preferred.

[0021] An example of the microstructure 28 (reflective element) may be a Mie resonator that excites Mie resonance inside the microstructure 28 when light is incident on the microstructure 28. Due to the Mie resonance, the microstructure 28 reflects light in a specific wavelength range (e.g., light in the visible light range including red light, blue light, and green light). The Mie resonance is a resonance phenomenon induced inside the microstructure 28. Conditions for exciting the Mie resonance include a refractive index of the microstructure 28 of 2 or more and a size of the microstructure 28 that is approximately half the design wavelength (e.g., the wavelength of light transmitted through the color filter 20 corresponding to the reflective portion 27). The wavelength range of light reflected by the Mie resonator can be controlled by adjusting the dimensions of the microstructure 28.

[0022] In the solid-state imaging device 1 having the above configuration, when light is incident from the back surface S1 side of the semiconductor substrate 12, the incident light passes through the on-chip lens 22 and undergoes photoelectric conversion in the photoelectric conversion unit 17, generating charges (e.g., electrons). The generated charges are then output as pixel signals from the vertical signal lines 10 (see FIG. 1 ) formed by the wiring 24 of the wiring layer 16. Here, for example, in a configuration without the reflective layer 26 (reflective unit 27) shown in FIG. 2 , if the semiconductor substrate 12 is thinned, the incident light may not be fully absorbed by the photoelectric conversion unit 17. The unabsorbed light may pass through the photoelectric conversion unit 17, resulting in a decrease in sensitivity. Furthermore, long-wavelength light has a low absorption rate due to silicon (Si) in the semiconductor substrate 12. Therefore, the decrease in sensitivity is particularly significant in the pixels 8 that detect light in the long-wavelength range (red light).

[0023] In contrast, the solid-state imaging device 1 according to the first embodiment includes a reflective layer 26 arranged to overlap at least some of the photoelectric conversion units 17 in the stacking direction of the semiconductor substrate 12 and the wiring layer 16, as shown in FIG. 2 . The reflective layer 26 also forms a reflective metasurface including a plurality of microstructures 28. As a result, for example, if the semiconductor substrate 12 is thinned and the photoelectric conversion units 17 are unable to absorb all of the incident light, the unabsorbed light passes through the photoelectric conversion units 17. The light that passes through the reflective layer 26 is then reflected by the reflective layer 26 toward the photoelectric conversion units 17 and then returns to the original photoelectric conversion units 17. This allows the transmitted light to be absorbed by the original photoelectric conversion units 17, improving sensitivity. This suppresses a decrease in sensitivity that accompanies thinning of the semiconductor substrate 12.

[0024] [1-3 Modifications] (1) In the first embodiment, an insulating material is used as the material for the microstructure 28. However, other configurations may also be employed. For example, as shown in FIGS. 4 and 5, a conductive material may be used as the material for the microstructure 28. FIG. 5 is a cross-sectional view of the reflective layer 26 taken along line B-B in FIG. 4. Examples of conductive materials include germanium (Ge), gallium nitride (GaN), cesium iodide (CSi), polysilicon (polySi), silicon carbide (SiC), silicon nitride (SiN), and amorphous silicon (aSi). As described above, polysilicon (polySi) is used as the material for the via 25. It is also generally used as the material for the gate electrode of a pixel transistor. Therefore, when polysilicon (p-Si) is used as the material for the microstructure 28, the microstructure 28 can be formed using existing equipment for manufacturing CMOS image sensors, and the reflective layer 26 can be easily formed. Also in this modification, a configuration using a Mie resonator can be adopted as the microstructure 28. In this case, the above-mentioned germanium (Ge) to amorphous silicon (aSi) can be adopted as the material of the Mie resonator.

[0025] (2) In the first embodiment, the microstructure 28 does not have a wiring function. However, other configurations may be employed. For example, as shown in FIGS. 6 and 7 , the microstructure 28 may have a wiring function. FIGS. 6 and 7 illustrate a configuration in which the microstructure 28 is electrically connected to one of the pixel transistors, floating diffusion, and wiring 24 of the solid-state imaging device 1 and also serves as wiring extending in the stacking direction of the semiconductor substrate 12 and the wiring layer 16. FIG. 7 is a diagram showing a cross-sectional configuration of the reflective layer 26 taken along line CC in FIG. 6 . Note that in FIGS. 6 and 7 , the number and density of the microstructures 28 are depicted at a low level for ease of viewing. However, in reality, the reflective layer 26 is configured to have a sufficient number and density to reflect light. Also, for ease of viewing, the microstructures 28 in FIG. 7 are depicted larger than the microstructures 28 in FIG. 6 . Similarly, in Figures 8 and 9 , in which modified examples of the solid-state imaging device 1 shown in Figures 6 and 7 are applied, the number, density, and size of the microstructures 28 are different from the actual configuration. Figures 6 and 7 illustrate a configuration in which the vias 25 shown in Figures 2 and 3 are modified and used as the microstructures 28. This eliminates the need to form the microstructures 28 and the vias 25 in separate processes, thereby suppressing an increase in the number of processes. Figures 6 and 7 illustrate a case in which the vias 25 (microstructures 28) electrically connect the pixel transistors (transfer transistors Tr) and the wiring 24. In this modified example, the dimensions of the vias 25 are approximately the same as the dimensions of the light incident on the vias 25. Figures 6 and 7 illustrate a case in which the microstructures 28 are prismatic, and the planar dimensions of the microstructures 28 (prismatic) are approximately half the wavelength of the incident light. The material of the microstructures 28 can be, for example, a conductive material. The conductive material may be, for example, the conductive material (germanium (Ge) to amorphous silicon (aSi)) described in modification (1). Also in this modification, a configuration using a Mie resonator as the via 25 (microstructure 28) can be employed. In this case, the above-described germanium (Ge) to amorphous silicon (aSi) can be employed as the material for the Mie resonator.

[0026] (3) In the first embodiment, the reflective portion 27 is formed for all pixels 8, but other configurations may also be employed. For example, as shown in FIGS. 8 and 9 , the reflective portion 27 (reflective layer 26) may be arranged to overlap only the photoelectric conversion portion 17 corresponding to the specific filter 29 in the stacking direction in which the semiconductor substrate 12 and the wiring layer 16 are stacked. The specific filter 29 may be a color filter 20 that transmits light in a specific wavelength range among a plurality of color filters 20 ("optical filters" in a broad sense). FIGS. 8 and 9 illustrate an example in which a red filter R is used as the specific filter 29. That is, the reflective portion 27 (reflective layer 26) is arranged to overlap only the pixel 8 (red pixel 8) that detects light in a specific wavelength range in the stacking direction. R Therefore, the pixel 8 (red pixel 8) that detects light in the super wavelength range, which has low absorption in silicon, is arranged to overlap only the photoelectric conversion portion 17 of the pixel 8 (red pixel 8). R ), that is, the reflective portion 27 is formed in the pixel 8 through which light easily passes. Therefore, it is possible to suppress a decrease in sensitivity, reduce the number of reflective portions 27, and simplify the structure of the wiring layer 16. Figures 8 and 9 show an example in which this is applied to the solid-state imaging device 1 shown in Figures 6 and 7. In Figures 8 and 9, the minute structures 28 (vias 25) shown in Figures 6 and 7 are modified into cylindrical shapes. Figure 9 is a diagram showing the cross-sectional structure of the reflective layer 26 when cut along line D-D in Figure 8.

[0027] (4) Although the first embodiment illustrates an example in which the reflective portion 27 is formed in the pixel 8 that detects visible light (red light, green light, and blue light), other configurations may also be employed. For example, as shown in FIGS. 10 , 11 , 12 , 13 , and 14 , the reflective portion 27 may be formed in the pixel 8 that detects infrared light. In this case, the reflective portion 27 (reflective layer 26) is configured to overlap with the photoelectric conversion portion 17 of the pixel 8 that detects infrared light, among the multiple photoelectric conversion portions 17, in the stacking direction in which the semiconductor substrate 12 and the wiring layer 16 are stacked. FIG. 10 illustrates an example in which the reflective portion 27 is applied to a SPAD pixel that detects light in the near-infrared region. In a SPAD pixel, the photoelectric conversion portion 17 constitutes a SPAD, and the SPAD pixel is used as a light receiving portion of an iTOF (indirect TOF), for example. Furthermore, FIGS. 11 , 12 , and 13 illustrate an example in which the reflective portion 27 is applied to an RGB+IR image sensor that detects light in a wide band. The RGB+IR image sensor has 8 red pixels arranged in a Bayer array. R , green pixel 8 G , blue pixel 8 B 8 green pixels out of G One of these is a pixel that detects infrared light (hereinafter referred to as "IR pixel 8"). IR 11 shows an image sensor in which red pixels 8 R , green pixel 8 G , blue pixel 8 B and IR pixel 8 IR 11 is a diagram showing a cross-sectional structure of the color filter 20 of the red pixel 8. R , green pixel 8 G and blue pixel 8 B 11 illustrates a configuration in which an infrared cut filter 30 is provided between a color filter 20 that transmits light in a corresponding wavelength range and a photoelectric conversion unit 17. IR However, as the color filter 20, an IR filter 20 that transmits infrared light is used. IR 1 shows an example of a configuration having an IR filter 20. IR is configured by laminating a color filter 20 that transmits red light and a color filter 20 that transmits blue light.

[0028] 12 and 13 are diagrams corresponding to FIG. 7 and show the cross-sectional structure of the reflective layer 26 of the RGB+IR image sensor. In FIGS. 12 and 13, the reflective portion 27 corresponding to the photoelectric conversion portion 17 onto which infrared light is incident is indicated as "27". IR 12 shows an example in which the same reflective portion 27 is formed for all the pixels 8. In addition, in FIG. 13, an example in which the same reflective portion 27 is formed for the red pixel 8 is shown. R , IR pixel 8 IR 13 shows a case where the reflective portion 27 is formed only in the red pixel 8. R Reflection portion 27 R and the IR pixel 8 IR Reflection portion 27 IR Each of the minute structures 28 constituting each pixel 8 (red pixel 8 R , IR pixel 8 IR In other words, the reflective layer 26 has dimensions adjusted in accordance with the detection wavelength of the first pixel (e.g., red pixel 8) that detects light in the first wavelength range. R ) overlapping with the photoelectric conversion unit 17 (reflection unit 27 R ) and the size of the minute structure 28 of the second pixel (for example, IR pixel 8) that detects light in a second wavelength range different from the first wavelength range. IR ) overlapping with the photoelectric conversion unit 17 (reflection unit 27 IR ) have different sizes from each other. R The size of the minute structure 28 constituting the reflective portion 27 of the IR pixel 8 IR The dimensions of the minute structure 28 that constitutes the reflecting portion 27 are as follows.

[0029] FIG. 14 illustrates an example in which the present invention is applied to an RGB-IR stacked image sensor that detects light over a wide band. The RGB-IR stacked image sensor is an image sensor in which a second semiconductor substrate 31 and a second wiring layer 32 are stacked in this order on the surface of the wiring layer 16 farther from the semiconductor substrate 12 (hereinafter also referred to as "surface S3"). The second semiconductor substrate 31 is a substrate made of, for example, indium gallium arsenide (InGaAs). Each region of the second semiconductor substrate 31 corresponding to each pixel 8 forms a second photoelectric conversion unit 33. The second photoelectric conversion unit 33 is a photoelectric conversion unit sensitive to near-infrared light (e.g., light in the wavelength range of 800 nm to 2500 nm). As a result, the second photoelectric conversion unit 33 receives near-infrared light that has passed through the semiconductor substrate 12 and the wiring layer 16 (including the reflective layer 26) and generates electric charges according to the amount of light received. The second wiring layer 32 has an interlayer insulating film 34 and wiring 35 stacked in multiple layers with the interlayer insulating film 34 interposed therebetween. Also, the second wiring layer 32 has vias 36 formed therein, which extend in the thickness direction of the second wiring layer 32. The vias 36 electrically connect pixel transistors, floating diffusions, etc. formed on the second semiconductor substrate 31 side to the wiring 35, etc.

[0030] Furthermore, a second reflective layer 37 is formed on the second semiconductor substrate 31 side of the second wiring layer 32. The second reflective layer 37 reflects near-infrared light that has passed through the second semiconductor substrate 31 toward the second semiconductor substrate 31 (second photoelectric conversion section 33). The second reflective layer 37 is formed between the interface between the second wiring layer 32 and the second semiconductor substrate 31 and the wiring 35 closest to the second semiconductor substrate 31 among the multiple wirings 35. The second reflective layer 37 and the second semiconductor substrate 31, and the second reflective layer 37 and the wiring 35 are spaced apart via an interlayer insulating film 34. The second reflective layer 37 also has a plurality of second reflective sections 38 arranged corresponding to the second photoelectric conversion sections 33. That is, as shown in FIG. 14 , the second reflective sections 38 are arranged in a two-dimensional array such that one second reflective section 38 corresponds to one second photoelectric conversion section 33. Each second reflector 38 is arranged to overlap with a corresponding second photoelectric conversion unit 33 in the stacking direction in which the second semiconductor substrate 31 and the second wiring layer 32 are stacked. As a result, near-infrared light that has passed through the corresponding second photoelectric conversion unit 33 is incident on each second reflector 38. Furthermore, the near-infrared light that has entered the second reflector 38 is reflected by the second reflector 38 and returned to the second photoelectric conversion unit 33. Therefore, the passed-through near-infrared light can be absorbed by the original second photoelectric conversion unit 33, thereby improving sensitivity. The second reflector 38 forms a reflective metasurface including a plurality of microstructures 39 so as to reflect near-infrared light that has passed through the second semiconductor substrate 31.

[0031] (5) In the first embodiment, the microstructure 28 has a cylindrical shape. However, other configurations may be used. For example, the microstructure 28 may have a rectangular prism shape as shown in FIG. 15, a cross prism shape as shown in FIG. 16, or a hollow cylinder shape as shown in FIG. 17. In this case, the dimensions of the microstructure 28 are set to a size that allows a reflective metasurface to be formed. For example, the dimensions are set to be approximately the same as the size of the light incident on the microstructure 28. Note that, as with the above-described modification example (2), FIGS. 15 to 17 illustrate a case in which a via 25 is used as the microstructure 28.

[0032] (6) In the first embodiment, all the microstructures 28 in the reflecting portion 27 have the same shape. However, other configurations may be employed. For example, as shown in FIGS. 18 and 19 , a single reflecting portion 27 may include multiple types of microstructures 28. FIG. 19 is a diagram illustrating a cross-sectional configuration of the reflecting layer 26 taken along line E-E in FIG. 18 . FIGS. 18 and 19 illustrate a case in which the dimensions of each microstructure 28 are adjusted for each reflecting portion 27 so that reflected light L is focused within the photoelectric conversion portion 17 that overlaps the reflecting portion 27. That is, the dimensions of each microstructure 28 in the reflecting layer 26 are adjusted so that reflected light L is focused within the photoelectric conversion portion 17 that overlaps the reflecting layer 26 (reflecting portion 27). This allows light that passes through the photoelectric conversion portion 17 to be efficiently absorbed by the original photoelectric conversion portion PD, thereby further improving sensitivity. 18 and 19 illustrate an example in which the arrangement pattern of the microstructures 28 in each reflecting section 27 is point-symmetrical with respect to the center of the reflecting section 27, and the reflected light L is focused at the center of the corresponding photoelectric conversion section 17. Focusing of the reflected light L is achieved by controlling the phase of the reflected light L for each microstructure 28. Note that, as with the above-described modified example (2), FIGS. 18 and 19 illustrate an example in which vias 25 are used as the microstructures 28.

[0033] (7) In the first embodiment, all the reflectors 27 have the same configuration. However, other configurations may be adopted. For example, each reflector 27 may have a configuration optimized for the image height (image plane position in a plan view). As an example, the dimensions of the microstructures 28 included in the reflectors 27 may be adjusted for each image height.

[0034] 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 therefore is not shown. FIG. 20 is a diagram corresponding to FIG. 2 of the first embodiment, and is a diagram showing a cross-sectional configuration of the solid-state imaging device 1 according to the second embodiment. FIG. 21 is a diagram corresponding to FIG. 3 of the first embodiment, and is a diagram showing a cross-sectional configuration of the light-shielding wall 40 when cut along line F-F in FIG. 20. In FIGS. 20 and 21, parts corresponding to those in FIGS. 2 and 3 are designated by the same reference numerals, and duplicated explanations will be omitted.

[0035] As shown in FIGS. 20 and 21 , 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 that the wiring layer 16 includes a light-shielding wall 40. The light-shielding wall 40 is formed in the entire region between adjacent reflecting portions 27. That is, the light-shielding wall 40 is formed in a lattice pattern on the wiring layer 16 so as to surround each of the plurality of reflecting portions 27. When viewed from the stacking direction in which the semiconductor substrate 12 and the wiring layer 16 are stacked, the planar shape of the light-shielding wall 40 is a line shape that continuously extends along the space between the reflecting portions 27. Furthermore, the light-shielding wall 40 is formed from the surface of the wiring layer 16 facing the semiconductor substrate 12 (hereinafter also referred to as the "rear surface S4") to the position of the wiring 24. In other words, when viewed from the stacking direction, the wiring layer 16 includes a light-shielding wall 40 that is formed between the reflecting portions 27 so as to divide the wiring layer 16 into a plurality of regions 41, and that blocks incident light from one of the adjacent regions 41 to the other. The light-shielding wall 40 is electrically connected to the floating diffusion and wiring 24 of the solid-state imaging device 1, and also serves as wiring extending in the stacking direction. That is, the light-shielding wall 40 has a wiring function. For example, the end of the light-shielding wall 40 on the back surface S4 side (the upper end in FIG. 20 ) is a side contact disposed in the trench isolation structure 18, and is electrically connected to the side contact connected to the floating diffusion. The light-shielding wall 40 can be made of, for example, a conductive material with light-shielding properties. Examples of conductive materials include tungsten (W), titanium (Ti), tantalum (Ta), nickel (Ni), molybdenum (Mo), chromium (Cr), iridium (Ir), platinum-iridium, titanium nitride (TiN), aluminum (Al), copper (Cu), and cobalt (Co).

[0036] Here, for example, in a configuration without the light-shielding wall 40 shown in FIG. 20 , at the high image height side where the angle of incidence (CRA) of light is large, light reflected by the reflecting portion 27 may travel obliquely and leak into the photoelectric conversion portion 17 of the pixel 8 located in the direction of the reflection destination, potentially resulting in optical color mixing. Furthermore, for example, light reflected by the wiring 24 may travel obliquely and leak into the photoelectric conversion portion 17 of the pixel 8 located in the direction of the reflection destination, potentially resulting in optical color mixing. Furthermore, long-wavelength light has a low absorption rate in silicon (Si) of the semiconductor substrate 12. Therefore, optical color mixing is particularly pronounced in pixels 8 adjacent to pixels 8 that detect light in the long-wavelength range (e.g., red light). In contrast, in the solid-state imaging device 1 according to the second embodiment, as shown in FIGS. 20 and 21 , the wiring layer 16 is configured to have a light-shielding wall 40 formed between adjacent reflecting portions 27 so that the wiring layer 16 is divided into multiple regions 41 when viewed from the stacking direction. Furthermore, the light-shielding wall 40 is configured to block incident light from one of the adjacent regions 41 to the other. As a result, for example, on the high image height side where the angle of incidence (CRA) of light is large, if light reflected by the reflecting unit 27 travels obliquely, or if light reflected by the wiring 24 travels obliquely, the obliquely traveling light is blocked by the light-shielding wall 40. This makes it possible to prevent the reflected light from leaking into the photoelectric conversion unit 17 of the pixel 8 located in the direction of the reflection destination, thereby suppressing optical color mixing.

[0037] [2-2 Modifications] (1) In the second embodiment, the light-shielding wall 40 is configured to have a wiring function. However, other configurations may also be employed. For example, as shown in FIGS. 22 and 23 , the light-shielding wall 40 may be configured without a wiring function. In FIGS. 22 and 23 , the light-shielding wall 40 may be electrically isolated from the floating diffusion and wiring 24 of the solid-state imaging device 1 and be electrically floating. FIG. 23 is a diagram showing a cross-sectional configuration of the light-shielding wall 40 taken along line G-G in FIG. 22 . The light-shielding wall 40 is formed from the back surface S4 of the wiring layer 16 to a position midway between the surface of the reflecting portion 27 facing the wiring 24 (hereinafter also referred to as the “front surface S5”) and the wiring 24. In this modification, the material of the light-shielding wall 40 may be, for example, a conductive material or an insulating material with light-shielding properties. Examples of insulating materials include oxide films such as tantalum oxide (Ta2O5), hafnium oxide (HfO2), titanium oxide (TiO2), zirconium oxide (ZrO2), barium titanate (BaTiO3), silicon oxide (SiO2), aluminum oxide (Al2O3), and magnesium oxide (MgO). When an oxide film is used, a light-shielding function can be obtained by, for example, the difference in refractive index at the interface between the oxide film and the interlayer insulating film 23. Also, as shown in FIG. 24, the light-shielding wall 40 shown in FIG. 23 may be divided at the intersections of the lattice, and vias 42 extending in the thickness direction of the wiring layer 16 may be formed at the divisions. The vias 42 electrically connect floating diffusions and the like formed on the semiconductor substrate 12 to the wiring 24 and the like. The material of the vias 42 may be, for example, a conductive material with light-shielding properties, similar to the material of the light-shielding wall 40 in the second embodiment. In this case, the view corresponding to Fig. 20 of the second embodiment, that is, the view showing the cross-sectional configuration of the solid-state imaging device 1, is the same as Fig. 22. Figs. 22 and 24 illustrate an example in which the via 42 has a rectangular columnar shape.

[0038] Furthermore, as shown in FIG. 25 , for example, the planar shape of the light-shielding wall 40 may be a plurality of dots aligned along the reflective portions 27 when viewed from the stacking direction. In this case, the view corresponding to FIG. 20 of the second embodiment, i.e., the view showing the cross-sectional configuration of the solid-state imaging device 1, is the same as FIG. 22 . FIGS. 22 and 25 illustrate a case where each dot is cylindrical. Furthermore, as shown in FIG. 26 , for example, the light-shielding wall 40 shown in FIG. 25 may be divided at the intersections of the lattice, and vias 43 extending in the thickness direction of the wiring layer 16 may be formed at the divisions. The vias 43 electrically connect floating diffusions and the like formed on the semiconductor substrate 12 side to the wiring 24 and the like. The material of the vias 43 may be, for example, a conductive material with light-shielding properties, similar to the material of the light-shielding wall 40 of the second embodiment. In this case, the view corresponding to FIG. 20 of the second embodiment, i.e., the view showing the cross-sectional configuration of the solid-state imaging device 1, is the same as FIG. 22 . 22 and 26 show an example in which the via 43 has a prismatic shape.

[0039] (2) Furthermore, in the second embodiment, an example was shown in which the light-shielding wall 40 was formed on the solid-state imaging device 1 shown in FIG. 2 of the first embodiment, i.e., the solid-state imaging device 1 using an insulating material as the material for the reflective layer 26. However, other configurations may also be adopted. For example, as shown in FIGS. 27 and 28 , the light-shielding wall 40 shown in FIG. 20 may be formed on the solid-state imaging device 1 shown in FIG. 4, i.e., the solid-state imaging device 1 using a conductive material as the material for the reflective layer 26. FIG. 28 corresponds to FIG. 21 of the second embodiment and shows a cross-sectional configuration of the light-shielding wall 40 taken along line H-H in FIG. 27 . Furthermore, for example, as shown in FIGS. 29 and 30 , the light-shielding wall 40 shown in FIGS. 22 and 23 may be formed on the solid-state imaging device 1 shown in FIG. 4. FIG. 30 shows a cross-sectional configuration of the light-shielding wall 40 taken along line I-I in FIG. 29 . Similarly, for example, the solid-state imaging device 1 shown in Fig. 4 may be configured to have the light-shielding walls 40 shown in Fig. 24, Fig. 25, and Fig. 26 formed thereon, as shown in Fig. 31, Fig. 32, and Fig. 33. In this case, the cross-sectional configuration of the solid-state imaging device 1 will be the same as Fig. 29.

[0040] (3) For example, as shown in FIGS. 34 and 35 , the solid-state imaging device 1 shown in FIG. 6 may be configured to have the light-shielding wall 40 shown in FIG. 20 formed on the solid-state imaging device 1 using a modified version of the via 25 shown in FIGS. 2 and 3 as the microstructure 28. FIG. 35 corresponds to FIG. 21 of the second embodiment and shows the cross-sectional configuration of the light-shielding wall 40 taken along line J-J in FIG. 34 . For example, as shown in FIGS. 36 and 37 , the solid-state imaging device 1 shown in FIG. 6 may be configured to have the light-shielding wall 40 shown in FIGS. 22 and 23 formed on the solid-state imaging device 1. FIG. 37 shows the cross-sectional configuration of the light-shielding wall 40 taken along line K-K in FIG. 36 . Similarly, for example, as shown in FIGS. 38 , 39 , and 40 , the solid-state imaging device 1 shown in FIG. 6 may be configured to have the light-shielding wall 40 shown in FIGS. 24 , 25 , and 26 formed on the solid-state imaging device 1. In this case, the cross-sectional configuration of the solid-state imaging device 1 is the same as that shown in FIG. 36 .

[0041] (4) Although the second embodiment has shown an example in which the light-shielding wall 40 is formed in the entire region between adjacent reflecting portions 27, other configurations may also be employed. For example, as shown in FIGS. 41 and 42 , the light-shielding wall 40 may be arranged to surround only the periphery of the reflecting portion 27 that is arranged to overlap the photoelectric conversion portion 17 corresponding to the specific filter 44 in the stacking direction in which the semiconductor substrate 12 and the wiring layer 16 are stacked. An example of the specific filter 44 is a color filter 20 that transmits light in a specific wavelength range among the multiple color filters 20. FIGS. 41 and 42 show an example in which a red filter R is used as the specific filter 44. That is, when viewed from the stacking direction, the light-shielding wall 40 is arranged to shield the pixels 8 (red pixels 8) that detect light in a specific wavelength range among the multiple reflecting portions 27. R Therefore, the pixel 8 (red pixel 8) that detects light in the super wavelength range, which has a low absorption rate in the photoelectric conversion unit 17 (silicon), is arranged to surround only the periphery of the reflecting unit 27 that is arranged to overlap with the photoelectric conversion unit 17 (silicon). R), that is, the light-shielding wall 40 is formed around the pixel 8 through which light can easily pass. As a result, optical color mixing can be suppressed, the number of light-shielding walls 40 can be reduced, and the structure of the wiring layer 16 can be simplified. Also, FIGS. 41 and 42 illustrate an example in which the present invention is applied to the solid-state imaging device 1 shown in FIGS. 34 and 35. In FIGS. 41 and 42, the minute structure 28 (via 25) is configured to be deformed into a cylindrical shape. FIG. 42 is a diagram showing the cross-sectional configuration of the light-shielding wall 40 when cut along line J-J in FIG. 41.

[0042] (5) For example, as shown in Fig. 43, the light-shielding walls 40 may be formed only in the outer peripheral region of the pixel region 2 (effective pixel region), and not in the central region. In this case, in a region away from the center of the pixel region 2 in one of the row direction and the column direction, the light-shielding walls 40 are arranged only between the reflective portions 27 lined up in one direction. For example, in a region away from the center in the row direction, the light-shielding walls 40 are arranged only between the reflective portions 27 lined up in the row direction. In Fig. 43, the light-shielding walls 40 are arranged only between the red pixel 8 and the red pixel 8 in the effective pixel region. R The reflecting portion 27 (27 R ) in the row direction and the reflective portion 27 (27 R ) located farther from the center of the pixel region 2 than the reflective portion 27 (27 R ) is shown as an example. Here, the absorption rate of long wavelength light by silicon (Si) of the semiconductor substrate 12 is low. Therefore, the amount of light passing through the photoelectric conversion unit 17 is small, especially for the pixels 8 that detect light in the long wavelength range (red pixels 8 R ) is larger. Therefore, the red pixel 8 R In this case, there is a high possibility that light will be reflected by the reflecting portion 27 and the wiring 24. Therefore, on the high image height side where the incident angle (CRA) of light is large, the red pixel 8 R Reflection portion 27 R and its reflecting portion 27 R By disposing the light-shielding wall 40 between the red pixel 8 and the reflective portion 27 located farther from the center of the pixel region 2 than the red pixel 8, R Reflection portion 27 R Light reflected by the red pixel 8 and traveling diagonally RThe light reflected by the wiring 24 and traveling obliquely can be blocked by the light blocking wall 40. Similarly, for example, in an area away from the center of the pixel area 2 in the column direction, the light blocking wall 40 is disposed only between the reflective portions 27 aligned in the column direction. In FIG. 43, the red pixel 8 R The reflecting portion 27 (27 R ) in the column direction and the reflective portion 27 (27 R ) located farther from the center of the pixel region 2 than the reflective portion 27 (27 R 43 illustrates a case where the via 25 is disposed only between the via 25 and the microstructure 28. In addition, Fig. 43 illustrates a case where the via 25 is applied to the solid-state imaging device 1 shown in Figs. 34 and 35. In Fig. 43, the microstructure 28 (via 25) is deformed into a cylindrical shape.

[0043] (6) 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.

[0044] 3. Third Embodiment The technology according to the present disclosure (the present technology) may be applied to various electronic devices. Fig. 44 is a diagram showing an example of a schematic configuration of an imaging device (digital still camera, video camera, etc.) as an electronic device to which the present technology is applied. As shown in Fig. 44, the imaging device 1000 includes a lens group 1001, a solid-state imaging device 1002 (solid-state imaging device 1 according to the first embodiment), a signal processing circuit 1003, a memory 1004, and a monitor 1005. The signal processing circuit 1003, the memory 1004, and the monitor 1005 are connected to each other via a bus line 1006.

[0045] 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 signal processing circuit 1003. The signal processing circuit 1003 then performs predetermined image processing on the pixel signal supplied from the solid-state imaging device 1002. The signal processing circuit 1003 then stores the processed image signal in a memory 1004 and displays an image of the subject on a monitor 1005 based on the image signal. The memory 1004 is composed of a flash memory or the like. The monitor 1005 is composed of a display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel.

[0046] 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 may also be adopted. For example, the solid-state imaging device 1 according to the second embodiment, the solid-state imaging device 1 according to the modified examples of the first and second embodiments, or another photodetector device to which the present technology is applied may be used.

[0047] The present technology can also be configured as follows. (1) A photodetector including a semiconductor substrate on which a plurality of pixels each having a photoelectric conversion unit are arranged, and a wiring layer stacked on a surface of the semiconductor substrate opposite to a light-receiving surface, the wiring layer being arranged to overlap with at least some of the photoelectric conversion units in a stacking direction in which the semiconductor substrate and the wiring layer are stacked, and having a reflective layer that reflects light that has passed through the semiconductor substrate toward the semiconductor substrate, the reflective layer forming a reflective metasurface including a plurality of microstructures. (2) The photodetector according to (1), in which the microstructure is electrically floating. (3) The photodetector according to (2), in which the material of the microstructure is an insulating material. (4) The photodetector according to (2), in which the material of the microstructure is a conductive material. (5) The photodetector according to (1), in which the microstructure also serves as wiring extending in the stacking direction. (6) The photodetector according to any of (1) to (5), wherein the reflective layer is arranged to overlap, in the stacking direction, the photoelectric conversion units of the plurality of photoelectric conversion units of a pixel that detects infrared light. (7) The photodetector according to any of (1) to (6), wherein the reflective layer has dimensions adjusted such that reflected light is condensed within the photoelectric conversion units that overlap the reflective layer. (8) (8-1) The photodetector according to any of (1) to (7), wherein the reflective layer is arranged to overlap, in the stacking direction, only the photoelectric conversion units of a pixel that detects light in a specific wavelength range. (8-2) A photodetector device according to any of (1) to (7), comprising an optical filter layer stacked on the light receiving surface side of the semiconductor substrate, the optical filter layer having a plurality of optical filters arranged corresponding to each of the photoelectric conversion units, which transmit light of a predetermined wavelength and allow it to be incident on the corresponding photoelectric conversion unit, and the reflective layer being arranged in the stacking direction so as to overlap only the photoelectric conversion unit corresponding to a specific filter among the plurality of optical filters that transmits light in a specific wavelength range.(9) The photodetector according to any one of (1) to (8), wherein the shape of the microstructure is a cylinder, a square pillar, a cross pillar, or a hollow cylinder. (10) The photodetector according to any one of (1) to (9), wherein the size of the microstructure in the reflective layer is different between a portion overlapping the photoelectric conversion unit of a first pixel that detects light in a first wavelength range and a portion overlapping the photoelectric conversion unit of a second pixel that detects light in a second wavelength range different from the first wavelength range. (11) The photodetector according to any one of (1) to (10), wherein the microstructure is a Mie resonator that excites Mie resonance. (12) The photodetector according to any one of (1) to (11), wherein the reflective layer is divided into a plurality of reflective sections and arranged so as to overlap the photoelectric conversion section when viewed from the stacking direction, and the wiring layer has a light-shielding wall formed between the reflective sections so that the wiring layer is divided into a plurality of regions when viewed from the stacking direction, and which blocks incident light from one of adjacent regions to another. (13) The photodetector according to (12), wherein the light-shielding wall is electrically floating. (14) The photodetector according to (12), wherein the light-shielding wall also serves as wiring extending in the stacking direction. (15) The photodetector according to any one of (12) to (14), wherein the planar shape of the light-shielding wall when viewed from the stacking direction is a line extending between the reflective sections or a plurality of dots lined up between the reflective layers. (16) (16-1) The light detection device according to any one of (12) to (15), wherein the light-shielding wall is arranged to surround only the periphery of the reflecting portion that is arranged to overlap the photoelectric conversion of a pixel that detects light in a specific wavelength range among the plurality of reflecting portions when viewed from the stacking direction.(16-2) The photodetector according to any of (12) to (15), further comprising an optical filter layer stacked on a light-receiving surface side of the semiconductor substrate, the optical filter layer having a plurality of optical filters arranged corresponding to the photoelectric conversion units and transmitting light of predetermined wavelengths to cause the light to be incident on the corresponding photoelectric conversion units, the plurality of optical filters including specific filters that transmit light of a specific wavelength range, and the light-shielding wall being arranged to surround only the periphery of the reflector arranged to overlap the photoelectric conversion unit corresponding to the specific filter when viewed from the stacking direction. (17) The photodetector according to any of (12) to (16), further comprising: an optical filter layer stacked on a light-receiving surface side of the semiconductor substrate, the optical filter layer having a plurality of optical filters arranged corresponding to the photoelectric conversion units, the plurality of optical filters including specific filters that transmit light of a specific wavelength range, ... (18) An electronic device comprising a photodetector device including a semiconductor substrate on which a plurality of pixels each having a photoelectric conversion unit are arranged, and a wiring layer stacked on the surface opposite to the light-receiving surface of the semiconductor substrate, the wiring layer being arranged so as to overlap with at least some of the photoelectric conversion units in the stacking direction in which the semiconductor substrate and the wiring layer are stacked, and having a reflective layer that reflects light that has passed through the semiconductor substrate toward the semiconductor substrate, and the reflective layer forming a reflective metasurface including a plurality of microstructures.

[0048] 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, 8 R ...red pixels, 8 G ...green pixels, 8 B ...blue pixels, 8 IR IR pixel, 9: pixel drive wiring, 10: vertical signal line, 11: horizontal signal line, 12: semiconductor substrate, 13: insulating film, 14: color filter layer, 15: on-chip lens layer, 16: wiring layer, 17: photoelectric conversion section, 18: trench isolation structure, 19: trench section, 20: color filter, 20 IR IR filter, 21: Waveguide wall portion, 22: On-chip lens, 23: Interlayer insulating film, 24: Wiring, 25: Via, 26: Reflecting layer, 27: Reflecting portion, 27R ...reflective part of blue pixel, 27 G ...reflective portion of green pixel, 27 B ...reflective part of red pixel, 27 IR ...reflecting portion of IR pixel, 28...microstructure, 29...specific filter, 30...infrared cut filter, 31...second semiconductor substrate, 32...second wiring layer, 33...second photoelectric conversion portion, 34...interlayer insulating film, 35...wiring, 36...via, 37...second reflective layer, 38...second reflective portion, 39...microstructure, 40...light-shielding wall, 41...region, 42...via, 43...via, 44...specific filter

Claims

1. A photodetector comprising: a semiconductor substrate on which a plurality of pixels having a photoelectric conversion section are arranged; and a wiring layer laminated on a surface side opposite to a light receiving surface of the semiconductor substrate, wherein the wiring layer is arranged so as to overlap at least a part of the plurality of photoelectric conversion sections in a stacking direction in which the semiconductor substrate and the wiring layer are laminated, and has a reflection layer that reflects light passing through the semiconductor substrate to the semiconductor substrate side, and the reflection layer forms a reflective metasurface including a plurality of microstructures.

2. The photodetector according to claim 1, wherein the microstructures are electrically floating.

3. The photodetector according to claim 2, wherein the material of the microstructures is an insulating material.

4. The photodetector according to claim 2, wherein the material of the microstructures is a conductive material.

5. The photodetector according to claim 1, wherein the microstructures also serve as wirings extending in the stacking direction.

6. The photodetector according to claim 1, wherein the reflection layer is arranged so as to overlap the photoelectric conversion section of a pixel that detects infrared light among the plurality of photoelectric conversion sections in the stacking direction.

7. The photodetector according to claim 1, wherein the dimensions of each of the microstructures are adjusted so that reflected light is condensed within the photoelectric conversion section overlapping the reflection layer.

8. The photodetector according to claim 1, wherein the reflection layer is arranged so as to overlap only the photoelectric conversion section of a pixel that detects light in a specific wavelength range in the stacking direction.

9. The photodetector according to claim 1, wherein the shape of the microstructures is cylindrical, quadrangular prism-shaped, cross-shaped prism-shaped, or hollow cylindrical.

10. The photodetector according to claim 1, wherein the size of the microstructures in a portion overlapping the photoelectric conversion section of a first pixel that detects light in a first wavelength range is different from the size of the microstructures in a portion overlapping the photoelectric conversion section of a second pixel that detects light in a second wavelength range different from the first wavelength range.

11. The photodetector according to claim 1, wherein the microstructures are Mie resonators that excite Mie resonance.

12. The reflective layer is divided into a plurality of reflective portions and arranged so as to be present at a position overlapping with the photoelectric conversion portion when viewed from the stacking direction. The wiring layer is formed between the reflective portions so that the wiring layer is divided into a plurality of regions when viewed from the stacking direction, and has a light shielding wall that shields incident light from one adjacent region to the other. The light detection device according to claim 1.

13. The light shielding wall is electrically floating. The light detection device according to claim 12.

14. The light shielding wall also serves as a wiring extending in the stacking direction. The light detection device according to claim 12.

15. When viewed from the stacking direction, the planar shape of the light shielding wall is a line shape extending along between the reflective portions or a plurality of dot shapes arranged along between the reflective layers. The light detection device according to claim 12.

16. The light shielding wall is arranged so as to surround only the periphery of the reflective portion that overlaps with the photoelectric conversion of the pixel that detects light in a specific wavelength range among the plurality of reflective portions when viewed from the stacking direction. The light detection device according to claim 12.

17. The reflective portions are repeatedly arranged in each of two directions orthogonal to each other. In a region away from the center of the pixel region in one of the two directions, the light shielding wall is arranged only between the reflective portions arranged in the one direction. The light detection device according to claim 12.

18. An electronic device comprising a semiconductor substrate on which a plurality of pixels having a photoelectric conversion portion are arranged, and a wiring layer laminated on the surface side opposite to the light receiving surface of the semiconductor substrate. The wiring layer is arranged so as to overlap at least a part of the plurality of photoelectric conversion portions in the stacking direction in which the semiconductor substrate and the wiring layer are laminated, and has a reflective layer that reflects the light passing through the semiconductor substrate to the semiconductor substrate side. The reflective layer forms a reflective metasurface including a plurality of microstructures. The electronic device includes a light detection device.

Images