Light detection device

Abstract

A light detection device according to one embodiment of the present disclosure comprises: a first semiconductor substrate in which a plurality of first pixels for detecting light in a first wavelength region are arranged in a two-dimensional array, and which has a first surface and a second surface that face each other; a second semiconductor substrate which is disposed on the first surface side of the first semiconductor substrate, and in which a plurality of second pixels for detecting light in a second wavelength region having a longer wavelength than the first wavelength region are arranged in a two-dimensional array; and a first optical member which is disposed on the second surface side of the first semiconductor substrate, includes a first refractive index section and a second refractive index section having a lower refractive index than the first refractive index section, and includes a plurality of annular regions from the centers of the second pixels, the plurality of regions having different ratios of the first refractive index section and the second refractive index section from each other, and the ratio of the first refractive index section increasing from the outer peripheries of the second pixels toward the centers.

Description

Light detection device 【0001】 This disclosure relates, for example, to a stacked type photodetector. 【0002】 For example, Patent Document 1 discloses a solid-state imaging device in which an alternating arrangement layer is placed on top of a semiconductor substrate having a photoelectric conversion unit, in which a high refractive index layer with a large refractive index and a low refractive index layer with a small refractive index are arranged alternately in the direction laterally with respect to the optical axis, and the layer is relatively thin compared to the optical length (lens length). 【0003】 Japanese Patent Publication No. 2009-15315 【0004】 Incidentally, in so-called stacked photodetectors, which consist of multiple semiconductor substrates stacked together and each having a photoconversion region for detecting light in different wavelength ranges, there is a need to improve quantum efficiency. 【0005】 It is desirable to provide a photodetector capable of improving quantum efficiency. 【0006】 An optical detection device according to one embodiment of the present disclosure comprises: a first semiconductor substrate having a first surface and a second surface, on which a plurality of first pixels for detecting light in a first wavelength range are arranged in a two-dimensional array; a second semiconductor substrate disposed on the first surface side of the first semiconductor substrate, on which a plurality of second pixels for detecting light in a second wavelength range with a longer wavelength than the first wavelength range are arranged in a two-dimensional array; and a first optical member disposed on the second surface side of the first semiconductor substrate, including a first refractive index portion and a second refractive index portion with a lower refractive index than the first refractive index portion, and having a plurality of annular regions extending from the center of the second pixel, where the ratio of the first refractive index portion to the second refractive index portion differs from that of the plurality of regions, and the ratio of the first refractive index portion increases from the outer periphery to the center of the second pixel. 【0007】In one embodiment of the light detection device of this disclosure, a first semiconductor substrate is stacked on which a plurality of first pixels for detecting light in a first wavelength range are arranged in a two-dimensional array, and a second semiconductor substrate is stacked on which a plurality of second pixels for detecting light in a second wavelength range with a longer wavelength than the first wavelength range are arranged in an array. A first optical member is arranged on the surface of the first semiconductor substrate opposite to the surface on which the second semiconductor substrate is stacked. This first optical member includes a first refractive index portion and a second refractive index portion with a lower refractive index than the first refractive index portion, and has a plurality of annular regions extending from the center of the second pixel. The plurality of regions are configured such that the ratio of the first refractive index portion to the second refractive index portion differs from one another, and the ratio of the first refractive index portion increases from the outer periphery of the second pixel towards the center. As a result, light in a predetermined wavelength range (light in the second wavelength range) from the light incident on the light detection device is focused to the center of the second pixel. 【0008】Figure 1 is a schematic cross-sectional view showing an example of the configuration of a photodetector according to an embodiment of the present disclosure. Figure 2A is a block diagram showing an example of the schematic configuration of the photodetector shown in Figure 1. Figure 2B is an explanatory diagram schematically showing an example of the configuration of the pixel array shown in Figure 2A. Figure 3 is an equivalent circuit diagram of the first pixel P1 shown in Figure 1. Figure 4 is an equivalent circuit diagram of the second pixel P2 shown in Figure 1. Figure 5 is a schematic plan view showing an example of the configuration of a subwavelength lens shown in Figure 1. Figure 6 is a schematic cross-sectional view of the subwavelength lens shown in Figure 5. Figure 7 is a diagram showing the configuration of the subwavelength lens shown in Figure 5 for visible light. Figure 8 is a diagram showing the configuration of the subwavelength lens shown in Figure 5 for near-infrared light. Figure 9 is a diagram showing an example of the arrangement of the subwavelength lenses shown in Figures 10A to 10H in the pixel array. Figure 10A is a schematic plan view showing an example of the configuration of a subwavelength lens arranged at position A shown in Figure 9. Figure 10B is a schematic plan view showing an example of the configuration of a subwavelength lens arranged at position B shown in Figure 9. Figure 10C is a schematic plan view showing an example configuration of a subwavelength lens placed at position C shown in Figure 9. Figure 10D is a schematic plan view showing an example configuration of a subwavelength lens placed at position D shown in Figure 9. Figure 10E is a schematic plan view showing an example configuration of a subwavelength lens placed at position E shown in Figure 9. Figure 10F is a schematic plan view showing an example configuration of a subwavelength lens placed at position F shown in Figure 9. Figure 10G is a schematic plan view showing an example configuration of a subwavelength lens placed at position G shown in Figure 9. Figure 10H is a schematic plan view showing an example configuration of a subwavelength lens placed at position H shown in Figure 9. Figure 11A is a schematic cross-sectional view showing an example of the manufacturing process of the subwavelength lens shown in Figure 5, etc. Figure 11B is a schematic cross-sectional view showing the process following Figure 11A. Figure 11C is a schematic cross-sectional view showing the process following Figure 11B. Figure 11D is a schematic cross-sectional view showing the process following Figure 11C. Figure 11E is a schematic cross-sectional view showing the process following Figure 11D. Figure 11F is a schematic cross-sectional diagram showing the process following Figure 1E. Figure 12 is a schematic cross-sectional diagram showing an example of the configuration of a typical stacked type photodetector and the manner in which incident light is focused. Figure 13 is a schematic cross-sectional diagram showing an example of the configuration of a typical stacked type photodetector and the manner in which incident light is focused.Figure 14 is a schematic cross-sectional diagram showing an example of the configuration of a typical stacked type photodetector and an example of the manner in which incident light is collected. Figure 15 is a schematic plan view showing an example of the configuration of the subwavelength lens shown in Figure 14. Figure 16 is a schematic cross-sectional diagram showing an example of the configuration of a photodetector according to Modification 1 of this disclosure. Figure 17 is a schematic plan view showing an example of the configuration of the subwavelength lens shown in Figure 16. Figure 18 is a schematic cross-sectional diagram showing an example of the configuration of a photodetector according to Modification 2 of this disclosure. Figure 19 is a schematic plan view showing an example of the configuration of the subwavelength lens shown in Figure 18. Figure 20 is a schematic cross-sectional diagram showing an example of the configuration of a photodetector according to Modification 3 of this disclosure. Figure 21 is a schematic plan view showing an example of the configuration of the subwavelength lens shown in Figure 20. Figure 22 is a schematic cross-sectional diagram showing an example of the configuration of a photodetector according to Modification 4 of this disclosure. Figure 23 is a schematic plan view showing an example of the configuration of the subwavelength lens shown in Figure 22. Figure 24 is a schematic cross-sectional diagram showing an example of the configuration of a photodetector according to Modification 5 of this disclosure. Figure 25 is a schematic plan view showing an example configuration of the subwavelength lens shown in Figure 24. Figure 26 is a schematic cross-sectional view showing an example configuration of a photodetector according to Modification 6 of this disclosure. Figure 27 is a schematic cross-sectional view showing an example configuration of a photodetector according to Modification 7 of this disclosure. Figure 28 is a schematic cross-sectional view showing an example configuration of a photodetector according to Modification 8 of this disclosure. Figure 29 is a schematic plan view showing an example configuration of the subwavelength lens shown in Figure 28. Figure 30 is a schematic cross-sectional view showing an example configuration of a photodetector according to Modification 9 of this disclosure. Figure 31 is a schematic plan view showing an example configuration of the subwavelength lens shown in Figure 30. Figure 32 is a schematic cross-sectional view showing an example configuration of a photodetector according to Modification 10 of this disclosure. Figure 33 is a schematic cross-sectional view showing an example configuration of a photodetector according to Modification 11 of this disclosure. Figure 34 is a schematic plan view showing an example configuration of the subwavelength lens shown in Figure 33. Figure 35 is a schematic cross-sectional view showing an example configuration of a photodetector according to Modification 12 of this disclosure. Figure 36 is a block diagram showing an example of the configuration of an electronic device using the photodetector shown in Figure 1. Figure 37A is a schematic diagram showing an example of the overall configuration of a photodetector system using the photodetector shown in Figure 1. Figure 37B is a diagram showing an example of the circuit configuration of the photodetector system shown in Figure 37A.Figure 38 is a functional block diagram showing an example of a rejection image device using the light detection device shown in Figure 1, etc. Figure 39 is a diagram showing an example of a schematic configuration of an endoscopic surgery system. Figure 40 is a block diagram showing an example of the functional configuration of a camera head and a CCU. Figure 41 is a block diagram showing an example of a schematic configuration of a vehicle control system. Figure 42 is an explanatory diagram showing an example of the installation position of an external information detection unit and an imaging unit. 【0009】 The embodiments of this disclosure will be described in detail below with reference to the drawings. The following description is one specific example of this disclosure, and this disclosure is not limited to the following embodiments. Furthermore, this disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc., of each component shown in each figure. The order of description is as follows: 1. Embodiment (An example of a photodetector in which a subwavelength lens having multiple regions with different ratios of low refractive index and high refractive index are arranged in an annular shape between a semiconductor substrate and an on-chip lens arranged on the light incident side in a stacked type photodetector) 2. Modifications 2-1. Modification 1 (Another example of the configuration of the photodetector) 2-2. Modification 2 (Another example of the configuration of the photodetector) 2-3. Modification 3 (Another example of the configuration of the photodetector) 2-4. Modification 4 (Another example of the configuration of the photodetector) 2-5. Modification 5 (Another example of the configuration of the photodetector) 2-6. Modification 6 (Another example of the configuration of the photodetector) 2-7. Modification 7 (Another example of the configuration of the photodetector) 2-8. Modification 8 (Another example of the configuration of the photodetector) 2-9. Modification 9 (Another example of the configuration of the photodetector) 2-10. Modification 10 (Another example of the configuration of the photodetector) 2-11. Modification 11 (Another example of the configuration of the photodetector) 2-12. Modification 12 (Another example of the configuration of the photodetector) 3. Application Examples 4. Application Examples 【0010】 <1. Embodiments> Figure 1 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1) according to an embodiment of the present disclosure. The light detection device 1 is applied to, for example, image sensors such as digital still cameras and video cameras, and distance image sensors that measure distance using the Time-of-Flight (ToF) method. 【0011】 The light detection device 1 is constructed by stacking a semiconductor substrate 11 on which a plurality of first pixels P1 for detecting light in the visible light region are arranged in a two-dimensional array, and a semiconductor substrate 21 on which a plurality of second pixels P2 for detecting light in the near-infrared region are arranged in an array. The semiconductor substrate 11 has a pair of opposing surfaces (first surface 11S1 and second surface 11S2), and the semiconductor substrate 21 is stacked on the first surface 11S1 side of the semiconductor substrate 11. The second surface 11S2 of the semiconductor substrate 11 is the light incident surface, and a subwavelength lens 40 is arranged on this second surface 11S2 side. The subwavelength lens 40 includes a low refractive index portion 41 and a high refractive index portion 42, and has a plurality of annular regions (zones Z1, Z2, Z3) extending from the center of the second pixels P2. Zones Z1, Z2, and Z3 are configured such that the ratio of the low refractive index portion 41 to the high refractive index portion 42 differs from one another, and the ratio of the high refractive index portion 42 increases from the outer edge to the center of the second pixel P2. 【0012】 Here, light in the visible light region corresponds to a specific example of "light in the first wavelength range" as one embodiment of the present disclosure, and light in the near-infrared region corresponds to a specific example of "light in the second wavelength range" as one embodiment of the present disclosure. The semiconductor substrate 11 corresponds to a specific example of "first semiconductor substrate" as one embodiment of the present disclosure, and the first pixel P1 corresponds to a specific example of "first pixel" as one embodiment of the present disclosure. The semiconductor substrate 21 corresponds to a specific example of "second semiconductor substrate" as one embodiment of the present disclosure, and the second pixel P2 corresponds to a specific example of "second pixel" as one embodiment of the present disclosure. The subwavelength lens 40 corresponds to a specific example of "first optical component" as one embodiment of the present disclosure. The high refractive index portion 42 corresponds to a specific example of "first refractive index portion" as one embodiment of the present disclosure, and the low refractive index portion 41 corresponds to a specific example of "second refractive index portion" as one embodiment of the present disclosure. 【0013】[Outline Configuration of the Photodetector] Figure 2A shows an example of the overall configuration of the photodetector 1 shown in Figure 1. The photodetector 1 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The photodetector 1 takes in incident light (image light) from a subject via, for example, an optical lens system, and converts the incident light, which is imaged on the imaging surface, into an electrical signal on a pixel-by-pixel basis and outputs it as a pixel signal. The photodetector 1 has, for example, a pixel array section 100 as an imaging area on a semiconductor substrate (specifically, a semiconductor substrate 11 or a semiconductor substrate 21), and a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and input / output terminals 116 arranged around the pixel array section 100. This photodetector 1 corresponds to one specific example of the "photodetector" in the embodiments of this disclosure. 【0014】 Figure 2B schematically represents one example configuration of the pixel array unit 100. As shown in Figure 2B, the pixel array unit 100 includes an effective region 100A having, for example, a plurality of unit pixels (specifically, a plurality of first pixels P1 or a plurality of second pixels P2) arranged in a matrix in two dimensions, and a peripheral region 100B located around the effective region 100A. The effective region 100A of the pixel array unit 100 is provided with a plurality of pixel rows, each composed of a plurality of first pixels P1 or a plurality of second pixels P2 arranged horizontally (horizontal direction of the paper), and a plurality of pixel columns, each composed of a plurality of first pixels P1 or a plurality of second pixels P2 arranged vertically (vertical direction of the paper). For example, one pixel drive line Lread (row selection line and reset control line) is wired to each pixel row in the pixel array unit 100, and one vertical signal line Lsig is wired to each pixel column. The pixel drive line Lread transmits drive signals for reading signals from each first pixel P1 or second pixel P2. The ends of multiple pixel drive lines Lread are connected to multiple output terminals corresponding to each pixel row of the vertical drive circuit 111. 【0015】The vertical drive circuit 111 is composed of a shift register, an address decoder, etc., and is a pixel drive unit that drives each first pixel P1 or second pixel P2 in the pixel array section 100, for example, on a pixel row basis. The signals output from each first pixel P1 or second pixel P2 of the pixel row selected and scanned by the vertical drive circuit 111 are supplied to the column signal processing circuit 112 through each of the vertical signal lines Lsig. 【0016】 The column signal processing circuit 112 is composed of amplifiers, horizontal selection switches, etc., provided for each vertical signal line Lsig. 【0017】 The horizontal drive circuit 113 is composed of a shift register, an address decoder, etc., and sequentially drives each horizontal selection switch of the column signal processing circuit 112 while scanning it. Through the selection scanning by this horizontal drive circuit 113, the signals of each first pixel P1 or second pixel P2 transmitted through each of the multiple vertical signal lines Lsig are sequentially output to the horizontal signal line 121 and transmitted to the outside of the semiconductor substrate 11 or semiconductor substrate 21 through the horizontal signal line 121. 【0018】 The output circuit 114 processes the signals sequentially supplied from each of the column signal processing circuits 112 via the horizontal signal line 121 and outputs them. The output circuit 114 may, for example, only perform buffering, or it may perform black level adjustment, column variation correction, and various digital signal processing. 【0019】 The circuit portion consisting of the vertical drive circuit 111, column signal processing circuit 112, horizontal drive circuit 113, horizontal signal line 121, and output circuit 114 may be formed directly on the semiconductor substrate 11 or semiconductor substrate 21, or it may be disposed on an external control IC. Furthermore, these circuit portions may be formed on other substrates connected by cables or the like. 【0020】The control circuit 115 receives a clock signal and data commanding the operating mode from outside the semiconductor substrate 11 or semiconductor substrate 21, and outputs data such as internal information of the first pixel P1 or second pixel P2, which are image sensors. The control circuit 115 also has a timing generator that generates various timing signals, and controls the drive of peripheral circuits such as the vertical drive circuit 111, the column signal processing circuit 112, and the horizontal drive circuit 113 based on the various timing signals generated by the timing generator. 【0021】 The input / output terminal 116 is used for exchanging signals with the outside. 【0022】 [Circuit Configuration of the Photodetector] (Readout Circuit of the First Pixel) Figure 3 shows an example of the readout circuit of the first pixel P1 of the photodetector 1 shown in Figure 1. The first pixel P1 includes, for example, a photoelectric conversion unit 12, a transfer transistor TR1, a floating diffusion FD1, a reset transistor RST1, an amplification transistor AMP1, and a selection transistor SEL1, as shown in Figure 3. 【0023】 The photoelectric conversion unit 12 is a photodiode (PD). The anode of the photoelectric conversion unit 12 is connected to the ground voltage line, and the cathode is connected to the source of the transfer transistor TR1. 【0024】 The transfer transistor TR1 is connected between the photoelectric conversion unit 12 and the floating diffusion FD1. A drive signal TRsig is applied to the gate electrode of the transfer transistor TR1, and the transfer transistor TR1 becomes active. When the transfer transistor TR1 becomes active, its transfer gate becomes conductive, and the signal charge accumulated in the photoelectric conversion unit 12 is transferred to the floating diffusion FD1 via the transfer transistor TR1. 【0025】The floating diffusion transistor FD1 is connected between the transfer transistor TR1 and the amplification transistor AMP1. The floating diffusion transistor FD1 converts the signal charge transferred by the transfer transistor TR1 into a voltage signal and outputs it to the amplification transistor AMP1. 【0026】 The reset transistor RST1 is connected between the floating diffusion FD1 and the power supply. A drive signal RSTsig is applied to the gate electrode of the reset transistor RST1, and the reset transistor RST1 becomes active. When the reset transistor RST1 is active, the reset gate of the reset transistor RST1 becomes conductive, and the potential of the floating diffusion FD1 is reset to the level of the power supply. 【0027】 The amplifying transistor AMP1 has its gate electrode connected to the floating diffusion FD1 and its drain electrode connected to the power supply, and serves as the input to the readout circuit for the voltage signal held by the floating diffusion FD1, a so-called source follower circuit. Specifically, the source electrode of the amplifying transistor AMP1 is connected to the vertical signal line Lsig via the selection transistor SEL1, thereby forming a source follower circuit with a constant current source connected to one end of the vertical signal line Lsig. 【0028】 The selection transistor SEL1 is connected between the source electrode of the amplification transistor AMP1 and the vertical signal line Lsig. The drive signal SELsig is applied to the gate electrode of the selection transistor SEL1, and the selection transistor SEL1 becomes active. When the selection transistor SEL1 is active, the selection gate of the selection transistor SEL1 becomes conductive, and the first pixel P1 becomes selected. As a result, the readout signal (pixel signal) output from the amplification transistor AMP1 is output to the vertical signal line Lsig via the selection transistor SEL1. 【0029】(Readout circuit for the second pixel) Figure 4 shows an example of the readout circuit for the second pixel P2 of the photodetector 1 shown in Figure 1. The second pixel P2 includes, for example, a photoelectric conversion unit 22, a transfer transistor TR2, an overflow gate OFG, a floating diffusion FD2, a reset transistor RST2, an amplification transistor AMP2, and a selection transistor SEL2, as shown in Figure 3. 【0030】 The photoelectric conversion unit 22 is a photodiode (PD). The anode of the photoelectric conversion unit 22 is connected to the ground voltage line, and the cathode is connected to the source of the transfer transistor TR2. 【0031】 The transfer transistor TR2 is connected between the photoelectric conversion unit 22 and the floating diffusion FD2. A drive signal TRsig is applied to the gate electrode of the transfer transistor TR2, and the transfer transistor TR2 becomes active. When the transfer transistor TR2 becomes active, its transfer gate becomes conductive, and the signal charge accumulated in the photoelectric conversion unit 22 is transferred to the floating diffusion FD2 via the transfer transistor TR2. 【0032】 The overflow gate OFG is connected between the photoelectric conversion unit 22 and the power supply unit. A drive signal OFGsig is applied to the gate electrode of the overflow gate OFG, and the overflow gate OFG becomes active. When the overflow gate OFG is active, the gate electrode of the overflow gate OFG becomes conductive, and the signal charge converted by the photoelectric conversion unit 22 is discharged to the power supply unit via the overflow gate OFG. 【0033】 The floating diffusion transistor FD2 is connected between the transfer transistor TR2 and the amplification transistor AMP2. The floating diffusion transistor FD2 converts the signal charge transferred by the transfer transistor TR2 into a voltage signal and outputs it to the amplification transistor AMP2. 【0034】The reset transistor RST2 is connected between the floating diffusion FD2 and the power supply unit. A drive signal RSTsig is applied to the gate electrode of the reset transistor RST2, and the reset transistor RST2 becomes active. When the reset transistor RST2 becomes active, the reset gate of the reset transistor RST2 becomes conductive, and the potential of the floating diffusion FD2 is reset to the level of the power supply unit. 【0035】 The amplification transistor AMP2 has its gate electrode connected to the floating diffusion FD2 and its drain electrode connected to the power supply unit, serving as the input part of a voltage signal reading circuit, namely a so-called source follower circuit, which holds the floating diffusion FD2. That is, the source electrode of the amplification transistor AMP2 is connected to the vertical signal line Lsig via the selection transistor SEL2, thereby forming a constant current source connected to one end of the vertical signal line Lsig and a source follower circuit. 【0036】 The selection transistor SEL2 is connected between the source electrode of the amplification transistor AMP2 and the vertical signal line Lsig. A drive signal SELsig is applied to the gate electrode of the selection transistor SEL2, and the selection transistor SEL2 becomes active. When the selection transistor SEL2 becomes active, the selection gate of the selection transistor SEL2 becomes conductive, and the second pixel P2 becomes selected. As a result, the read signal (pixel signal) output from the amplification transistor AMP2 is output to the vertical signal line Lsig via the selection transistor SEL2. 【0037】[Cross-sectional configuration of the light detection device] As shown in Figure 1, the light detection device 1 is a so-called vertical spectral type light detection device in which a first sensor substrate 10 and a second sensor substrate 20, each having a photoelectric conversion unit (photoelectric conversion unit 12, 22) that detects light in different wavelength ranges, are stacked in the vertical direction. In Figure 1, the stacking direction of the first sensor substrate 10 and the second sensor substrate 20 is the Z-axis direction, and the plane directions parallel to the stacking plane perpendicular to the Z-axis direction are the X-axis direction and the Y-axis direction. The X-axis direction, Y-axis direction and Z-axis direction are perpendicular to each other. 【0038】 The first sensor substrate 10 has a semiconductor substrate 11 having a pair of opposing surfaces (first surface 11S1 and second surface 11S2) and a multilayer wiring layer 51 provided on the first surface 11S1 side. The second sensor substrate 20, similar to the first semiconductor substrate, has a semiconductor substrate 21 having a pair of opposing surfaces (first surface 21S1 and second surface 21S2), a multilayer wiring layer 52 provided on the first surface 21S1 side and a multilayer wiring layer 53 provided on the second surface 21S2 side. The first sensor substrate 10 and the second sensor substrate 20 are stacked such that the first surface 11S1 of the first semiconductor substrate and the second surface 21S2 of the semiconductor substrate 21 face each other. Furthermore, the first sensor substrate 10 and the second sensor substrate 20 are electrically connected to each other by bonding together a plurality of pad electrodes 513, 533 embedded on the surfaces of the opposing multilayer wiring layers 51, 53. In other words, the first sensor substrate 10 and the second sensor substrate 20 are electrically connected to each other by a hybrid bond. A logic board 30 is laminated on the side of the second sensor substrate 20 opposite to the side that is bonded to the first sensor substrate 10. On the side of the first sensor substrate 10 opposite to the side that is bonded to the second sensor substrate 20, a subwavelength lens 40, a color filter 43, and an on-chip lens 44 are laminated in the Z-axis direction from the first sensor substrate 10 side. 【0039】(First Sensor Substrate) The first sensor substrate 10 has the semiconductor substrate 11 and the multilayer wiring layer 51 as described above. The semiconductor substrate 11 has, for example, a plurality of photoelectric conversion units 12, a plurality of floating diffusions FD1, and one or more transistors constituting the readout circuit shown in FIG. 3. As described above, on the semiconductor substrate 11, for example, a plurality of first pixels P1 for detecting light in the visible light region are arranged in a two-dimensional array. For example, for each first pixel P1, a photoelectric conversion unit 12, a floating diffusion FD1, and a readout circuit are provided respectively. The semiconductor substrate 11 further has a pixel isolation unit 13 that separates adjacent first pixels P1. 【0040】 The semiconductor substrate 11 is, for example, a silicon (Si) substrate and has a p-well in a predetermined region. 【0041】 The photoelectric conversion unit 12 is a photoelectric conversion element constituted by, for example, a PIN (Positive Intrinsic Negative) type photodiode (PD) and includes a pn junction formed in a predetermined region of the semiconductor substrate 11. The photoelectric conversion unit 12 detects, for example, light in the visible light region among the light incident on the light detection device 1, and generates and accumulates charges corresponding to the received light amount by photoelectric conversion. 【0042】 On the first surface 11S1 of the semiconductor substrate 11, for example, a floating diffusion FD1 and, as one or more transistors constituting the readout circuit shown in FIG. 3, for example, a transfer transistor TR1 are provided. The floating diffusion FD1 is a floating diffusion region that converts the charges transferred from the photoelectric conversion unit 12 via the transfer transistor TR1 into an electronic signal (for example, a voltage signal) and outputs it. The readout circuit shown in FIG. 3 is connected to the floating diffusion FD1. As shown in FIG. 1, the floating diffusion FD1 and the transfer transistor TR1 are formed, for example, between adjacent second pixels P2 in a plan view so as to avoid the optical path of the near-infrared region light (near-infrared light) L2 that condenses on the photoelectric conversion unit 22, which will be described later. 【0043】The pixel separation section 13 electrically separates adjacent first pixels P1 and is provided in a grid pattern on the pixel array section 100 so as to demarcate each of a plurality of first pixels P1 in a plan view, for example. The pixel separation section 13 extends between the first surface 11S1 and the second surface 11S2 of the semiconductor substrate 11 and penetrates the semiconductor substrate 11, for example. The pixel separation section 13 is composed of, for example, an insulating film 13A and a light-shielding film 13B embedded in the insulating film 13A. The pixel separation section 13 may be provided from the first surface 11S1 side of the semiconductor substrate 11, or it may be formed from the second surface 11S2 side of the semiconductor substrate 11. The light-shielding film 13B may be provided with an expanded portion 13X that is extended on the second surface 11S2 of the semiconductor substrate 11 for the purpose of suppressing the incidence of obliquely incident light between adjacent first pixels P1. 【0044】 The insulating film 13A is formed using, for example, silicon oxide (SiO). 【0045】 The light-shielding film 13B is formed using, for example, a conductive material having light-shielding properties. Examples of conductive materials having light-shielding properties include metallic materials such as tungsten (W), aluminum (Al), copper (Cu), cobalt (Co), nickel (Ni), or titanium (Ti), as well as silicon compounds. In addition, the light-shielding film 13B may be formed using polysilicon (Poly-Si). 【0046】The multilayer wiring layer 51 includes an interlayer insulating layer 511, within which one or more wiring layers 512 are formed, including the gate electrode TRG1 of the transfer transistor TR1 and wiring for transferring the signal charge read by the transfer transistor TR1 to the readout circuit. As shown in Figure 1, the gate electrode TRG1 of the transfer transistor TR1 and one or more wiring layers 512 are formed in a plan view, for example, between adjacent second pixels P2, so as to avoid the optical path of the near-infrared light L2 that is focused on the photoelectric conversion unit 22. The surface 51S of the interlayer insulating layer 511 is the bonding surface with the second sensor substrate 20. Multiple pad electrodes 513 are embedded in the surface 51S of the interlayer insulating layer 511. The multiple pad electrodes 513, like the gate electrode TRG1 of the transfer transistor TR1 and one or more wiring layers 512, are formed in a plan view, for example, between adjacent second pixels P2, so as to avoid the optical path of the near-infrared light L2 that is focused on the photoelectric conversion unit 22. 【0047】 The interlayer insulating layer 511 is composed of, for example, a single layer made of one of silicon oxide (SiO), TEOS, silicon nitride (SiN), and silicon oxynitride (SiON), or a laminated layer made of two or more of these materials. 【0048】 The gate electrode TRG1 and one or more wiring layers 512 of the transfer transistor TR1 are formed using, for example, aluminum (Al), copper (Cu), or tungsten (W). 【0049】 The multiple pad electrodes 513 are formed using, for example, copper (Cu). 【0050】(Second Sensor Substrate) The second sensor substrate 20 is an indirect TOF (hereinafter referred to as iTOF) sensor that acquires distance images (distance information) by time-of-flight (TOF). As described above, the second sensor substrate 20 has a semiconductor substrate 21 and multilayer wiring layers 52 and 53. The semiconductor substrate 21 has, for example, a plurality of photoelectric conversion units 22, a plurality of floating diffusion FD2s, and one or more transistors that constitute the readout circuit shown in Figure 4. On the semiconductor substrate 21, for example, a plurality of second pixels P2 that detect light in the near-infrared region are arranged in an array, and for example, a photoelectric conversion unit 22, a floating diffusion FD2, and a readout circuit are provided for each second pixel P2. The semiconductor substrate 21 further has a pixel separation unit 23 that separates adjacent second pixels P2. 【0051】 The semiconductor substrate 21 is, for example, a Si substrate and has p-wells in a predetermined region. In addition to a Si substrate, the semiconductor substrate 21 can be a silicon-germanium (Si-Ge) substrate which has a high absorption rate for light in the near-infrared region. Furthermore, the semiconductor substrate 21 can be an indium-gallium-arsenide (InGaAs) substrate or a germanium (Ge) substrate. 【0052】 The photoelectric conversion unit 22, like the photoelectric conversion unit 12, is a photoelectric conversion element composed of, for example, a PIN-type photodiode (PD), and includes a pn junction formed in a predetermined region of the semiconductor substrate 21. The photoelectric conversion unit 22 detects wavelengths in the near-infrared band, for example, from the light incident on the photodetector 1, and generates and stores a charge corresponding to the amount of light received by photoelectric conversion. 【0053】On the first surface 21S1 of the semiconductor substrate 21, for example, a floating diffusion FD2 and one or more transistors constituting the readout circuit shown in Figure 4, such as a transfer transistor TR2, are provided. The floating diffusion FD2 is a floating diffusion region that converts the charge transferred from the photoelectric conversion unit 22 into an electronic signal (for example, a voltage signal) and outputs it. The readout circuit shown in Figure 4 is connected to the floating diffusion FD2. 【0054】 The pixel separation section 23 electrically separates adjacent second pixels P2, and is provided in a grid pattern on the pixel array section 100 to partition each of a plurality of second pixels P2 in a plan view, for example. The pixel separation section 23 extends between the first surface 21S1 and the second surface 21S2 of the semiconductor substrate 21, and penetrates the semiconductor substrate 21, for example. The pixel separation section 23 is formed using an insulating film such as silicon oxide (SiO). 【0055】 The multilayer wiring layer 52 is provided on the first surface 21S1 side of the semiconductor substrate 21. The multilayer wiring layer 52 includes an interlayer insulating layer 521, and within the interlayer insulating layer 521, one or more wiring layers 522 are formed, including the gate electrode TRG2 of the transfer transistor TR2, and wiring for transferring the signal charge read by the transfer transistor TR2 and the voltage signal read from the first sensor substrate 10 to the readout circuit. 【0056】The multilayer wiring layer 53 is provided on the second surface 21S2 side of the semiconductor substrate 21. The multilayer wiring layer 53 includes an interlayer insulating layer 531, and within the interlayer insulating layer 531, one or more wiring layers 532 are formed, including wiring for transferring the voltage signal read from the first sensor substrate 10 to the readout circuit. As shown in Figure 1, the one or more wiring layers 532 are formed in a plan view, for example, between adjacent second pixels P2, so as to avoid the optical path of the near-infrared light L2 that is focused on the photoelectric conversion unit 22. The surface 53S of the interlayer insulating layer 531 is the bonding surface with the first sensor substrate 10. Multiple pad electrodes 533 are embedded in the surface 53S of the interlayer insulating layer 531. The multiple pad electrodes 533 are also formed in a plan view, for example, between adjacent second pixels P2, so as to avoid the optical path of the near-infrared light L2 that is focused on the photoelectric conversion unit 22, similar to the one or more wiring layers 512. Within the multilayer wiring layer 53, a wavelength d filter 534 is provided that cuts out light in the visible light region and transmits light in the near-infrared region. 【0057】 The interlayer insulating layers 521 and 531 are composed of a single layer made of one of the following materials: silicon oxide (SiO), TEOS, silicon nitride (SiN), and silicon oxynitride (SiON), or a laminated layer made of two or more of these materials. 【0058】 The gate electrode TRG2 and wiring layers 522 and 532 of the transfer transistor TR2 are formed using, for example, aluminum (Al), copper (Cu), or tungsten (W). 【0059】 The multiple pad electrodes 533 are formed using, for example, copper (Cu). 【0060】 In the light detection device 1, hybrid bonding is performed at the bonding surfaces of the first sensor substrate 10 and the second sensor substrate 20. Multiple pad electrodes 513 are exposed on the bonding surfaces of the first sensor substrate 10 and the second sensor substrate 20, respectively, and the first sensor substrate 10 and the second sensor substrate 20 are electrically connected to each other by bonding these together (for example, by CuCu bonding). 【0061】 A logic board 30 is bonded to the multilayer wiring layer 52. The logic board 30 has logic circuits formed on it, including, for example, a readout circuit for the first pixel P1 shown in Figure 3, a readout circuit for the second pixel P2 shown in Figure 4, the aforementioned vertical drive circuit 111, column signal processing circuit 112, horizontal drive circuit 113, output circuit 114, control circuit 115, and input / output terminals 116. 【0062】 The second sensor substrate 20 is further provided with a plurality of through electrodes 24. The plurality of through electrodes 24 penetrate the semiconductor substrate 21 and electrically connect the wiring layer 522 provided on the first surface 21S1 side of the semiconductor substrate 21 to the wiring layer 532 provided on the second surface 21S2 side. The voltage signal read from the first sensor substrate 10 is output to a readout circuit formed on the logic substrate 30 via these plurality of through electrodes 24. 【0063】 In the photodetector 1, the multiple first pixels P1 arranged in a two-dimensional array on the semiconductor substrate 11 and the multiple second pixels P2 arranged in a two-dimensional array on the semiconductor substrate 21 are arranged such that, for example, one second pixel P2 is stacked in the Z-axis direction for every four first pixels P1 arranged in a 2x2 grid. More specifically, in the photodetector 1, the outlines of the four first pixels P1 arranged in a 2x2 grid and the outline of one second pixel P2 are positioned at the same location in a plan view (see Figure 5). 【0064】 In such a light detection device 1, on the light incident side of the first sensor substrate 10 opposite to the bonding surface with the second sensor substrate 20, a subwavelength lens 40, a color filter 43, and an on-chip lens 44 are stacked in the Z-axis direction from the first sensor substrate 10 side, as described above. 【0065】The subwavelength lens 40 is for focusing light with a longer wavelength than visible light, such as near-infrared light, from the light incident from above onto the photoelectric conversion unit 22 embedded in the semiconductor substrate 21. The subwavelength lens 40 is arranged for each second pixel P2, and although the details will be described later, it has a configuration in which a plurality of low refractive index portions 41 and a plurality of high refractive index portions 42 are arranged alternately in an annular shape in the XY plane direction. The subwavelength lens 40 further has a plurality of annular regions (zones Z1, Z2, Z3) extending from the center of the second pixel P2. 【0066】 The color filter 43 selectively transmits light of a predetermined wavelength. The color filter 43 includes, for example, a red filter that selectively transmits red light (R), a green filter that selectively transmits green light (G), or a blue filter that selectively transmits blue light (B), and each color filter is arranged for each first pixel P1. For example, for four first pixels P1 arranged in a 2x2 grid, two green filters are placed diagonally, and one red filter and one blue filter are placed diagonally opposite each other. In multiple first pixels P1 provided with each color filter 43, for example, the corresponding color light is detected in each photoelectric conversion unit 12. That is, in the semiconductor substrate 11, multiple first pixels P1 are arranged in a Bayer pattern, with red pixels Pr that detect red light (R), green pixels Pg that detect green light (G), and blue pixels Pb that detect blue light (B). 【0067】The on-chip lens 44 is used to focus light in the visible light region, for example, from the light incident from above onto the photoelectric conversion unit 12 embedded in the semiconductor substrate 11, and corresponds to a specific example of the "second optical member" as one embodiment of the present disclosure. The on-chip lens 44 is formed using, for example, silicon oxide (SiO). The on-chip lens 44 is arranged for each first pixel P1, for example, similar to the color filter 43. In other words, the on-chip lens 44 is provided at the same pitch (a) as the plurality of first pixels P1 arranged in a two-dimensional array on the semiconductor substrate 11, and at half the pitch (a / 2) for the plurality of second pixels P2 arranged in a two-dimensional array on the semiconductor substrate 21. Note that the on-chip lens 44 has a small focusing effect on light in the near-infrared region because the first pixels P1 are generally on the order of wavelengths in the near-infrared region. 【0068】 (Subwavelength lens) Figure 5 schematically shows the planar configuration of the subwavelength lens 40 along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1 shown in Figure 1. Figure 6 schematically shows the cross-sectional configuration of the subwavelength lens 40 corresponding to the I-I' line shown in Figure 5. 【0069】The subwavelength lens 40 has, for example, three regions (zones Z1, Z2, Z3) in an annular shape from the center of the second pixel P2. In the photodetector 1, the center of the second pixel P2 coincides with the center of the four first pixels P1 arranged in a 2x2 grid stacked on the light incident side. Therefore, it can also be said that the subwavelength lens 40 has, for example, three regions (zones Z1, Z2, Z3) in an annular shape from the center of the four first pixels P1 arranged in a 2x2 grid. Zones Z1, Z2, and Z3 are configured such that the periods (duty cycle = high refractive index section 42 / low refractive index section 41) of the alternately arranged low refractive index sections 41 and high refractive index sections 42 are different from each other. The duty cycle within each zone Z1, Z2, and Z3 is configured to be uniform, and the duty cycle between each zone Z1, Z2, and Z3 is configured to increase from the outer circumference of the second pixel P2 toward the optical axis of the subwavelength lens 40, for example, toward the center of the second pixel P2. In other words, the duty cycle between the low refractive index portion 41 and the high refractive index portion 42 in each zone Z1, Z2, and Z3 is configured such that the ratio of the high refractive index portion 42 increases from the outer periphery of the second pixel P2 towards the center of the second pixel P2. To put it another way, within each zone Z1, Z2, and Z3, the high refractive index portion 42 has the same width, and between each zone Z1, Z2, and Z3, the width of the high refractive index portion 42 is configured to widen from the outer periphery of the second pixel P2 towards the center of the second pixel P2. 【0070】Zones Z1, Z2, and Z3 are configured such that the light focused by the on-chip lens 44 (for example, visible light L1) passes through one zone with a uniform duty cycle without crossing over to other zones. As described above, the photodetector 1 is arranged such that one second pixel P2 is stacked in the Z-axis direction for four first pixels P1 arranged in a 2x2 grid. An on-chip lens 44 is provided for each first pixel P1, and a subwavelength lens 40 is provided for each second pixel P2. The beam of visible light L1 focused by the on-chip lens 44 passes through, for example, zone Z2 of the three zones Z1, Z2, and Z3. The width of the zone Z2 through which the visible light L1 beam passes is, for example, as shown in Figure 5, larger than the spot size L1s of the visible light L1 beam passing through the subwavelength lens 40 (for example, about 700 nm if the visible light L1 is red light), and smaller than the wavelength of the light detected in the photoelectric conversion unit 22 (for example, near-infrared light L2) (for example, 1300 nm). 【0071】 Furthermore, the pitch between the low refractive index portion 41 and the high refractive index portion 42 that constitute zone Z2 through which the visible light L1 beam passes is less than or equal to the wavelength of the visible light L1 and the near-infrared light L2. 【0072】 Figure 7 shows an embodiment of the subwavelength lens 40 for visible light L1. Figure 8 shows an embodiment of the subwavelength lens 40 for near-infrared light L2. As described above, the photodetector 1 is arranged such that one second pixel P2 is stacked in the Z-axis direction for four first pixels P1 arranged in a 2x2 grid. For example, the multiple first pixels P1 have a square shape with sides of 1.3 μm, for example, equivalent to the wavelength of light in the near-infrared region, and the multiple second pixels P2 have a square shape with sides of 2.6 μm. 【0073】Light has a resolution approximately on the wavelength. As described above, the subwavelength lens 40 is configured such that the beam of visible light L1 focused by the on-chip lens 44 passes through a single zone with a uniform duty cycle (in this case, zone Z2). The pitch between the low refractive index portion 41 and the high refractive index portion 42 that constitute zone Z2 through which the beam of visible light L1 passes is less than or equal to the wavelength of visible light L1 and near-infrared light L2. Furthermore, the width of the zone through which the beam of visible light L1 passes is greater than the spot size L1s of the beam of visible light L1 and smaller than the wavelength of near-infrared light L2. Therefore, zone Z2 through which the beam of visible light L1 passes is not perceived by visible light L1 as a structure in which multiple low refractive index portions 41 and multiple high refractive index portions 42 are arranged alternately in an annular shape, but rather as a region with an averaged duty cycle. In other words, with respect to visible light L1, the subwavelength lens 40 functions as a parallel plate, as shown in Figure 7, for example. On the other hand, with respect to near-infrared light L2, the widths of each zone Z1, Z2, and Z3 are smaller than the wavelength of the near-infrared region. Therefore, the subwavelength lens 40 is recognized as a component with an averaged duty cycle, including zones Z1, Z2, and Z3, as shown in Figure 8, and functions as a phase difference lens. 【0074】 As a result, visible light L1 of the light incident on the light detection device 1 is bent toward the optical axis of the on-chip lens 44 on the curved surface of the on-chip lens 44, and then focused on the photoelectric conversion unit 12 embedded in the semiconductor substrate 11 for each first pixel P1, without being affected by the subwavelength lens 40. Near-infrared light L2 of the light incident on the light detection device 1 passes through the on-chip lens 44, then is bent toward the optical axis of the subwavelength lens 40, and focused on the photoelectric conversion unit 22 embedded in the semiconductor substrate 21 for each second pixel P2. 【0075】Furthermore, the floating diffusion FD1 formed on the first surface 11S1 of the semiconductor substrate 11, and the gate electrodes TRG1, 1 or more wiring layers 512, 532 and multiple pad electrodes 513, 533 of the transfer transistor TR1 formed in the multilayer wiring layers 51, 53 between the semiconductor substrate 11 and the semiconductor substrate 21, are formed in a plan view, for example, between adjacent second pixels P2, so as to avoid the optical path of near-infrared light L2 focused on the photoelectric conversion unit 22. More specifically, in a plan view, it is preferable to form them in the outermost region (for example, zone Z3) of the multiple regions (zones Z1, Z2, Z3) of the subwavelength lens 40. This reduces the loss of light due to the near-infrared light L2 being reflected or absorbed by the 1 or more wiring layers 512, 532, etc. 【0076】 The low refractive index portion 41 is, for example, silicon oxide (SiO ２ It can be formed using ). The low refractive index portion 41 has high transmittance of visible light L1 and near-infrared light L2, and other materials can be used if the refractive index is low. Other materials for the low refractive index portion 41 include, for example, magnesium fluoride (MgF ２ Examples include organic compounds such as polymethyl methacrylate (PMMA), polycarbonate (PC), and UV-curing resins. 【0077】 The high refractive index portion 42 is, for example, silicon nitride (Si ３ N ４ It can be formed using ). The high refractive index portion 42 has high transmittance of visible light L1 and near-infrared light L2, and other materials can be used as long as they have a high refractive index. Other materials for the high refractive index portion 42 include, for example, titanium oxide (TiO ２ ), niobium oxide (NbO ２ Examples include compound semiconductors such as ) or indium phosphide (InP). 【0078】 Table 1 shows an example of the configuration of the subwavelength lens 40. 【0079】 【0080】The sub-wavelength lens 40 can be configured, for example, such that the duty ratio of zone Z1 is 100%, the duty ratio of zone Z2 is 50%, and the duty ratio of zone Z3 is 0%. The low refractive index portion 41 is formed using, for example, SiO ２ (refractive index = 1.5). The high refractive index portion 42 is formed using, for example, Si ３ N ４ (refractive index = 2). The optical path length L of light is determined by the effective refractive index × lens thickness. The effective refractive index of zone Z2 with a duty ratio of 50% is 1.75 (refractive index of SiO ２ (1.5) × duty ratio (0.5) + refractive index of SiN (2.0) × duty ratio (0.5)). Thus, when the near-infrared light L2 passes through the sub-wavelength lens 40, a phase difference occurs, and the sub-wavelength lens 40 functions as a phase difference lens. Furthermore, the greater the difference in duty ratio between zones Z1, Z2, and Z3 of the sub-wavelength lens 40, the greater the phase difference of the light can be increased, and the lens strength (NA) can be designed to be larger. The thickness of the high refractive index portion 42 in the Z-axis direction is set so as to achieve a desired lens strength (NA). Since it becomes easier to create a phase difference as the thickness of the high refractive index portion 42 is increased, the lens strength (NA) can be increased. 【0081】 FIG. 9 shows an example of the arrangement in the pixel array portion 100 of the sub-wavelength lens shown in FIGS. 10A to 10H. FIGS. 10A to 10H schematically show configuration examples of the sub-wavelength lens 40 arranged at positions A to H shown in FIG. 9. 【0082】 In FIGS. 1, 5, etc., an example is shown where the centers of a plurality of low refractive index portions 41 and a plurality of high refractive index portions 42 arranged alternately in a ring shape in the XY plane direction coincide with the centers of four first pixels P1 and the centers of second pixels P2 arranged in 2 rows × 2 columns, but it is not limited thereto. The centers of the plurality of low refractive index portions 41 and the plurality of high refractive index portions 42 formed in a ring shape may be offset toward the center of the pixel array portion 100 (the direction of the arrow shown in FIG. 9) according to the position of the second pixel P2 in the plane of the pixel array portion 100. 【0083】For example, the subwavelength lens 40 provided in the second pixel P2 located in the upper left (position A) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are eccentrically offset downward to the right from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10A. For example, the subwavelength lens 40 provided in the second pixel P2 located in the upper center (position B) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are eccentrically offset downward from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10B. For example, the subwavelength lens 40 provided in the second pixel P2 located in the upper right (position C) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are eccentrically offset to the lower left from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10C. For example, the subwavelength lens 40 provided in the second pixel P2 located in the left center (position D) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are eccentrically offset to the right from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10D. For example, the subwavelength lens 40 provided in the second pixel P2 located in the right center (position E) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are offset to the left from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10E. For example, the subwavelength lens 40 provided in the second pixel P2 located in the lower left (position F) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are offset to the upper right from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10F.For example, the subwavelength lens 40 provided in the second pixel P2 located at the bottom center (position G) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are eccentric upward from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10G. For example, the subwavelength lens 40 provided in the second pixel P2 located at the bottom right (position H) of the pixel array section 100 shown in Figure 9 has a configuration in which the centers of the multiple low refractive index sections 41 and multiple high refractive index sections 42 are eccentric upward to the left from the centers of the four first pixels P1 and the second pixels P2 arranged in a 2x2 grid, as shown in Figure 10H. 【0084】 As a result, even if the angle of light incident on the subwavelength lens 40 changes between the center and periphery of the pixel array 100 due to the angle of view of the camera lens, near-infrared light L2 can be focused onto the photoelectric conversion unit 22 embedded in the semiconductor substrate 21. Similarly, the on-chip lens 44 can be shifted toward the center of the pixel array 100 according to the position of the first pixel P1 in the plane of the pixel array 100, thereby focusing visible light L1 onto the photoelectric conversion unit 12 embedded in the semiconductor substrate 11. As a result, the light detection device 1 can reduce the image height dependence of its focusing characteristics, such as sensitivity. 【0085】 The subwavelength lens 40 can be manufactured, for example, as follows. 【0086】 First, as shown in Figure 11A, a silicon nitride film 42X is deposited on the second surface 11S2 of the semiconductor substrate 11. Next, as shown in Figure 11B, a resist film 61 is coated onto the silicon nitride film 42X. Subsequently, as shown in Figure 11C, the resist film 61 is patterned using photolithography technology. 【0087】Next, as shown in Figure 11D, the silicon nitride film 42X is processed using the resist film 61 as a mask, for example by dry etching. This forms the multiple high refractive index portions 42 described above. Subsequently, as shown in Figure 11E, the resist film 61 is removed. Finally, as shown in Figure 11F, a low refractive index portion 41 is formed, for example, a silicon oxide film is deposited to fill the multiple high refractive index portions 42, and then the surface is planarized by chemical mechanical polishing (CMP), for example. With these steps, the subwavelength lens 40 shown in Figure 1 is completed. 【0088】 [Function and Effects] In this embodiment, the light detection device 1 has a configuration in which a semiconductor substrate 11 on which a plurality of first pixels P1 are arranged in a two-dimensional array and a semiconductor substrate 21 on which a plurality of second pixels P2 are arranged in an array are stacked, and the subwavelength lens 40 is positioned on the side of the semiconductor substrate 11 that is the light incident surface (second surface 11S2) opposite to the side on which the semiconductor substrate 21 is stacked. The plurality of first pixels P1 detect light in the visible light region, for example, and the plurality of second pixels P2 detect light in the near-infrared region, for example. The subwavelength lens 40 includes a low refractive index portion 41 and a high refractive index portion 42 and has a plurality of annular regions (zones Z1, Z2, Z3) extending from the center of the second pixel P2. Zones Z1, Z2, and Z3 have different ratios of low refractive index portion 41 and high refractive index portion 42, and are configured such that the ratio of high refractive index portion 42 increases from the outer periphery of the second pixel P2 towards the center. As a result, the near-infrared light from the light entering the light detector 1 is focused onto the second pixel P2. This will be explained below. 【0089】Figure 12 schematically shows an example of a cross-sectional configuration of a typical stacked type photodetector (photodetector 1000A), similar to the photodetector 1 of this embodiment. In this configuration, a first semiconductor substrate 1011 on which a plurality of first pixels P1 for detecting visible light L1 are arranged in a two-dimensional array, and a second semiconductor substrate 1021 on which a plurality of second pixels P2 for detecting near-infrared light L2 are arranged in an array, are stacked. In the photodetector 1000A, the first semiconductor substrate 1011, the second semiconductor substrate 1021, and the logic substrate 1030 are stacked in this order from the light incident side. Multilayer wiring layers 1051 and 1052 are provided between the first semiconductor substrate 1011 and the second semiconductor substrate 1021, and between the second semiconductor substrate 1021 and the logic substrate 1030, respectively. On the light incident surface side of the first semiconductor substrate 1011, opposite to the side on which the second semiconductor substrate 1021 is stacked, a protective layer 1045, a color filter 1043, and an on-chip lens 1044 are provided in this order from the first semiconductor substrate 1011 side. Similar to the light detection device 1 of this embodiment, for example, a plurality of first pixels P1 have a square shape with one side of 1.3 μm, which is equivalent to the wavelength of light in the near-infrared region, and a plurality of second pixels P2 have a square shape with one side of 2.6 μm, and one second pixel P2 is stacked for every four first pixels P1 arranged in a 2x2 grid. An on-chip lens 1044 is provided for each first pixel P1. 【0090】Of the light incident on the photodetector 1000A, visible light L1 and near-infrared light L2 are focused as shown in Figure 12. Specifically, visible light L1 is focused on the photoelectric conversion unit 1012 embedded in the first semiconductor substrate 1011 by the on-chip lens 1044. On the other hand, for near-infrared light L2, the lens effect of the on-chip lens 1044, which is provided for each first pixel P1 of the same size as the wavelength of near-infrared light L2, is small. Therefore, near-infrared light L2 is focused at a deeper position than visible light L1 along the optical axis of the on-chip lens 1044 (for example, near the surface of the second semiconductor substrate 1021 facing the logic substrate 1030, as shown in Figure 12). As described above, a multilayer wiring layer 1051 is provided between the first semiconductor substrate 1011 and the second semiconductor substrate 1021. A portion of the near-infrared light L2 focused by the optical axis of the on-chip lens 1044 is reflected or absorbed by the wiring (e.g., wiring 1521) formed on the multilayer wiring layer 1051. As a result, the amount of near-infrared light L2 incident on the second semiconductor substrate 1021 decreases. Furthermore, in the photodetector 1000A, since the near-infrared light L2 is focused by the optical axis of the on-chip lens 1044 as described above, it is incident on the periphery of each second pixel P2 rather than the center. If the second pixel P2 is configured as a single-photon avalanche diode (SPAD) pixel, if there is a large amount of charge photoelectrically converted at the periphery of the pixel, the charge transfer path to the multiplication section provided in the center of the pixel becomes longer, which raises concerns about worsening timing jitter. 【0091】Figure 13 schematically shows another example of a cross-sectional configuration of a typical stacked type photodetector (photodetector 1000B). Photodetector 1000B has the same configuration as photodetector 1000A, except that a subwavelength lens 1040A is placed between the light incident surface of the first semiconductor substrate 1011 and the color filter 1043 for each first pixel P1. The subwavelength lens 1040A has a low refractive index layer 1041 and a high refractive index layer 1042 arranged alternately, and the width of the high refractive index layer 1042 is configured to gradually increase from the outer edge to the center of the first pixel P1. In photodetector 1000B equipped with such a subwavelength lens 1040A, as shown in Figure 13, only the focal length changes, and the reduction in the amount of near-infrared light L2 due to reflection or absorption by wiring (e.g., wiring 1521) formed on the multilayer wiring layer 1051, and the deterioration of timing jitter characteristics are not improved. 【0092】 Figure 14 schematically shows another example of the cross-sectional configuration of a typical stacked type photodetector (photodetector 1000C). Figure 15 is a schematic plan view showing an example of the configuration of the subwavelength lens 1040B shown in Figure 14. The photodetector 100C has the same configuration as the photodetector 1000B, except that a subwavelength lens 1040B is placed between the light incident surface of the first semiconductor substrate 1011 and the color filter 1043 for each second pixel P2. As shown in Figure 15, the subwavelength lens 1040B has low refractive index layers 1041 and high refractive index layers 1042 arranged alternately, and the width of the high refractive index layer 1042 is configured to gradually increase from the outer edge to the center of the second pixel P2, similar to the subwavelength lens 1040A, as shown in Figure 15, for example. In the photodetector 1000C, since a subwavelength lens 1040B is placed for each second pixel P2, near-infrared light L2 is focused to the center of each second pixel P2. However, as shown in Figure 14, visible light L1 is also bent toward the optical axis of the subwavelength lens 1040B. Therefore, crosstalk due to leakage of visible light L1 to adjacent pixels is a concern. 【0093】In contrast, in this embodiment, a subwavelength lens 40 is arranged on the side of the semiconductor substrate 11 that is the light incident surface (second surface 11S2) opposite to the side on which the semiconductor substrate 21 is stacked (the second surface 11S2), and which includes a low refractive index portion 41 and a high refractive index portion 42, and has multiple regions (zones Z1, Z2, Z3) in an annular shape from the center of the second pixel P2. As described above, zones Z1, Z2, and Z3 are configured such that the ratio of the low refractive index portion 41 to the high refractive index portion 42 differs from each other, and the ratio of the high refractive index portion 42 increases from the outer periphery to the center of the second pixel P2. As a result, light in the near-infrared region is focused to the center of the second pixel P2 without degrading the light-gathering characteristics of the visible light region among the light incident on the light detection device 1. 【0094】 As a result of the above, the photodetector 1 of this embodiment can improve quantum efficiency. 【0095】 Furthermore, in the photodetector 1 of this embodiment, the floating diffusion FD1, transfer transistor TR1, one or more wiring layers 512, 532, and multiple pad electrodes 513, 533 formed between the semiconductor substrate 11 and the semiconductor substrate 21 are formed in the outermost region (for example, zone Z3) of the multiple regions (zones Z1, Z2, Z3) of the subwavelength lens 40 in a plan view. This reduces the loss of light intensity due to the reflection or absorption of near-infrared light focused on the second pixel P2 by the subwavelength lens 40 by the one or more wiring layers 512, 532, etc. 【0096】 Next, embodiments and modified examples 1 to 12 of this disclosure, as well as application examples and application examples, will be described. In the following, components similar to those in the above embodiments will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate. 【0097】<2. Modifications> (2-1. Modification 1) Figure 16 schematically shows an example of the cross-sectional configuration of the photodetector (photodetector 1A) according to Modification 1 of the present disclosure. Figure 17 schematically shows the planar configuration of the subwavelength lens 40A along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1A shown in Figure 16. Note that Figure 16 represents a cross-section corresponding to the line II-II' shown in Figure 17. The photodetector 1A is applied to image sensors such as those in digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method, similar to the photodetector 1 of the above embodiment. 【0098】 In the above embodiment, the subwavelength lens 40 was shown, for example, as shown in Figure 5, in which the periodic pattern of a plurality of low refractive index portions 41 and a plurality of high refractive index portions 42 arranged alternately in an annular shape in the XY plane direction is substantially circular, but it is not limited to this. The modified photodetector 1A includes, for example, a subwavelength lens 40A in which the periodic pattern of a plurality of low refractive index portions 41 and a plurality of high refractive index portions 42 arranged alternately in an annular shape in the XY plane direction is substantially square, as shown in Figure 17. Except for this point, the photodetector 1A has substantially the same configuration as the photodetector 1 of the above embodiment. 【0099】 Even with this configuration, the modified photodetector 1A can achieve the same effects as the embodiment described above. 【0100】 Furthermore, the subwavelength lens 40A of this modified example has improved light-gathering performance compared to the subwavelength lens 40 of the above embodiment, as the zone width in the opposite side direction is narrower. Therefore, the photodetector 1A of this modified example can further reduce the loss of light due to the reflection or absorption of near-infrared light L2 in the wiring layers (for example, wiring layers 512, 532) provided in the opposite side direction, compared to the photodetector 1 of the above embodiment. 【0101】(2-2. Modification 2) Figure 18 schematically shows an example of the cross-sectional configuration of the photodetector (photodetector 1B) according to Modification 2 of the present disclosure. Figure 19 schematically shows the planar configuration of the subwavelength lens 40B along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1B shown in Figure 18. Note that Figure 18 represents a cross-section corresponding to the line III-III' shown in Figure 19. The photodetector 1B, like the photodetector 1 of the above embodiment, is applied to, for example, image sensors such as digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method. 【0102】 In the above embodiment and modification 1, an example was shown in which one second pixel P2 is stacked on top of four first pixels P1 arranged in a 2x2 grid, and zones Z1, Z2, and Z3 are provided in an annular shape from the center of the four first pixels P1 arranged in a 2x2 grid, which coincide with the center of the second pixel P2. However, the invention is not limited to this. In this modification, the photodetector 1B is equipped with a subwavelength lens 40B in which, for example, one second pixel P2 is stacked on top of nine first pixels P1 arranged in a 3x3 grid, and zones Z1, Z2, and Z3 are provided in an annular shape from the center of one first pixel P1 located in the center of the nine first pixels P1 arranged in a 3x3 grid, which coincides with the center of the second pixel P2. Except for this point, the photodetector 1B has substantially the same configuration as the photodetector 1 of the above embodiment. 【0103】The subwavelength lens 40B has annular zones Z1, Z2, and Z3, similar to the embodiments described above. In the subwavelength lens 40B, the width of zone Z1, which is closest to the optical axis, is wider than the first pixel P1, as shown in Figure 19. In other words, the width of zone Z1 of the subwavelength lens 40B is greater than the wavelength of light in the near-infrared region. On the other hand, the widths of zones Z2 and Z3 of the subwavelength lens 40B are smaller than the wavelength of light in the near-infrared region, similar to zones Z2 and Z3 of the subwavelength lens 40. Of the near-infrared light L2 passing through the subwavelength lens 40B having such a configuration, the near-infrared light L2 incident on zone Z1 passes through without being bent by the subwavelength lens 40B, as shown in Figure 18. On the other hand, the near-infrared light L2 incident on zones Z2 and Z3 is bent by the subwavelength lens 40B and focused toward the center of the second pixel P2, as shown in Figure 18. 【0104】 Even with this configuration, the modified photodetector 1B can achieve the same effects as the embodiment described above. 【0105】 (2-3. Modification 3) Figure 20 schematically shows an example of the cross-sectional configuration of the photodetector (photodetector 1C) according to Modification 3 of the present disclosure. Figure 21 schematically shows the planar configuration of the subwavelength lens 40C along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1C shown in Figure 20. Note that Figure 20 represents a cross-section corresponding to the IV-IV' line shown in Figure 21. The photodetector 1C, like the photodetector 1 of the above embodiment, is applied to, for example, image sensors such as digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method. 【0106】In the above embodiment and modification 1, an example was shown in which one second pixel P2 is stacked on top of four first pixels P1 arranged in a 2x2 grid, and zones Z1, Z2, and Z3 are provided in an annular shape from the centers of the four first pixels P1 arranged in a 2x2 grid, which coincide with the center of the second pixel P2. However, the invention is not limited to this. In this modification, the photodetector 1C is equipped with a subwavelength lens 40C in which, for example, one second pixel P2 is stacked on top of two first pixels P1 arranged in a 1x2 grid, and zones Z1, Z2, and Z3 are provided in an annular shape from the centers of two adjacent first pixels P1 that coincide with the center of the second pixel P2. Except for this point, the photodetector 1C has substantially the same configuration as the photodetector 1 of the above embodiment. 【0107】 In the modified photodetector 1C, the second pixel P2 has a horizontally elongated shape corresponding to two first pixels P1 arranged in a 1x2 grid, and the subwavelength lens 40C has annular zones Z1, Z2, and Z3, similar to the above embodiment. The subwavelength lens 40C has, for example, widths W1x of zone Z1 in the X-axis direction and W1y of zone Z1 in the Y-axis direction, widths W2x of zone Z2 in the X-axis direction and W2y of zone Z2 in the Y-axis direction, and widths W3x of zone Z3 in the X-axis direction and W3y of zone Z3 in the Y-axis direction, which are different from each other. Specifically, the widths W1y, W2y, and W3y of each zone Z1, Z2, and Z3 in the Y-axis direction are narrower than the widths W1x, W2x, and W3x of each zone Z1, Z2, and Z3 in the X-axis direction. Furthermore, in the subwavelength lens 40C, for example, the periods (duty cycles) of the multiple low refractive index sections 41 and multiple high refractive index sections 42 arranged alternately in the X-axis direction are different from those of the multiple low refractive index sections 41 and multiple high refractive index sections 42 arranged alternately in the Y-axis direction. Specifically, the widths 41Wy of the multiple low refractive index sections 41 and 42Wy of the multiple high refractive index sections 42 arranged alternately in the Y-axis direction are narrower than the widths 41Wx of the multiple low refractive index sections 41 and 42Wx of the multiple high refractive index sections 42 arranged alternately in the X-axis direction, respectively, and the period in the Y-axis direction is shorter than the period in the X-axis direction. Near-infrared light L2 passing through the subwavelength lens 40C having such a configuration is focused in a horizontal shape. Therefore, reflection or absorption of near-infrared light L2 by the wiring layers (e.g., wiring layers 512, 532) mainly provided in the X-axis direction is reduced. 【0108】 Even with this configuration, the modified photodetector 1C can achieve the same effects as the embodiment described above. 【0109】 (2-4. Modification 4) Figure 22 schematically shows an example of the cross-sectional configuration of the photodetector (photodetector 1D) according to Modification 4 of the present disclosure. Figure 23 schematically shows the planar configuration of the subwavelength lens 40D along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1D shown in Figure 22. Note that Figure 22 represents a cross-section corresponding to the V-V' line shown in Figure 23. The photodetector 1D, like the photodetector 1 of the above embodiment, is applied to, for example, image sensors such as digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method. 【0110】 In the above embodiment and modification 1, an example was shown in which one second pixel P2 is stacked on top of four first pixels P1 arranged in a 2x2 grid, and zones Z1, Z2, and Z3 are provided in an annular shape from the center of the four first pixels P1 arranged in a 2x2 grid, which coincide with the center of the second pixel P2. However, the invention is not limited to this. The photodetector 1D in this modification includes, for example, a subwavelength lens 40D in which one second pixel P2 is stacked on top of one first pixel P1, and zones Z1, Z2, and Z3 are provided in an annular shape from the center of the first pixel P1 which coincides with the center of the second pixel P2. Except for this point, the photodetector 1D has substantially the same configuration as the photodetector 1 of the above embodiment. 【0111】 In this modified photodetector 1D, the beam of visible light L1 passes through zone Z1 of the subwavelength lens 40D. Furthermore, in this modified photodetector 1D, since the optical axis of the subwavelength lens 40D and the optical axis of the on-chip lens 44 are coaxial, the reflection or absorption of near-infrared light L2 by the above structures (e.g., the wiring layers 512, 532) is reduced by forming the floating diffusion FD1, the transfer transistor TR1, one or more wiring layers 512, 532, and multiple pad electrodes 513, 533 between adjacent first pixels P1. 【0112】Even with this configuration, the modified photodetector 1D can obtain the same effects as in the above embodiment. 【0113】 (2-5. Modification 5) Figure 24 schematically shows an example of the cross-sectional configuration of the photodetector (photodetector 1E) according to Modification 5 of the present disclosure. Figure 25 schematically shows the planar configuration of the subwavelength lens 40E along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1E shown in Figure 24. Note that Figure 24 represents a cross-section corresponding to the VI-VI' line shown in Figure 25. The photodetector 1E, like the photodetector 1 of the above embodiment, is applied to, for example, image sensors such as digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method. 【0114】 In the above embodiment, an example was shown in which the low refractive index portion 41 and the high refractive index portion 42 are alternately arranged in the XY plane direction in a subwavelength lens 40 in which the duty cycles of the low refractive index portion 41 and the high refractive index portion 42 are different for each annular zone Z1, Z2, Z3, but the invention is not limited to this. In this modified example, the photodetector 1E has the low refractive index portion 41 and the high refractive index portion 42 stacked in the optical axis direction (for example, the Z axis direction), and is equipped with a subwavelength lens 40E in which the duty cycles of the low refractive index portion 41 and the high refractive index portion 42 are different for each annular zone Z1, Z2, Z3, for example, by changing the thickness of the high refractive index portion 42. Except for this point, the photodetector 1E has substantially the same configuration as the photodetector 1 of the above embodiment. 【0115】The subwavelength lens 40E, like the subwavelength lens 40 of the above embodiment, has annular zones Z1, Z2, and Z3. In the subwavelength lens 40E, as described above, the low refractive index portion 41 and the high refractive index portion 42 are stacked in the optical axis direction (for example, the Z axis direction), and the thickness of the high refractive index portion 42 differs for each zone Z1, Z2, and Z3. Specifically, in the subwavelength lens 40E, the high refractive index portion 42 and the low refractive index portion 41 are stacked in this order from the semiconductor substrate 11 side, and the thickness of the high refractive index portion 42 is configured to increase in a stepped manner from zone Z3 to zone Z1. In other words, the duty cycle within each zone Z1, Z2, and Z3 is configured to be uniform, similar to the subwavelength lens 40, and the duty cycle between each zone Z1, Z2, and Z3 is configured to increase from the outer periphery of the second pixel P2 toward the optical axis of the subwavelength lens 40E, for example toward the center of the second pixel P2. Furthermore, in the subwavelength lens 40E, the widths of the stepped high refractive index sections 42, in other words, the widths of zones Z1, Z2, and Z3, are configured to be larger than the spot size L1s of the visible light L1 beam (for example, about 700 nm when the visible light L1 is red light) and smaller than the wavelength of near-infrared light L2 (for example, 1300 nm), so that the visible light L1 passes through, for example, zone Z2. As a result, the subwavelength lens 40E functions as a parallel plate for visible light L1 and as a phase difference lens for near-infrared light L2. 【0116】 Even with this configuration, the modified photodetector 1E can obtain the same effects as in the above embodiment. 【0117】 (2-6. Modification 6) Figure 26 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1F) according to Modification 6 of the present disclosure. The photodetector 1F is applied to, for example, an image sensor such as a digital still camera or video camera, or a distance image sensor that measures distance by the ToF method, similar to the photodetector 1 of the above embodiment. 【0118】In the above modified example 5, a subwavelength lens 40E is shown in which a low refractive index portion 41 and a high refractive index portion 42 are stacked in the optical axis direction (for example, the Z axis direction), and the duty cycles of the annularly arranged zones Z1, Z2, and Z3 are made different by, for example, changing the thickness of the high refractive index portion 42. However, the invention is not limited to this. In this modified example, the photodetector 1F is equipped with a subwavelength lens 40F in which the second surface 11S2 of the semiconductor substrate 11 is processed in a stepped shape and used as a substitute for the high refractive index portion 42. Except for this point, the photodetector 1F has substantially the same configuration as the photodetector 1 of the above embodiment. 【0119】 The step on the second surface 11S2 of the semiconductor substrate 11 constituting the subwavelength lens 40F can be formed by removing the semiconductor substrate 11, for example, by etching. 【0120】 Even with this configuration, the photodetector 1F of this modified example can obtain the same effects as in the above embodiment. 【0121】 Furthermore, in this modified example, the subwavelength lens 40F is composed of silicon nitride (Si) which constitutes the high refractive index portion 42 in the subwavelength lens 40, etc. ３ N ４ A Si substrate (semiconductor substrate 11) with a higher refractive index than ) was used as the high refractive index portion. As a result, the subwavelength lens 40F can obtain the same lens effect with a smaller step than, for example, the step of the high refractive index portion 42 of the subwavelength lens 40E in the modified example 5 described above. Therefore, for example, if the visible light L1 beam is blocked by the step of the high refractive index portion 42 of the subwavelength lens 40E, this can be improved by using the subwavelength lens 40F of this modified example. 【0122】 (2-7. Modification 7) Figure 27 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1G) according to Modification 7 of the present disclosure. The photodetector 1G is applied to, for example, an image sensor such as a digital still camera or video camera, or a distance image sensor that measures distance by the ToF method, similar to the photodetector 1 of the above embodiment. 【0123】In this modified optical detection device 1G, among zones Z1, Z2, and Z3, only zone Z1, which is closest to the optical axis, is detected, for example, silicon nitride (Si ３ N ４ A high refractive index section 42A is provided, and in zones Z2 and Z3, a subwavelength lens 40G is provided using a stepped semiconductor substrate 11 as the high refractive index section 42B. Except for this point, the photodetector 1G has substantially the same configuration as the photodetector 1 of the above embodiment. 【0124】 Even with this configuration, the photodetector 1G of this modified example can obtain the same effects as in the above embodiment. 【0125】 Furthermore, the subwavelength lens 40G of this modified example has a structure that is effective when certain semiconductor processing processes are reused with other processes, such as when processing the steps of the semiconductor substrate 11 in zones Z2 and Z3 in combination with so-called Shallow Trench Isolation (STI) processing. 【0126】 (2-8. Modification 8) Figure 28 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1H) according to Modification 8 of the present disclosure. Figure 29 schematically shows the planar configuration of the subwavelength lens 40H along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1H shown in Figure 28. Note that Figure 28 represents a cross-section corresponding to the line VII-VII' shown in Figure 29. The photodetector 1H, like the photodetector 1 of the above embodiment, is applied to, for example, image sensors such as digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method. 【0127】 This modified optical detection device 1H has two annular zones Z1 and Z2, and only in zone Z1, which is close to the optical axis, is silicon nitride (Si ３ N ４ A high refractive index section 42 is provided, and zone Z2 is equipped with a subwavelength lens 40H consisting only of a low refractive index section 41. Except for this point, the photodetector 1H has substantially the same configuration as the photodetector 1 of the above embodiment. 【0128】In this modified subwavelength lens 40H, there are two regions (zones Z1 and Z2) where the duty cycles of the low refractive index portion 41 and the high refractive index portion 42 are different. Although the lens effect is smaller compared to a subwavelength lens 40G etc. which has three regions (zones Z1, Z2, and Z3), it is easier to manufacture. 【0129】 Even with this configuration, the photodetector 1H of this modified example can obtain the same effects as in the above embodiment. 【0130】 (2-9. Modification 9) Figure 30 schematically shows an example of the cross-sectional configuration of the photodetector (photodetector 1I) according to Modification 9 of the present disclosure. Figure 31 schematically shows the planar configuration of the subwavelength lens 40I along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1I shown in Figure 30. Note that Figure 30 represents a cross-section corresponding to the line VIII-VIII' shown in Figure 31. The photodetector 1I is applied to image sensors such as those in digital still cameras and video cameras, and to distance image sensors that measure distance by the ToF method, similar to the photodetector 1 of the above embodiment. 【0131】 The modified photodetector 1I includes a subwavelength lens 40I having two zones Z1 and Z2 formed by processing the second surface 11S2 of the semiconductor substrate 11 in a stepped manner. Except for this point, the photodetector 1I has substantially the same configuration as the photodetector 1 of the above embodiment. 【0132】 The step on the second surface 11S2 of the semiconductor substrate 11 constituting the subwavelength lens 40I can be formed by etching the semiconductor substrate 11. Similar to the subwavelength lens 40H of the above modification 8, this modified subwavelength lens 40I has two regions (zones Z1 and Z2) with different duty cycles for the low refractive index portion 41 and the high refractive index portion 42. Although the lens effect is smaller compared to the subwavelength lens 40G etc. which has three regions (zones Z1, Z2, Z3), the processing steps can be reduced by using it in combination with, for example, STI processing. 【0133】Even with this configuration, the modified photodetector 1I can achieve the same effects as in the above embodiment. 【0134】 (2-10. Modification 10) Figure 32 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1J) according to Modification 10 of the present disclosure. The photodetector 1J, like the photodetector 1 of the above embodiment, is applied to, for example, image sensors such as those in digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method. 【0135】 The modified photodetector 1J further includes a subwavelength lens 54 having a configuration similar to that of the subwavelength lens 40 in the above embodiment, on the first surface 11S1 of the semiconductor substrate 11. The subwavelength lens 54 corresponds to one specific example of the "third optical member" as one embodiment of the present disclosure. Except for this point, the photodetector 1J has a substantially similar configuration to the photodetector 1 of the above embodiment. 【0136】 Thus, in this modified photodetector 1J, subwavelength lenses 40 and 54 are arranged on both sides of the first surface 11S1 and the second surface 11S2 of the semiconductor substrate 11. As shown in Figure 32, for example, the focusing characteristics of near-infrared light L2 onto the photoelectric conversion unit 22 embedded in the semiconductor substrate 21 can be improved. Therefore, this modified photodetector 1J can further improve quantum efficiency compared to the photodetector 1 of the above embodiment. 【0137】 (2-11. Modification 11) Figure 33 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1K) according to Modification 11 of the present disclosure. Figure 34 schematically shows the planar configuration of the subwavelength lens 40J along with the planar layout of the first pixel P1 and the second pixel P2 of the photodetector 1I shown in Figure 33. Note that Figure 33 represents a cross-section corresponding to the IX-IX' line shown in Figure 34. The photodetector 1K, like the photodetector 1 of the above embodiment, is applied to, for example, image sensors such as digital still cameras and video cameras, and distance image sensors that measure distance by the ToF method. 【0138】In the above embodiment, an example was shown in which the low refractive index portion 41 and the high refractive index portion 42 are alternately arranged in the XY plane in a subwavelength lens 40 in which the duty cycles of the low refractive index portion 41 and the high refractive index portion 42 are different for each annular zone Z1, Z2, Z3, but the invention is not limited to this. In this modified example, the photodetector 1K is equipped with a subwavelength lens 40E having annular zones Z1, Z2, Z3 in which the duty cycles of the low refractive index portion 41 and the high refractive index portion 42 are different for each zone Z1, Z2, Z3, by arranging a plurality of high refractive index portions 42A having a columnar structure at a predetermined period for each zone Z1, Z2, Z3. Except for this point, the photodetector 1K has substantially the same configuration as the photodetector 1 of the above embodiment. 【0139】 As described above, the subwavelength lens 40J has a plurality of high refractive index sections 42 having a columnar structure arranged at a predetermined period. The plurality of high refractive index sections 42 are pillars having a circular or polygonal planar shape, and, similar to the subwavelength lens 40, are arranged at a constant period for each zone Z1, Z2, Z3 such that the duty cycle between each zone Z1, Z2, Z3 increases from the outer periphery of the second pixel P2 toward the optical axis of the subwavelength lens 40J, for example, toward the center of the second pixel P2. 【0140】 Even with this configuration, the photodetector 1K of this modified example can obtain the same effects as in the above embodiment. 【0141】 Furthermore, in the modified subwavelength lens 40J, a plurality of high refractive index sections 42 having a columnar structure are arranged at predetermined intervals for each zone Z1, Z2, and Z3, thereby forming zones Z1, Z2, and Z3 in which the duty cycles of the low refractive index section 41 and the high refractive index section 42 are different from each other. As a result, the shapes of zones Z1, Z2, and Z3 can be freely designed compared to the subwavelength lenses of the above embodiment and modified examples 1 to 9 (for example, subwavelength lens 40). For example, it is possible to accommodate complex shapes such as forming zone Z2 while avoiding the pixel separation section 13. 【0142】(2-12. Modification 12) Figure 35 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1L) according to Modification 11 of the present disclosure. The photodetector 1L is applied to, for example, an image sensor such as a digital still camera or video camera, or a distance image sensor that measures distance by the ToF method, similar to the photodetector 1 of the above embodiment. 【0143】 In the above embodiment, an example was shown in which a subwavelength lens 40 is provided on the second surface 11S2 of the semiconductor substrate 11 and a color filter 43 is provided on the subwavelength lens 40, but the invention is not limited to this. In this modified example, the photodetector 1L has a color filter 43 provided on the second surface 11S2 of the semiconductor substrate 11, and a subwavelength lens 40K is arranged on the color filter 43 via a planarizer 45. Except for this point, the photodetector 1L has substantially the same configuration as the photodetector 1 of the above embodiment. 【0144】 Even with this configuration, the photodetector 1L of this modified example can obtain the same effects as in the above embodiment. 【0145】 <3. Application Examples> (Application Example 1) The light detection device according to the above embodiment and modified examples 1 to 11 (for example, light detection device 1) can be applied to various electronic devices such as imaging systems such as digital still cameras and digital video cameras, mobile phones equipped with imaging functions, or other devices equipped with imaging functions. 【0146】 Figure 36 is a block diagram showing an example of the configuration of the electronic device 1000. 【0147】 As shown in Figure 36, the electronic device 1000 includes an optical system 1001, a light detection device 1, and a DSP (Digital Signal Processor) 1002. The DSP 1002, memory 1003, display device 1004, recording device 1005, operating system 1006, and power supply system 1007 are connected via a bus 1008, and it is capable of capturing still and moving images. 【0148】The optical system 1001 is composed of one or more lenses and captures incident light (image light) from the subject and forms an image on the imaging surface of the light detection device 1. 【0149】 The light detection device 1 converts the amount of incident light imaged onto the imaging surface by the optical system 1001 into an electrical signal on a pixel-by-pixel basis and supplies it to the DSP 1002 as a pixel signal. 【0150】 The DSP 1002 performs various signal processing on the signal from the light detection device 1 to acquire an image, and temporarily stores the image data in the memory 1003. The image data stored in the memory 1003 is recorded in the recording device 1005 or supplied to the display device 1004 to display the image. The operation system 1006 accepts various operations from the user and supplies operation signals to each block of the electronic device 1000, and the power supply system 1007 supplies the power necessary to drive each block of the electronic device 1000. 【0151】 (Application Example 2) Figure 37A schematically shows an example of the overall configuration of a photodetection system 2000 equipped with a photodetector 1. Figure 37B shows an example of the circuit configuration of the photodetection system 2000. The photodetection system 2000 includes a light-emitting device 2001 as a light source unit that emits infrared and near-infrared light L2, and a photodetector 2002 as a light-receiving unit that has a photoelectric conversion element. The photodetector 1 described above can be used as the photodetector 2002. The photodetection system 2000 may further include a system control unit 2003, a light source drive unit 2004, a sensor control unit 2005, a light source side optical system 2006, and a camera side optical system 2007. 【0152】The photodetector 2002 can detect visible light L1 and near-infrared light L2. Visible light L1 is light reflected from ambient light from the outside by the subject (object to be measured) 2100 (Figure 37A). Near-infrared light L2 is light that has been emitted by the light-emitting device 2001 and then reflected by the subject 2100. Visible light L1 is, for example, visible light, and near-infrared light L2 is, for example, infrared light. Visible light L1 is detectable in the photoelectric conversion unit of the photodetector 2002, and near-infrared light L2 is detectable in the photoelectric conversion region of the photodetector 2002. Image information of the subject 2100 can be obtained from the visible light L1, and distance information between the subject 2100 and the photodetector system 2000 can be obtained from the near-infrared light L2. The photodetector system 2000 can be mounted on, for example, electronic devices such as smartphones or mobile devices such as cars. The light-emitting device 2001 can be composed of, for example, a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). As a detection method for the near-infrared light L2 emitted from the light-emitting device 2001 by the photodetector 2002, for example, the iTOF method can be employed, but is not limited to this. In the iTOF method, the photoelectric conversion unit can measure the distance to the object 2100 by, for example, the time-of-flight (TOF). As a detection method for the near-infrared light L2 emitted from the light-emitting device 2001 by the photodetector 2002, for example, the structured light method or the stereo vision method can also be employed. For example, in the structured light method, a predetermined pattern of light is projected onto the object 2100, and the distance between the photodetector 2000 and the object 2100 can be measured by analyzing the degree of distortion of the pattern. Furthermore, in the stereo vision system, for example, by using two or more cameras to acquire two or more images of the subject 2100 from two or more different viewpoints, the distance between the light detection system 2000 and the subject can be measured. The light-emitting device 2001 and the light detection device 2002 can be synchronously controlled by the system control unit 2003. 【0153】(Application Example 3) Figure 38 shows an example of a schematic configuration of a distance imaging device 3000 equipped with a light detection device (for example, light detection device 1) according to the first and second embodiments and modified examples 1 and 2 described above. 【0154】 The distance imaging device 3000 includes, for example, a light source device 3100, an optical system 3200, a light detection device 1, an image processing circuit 3300, a monitor 3400, and a memory 3500. 【0155】 The distance imaging device 3000 receives light (modulated light or pulsed light) that is projected from the light source device 3100 toward the object to be illuminated 4000 and reflected from the surface of the object to be illuminated 4000, thereby acquiring a distance image corresponding to the distance to the object to be illuminated 4000. 【0156】 The optical system 3200 is composed of one or more lenses and guides the image light (incident light) from the object to be illuminated 4000 to the light detection device 1, and forms an image on the light-receiving surface (sensor part) of the light detection device 1. 【0157】 The image processing circuit 3300 performs image processing to construct a distance image based on the distance signal supplied from the light detection device 1. The distance image (image data) obtained through this image processing is supplied to the monitor 3400 for display or supplied to the memory 3500 for storage (recording). 【0158】 In the distance imaging device 3000 configured in this way, by applying the above-described light detection device (for example, light detection device 1), it becomes possible to calculate the distance to the illuminated object 4000 based only on the light received signal from the highly stable unit pixel P, and to generate a highly accurate distance image. In other words, the distance imaging device 3000 can acquire a more accurate distance image. 【0159】 <4. Application Examples> (Application Example to Endoscopic Surgical Systems) The technology disclosed herein (this technology) can be applied to various products. For example, the technology disclosed herein may be applied to an endoscopic surgical system. 【0160】 Figure 39 is a diagram showing an example of a schematic configuration of an endoscopic surgical system to which the technology described herein (the technology) may be applied. 【0161】 Figure 39 illustrates a surgeon (physician) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgical system 11000. As shown in the figure, the endoscopic surgical system 11000 consists of an endoscope 11100, other surgical instruments 11110 such as an insufflation tube 11111 and an energy treatment device 11112, a support arm device 11120 for supporting the endoscope 11100, and a cart 11200 equipped with various devices for endoscopic surgery. 【0162】 The endoscope 11100 consists of a barrel 11101, the tip of which is inserted into the body cavity of the patient 11132 for a predetermined length, and a camera head 11102 connected to the base end of the barrel 11101. In the illustrated example, the endoscope 11100 is shown as a so-called rigid endoscope having a rigid barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible endoscope having a flexible barrel. 【0163】 An opening into which an objective lens is fitted is provided at the tip of the microscope tube 11101. A light source device 11203 is connected to the endoscope 11100, and the light generated by the light source device 11203 is guided to the tip of the microscope tube by a light guide extending inside the microscope tube 11101, and is irradiated through the objective lens towards the object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a straight-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope. 【0164】 The camera head 11102 contains an optical system and an image sensor. Reflected light from the object being observed (observation light) is focused onto the image sensor by the optical system. The image sensor converts the observation light into electrical signals, generating an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. This image signal is transmitted as RAW data to the camera control unit (CCU) 11201. 【0165】The CCU 11201 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and other components, and comprehensively controls the operation of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102 and performs various image processing operations on that image signal, such as development processing (demosaic processing), to display an image based on that image signal. 【0166】 The display device 11202 displays an image based on an image signal that has been processed by the CCU 11201, under control from the CCU 11201. 【0167】 The light source device 11203 is composed of a light source such as an LED (light-emitting diode) and supplies illumination light to the endoscope 11100 when photographing the surgical area, etc. 【0168】 The input device 11204 is an input interface for the endoscopic surgical system 11000. The user can input various types of information and instructions to the endoscopic surgical system 11000 via the input device 11204. For example, the user can input instructions to change the imaging conditions (type of light, magnification, focal length, etc.) of the endoscope 11100. 【0169】 The treatment instrument control device 11205 controls the drive of the energy treatment instrument 11112 for purposes such as tissue cauterization, incision, or blood vessel sealing. The insufflation device 11206 injects gas into the body cavity of the patient 11132 via the insufflation tube 11111 to inflate the body cavity for the purpose of securing a field of view by the endoscope 11100 and securing the operator's workspace. The recorder 11207 is a device capable of recording various information related to the surgery. The printer 11208 is a device capable of printing various information related to the surgery in various formats such as text, images, or graphs. 【0170】The light source device 11203 that supplies illumination light to the endoscope 11100 when photographing the surgical area can be configured as a white light source consisting of, for example, an LED, a laser light source, or a combination thereof. When the white light source is configured as a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so the white balance of the captured image can be adjusted in the light source device 11203. In this case, it is also possible to capture images corresponding to each of the RGB colors in time-division by irradiating the observation target with laser light from each of the RGB laser light sources in time-division and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter on the image sensor. 【0171】 Furthermore, the light source device 11203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. By controlling the drive of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity, images can be acquired in time-division order, and these images can be combined to generate high dynamic range images without so-called black crushing and white clipping. 【0172】Furthermore, the light source device 11203 may be configured to supply light in a predetermined wavelength range corresponding to special light observation. In special light observation, for example, so-called narrow-band imaging is performed, in which a predetermined tissue such as blood vessels on the surface of the mucosa is imaged with high contrast by irradiating with narrow-band light compared to the irradiation light used in normal observation (i.e., white light), utilizing the wavelength dependence of light absorption in body tissue. Alternatively, fluorescence observation may be performed in special light observation, in which an image is obtained from fluorescence generated by irradiation with excitation light. In fluorescence observation, fluorescence can be obtained by irradiating body tissue with excitation light and observing the fluorescence from the body tissue (autofluorescence observation), or by locally injecting a reagent such as indocyanine green (ICG) into body tissue and irradiating the body tissue with excitation light corresponding to the fluorescence wavelength of the reagent to obtain a fluorescence image. The light source device 11203 may be configured to supply narrow-band light and / or excitation light corresponding to such special light observation. 【0173】 Figure 40 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in Figure 39. 【0174】 The camera head 11102 includes a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other via a transmission cable 11400 so that they can communicate with each other. 【0175】 The lens unit 11401 is an optical system provided at the connection point with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and then incident on the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses, including a zoom lens and a focus lens. 【0176】The imaging unit 11402 may consist of one image sensor (a so-called single-chip type) or multiple image sensors (a so-called multi-chip type). If the imaging unit 11402 is configured as a multi-chip type, for example, each image sensor may generate image signals corresponding to RGB, and these may be combined to obtain a color image. Alternatively, the imaging unit 11402 may be configured to have a pair of image sensors for acquiring image signals for the right eye and left eye, respectively, corresponding to 3D (dimensional) display. By performing 3D display, the surgeon 11131 can more accurately grasp the depth of the biological tissue in the surgical area. In addition, if the imaging unit 11402 is configured as a multi-chip type, multiple lens units 11401 may be provided corresponding to each image sensor. 【0177】 Furthermore, the imaging unit 11402 does not necessarily have to be located on the camera head 11102. For example, the imaging unit 11402 may be located inside the lens barrel 11101, directly behind the objective lens. 【0178】 The drive unit 11403 is composed of actuators and, under control from the camera head control unit 11405, moves the zoom lens and focus lens of the lens unit 11401 along the optical axis by a predetermined distance. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted as appropriate. 【0179】 The communication unit 11404 is composed of communication devices for sending and receiving various types of information with the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 as RAW data to the CCU 11201 via the transmission cable 11400. 【0180】 Furthermore, the communication unit 11404 receives a control signal from the CCU 11201 to control the drive of the camera head 11102 and supplies it to the camera head control unit 11405. The control signal includes information about imaging conditions, such as information to specify the frame rate of the captured image, information to specify the exposure value at the time of imaging, and / or information to specify the magnification and focus of the captured image. 【0181】The imaging conditions such as frame rate, exposure value, magnification, and focus may be specified by the user as appropriate, or they may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with so-called AE (Auto Exposure), AF (Auto Focus), and AWB (Auto White Balance) functions. 【0182】 The camera head control unit 11405 controls the driving of the camera head 11102 based on the control signal received from the CCU 11201 via the communication unit 11404. 【0183】 The communication unit 11411 is comprised of a communication device for sending and receiving various types of information with the camera head 11102. The communication unit 11411 receives image signals transmitted from the camera head 11102 via the transmission cable 11400. 【0184】 Furthermore, the communication unit 11411 transmits control signals to the camera head 11102 to control the driving of the camera head 11102. Image signals and control signals can be transmitted by telecommunications, optical communications, etc. The image processing unit 11412 performs various image processing on the image signal, which is RAW data transmitted from the camera head 11102. 【0185】 The control unit 11413 performs various controls related to imaging the surgical area, etc., by the endoscope 11100, and the display of the images obtained from imaging the surgical area, etc. For example, the control unit 11413 generates a control signal to control the driving of the camera head 11102. 【0186】Furthermore, the control unit 11413 displays the captured image showing the surgical area, etc., on the display device 11202 based on the image signal processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical instruments such as forceps, specific biological sites, bleeding, mist when using the energy treatment device 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When the control unit 11413 displays the captured image on the display device 11202, it may use the recognition results to superimpose various surgical support information onto the image of the surgical area. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced, and the surgeon 11131 can proceed with the surgery reliably. 【0187】 The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable compatible with electrical signal communication, an optical fiber compatible with optical communication, or a composite cable thereof. 【0188】 In the illustrated example, communication was performed via a wired connection using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may be performed wirelessly. 【0189】 The above describes an example of an endoscopic surgical system to which the technology described herein may be applied. The technology described herein can be applied to the imaging unit 11402 of the configuration described above. By applying the technology described herein to the imaging unit 11402, the detection accuracy is improved. 【0190】 While an endoscopic surgical system has been described here as an example, the technology described herein may also be applied to other systems, such as microsurgical systems. 【0191】(Examples of application to mobile devices) The technology disclosed herein can be applied to a variety of products. For example, the technology disclosed herein may be implemented as a device mounted on any type of mobile device, such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, robots, construction machinery, or agricultural machinery (tractors). 【0192】 Figure 41 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied. 【0193】 The vehicle control system 12000 comprises a plurality of electronic control units connected via a communication network 12001. In the example shown in Figure 41, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 is shown in the figure, which includes a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053. 【0194】 The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle. 【0195】The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc. 【0196】 The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the external information detection unit 12030. The external information detection unit 12030 causes the imaging unit 12031 to capture images of the outside of the vehicle and receives the captured images. Based on the received images, the external information detection unit 12030 may perform object detection processing such as detecting people, cars, obstacles, signs, or characters on the road surface, or distance detection processing. 【0197】 The imaging unit 12031 is a light sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light. 【0198】 The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that captures images of the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041. 【0199】The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on information inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning. 【0200】 Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040. 【0201】 Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams. 【0202】 The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 41, the output devices include an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display. 【0203】 Figure 42 shows an example of the installation position of the imaging unit 12031. 【0204】In Figure 42, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105. 【0205】 The imaging units 12101, 12102, 12103, 12104, and 12105 are installed, for example, on the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle 12100. The imaging unit 12101 installed on the front nose and the imaging unit 12105 installed on the upper part of the windshield inside the vehicle mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 installed on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 installed on the upper part of the windshield inside the vehicle is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes. 【0206】 Figure 42 shows an example of the imaging ranges of imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of imaging unit 12101 located on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of imaging units 12102 and 12103 located on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of imaging unit 12104 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 12101 to 12104, an overhead view image of the vehicle 12100 can be obtained. 【0207】 At least one of the imaging units 12101 to 12104 may have a function for acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple image sensors, or an image sensor having pixels for phase difference detection. 【0208】For example, the microcomputer 12051, based on distance information obtained from the imaging units 12101 to 12104, can determine the distance to each object within the imaging range 12111 to 12114 and the temporal change of this distance (relative speed to the vehicle 12100). In particular, it can extract the closest object on the vehicle 12100's path that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or more) as the preceding vehicle. Furthermore, the microcomputer 12051 can set a predetermined distance to be maintained before the preceding vehicle and perform automatic braking control (including follow-and-stop control) and automatic acceleration control (including follow-and-start control), etc. In this way, cooperative control aimed at autonomous driving, etc., that drives autonomously without driver operation, can be performed. 【0209】 For example, the microcomputer 12051 can use distance information obtained from imaging units 12101 to 12104 to classify and extract three-dimensional object data related to three-dimensional objects, such as motorcycles, passenger cars, large vehicles, pedestrians, utility poles, and other three-dimensional objects, and use this data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle. If the collision risk is above a set value and there is a possibility of collision, the microcomputer 12051 can provide driving assistance to avoid collisions by outputting a warning to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010. 【0210】At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared light. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not pedestrians are present in the images captured by the imaging units 12101 to 12104. Such pedestrian recognition is performed, for example, by a procedure to extract feature points from the images captured by the imaging units 12101 to 12104 as infrared cameras, and a procedure to perform pattern matching on a series of feature points that indicate the contour of an object to determine whether or not it is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the imaging units 12101 to 12104 and recognizes a pedestrian, the audio-image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio-image output unit 12052 may also control the display unit 12062 to display an icon indicating a pedestrian at a desired position. 【0211】 The above describes an example of a mobile object control system to which the technology of this disclosure may be applied. The technology of this disclosure can be applied to the imaging unit 12031 of the configuration described above. Specifically, the light detection device (for example, light detection device 1) according to the above embodiment and its modified examples 1 to 12 can be applied to the imaging unit 12031. By applying the technology of this disclosure to the imaging unit 12031, high-definition captured images with low noise can be obtained, so that high-precision control using captured images can be performed in the mobile object control system. 【0212】 Although the embodiments and modifications 1 to 12 described above, as well as application examples and usage examples, the contents of this disclosure are not limited to the embodiments described above, and various modifications are possible. 【0213】For example, in the above embodiments, an example was shown in which the photoelectric conversion unit 22 that detects light in the near-infrared region is composed of a photodiode, but it is not limited to this. The second pixel P2 that detects light in the near-infrared region may be configured as, for example, a SPAD pixel. By applying this technology to a light detection device in which the second pixel P2 that detects light in the near-infrared region is configured as a SPAD pixel, the light in the near-infrared region is focused to the center of the second pixel P2, so that the charge transfer path to the multiplication unit provided in the center of the pixel is shortened. Therefore, it becomes possible to suppress signal delay. 【0214】 Furthermore, in the above embodiments, an example was shown in which, in each zone Z1, Z2, and Z3 where the ratio of the low refractive index portion 41 to the high refractive index portion 42 differs from one another, the ratio of the high refractive index portion 42 increases from the outer periphery to the center of the second pixel P2. A subwavelength lens 40 having such a configuration functions as a convex lens, but is not limited to this. The subwavelength lens 40 may also be configured such that, in each zone Z1, Z2, and Z3 where the ratio of the low refractive index portion 41 to the high refractive index portion 42 differs from one another, the ratio of the high refractive index portion 42 decreases from the outer periphery to the center of the second pixel P2. A subwavelength lens 40 configured in this way functions as a concave lens. 【0215】 Furthermore, the photodetector in this disclosure does not need to include all of the components described in the above embodiments, and conversely, it may also include other layers. 【0216】 Furthermore, the polarity of the semiconductor region constituting the photodetector of the present disclosure may be reversed. Furthermore, the photodetector of the present disclosure may use holes as signal charges. 【0217】 Furthermore, the shape of the unit pixel P is not limited to a rectangular shape. For example, the unit pixel P may be octagonal, and the multiple unit pixels P constituting the pixel array 100 may be arranged in a honeycomb pattern. 【0218】 The effects described in the above embodiments are merely examples, and other effects may also be present, or even further effects may be included. 【0219】The present disclosure may also have the following configuration. According to the present technology with the following configuration, in a photodetector in which a first semiconductor substrate and a second semiconductor substrate are stacked, a first optical member is provided on the side of the first semiconductor substrate that is the light incident surface opposite to the surface on which the second semiconductor substrate is stacked. The first semiconductor substrate has a plurality of first pixels for detecting light in the first wavelength range arranged in a two-dimensional array, and the second semiconductor substrate has a plurality of second pixels for detecting light in the second wavelength range, which has a longer wavelength than the first wavelength range, arranged in a two-dimensional array. The first optical member includes a first refractive index portion and a second refractive index portion with a lower refractive index than the first refractive index portion, and has a plurality of annular regions extending from the center of the second pixel. The plurality of regions are configured such that the ratio of the first refractive index portion to the second refractive index portion differs from one another, and the ratio of the first refractive index portion increases from the outer periphery of the second pixel towards the center. As a result, it is possible to concentrate light in a predetermined wavelength range (light in the second wavelength range) from the light incident on the photodetector to the center of the second pixel, thereby improving quantum efficiency. (1) A light detection device comprising: a first semiconductor substrate having a first surface and a second surface, on which a plurality of first pixels for detecting light in a first wavelength range are arranged in a two-dimensional array, and which have opposing first surfaces and second surfaces; a second semiconductor substrate disposed on the first surface side of the first semiconductor substrate, on which a plurality of second pixels for detecting light in a second wavelength range with a longer wavelength than the first wavelength range are arranged in a two-dimensional array; and a first optical member disposed on the second surface side of the first semiconductor substrate, which includes a first refractive index portion and a second refractive index portion with a lower refractive index than the first refractive index portion, and has a plurality of annular regions extending from the center of the second pixel, the plurality of regions having different ratios of the first refractive index portion and the second refractive index portion, and the ratio of the first refractive index portion increasing from the outer periphery to the center of the second pixel.(2) The light detection device according to (1), further comprising a second optical member positioned on the second surface side of the first semiconductor substrate between the first optical member and the first optical member, the second optical member focusing light in the first wavelength range onto each of the plurality of first pixels, wherein the width of the region among the plurality of regions that intersects with the optical axis of the second optical member is greater than the wavelength of the light in the first wavelength range focused by the second optical member and incident on the first optical member, and smaller than the spot diameter of the light in the second wavelength range focused by the second optical member and incident on the first optical member. (3) The light detection device according to (1) or (2), wherein the first refractive index portion and the second refractive index portion are alternately arranged in an annular shape in the direction lateral to the optical axis of the first optical member. (4) The light detection device according to (3), wherein the first refractive index portion has the same width for each of the plurality of regions. (5) The photodetector according to (4), wherein the first optical member has a plurality of regions, a first region, a second region and a third region, from the center of the second pixel, and the width of the first refractive index portion widens from the third region to the first region. (6) The photodetector according to any one of (3) to (5), wherein the periodic pattern of the alternately arranged first refractive index portions and second refractive index portions is substantially circular or substantially square. (7) The photodetector according to any one of (1) to (6), wherein four first pixels arranged in a 2x2 configuration are stacked for one second pixel, and the plurality of regions are provided in an annular shape from the center of the four first pixels arranged in a 2x2 configuration. (8) The light detection device according to any one of (1) to (7), wherein nine first pixels arranged in a 3x3 grid are stacked on one second pixel, and the first optical member has the plurality of regions provided in an annular shape from the center of the nine first pixels arranged in a 3x3 grid. (9) The light detection device according to any one of (1) to (8), wherein two first pixels arranged in a 1x2 grid are stacked on one second pixel, and the first optical member has the plurality of regions provided in an annular shape from the center of the two first pixels arranged in a 1x2 grid.(10) The optical detection device according to (9), wherein each of the plurality of regions has a width in the row direction and a width in the column direction that differs from one another. (11) The optical detection device according to (10), wherein the first refractive index portion and the second refractive index portion are alternately arranged in the direction lateral to the optical axis of the first optical member, and the arrangement period of the first refractive index portion and the second refractive index portion differs from one another in the row direction and the column direction. (12) The optical detection device according to any one of (1) to (11), wherein one first pixel is stacked for one second pixel, and the first optical member has the plurality of regions provided in an annular shape from the center of one first pixel. (13) The optical detection device according to any one of (1) to (12), wherein the first refractive index portion has a columnar structure, and the first optical member has a plurality of first refractive index portions arranged at a predetermined period for each of the plurality of regions. (14) The photodetector according to any one of (1) to (13), wherein the first refractive index portion and the second refractive index portion are stacked in this order in the optical axis direction of the first optical member. (15) The photodetector according to (14), wherein the first refractive index portion has the same thickness for each of the plurality of regions. (16) The photodetector according to (15), wherein the first optical member has a first region, a second region and a third region from the center of the second pixel as the plurality of regions, and the thickness of the first refractive index portion increases in a stepped manner from the third region to the first region. (17) The photodetector according to any one of (14) to (16), wherein the first refractive index portion is formed by the first semiconductor substrate. (18) The photodetector according to (17), wherein the plurality of regions are formed by steps formed on the second surface of the first semiconductor substrate. (19) The photodetector according to any one of (14) to (18), wherein, among the plurality of regions, the first refractive index portion of the central region is formed by containing silicon nitride, and the first refractive index portions of the regions other than the central region are formed by a first semiconductor substrate.(20) The photodetector according to any one of (1) to (19), further comprising a third optical member between the first semiconductor substrate and the second semiconductor substrate, wherein the third optical member includes a third refractive index portion and a fourth refractive index portion having a lower refractive index than the third refractive index portion, and has a plurality of annular regions extending from the center of the second pixel, the ratio of the third refractive index portion to the fourth refractive index portion differs for each of the plurality of regions, and the ratio of the third refractive index portion increases from the outer periphery of the second pixel towards the center. (21) The photodetector according to any one of (1) to (20), further comprising a plurality of floating diffusion layers for temporarily accumulating signal charges generated in each of the plurality of first pixels by photoelectric conversion, and a plurality of transfer transistors for transferring the signal charges generated in each of the plurality of first pixels to the plurality of floating diffusion layers, wherein the plurality of floating diffusion layers and the plurality of transfer transistors are each arranged in the outermost region of the plurality of regions on the first surface of the first semiconductor substrate in a plan view. (22) The light detection device according to any one of (1) to (21), further comprising a pixel array portion in which the plurality of first pixels and the plurality of second pixels are arranged in a two-dimensional array, wherein the centers of the annular first refractive index portion and the second refractive index portion of the first optical member provided on each of the plurality of second pixels are eccentric toward the center of the pixel array portion as they move away from the center of the pixel array portion. (23) The light detection device according to any one of (2) to (22), further comprising a color filter that selectively transmits light in a predetermined wavelength range from light in a first wavelength range, wherein the color filter is arranged on the second surface side of the first semiconductor substrate, and the first optical member is arranged between the second optical member and the color filter. 【0220】 This application claims priority based on Japanese Patent Application No. 2024-215522, filed with the Japan Patent Office on 10 December 2024, and all contents of that application are incorporated herein by reference. 【0221】Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. A light detection device comprising: a first semiconductor substrate having a first surface and a second surface, on which a plurality of first pixels for detecting light in a first wavelength range are arranged in a two-dimensional array, and which have opposing first surfaces and second surfaces; a second semiconductor substrate disposed on the first surface side of the first semiconductor substrate, on which a plurality of second pixels for detecting light in a second wavelength range with a longer wavelength than the first wavelength range are arranged in a two-dimensional array; and a first optical member disposed on the second surface side of the first semiconductor substrate, which includes a first refractive index portion and a second refractive index portion with a lower refractive index than the first refractive index portion, and has a plurality of annular regions extending from the center of the second pixel, the plurality of regions having different ratios of the first refractive index portion and the second refractive index portion, and the ratio of the first refractive index portion increasing from the outer periphery to the center of the second pixel.

2. The photodetector according to claim 1, further comprising a second optical member disposed on the second surface side of the first semiconductor substrate between the first optical member and the first optical member, the second optical member focusing light in the first wavelength range onto each of the plurality of first pixels, wherein the width of the region among the plurality of regions that intersects with the optical axis of the second optical member is greater than the wavelength of the light in the first wavelength range focused by the second optical member and incident on the first optical member, and smaller than the spot diameter of the light in the second wavelength range focused by the second optical member and incident on the first optical member.

3. The light detection device according to claim 1, wherein the first refractive index portion and the second refractive index portion are alternately arranged in an annular shape in the direction lateral to the optical axis of the first optical member.

4. The photodetector according to claim 3, wherein the first refractive index portion has the same width for each of the plurality of regions.

5. The photodetector according to claim 4, wherein the first optical member has a plurality of regions, a first region, a second region and a third region from the center of the second pixel, and the width of the first refractive index portion widens from the third region to the first region.

6. The photodetector according to claim 3, wherein the periodic pattern of the alternately arranged first refractive index portions and second refractive index portions is substantially circular or substantially square in shape.

7. The light detection device according to claim 1, wherein four first pixels arranged in a 2x2 configuration are stacked on one second pixel, and the first optical member has the plurality of regions provided in an annular shape from the center of the four first pixels arranged in a 2x2 configuration.

8. The light detection device according to claim 1, wherein nine first pixels arranged in a 3x3 grid are stacked on one second pixel, and the first optical member has the plurality of regions provided in an annular shape from the center of the nine first pixels arranged in a 3x3 grid.

9. The light detection device according to claim 1, wherein two first pixels arranged in a 1x2 configuration are stacked on one second pixel, and the first optical member has the plurality of regions provided in an annular shape from the center of the two first pixels arranged in a 1x2 configuration.

10. The photodetector according to claim 9, wherein each of the plurality of regions has a width in the row direction and a width in the column direction that differs from one another.

11. The light detection device according to claim 10, wherein the first refractive index portion and the second refractive index portion are alternately arranged in a direction laterally to the optical axis of the first optical member, and the arrangement periods of the first refractive index portion and the second refractive index portion are different from each other in the row direction and the column direction.

12. The light detection device according to claim 1, wherein one first pixel is stacked on one second pixel, and the first optical member has the plurality of regions provided in an annular shape from the center of one first pixel.

13. The photodetector according to claim 1, wherein the first refractive index portion has a columnar structure, and the first optical member has a plurality of first refractive index portions arranged at a predetermined period for each of the plurality of regions.

14. The photodetector according to claim 1, wherein the first refractive index portion and the second refractive index portion are stacked in this order in the direction of the optical axis of the first optical member.

15. The photodetector according to claim 14, wherein the first refractive index portion has the same thickness for each of the plurality of regions.

16. The photodetector according to claim 15, wherein the first optical member has a plurality of regions, a first region, a second region and a third region from the center of the second pixel, and the thickness of the first refractive index portion increases in a stepped manner from the third region to the first region.

17. The photodetector according to claim 14, wherein the first refractive index portion is formed by the first semiconductor substrate.

18. The photodetector according to claim 17, wherein the plurality of regions are formed by steps formed on the second surface of the first semiconductor substrate.

19. The photodetector according to claim 1, further comprising a third optical member between the first semiconductor substrate and the second semiconductor substrate, wherein the third optical member includes a third refractive index portion and a fourth refractive index portion having a lower refractive index than the third refractive index portion, and has a plurality of annular regions extending from the center of the second pixel, the ratio of the third refractive index portion to the fourth refractive index portion differs in each of the plurality of regions, and the ratio of the third refractive index portion increases from the outer periphery of the second pixel towards the center.

20. The photodetector according to claim 1, further comprising a plurality of floating diffusion layers for temporarily storing the signal charge generated in each of the plurality of first pixels by photoelectric conversion, and a plurality of transfer transistors for transferring the signal charge generated in each of the plurality of first pixels to the plurality of floating diffusion layers, wherein the plurality of floating diffusion layers and the plurality of transfer transistors are each arranged in the outermost region of the plurality of regions on the first surface of the first semiconductor substrate in a plan view.

Images