Photodetector and electronic equipment

Abstract

To provide an optical detection device and electronic equipment capable of achieving pixel miniaturization. [Solution] An optical detection device according to one embodiment of the present disclosure comprises a semiconductor substrate having a first surface which is an incident light surface and a second surface opposite to the first surface, with a photoelectric conversion unit embedded in each pixel; a first waveguide embedded in the semiconductor substrate and extending from the first surface to the second surface; and a light-collecting member disposed on the first surface side of the semiconductor substrate and guiding incident light to the first waveguide.

Description

[Technical Field]

[0001] This disclosure relates to a photodetector having a wavelength separation structure and an electronic device equipped therewith. [Background technology]

[0002] For example, Patent Document 1 discloses a photodetector in which an optical control region is stacked on the light incident side of a photoelectric conversion region having multiple pixels to control the direction of light propagation to the photoelectric conversion region. The optical control region has a pixel control region having a substructure for each of the multiple pixels, and the pixel control region controls the direction of light propagation of the amount of light within the aperture range corresponding to the image height. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2023 / 195392 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] By the way, miniaturization of pixels is required in light detection devices.

[0005] It is desirable to provide an optical detection device capable of achieving pixel miniaturization and an electronic device equipped therewith. [Means for solving the problem]

[0006] An optical detection device as one embodiment of the present disclosure comprises a semiconductor substrate having a first surface which is an incident light surface and a second surface opposite to the first surface, with a photoelectric conversion unit embedded in each pixel; a first waveguide embedded in the semiconductor substrate and extending from the first surface to the second surface; and a light-gathering member disposed on the first surface side of the semiconductor substrate and guiding incident light to the first waveguide.

[0007] An electronic device according to an embodiment of the present disclosure includes the photodetection device of the above embodiment of the present disclosure.

[0008] In the photodetection device and the electronic device according to an embodiment of the present disclosure, a first waveguide that extends from the light incident surface (first surface) of the semiconductor substrate to the opposite surface (second surface) is provided on the semiconductor substrate in which a photoelectric conversion unit is embedded for each pixel, and a condensing member that guides incident light to the first waveguide is disposed on the first surface side of the semiconductor substrate. As a result, the light receiving area of the incident light in the photoelectric conversion unit is enlarged.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a cross-sectional schematic view showing an example of the configuration of a photodetection device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a plan schematic view showing an example of the configuration of the photodetection device shown in FIG. 1. [Figure 3] FIG. 3 is a block diagram showing an example of the schematic configuration of the photodetection device shown in FIG. 1. [Figure 4] FIG. 4 is a plan schematic view showing an example of the configuration of a pixel portion of the photodetection device shown in FIG. 1. [Figure 5] FIG. 5 is a diagram showing an example of the circuit configuration of a unit pixel of the photodetection device shown in FIG. 1. [Figure 6A] FIG. 6A is a plan view (A) and a cross-sectional view (B) showing an example of the manufacturing process of the photodetection device shown in FIG. 1. [Figure 6B] FIG. 6B is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6A. [Figure 6C] FIG. 6C is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6B. [Figure 6D] FIG. 6D is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6C. [Figure 6E] FIG. 6E is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6D. [Figure 6F]FIG. 6F is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6E. [Figure 6G] FIG. 6G is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6F. [Figure 6H] FIG. 6H is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6G. [Figure 6I] FIG. 6I is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6H. [Figure 6J] FIG. 6J is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6I. [Figure 6K] FIG. 6K is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6J. [Figure 6L] FIG. 6L is a plan view (A) and a cross-sectional view (B) showing the process following FIG. 6K. [Figure 7] FIG. 7 is a schematic cross-sectional view showing an example of the configuration of a photodetection device according to Modification Example 1 of the present disclosure. [Figure 8] FIG. 8 is a schematic plan view showing an example of the configuration of the photodetection device shown in FIG. 7. [Figure 9] FIG. 10 is a schematic plan view showing another example of the configuration of the photodetection device shown in FIG. 7. [Figure 10] FIG. 10 is a schematic cross-sectional view showing an example of the configuration of a photodetection device according to Modification Example 2 of the present disclosure. [Figure 11] FIG. 11 is a schematic cross-sectional view showing an example of the configuration of a photodetection device according to Modification Example 3 of the present disclosure. [Figure 12] FIG. 12 is a schematic plan view showing an example of the configuration of the photodetection device shown in FIG. 11. [Figure 13A] FIG. 13A is a schematic plan view showing an example of the layout of a waveguide of a photodetection device according to Modification Example 4 of the present disclosure. [Figure 13B] FIG. 13B is a schematic plan view showing another example of the layout of a waveguide of a photodetection device according to Modification Example 4 of the present disclosure. [Figure 14] FIG. 14 is a schematic cross-sectional view showing an example of the configuration of a photodetection device according to Modification Example 5 of the present disclosure. [Figure 15] Figure 15 is a functional block diagram showing an example of an electronic device (camera) using the light detection device shown in Figure 1. [Figure 16A] Figure 16A is a schematic diagram showing an example of the overall configuration of a photodetection system using the photodetector shown in Figure 1. [Figure 16B] Figure 16B is a diagram showing an example of the circuit configuration of the photodetection system shown in Figure 16A. [Figure 17] Figure 17 shows an example of a schematic configuration of an endoscopic surgical system. [Figure 18] Figure 18 is a block diagram showing an example of the functional configuration of a camera head and CCU. [Figure 19] Figure 19 is a block diagram showing an example of a schematic configuration of a vehicle control system. [Figure 20] Figure 20 is an explanatory diagram showing an example of the installation location of the external information detection unit and the imaging unit. [Modes for carrying out the invention]

[0010] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following embodiment. Furthermore, the present 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 (Example of a photodetector in which a waveguide is embedded in a semiconductor substrate having a photoelectric conversion unit for each pixel) 2. Variations 2-1. Variation 1 (Another example of the configuration of a photodetector) 2-2. Modification Example 2 (Another example of the configuration of a photodetector) 2-3. Modification 3 (Another example of the configuration of a photodetector) 2-4. Modification 4 (Another example of the configuration of a photodetector) 2-5. Modification 5 (Another example of the configuration of a photodetector) 3. Examples of application 4. Application Examples

[0011] <1. Embodiment> Figure 1 schematically shows an example of a cross-sectional configuration of a photodetector (photodetector 1) according to an embodiment of this disclosure. Figure 2 schematically shows an example of a planar configuration of the photodetector 1 shown in Figure 1. The photodetector 1 is applicable to, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras, and has an effective pixel region (pixel section 100) in which a plurality of pixels are arranged in a matrix in two dimensions as an imaging area. The photodetector 1 is, for example, a so-called back-illuminated imaging device in this CMOS image sensor.

[0012] In this embodiment, the photodetector 1 has a photoelectric conversion unit 12 embedded in a semiconductor substrate 11 having a first surface 11S1 that serves as the light incident surface and a second surface 11S2 opposite to the first surface 11S1, with each unit pixel P embedded in the substrate. The semiconductor substrate 11 also has a waveguide 14 embedded in it that extends from the first surface 11S1 toward the second surface 11S2. A light guide unit 24 is provided on the first surface 11S1 side of the semiconductor substrate 11, so that light in a specific wavelength band to be detected from the incident light L is guided to the desired waveguide 14.

[0013] Here, the semiconductor substrate 11 corresponds to a specific example of a "semiconductor substrate" as one embodiment of the present disclosure. The waveguide 14 corresponds to a specific example of a "first waveguide" as one embodiment of the present disclosure. The light guide 24 corresponds to a specific example of a "light concentrating member" as one embodiment of the present disclosure.

[0014] [Outline configuration of the photodetector] Figure 3 is a block diagram showing an example of the schematic configuration of the photodetector 1. Figure 4 schematically shows an example of the configuration of the pixel section 100 of the photodetector 1. The photodetector 1 captures incident light (image light) from a subject via an optical lens system (e.g., optical system 1001, see Figure 15), converts the amount of light of the incident light 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 a pixel section 100 as an imaging area on a semiconductor substrate 11. Around the pixel section 100 are, for example, a pixel control unit 111, a signal processing unit 112, a control unit 113, and a processing unit 114. The photodetector 1 is also provided with, for example, a plurality of control lines Lread and a plurality of signal lines VSL.

[0015] In the pixel section 100, for example, multiple unit pixels P are arranged in a matrix in a two-dimensional manner. For example, control lines Lread (specifically row selection lines and reset control lines) are wired to each pixel row of unit pixels P, and signal lines VSL are wired to each pixel column.

[0016] The control line Lread is a signal line capable of transmitting signals to control a unit pixel P, and is connected to the pixel control unit 111 and the unit pixel P of the pixel unit 100. The control line Lread is configured to transmit control signals for reading signals from the unit pixel P. The control line Lread can also be called a drive line (pixel drive line) that transmits signals to drive the unit pixel P.

[0017] A signal line VSL is a signal line capable of transmitting a signal from a unit pixel P, and is connected to the unit pixel P of the pixel unit 100 and the signal processing unit 112. In the pixel unit 100, for example, one or more signal lines VSL are wired to each pixel row, which is composed of multiple unit pixels P arranged vertically (in the column direction). The signal line VSL is configured to transmit the signal output from the unit pixel P. In the photodetector 1, multiple signal lines VSL may be provided for a single pixel row.

[0018] The pixel control unit 111 is configured to control each unit pixel P of the pixel unit 100. The pixel control unit 111 is a control circuit and is composed of multiple circuits, such as a buffer, a shift register, and an address decoder. The pixel control unit 111 generates a signal for controlling the unit pixel P and outputs it to each unit pixel P of the pixel unit 100 via the control line Lread. The pixel control unit 111 is controlled by the control unit 113 and controls the unit pixels P of the pixel unit 100.

[0019] The pixel control unit 111 generates signals to control the unit pixels P, such as signals to control the transfer transistor of the unit pixel P, signals to control the selection transistor, and signals to control the reset transistor, and supplies these signals to each unit pixel P via the control line Lread. The pixel control unit 111 can control the reading of pixel signals from each unit pixel P. The pixel control unit 111 can also be described as a pixel drive unit configured to drive each unit pixel P. Note that the pixel control unit 111 and the control unit 113 together can also be referred to as the pixel control unit.

[0020] The signal processing unit 112 is configured to process the signals of the input pixels. The signal processing unit 112 is a signal processing circuit and includes, for example, a load circuit, an analog-to-digital (AD) conversion circuit, and a horizontal selection switch. The load circuit is, for example, composed of a current source capable of supplying current to the amplification transistor of a unit pixel P. The load circuit, together with the amplification transistor of the unit pixel P, constitutes a source follower circuit.

[0021] The signal processing unit 112 may have an amplification circuit configured to amplify the signal read from the unit pixel P via the signal line VSL. Load circuits, amplification circuits, and AD conversion circuits, etc., are provided, for example, for each of the multiple signal lines VSL. Load circuits, amplification circuits, and AD conversion circuits, etc., may be provided for each pixel row of the pixel unit 100.

[0022] The signals output from each unit pixel P selected and scanned by the pixel control unit 111 are input to the signal processing unit 112 via the signal line VSL. The signal processing unit 112 can perform signal processing such as AD conversion and correlated double sampling (CDS) of the unit pixel P signals. The signals of each unit pixel P transmitted through each of the signal lines VSL are processed by the signal processing unit 112 and output to the processing unit 114.

[0023] The processing unit 114 is configured to perform signal processing on the input signal. The processing unit 114 is a processing circuit and consists of, for example, circuits that perform various signal processing on pixel signals. The processing unit 114 may also include a processor and memory. The processing unit 114 performs signal processing on the pixel signal input from the signal processing unit 112 and outputs the processed pixel signal. The processing unit 114 can perform various signal processing, such as noise reduction processing and gradation correction processing.

[0024] The control unit 113 is configured to control each part of the light detection device 1. The control unit 113 receives data such as a clock and operating mode commands from an external source, and can output data such as internal information of the light detection device 1. The control unit 113 is a control circuit and, for example, has a timing generator configured to generate various timing signals. Based on the various timing signals (pulse signals, clock signals, etc.) generated by the timing generator, the control unit 113 performs drive control of the pixel control unit 111 and the signal processing unit 112, etc.

[0025] The pixel unit 100, the pixel control unit 111, the signal processing unit 112, etc., may be provided on a single substrate. Alternatively, the pixel control unit 111, the signal processing unit 112, the control unit 113, and the processing unit 114, etc., may be provided on a single semiconductor substrate, or they may be provided on multiple semiconductor substrates. The photodetector 1 may have a laminated structure formed by stacking multiple substrates. Some or all of the signal processing unit 112, the control unit 113, and the processing unit 114 may be integrally configured.

[0026] The pixel section 100 is a region that generates an image generation signal by photoelectric conversion of the subject image formed by the imaging lens in a photodiode (PD) provided for each unit pixel P. A first dummy pixel region that generates a pixel signal to assist in image generation may be provided at the periphery of the pixel section 100. Furthermore, a second dummy pixel region that does not generate a pixel signal may be provided outside the first dummy pixel region.

[0027] [Circuit configuration of a unit pixel] Figure 5 shows an example of the circuit configuration of a unit pixel P of the photodetector 1 shown in Figure 1. The unit pixel P includes, for example, a photoelectric conversion unit 12 and a readout circuit 31. The photoelectric conversion unit 12 is configured to receive light and generate a signal. The readout circuit 31 is configured to output a signal based on the photoelectrically converted charge. The readout circuit 31 can read out the pixel signal based on the charge photoelectrically converted by the photoelectric conversion unit 12.

[0028] The photoelectric conversion unit 12 is a so-called light-receiving element and is configured to generate electric charge through photoelectric conversion. The photoelectric conversion unit 12 is, for example, a photodiode (PD) and converts incident light into electric charge. The photoelectric conversion unit 12 can generate an electric charge corresponding to the amount of light received by performing photoelectric conversion.

[0029] The readout circuit 31, as an example, includes a transfer transistor TRG, a floating diffusion transistor FD, an amplification transistor AMP, a selection transistor SEL, and a reset transistor RST. The transfer transistor TRG, the amplification transistor AMP, the selection transistor SEL, and the reset transistor RST are MOS transistors (MOSFETs) having gate, source, and drain terminals, respectively.

[0030] For example, the transfer transistor TRG, the amplification transistor AMP, the selection transistor SEL, and the reset transistor RST are each composed of NMOS transistors. Note that each transistor constituting the readout circuit 31 may be composed of PMOS transistors.

[0031] The transfer transistor TRG is configured to transfer the charge photoelectrically converted in the photoelectric conversion unit 12 to the floating diffusion FD. The transfer transistor TRG is controlled by the signal STRG to electrically connect or disconnect the photoelectric conversion unit 12 and the floating diffusion FD. The transfer transistor TRG can transfer the charge photoelectrically converted and stored in the photoelectric conversion unit 12 to the floating diffusion FD.

[0032] The floating diffusion FD is a storage unit and is configured to store the transferred charge. The floating diffusion FD can store the charge photoelectrically converted by the photoelectric conversion unit 12. The floating diffusion FD can also be described as a storage unit capable of holding the transferred charge. The floating diffusion FD stores the transferred charge and converts it into a voltage corresponding to the capacitance of the floating diffusion FD.

[0033] The amplification transistor AMP is configured to generate and output a signal based on the charge accumulated in the floating diffusion FD. The amplification transistor AMP can generate and output a signal based on the charge converted by the photoelectric conversion unit 12.

[0034] The gate of the amplification transistor AMP is electrically connected to a floating diffusion diode (FD), and the voltage converted by the floating diffusion diode is input to it. The drain of the amplification transistor AMP is connected to a power line, for example, to which the power supply voltage VDD is supplied.

[0035] The source of the amplification transistor AMP is connected to the signal line VSL via the selection transistor SEL. The amplification transistor AMP is configured to generate a signal based on the charge accumulated in the floating diffusion FD, i.e., a signal based on the voltage of the floating diffusion FD, and output it to the signal line VSL.

[0036] The selection transistor SEL is configured to control the output of the pixel signal. The selection transistor SEL is electrically connected in series with, for example, the amplification transistor AMP. The selection transistor SEL is controlled by the signal SSEL and is configured to output the signal from the amplification transistor AMP to the signal line VSL. The selection transistor SEL can control the timing of the pixel signal output.

[0037] The selection transistor SEL is configured to output a signal based on the charge converted by the photoelectric conversion unit 12. The selection transistor SEL can output the pixel signal of a unit pixel P to the signal line VSL. The selection transistor SEL may be electrically connected in series between the power line to which the power supply voltage VDD is supplied and the amplification transistor AMP. The selection transistor SEL may also be omitted as appropriate.

[0038] The reset transistor RST is configured to reset the voltage of the floating diffusion FD. The reset transistor RST is electrically connected to a power line to which, for example, the power supply voltage VDD is supplied, and is configured to reset the charge of a unit pixel P.

[0039] The reset transistor RST is controlled by the signal SRST and can reset the charge accumulated in the floating diffusion FD and reset the voltage of the floating diffusion FD. The reset transistor RST can, for example, electrically connect the power line to the floating diffusion FD and discharge the charge accumulated in the floating diffusion FD. The reset transistor RST can also discharge the charge accumulated in the photoelectric conversion unit 12 via the transfer transistor TRG.

[0040] The pixel control unit 111 of the light detection device 1 supplies control signals to the gates of each unit pixel P, such as the transfer transistor TRG, selection transistor SEL, and reset transistor RST, via the control line Lread, to turn the transistors on (conducting) or off (non-conducting).

[0041] The multiple control lines Lread for each pixel row of the light detection device 1 include, as an example, wiring that transmits the signal STRG which controls the transfer transistor TRG, wiring that transmits the signal SSEL which controls the selection transistor SEL, and wiring that transmits the signal SRST which controls the reset transistor RST.

[0042] The readout circuit 31 may be configured to allow changing the conversion efficiency (gain) when converting charge to voltage. For example, the readout circuit 31 may have a switching transistor used to set the conversion efficiency. The switching transistor may be electrically connected, for example, between the floating diffusion transistor FD and the reset transistor RST.

[0043] In the readout circuit 31, when the switching transistor is turned on, the capacitance added to the floating diffusion FD of the unit pixel P increases, and the conversion efficiency is switched. The switching transistor can change the conversion efficiency by switching the capacitance connected to the gate of the amplification transistor AMP.

[0044] The transfer transistor TRG, selection transistor SEL, reset transistor RST, and switching transistors are controlled on and off by the pixel control unit 111. The pixel control unit 111 controls the readout circuit 31 of each unit pixel P to output a pixel signal from each unit pixel P to the signal line VSL. The pixel control unit 111 can control the reading of the pixel signal from each unit pixel P to the signal line VSL.

[0045] [Configuration of the photodetector] As described above, the light detection device 1 is a back-illuminated imaging device, and each of the multiple unit pixels P arranged in a matrix in two dimensions in the pixel section 100 has a configuration in which, for example, a light receiving section 10, an optical layer 20 provided on the light incident side S1 of the light receiving section 10, and a multilayer wiring layer 30 provided on the side opposite to the light incident side S1 of the light receiving section 10 are stacked. As described above, the light detection device 1 has a pixel section 100 in which the multiple unit pixels P are arranged in a matrix in two dimensions, and a peripheral section surrounding the pixel section 100. The light receiving section 10, the optical layer 20, and the multilayer wiring layer 30 are provided, for example, across the pixel section 100 and the peripheral section. The optical layer 20 includes a light guide section 24 which is composed of, for example, a plurality of structures 24A which are nanostructures and a medium 24B that fills the spaces between adjacent plurality of structures 24A.

[0046] The light-receiving unit 10 includes a semiconductor substrate 11 having opposing first surfaces 11S1 and second surfaces 11S2, and a plurality of photoelectric conversion units 12 embedded in the semiconductor substrate 11 for each unit pixel P. The light-receiving unit 10 further includes a separation groove 13 and a waveguide 14.

[0047] The semiconductor substrate 11 is made of, for example, a silicon substrate (Si). The semiconductor substrate 11 may also be an SOI (Silicon On Insulator) substrate, a SiGe (Silicon Germanium) substrate, a SiC (Silicon Carbide) substrate, etc. The semiconductor substrate 11 may be made of a III-V compound semiconductor material, or it may be formed using other semiconductor materials. The first surface 11S1 of the semiconductor substrate 11 is the light-receiving surface (light incident surface). The second surface 11S2 of the semiconductor substrate 11 is the element formation surface on which elements such as transistors are formed. A gate electrode, a gate insulating film, etc., are provided on the second surface 11S2 of the semiconductor substrate 11.

[0048] The photoelectric conversion unit 12 is, for example, a Positive Intrinsic Negative (PIN) type photodiode (PD) and has a pn junction in a predetermined region of the semiconductor substrate 11. The photoelectric conversion unit 12 is formed by embedding one unit for each unit pixel P, for example.

[0049] The separation groove 13 is provided between adjacent unit pixels P. In other words, the separation groove 13 is provided so as to surround the unit pixels P, and in the pixel portion 100, it is provided, for example, in a grid pattern. The separation groove 13 electrically and optically separates adjacent unit pixels P, and extends, for example, from the first surface 11S1 side to the second surface 11S2 side of the semiconductor substrate 11.

[0050] The separation groove 13 includes, for example, a light-reflecting film 13A that covers its sides and bottom, and an insulating film 13B that fills the groove covered by the light-reflecting film 13A. The light-reflecting film 13A is formed of, for example, a material having a reflectance of 90% or more to incident light L. Examples of such materials include silver (Ag), aluminum (Al), copper (Cu), gold (Au), platinum (Pt), rhodium (Rh), and their alloys. Examples of constituent materials for the insulating film 13B include silicon oxide (SiO), silicon nitride (SiN), and aluminum oxide (AlO).

[0051] The isolation groove 13 may have, for example, a Deep Trench Isolation (DTI) structure. Alternatively, the isolation groove 13 may have a Full Trench Isolation (FTI) structure that penetrates between the first surface 11S1 and the second surface 11S2 of the semiconductor substrate 11. Within the DTI structure and FFTI structure, where the side and bottom surfaces are covered with a light-reflecting film 13A, an air gap may be formed instead of an insulating film 13B.

[0052] Waveguide 14 is for guiding light incident from the light incident side S1 to the side of the photoelectric conversion unit 12, and extends, for example, from the first surface 11S1 side to the second surface 11S2 side of the semiconductor substrate 11. Waveguide 14 is provided, for example, between adjacent unit pixels P.

[0053] Specifically, the waveguide 14 is provided between a plurality of separation grooves 13 that are arranged in a grid pattern in the pixel section 100, extending in the Y-axis direction in a plan view and parallel in the X-axis direction. In other words, for example, in the pixel section 100, a plurality of separation grooves 13 arranged in a grid pattern in a plan view, parallel in the X-axis direction, are replaced by waveguides 14 every other row. To put it another way, a plurality of unit pixels P arranged in a matrix in two dimensions in the pixel section 100 have, for example, a roughly square shape with four sides in a plan view, the waveguide 14 is located on one of the four sides, and the separation grooves 13 are provided on the three sides excluding this one side. In other words, one of the four sides of the photoelectric conversion section 12 embedded in each unit pixel P faces the waveguide 14, and the other three sides face the separation grooves 13 covered with the light-reflecting film 13A.

[0054] The waveguide 14 is formed using a material with a lower refractive index than the semiconductor substrate 11. An example of a material with a lower refractive index than the semiconductor substrate 11 is silicon oxide (SiO). The waveguide 14 has, for example, a DTI structure. Alternatively, the waveguide 14 may have a Full Trench Isolation (FTI) structure that penetrates between the first surface 11S1 and the second surface 11S2 of the semiconductor substrate 11.

[0055] A dielectric layer 15 is further provided on the first surface 11S1 of the semiconductor substrate 11. The dielectric layer 15 extends from the first surface 11S1 of the semiconductor substrate 11 to the side and bottom surfaces of the separation groove 13. The dielectric layer 15 within the separation groove 13 is provided between the semiconductor substrate 11 and the light-reflecting film 13A. The dielectric layer 15 may be, for example, a film having a positive fixed charge or a film having a negative fixed charge.

[0056] Examples of constituent materials for the dielectric layer 15 include semiconductor materials or conductive materials having a band gap wider than the band gap of the semiconductor substrate 11. Specifically, for example, hafnium oxide (HfO) x ), aluminum oxide (AlO x) Zirconium oxide (ZrO x ) Tantalum oxide (TaO x ) Titanium oxide (TiO x ) Lanthanum oxide (LaO x ) Praseodymium oxide (PrO x ) Cerium oxide (CeO x ) Neodymium oxide (NdO x ) Promethium oxide (PmO x ) Samarium oxide (SmO x ) Europium oxide (EuO x ) Gadolinium oxide (GdO x ) Terbium oxide (TbO x ) Dysprosium oxide (DyO x ) Holmium oxide (HoO x ) Thulium oxide (TmO x ) Ytterbium oxide (YbO x ) Lutetium oxide (LuO x ) Yttrium oxide (YO x ) Hafnium nitride (HfN x ) Aluminum nitride (AlN x ) Hafnium oxynitride (HfO x N y ) and aluminum oxynitride (AlO x N y ) and the like can be mentioned. The dielectric layer 15 may be a single-layer film or a laminated film made of different materials.

[0057] A low refractive index layer 16 may be provided on the first surface 11S1 of the semiconductor substrate 11. The low refractive index layer 16 is for preventing reflection at the first surface 11S1 of the semiconductor substrate 11. For example, it is a structure in which the low refractive index material constituting the waveguide 14 extends above the first surface 11S1 of the semiconductor substrate 11.

[0058] s The optical layer 20 includes, for example, a spacer layer 21, an inner lens 22, a planarization layer 23, a light guiding portion 24, and an antireflection film 25, and is configured to guide the light incident from the light incident side S1 to the light receiving portion 10 side.

[0059] The spacer layer 21 is provided between the light-receiving section 10 and the light-guiding section 24. The spacer layer 21 is formed, for example, over the pixel section 100 and the peripheral section. The spacer layer 21 can be formed using, for example, silicon oxide (SiO), silicon nitride (SiN), or aluminum oxide (AlO).

[0060] The spacer layer 21 may be formed using a material with a low refractive index in addition to the insulating material described above, or it may be formed of another material that transmits light in the wavelength range to be measured. The spacer layer 21 can also be described as a transparent layer that transmits light. The thickness of the spacer layer 21 is, for example, 2 μm or more and 3 μm or less.

[0061] The inner lens 22 is provided between the light-receiving section 10 and the spacer layer 21. The inner lens 22 is for guiding the light spectrally separated by the light guide section 24 to the waveguide 14, and is positioned above the waveguide 14 (see, for example, Figure 6J(A)).

[0062] The inner lens 22 is formed using, for example, a material with a high refractive index. Examples of materials with a high refractive index include organic materials such as episulfide resins, thietan compounds, and their resins. The inner lens 22 has, for example, a cylindrical lens shape, but is not limited to this.

[0063] Note that the inner lens 22 can be omitted.

[0064] The planarization layer 23 is intended to fill the step on the upper surface of the spacer layer 21 and flatten the surface on the light incident side S1. The planarization layer 23 can be formed using, for example, silicon oxide (SiO), silicon nitride (SiN), or aluminum oxide (AlO).

[0065] The light guide section 24 is configured as a light guide element capable of guiding light by, for example, providing a phase delay to the incident light. The light guide section 24 is a light guide element utilizing metamaterial (metasurface) technology. The light guide section 24 can also be called a metasurface layer (or metamaterial layer).

[0066] The light guide unit 24 has a plurality of structures 24A and a medium 24B provided around the plurality of structures 24A. The light guide unit 24 uses the plurality of nanostructures 24A to propagate light towards the photoelectric conversion unit 12. Light from the object to be measured is incident on the light guide unit 24. Light that has passed through an optical system such as an imaging lens is incident on the plurality of structures 24A. The plurality of structures 24A have a size of less than or equal to a predetermined wavelength of the incident light, for example, a size of less than or equal to the wavelength band of visible light. The plurality of structures 24A may also have a size of less than or equal to the wavelength band of infrared light.

[0067] Each of the multiple structures 24A is, for example, a columnar (pillar-shaped) structure and can be called a nanopillar. The multiple structures 24A can be called a metasurface element. For example, the multiple structures 24A have a cylindrical shape. The multiple structures 24A are arranged so as to be aligned with each other in the X-axis direction or the Y-axis direction with the medium 24B in between.

[0068] The shapes of the multiple structures 24A can be changed as appropriate, and each may be circular or rectangular in plan view. The shapes of the multiple structures 24A may also be elliptical, polygonal, cross-shaped, or other shapes (for example, freeform).

[0069] Multiple structures 24A are also referred to as metaatoms, nanoatoms, nanoposts, metasurface structures, microstructures, etc.

[0070] The medium 24B is provided to fill the periphery of the multiple structures 24A. The multiple structures 24A are provided within the medium 24B, and it can also be said that they are arranged by replacing a part of the medium 24B. The medium 24B can also be called a medium layer or a protective layer (protective member).

[0071] In the light guide section 24, multiple structures 24A are arranged at intervals less than or equal to a predetermined wavelength of incident light. As an example, multiple structures 24A are provided in the X-axis and Y-axis directions at intervals less than or equal to the wavelength band of visible light. In the case of a unit pixel P, multiple structures 24A may be arranged at intervals less than or equal to the wavelength band of infrared light.

[0072] Multiple structures 24A have refractive indices different from those of the surrounding medium 24B. For example, multiple structures 24A have refractive indices higher than those of the medium 24B.

[0073] Examples of constituent materials for the multiple structures 24A include titanium oxide (TiO), silicon, polysilicon (Poly-Si), amorphous silicon (a-Si), and germanium (Ge).

[0074] Multiple structures 24A may be formed using elements such as titanium (Ti), hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum (Ta), indium (In), and niobium (Nb), or their oxides, nitrides, oxynitrides, or composites thereof. Multiple structures 24A may also be formed by including other metal compounds (metal oxides, metal nitrides, etc.).

[0075] Multiple structures 24A may be formed using GaP, GaN, GaAs, or SiC, etc. Multiple structures 24A may be formed using silicon oxide (SiO), silicon nitride (SiN), silicon oxide nitride (SiON), silicon carbide (SiC), oxygen-doped silicon carbide (SiOC), or other silicon compounds. Multiple structures 24A may be composed of materials different from each other.

[0076] The medium 24B is composed of, for example, an inorganic material such as an oxide, nitride, or oxynitride. The medium 24B may be formed using, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxide nitride (SiON), silicon carbide (SiC), oxygen-doped silicon carbide (SiOC), or other silicon compounds. The medium 24B may also be formed using TEOS.

[0077] The medium 24B may be formed using a siloxane resin, a styrene resin, or an acrylic resin, etc. The medium 24B may also be composed of a material in which fluorine is contained in any of these resins. The medium 24B may also be formed using a material in which beads (fillers) having a higher (or lower) refractive index than the resin are embedded in any of these resins.

[0078] The materials of the multiple structures 24A and the medium 24B can be selected according to the refractive index difference with the surrounding medium, the wavelength band of the incident light to be measured, etc. Note that some of the multiple structures 24A and the medium 24B may be made of air. For example, the multiple structures 24A may be made including air (voids).

[0079] The light guide 24 can control the wavefront of light by, for example, generating a phase delay in the incident light due to the difference in refractive index between the multiple structures 24A and the surrounding medium. The light guide 24 can adjust the propagation direction of light by, for example, imparting a phase delay to the incident light using the multiple structures 24A and the medium 24B.

[0080] The materials (optical constants of each material), the size (width (diameter), height, etc.), and pitch (arrangement interval) of the multiple structures 24A and medium 24B are determined so that light of a desired wavelength range from the light source being measured travels in a desired direction. For example, the material (refractive index), dimensions, and pitch of the multiple structures 24A, and the material (refractive index) of the medium 24B may be set.

[0081] As an example, in the photodetector 1, the material, size, and number of arrangements of multiple structures 24A are determined so that, of the incident light L, light in a specific wavelength band to be detected proceeds to the photoelectric conversion unit 12 of the desired unit pixel P. For example, as shown in Figure 1, the multiple structures 24A are configured to spectrally separate the incident light L into light in the red (R) wavelength band (red light Lr), light in the green (G) wavelength band (green light Lg), and light in the blue (B) wavelength band (blue light Lb), and guide them to the corresponding unit pixels Pr, Pg, and Pb, respectively.

[0082] In the light detection device 1, the material, size, number, etc., of the multiple columnar structures 37 may be determined for each unit pixel P. For example, the multiple columnar structures 37 provided for unit pixels Pr, Pg, and Pb may be formed to have different sizes (e.g., width, height), placement positions, etc.

[0083] In other words, the light guide unit 24 is configured, for example, as a spectrometer (spectroscopic element) capable of spectrally separating incident light. The optical layer 20 (or light guide unit 24) can also be called a splitter (color splitter). The optical layer 20 can also be called a color splitter layer or a wavelength separation layer. The optical layer 20 (or light guide unit 24) can also be called an optical element configured to redirect light.

[0084] Here, unit pixel Pr is capable of generating the R component pixel signal of RGB. Unit pixel Pg is capable of generating the G component pixel signal of RGB. Unit pixel Pb is capable of generating the B component pixel signal of RGB. The light detection device 1 can obtain RGB pixel signals.

[0085] In the pixel section 100, multiple unit pixels Pr, multiple unit pixels Pg, and multiple unit pixels Pb are arranged repeatedly. In the photodetector 1, as shown in Figure 2 as an example, the unit pixels Pr, unit pixels Pg, and unit pixels Pb are arranged in this order in two rows each, repeatedly in the X-axis direction.

[0086] The anti-reflective coating 25 is provided so as to cover the light incident surface of the light guide portion 24 and reduces (suppresses) reflection. The anti-reflective coating 25 is made of a silicon compound such as silicon nitride (SiN) or silicon oxide (SiO). The anti-reflective coating 25 may also be made of a metal compound or other material. The anti-reflective coating 25 may be made by laminating multiple films.

[0087] The multilayer wiring layer 30 is laminated on the second surface 11S2 side of the semiconductor substrate 11. The multilayer wiring layer 30 includes, for example, a conductive film and an insulating film, and has multiple wirings, vias, etc. The multilayer wiring layer 30 has a configuration in which multiple wirings are laminated with an insulating film acting as an interlayer insulating film. The multilayer wiring layer 30 includes, for example, two or three or more wiring layers.

[0088] The wiring of the multilayer wiring layer 30 is formed using a metallic material such as aluminum (Al), copper (Cu), or tungsten (W). Alternatively, the wiring of the multilayer wiring layer 30 may be made of polysilicon (Poly-Si) or other conductive materials. The interlayer insulating film can be formed using, for example, silicon oxide (SiO), silicon nitride (SiN), or silicon oxynitride (SiON).

[0089] The semiconductor substrate 11 and the multilayer wiring layer 30 are provided with the above-described readout circuit 31, for example, for each unit pixel P or for each of multiple unit pixels P. In addition to the above-described readout circuit 31, the multilayer wiring layer 30 may also be formed with a pixel control unit 111, a signal processing unit 112, a control unit 113, and a processing unit 114, for example.

[0090] [Manufacturing method for a photodetector] Figures 6A to 6L show the manufacturing process of the light detection device 1 in order of steps.

[0091] First, as shown in Figures 6A(A) and (B), grooves H1 extending from the first surface 11S1 to the second surface 11S2 of the semiconductor substrate 11 are formed, for example, in a grid pattern, using photolithography technology. At this time, as shown in Figure 6A(A), it is preferable to leave the semiconductor substrate 11 at the intersections of the grooves H1 extending in the X-axis direction and the Y-axis direction, respectively. This suppresses color mixing between adjacent unit pixels P.

[0092] Furthermore, if the light-reflective film 13A is formed on the entire side and bottom surfaces of the groove H1 that will become the separation groove 13, the semiconductor substrate 11 at the intersection of the groove H1 that will become the separation groove 13 does not need to be left. In other words, if the light-reflective film 13A is formed on the entire side and bottom surfaces of the groove H1 that will become the separation groove 13, the semiconductor substrate 11 may be left only at the intersection of the groove H1 that will become the separation groove 13 and the groove H1 in which the waveguide 14 is formed.

[0093] Next, as shown in Figures 6B(A) and (B), a dielectric layer 15 is formed on the first surface 11S1 of the semiconductor substrate 11 and on the side and bottom surfaces of the groove H1.

[0094] Next, as shown in Figures 6C(A) and (B), a light-reflective film 13A is formed on the first surface 11S1 of the semiconductor substrate 11 and on the side and bottom surfaces of the groove H1.

[0095] Next, as shown in Figures 6D(A) and (B), a resist film 41 is formed on the first surface 11S1 of the semiconductor substrate 11, except for the area where the waveguide 14 is formed. Subsequently, as shown in Figures 6D(A) and (B), the resist film 41 is used as a mask to remove the light-reflecting film 13A formed in the groove H1 where the waveguide 14 is formed by etching, thereby forming groove H2.

[0096] Next, the resist film 41 is removed as shown in Figures 6E (A) and (B).

[0097] Next, as shown in Figures 6F (A) and (B), a film with a lower refractive index than the semiconductor substrate 11, such as an SiO film, is deposited on the first surface 11S1 of the semiconductor substrate 11, filling the grooves H1 and H2 on which the light-reflecting film 13A has been deposited. This forms the separation groove 13, the waveguide 14, and the low refractive index layer 16.

[0098] Next, as shown in Figures 6G(A) and (B), a transparent resin film 22A is formed on the low refractive index layer 16.

[0099] Next, as shown in Figures 6H(A) and (B), a resist film 42 is formed at a predetermined position on the resin film 22A.

[0100] Next, as shown in Figures 6I (A) and (B), the resist film 42 is baked, and then, as shown in Figures 6J (A) and (B), the resin film 22A is etched back using the resist film 42 as a mask. This forms the inner lens 22.

[0101] Next, as shown in Figures 6K(A) and (B), a spacer layer 21 is deposited on the low refractive index layer 16, for example, using chemical vapor deposition (CVD), so as to cover the inner lens 22.

[0102] Next, as shown in Figures 6L(A) and (B), a planarization layer 23 is formed on the spacer layer 21, and then the surface of the planarization layer 23 is planarized using, for example, chemical mechanical polishing (CMP). Subsequently, as shown in Figures 6L(A) and (B), a light guide portion 24 and an anti-reflective film 35 are formed sequentially on the planarization layer 23. With these steps, the light detection device 1 shown in Figure 1 is completed.

[0103] The manufacturing method described above is merely one example, and other manufacturing methods may be used.

[0104] [Effects / Effects] In the light detection device 1 of this embodiment, a waveguide 14 extending from the first surface 11S1 to the second surface 11S2 of the semiconductor substrate 11, which is the light incident surface, is embedded in the semiconductor substrate 11 in which the photoelectric conversion unit 12 is embedded for each unit pixel P. A light guide unit 24 is provided on the first surface 11S1 side of the semiconductor substrate 11 to guide the incident light L to the waveguide 14. This increases the light receiving area of ​​the incident light L in the photoelectric conversion unit 12. This will be explained below.

[0105] In recent years, the decrease in pixel sensitivity due to miniaturization has become a challenge.

[0106] As a countermeasure against the decrease in pixel sensitivity, a technology that scatters light using nanopost structures and spatially separates wavelengths to enlarge the effective light-gathering area for each color compared to a single pixel is attracting attention. Nanopost structures have a high refractive index relative to the surrounding medium, and a phase difference corresponding to the wavelength is created between the nanopost structure and the medium. Therefore, by optimizing the radius, length, and arrangement of the nanoposts, the visible wavelength band corresponding to each color pixel constituting the pixel unit can be distributed. This makes it possible to achieve higher sensitivity compared to full-color image sensors that acquire RGB color information using general color filters.

[0107] Incidentally, in image sensors that use nanopost structures as color splitters as described above, while quantum efficiency (Qe) improves, a problem arises in that the saturation signal amount (Qs) decreases as the pixels are miniaturized.

[0108] In contrast, in this embodiment, a waveguide 14 extending from the first surface 11S1 side of the semiconductor substrate 11, which is the light incident surface, toward the second surface 11S2 is embedded in the semiconductor substrate 11, in which a photoelectric conversion unit 12 is embedded for each unit pixel P, and a light guide unit 24 is arranged on the first surface 11S1 side of the semiconductor substrate 11. The light guide unit 24 is configured to guide light of a specific wavelength band to be detected from the incident light L to the desired waveguide 14. The light focused in the waveguide 14 propagates within the waveguide 14 and is incident on the side surface of the photoelectric conversion unit 12. As a result, the photoelectric conversion unit 12 can detect light not only from the light incident side S1 but also from the side surface of the photoelectric conversion unit 12, making it possible to improve Qs.

[0109] As a result of the above, the optical detection device 1 of this embodiment makes it possible to achieve pixel miniaturization.

[0110] Furthermore, in the light detection device 1 of this embodiment, the unit pixels P that detect any of the RGB colored light are arranged adjacent to each other in one direction (for example, in the X-axis direction), and the waveguide 14 is placed between these adjacent unit pixels P. As a result, the interval between receiving each of the RGB colored light is widened, making it possible to suppress color mixing.

[0111] Next, embodiments and modified examples 1 to 5 of the present 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.

[0112] <2. Variant> (2-1. Variation 1) Figure 7 schematically shows an example of a cross-sectional configuration of a photodetector (photodetector 1A) according to Modification 1 of the present disclosure. The photodetector 1A is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, and, similar to the above embodiment, is, for example, a so-called back-illuminated imaging device.

[0113] In this modified example, the photodetector 1A has a partition wall 26 and a color filter 27 arranged within the spacer layer 21. Except for this point, the photodetector 1A has substantially the same configuration as the photodetector 1 of the above embodiment.

[0114] The partition wall 26 is a frame provided at the boundary between adjacent unit pixels Pr, Pg, and Pb, and has an opening 26H for each unit pixel Pr, Pg, and Pb. In other words, it is provided so as to surround the unit pixels Pr, Pg, and Pb. For example, as will be described later, when the unit pixels Pr, Pg, and Pb are arranged according to a Bayer array, the partition wall 26 is provided in the pixel section 100, for example, in a grid pattern.

[0115] The partition wall 26 is designed to prevent light incident at an oblique angle from the light incident side S1 from leaking into adjacent unit pixels P of different colors. The partition wall 26 is constructed, for example, using a material with a lower refractive index than the color filter 27.

[0116] The partition wall 26 may also serve to shield the unit pixel P that determines the optical black level. In that case, the partition wall 26 is formed using a material that has light-shielding properties. Examples of such materials include tungsten (W), silver (Ag), copper (Cu), titanium (Ti), aluminum (Al), or alloys thereof. In addition, metal compounds such as TiN can be used as materials to form the partition wall 26. The partition wall 26 may be configured as a single layer or a multilayer film. In the case of a multilayer film, for example, a layer made of Ti, tantalum (Ta), W, cobalt (Co), or molybdenum (Mo), or alloys thereof, nitrides, oxides, or carbides may be provided as an underlayer.

[0117] The color filter 27 is configured to selectively transmit light in a predetermined wavelength band from the incident light L. The color filter 27 can be an RGB color filter, an infrared light transmitting filter, etc. The color filter 27 is provided above the photoelectric conversion unit 12, for example, for each unit pixel P or for each of several unit pixels P (i.e., for each predetermined number of unit pixels P).

[0118] For example, a unit pixel P equipped with a color filter that transmits red (R) light (red filter 27R) becomes a unit pixel Pr capable of generating a pixel signal of the R component. A unit pixel P equipped with a color filter that transmits green (G) light (green filter 27G) becomes a unit pixel Pg capable of generating a pixel signal of the G component. A unit pixel P equipped with a color filter that transmits blue (B) light (blue filter 27B) becomes a unit pixel Pb capable of generating a pixel signal of the B component.

[0119] In the light detection device 1A, the unit pixels Pr, Pg, and Pb are arranged, for example, according to a Bayer array. In the pixel section 100, 2x2 pixels, each consisting of one unit pixel Pr, two unit pixels Pg, and one unit pixel Pb, are repeatedly provided. The pixel section 100 has, for example, pixel rows in which unit pixels Pg and Pr are arranged alternately, and pixel rows in which unit pixels Pb and Pg are arranged alternately.

[0120] The color filter 27 is not limited to primary color (RGB) color filters, but may also be complementary color filters such as Cy (cyan), Mg (magenta), and Ye (yellow). A filter corresponding to W (white), that is, a filter that transmits light across the entire wavelength range of incident light, may also be provided. The color filter 27 may also be a filter that transmits infrared light. Furthermore, in pixels that receive white (W) light and perform photoelectric conversion, the color filter 27 does not need to be provided.

[0121] In the photodetector 1A, as shown in Figure 8, for example, each unit pixel P has a rectangular planar shape, and each of the RGB color filters 27R, 27G, and 27B is provided across two adjacent unit pixels P separated by a waveguide 14. In other words, in the photodetector 1A, two adjacent unit pixels P separated by a waveguide 14 containing each of the color filters 27R, 27G, and 27B can be considered as a single pixel capable of generating any of the RGB pixel signals. In this case, it can be said that the waveguide 14 is provided in such a way as to divide a single pixel, for example, into left and right halves.

[0122] Note that the arrangement of the unit pixels P and waveguide 14 is not limited to the example described above and can be set arbitrarily.

[0123] For example, as shown in Figure 9, if a plurality of unit pixels P having a roughly square planar shape are arranged in a matrix in two dimensions, and each of the four adjacent unit pixels P arranged in a 2x2 grid is provided with RGB color filters 27R, 27G, and 27B, the waveguide 14 may be provided between these four adjacent unit pixels P arranged in a 2x2 grid. If these four adjacent unit pixels P arranged in a 2x2 grid and provided with the respective color filters 27R, 27G, and 27B are considered as a single pixel, then the waveguide 14 can be said to be provided in a cross shape in a planar view, for example, so as to divide the single pixel in the upper, lower, left, and right directions.

[0124] Furthermore, if each color filter 27R, 27G, and 27B is arranged in a 2x2 grid with four adjacent unit pixels P, then in the pixel section 100, the unit pixels Pr, Pg, and Pb are arranged periodically in a 2x2 grid.

[0125] As described above, in this modified example, the partition wall 26 and the color filter 27 are arranged within the spacer layer 21. As a result, the spectral dispersion of light incident on the photoelectric conversion unit 12 provided in each unit pixel P is performed by the color filter 27, eliminating the need for spectral dispersion in the light guide unit 24. Even with this configuration, the photodetector 1A in this modified example can obtain the same effects as the photodetector 1 of the above embodiment.

[0126] (2-2. Variation 2) Figure 10 schematically shows an example of a cross-sectional configuration of a photodetector (photodetector 1B) according to Modification 2 of the present disclosure. The photodetector 1B is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, and, similar to the above embodiment, is, for example, a so-called back-illuminated imaging device.

[0127] In the above embodiment, an example was shown in which the separation groove 13 and the waveguide 14 are formed to the same depth, but the invention is not limited to this. In this modified example, the photodetector 1B has the waveguide 14 formed to be shallower than the separation groove 13. Except for this point, the photodetector 1B has substantially the same configuration as the photodetector 1 of the above embodiment.

[0128] Thus, in this modified photodetector 1B, the waveguide 14 is formed shallower than the separation groove 13, and the bottom of the waveguide 14 is separated from the second surface 11S2 of the semiconductor substrate 11, which has many defect sites and gettering sites. As a result, it is possible to suppress white spots and dark currents compared to the photodetector 1 of the above embodiment.

[0129] (2-3. Variation 3) Figure 11 schematically shows an example of a cross-sectional configuration of a photodetector (photodetector 1C) according to Modification 3 of this disclosure. Figure 12 schematically shows an example of a planar configuration of the photodetector 1C shown in Figure 11. Note that Figure 11 represents a cross-section corresponding to line II shown in Figure 12. The photodetector 1C is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, and, similar to the above embodiment, is, for example, a so-called back-illuminated imaging device.

[0130] In the embodiments described above, examples were shown in which the unit pixels Pr, Pg, and Pb have the same area, but the invention is not limited to this. In this modified example, the photodetector 1C has different areas for the unit pixels Pr, Pg, and Pb. Except for this point, the photodetector 1B has substantially the same configuration as the photodetector 1 of the embodiments described above.

[0131] Thus, in the modified photodetector 1C, for example, the areas of unit pixels Pr, Pg, and Pb are changed according to the sensitivity. Even with this configuration, the modified photodetector 1C can obtain the same effects as the photodetector 1 of the above embodiment.

[0132] (2-4. Modification 4) Figures 13A and 13B schematically represent an example of a planar layout of the waveguide 14 in an optical detection device according to Modification 4 of the present disclosure.

[0133] In the above embodiment, for example, an example was shown in which a waveguide 14 is provided between two adjacent unit pixels P in the X-axis direction. In the above modified example 1, for example, an example was shown in which a waveguide 14 is provided in a cross shape between four adjacent unit pixels P in the X-axis direction and the Y-axis direction, but the layout of the waveguide 14 is not limited to these.

[0134] For example, as shown in Figure 13A, a waveguide 14 having, for example, a circular planar shape may be embedded approximately in the center of the unit pixel P. For example, as shown in Figure 13B, multiple waveguides 14 having, for example, a circular planar shape may be embedded in the unit pixel P.

[0135] Even with this configuration, the same effects as in the above embodiment can be obtained.

[0136] (2-5. Modification 5) Figure 14 schematically shows an example of a cross-sectional configuration of a photodetector (photodetector 2) according to Modification 5 of this disclosure. The photodetector 2 is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras.

[0137] In the above embodiments and modifications 1 to 3, the present technology was described using a back-illuminated imaging device as an example, but it is not limited to this, and the present technology can also be applied to a front-illuminated imaging device.

[0138] As described above, the light detection device 2 is a surface-illuminated imaging device and has a multilayer wiring layer 50 between the light-receiving unit 10 and the optical layer 20. Except for this point, the light detection device 2 has substantially the same configuration as the light detection device 1 of the above embodiment.

[0139] The multilayer wiring layer 50, similar to the multilayer wiring layer 30 in the above embodiment, includes, for example, a conductive film and an insulating film, and has a plurality of wirings, vias, etc. The multilayer wiring layer 50 has a configuration in which a plurality of wirings are stacked with an insulating film acting as an interlayer insulating film. The multilayer wiring layer 50 includes, for example, two or three or more layers of wiring.

[0140] The wiring of the multilayer wiring layer 50 is composed of, for example, polysilicon (Poly-Si) or other conductive materials. The interlayer insulating film can be formed using, for example, silicon oxide (SiO), silicon nitride (SiN), or silicon oxynitride (SiON).

[0141] The semiconductor substrate 11 and the multilayer wiring layer 50 are provided with the above-described readout circuit 31, for example, for each unit pixel P or for each of multiple unit pixels P. In addition to the readout circuit 31, the multilayer wiring layer 50 may also have a pixel control unit 111, a signal processing unit 112, a control unit 113, and a processing unit 114, etc.

[0142] A waveguide 51 is further provided in the multilayer wiring layer 50. The waveguide 51 is for guiding light incident from the light incident side S1 to a waveguide 14 provided in the light receiving unit 10, and corresponds to a specific example of the "second waveguide" as one embodiment of the present disclosure. The waveguide 51 penetrates between the optical layer 20 side and the light receiving unit 10 side of the multilayer wiring layer 50. The waveguide 51, like the waveguide 14, is provided, for example, between adjacent unit pixels P.

[0143] Waveguide 51 has a core layer 51A and a cladding layer 51B surrounding the core layer 51A. The core layer 51A is formed of a material having a higher refractive index than the surrounding multilayer wiring layer 50. The cladding layer 51B is formed of a material having a lower refractive index than the surrounding multilayer wiring layer 50.

[0144] Thus, in this modified photodetector 2, a waveguide 51 is provided that penetrates the multilayer wiring layer 50, which is positioned between the light-receiving unit 10 and the optical layer 20. As a result, for example, light that has been spectrally separated by the light guide unit 24 and guided to the desired unit pixel P is guided to the waveguide 14 provided in the light-receiving unit 10 via the waveguide 51 that penetrates the multilayer wiring layer 50. Therefore, it becomes possible to miniaturize pixels even in a surface-illuminated imaging device.

[0145] <3. Application Examples> (Application Example 1) Furthermore, the light detection device described above (for example, light detection device 1) can be applied to various electronic devices such as imaging systems like digital still cameras and digital video cameras, mobile phones equipped with imaging functions, or other devices equipped with imaging functions.

[0146] Figure 15 is a block diagram showing an example of the configuration of electronic device 1000.

[0147] As shown in Figure 15, the electronic device 1000 includes an optical system 1001, a photodetector 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 the device 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 16A schematically shows an example of the overall configuration of a photodetection system 2000 equipped with a photodetector 1. Figure 16B 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 that emits infrared light L2, and a photodetector 2002 as a light-receiving unit having a photoelectric conversion element. For example, the photodetector 1 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 light L1 and light L2. Light L1 is light reflected from ambient light from the outside by the subject (object to be measured) 2100 (Figure 16A). Light L2 is light that has been emitted by the light-emitting device 2001 and then reflected by the subject 2100. Light L1 is, for example, visible light, and light L2 is, for example, infrared light. Light L1 is detectable in the photoelectric conversion unit of the photodetector 2002, and light L2 is detectable in the photoelectric conversion region of the photodetector 2002. Image information of the subject 2100 can be obtained from light L1, and distance information between the subject 2100 and the photodetector system 2000 can be obtained from 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, for example, a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). The detection method for light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can, for example, be the iTOF method, but is not limited to this. In the iTOF method, the photoelectric conversion unit can measure the distance to the subject 2100 by, for example, the time-of-flight (TOF). The detection method for light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can also be, for example, the structured light method or the stereo vision method. For example, in the structured light method, the distance between the photodetector 2000 and the subject 2100 can be measured by projecting a predetermined pattern of light onto the subject 2100 and analyzing the degree of distortion of the pattern. In the stereo vision method, for example, the distance between the photodetector 2000 and the subject can be measured by using two or more cameras to acquire two or more images of the subject 2100 from two or more different viewpoints. The light-emitting device 2001 and the photodetector 2002 can be synchronized and controlled by the system control unit 2003.

[0153] <4. Application Examples> (Examples of application to endoscopic surgical systems) The technology disclosed herein (the Technology) can be applied to a variety of products. For example, the Technology disclosed herein may be applied to an endoscopic surgical system.

[0154] Figure 17 shows an example of a schematic configuration of an endoscopic surgical system to which the technology described herein (the technology) may be applied.

[0155] Figure 17 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.

[0156] 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.

[0157] An opening into which an objective lens is fitted is provided at the tip of the endoscope 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 endoscope tube by a light guide extending inside the endoscope 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.

[0158] 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.

[0159] The CCU11201 consists of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and controls the operation of the endoscope 11100 and the display device 11202. It controls everything comprehensively. Furthermore, the CCU11201 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.

[0160] 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.

[0161] The light source device 11203 consists 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.

[0162] The input device 11204 is an input interface for the endoscopic surgical system 11000. The user can input various 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.

[0163] The treatment instrument control device 11205 controls the drive of the energy treatment instrument 11112 for purposes such as tissue cauterization, incision, or vascular sealing. The insufflation device 11206 delivers gas into the patient's body cavity via the insufflation tube 11111 to inflate the body cavity of the patient 11132 for the purpose of securing a field of view by the endoscope 11100 and securing the operator's working space. 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.

[0164] The light source device 11203, which 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 time-divisionally capture images corresponding to each of the RGB light sources by irradiating the observation target with laser light from each RGB laser light source 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.

[0165] 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.

[0166] 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, by utilizing the wavelength dependence of light absorption in body tissues and irradiating with narrow-band light compared to the irradiation light used during normal observation (i.e., white light), so-called narrow-band imaging is performed to capture images of predetermined tissues such as blood vessels on the surface of mucous membranes with high contrast. Alternatively, in special light observation, the excitation light is Fluorescence observation may be performed to obtain an image from the fluorescence generated by irradiation. In fluorescence observation, excitation light is irradiated onto body tissue and the fluorescence from the body tissue is observed (autofluorescence observation), or a reagent such as indocyanine green (ICG) is injected into body tissue and the body tissue is... By irradiating the reagent with excitation light corresponding to its fluorescence wavelength, a fluorescence image can be obtained. The light source device 11203 can be configured to supply narrowband light and / or excitation light suitable for such special light observations.

[0167] Figure 18 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in Figure 17.

[0168] 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 one another.

[0169] 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.

[0170] The imaging unit 11402 may consist of one image sensor (a so-called single-chip system) or multiple image sensors (a so-called multi-chip system). If the imaging unit 11402 is configured as a multi-chip system, for example, each image sensor may generate image signals corresponding to RGB, and these signals 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 system, multiple lens units 11401 may be provided corresponding to each image sensor.

[0171] Furthermore, the imaging unit 11402 does not necessarily have to be located in the camera head 11102. For example, the imaging unit 11402 may be located inside the lens barrel 11101, directly behind the objective lens.

[0172] 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.

[0173] The communication unit 11404 consists 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.

[0174] Furthermore, the communication unit 11404 receives control signals from the CCU 11201 to control the drive of the camera head 11102 and supplies them to the camera head control unit 11405. These control signals include information regarding 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.

[0175] 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 CCU11201 based on the acquired image signal. In the latter case, the endoscope 11100 will be equipped with so-called AE (Auto Exposure), AF (Auto Focus), and AWB (Auto White Balance) functions.

[0176] The camera head control unit 11405 controls the drive of the camera head 11102 based on the control signal received from the CCU 11201 via the communication unit 11404.

[0177] The communication unit 11411 consists 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.

[0178] 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.

[0179] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 11102.

[0180] 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 control signals to control the driving of the camera head 11102.

[0181] Furthermore, the control unit 11413 displays the captured image showing the surgical area 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 with confidence.

[0182] 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.

[0183] In the illustrated example, communication was performed via a wired connection using the transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may be performed wirelessly.

[0184] 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.

[0185] 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.

[0186] (Examples of applications 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 vehicle, such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, robots, construction machinery, or agricultural machinery (tractors).

[0187] Figure 19 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.

[0188] The vehicle control system 12000 comprises multiple electronic control units connected via a communication network 12001. In the example shown in Figure 19, 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] The imaging unit 12031 is an optical 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.

[0193] 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 images 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.

[0194] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking system based on information from 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 based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0195] 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.

[0196] 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.

[0197] 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 in Figure 19, the output devices are exemplified as 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.

[0198] Figure 20 shows an example of the installation position of the imaging unit 12031.

[0199] In Figure 20, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0200] 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.

[0201] Figure 20 shows an example of the imaging range 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.

[0202] 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.

[0203] For example, the microcomputer 12051, based on distance information obtained from 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 vehicle 12100). In particular, it can extract the nearest object on the vehicle 12100's path that is traveling in approximately the same direction as 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, where the vehicle drives autonomously without driver intervention, can be performed.

[0204] 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, heavy 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 display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010.

[0205] 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.

[0206] Although the present disclosure has been described above with reference to embodiments and modifications 1 to 5, as well as application examples and usage examples, this technology is not limited to the above embodiments, and various modifications are possible.

[0207] For example, in the above embodiment, an example was shown in which a single layer of light guide portion 24 is provided, having a plurality of structures 24A and a medium 24B provided around the plurality of structures 24A and having a refractive index different from that of the plurality of structures 24A. However, the invention is not limited to this, and multiple light guide portions may be stacked.

[0208] The light detection device disclosed herein only needs to receive incident light and convert the light into an electric charge. The output signal may be an image information signal or a distance measurement information signal. The light detection device can be applied to image sensors, distance measurement sensors, etc.

[0209] Furthermore, the light detection device according to this disclosure can also be used as a distance measuring sensor capable of measuring distance using the TOF (Time Of Flight) method. The light-receiving element (photoelectric conversion unit) of each pixel may be an APD (Avalanche Photo Diode). The light-receiving element may be composed of, for example, a SPAD (Single Photon Avalanche Diode). The light detection device can also be used as a sensor capable of detecting events, for example, an event-driven sensor (also called an EVS (Event Vision Sensor), EDS (Event Driven Sensor), DVS (Dynamic Vision Sensor), etc.).

[0210] Furthermore, the effects described herein are merely examples and are not limited to those described; other effects may also occur.

[0211] Furthermore, this disclosure can also take the following configuration. According to the technology with the following configuration, the light-receiving area of ​​the incident light in the photoelectric conversion unit is increased. Therefore, it becomes possible to miniaturize the pixels. (1) A semiconductor substrate having a first surface that serves as the light incident surface and a second surface opposite to the first surface, with a photoelectric conversion unit embedded and formed for each pixel, A first waveguide embedded in the semiconductor substrate and extending from the first surface toward the second surface, A light-gathering member disposed on the first surface side of the semiconductor substrate, which guides incident light to the first waveguide, A light detection device equipped with this device. (2) The photodetector according to (1), wherein the first waveguide is formed by including a material with a lower refractive index than the semiconductor substrate. (3) The pixels include a first pixel that detects light in a first wavelength band and a second pixel that detects light in a second wavelength band different from the first wavelength band. The photodetector according to (1) or (2), wherein the first waveguide is provided between adjacent first pixels and between adjacent second pixels, respectively. (4) The light detection device according to (3), wherein the first pixel and the second pixel have different areas from each other. (5) The photodetector according to any one of (1) to (4), further having separation grooves that extend from the first surface to the second surface of the semiconductor substrate and separate adjacent pixels. (6) The light detection device according to (5), wherein the side surface of the separation groove is covered with a light-reflective film. (7) The light detection device according to (6), wherein the light reflective film is formed by including a material having a reflectance of 90% or more with respect to the incident light. (8) The aforementioned pixel has a roughly rectangular shape with four sides in a plan view. The photodetector according to any one of (5) to (7), wherein the first waveguide is located on one of the four sides, and the separation grooves are provided on the three sides excluding the one side. (9) The photodetector according to any one of (5) to (8), wherein the first waveguide is arranged one or more inside the pixels separated from each other by the separation groove. (10) The semiconductor substrate further has an inner lens between it and the light-gathering member, The inner lens is positioned above the first waveguide, and the photodetector is as described in any one of (1) to (9). (11) The light-detecting device according to any one of (1) to (10), wherein the light-collecting member is a color splitter that changes the phase of the incident light to control the direction of light propagation. (12) The photodetector according to (11), wherein the color splitter comprises a plurality of structures, each having a size less than or equal to the wavelength of the incident light, and a medium provided to fill the space between adjacent plurality of structures, the medium having a refractive index different from that of the plurality of structures. (13) The photodetector according to any one of (1) to (12), wherein the first waveguide penetrates between the first surface and the second surface of the semiconductor substrate. (14) The photodetector according to any one of (1) to (13), wherein the first waveguide has an end inside the semiconductor substrate. (15) The photodetector according to any one of (1) to (14), further comprising a wiring layer on the second surface side of the semiconductor substrate. (16) The photodetector according to any one of (1) to (15), further comprising a multilayer wiring layer between the semiconductor substrate and the light-collecting member. (17) The system further includes a second waveguide that penetrates the aforementioned multilayer wiring layer, The light detection device according to (16), wherein the incident light is guided to the first waveguide via the second waveguide. (18) The second waveguide has a core layer and a cladding layer surrounding the core layer. The core layer is formed by comprising a material having a higher refractive index than the surrounding multilayer wiring layer. The photodetector according to (17), wherein the cladding layer is formed of a material having a lower refractive index than the surrounding multilayer wiring layer. (19) Equipped with a light detection device, The aforementioned light detection device is A semiconductor substrate having a first surface that serves as the light incident surface and a second surface opposite to the first surface, with a photoelectric conversion unit embedded and formed for each pixel, A first waveguide embedded in the semiconductor substrate and extending from the first surface toward the second surface, A light-gathering member disposed on the first surface side of the semiconductor substrate, which guides incident light to the first waveguide, A powerful electronic device. [Explanation of Symbols]

[0212] 1, 1A, 1B, 1C, 2... Light detection device, 10... Light receiving unit, 11... Semiconductor substrate, 12... Photoelectric conversion unit, 13... Separation groove, 14, 51... Waveguide, 15... Dielectric layer, 16... Low refractive index layer, 20... Optical layer, 21... Spacer layer, 22... Inner lens, 23... Planarization layer, 24... Light guide unit, 25... Anti-reflective film, 30, 50... Multilayer wiring layer, 51A... Core layer, 51B... Cladding layer, 100... Pixel unit, 1000... Electronic device.

Claims

1. A semiconductor substrate having a first surface that serves as the light incident surface and a second surface opposite to the first surface, with a photoelectric conversion unit embedded and formed for each pixel, A first waveguide embedded in the semiconductor substrate and extending from the first surface toward the second surface, A light-gathering member disposed on the first surface side of the semiconductor substrate, which guides incident light to the first waveguide, A light detection device equipped with this device.

2. The photodetector according to claim 1, wherein the first waveguide is formed by including a material with a lower refractive index than the semiconductor substrate.

3. The aforementioned pixels include a first pixel that detects light in a first wavelength band and a second pixel that detects light in a second wavelength band different from the first wavelength band. The photodetector according to claim 1, wherein the first waveguide is provided between adjacent first pixels and between adjacent second pixels, respectively.

4. The photodetector according to claim 3, wherein the first pixel and the second pixel have different areas from each other.

5. The photodetector according to claim 1, further comprising separation grooves that extend from the first surface to the second surface of the semiconductor substrate and separate adjacent pixels.

6. The light detection device according to claim 5, wherein the side surface of the separation groove is covered with a light-reflective film.

7. The light detection device according to claim 6, wherein the light-reflecting film is formed by including a material having a reflectance of 90% or more with respect to the incident light.

8. The aforementioned pixel has a roughly quadrilateral shape with four sides in a plan view. The photodetector according to claim 5, wherein the first waveguide is located on one of the four sides, and the separation grooves are provided on the three sides excluding the one side.

9. The photodetector according to claim 5, wherein the first waveguide is arranged in one or more locations inside the pixels separated from each other by the separation grooves.

10. The semiconductor substrate further has an inner lens between it and the light-gathering member, The light detection device according to claim 1, wherein the inner lens is positioned above the first waveguide.

11. The light detection device according to claim 1, wherein the light-collecting member is a color splitter that changes the phase of the incident light to control the direction of light propagation.

12. The photodetector according to claim 11, wherein the color splitter comprises a plurality of structures, each having a size less than or equal to the wavelength of the incident light, and a medium provided to fill the space between adjacent plurality of structures, the medium having a refractive index different from that of the plurality of structures.

13. The photodetector according to claim 1, wherein the first waveguide penetrates between the first surface and the second surface of the semiconductor substrate.

14. The photodetector according to claim 1, wherein the first waveguide has an end inside the semiconductor substrate.

15. The photodetector according to claim 1, further comprising a wiring layer on the second surface side of the semiconductor substrate.

16. The photodetector according to claim 1, further comprising a multilayer wiring layer between the semiconductor substrate and the light-collecting member.

17. The system further comprises a second waveguide penetrating the aforementioned multilayer wiring layer, The light detection device according to claim 16, wherein the incident light is guided to the first waveguide via the second waveguide.

18. The second waveguide has a core layer and a cladding layer surrounding the core layer. The core layer is formed by comprising a material having a higher refractive index than the surrounding multilayer wiring layer. The photodetector according to claim 17, wherein the cladding layer is formed of a material having a lower refractive index than the surrounding multilayer wiring layer.

19. Equipped with a light detection device, The aforementioned light detection device is A semiconductor substrate having a first surface that serves as the light incident surface and a second surface opposite to the first surface, with a photoelectric conversion unit embedded and formed for each pixel, A first waveguide embedded in the semiconductor substrate and extending from the first surface toward the second surface, A light-gathering member disposed on the first surface side of the semiconductor substrate, which guides incident light to the first waveguide, A powerful electronic device.

Images