Patent Publication Number: US-2023143614-A1

Title: Solid-state imaging device and electronic apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 16/959,709, filed on Jul. 2, 2020, which is a U.S. National Phase of International Patent Application No. PCT/JP2018/048418 filed on Dec. 28, 2018, which claims priority benefit of Japanese Patent Application No. JP 2018-002367 filed in the Japan Patent Office on Jan. 11, 2018. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present technology relates to a solid-state imaging device and an electronic apparatus, and, for example, to a solid-state imaging device and an electronic apparatus capable of improving sensitivity while suppressing deterioration of color mixing. 
     BACKGROUND ART 
     In a solid-state imaging device, as a structure for preventing reflection of incident light, it has been proposed to provide a fine concave-convex structure at an interface on a light receiving surface side of a silicon layer on which a photodiode is formed (for example, Patent Documents 1 and 2). 
     CITATION LIST 
     Patent Document 
     Patent Document 1: Japanese Patent Application Laid-Open No. 2010-272612 
     Patent Document 2: Japanese Patent Application Laid-Open No. 2013-33864 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, the fine concave-convex structure can improve sensitivity by preventing the reflection of incident light, but scattering becomes also large and an amount of light leaking into adjacent pixels is increased, and thus, there has been a possibility that color mixing would be deteriorated. 
     The present disclosure has been made in view of such a situation, and an object of the present disclosure is to improve sensitivity while suppressing deterioration of color mixing. 
     Solutions to Problems 
     A solid-state imaging device according to an aspect o the present technology includes: a substrate; a first photoelectric conversion region that is provided in the substrate; a second photoelectric conversion region that is provided in the substrate; a trench that is provided between the first photoelectric conversion region and the second photoelectric conversion region and penetrates through the substrate; a first concave portion region that has a plurality of concave portions provided on a light receiving surface side of the substrate, above the first photoelectric conversion region; and a second concave portion region that has a plurality of concave portions provided on the light receiving surface side of the substrate, above the second photoelectric conversion region. 
     An electronic apparatus according to an aspect of the present technology includes the solid-state imaging device described above. 
     The solid-state imaging device according to an aspect of the present technology includes the first photoelectric conversion region and the second photoelectric conversion region provided in the substrate, the trench provided between the first photoelectric conversion region and the second photoelectric conversion region and penetrating through the substrate, the first concave portion region having the plurality of concave portions provided on the light receiving surface side of the substrate, above the first photoelectric conversion region, and the second concave portion region having the plurality of concave portions provided on the light receiving surface side of the substrate, above the second photoelectric conversion region. 
     The electronic apparatus according to an aspect of the present technology includes the solid-state imaging device described above. 
     Note that the solid-state imaging device and the electronic apparatus may be independent devices or may be internal blocks configuring one device. 
     Effects of the Invention 
     According to the embodiments of the present technology, it is possible to improve sensitivity while suppressing deterioration of color mixing. 
     Note that an effect described here is not necessarily limited, and may be any effect described in the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a diagram illustrating a schematic configuration of a solid-state imaging device according to the present disclosure. 
         FIG.  2    is a diagram illustrating a cross-sectional configuration example of a pixel according to a first embodiment. 
         FIG.  3    is a diagram for describing a concave portion region. 
         FIG.  4    is a diagram for describing a concave portion region. 
         FIG.  5    is a diagram illustrating a cross-sectional configuration example of a pixel according to a second embodiment. 
         FIGS.  6 A and  6 B  are diagrams for describing an effect of a pixel structure of the present disclosure. 
         FIG.  7    is a diagram for describing optimal conditions at various places of a pixel. 
         FIG.  8    is a diagram illustrating a cross-sectional configuration example of a pixel according to a third embodiment. 
         FIG.  9    is a diagram illustrating a cross-sectional configuration example of a pixel according to a fourth embodiment. 
         FIG.  10    is a diagram illustrating another cross-sectional configuration example of a pixel according to the fourth embodiment. 
         FIG.  11    is a diagram illustrating a cross-sectional configuration example of a pixel according to a fifth embodiment. 
         FIG.  12    is a diagram illustrating a cross-sectional configuration example of a pixel according to a sixth embodiment. 
         FIG.  13    is a diagram illustrating a cross-sectional configuration example of a pixel according to a seventh embodiment. 
         FIG.  14    is a diagram illustrating a cross-sectional configuration example of a pixel according to an eighth embodiment. 
         FIG.  15    is a diagram illustrating a cross-sectional configuration example of a pixel according to a ninth embodiment. 
         FIG.  16    is a diagram illustrating a cross-sectional configuration example of a pixel according to a tenth embodiment. 
         FIG.  17    is a diagram illustrating a cross-sectional configuration example of a pixel according to an eleventh embodiment. 
         FIG.  18    is a diagram illustrating a cross-sectional configuration example of a pixel according to a twelfth embodiment. 
         FIG.  19    is a diagram illustrating a cross-sectional configuration example of a pixel according to a thirteenth embodiment. 
         FIG.  20    is a block diagram illustrating a configuration example of an imaging device as an electronic apparatus according to the present disclosure. 
         FIG.  21    is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. 
         FIG.  22    is a block diagram illustrating an example of functional configurations of a camera head and a camera control unit (CCU). 
         FIG.  23    is a block diagram illustrating an example of a schematic configuration of a vehicle control system. 
         FIG.  24    is an explanatory diagram illustrating an example of installation positions of an outside-vehicle information detection unit and an imaging unit. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, modes (hereinafter, referred to as embodiments) for carrying out the present technology will be described. 
     &lt;Schematic Configuration Example of Solid-State Imaging Device&gt; 
       FIG.  1    illustrates a schematic configuration of a solid-state imaging device according to the present disclosure. 
     The solid-state imaging device  1  of  FIG.  1    includes a pixel array unit  3  in which pixels  2  are arranged in a two-dimensional array shape and a peripheral circuit unit arranged around the pixel array unit  3 , on a semiconductor substrate  12  using, for example, silicon (Si) as a semiconductor. The peripheral circuit unit includes a vertical drive circuit  4 , column signal processing circuits  5 , a horizontal drive circuit  6 , an output circuit  7 , a control circuit  8 , and the like. 
     The pixel  2  includes a photodiode as a photoelectric conversion element and a plurality of pixel transistors. The plurality of pixel transistors includes, for example, four metal oxide semiconductor (MOS) transistors, that is, a transfer transistor, a selection transistor, a reset transistor, and an amplification transistor. 
     Furthermore, the pixel  2  can also have a shared pixel structure. This shared pixel structure includes a plurality of photodiodes, a plurality of transfer transistors, one shared floating diffusion region, and one other pixel transistor that is shared. That is, in a shared pixel, photodiodes and transfer transistors that configure a plurality of unit pixels are configured to share one other pixel transistor with each other. 
     The control circuit  8  receives an input clock and data instructing an operation mode and the like, and outputs data such as internal information of the solid-state imaging device  1 . That is, the control circuit  8  generates a clock signal or a control signal which is a reference for operations of the vertical drive circuit  4 , the column signal processing circuits  5 , the horizontal drive circuit  6 , and the like, on the basis of a vertical synchronization signal, a horizontal synchronization signal, and a master clock. Then, the control circuit  8  outputs the generated clock signal or control signal to the vertical drive circuit  4 , the column signal processing circuits  5 , the horizontal drive circuit  6 , and the like. 
     The vertical drive circuit  4  is configured by, for example, a shift register, selects pixel drive wirings  10 , supplies pulses for driving the pixels  2  to the selected pixel drive wirings  10 , and drives the pixels  2  in row units. That is, the vertical drive circuit  4  selectively scans each pixel  2  of the pixel array unit  3  sequentially in the vertical direction in row units, and supplies pixel signals based on signal charges generated according to amounts of received light in a photoelectric conversion unit of each pixel  2  to the column signal processing circuits  5  through vertical signal lines  9 . 
     The column signal processing circuit  5  is arranged for every column of the pixels  2 , and performs signal processing such as noise removal on signals output from the pixels  2  of one row for every pixel column. For example, the column signal processing circuit  5  performs signal processing such as correlated double sampling (CDS) processing, and analog-to-digital (AD) conversion processing, for removing fixed pattern noise unique to the pixels. 
     The horizontal drive circuit  6  is configured by, for example, a shift register, sequentially selects each of the column signal processing circuits  5  by sequentially outputting horizontal scanning pulses, and outputs pixel signals from each of the column signal processing circuits  5  to a horizontal signal line  11 . 
     The output circuit  7  performs signal processing on the signals sequentially supplied from each of the column signal processing circuits  5  through the horizontal signal line  11 , and outputs the processed signals. For example, the output circuit  7  may perform only buffering or may perform black level adjustment, column variation correction, various digital signal processing, and the like. An input/output terminal  13  exchanges signals with the outside. 
     The solid-state imaging device  1  configured as described above is a CMOS image sensor called a column AD manner in which the column signal processing circuit  5  performing the CDS processing and the AD conversion processing is arranged for every pixel column. 
     Furthermore, the solid-state imaging device  1  is a backside illumination MOS solid-state imaging device in which light is incident from a back surface side opposite to a front surface side of the semiconductor substrate  12  on which the pixel transistors are formed. 
     Pixel Structure According to First Embodiment 
       FIG.  2    is a diagram illustrating a cross-sectional configuration example of a pixel  2   a  according to a first embodiment. 
     The solid-state imaging device  1  includes the semiconductor substrate  12  and a multilayer wiring layer  21  and a support substrate  22  formed on a front surface side (a lower side in the drawing) of the semiconductor substrate  12 . 
     The semiconductor substrate  12  includes, for example, silicon (Si) and is formed to have a thickness of, for example, 1 to 6 μm. In the semiconductor substrate  12 , for example, an N-type (second conductivity-type) semiconductor region  42  is formed for every pixel  2   a  in a P-type (first conductivity-type) semiconductor region  41 , such that a photodiode PD is formed in pixel units. The P-type semiconductor regions  41  provided on front and back surfaces of the semiconductor substrate  12  also serve as hole charge accumulation regions for suppressing a dark current. 
     Note that at a pixel boundary of each pixel  2   a  between the N-type semiconductor regions  42 , the P-type semiconductor region  41  is dug in a state where it penetrates through the semiconductor substrate  12 , as illustrated in  FIG.  2   , in order to form an inter-pixel light shielding portion  47  as described later. 
     An interface (interface on a light receiving surface side) of the P-type semiconductor region  41  above the N-type semiconductor region  42  which is a charge accumulation region is configured to prevent reflection of incident light by a concave portion region  48  forming a fine concave-convex structure. The concave portion region  48  will be further described with reference to  FIGS.  3  and  4   . 
     The multilayer wiring layer  21  includes a plurality of wiring layers  43  and an interlayer insulating film  44 . Furthermore, in the multilayer wiring layer  21 , a plurality of pixel transistors Tr for performing readout and the like of charges accumulated in the photodiodes PD are also formed. 
     On a back surface side of the semiconductor substrate  12 , a pinning layer  45  is formed so as to cover an upper surface of the P-type semiconductor region  41 . The pinning layer  45  is formed using a high dielectric having a negative fixed charge so that a positive charge (hole) accumulation region is formed at an interface portion with the semiconductor substrate  12  to suppress generation of a dark current. By forming the pinning layer  45  so as to have the negative fixed charge, an electric field is applied to an interface with the semiconductor substrate  12  by the negative fixed charge, and the positive charge accumulation region is thus formed. 
     As the pinning layer  45 , a Si cover film (SCF) can be used. Furthermore, the pinning layer  45  is formed using, for example, hafnium oxide (HfO 2 ). Furthermore, the pinning layer  45  may be formed using zirconium dioxide (ZrO 2 ), tantalum oxide (Ta 2 O 5 ), or the like. 
     A transparent insulating film  46  is embedded in a penetration portion of the P-type semiconductor region  41 , and is formed on the entire back surface side above the pinning layer  45  of the semiconductor substrate  12 . The penetration portion of the P-type semiconductor region  41  in which the transparent insulating film  46  is embedded configures an inter-pixel light shielding portion  47  preventing leakage of incident light from adjacent pixels  2   a.    
     The transparent insulating film  46  includes a material that transmits light, has an insulating property, and has a refractive index n 1  smaller than a refractive index n 2  of the semiconductor regions  41  and  42  (n 1 &lt;n 2 ). As the material of the transparent insulating film  46 , silicon oxide (SiO 2 ), silicon nitride (SiN), silicon oxynitride (SiON), hafnium oxide (HfO 2 ), aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO 2 ), tantalum oxide (Ta 2 O 5 ), titanium oxide (TiO 2 ), lanthanum oxide (La 2 O 3 ), praseodymium oxide (Pr 2 O 3 ), cerium oxide (CeO 2 ), neodymium oxide (Nd 2 O 3 ), promethium oxide (Pm 2 O 3 ), samarium oxide (Sm 2 O 3 ), europium oxide (Eu 2 O 3 ), gadolinium oxide (Gd 2 O 3 ), terbium oxide (Tb 2 O 3 ), dysprosium oxide (Dy 2 O 3 ), holmium oxide (Ho 2 O 3 ), thulium oxide (Tm 2 O 3 ), ytterbium oxide (Yb 2 O 3 ), lutetium oxide (Lu 2 O 3 ), yttrium oxide (Y 2 O 3 ), a resin, or the like, can be used alone or in combination. 
     Note that an antireflection film may be stacked on the pinning layer  45  before forming the transparent insulating film  46 . As a material of the antireflection film, silicon nitride (SiN), hafnium oxide (HfO 2 ), aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO 2 ), tantalum oxide (Ta 2 Ta 5 ), titanium oxide (TiO 2 ), lanthanum oxide (La 2 O 3 ), praseodymium oxide (Pr 2 O 3 ), cerium oxide (CeO 2 ), neodymium oxide (Nd 2 O 3 ), promethium oxide (Pm 2 O 3 ), samarium oxide (Sm 2 O 3 ), europium oxide (Eu 2 O 3 ), gadolinium oxide (Gd 2 O 3 ), terbium oxide (Tb 2 O 3 ), dysprosium oxide (Dy 2 O 3 ), holmium oxide (Ho 2 O 3 ), thulium oxide (Tm 2 O 3 ), ytterbium oxide (Yb 2 O 3 ), lutetium oxide (Lu 2 O 3 ), yttrium oxide (Y 2 O 3 ), or the like, can be used. 
     The antireflection film may be formed only on an upper surface of the concave portion region  48  or may be formed on both of the upper surface of the concave portion region  48  and a side surface of the inter-pixel light shielding portion  47 , similar to the pinning layer  45 . 
     A light shielding film  49  is formed in a region of the pixel boundary on the transparent insulating film  46 . A material of the light shielding film  49  may be any material that shields light, and for example, tungsten (W), aluminum (Al), copper (Cu), or the like can be used as the material of the light shielding film  49 . 
     A flattening film  50  is formed on the entire upper surface of the transparent insulating film  46  as well as the light shielding film  49 . As a material of the flattening film  50 , for example, an organic material such as a resin can be used. 
     On the flattening film  50 , a color filter layer  51  of red, green, or blue is formed for every pixel. The color filter layer  51  is formed, for example, by spin-coating a photosensitive resin containing a coloring matter such as a pigment or a dye. Each color of red, green, and blue is arranged, for example, in a Bayer array, but may be arranged in another array manner. In the example of  FIG.  2   , a color filter layer  51  of blue (B) is formed in a right pixel  2   a,  and a color filter layer  51  of green (G) is formed in a left pixel  2   a.    
     On the color filter layer  51 , an on-chip lens  52  is formed for every pixel  2   a.  The on-chip lens  52  includes, for example, a resin-based material such as a styrene resin, an acrylic resin, a styrene-acryl copolymer resin, or a siloxane resin. The incident light is condensed by the on-chip lens  52 , and the condensed light is efficiently incident on the photodiode PD via the color filter layer  51 . 
     Each pixel  2   a  of the pixel array unit  3  of the solid-state imaging device  1  is configured as described above. 
     Here, the concave portion region  48  will be described with reference to  FIG.  3   . The concave portion region  48  is a region in which fine concave-convex portions are formed, and the concave portion and the convex portion are different from each other depending on where a surface which is a reference (hereinafter referred to as a reference surface) is located. 
     Furthermore, the concave portion region  48  is a region having a fine concave-convex structure formed at the interface (interface on the light receiving surface side) of the P-type semiconductor region  41  above the N-type semiconductor region  42  which is the charge accumulation region. This concave-convex structure is formed on a light receiving surface side of the semiconductor region  42 , in other words, the semiconductor substrate  12 . Therefore, a predetermined surface of the semiconductor substrate  12  can be used as the reference surface, and here, a description will be continued by taking a case where a part of the semiconductor substrate  12  is used as the reference surface as an example. 
       FIG.  3    is an enlarged view of the vicinity of the concave portion region  48 . A surface of the concave portion region  48  which is a boundary portion between the concave portion region  48  and the pinning layer  45  and is close to the transparent insulating film  46  is referred to as an upper surface  48 - 1 . Furthermore, a surface of the concave portion region  48  which is a boundary portion between the concave portion region  48  and the pinning layer  45  and is close to the semiconductor region  42  is referred to as a lower surface  48 - 2 . 
     Furthermore, it is assumed that a reference surface A is a surface at a position where the upper surface  48 - 1  is formed, and it is assumed that a reference surface C is a surface at a position where the lower surface  48 - 2  is formed. It is assumed that a reference surface B is a surface that is at a position between the reference surface A and the reference surface C, in other words, a surface that is at a position between the upper surface  48 - 1  and the lower surface  48 - 2 . 
     In a case where the reference surface A is used as a reference, a shape of the concave portion region  48  is a shape in which concave portions are present with respect to the reference surface A. That is, in a case where the reference surface A is used as the reference, the lower surface  48 - 2  is located at a position depressed downward with respect to the reference surface A (=the upper surface  48 - 1 ), such that the concave portion region  48  becomes a region in which fine concave portions are formed. Moreover, in other words, when the reference surface A is used as the reference, the concave portion region  48  can be said to be a region in which the concave portion is formed between the upper surface  48 - 1  and the upper surface  48 - 1 , such that fine concave portions are formed. 
     In a case where the reference surface C is used as a reference, a shape of the concave portion region  48  is a shape in which convex portions are present with respect to the reference surface C. That is, in a case where the reference surface C is used as the reference, the upper surface  48 - 1  is located at a position projecting upward with respect to the reference surface C (=the lower surface  48 - 2 ), such that the concave portion region  48  becomes a region in which fine convex portions are formed. Moreover, in other words, when the reference surface C is used as the reference, the concave portion region  48  can be said to be a region in which the convex portion is formed between the lower surface  48 - 2  and the lower surface  48 - 2 , such that fine convex portions are formed. 
     In a case where the reference surface B is used as a reference, a shape of the concave portion region  48  is a shape in which concave portions and convex portions are present with respect to the reference surface B. That is, in a case where the reference surface B is used as the reference, the lower surface  48 - 2  is located at a position depressed downward with respect to the reference surface B (=the surface that is at the position between the upper surface  48 - 1  and the lower surface  48 - 2 ), such that the concave portion region  48  can be said to be a region in which fine concave portions are formed. 
     Furthermore, in a case where the reference surface B is used as the reference, the upper surface  48 - 1  is located at a position projecting upward with respect to the reference surface B, such that the concave portion region  48  can be said to be a region in which fine convex portions are formed. 
     As described above, the concave portion region  48  is a region that can be expressed as a region formed by the fine concave portions, a region formed by the fine convex portions, or a region formed by the fine concave portions and convex portions, depending on where the reference surface is set, in cross-sectional view of the pixel  1 . 
     In the following description, the concave portion region  48  will be described by taking a case where the reference surface A, that is, the upper surface  48 - 1  is used as the reference surface as an example, and a description will be continued on the assumption that the concave portion region  48  is a region in which the fine concave portions are formed. 
     In the concave portion region  48 , a pitch between the concave portions corresponding to a period of the concave portions is set to, for example, 250 nm or more. 
     In an example illustrated in  FIG.  3   , a case where the concave portion region  48  has a shape in which planes of the upper surface  48 - 1  and the lower surface  48 - 2  are combined with each other has been illustrated as an example, but a concave portion region  48  having a shape as illustrated in  FIG.  4    is also included in the concave portion region  48  to which the present technology is applied. 
     The concave portion region  48  illustrated in  FIG.  4    is formed in a triangular shape in cross-sectional view. Even though a shape of the concave portion region  48  is such a shape, a reference surface can be set, and concave portions or convex portions can be defined on the basis of the reference surface. 
     Since the concave portion region  48  illustrated in  FIG.  4    is formed in the triangular shape in cross-sectional view, as an example of the reference surface, a surface connecting vertices to each other is set to be the reference surface. 
     In cross-sectional view, a surface including a line connecting vertices close to the transparent insulating film  46  among the vertices of the triangular shape of the concave portion region  48  to each other is defined as a reference surface A. A surface including a line connecting vertices close to a bottom side, in other words, vertices close to the semiconductor region  42 , among the vertices of the triangular shape of the concave portion region  48  to each other is defined as a reference surface C. A surface between the reference surface A and the reference surface C is defined as a reference surface B. 
     Even in a case where the reference surface is set at a position of the vertex of the triangular shape of the concave portion region  48  as described above, a shape of the concave portion region  48  can be expressed differently depending on where the reference surface is located, similar to a case described with reference to  FIG.  3   . 
     That is, in a case where the reference surface A is used as a reference, a shape of the concave portion region  48  is a shape in which downward triangular (valley-shaped) concave portions are present with respect to the reference surface A. That is, in a case where the reference surface A is used as the reference, a valley region is located below the reference surface A and corresponds to the concave portion. Therefore, the concave portion region  48  becomes a region in which fine concave portions are formed. Moreover, in other words, when the reference surface A is used as the reference, the concave portion region  48  can be said to be a region in which the concave portion is formed between a vertex of a triangle and a vertex of an adjacent triangle, such that fine concave portions are formed. 
     In a case where the reference surface C is used as a reference, a shape of the concave portion region  48  is a shape in which upward triangular (peak-shaped) convex portions are present with respect to the reference surface C. That is, in a case where the reference surface C is used as the reference, a peak region is located above the reference surface C and corresponds to the convex portion. Therefore, the concave portion region  48  becomes a region in which fine convex portions are formed. Moreover, in other words, when the reference surface C is used as the reference, the concave portion region  48  can be said to be a region in which the convex portion is formed between vertices of a bottom side of the triangular shape, such that fine head portions are formed. 
     In a case where the reference surface B is used as a reference, a shape of the concave portion region  48  is a shape in which concave portions and convex portions (valleys and peaks) are present with respect to the reference surface B. That is, in a case where the reference surface B is used as the reference, the concave portions that become the valleys are present below the reference surface B and the convex portions that become the peaks are present above the reference surface B. Therefore, the concave portion region  48  can be said to be a region including fine concave portions and convex portions. 
     As described above, even though a shape of the concave portion region  48  is a zigzag shape in which the peaks and the valleys are present as illustrated in  FIG.  4   , the concave portion region  48  can be defined to be a region that can be expressed as a region formed by the fine concave portions, a region formed by the fine convex portions, or a region formed by the fine concave portions and convex portions, depending on where the reference surface is set, in cross-sectional view of the pixel  1 . 
     Furthermore, in the concave portion region  48  illustrated in  FIG.  3    or  FIG.  4   , for example, in a case where the reference surface is an interface between the flattening film  50  and the transparent insulating film  46 , the concave portion region  48  has a shape in which regions (valleys) having a depression are present, and can thus be said to be a region formed by the fine concave portions. 
     Furthermore, in a case where the reference surface is an interface between the P-type semiconductor region  41  and the N-type semiconductor region  42 , the concave portion region  48  has a shape in which projecting regions (peaks) are present, and can thus be said to be a region formed by the fine convex portions. 
     As described above, in cross-sectional view of the pixel  2 , a predetermined flat surface is used as the reference surface, and a shape of the concave portion region  48  can also be expressed depending on whether portions having a valley shape with respect to the reference surface are formed or portions having a peak shape with respect to the reference surface are formed. 
     Moreover, as will be described later with reference to  FIG.  11   , a configuration in which a flat portion  53  is formed between the pixels  2  can also be adopted. The flat portion  53  is a region provided by providing a region of a predetermined width in which the concave portion region  48  is not formed between the pixels  2   e  at an interface on the light receiving surface side of the semiconductor substrate  12 . A surface including the flat portion  53  may be used as the reference surface. 
     Referring to  FIG.  11   , in case where the surface including the flat portion  53  is used as the reference surface, the concave portion region  48  can be said to have a shape having portions depressed downward with respect to the reference surface, in other words, valley-shaped portions, and can thus be said to be a region in which fine concave portions are formed. 
     As described above, the concave portion region  48  is a region that can be expressed as a region formed by the fine concave portions, a region formed by the fine convex portions, or a region formed by the fine concave portions and convex portions, depending on where the reference surface is set, in cross-sectional view of the pixel  1 . 
     Moreover, the concave portion region  48  can be expressed as forming the region formed by the fine concave portions, forming the region formed by the fine convex portions, or forming the region formed by the fine concave portions, depending on a method of forming the concave portion region  48 . 
     For example, in a case where the concave portion region  48  illustrated in  FIG.  3    is formed, that is, in a case where the concave portion region  48  having a shape in which the upper surface  48 - 1  is formed to be larger than the lower surface  48 - 2  is formed, it can be said that a portion that becomes the concave portion is formed and it can be said that a portion that becomes the convex portion is left, by shaving the substrate (semiconductor substrate  12 ). 
     In a case where a shaving amount of the substrate exceeds 50%, an area of the concave portion is formed to be larger than that of the convex portion, such that an amount of the shaved substrate (silicon) becomes a state where it is larger than that of the remaining substrate. In other words, a case of such a method of forming the concave portion region is formation in a situation where the concave portion is dominant, and it can be expressed that the concave portion region  48  is formed by providing a plurality of convex portions. 
     Furthermore, in a case where a shaving amount of the substrate is 50% or less, an area of the concave portion is formed to be smaller than that of the convex portion, such that an amount of the shaved substrate (silicon) becomes a state where it is smaller than that of the remaining substrate. In other words, a case of such a method of forming the concave portion region is formation in a situation where the convex portion is dominant, and it can be expressed that the concave portion region  48  is formed by providing a plurality of concave portions. 
     Consequently, according to the method of forming the concave portion region  48 , in a case where the concave portion becomes dominant, it can be expressed that the plurality of convex portions is provided and in a case where the substrate becomes dominant, it can be expressed that the plurality of concave portions is provided. 
     As described above, depending on the method of forming a concave portion region  48 , the concave portion region  48  is a region that can be expressed as a region formed by the fine concave portions, a region formed by the fine convex portions, or a region formed by the fine concave portions and convex portions, in cross-sectional view of the pixel  1 . 
     In the following description, a description will be continued on the assumption that the concave portion region  48  is the region formed by the fine concave portions, but the concave portion region  48  is an expression including a region such as the region formed by the fine convex portions or the region formed by the fine concave portions and convex portions, as described above. 
     Pixel Structure According to Second Embodiment 
       FIG.  5    is a diagram illustrating a cross-sectional configuration example of a pixel  2   b  according to a second embodiment. 
     The cross-sectional configuration example of the pixel  2   b  illustrated in  FIG.  5    has a configuration in which the color filter layer  51  is removed from the configuration of the pixel  2   a  according to the first embodiment illustrated in  FIG.  2   . The present technology can also be applied to the pixel  2   b  having a structure in which the color filter layer  51  is not present. 
     The pixel  2   b  according to the second embodiment can be applied to, for example, a pixel receiving infrared light (IR). As described later, according to the pixel  2   b  to which the present technology is applied, an optical path length can be increased, and it becomes thus possible to improve sensitivity without increasing a thickness of the pixel  2   b,  in other words, a thickness of a semiconductor substrate  12 , even in the infrared light having a long wavelength. 
     &lt;Effect of Pixel Structures According to First and Second Embodiments&gt; 
       FIGS.  6 A and  6 B  are diagrams for describing an effect of a pixel structure of the pixel  2   a  illustrated in  FIG.  2   . Since a similar effect can also be obtained in the pixel  2   b  illustrated in  FIG.  5   , here, a description will be continued by taking the pixel structure of the pixel  2   a  illustrated in  FIG.  2    as an example. Furthermore, an effect described here is an effect similarly obtained in an embodiment as described later. 
       FIG.  6 A  is a diagram for describing an effect by the concave portion region  48 . 
     Reflection of incident light is prevented by the concave portion region  48 . Therefore, sensitivity of the solid-state imaging device  1  can be improved. 
       FIG.  6 B  is a diagram for describing an effect by an inter-pixel light shielding portion  47  having a trench structure. 
     Conventionally, in a case where the inter-pixel light shielding portion  47  is not provided, incident light scattered by the concave portion region  48  might pass through a photoelectric conversion region (semiconductor regions  41  and  42 ). The inter-pixel light shielding portion  47  has an effect of reflecting the incident light scattered by the concave portion region  48  to confine the incident light in the photoelectric conversion region. Therefore, an optical distance for absorbing silicon is extended, and sensitivity can thus be improved. 
     Furthermore, since the inter-pixel light shielding portion  47  is dug in a state where it penetrates through the semiconductor substrate  12 , in other words, in a state where it reaches the multilayer wiring layer  21 , the inter-pixel light shielding portion  47  has an effect of more certainly confining the incident light in the photoelectric conversion region. Moreover, although there is also incident light reflected by the multilayer wiring layer  21 , the incident light reflected by the multilayer wiring layer  21  can also be confined in the photoelectric conversion region, such that the sensitivity can be further improved. 
     Assuming that a refractive index (n 1 ) of the inter-pixel light shielding portion  47  is 1.5 (corresponding to SiO 2 ) and a refractive index (n 2 ) of the semiconductor region  41  in which the photoelectric conversion region is formed is 4.0, a waveguide effect (photoelectric conversion region: core, inter-pixel light shielding portion  47 : clad) occurs due to the a difference (n 1 &lt;n 2 ) between the refractive indices, and the incident light is thus confined in the photoelectric conversion region. The concave portion region  48  has a disadvantage of deteriorating color mixing due to light scattering, but can counteract the deterioration of the color mixing by combining with the inter-pixel light shielding portion  47 , and further has an advantage of improving photoelectric conversion efficiency by increasing an incident angle of the incident light traveling in the photoelectric conversion region. 
     Furthermore, since it becomes possible to extend the optical distance for absorbing silicon, a structure of increasing the optical path length can be obtained as described above. Therefore, it becomes possible to efficiently condense even incident light having a long wavelength on the photodiode PD, such that it becomes possible to improve sensitivity even for the incident light having the long wavelength. 
     &lt;Optimal Condition Example of Pixel Structure&gt; 
     Optimal conditions at various places of the pixel  2   a  will be described with reference to  FIG.  7   . 
     In the embodiment described above, the concave portion region  48  has been formed in the entire region on the light receiving surface side of the semiconductor regions  41  and  42  in which the photodiode PD is formed. 
     However, a concave portion arrangement region L 1  (concave portion arrangement width L 1 ) of the concave portion region  48  can be formed only at a pixel central portion in a region of a predetermined ratio to a pixel region L 4  (pixel width L 4 ), as illustrated in  FIG.  7   . Then, it is desirable that the concave portion arrangement region L 1  of the concave portion region  48  is a region of approximately 80% of the pixel region L 4 . 
     The light condensed by the on-chip lens  52  is focused on the center of a region of a sensor (photodiode PD), which is the photoelectric conversion region. Therefore, the closer to the center of the sensor, the stronger the light intensity, and the more distant from the center of the sensor, the weaker the light intensity In a region distant from the center of the sensor, there are many diffracted light noise components, that is, color mixture noise components to adjacent pixels. 
     Therefore, a concave portion structure is not formed in the vicinity of the inter-pixel light shielding portion  47 , such that light scattering can be suppressed and noise can be suppressed. The concave portion arrangement region L 1  of the concave portion region  48  is changed depending on a difference in an upper layer structure such as a pixel size, a curvature of the on-chip lens, and a total thickness of the pixel  2   a,  but it is desirable that the on-chip lens  52  is generally a region of approximately 80% of the pixel region L 4  in order to condense spot light on a region of 80% of the center of the region of the sensor. 
     Furthermore, a size (convex portion formed between the concave portions) of the concave portion of the concave portion region  48  can be formed to be different for every color. As a size of the convex portion (a size from the bottom side to the vertex of the concave portion), a height, an arrangement area (an area in which the convex portion is formed in plan view), and a pitch can be defined. 
     Here, a description will be provided using the convex portion on the assumption that a depth of the concave portion is equal to the height of the convex portion and the convex portion is a portion of the upper surface  48 - 1  based on the reference surface C as described with reference to  FIG.  3   . 
     The height of the convex portion becomes lower as a wavelength of the incident light becomes shorter. That is, assuming that a height of a convex portion of a red pixel  2   a  is hR, a height of a convex portion of a green pixel  2   a  is hG, and a height of a convex portion of a blue pixel  2   a  is hB, the concave portion regions  48  can be formed so that a magnitude relation of 
         h R&gt; h G&gt; h B 
     is established. 
     Furthermore, the arrangement area of the convex portion becomes smaller as the wavelength of the incident light becomes shorter. That is, assuming that an arrangement area of the convex portion of the red pixel  2   a  is xR, an arrangement area of the convex portion of the green pixel  2   a  is xG, and an arrangement area of the convex portion of the blue pixel  2   a  is xB, the concave portion regions  48  can be formed so that a magnitude relation of xR&gt;xG&gt;xB is established. A width of the arrangement area in one direction corresponds to the concave portion arrangement width L 1  in  FIG.  7   . 
     The pitch between the convex portions becomes lower as the wavelength of the incident light becomes shorter. That is, assuming that a pitch between the convex portions of the red pixel  2   a  is pR, a pitch between the convex portions of the green pixel  2   a  is pG, and a pitch between the convex portion of the blue pixel  2   a  is pB, the concave portion regions  48  can be formed so that a magnitude relation of 
         p R&gt; p G&gt; p B 
     is established. 
     Furthermore, the pitch between the convex portions can be set to be a divisor of a pixel pitch between two-dimensionally arranged pixels, in other words, a pitch between the pixels  2  of the pixel array unit  3  (see  FIG.  1   ). 
     The concave portion region  48  satisfying such conditions can be formed by, for example, wet etching using a resist pattern as a mask. 
     Next, a groove width L 2  of the inter-pixel light shielding portion  47  necessary for preventing leakage of the incident light into the adjacent pixels and totally reflecting the incident light will be described. 
     It is sufficient if the groove width L 2  of the inter-pixel light shielding portion  47  may be 40 nm or more, assuming that a wavelength (λ) of the incident light is 600 nm, the refractive index (n 2 ) of the semiconductor region  41  is 4.0, the refractive index (n 1 ) of the inter-pixel light shielding portion  47  is 1.5 (corresponding to SiO 2 ), and an incident angle (θ) from the semiconductor region  41  to the inter-pixel light shielding portion  47  is 60°. However, it is desirable that the groove width L 2  of the inter-pixel light shielding portion  47  is 200 nm or more from the viewpoint of a margin satisfying optical characteristics and a process embedding property. 
     A digging amount L 3  of the inter-pixel light shielding portion  47  will be described. 
     The larger the digging amount L 3  of the inter-pixel light shielding portion  47 , the larger the effect of suppressing color mixing. Therefore, the digging amount L 3  can be set to a size equal to the thickness of the semiconductor substrate  12 . That is, the inter-pixel light shielding portion  47  is formed in a state where it penetrates through the semiconductor substrate  12 . In this case, the digging amount L 3  is the same as the thickness of the semiconductor substrate  12 . 
     As illustrated in  FIG.  7   , a case where the inter-pixel light shielding portion  47  has a dug shape without a taper is exemplified, but the inter-pixel light shielding portion  47  may have a tapered shape. 
     The inter-pixel light shielding portion  47  has a tapered shape differing depending on whether or not the inter-pixel light shielding portion  47  is dug from the front surface side of the semiconductor substrate  12  configuring the pixel  2   a,  that is, a side close to the multilayer wiring layer  21 , which is a lower side in  FIG.  7   , or is dug from the back surface side of the semiconductor substrate  12 , that is, an incident surface side, which is an upper side in  FIG.  7   , at the time of manufacturing the inter-pixel light shielding portion  47 . 
     The inter-pixel light shielding portion  47  has a tapered shape in which a side where the digging is started is wide and a side where the digging is ended is narrow. Therefore, in a case where the semiconductor substrate  12  is dug from a front surface side of the pixel  2   a,  the inter-pixel light shielding portion  47  has a tapered shape in which a side of the semiconductor substrate  12  close to the multilayer wiring layer  21  is wide and a side of the semiconductor substrate  12  close to the transparent insulating film  46  is narrow. Furthermore, in a case where the semiconductor substrate  12  is dug from a back surface side of the pixel  2   a,  the inter-pixel light shielding portion  47  has a tapered shape in which a side of the semiconductor substrate  12  close to the transparent insulating film  46  is wide and a side of the semiconductor substrate  12  close to the multilayer wiring layer  21  is narrow. 
     In a case where the inter-pixel light shielding portion  47  has the tapered shape, for example, assuming that the refractive index (n 1 ) of the inter-pixel light shielding portion  47  is 1.5 (corresponding to SiO 2 ) and the refractive index (n 2 ) of the P-type semiconductor region  41  is 4.0, an interface reflectance is very high, and a shape of the inter-pixel light shielding portion  47  can thus be a forward tapered or reverse tapered shape within a range of 0° to 30°. 
     Pixel Structure According to Third Embodiment 
       FIG.  8    is a diagram illustrating a cross-sectional configuration example of a pixel  2   c  according to a third embodiment. 
     In  FIG.  8   , portions corresponding to those of the first embodiment illustrated in  FIG.  2    will be denoted by the same reference numerals, and a description thereof will be appropriately omitted. 
     The third embodiment illustrated in  FIG.  8    is different from the first embodiment described above in that a metal light shielding portion  101  is newly provided with filling a central portion of an inter-pixel light shielding portion  47  having a trench structure arranged between the pixels  2   c  with, for example, a metal material such as tungsten (W) or aluminum (Al). 
     Furthermore, in the third embodiment, a transparent insulating film  46  stacked on a front surface of a pinning layer  45  is formed conformally using, for example, a sputtering method and the like. 
     In a solid-state imaging device  1  according to the third embodiment, color mixing can be further suppressed by further providing the metal light shielding portion  101 . Furthermore, by providing the metal light shielding portion  101 , it becomes possible to reflect incident light in a photoelectric conversion region and condense the incident light by semiconductor regions  41  and  42  in which a photodiode PD is formed, and it is thus possible to improve sensitivity. 
     Pixel Structure According to Fourth Embodiment 
       FIG.  9    is a diagram illustrating a cross-sectional configuration example of a pixel  2   d  according to a fourth embodiment. 
     The pixel  2   d  according to the fourth embodiment has a configuration similar to that of the pixel  2   a  according to the first embodiment except that a material filled in an inter-pixel light shielding portion  47  is a polysilicon (Poly Si) layer  102 . That is, the inter-pixel light shielding portion  47  of the pixel  2   d  includes a pinning layer  45  and the polysilicon layer  102 . 
     Furthermore, as illustrated in the pixel  2   d  illustrated in  FIG.  10   , only the polysilicon layer  102  may be formed in the inter-pixel light shielding portion  47  without forming the pinning layer  45  in the inter-pixel light shielding portion  47 . 
     As described above, the inter-pixel light shielding portion  47  may be formed by filling polycrystalline silicon such as the polysilicon  102  in the inter-pixel light shielding portion  47 . Furthermore, a material having a lower refractive index than that of silicon configuring a semiconductor substrate  12  may be further added as an insulating film in the inter-pixel light shielding portion  47 . 
     Pixel Structure According to Fifth Embodiment 
     Other embodiments of pixel structures will be described with reference to  FIGS.  11  to  19   . In  FIGS.  11  to  19   , a description will be provided using pixel structures illustrated in a simplified manner as compared with the cross-sectional configuration example as illustrated in  FIG.  2   , and the respective corresponding components may be denoted by different reference numbers. 
     Furthermore, in other embodiments of pixel structures described below, a description will be continued by taking a case where a pixel includes a color filter layer  51  as in the pixel  2   a  according to the first embodiment as an example, but the present technology can also be applied to a pixel that does not include the color filter layer  51  as in the pixel  2   b  according to the second embodiment. 
       FIG.  11    is a diagram illustrating a cross-sectional configuration example of a pixel  2   e  according to a fifth embodiment. 
     Although there are portions that overlap the description described above, a configuration of a solid-state imaging device  1  will be described again with reference to  FIG.  11    As illustrated in  FIG.  11   , the solid-state imaging device  1  is configured by stacking an antireflection film  111 , a transparent insulating film  46 , a color filter layer  51 , and an on-chip lens  52  on a semiconductor substrate  12  in which an N-type semiconductor region  42  configuring a photodiode PD is formed for every pixel  2   a.    
     The antireflection film  111  has a stacked structure in which, for example, a fixed charge film and an oxide film are stacked, and for example, an insulating thin film having a high dielectric constant (high-k) by an atomic layer deposition (ALD) method can be used as the antireflection film  111 . Specifically, hafnium oxide (HfO 2 ), aluminum oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), strontium titanium oxide (STO), or the like, can be used. In the example of  FIG.  11   , the antireflection film  111  is configured by stacking a hafnium oxide film  112 , an aluminum oxide film  113 , and a silicon oxide film  114 . 
     Moreover, a light shielding film  49  is formed between the pixels  2   e  so as to be stacked on the antireflection film  111 . A single-layer metal film such as titanium (Ti), titanium nitride (TiN), tungsten (W), aluminum (Al), or tungsten nitride (WN), is used as the light shielding film  49 . Alternatively, a stacked film of these metals (for example, a stacked film of titanium and tungsten, a stacked film of titanium nitride and tungsten, or the like) may be used as the light shielding film  49 . 
     In the solid-state imaging device  1  configured as described above, in the pixel  2   e  according to the fifth embodiment, a flat portion  53  is provided by providing a region of a predetermined width in which a concave portion region  48  is not formed between the pixels  2   e  at a light receiving surface side interface of the semiconductor substrate  12 . As described above, the concave portion region  48  is provided by forming a fine concave structure, and the flat portion  53  is provided by making a flat surface remain without forming the fine concave structure in a region between the pixels  2   e.  As described above, by adopting a pixel structure in which the flat portion  53  is provided, it is possible to suppress generation of diffracted light in a region (pixel separation region) of a predetermined width, which is the vicinity of another adjacent pixel  2   e,  to prevent generation of color mixing. 
     That is, it has been known that in a case where the concave portion region  48  is formed in the semiconductor substrate  12 , diffraction of vertical incident light occurs, and for example, as an interval (pitch) between concave portions increases, a component of diffracted light increases, such that a ratio of light incident on another adjacent pixel  2  increases. 
     On the other hand, in the solid-state imaging device  1 , by providing the flat portion  53  in the region of the predetermined width between the pixels  2   e  in which it is easy for the diffracted light to leak to another adjacent pixel  2   e,  the diffraction of the vertical incident light is not generated in the flat portion  53 , such that it is possible to prevent the generation of the color mixing. 
     In the pixel  2   e  illustrated in  FIG.  11   , a pixel separating portion  54  separating the pixels  2   e  from each other is formed in the semiconductor substrate  12 . The pixel separating portion  54  is formed in a portion corresponding to the inter-pixel light shielding portion  47  in the first to fourth embodiments described above. 
     The pixel separating portion  54  is formed by forming a trench penetrating through the semiconductor substrate  12  between the N-type semiconductor regions  42  configuring the photodiodes PD, forming an aluminum oxide film  113  on an inner surface of the trench, and further embedding an insulator  55  into the trench at the time of forming the silicon oxide film  114 . 
     Note that as in the pixel d (see  FIG.  9    or  FIG.  10   ) according to the fourth embodiment, a configuration in which a portion of the silicon oxide film  114  that is filled in the pixel separating portion  54  includes a polysilicon layer  102  can be applied. 
     By configuring such a pixel separating portion  54 , adjacent pixels  2   e  are electrically completely separated from each other by the insulator  55  embedded in the trench. Therefore, it is possible to prevent charges generated inside the semiconductor substrate  12  from leaking to the adjacent pixel  2   e.    
     Pixel Structure According to Sixth Embodiment 
       FIG.  12    is a diagram illustrating a cross-sectional configuration example of a pixel  2   f  according to a sixth embodiment. 
     In  FIG.  12   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   f  according to the sixth embodiment, a pixel separating portion  54 A completely separating the pixels  2   f  from each other is formed in a semiconductor substrate  12 . 
     The pixel separating portion  54 A is formed by digging a trench penetrating through the semiconductor substrate  12  between N-type semiconductor regions  42  configuring photodiodes PD, forming an aluminum oxide film  113  on an inner surface of the trench, embedding an insulator  55  into the trench at the time of forming a silicon oxide film  114 , and further embedding a light shielding object  56  at the time of forming a light shielding film  49  inside the insulator  55 . The light shielding object  56  includes a metal having a light shielding property so as to be integrated with the light shielding film  49 . 
     By configuring such a pixel separating portion  54 A, adjacent pixels  2   f  are electrically separated from each other by the insulator  55  embedded in the trench, and are optically separated from each other by the light shielding object  56 . Therefore, it is possible to prevent charges generated inside the semiconductor substrate  12  from leaking to the adjacent pixel  2   f,  and it is possible to prevent light from an oblique direction from leaking to the adjacent pixel  2   f.    
     Then, also in the pixel  2   f  according to the sixth embodiment, by adopting a pixel structure in which a flat portion  53  is provided, it is possible to suppress generation of diffracted light in a pixel separation region to prevent generation of color mixing. 
     Pixel Structure According to Seventh Embodiment 
       FIG.  13    is a diagram illustrating a cross-sectional configuration example of a pixel  2   g  according to a seventh embodiment. 
     In  FIG.  13   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   g  according to the seventh embodiment, a pixel separating portion  54 B completely separating the pixels  2   g  from each other is formed in a semiconductor substrate  12 . 
     The pixel separating portion  54 B is formed by digging a trench penetrating through the semiconductor substrate  12  between N-type semiconductor regions  42  configuring photodiodes PD, forming an aluminum oxide film  113  on an inner surface of the trench, embedding an insulator  55  into the trench at the time of forming a silicon oxide film  114 , and further embedding a light shielding object  56  in the trench. 
     The pixel separating portion  54 B of the pixel  2   g  according to the seventh embodiment differs from the pixel  2   f  according to the sixth embodiment in that the light shielding film  49  is not provided in the flat portion  53 . 
     By configuring such a pixel separating portion  54 B, adjacent pixels  2   g  are electrically separated from each other by the insulator  55  embedded in the trench, and are optically separated from each other by the light shielding object  56 . Therefore, it is possible to prevent charges generated inside the semiconductor substrate  12  from leaking to the adjacent pixel  2   g,  and it is possible to prevent light from an oblique direction from leaking to the adjacent pixel  2   g.    
     Then, also in the pixel  2   g  according to the seventh embodiment, by adopting a pixel structure in which the flat portion  53  is provided, it is possible to suppress generation of diffracted light in a pixel separation region to prevent generation of color mixing. 
     Pixel Structure According to Eighth Embodiment 
       FIG.  14    is a diagram illustrating a cross-sectional configuration example of a pixel  2   h  according to an eighth embodiment. 
     In  FIG.  14   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   h  according to the eighth embodiment, a concave portion region  48 A has a shape in which a depth of a concave portion of the concave portion region  48  becomes shallow in the vicinity of the periphery of the pixel  2   h,  and a pixel separating portion  54  is also formed. 
     That is, as illustrated in  FIG.  14   , in the concave portion region  48 A, the concave portion configuring the concave portion region  48 A is formed to have a shallow depth in a peripheral portion of the pixel  2   h,  that is, in a portion which is the vicinity of another adjacent pixel  2   h,  for example, as compared with the concave portion region  48  illustrated in  FIG.  11   . 
     As described above, by forming a concave-convex structure at a shallow depth in the peripheral portion of the pixel  2   h,  it is possible to suppress generation of diffracted light in the peripheral portion of the pixel  2   h.  Also in the pixel  2   h  according to the eighth embodiment, by adopting a pixel structure in which a flat portion  53  is provided, it is possible to suppress generation of diffracted light in a pixel separation region to further prevent generation of color mixing. 
     By forming such a concave portion region  48 A, it is possible to suppress the generation of the diffracted light in the peripheral portion of the pixel  2   h,  and it is possible to electrically separate adjacent pixels  2   h  from each other by the pixel separating portion  54 . Then, also in a sixth variation of a pixel structure, by adopting a pixel structure in which a flat portion  53  is provided, it is possible to suppress generation of diffracted light in a pixel separation region to further prevent generation of color mixing. 
     Pixel Structure According to Ninth Embodiment 
       FIG.  15    is a diagram illustrating a cross-sectional configuration example of a pixel  2   i  according to a ninth embodiment. 
     In  FIG.  15   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   i  according to the ninth embodiment, a concave portion region  48 A has a shape in which a depth of a concave portion configuring the concave portion region  48 A becomes shallow in the vicinity of the periphery of the pixel  2   i,  and a pixel separating portion  54 A is formed. 
     By forming such a concave portion region  48 A, it is possible to suppress generation of diffracted light in a peripheral portion of the pixel  2   i,  and it is possible to electrically and optically separate adjacent pixels  2   i  from each other by the pixel separating portion  54 A. Then, also in the ninth embodiment of the pixel structure, by adopting a pixel structure in which a flat portion  53  is provided, it is possible to suppress generation of diffracted light in a pixel separation region to further prevent generation of color mixing. 
     Pixel Structure According to Tenth Embodiment 
       FIG.  16    is a diagram illustrating a cross-sectional configuration example of a pixel  2   j  according to a tenth embodiment. 
     In  FIG.  16   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   j  according to the tenth embodiment, a concave portion region  48 A has a shape in which a depth of a concave portion configuring the concave portion region  48 A becomes shallow in the vicinity of the periphery of the pixel  2   j,  and a pixel separating portion  54 B is formed. 
     By forming such a concave portion region  48 A, it is possible to suppress generation of diffracted light in a peripheral portion of the pixel  2   j,  and it is possible to electrically and optically separate adjacent pixels  2   j  from each other by the pixel separating portion  54 B. Then, also in the pixel  2   j  according to the tenth embodiment, by adopting a pixel structure in which a flat portion  53  is provided, it is possible to suppress generation of diffracted light in a pixel separation region to further prevent generation of color mixing. 
     Pixel Structure According to Eleventh Embodiment 
       FIG.  17    is a diagram illustrating a cross-sectional configuration example of a pixel  2   k  according to an eleventh embodiment. 
     In  FIG.  17   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   k  according to the eleventh embodiment, a region in which a concave portion region  48 B is formed is narrowed, and a pixel separating portion  54  is formed. 
     That is, as illustrated in  FIG.  17   , in the concave portion region  48 B, a region forming the concave portion region  48 B is reduced in a peripheral portion of the pixel  2   k,  that is, in a portion which is the vicinity of another adjacent pixel  2   k,  for example, as compared with the concave portion region  48  illustrated in  FIG.  11   . Therefore, a flat portion  53 A is formed to be wider than the flat portion  53  of  FIG.  11   . 
     As described above, by providing the flat portion  53 A widely without forming the concave portion region  48 B in the peripheral portion of the pixel  2   k,  it is possible to suppress generation of diffracted light in the peripheral portion of the pixel  2   k.  Therefore, also in the pixel  2   k  according to the eleventh embodiment, it is possible to suppress generation of diffracted light in a pixel separation region to further prevent generation of color mixing. 
     Pixel Structure According to Twelfth Embodiment 
       FIG.  18    is a diagram illustrating a cross-sectional configuration example of a pixel  2   m  according to a twelfth embodiment. 
     In  FIG.  18   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   m  according to the twelfth embodiment, a region in which a concave portion region  48 B is formed is narrowed, and a pixel separating portion  54 A is formed. 
     By forming such a concave portion region  48 B, it is possible to suppress generation of diffracted light in a peripheral portion of the pixel  2   m,  and it is possible to electrically and optically separate adjacent pixels  2   m  from each other by the pixel separating portion  54 A. Then, also in the pixel  2   m  according to the twelfth embodiment, by adopting a pixel structure in which a flat portion  53 A is widely provided, it is possible to suppress generation of diffracted light in a pixel separation region to further prevent generation of color mixing. 
     Pixel Structure According to Thirteenth Embodiment 
       FIG.  19    is a diagram illustrating a cross-sectional configuration example of a pixel  2   n  according to a thirteenth embodiment. 
     In  FIG.  19   , a basic configuration of a solid-state imaging device  1  is common to the configuration illustrated in  FIG.  11   . In the pixel  2   n  according to the thirteenth embodiment, a region in which a concave portion region  48 B is formed is narrowed, and a pixel separating portion  54 B is formed. 
     By forming such a concave portion region  48 B, it is possible to suppress generation of diffracted light in a peripheral portion of the pixel  2   n,  and it is possible to electrically and optically separate adjacent pixels  2   n  from each other by the pixel separating portion  54 B. Then, also in a twenty first variation of a pixel structure, by adopting a pixel structure in which a flat portion  53 A is widely provided, it is possible to suppress generation of diffracted light in a pixel separation region to further prevent generation of color mixing. 
     Application Example To Electronic Apparatus 
     The technology of the present disclosure is not limited to being applied to a solid-state imaging device. That is, the technology of the present disclosure can be applied to all electronic apparatus using a solid-state imaging device in an image capturing unit (photoelectric conversion unit), such as an imaging device such as a digital still camera or a video camera, a portable terminal device having an imaging function, or a copy machine using a solid-state imaging device in an image reading unit. The solid-state imaging device may have a form in which it is formed as a single chip or may have a form of a module in which an imaging unit and a signal processing unit or an optical system are packaged together and which has an imaging function. 
       FIG.  20    is a block diagram illustrating a configuration example of an imaging device as an electronic apparatus according to the present disclosure. 
     The imaging device  200  of  FIG.  20    includes an optical unit  201  including a lens group and the like, a solid-state imaging device (imaging device)  202  in which the configuration of the solid-state imaging device  1  of  FIG.  1    is adopted, and a digital signal processor (DSP) circuit  203  which is a camera signal processing circuit. Furthermore, the imaging device  200  also includes a frame memory  204 , a display unit  205 , a recording unit  206 , an operation unit  207 , and a power supply unit  208 . The DSP circuit  203 , the frame memory  204 , the display unit  205 , the recording unit  206 , the operation unit  207 , and the power supply unit  208  are connected to each other via a bus line  209 . 
     The optical unit  201  takes in incident light (image light) from a subject and forms an image on an imaging surface of the solid-state imaging device  202 . The solid-state imaging device  202  converts an amount of incident light imaged on the imaging surface by the optical unit  201  into an electric signal in pixel units and outputs the electric signal as a pixel signal. As the solid-state imaging device  202 , the solid-state imaging device  1  of  FIG.  1   , that is, the solid-state imaging device having the improved sensitivity while suppressing the deterioration of the color mixing can be used. 
     The display unit  205  includes, for example, a panel-type display device such as a liquid crystal panel or an organic electroluminescence (EL) panel, and displays a moving image or a still image captured by the solid-state imaging device  202 . The recording unit  206  records the moving image or the still image captured by the solid-state imaging device  202  on a recording medium such as a hard disk or a semiconductor memory. 
     The operation unit  207  issues operation commands for various functions of the imaging device  200  under an operation of a user. The power supply unit  208  appropriately supplies various types of power that becomes operation power of the DSP circuit  203 , the frame memory  204 , the display unit  205 , the recording unit  206 , and the operation unit  207  to these supply targets. 
     As described above, by using the solid-state imaging device  1  described above as the solid-state imaging device  202 , it is possible to improve sensitivity while suppressing deterioration of color mixing. Therefore, also in the imaging device  200  such as a video camera, a digital still camera, and a camera module for a mobile apparatus such as a mobile phone, it is possible to improve image quality of a captured image. 
     The embodiments of the present disclosure are not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present disclosure. 
     In the example described above, the solid-state imaging device in which the first conductivity-type is the P-type, the second conductivity-type is the N-type, and electrons are signal charges has been described, but the present disclosure can also be applied to a solid-state imaging device in which holes are signal charges. That is, it is possible to configure each of the semiconductor regions described above by an opposite conductivity-type semiconductor region so that the first conductivity-type is the N-type and the second conductivity-type is the P-type. 
     Furthermore, the technology of the present disclosure is not limited to being applied to a solid-state imaging device that detects a distribution of an incident light amount of visible light to image the distribution of the incident light amount as an image, and can be applied to all solid-state imaging devices (physical quantity distribution detecting devices) such as a solid-state imaging device that images a distribution of an incident amount of infrared rays, X-rays, particles, or the like, as an image, or a fingerprint detection sensor that detects a distribution of another physical quantity such as pressure or capacitance to image the distribution of another physical quantity as an image in a broad sense. 
     Application Example To Endoscopic Surgery System 
     The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system. 
       FIG.  21    is a view illustrating an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied. 
     In  FIG.  21   , an aspect in which an operator (surgeon)  11131  performs surgery on a patient  11132  on a patient bed  11133  using an endoscopic surgery system  11000  is illustrated. As illustrated in  FIG.  21   , the endoscopic surgery system  11000  includes an endoscope  11100 , other surgical tools  11110  such as a pneumoperitoneum tube  11111  or an energy treatment tool  11112 , a support arm device  11120  supporting the endoscope  11100 , and a cart  11200  on which various devices for endoscopic surgery are mounted. 
     The endoscope  11100  includes a lens barrel  11101  whose region of a predetermined length from a tip is inserted into the body cavity of the patient  11132 , and a camera head  11102  connected to a base end of the lens barrel  11101 . The endoscope  11100  configured as a so-called rigid scope having a rigid lens barrel  11101  is illustrated in the illustrated example, but the endoscope  11100  may be configured as a so-called flexible scope having a flexible lens barrel. 
     An opening into which an objective lens is fitted is provided at the tip of the lens barrel  11101 . A light source device  11203  is connected to the endoscope  11100 , such that light generated by the light source device  11203  is guided up to the tip of the lens barrel by a light guide extended inside the lens barrel  11101  and is irradiated toward an observation target in the body cavity of the patient  11132  via the objective lens. Note that the endoscope  11100  may be a forward-viewing endoscope or may be an oblique-viewing endoscope or a side-viewing endoscope. 
     An optical system and an imaging element are provided inside the camera head  11102 , and reflected light (observation light) from the observation target is condensed on the imaging element by the optical system. The observation light is photoelectrically converted by the imaging element, such that an electric signal corresponding to the observation light, that is, an image signal corresponding to an observation image is generated. The image signal is transmitted as RAW data to a camera control unit (CCU)  11201 . 
     The CCU  11201  includes a central processing unit (CPU), a graphics processing unit (GPU), or the like, and comprehensively controls operations of the endoscope  11100  and a display device  11202 . Moreover, the CCU  11201  receives the image signal from the camera head  11102  and performs various image processing for displaying an image based on the image signal, such as development processing (demosaic processing) and the like, on the image signal. 
     The display device  11202  displays the image based on the image signal on which the image processing is performed by the CCU  11201 , under control of the CCU  11201 . 
     The light source device  11203  includes a light source such as, for example, a light emitting diode (LED), and supplies irradiated light to the endoscope  11100  at the time of imaging a surgical site or the like. 
     The input device  11204  is an input interface for the endoscopic surgery system  11000 . A user can input various information or various instructions to the endoscopic surgery system  11000  via the input device  11204 . For example, the user inputs an instruction to change imaging conditions (a type of irradiated light, a magnification, a focal length, and the like) by the endoscope  11100 , and the like. 
     A treatment tool control device  11205  controls the drive of the energy treatment tool  11112  for cautery and incision of tissue, sealing of a blood vessel, or the like. A pneumoperitoneum device  11206  sends a gas into the body cavity via the pneumoperitoneum tube  11111  in order to inflate the body cavity of the patient  11132  for the purpose of securing a visual field by the endoscope  11100  and securing a working space of the operator. A recorder  11207  is a device capable of recording various information regarding the surgery. A printer  11208  is a device capable of printing the various information regarding the surgery in various formats such as a text, an image, or a graph. 
     Note that the light source device  11203  that supplies the irradiated light at the time of imaging the surgical site to the endoscope  11100  can include, for example, a white light source including an LED, a laser light source, or a combination thereof. In a case where the white light source includes a combination of RGB laser light sources, it is possible to control an output intensity and an output timing of each color (each wavelength) with a high accuracy, and it is thus possible to adjust a white balance of a captured image in the light source device  11203 . Furthermore, in this case, by irradiating laser light from each of the RGB laser light sources to the observation target in a time division manner and controlling the drive of the imaging element of the camera head  11102  in synchronization with an irradiation timing of the laser light, it is also possible to capture images corresponding to each of RGB in a time division manner. According to such a method, it is possible to obtain a color image without providing a color filter to the imaging element. 
     Furthermore, the drive of the light source device  11203  may be controlled so as to change an intensity of light output by the light source device  11203  every predetermined time. By controlling the drive of the imaging element of the camera head  11102  in synchronization with a timing of the change in the intensity of the light to acquire images in a time division manner and synthesizing the images with each other, it is possible to generate a high dynamic range image without a so-called black spot and white spot. 
     Furthermore, the light source device  11203  may be configured to be able to supply light of a predetermined wavelength band corresponding to special light observation. In the special light observation, for example, so-called narrow band imaging in which a predetermined tissue such as a blood vessel in a mucous membrane surface layer is imaged with high contrast by irradiating light of a narrow band as compared with irradiated light (that is, white light) at the time of normal observation using wavelength dependency of absorption of light in a body tissue is performed. Alternatively, in the special light observation, fluorescence observation in which an image is obtained by fluorescence generated by irradiating excitation light may be performed. In the fluorescence observation, it can be performed to irradiate excitation light to a body tissue and observe fluorescence from the body tissue (self-fluorescence observation) or locally inject a reagent such as indocyanine green (ICG) or the like to the body tissue and irradiate excitation light corresponding to a fluorescence wavelength of the reagent to the body tissue to obtain a fluorescence image. The light source device  11203  can be configured to be able to supply the light of the narrow band and/or the excitation light corresponding to such special light observation. 
       FIG.  22    is a block diagram illustrating an example of functional configurations of the camera head  11102  and the CCU  11201  illustrated in  FIG.  21   . 
     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 communicably connected to each other by a transmission cable  11400 . 
     The lens unit  11401  is an optical system provided at a connected portion 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 is incident on the lens unit  11401 . The lens unit  11401  is configured by combining a plurality of lenses including a zoom lens and a focus lens with each other. 
     The number of imaging elements configuring the imaging unit  11402  may be one (a so-called single-plate type) or may be plural (a so-called multi-plate type). In a case where the imaging unit  11402  is configured in the multi-plate type, for example, image signals corresponding to each of RGB may be generated by each imaging element, and may be synthesized with each other to obtain a color image. Alternatively, the imaging unit  11402  may include a pair of imaging elements for acquiring respectively image signals for a right eye and a left eye corresponding to a three-dimensional ( 3 D) display. By performing the  3 D display, the operator  11131  can more accurately grasp a depth of a biological tissue in the surgical site. Note that in a case where the imaging unit  11402  is configured in the multi-plate type, a plurality of lens units  11401  may be provided to correspond to the respective imaging elements. 
     Furthermore, the imaging unit  11402  does not need to be necessarily provided in the camera head  11102 . For example, the imaging unit  11402  may be provided immediately after the objective lens, inside the lens barrel  11101 . 
     The drive unit  11403  includes an actuator, and moves the zoom lens and the focus lens of the lens unit  11401  by a predetermined distance along an optical axis under control of the camera head control unit  11405 . Therefore, a magnification and a focus of the captured image by the imaging unit  11402  can be appropriately adjusted. 
     The communication unit  11404  includes a communication device for transmitting and receiving various information to and from 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 . 
     Furthermore, the communication unit  11404  also receives a control signal for controlling the drive of the camera head  11102  from the CCU  11201  and supplies the control signal to the camera head control unit  11405 . The control signal includes, for example, information regarding imaging conditions such as information indicating that a frame rate of the captured image is designated, information indicating that an exposure value at the time of capturing the image is designated, and/or information indicating that a magnification and a focus of the captured image are designated. 
     Note that the imaging conditions such as the frame rate, the exposure value, the magnification, and the focus, described above may be appropriately designated by the user or may be automatically set by the control unit  11413  of the CCU  11201  on the basis of the acquired image signal. In the latter case, a so-called auto exposure (AE) function, an auto focus (AF) function, and an auto white balance (AWB) function are mounted in the endoscope  11100 . 
     The camera head control unit  11405  controls the drive of the camera head  11102  on the basis of the control signal from the CCU  11201  received via the communication unit  11404 . 
     The communication unit  11411  includes a communication device for transmitting and receiving various information to and from the camera head  11102 . The communication unit  11411  receives the image signal transmitted from the camera head  11102  via the transmission cable  11400 . 
     Furthermore, the communication unit  11411  transmits the control signal for controlling the drive of the camera head  11102  to the camera head  11102 . The image signal or the control signal can be transmitted by telecommunication, optical communication or the like. 
     The image processing unit  11412  performs various image processing on the image signal, which is the RAW data transmitted from the camera head  11102 . 
     The control unit  11413  performs various controls related to imaging of the surgical site or the like by the endoscope  11100  and display of the captured image obtained by the imaging of the surgical site or the like. For example, the control unit  11413  generates the control signal for controlling the drive of the camera head  11102 . 
     Furthermore, the control unit  11413  causes the display device  11202  to display the captured image in which the surgical site or the like is imaged, on the basis of the image signal on which the image processing is performed 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 a surgical tool such as forceps, a specific biological site, bleeding, mist at the time of using the energy treatment tool  11112 , and the like, by detecting a shape, a color, or the like of an edge of an object included in the captured image. The control unit  11413  may cause various surgical support information to be superimposed and displayed on an image of the surgical site using a result of the recognition, when the control unit  11413  causes the display device  11202  to display the captured image. The operation support information is superimposed and disposed and is presented to the operator  11131 , such that a burden on the operator  11131  can be reduced or the operator  11131  can certainly perform the surgery. 
     The transmission cable  11400  connecting the camera head  11102  and the CCU  11201  to each other is an electric signal cable corresponding to communication of an electric signal, an optical fiber corresponding to optical communication, or a composite cable of the electric signal cable and the optical fiber. 
     Here, communication has been performed in a wired manner using the transmission cable  11400  in the illustrated example, but communication between the camera head  11102  and the CCU  11201  may be performed in a wireless manner. 
     Application Example to Moving Body 
     The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted in any type of moving body such as a vehicle, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility, an airplane, a drone, a ship, and a robot. 
       FIG.  23    is a block diagram illustrating a schematic configuration example of a vehicle control system which is an example of a moving body control system to which the technology according to the present disclosure can be applied. 
     A vehicle control system  12000  includes a plurality of electronic control units connected to each other via a communication network  12001 . In the example illustrated in  FIG.  23   , the vehicle control system  12000  includes a drive system control unit  12010 , a body system control unit  12020 , an outside-vehicle information detection unit  12030 , an inside-vehicle information detection unit  12040 , and an integrated control unit  12050 . Furthermore, as a functional configuration of the integrated control unit  12050 , a microcomputer  12051 , an audio/image output unit  12052 , and an in-vehicle network interface (I/F)  12053  are illustrated. 
     The drive system control unit  12010  controls operations of devices related to a drive system of the vehicle according to various programs. For example, the drive system control unit  12010  functions as a control device of a driving force generation device for generating a driving force of the vehicle, such as an internal combustion engine, a drive motor, or the like, a driving force transfer mechanism for transferring the driving force to wheels, a steering mechanism for adjusting a steering angle of the vehicle, and a braking device for generating a braking force of the vehicle. 
     The body system control unit  12020  controls operations of various devices mounted on a vehicle body according to various programs. For example, the body system control unit  12020  functions as a control device of a keyless entry system, a smart key system, a power window device, or various lamps such as a headlamp, a back lamp, a brake lamp, a blinker, and a fog lamp. In this case, electric waves or signals of various switches transmitted from a portable device substituting for a key can be input to the body system control unit  12020 . The body system control unit  12020  receives inputs of these electric waves or signals, and controls a door lock device, a power window device, a lamp, and the like of the vehicle. 
     The outside-vehicle information detection unit  12030  detects information regarding the outside of the vehicle in which the vehicle control system  12000  is mounted. For example, an imaging unit  12031  is connected to the outside-vehicle information detection unit  12030 . The outside-vehicle information detection unit  12030  causes the imaging unit  12031  to capture a vehicle external image, and receives the captured image. The outside-vehicle information detection unit  12030  may perform object detection processing or distance detection processing of a person, a vehicle, an obstacle, a sign, characters on a road surface, or the like on the basis of the received image. 
     The imaging unit  12031  is an optical sensor receiving light and outputting an electric signal depending on an amount of received light. The imaging unit  12031  can output the electric signal as an image or can output the electric signal as measured distance information. Furthermore, the light received by the imaging unit  12031  may be visible light or may be non-visible light such as infrared light. 
     The inside-vehicle information detection unit  12040  detects information regarding the inside of the vehicle. For example, a driver state detecting unit  12041  detecting a state of a driver is connected to the inside-vehicle information detection unit  12040 . The driver state detecting unit  12041  includes, for example, a camera imaging the driver, and the inside-vehicle information detection unit  12040  may calculate a fatigue degree or a concentration degree of the driver or may determine whether or not the driver is dozing, on the basis of detected information input from the driver state detecting unit  12041 . 
     The microcomputer  12051  can calculate a control target value of the driving force generation device, the steering mechanism, or the braking device on the basis of the information regarding the inside or the outside of the vehicle acquired by the outside-vehicle information detection unit  12030  or the inside-vehicle information detection unit  12040  and output a control command to the drive system control unit  12010 . For example, the microcomputer  12051  can perform cooperation control for the purpose of realizing a function of an advanced driver assistance system (ADAS) including collision avoidance or shock mitigation of the vehicle, following traveling based on an inter-vehicle distance, vehicle speed maintenance traveling, collision warning of the vehicle, lane departure warning of the vehicle, and the like. 
     Furthermore, the microcomputer  12051  can perform cooperative control for the purpose of automatic driving or the like in which the vehicle autonomously travels without depending on a driver&#39;s operation by controlling the driving force generating device, the steering mechanism, the braking device, or the like, on the basis of the surrounding information of the vehicle acquired by the outside-vehicle information detection unit  12030  or the inside-vehicle information detection unit  12040 . 
     Furthermore, the microcomputer  12051  can output a control command to the body system control unit  12030  on the basis of the information regarding the outside of the vehicle acquired by the outside-vehicle information detection unit  12030 . For example, the microcomputer  12051  can perform cooperative control for the purpose of achieving antiglare such as switching a high beam into a low beam by controlling the headlamp depending on a position of the preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detection unit  12030 . 
     The audio/image output unit  12052  transmits at least one of an audio output signal or an image output signal to an output device capable of visually or auditorily notifying the passenger of the vehicle or the outside of the vehicle of information. In the example of  FIG.  23   , an audio speaker  12061 , a display unit  12062 , and an instrument panel  12063  are exemplified as the output device. The display unit  12062  may include, for example, at least one of an on-board display or a head-up display. 
       FIG.  24    is a view illustrating an example of an installation position of the imaging unit  12031 . 
     In  FIG.  24   , a vehicle  12100  includes imaging units  12101 ,  12102 ,  12103 ,  12104 , and  12105  as the imaging unit  12031 . 
     The imaging units  12101 ,  12102 ,  12103 ,  12104 , and  12105  are provided, for example, at positions such as a front nose, side mirrors, a rear bumper, a back door, and an upper portion of a windshield of a vehicle interior, of the vehicle  12100 . The imaging unit  12101  provided on the front nose and the imaging unit  12105  provided on the upper portion of the windshield of the vehicle interior mainly acquire images of a region in front of the vehicle  12100 . The imaging units  12102  and  12103  provided on the side mirrors mainly acquire images of side regions of the vehicle  12100 . The imaging units  12104  provided on the rear bumper or the back door mainly acquire an image of a region behind the vehicle  12100 . The imaging unit  12105  provided on the upper portion of the windshield in the vehicle interior is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, or the like. 
     Note that  FIG.  24    illustrates an example of imaging ranges of the imaging units  12101  to  12104 . An imaging range  12111  indicates an imaging range of the imaging unit  12101  provided on the front nose, imaging ranges  12112  and  12113  indicate imaging ranges of the imaging units  12102  and  12103  provided on the side mirrors, respectively, and an imaging range  12114  indicates an imaging range of the imaging unit  12104  provided in the rear bumper or the back door. For example, by overlaying image data captured by the imaging units  12101  to  12104  with each other, a bird&#39;s eye view image of the vehicle  12100  viewed from above can be obtained. 
     At least one of the imaging units  12101  to  12104  may have a function of acquiring distance information. For example, at least one of the imaging units  12101  to  12104  may be a stereo camera including a plurality of imaging elements or may be an imaging element having pixels for detecting a phase difference. 
     For example, the microcomputer  12051  can extract, in particular, a three-dimensional object that is the closest three-dimensional object on a traveling road of the vehicle  12100  and travels at a predetermined speed (for example, 0 km/h or more) in a direction that is substantially the same as that of the vehicle  12100  as the preceding vehicle by calculating a distance to each three-dimensional object in the imaging ranges  12111  to  12114  and a temporal change (relative speed to the vehicle  12100 ) in this distance on the basis of the distance information acquired from the imaging units  12101  to  12104 . Moreover, the microcomputer  12051  can set an inter-vehicle distance to be secured in advance in front of the preceding vehicle and perform automatic brake control (including following stop control), automatic acceleration control (including following start control), and the like. As described above, it is possible to perform the cooperative control for the purpose of the automatic driving or the like in which the vehicle autonomously travels without depending on the driver&#39;s operation. 
     For example, the microcomputer  12051  can classify and extract three-dimensional object data regarding the three-dimensional objects into other three-dimensional objects such as a two-wheeled vehicle, an ordinary vehicle, a large vehicle, a pedestrian, and a telephone pole, on the basis of the distance information acquired from the imaging units  12101  to  12104 , and use the three-dimensional object data for automatic avoidance of an obstacle. For example, the microcomputer  12051  identifies obstacles around the vehicle  12100  as obstacles visible to the driver of the vehicle  12100  and obstacles invisible to the driver of the vehicle  12100 . Then, the microcomputer  12051  can perform driving support for collision avoidance by determining a collision risk indicating a risk of collision with each obstacle and outputting a warning to the driver via the audio speaker  12061  or the display unit  12062  or performing forced deceleration or avoidance steering via the drive system control unit  12010  in a situation where the collision risk is a set value or more, such that there is a possibility of collision. 
     At least one of the imaging units  12101  to  12104  may be an infrared camera detecting infrared light. For example, the microcomputer  12051  can recognize a pedestrian by determining whether or not the pedestrian is present in the images captured by the imaging units  12101  to  12104 . Such recognition of the pedestrian is performed by, for example, a procedure for extracting feature points in images captured by the imaging units  12101  to  12104  as the infrared camera and a procedure of performing pattern matching processing on a series of feature points indicating an outline of an object to distinguish whether or not the object is the pedestrian. When the microcomputer  12051  determines that the pedestrian is present in the images captured by the imaging units  12101  to  12104  and recognizes the pedestrian, the audio/image output unit  12052  controls the display unit  12062  to superimpose and display a rectangular outline for emphasizing the recognized pedestrian. Furthermore, the audio/image output unit  12052  may control the display unit  12062  to display an icon or the like indicating the pedestrian on a desired position. 
     In the present specification, a system refers to an entire device including a plurality of devices. 
     Note that effects described in the present specification are merely examples and are not limited, and other effects may be provided. 
     Note that the embodiments of the present technology are not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present technology. 
     Note that the present technology can also have the following configuration. 
     (1)
     A solid-state imaging device including:   a substrate;   a first photoelectric conversion region that is provided in the substrate;   a second photoelectric conversion region that is provided in the substrate;   a trench that is provided between the first photoelectric conversion region and the second photoelectric conversion region and penetrates through the substrate;   a first concave portion region that has a plurality of concave portions provided on a light receiving surface side of the substrate, above the first photoelectric conversion region; and   a second concave portion region that has a plurality of concave portions provided on the light receiving surface side of the substrate, above the second photoelectric conversion region.   

     (2)
     The solid-state imaging device according to the above (1), in which an insulating film is formed in the trench.   

     (3)
     The solid-state imaging device according to the above (1) or (2), in which the trench is filled with a metal material.   

     (4)
     The solid-state imaging device according to the above (2), in which a pinning layer is stacked between the substrate and the insulating film.   

     (5)
     The solid-state imaging device according to the above (2), in which an antireflection film is stacked between the substrate and the insulating film.   

     (6)
     The solid-state imaging device according to any one of the above (1) to (5), in which the concave portion region is formed at a central portion of a pixel, the central portion of the pixel being a region of a predetermined ratio to a pixel region.   

     (7)
     The solid-state imaging device according to any one of the above (1) to (5), in which the concave portion region is formed at a central portion of a pixel, the central portion of the pixel being a region of 80% of a pixel region.   

     (8)
     The solid-state imaging device according to any one of the above (1) to (7), in which a flat portion of a predetermined width in which the concave portion region is not formed is provided between pixels on the light receiving surface side.   

     (9)
     An electronic apparatus including:   a solid-state imaging device including:   a substrate;   a first photoelectric conversion region that is provided in the substrate;   a second photoelectric conversion region that is provided in the substrate;   a trench that is provided between the first photoelectric conversion region and the second photoelectric conversion region and penetrates through the substrate;   a first concave portion region that has a plurality of concave portions provided on a light receiving surface side of the substrate, above the first photoelectric conversion region; and   a second concave portion region that has a plurality of concave portions provided on the light receiving surface side of the substrate, above the second photoelectric conversion region.   

     REFERENCE SIGNS LIST 
     
         
           1  Solid-state imaging device 
           2  Pixel 
           3  Pixel array unit 
           12  Semiconductor substrate 
           41 ,  42  Semiconductor region 
           45  Pinning layer 
           46  Transparent insulating film 
           47  Inter-pixel lighting shielding portion 
           48  Antireflection portion 
           49  Light shielding film 
           50  Flattening film 
           51  Color filter layer 
           52   0 n-chip lens 
           101  Metal light shielding portion 
           200  Imaging device 
           202  Solid-state imaging device