Patent Publication Number: US-2023134765-A1

Title: Electronic device

Description:
TECHNICAL FIELD 
     The present disclosure relates to an electronic device. 
     BACKGROUND ART 
     Electronic devices such as smartphones, mobile phones, or personal computers (PCs) are increasingly mounted with fingerprint sensors. Smartphones and mobile phones are often carried in pockets or bags, so that they need to be thin. In addition, development of a sensor that captures an image of a fingerprint through an optical system is also in progress. On the other hand, if the distance from the finger to be imaged to an imaging unit is decreased, the resolution of the image captured through the optical system may be reduced. 
     CITATION LIST 
     Patent Document 
     
         
         Patent Document 1: WO 2016/114154 
         Patent Document 2: Japanese Patent Application Laid-Open No. 2018-033505 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     One aspect of the present disclosure provides an electronic device capable of suppressing a decrease in resolution even if a distance between an object to be imaged and an imaging unit is further decreased. 
     Solutions to Problems 
     In order to address the above problem, the present disclosure provides an electronic device including a plurality of pixels, 
     in which each of at least two pixels of the plurality of pixels includes: 
     a first lens that collects incident light; 
     a first light shielding film portion having a first hole through which a part of the incident light that has been collected passes; and 
     a photoelectric conversion unit configured to photoelectrically convert the incident light having passed through the first hole, and 
     a shape of the first hole with respect to the first light shielding film portion is different between a first pixel among the at least two pixels and a second pixel different from the first pixel among the at least two pixels. 
     The first pixel may further include a second lens that collects the incident light having been collected by the first lens into the first hole. 
     The first lens may be a reflow lens. 
     A reflow stopper may be provided at a boundary between the two first lenses corresponding to two adjacent pixels. 
     The reflow stopper may include a light shielding material. 
     The electronic device may further include a first optical system that collects incident light on the plurality of pixels, 
     in which the first lens may collect the incident light having been collected through the first optical system, and 
     the first lens may be disposed at a position corresponding to a direction of the incident light incident from a predetermined position through the first optical system. 
     At least one element in a second optical system including the first lens that collects the incident light into the first hole may be a diffraction lens. 
     The shapes of the first holes included in the first pixel and the second pixel may be different corresponding to a shape of a light distribution of a second optical system including the first lens that collects the incident light into the first hole from a predetermined position. 
     The first pixel and the second pixel may be different from each other in a position of the first hole with respect to the first light shielding film portion. 
     The first pixel and the second pixel may be different in an opening area of the first hole. 
     The first hole may include a plasmon filter that has a plurality of holes smaller than the opening. 
     The electronic device may further include a light shielding wall in a plurality of stages arranged between two adjacent pixels among the plurality of pixels. 
     An uppermost portion of the light shielding wall may be provided as the reflow stopper of the reflow lens. 
     In the first pixel and the second pixel, the light shielding wall in a plurality of stages may be arranged at different positions with respect to the photoelectric conversion unit according to a direction of the incident light collected from a predetermined position through a second optical system including the first lens. 
     The first pixel may further include 
     a second light shielding film portion including, on a light entrance side with respect to the first light shielding film portion, a second hole through which a part of the incident light having been collected passes, the second hole being larger than the first hole. The second light shielding portion may be continuously provided with the same material as a metal film of the light shielding wall. 
     The first pixel may further include 
     an antireflection portion having an uneven structure on a surface of the first light shielding film portion on a side of the photoelectric conversion element. 
     The first pixel may further include 
     a photoelectric conversion element separation portion that does not propagate information regarding an intensity of acquired light to the photoelectric conversion unit adjacent to the first pixel. 
     The first pixel may further include 
     a reflection film portion on a bottom part on a side opposite to a light entrance side of the photoelectric conversion element. 
     At least two of the plurality of pixels may be phase detection pixels which are paired. 
     The electronic device may further include an image processing unit that performs processing for restoring resolution of an image by image processing using a point spread function corresponding to the first hole. 
     At least one of the plurality of pixels may be a polarization pixel having a polarizing element, and 
     the electronic device may correct an image signal photoelectrically converted by at least one of the plurality of pixels on the basis of polarization information obtained by polarization by a plurality of the polarizing elements and photoelectric conversion by the photoelectric conversion unit. 
     Each of the plurality of pixels may further include a charge holding unit that is shielded from light, and 
     the electronic device may enable transfer of a charge from the photoelectric conversion element to the charge holding unit, and set exposure timings of the plurality of pixels to be the same. 
     At least two pixels of the plurality of pixels may output image signals on the basis of incident light incident via optical members having wavelengths with different transmission characteristics, and 
     the electronic device may further include an authentication unit determining that an object to be imaged is an artificial object in a case where there is no peak around 760 nanometers on the basis of the image signals output from the at least two pixels. 
     At least two pixels of the plurality of pixels may output image signals on the basis of incident light incident via optical members having wavelengths with different transmission characteristics, and 
     the electronic device may determine that an object to be imaged is an artificial object in a case where there is no rise in a wavelength region from 500 to 600 nanometers on the basis of the image signals output from the at least two pixels. 
     At least two pixels of the plurality of pixels may output image signals on the basis of incident light incident via optical members having wavelengths with different transmission characteristics, and 
     the electronic device may calculate an absorption coefficient spectrum of oxygenated hemoglobin and an absorption coefficient spectrum of reduced hemoglobin on the basis of the image signals output from the at least two pixels, and 
     determine that an object to be imaged is an artificial object in a case where a ratio of a difference value between the absorption coefficient spectrum of the oxygenated hemoglobin and the absorption coefficient spectrum of the reduced hemoglobin at predetermined two wavelengths is outside a predetermined range. 
     The first pixel and the second pixel may be different in a size of the first hole with respect to the first light shielding film portion, and a region of the photoelectric conversion element of the first pixel or the second pixel having the first hole with a larger size may be set to be greater than a region of the photoelectric conversion element of the first pixel or the second pixel having the first hole with a smaller size. 
     Outputs of the plurality of pixels may be addable, and 
     the first hole corresponding to a pixel on a peripheral part of a region where the plurality of pixels is arrayed may be smaller in size than the first hole corresponding to a pixel at a central part of the region. 
     The electronic device may further include a display unit, 
     in which the incident light may be incident on the photoelectric conversion unit via the display unit. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic cross-sectional view of an electronic device according to a first embodiment. 
         FIG.  2 ( a )  is a schematic external view of the electronic device in  FIG.  1   , and  FIG.  2 ( b )  is a cross-sectional view taken along a line A-A in  FIG.  2 ( a ) . 
         FIG.  3 A  is a plan view illustrating an example of an array of a plurality of pixels. 
         FIG.  3 B  is a schematic diagram illustrating an arrangement example of pixels. 
         FIG.  4 A  is a diagram illustrating a cross-sectional structure along the line AA in a case where a multistage lens is used. 
         FIG.  4 B  is a diagram illustrating a specific case excluded from the definition of a pinhole. 
         FIG.  4 C  is a diagram illustrating another example in which an opening area of the pinhole shape is varied for each element. 
         FIG.  5    is a diagram for describing a relationship between an elevation angle and a shift amount. 
         FIG.  6    is a diagram illustrating a distribution of a width W and a height H of the fingerprint. 
         FIG.  7    is a diagram illustrating a correspondence relationship between an elevation angle and a shift amount. 
         FIG.  8 A  is a diagram schematically illustrating a three-dimensional structure of a pixel. 
         FIG.  8 B  illustrates diagrams including left diagrams schematically illustrating the vertical cross section of a pixel  22  and right diagrams which are plan views of a first light shielding film portion. 
         FIG.  9    is a diagram illustrating optical characteristics with respect to the elevation angle. 
         FIG.  10    is a diagram illustrating a structure example in which pupil correction is performed. 
         FIG.  11    is a diagram illustrating optical characteristics with respect to an elevation angle θ at the position of a pinhole  50   a.    
         FIG.  12    is a diagram schematically illustrating a vertical cross section of the pixel illustrated in  FIG.  8   . 
         FIG.  13    is a diagram illustrating a relationship between an elevation angle and a normalized output. 
         FIG.  14 A  is a diagram illustrating integrated sensitivity obtained by integrating normalized outputs. 
         FIG.  14 B  is a diagram illustrating a concept of pupil correction and some derivative examples. 
         FIG.  15    is a diagram schematically illustrating an inner lens and the first light shielding film portion. 
         FIG.  16 A  is a top view of a lens. 
         FIG.  16 B  is a top view of a lens using a reflow lens. 
         FIG.  17 A  shows vertical cross-sectional views of a lens formed by an etching process and a reflow lens. 
         FIG.  17 B  shows vertical cross-sectional views of reflow lenses having bank portions. 
         FIG.  17 C  illustrates vertical cross-sectional views of reflow lenses having bank portions including a transparent material.  FIG.  17 D  illustrates vertical cross-sectional views of reflow lenses having bank portions including a light shielding material. 
         FIG.  18 A  is a diagram illustrating an example of a method for manufacturing a lens by an etch back process. 
         FIG.  18 B  is a diagram illustrating an example of a method for forming a reflow lens. 
         FIG.  18 C  is a diagram illustrating an example of a manufacturing method for forming a reflow lens and a reflow stopper of a bank portion including a metal film. 
         FIG.  18 D  is a diagram illustrating another example of a manufacturing method for forming a reflow lens and a reflow stopper of a bank portion including a metal film. 
         FIG.  18 E  is a diagram illustrating an example of a manufacturing method for forming a reflow lens and a reflow stopper of a bank portion including only a transparent material. 
         FIG.  18 F  is a diagram illustrating an example of a method for forming a reflow lens and a bank portion including a carbon black resist. 
         FIG.  18 G  is a diagram illustrating another example of a method for forming a reflow lens and a bank portion including a carbon black resist. 
         FIG.  19    is a cross-sectional view of a pixel using a reflow lens. 
         FIG.  20    is a cross-sectional view of a pixel using a reflow lens formed as an on-chip lens. 
         FIG.  21    is a cross-sectional view of a pixel using a second light shielding film and a reflow lens. 
         FIG.  22    is a cross-sectional view of a finger surface. 
         FIG.  23    is an image of the vein of the finger captured by an imaging unit. 
         FIG.  24    is a cross-sectional view of a pixel using a diffraction lens. 
         FIG.  25    is a plan view of a diffraction lens at a peripheral part. 
         FIG.  26    is a plan view of a diffraction lens. 
         FIG.  27    is a diagram illustrating an example in which diffraction lenses are arranged in a two-dimensional array. 
         FIG.  28 A  is a diagram illustrating a first light shielding film portion having a circular pinhole. 
         FIG.  28 B  is a diagram illustrating a first light shielding film portion having an octagonal pinhole. 
         FIG.  28 C  is a diagram illustrating a first light shielding film portion having a rectangular pinhole. 
         FIG.  29    is a diagram illustrating an example in which pinhole shapes vary for each pixel. 
         FIG.  30    is a diagram illustrating examples of the shape of pinholes arranged in a two-dimensional array of pixels in the imaging unit. 
         FIG.  31    is a diagram illustrating examples of the shape of pinholes arranged in a one-dimensional row of the two-dimensional array. 
         FIG.  32    is a diagram illustrating an arrangement example of pinhole shapes in a case where outputs of respective pixels are added. 
         FIG.  33 A  is a diagram illustrating a pinhole shape in a central pixel. 
         FIG.  33 B  is a diagram illustrating a pinhole shape in a peripheral pixel. 
         FIG.  34    is a diagram illustrating an example in which a shape inside a pinhole is formed using a plasmon filter. 
         FIG.  35    is a diagram illustrating a configuration example of the plasmon filter in the pinhole. 
         FIG.  36    is a graph illustrating an example of spectral characteristics of the plasmon filter. 
         FIG.  37    is a diagram illustrating spectral characteristics of the plasmon filter in a case where a hole pitch is set to 500 nm. 
         FIG.  38    is a block diagram schematically illustrating a part of an electronic device. 
         FIG.  39    is a diagram illustrating molar extinction coefficients of reduced hemoglobin and oxygenated hemoglobin. 
         FIG.  40    is a diagram illustrating molar extinction coefficients of reduced hemoglobin and oxygenated hemoglobin in a range including a predetermined wavelength. 
         FIG.  41    is a diagram illustrating reflectance of a skin surface. 
         FIG.  42    is a flowchart illustrating a flow of processing performed by the electronic device. 
         FIG.  43 A  is a cross-sectional view of a pixel in a central part of a pixel array. 
         FIG.  43 B  is a diagram illustrating an example in which the pixels are arranged to be shifted toward the center side of the pixel array. 
         FIG.  43 C  is a diagram illustrating an example in which the pixels are arranged to be further shifted from the center side of the pixel array. 
         FIG.  44 A  is a diagram illustrating an example in which a second light shielding film portion is provided below an inner lens. 
         FIG.  44 B  is a diagram illustrating an example in which a third light shielding film portion is provided below a color filter. 
         FIG.  44 C  is a diagram illustrating an example provided with the second light shielding film and the third light shielding film. 
         FIG.  45    is a diagram illustrating an arrangement example of color filters. 
         FIG.  46    is a diagram illustrating wavelength characteristics of the color filters. 
         FIG.  47    is a diagram illustrating an arrangement example of complementary color filters. 
         FIG.  48    is a diagram illustrating wavelength characteristics of the complementary color filters. 
         FIG.  49    is a cross-sectional view of a pixel provided with an antireflection portion and a reflection film. 
         FIG.  50    is a cross-sectional view obtained by cutting out a part of the pixel array. 
         FIG.  51    is a diagram illustrating outputs of pixels having right openings and outputs of pixels having left openings. 
         FIG.  52    is a block diagram schematically illustrating a part of the electronic device  1  according to a ninth embodiment. 
         FIG.  53    is a diagram for describing an example of processing performed by an image processing unit. 
         FIG.  54    is a circuit diagram illustrating a configuration example of a pixel. 
         FIG.  55    is a schematic cross-sectional view of a pixel that can be driven by a global shutter system. 
         FIG.  56    is a diagram illustrating a polarization pixel, a light-shielding pixel, and a phase pixels provided in the pixel array. 
         FIG.  57    is a cross-sectional view of the polarization pixel. 
         FIG.  58    is a diagram illustrating a configuration example of a polarizing unit. 
         FIG.  59    is a block diagram schematically illustrating a part of an electronic device according to a twelfth embodiment. 
         FIG.  60    is a diagram for describing an example of processing performed by an analysis unit. 
         FIG.  61    is a diagram illustrating an arrangement example of a light source. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Embodiments of the electronic device will be described below with reference to the drawings. Although main components of the electronic device will be mainly described below, the electronic device may have components and functions that are not illustrated or described. The following description does not exclude components and functions that are not illustrated or described. 
     First Embodiment 
       FIG.  1    is a schematic cross-sectional view of an electronic device  1  according to a first embodiment. An electronic device  1  in  FIG.  1    is any electronic device having both a display function and an imaging function, such as a smartphone, a mobile phone, a tablet, or a PC.  FIG.  1 ( a )  is an example of the electronic device  1  having an optical system, and  FIG.  1 ( b )  is an example of the electronic device  1  having no optical system. The electronic device  1  in  FIG.  1    includes a camera module (imaging unit) disposed on a side opposite to a display surface of a display unit  2 . As described above, in the electronic device  1  in  FIG.  1   , the camera module  3  is provided on the back side of the display surface of the display unit  2 . Therefore, the camera module  3  performs image capture through the display unit  2 . 
       FIG.  2 ( a )  is a schematic external view of the electronic device  1  in  FIG.  1   , and  FIG.  2 ( b )  is a cross-sectional view taken along a line A-A in  FIG.  2 ( a ) . In the example of  FIG.  2 ( a ) , a display screen  1   a  extends to an area close to the outer size of the electronic device  1 , and the width of a bezel  1   b  around the display screen  1   a  is set to several mm or less. Normally, a front camera is often mounted on the bezel  1   b , but in  FIG.  2 ( a ) , the camera module  3  functioning as a front camera is disposed on the back side of the substantially central portion of the display screen  1   a  as indicated by a broken line. Providing the front camera on the back side of the display screen  1   a  in this manner eliminates the need to dispose the front camera in the bezel  1   b , thereby being capable of reducing the width of the bezel  1   b.    
     Note that, although the camera module  3  is disposed on the back side of the substantially central portion of the display screen  1   a  in  FIG.  2 ( a ) , it is sufficient in the present embodiment that the camera module  3  is disposed on the back side of the display screen  1   a . For example, the camera module  3  may be disposed on the back side of the display screen  1   a  near the peripheral edge. In this manner, the camera module  3  in the present embodiment is disposed at any position on the back side overlapping the display screen  1   a.    
     As illustrated in  FIG.  1   , the display unit  2  is a structure in which a display panel  4 , a touch panel  5 , a circularly polarizing plate  6 , and a cover glass  7  are layered in this order. The display panel  4  may be, for example, an organic light emitting device (OLED) unit, a liquid crystal display unit, a microLED, or the display unit  2  based on other display principles. The display panel  4  such as the OLED unit includes a plurality of layers. The display panel  4  is often provided with a member having low transmittance such as a color filter layer. The member having low transmittance in the display panel  4  may be formed with a through hole according to an installation place of the camera module  3 . If it is designed in such a manner that subject light passing through the through hole is incident on the camera module  3 , the image quality of an image captured by the camera module  3  can be improved. 
     The circularly polarizing plate  6  is provided to reduce glare and enhance visibility of the display screen  1   a  even in a bright environment. The touch panel  5  has incorporated therein a touch sensor. There are various types of touch sensors such as a capacitive type and a resistive type, and any type may be used for the touch sensor. In addition, the touch panel  5  and the display panel  4  may be integrated. The cover glass  7  is provided to protect the display panel  4  and the like. 
     The camera module  3  illustrated in  FIG.  1 ( a )  includes an imaging unit  8  and an optical system  9 . The optical system  9  is disposed on the light entrance surface side of the imaging unit  8 , that is, on the side close to the display unit  2 , and collects light passing through the display unit  2  on the imaging unit  8 . The optical system  9  may be constituted by a plurality of lenses, and this may prevent the reduction in thickness of a housing. As a solution, using a Fresnel lens is conceivable, but there is a processing limit. The present invention provides a solid-state imaging element capable of imaging a fingerprint without impairing resolution even without an optical lens. However, the combination with the optical lens is not excluded. 
     First, a case where a pixel  22  of the imaging unit  8  includes a multistage lens will be described.  FIG.  3 A  is a plan view of an array structure in which a plurality of pixels  22  of the imaging unit  8  is viewed from the light entrance side. As illustrated in  FIG.  3 A , the imaging unit  8  includes a plurality of pixels  22 . The plurality of pixels  22  is provided in an array along a first direction and a second direction intersecting the first direction. Note that the arrangement of the pixels is illustrated as an example, and the pixels are not necessarily provided in a rectangular shape or along the first direction and the second direction. 
       FIG.  3 B  is a schematic diagram illustrating an arrangement example of the pixels  22 . (a) illustrates an example in which the plurality of pixels  22  is provided in an array along the first direction and the second direction intersecting the first direction as in  FIG.  3 A . 
     (b) is a diagram illustrating an array in which the pixels  22  are rotated by 45 degrees with respect to the array in (a). Since the pitch of the pixels can be reduced to 1/√2, it is possible to achieve high resolution while maintaining imaging characteristics. 
     (c) is a diagram illustrating an example in which the pixels  22  are arrayed into a regular hexagon. The regular hexagon has the shortest circumference among figures that can be filled in a plane, and the resolution can be efficiently increased. Then, the risk of initial failure can be reduced by providing the hexagonal pixel having a high stress dispersion effect against each of stress concentration that occurs when trench element isolation for suppressing crosstalk is formed on a substrate, stress concentration that occurs during trench processing of a light shielding wall  61  and the like to be described later, and stress concentration that occurs due to embedding of metal or an insulating film in a trench. 
     Furthermore, in a case where the substrate is provided with trench element isolation for suppressing crosstalk or the light shielding wall  61  includes a cross portion, processing variation occurs in the depth direction due to a micro loading effect at the time of etching. In this case, four lines are needed to be aligned in the rectangular shape, whereas three lines are needed to be aligned in the hexagonal shape, whereby a processing variation of micro loading can be suppressed. 
     (d) illustrates an example in which the pixels  22  are arrayed into a parallel octagonal shape. Note that the pixels  22  in the parallel octagonal shape may be formed into a honeycomb structure. 
     Pixels  22   x  and  22   p  indicate examples of pixels arranged side by side. 
       FIG.  4 A  is a diagram illustrating a cross-sectional structure of the pixels  22   x  and  22   p  along a line AA in the present embodiment in  FIG.  3    in a case where the pixels  22   x  and  22   p  have multistage lenses. As illustrated in  FIG.  4 A , in the imaging unit  8 , an n-type semiconductor region is formed in, for example, a p-type semiconductor region of a semiconductor substrate  12  for each of the pixels  22   x  and  22   p , whereby a photoelectric conversion element PD is formed for each pixel. On the front surface side (lower side in the drawing) of the semiconductor substrate  12 , a multilayer wiring layer including a transistor for performing reading of charges accumulated in the photoelectric conversion element PD, and the like and an interlayer insulating film are formed. 
     An insulating layer  46  having a negative fixed charge is formed at an interface on the back surface side (upper side in the drawing) of the semiconductor substrate  12 . The insulating layer  46  includes a plurality of layers having different refractive indexes, for example, two layers of a hafnium oxide (HfO2) film  48  and a tantalum oxide (Ta2O5) film  47 , and the insulating layer  46  electrically suppresses dark current by pinning enhancement and optically functions as an antireflection film. 
     A silicon oxide film  49  is formed on the upper surface of the insulating layer  46 , and a first light shielding film portion  50  formed with a pinhole  50   a  is formed on the silicon oxide film  49 . The first light shielding film portion  50  only needs to include a material that shields light, and preferably includes a film of metal, for example, aluminum (Al), tungsten (W), or copper (Cu) as a material having a high light shielding property and capable of being accurately processed by microfabrication, for example, etching. The first light shielding film portion  50  is formed with the pinhole  50   a  and suppresses color mixture between pixels and light of a flare component incident at an unexpected angle. 
     Note that the pinhole in the present embodiment will be described.  FIG.  4 B  is a diagram illustrating a specific case excluded from the definition of the pinhole. For example, (a) is a diagram illustrating an example of an opening shape often seen in a light-shielding metal of an image plane phase detection pixel. Such a shape is not a pinhole but is referred to as a slit shape in the present embodiment. On the other hand, (b) is a diagram illustrating an opening shape that is often seen when a stray light suppressing effect is intended. Such an opening having a large area ratio is referred to as inter-pixel light shielding for suppressing crosstalk to an adjacent pixel or an aperture diaphragm in the present embodiment. 
     On the other hand, a mode in which the shape of the opening with respect to the light shielding film satisfies the following conditions (1) to (3) is defined as a pinhole according to the present embodiment. 
     (1) The long side of the opening is ⅓ or less of the pixel size 
     (2) Opening area/pixel area≤10% 
     (3) The opening is provided in the vicinity of an image forming surface of the lens 
     Regarding the vicinity of the image forming surface in (3), a region at least within ±2 μm, preferably within ±1 μm from the image forming surface is defined as the vicinity of the image forming surface in the present embodiment, considering that the depth of focus of the field changes depending on the optical path design. 
     Returning to  FIG.  4 A  again, the light shielding wall  61  and a flattened film  62  having high light transmittance are formed in a plurality of stages on the first light shielding film portion  50  and the insulating layer  46 . More specifically, a first light shielding wall  61 A is formed in a part of a region on the first light shielding film portion  50  between pixels, and a first flattened film  62 A is formed between the first light shielding walls  61 A. Furthermore, a second light shielding wall  61 B and a second flattened film  62 B are formed on the first light shielding wall  61 A and the first flattened film  62 A. Note that the light shielding wall herein may include metal, for example, a material such as tungsten (W), titanium (Ti), aluminum (Al), or copper (Cu), an alloy thereof, or a multilayer film of these metals. Alternatively, the light shielding wall may include an organic light shielding material such as carbon black. Alternatively, the light shielding wall may include a transparent inorganic film as long as it has a structure for suppressing crosstalk by a total reflection phenomenon due to a difference in refractive index. For example, a shape in which the uppermost portion is closed may be applied as an air gap structure. 
     For example, a color filter  71  is formed for each pixel on the upper surfaces of the second light shielding wall  61 B and the second flattened film  62 B. The color filters  71  are provided in such a manner that R (red), G (green), and B (blue) are arranged in, for example, the Bayer arrangement, but another arrangement method may be used. Alternatively, the imaging unit  8  may not include the color filter  71 . 
     An on-chip lens  72  is formed on the color filter  71  for each pixel. The on-chip lens  72  may include, for example, an organic material such as a styrene resin, an acrylic resin, a styrene-acrylic copolymer resin, or a siloxane resin. The styrene resin has a refractive index of about 1.6, and the acrylic resin has a refractive index of about 1.5. The styrene-acrylic copolymer resin has a refractive index of about 1.5 to 1.6, and the siloxane resin has a refractive index of about 1.45. 
     An inner lens  121  includes an inorganic material such as SiN or SiON. The inner lens  121  is formed on the formed first light shielding wall layer (the first light shielding wall  61 A and the first flattened film  62 A). 
       FIG.  4 C  is a diagram illustrating another example in which the opening area of the pinhole is varied for each pixel. The upper diagram on the left side illustrates a vertical cross section of the pixel  22 , the lower diagram on the left side illustrates a plan view of the first light shielding film portion  50 , and the right diagram illustrates a plan view of the semiconductor substrate  12 . As the size of the pinhole  50   a  increases, the region of the photoelectric conversion element increases. That is, the size of the pinhole  50   a  corresponding to a photoelectric conversion element PD 2  is larger than the size of the pinhole  50   a  corresponding to a photoelectric conversion element PD 1 . In a case where the pinholes  50   a  have different sizes, electrons previously accumulated in the photoelectric conversion element corresponding to the pinhole  50   a  having a large opening size are likely to reach a saturation state, and a risk of the electrons leaking to the adjacent pixel due to blooming increases. In the pixels  22  according to the present embodiment, the areas of the photoelectric conversion elements PD 1  and PD 2  vary so as to correspond to the areas of the pinholes  50   a . As a result, the possibility of occurrence of blooming can be leveled between large openings and small openings. In addition, due to the configuration in which the photoelectric conversion elements PD 1  and PD 2  having regions with different sizes are provided, it is possible to simultaneously acquire a high-sensitivity image and a high-resolution image. Furthermore, it is also possible to obtain a wide dynamic range by synthesizing a high-sensitivity image and a high-resolution image. 
     First, an elevation angle θ in a case where a fingerprint is imaged by the imaging unit  8  will be described with reference to  FIG.  5   . In the case of capturing an image of a fingerprint, light scattered in a finger resulting from imaging light incident on the finger is captured by the imaging unit  8 , for example. 
       FIG.  5    is a diagram for describing the relationship between the elevation angle θ and a shift amount d in a case where the fingerprint of the finger is imaged by the imaging unit  8 . As illustrated in  FIG.  5   , the fingerprint is an impression formed by friction ridges that are formed by pores of the sweat gland on the skin of the fingertip raising along an arc. A point at which light having an elevation angle θ from a first point of the imaging surface of the imaging device  8  is incident from the lower surface of the display unit (display unit)  2  and emitted from the upper surface of the display unit  2  is defined as a second point. In this case, the shift amount d [μm] is a distance between the second point and an intersection between a vertical upward line extending perpendicularly from the first point and the upper surface of the display unit (display unit)  2 . In addition, the width of the friction ridge is indicated by W, and the height thereof is indicated by H. Note that, in the present embodiment, the width W of the friction ridge is referred to as a fingerprint pitch. 
     The thickness of the common display unit  2  is, for example, about 800 μm. In addition, the display unit  2  includes the display panel  4 , the touch panel  5 , the circularly polarizing plate  6 , and the cover glass  7  ( FIG.  1   ) as described above. These components are constituted by various members such as glass, polyimide resin, polarizing plate, and wave plate. When calculation is performed by mean field approximation in consideration of the thicknesses and refractive indexes of these components, the average refractive index of the display unit  2  that can be obtained as a representative value is, for example, 1.5. On the other hand, the distance between the lower surface of the display unit  2  and the surface of the on-chip lens of the imaging device  8  is designed to be, for example, 200 μm. 
     Next, the distribution of the width W and the height H of the friction ridges will be described with reference to  FIG.  6   .  FIG.  6    is a diagram illustrating the distribution of the width W and the height H of the fingerprint. The horizontal axis represents the width W of the friction ridges, and the vertical axis represents the height H of the friction ridges. As illustrated in  FIG.  6   , the average friction ridge of the fingerprint has a width W of approximately 400 micrometers and a height H of approximately 100 micrometers. 
     Next, a correspondence relationship between the elevation angle θ and the shift amount d will be described with reference to  FIG.  7   .  FIG.  7    is a diagram illustrating a correspondence relationship between the elevation angle θ and the shift amount d. 
     A line L 70  indicates a correlation derived by the Snell&#39;s law in the case of the arrangement example of  FIG.  5   . For example, a half pitch of the fingerprint pitch of 400 μm corresponds to the elevation angle of 15 degrees from the correlation indicated by the line L 70 . 
     Here, optical characteristics of the pinhole  50   a  ( FIG.  4   ) provided in the first light shielding film portion  50  ( FIG.  4   ) that suppresses a decrease in imaging resolution will be described with reference to  FIGS.  8 A to  11   , while referring to  FIG.  7   . 
       FIG.  8 A  is a diagram schematically illustrating a three-dimensional structure of the pixel  22  constituting the imaging unit  8 . As illustrated in  FIG.  8 A , the pixel having a multistage lens in the present embodiment has, for example, a rectangular shape with a base of 6×6 μm, and is designed to have a focus on the first light shielding film portion  50 . In this case, the distance from the first light shielding film portion  50  to the vertex of the on-chip lens is, for example, 8 μm. 
     In  FIG.  8 B , left diagrams schematically illustrate the vertical cross section of the pixel  22  illustrated in  FIG.  8 A , and right diagrams illustrate plan views of the first light shielding film portion  50 . Here, (a) shows a reference structure without a pinhole. (b) to (d) illustrate examples in which the diameter of the circular pinhole  50   a  of the first light shielding film portion  50  is 0.7, 1.0, and 1.3 μm, respectively. The opening area ratios of the first light shielding film portions  50  illustrated in (a) to (d) are 64%, 1%, 2%, and 4%, respectively. As described above, the shape of the first light shielding film portion  50  can be changed according to the purpose of image capture of the pixel  22 . 
     Oblique incidence characteristics with respect to the four modes illustrated in (a) to (d) of  FIG.  8 B  will be described with reference to  FIG.  9   . 
       FIG.  9    is a diagram illustrating optical characteristics with respect to the elevation angle θ of the pixel  22  illustrated in  FIG.  7   . The horizontal axis represents the elevation angle θ, and the vertical axis represents the normalized output when the output of a large opening pixel without a pinhole is 1. In the case of the circular pinhole  50   a  having a diameter of 1.3 μm, light having substantially the same intensity enters the photoelectric conversion element PD when the elevation angle θ is from 0 degrees to 4 degrees, as illustrated in  FIG.  9   . On the other hand, when the elevation angle θ exceeds 4 degrees, an amount of incident light starts to decrease, and becomes about 20% of the normalized output at 10 degrees. As described above, in the case of the circular pinhole  50   a  having a diameter of 1.3 μm in the arrangement example of the optical system illustrated in  FIG.  8 B , the amount of incident light starts to decrease when the elevation angle θ exceeds 4 degrees. In other words, the amount of incident light at the elevation angle θ of 4 degrees or more is suppressed. 
     Next, in the case of the circular pinhole  50   a  having a diameter of 1.0 μm, light having substantially the same intensity enters the photoelectric conversion element PD when the elevation angle θ is from 0 degrees to 2 degrees. On the other hand, when the elevation angle θ exceeds 2 degrees, an amount of incident light starts to decrease, and becomes about 5% of the normalized output at 10 degrees. As described above, in the case of the circular pinhole  50   a  having a diameter of 1.0 μm in the arrangement example of the optical system illustrated in  FIG.  8 B , the amount of incident light starts to decrease when the elevation angle θ exceeds 2 degrees. In other words, the amount of incident light at the elevation angle θ of 2 degrees or more is suppressed. 
     Next, in the case of the circular pinhole  50   a  having a diameter of 0.7 μm, the amount of incident light starts to decrease from the point at which the elevation angle θ is 0 degrees, and becomes about 2% of the normalized output at 10 degrees. As described above, in the case of the circular pinhole  50   a  having a diameter of 0.7 μm, vignetting is already produced in normally incident light. The vignetting according to the present embodiment refers to a state in which only a part of the light distribution passes through the pinhole  50   a . As described above, although the sensitivity decreases due to the reduction in size of the pinhole, the resolution is further increased. 
     As illustrated in  FIG.  9   , the amount of light incident on the photoelectric conversion element PD with respect to the elevation angle θ can be adjusted by the size of the pinhole  50   a  provided in the first light shielding film portion  50 . As a result, by adjusting the size of the pinhole  50   a  provided in the first light shielding film portion  50 , the pixel  22  can be configured to have a resolution corresponding to the imaging purpose. As described above, the resolution and the normalized output of the pixel  22  can be adjusted by the size of the pinhole  50   a.    
       FIG.  10    is a diagram illustrating an example of a structure in which pupil correction is performed to efficiently receive obliquely incident light with respect to the structure of  FIG.  8 B .  FIG.  10    schematically illustrates only the drawing corresponding to the example in which the diameter of the pinhole  50   a  is 1.0 μm in  FIG.  8 B . 
       FIG.  11    is a diagram illustrating optical characteristics with respect to the elevation angle θ at the position of the pinhole  50   a  illustrated in  FIG.  10   . The horizontal axis represents the elevation angle θ, and the vertical axis represents the normalized output when the output of a large opening pixel without a pinhole at 0 degrees is 1. In the following, the above definition of the “normalized output” is used unless otherwise specified. Four modes in total are illustrated which are the reference structure having no pinhole in the first light shielding film portion  50  and the structures having circular pinholes  50   a  in the first light shielding film portions  50  with diameters of 0.7, 1.0, and 1.3 μm. These structures are configuration examples corresponding to an oblique incidence angle of 27 degrees. As can be seen from these structures, the peak of a light receiving angle is shifted from 0 degrees. In addition, the sensitivity decreases as compared with  FIG.  10    illustrating the structures without pupil correction. This is because the light intensity distribution is widened by oblique incidence. 
     More specifically, in the case of the circular pinhole  50   a  having a diameter of 1.3 μm, an amount of incident light reaches a peak at the elevation angle θ of 27 degrees, and decreases as the elevation angle θ is shifted from 27 degrees, as illustrated in  FIG.  11   . Vignetting is produced in obliquely incident light. When the elevation angle θ is 37 degrees, the amount of incident light is about 20% of the normalized output. As described above, in the case of the circular pinhole  50   a  having a diameter of 1.3 μm in the arrangement example of the optical system illustrated in  FIG.  10   , the amount of incident light starts to decrease when the elevation angle θ exceeds 27 degrees. 
     Next, in the case of the circular pinhole  50   a  having a diameter of 1.0 μm, an amount of incident light reaches a peak at the elevation angle θ of 27 degrees, and decreases as the elevation angle θ is shifted from 27 degrees. When the elevation angle θ is 35 degrees, the amount of incident light is about 20% of the normalized output. 
     Next, in the case of the circular pinhole  50   a  having a diameter of 0.7 μm, an amount of incident light reaches a peak at the elevation angle θ of 27 degrees, and decreases as the elevation angle θ is shifted from 27 degrees. When the elevation angle θ is 32 degrees, the amount of incident light is about 20% of the normalized output. As described above, as the diameter of the pinhole  50   a  decreases, the difference between the elevation angle at which the amount of incident light is about 20% of the normalized output and the elevation angle at which the amount of incident light has a peak value further decreases. That is, even in oblique incidence, the resolution increases as the diameter of the pinhole  50   a  decreases. 
     Further, the sensitivity decreases due to the reduction in size of the pinhole  50   a . As described above, the reduction in size of the pinhole  50   a  further accelerates an increase in resolution, although causing a decrease in sensitivity. The commercial value can be increased by applying such pupil correction. For example, in the lensless electronic device  1  in  FIG.  5   , an angle of view is increased by approximately 0.8 mm by linearly applying pupil correction for obtaining the optical characteristics illustrated in  FIG.  11    at the angle of view end such that the lens shifts outward from the chip center toward the angle of view end. 
     Here, the optical characteristics of the pixel  22  according to the layer thickness between the bottom part of the inner lens  121  ( FIG.  4   ) and the first light shielding film portion  50  ( FIG.  4   ) provided with the pinhole  50   a  will be described with reference to  FIGS.  12  to  15   . 
       FIG.  12    is a diagram schematically illustrating a vertical cross section of the pixel  22  illustrated in  FIG.  8   . In the following, optical characteristics according to the layer thickness distribution between the bottom part of the inner lens  121  ( FIG.  4   ) and the first light shielding film portion  50  ( FIG.  4   ) will be described. 
       FIG.  13    is a diagram illustrating a relationship between the elevation angle θ according to the layer thickness between the bottom part of the inner lens  121  and the first light shielding film portion  50  and the normalized output. A graph indicating the case where the layer thickness between the inner lens  121  and the first light shielding film portion  50  is a layer thickness in an in-focus state (just focus) is illustrated in the center, and graphs indicating the cases where the layer thickness is −0.3 micrometers and −0.6 micrometers from the thickness in the in-focus state are sequentially illustrated on the left side. Similarly, graphs indicating the cases where the layer thickness is +0.3 micrometers and +0.6 micrometers from the thickness in the in-focus state are sequentially illustrated on the right side. The horizontal axis of the angular graph represents the elevation angle θ, and the vertical axis represents the normalized output of the pixel  22 . The horizontal axis of the angular graph ranges from −10 degrees to 10 degrees, and the midpoint is 0 degrees. 
       FIG.  14 A  is a diagram illustrating integrated sensitivity obtained by integrating normalized outputs in the graphs illustrated in  FIG.  13    at the elevation angle of −4 degrees to 4 degrees. The horizontal axis represents a defocus amount with respect to the layer thickness in an in-focus state (just focus). The vertical axis represents a relative value of the integrated sensitivity of each graph ( FIG.  13   ) in a case where the integrated sensitivity in the in-focus state (just focus) is 1. As illustrated in  FIG.  14   , the integrated sensitivity is maintained at 0.95 or more within a range where the absolute value of the defocus amount is up to 0.3 micrometers. 
       FIG.  14 B  is a diagram illustrating a concept of pupil correction and some derivative examples according to the present embodiment. In a case where pupil correction is not performed, each pixel captures only light perpendicularly incident from a subject facing the pixel, and the chip size and the subject size become equal. However, it is desirable that the chip size can be made as small as possible in view of suppression of the manufacturing cost by increasing the number of chips that can be obtained in a wafer and a potential demand for reducing the occupied area in a housing on the set side. Pupil correction is considered as a means for achieving the above demands. The above demands can be achieved by angle control at the position of the pinhole as in (a), angle control by shifting the lens system with respect to the light shielding wall as in (b), or a combination thereof as in (c). 
       FIG.  15    is a diagram schematically illustrating the on-chip lens  72  and the first light shielding film portion  50 . Lines L 2  to L 6  indicate ranges of light fluxes collected through the on-chip lens  72 . (a) illustrates an example in which the pinhole of the first light shielding film portion  50  is provided in the central portion, and (b) illustrates an example in which the pinhole is shifted to the left side. The pixel  22  indicated in (a) is disposed, for example, at the center of the imaging unit  8 , and the pixel  22  indicated in (b) is disposed, for example, at the right end of the imaging unit  8 . 
     (a) which is on the left side illustrates a case where the layer thickness between the on-chip lens  72  and the first light shielding film portion  50  is in an in-focus state (just focus) at the chip center. In this case, at the angle of view end indicated in (b), the optical path length becomes longer than the optical path length of the pixel indicated in (a), so that shift to a front focus state may occur. Therefore, it is desirable to optimize the light collection point in consideration of the pixel  22  at the angle of view end illustrated in (b), as in the example on the right side. In this case, a back focus state is generated for the pixel  22  illustrated in (a). However, generating the back focus state enables reduction in thickness of the on-chip lens  72  and the reduction in layer thickness between the bottom part of the on-chip lens  72  and the first light shielding film portion  50 . Furthermore, overall optimization may be performed on each of the pixels  22  illustrated in (a) and (b) by performing intermediate focusing. In this case, a back focus state is also generated for the pixel  22  illustrated in (a), and thus, it is possible to reduce the thickness of the on-chip lens  72  and to reduce the layer thickness between the bottom part of the on-chip lens  72  and the first light shielding film portion  50 . Note that, even when the back focus state is generated, the decrease in the integrated sensitivity is gentle as illustrated in  FIG.  14 A , so that the integrated sensitivity can be maintained. 
     As described above, the present embodiment indicates that the pixel  22  of the imaging unit  8  includes the on-chip lens  72  and the first light shielding film portion  50 . However, the present embodiment can be applied to a configuration illustrated in  FIG.  8    having a multistage lens obtained by adding the inner lens  121 . Since the pinhole  50   a  is provided in the first light shielding film portion  50  of the pixel  22 , the optical characteristics including the high resolution and the normalized output of the pixel  22  can be adjusted by adjusting the size of the pinhole  50   a . Furthermore, due to the configuration in which the pixel  22  has a multistage lens including the on-chip lens  72  and the inner lens  121 , the light-collecting power of the optical system of the pixel  22  can be increased. Furthermore, by adjusting the layer thickness between the inner lens  121  and the first light shielding film portion  50 , the focusing state such as the back focus state can be adjusted with respect to the pinhole  50   a . When the layer thickness decreases due to the generation of the back focus state, a PAD opening process is facilitated, and the thickness of the imaging unit can be reduced. 
     Next, a case where a reflow lens is used for the on-chip lens  72  will be described. For example, a material obtained by dissolving an acrylic resin in a PGMEA solvent and adding a photosensitizer thereto is used for the reflow lens. The material is applied to a substrate by spin coating, and exposed and developed. Thereafter, a lens shape is formed by reflow by heat treatment, and bleaching treatment is performed with ultraviolet rays. Unlike an etch back process, the reflow lens has a problem that a gapless structure is difficult, but the number of steps is small, and a PAD region can be removed by exposure. Therefore, it is advantageous for forming a thick lens of a large pixel. 
       FIG.  16 A  is a top view of an example of the lens  72 . As illustrated in  FIG.  16 A , the method for transfer to the lens material by the etch back process makes it possible to narrow the gap between the lenses by deposited materials during etching. That is, the sensitivity can be enhanced by narrowing an ineffective region of the lens. On the other hand, according to the Fraunhofer diffraction theory, when the refractive index of a medium is n, the focal length is f, and the lens size is D, the spot radius coo when the light having a wavelength A is collected can be approximately expressed by Expression (1). 
     
       
         
           
             [ 
             
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                     ω 
                     0 
                   
                   = 
                   
                     
                       1.22 
                           
                       f 
                       ⁢ 
                       λ 
                     
                     nD 
                   
                 
               
               
                 
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     That is, the spot radius coo can be decreased as the thickness of the lens is increased and the focal length f is shortened, or as the lens size D is increased. 
     However, when it is intended to increase the thickness of the lens while increasing the size of the lens, there arises a problem that an amount of deposited materials in a chamber increases due to an increase in a processing amount of etching for the lens material, which leads to an increase in maintenance frequency. It is considered that the limit of the lens thickness is about 3 to 4 μm from the viewpoint of operating the device. On the other hand, it is conceivable to increase the size of the pixel with a thin lens, but in this case, the horizontal and diagonal curvature radii are geometrically different from each other. The flat lens cannot sufficiently narrow light due to so-called astigmatism in which light is not focused on one point. Furthermore, when focusing is performed using a thin lens by increasing a height, the focal length increases, by which light cannot be narrowed. 
     A reflow lens illustrated in  FIG.  16 B  is provided as one of the solutions. 
       FIG.  16 B  is a top view of an example of the lens  72  constituted by the reflow lens. The reflow lens is characterized in that the lens material is formed into a lens shape by directly applying heat to the lens material. Regarding the reflow lens, a resin such as an acrylic resin is dissolved in a solvent, for example. In this case, for example, a material to which an ortho-naphthoquinone diazido compound is added can be used as the photosensitizer. The reflow lens is difficult to narrow the gap with respect to the method using etch back, and in particular, the gap at the diagonal portion becomes wide. On the other hand, the reflow lens has advantages that a thick lens is easily formed, the number of steps is small without requiring etch back, and the lens material of the PAD portion can be removed by exposure and development. 
     In the following,  FIGS.  17 A to  18 G  illustrate examples of embodiments of various lenses. Note that the structure illustrated in  FIG.  17 A  and the structure that includes a bank portion having light shielding properties illustrated in  FIG.  17 B  are not limited to be applied to the reflow lens, and may be applied to a lens formed by an etch back process to enhance light shielding performance. The bank portion is formed as a reflow stopper. Furthermore, these lenses may be provided with an antireflection film in consideration of a so-called λ/4n rule by forming a film of a material having a different refractive index, such as silicon oxide, on the surface of the lenses. As a specific example, silicon oxide having a refractive index of 1.47 is used as an antireflection film in a visible light region with respect to a lens material of a styrene-acrylic copolymer resin having a refractive index of 1.58. In this case, the thickness of silicon oxide is preferably 70 to 140 nm, and more preferably 90 to 120 nm. This configuration can improve sensor sensitivity and suppress a stray light component reflected on the sensor surface. 
       FIG.  17 A  shows vertical cross-sectional views of a lens formed by an etching process and a reflow lens. (a) illustrates the lens formed by the etching process, and (b) illustrates the reflow lens. The reflow lens has a greater thickness. As a result, the focal length can be made shorter than that of the lens formed by the etching process. 
       FIG.  17 B  shows vertical cross-sectional views of reflow lenses having bank portions. (a) is a vertical cross-sectional view of a reflow lens having a bank portion, (b) is a vertical cross-sectional view of a reflow lens having a filter and a bank portion, (c) is a top view of a rectangular bank portion, (d) is a top view of a rectangular bank portion in which corners at diagonal ends are removed, and (e) is a top view of a hexagonal bank portion. As illustrated in  FIG.  17 B , a bank portion  172  includes a metal film. The structures are different from the embodiment illustrated in  FIG.  16 B  in that the lens material is dammed by the bank portion  172  during a reflow process. 
     In (c), the bank is formed with a rectangular opening. As a result, a damming effect is provided in the vicinity of the center of the side of the bank portion  172 . On the other hand, the lens material may not reach the bank at the diagonal portion. In a case where the lens material does not reach the bank, the gap causes stray light, and the lens shape also varies. In (d), the bank is formed at the boundary between pixels so as to trace the shape of an ineffective region of the reflow lens  72  viewed from the top. The material of the reflow lens  72  is dammed over the entire area of the bank portion  172 , and the shape of the reflow lens  72  is stabilized. This configuration has an advantage that stray light from the gap portion can be effectively suppressed by the metal film included in the bank portion  172 . An example in which the cross-sectional result acquired by an AFM is approximated by an octagon has been described as an example, but the configuration is not limited thereto. For example, the cross-sectional result may be approximated by a rectangle having rounded corners. In (e), the pixels have a shape close to a circle, for example, a hexagonal shape, and the bank portion  172  is formed in a shape close to a circle. In this case, all the boundaries have an obtuse angle, and the density of the reflow lens having poor pattern fidelity can be increased. 
       FIG.  17 C  illustrates vertical cross-sectional view example of schematic views of reflow lenses having bank portions that include a transparent material. (a) is a vertical cross-sectional view of a reflow lens having a bank portion, (b) is a vertical cross-sectional view of a reflow lens having a filter and a bank portion, (c) is a top view of a rectangular bank portion, (d) is a top view of a rectangular bank portion in which corners at diagonal ends are removed, and (e) is a top view of a hexagonal bank portion. As illustrated in  FIG.  17 C , a bank portion  172   a  includes a transparent material. The bank portion  172   a  is inferior to the bank portion  172  illustrated in  FIG.  17 B  in light shielding property, but has an effect of suppressing sensitivity loss. In addition, stray light can be suppressed by a waveguide effect by providing a difference in refractive index between the bank portion including a transparent material and the lens material. 
       FIG.  17 D  illustrates vertical cross-sectional view examples of schematic views of reflow lenses having bank portions including a light-shielding resin, for example, a carbon black resist. (a) is a vertical cross-sectional view of a reflow lens having a bank portion, (b) is a vertical cross-sectional view of a reflow lens having, in the same layer, a bank portion including a light-shielding resin and a filter thinner than the bank portion, (c) is a vertical cross-sectional view of a reflow lens having a bank portion that includes a light-shielding resin on a filter, (d) is a top view of a rectangular bank portion, (e) is a top view of a rectangular bank portion in which corners at diagonal ends are removed, and (f) is a top view of a hexagonal bank portion. As illustrated in  FIG.  17 D , a bank portion  172   b  includes a light-shielding resin. The bank portion  172   b  is inferior to the bank portion  172  illustrated in  FIG.  17 B  in light shielding property, but can be formed with a smaller number of steps. The bank portion  172   b  is inferior to the bank portion  172   a  illustrated in  FIG.  17 C  in sensitivity, but is superior in light shielding property. 
       FIG.  18 A  is a diagram illustrating an example of a method for manufacturing a lens by an etch back process. As illustrated in  FIG.  18 A , a lens material  72   a  may be, for example, an organic material such as a styrene resin, an acrylic resin, a styrene-acrylic copolymer resin, or a siloxane resin. For example, these materials are spin coated. Alternatively, an inorganic material such as silicon nitride or silicon oxynitride may be deposited by CVD or the like. After a photosensitive resist  720   a  is applied onto the lens material  72   a , the resultant is exposed and developed, and then, heated to a temperature equal to or higher than the softening point of the resist  720   a  to form a lens shape  720   b . Thereafter, anisotropic etching is performed using a resist of the lens shape  720   b  as a mask to transfer the shape of the resist to the lens material  72   a . Thus, the lens  72  is formed. According to the etch back process described above, a gap at the lens boundary can be narrowed by adhesion of deposited materials during etching. In addition, the sensitivity can be improved by narrowing the gap. In addition, since the lens material  72   a  and silicon oxide have poor adhesion, an adhesion layer  700  may be provided under the lens material  2   a  in order to address such a problem. The adhesion layer  700  may change due to contact with metal. In view of this, a transparent inorganic film  702 , for example, silicon oxide may be provided under the adhesion layer  700 . 
       FIG.  18 B  is a diagram illustrating an example of a method for forming the reflow lens. As illustrated in  FIG.  18 B , a reflow lens material is spin-coated with a predetermined coating thickness, and then, the resultant is exposed, developed, and bleached. Then, a patterning material  72   a  having a predetermined cutout width is formed. Next, heat treatment is performed at a temperature equal to or higher than the thermal softening point of the reflow lens material, and the patterning material  72   a  is subjected to broaching by ultraviolet irradiation. As a result, the upper surface of the patterning material  72   a  is processed into a rounded shape of the on-chip lens  72 . As illustrated in  FIG.  16 B , a wide gap may be formed, and shape reproducibility may deteriorate due to variations in heat treatment. In addition, since the reflow lens material and silicon oxide have poor adhesion, an adhesion layer  700  may be provided under the reflow lens material in order to address such a problem. The adhesion layer  700  may change due to contact with metal. In view of this, a transparent inorganic film  702 , for example, silicon oxide may be formed under the adhesion layer  700 . 
       FIG.  18 C  is a diagram illustrating an example of a manufacturing method for forming a reflow lens and a reflow stopper of a bank portion including a metal film. As illustrated in  FIG.  18 C , first, a metal film  180  is deposited by CVD. Next, a resist mask  182  is formed on the metal film  180  formed on the surface by lithography. Subsequently, etching is performed using the resist mask  182  to leave the metal film  180  only at the boundary of pixels, and a metal film  184  of the reflow stopper is formed. Thus, a bank-shaped step is formed. The reflow lens may be formed by using the step due to the metal film  184  between the pixels as a stopper. 
     Thereafter, processing similar to that in  FIG.  18 B  is performed to form the on-chip lens  72  using the reflow lens. In addition, in a case where there is a concern about reliability such as a change of properties at the interface between the metal film and the reflow lens material, a transparent insulating film, for example, silicon oxide may be conformally formed by CVD, ALD, or the like. Furthermore, in a case where the adhesion is poor, a transparent material having a low viscosity and high adhesion properties such as an acrylic or epoxy resin may be spin-coated so as to leave a step, and then, the reflow lens may be formed. With the processing described above, the light shielding wall  61  and the metal film  184  of the reflow stopper can be simultaneously formed, whereby the number of steps can be reduced. It is obvious that the metal film  184  for generating the bank portion  172  is not particularly limited, and may be different from the metal film of the light shielding wall  61 . 
       FIG.  18 D  is a diagram illustrating another example of a manufacturing method for forming a reflow lens and a reflow stopper of a bank portion including a metal film. As illustrated in  FIG.  18 D , the processing in  FIG.  18 D  is different from the processing in  FIG.  18 C  in (2) and (3). That is, the metal film  180  formed on a flat surface parallel to the light receiving surface is polished and removed by CMP. Subsequently, an interlayer film including, for example, silicon oxide is made lower than the metal of the light shielding wall by wet etching using hydrofluoric acid. Thereafter, processing similar to that in  FIG.  18 C  is performed. As a result, the reflow lens can be formed on the light shielding wall in a self-alignment manner. 
       FIG.  18 E  is a diagram illustrating an example of a manufacturing method for forming a reflow lens and a reflow stopper of a bank portion including only a transparent material. As illustrated in  FIG.  18 E , after the flat metal film is removed during the formation of the light shielding wall  61 , a transparent film, for example, silicon oxide is formed by CVD. Next, a resist mask  182   a  is formed by lithography. Subsequently, etching is performed using the resist mask  182   a  to leave the transparent film as a reflow stopper  182   c  only at the boundary of pixels. Thus, a bank-shaped step is formed. Thereafter, processing similar to that in  FIG.  18 C  is performed. As a result, the bank portion  172   a  including only a transparent material can be formed as a reflow stopper. In a case where the adhesion between the reflow lens material and silicon oxide is poor, a transparent material having a low viscosity and high adhesion properties such as an acrylic or epoxy resin may be lightly spin-coated so as to leave a step, and then, the reflow lens may be formed. 
       FIG.  18 F  is a diagram illustrating an example of a method for forming a reflow lens and a bank portion including a carbon black resist. As illustrated in  FIG.  18 F , a bank portion  172   b  including a carbon black resist as a light shielding material is constituted by, for example, a photoresist composition including a carbon black dispersion, an acrylic monomer, an acrylic oligomer, a resin, a photopolymerization initiator, and the like. First, the bank portion  172   b  is formed at the boundary between pixels by photolithography. Next, a color filter  71  is formed between the bank portions  172   b . Then, the lens material  72  is formed, and heat treatment is performed to form the on-chip lens  72  that is the reflow lens, as in  FIG.  18 C . Since the distance between the light shielding wall  61  and the bank portion  172   b  can be further decreased, crosstalk between pixels can be further suppressed. Note that the color filter  71  may not be formed. In a case where the adhesion between carbon black and the silicon oxide film or between the reflow lens material and silicon oxide is poor, a transparent material having a low viscosity and high adhesion properties such as an acrylic or epoxy resin may be lightly spin-coated so as to leave a step, and then, the reflow lens may be formed. 
       FIG.  18 G  is a diagram illustrating another example of a method for forming a reflow lens and a bank portion including a carbon black resist. As illustrated in  FIG.  18 G , the method in  FIG.  18 G  is different from the method in  FIG.  18 F  in that the bank portion  172   b  including a carbon black resist is formed after the color filter  71  is formed. After the bank portion  172   b  is formed, processing similar to that in  FIG.  18 F  is performed. Since the wall of the bank portion  172   b  can be made higher than that in the formation example in  FIG.  18 F , the reflow lens can be configured to have a good thickness. 
       FIG.  19    is a schematic diagram illustrating a cross section of a pixel using the inner lens  121  and a reflow lens formed as the on-chip lens  72 .  FIG.  19    illustrates an example in which the pixel size is increased to 10 micrometers or more, for example. As illustrated in  FIG.  19   , the on-chip lens  72 , the third light shielding wall  61 C as a reflow stopper, and the first light shielding film portion  50  provided with a pinhole can be integrated with the method described in  FIGS.  17  and  18   . The configuration described above in which the on-chip lens  72  is formed as a reflow lens provides the following advantages that: the flatness of the lens is brought close to 1; the size and thickness of the lens are increased; the spot radius is reduced according to the Fraunhofer diffraction theory; the spot radius is further narrowed even by the double lens effect due to the presence of the inner lens; and the angular resolution capability of the first light shielding film portion  50  with respect to the pinhole can be improved. In addition, crosstalk between pixels is suppressed by the light shielding walls  61 A and B. Thus, the resolution can be improved, and color mixture can be suppressed. 
       FIG.  20    is a schematic diagram illustrating a cross section of a pixel using a reflow lens formed as the on-chip lens  72  without using the inner lens  121 .  FIG.  20    illustrates an example in which the pixel size is increased to 10 micrometers or more, for example. The configuration described above in which the on-chip lens  72  is formed as a reflow lens provides the following advantages that: the flatness of the lens is brought close to 1; the size and thickness of the lens are increased; the spot radius is reduced according to the Fraunhofer diffraction theory; and the angular resolution capability of the first light shielding film portion  50  with respect to the pinhole can be improved. The configuration without having the inner lens  121  can reduce the number of steps, that is, cost, although the light-collecting power of the lens relatively decreases. In addition, crosstalk between pixels is suppressed by the light shielding wall  61 A(B). Thus, the resolution can be improved, and color mixture can be suppressed. 
       FIG.  21    is a schematic diagram illustrating a cross section of a pixel using a second light shielding film portion  52  and a reflow lens formed as the on-chip lens  72 .  FIG.  21    illustrates an example in which the pixel size is increased to 10 micrometers or more, for example. The configuration described above in which the on-chip lens  72  is formed as a reflow lens provides the following advantages that: the flatness of the lens is brought close to 1; the size of the lens can be increased; the spot radius is reduced according to the Fraunhofer diffraction theory; and the angular resolution capability of the first light shielding film portion  50  with respect to the pinhole can be improved. 
     In addition, since stray light is likely to be received due to an increase in size of the pixel, it may be necessary to enhance shielding of stray light incident on the pixel. In view of this, in  FIG.  21   , the second light shielding film portion  52  provided with an opening  52   a  is formed between the first light shielding wall  61 A and the second light shielding wall  61 B. The photoelectric conversion unit PD is irradiated with incident light through the opening  52   a . The second light shielding film portion  52  can be constituted by a material having a light shielding property, for example, aluminum (Al), tungsten (W), Cu, or an alloy thereof. In addition, titanium (Ti) or titanium nitride (TiN) can also be used as underlaying metal. 
     The second light shielding film portion  52  can improve power to shield stray light by reducing the area of the opening  52   a  and the like. On the other hand, in a case where the area of the opening  52   a  and the like is reduced, an amount of shielded normal light increases, so that the sensitivity of the pixel decreases. It is desirable to design the opening  52   a  and the like in consideration of such conditions. 
     In addition, crosstalk between pixels is suppressed by the light shielding walls  61 A and B. Thus, the resolution can be improved, and color mixture can be suppressed. 
       FIG.  22    is a cross-sectional view of a finger surface. The upper side of the drawing indicates the surface of the finger.  FIG.  23    is an image of the vein of the finger captured by the imaging unit  8 . As illustrated in  FIG.  22   , the imaging unit  8  acquires fingerprint information by reading a region where the ridge of the fingerprint is present and a region where the ridge of the fingerprint is absent by each pixel. 
     The vein is located 2 millimeters from the skin surface. For example, when visible light in a red region to an infrared region is incident as imaging light, the light is absorbed in a region where the vein is present, and thus the light does not enter the corresponding pixel so much. As illustrated in  FIG.  23   , the imaging unit  8  can acquire information regarding veins by, for example, acquiring the intensity of light entering the pixel. 
     Next, a case where the pixel is configured using a diffraction lens will be described with reference to  FIGS.  24  to  28   . Using the diffraction lens as described above makes it possible to improve the measurement accuracy even in a case where the elevation angle and measurement light for a measurement target are different as in the case of imaging of a fingerprint and a vein. This will be described in more detail below. 
       FIG.  24    is a schematic diagram illustrating a cross section of a pixel using diffraction lenses D 2  and D 4  for the inner lens (second lens).  FIG.  25    is a plan view of the diffraction lenses D 2  and D 4 .  FIG.  26    is a plan view of diffraction lenses D 6  and D 8 . For example, the diffraction lenses D 2  and D 6  are for imaging fingerprints, and the diffraction lenses D 4  and D 8  are for imaging veins. 
     As illustrated in  FIG.  24   , in the present embodiment, the diffraction lenses D 2  (D 6 ) and D 4  (D 8 ) are disposed as inner lenses. The diffraction lenses D 2  and D 4  can be formed to be thinner than optical lenses, whereby the reduction in thickness of the pixel can be achieved. In addition, the diffraction lenses D 2  to D 8  make it possible to perform different pupil corrections in accordance with the imaging target and the measurement light. 
     More specifically, as illustrated in  FIGS.  25  and  26   , each of the diffraction lenses D 2  to D 8  includes a high refractive index layer D 21  having a higher refractive index and a low refractive index layer D 22  having a lower refractive index, the high refractive index layer D 21  and the low refractive index layer D 22  being alternately arranged in the lateral direction with respect to an optical axis. The width of each of the high refractive index layer D 21  and the low refractive index layer D 22  is equal to or smaller than the order of the wavelength of incident light. The degree of curvature of the equiphase surface can be adjusted by adjusting the arrangement relationship regarding densities of the high refractive index layers between the center and the ends of the diffraction wren D 2  to D 8 . As a result, a convex lens function (light-collecting properties) can be obtained, and a concave lens function (diffuseness) can be obtained. In addition, a function (oblique light correcting function) for converting obliquely incident light into normally incident light can also be obtained. 
     The convex lens function can be obtained by arranging the high refractive index layers so as to be bilaterally symmetrical in such a manner that they are densely arranged at the mechanical center of the diffraction lenses D 2  and D 4  and they are sparsely arranged with distance from the center as illustrated in  FIG.  25   . The oblique light correcting function is obtained by arranging at least one of the high refractive index layers D 21  or the low refractive index layers D 22  in such a manner that the widths thereof are asymmetric in the lateral direction as illustrated in  FIG.  26   . That is, pupil correction can be performed. In addition, for example, the diffraction lens D 8  for veins is configured to have a wider interval between the high refractive index layer D 21  and the low refractive index layer D 22  than the diffraction lens D 6  for fingerprints. With this configuration, the oblique light correcting function of the diffraction lens D 6  is higher than that of the diffraction lens D 8 . As described above, by adjusting the interval between the high refractive index layer D 21  and the low refractive index layer D 22 , it is possible to respond to the elevation angle and the measurement wavelength. 
     In a case where the size of the pixel for fingerprints is reduced by pupil correction, the angle of view increases and the resolution deteriorates because of the vein being located at a deep position of about 2 mm. However, due to the configuration in which different pupil corrections are performed by the diffraction lenses D 2  to D 8  to lower the pupil correction for the pixel for veins as described above, optimum angles of view can be achieved for the respective pixels. 
     In addition, the fingerprint is imaged with visible light, and the vein is imaged with light in a red region to an infrared region. Therefore, by adjusting the interval between the high refractive index layer D 21  and the low refractive index layer D 22 , pupil correction can be adjusted in consideration of chromatic aberration. For example, at the left end of the imaging unit  8 , the diffraction lens D 6  illustrated in  FIG.  26 ( a )  is disposed for fingerprints, and the diffraction lens D 8  illustrated in  FIG.  26 ( b )  is disposed in the adjacent pixel. In addition, the interval between the high refractive index layer D 21  and the low refractive index layer D 22  is varied corresponding to the wavelength of each of R, G, and B. 
     Here, an example in which the diffraction lenses D 4  and D 8  are arranged in a two-dimensional array of pixels in the imaging unit  8  will be described with reference to  FIG.  27   . 
       FIG.  27    is a diagram illustrating an arrangement example of the diffraction lenses D 4  and D 8  used for imaging veins. In a case where the diffraction lenses D 4  and D 8  are applied to the pixel array of the imaging unit  8 , oblique incidence is not a problem at the center of the pixel array portion, so that the oblique light correction effect is unnecessary. On the other hand, obliquely incident light incidence becomes more problematic with nearness to the end of the pixel array portion. Therefore, a degree of change in the ratio of the low refractive index layer  20  and the high refractive index layer  21  is increased toward the end of the pixel array portion so that an incident angle conversion function increases toward the end of the pixel array portion. That is, it is preferable to have a structure in which there is no asymmetry at the center of the pixel array portion and the asymmetry increases toward the end of the pixel array portion. 
     In addition, the diffraction lenses D 2  and D 6  for fingerprints are arranged so as to be adjacent to the diffraction lenses D 4  and D 8  used for imaging veins, for example. Note that the number of pixels for imaging fingerprints and the number of pixels for imaging veins may be different from each other. For example, the number of pixels for imaging fingerprints and the number of pixels for imaging veins may have a ratio of 4:1 or 8:1. Note that, in the present embodiment, the diffraction lenses D 2  to D 8  are used for the second lens, but the configuration is not limited thereto. For example, the diffraction lenses D 2  to D 8  may be used for the on-chip lens  72 . In this case, the second lens may be an optical lens or may not be provided. 
     As described above, the present embodiment includes the pixel  22  provided with the on-chip lens  72  and the first light shielding film portion  50  formed with the pinhole  50   a . With this configuration, a beam is narrowed by the on-chip lens  72 , and both the angular separation and the sensitivity can be achieved by the pinhole  50   a.    
     Second Embodiment 
     An electronic device  1  according to the second embodiment is different from the electronic device  1  according to the first embodiment in that the shape of the pinhole of the first light shielding film portion  50  can be varied for each pixel. The differences from the electronic device  1  according to the first embodiment will be described below. 
       FIGS.  28 A to  28 C  are plan views illustrating the shape of the pinhole  50   a  of the first light shielding film portion  50 .  FIG.  28 A  is a diagram illustrating a first light shielding film portion  50  having a circular pinhole  50   a .  FIG.  28 B  is a diagram illustrating the first light shielding film portion  50  having an octagonal pinhole  50   a .  FIG.  28 C  is a diagram illustrating the first light shielding film portion  50  having a rectangular pinhole  50   a.    
     As described above, the shape of the pinhole  50   a  can be selected according to the characteristics of the optical system such as the on-chip lens  72  and the inner lens  121 . For example, when the light intensity distribution of incident light by the optical system including the on-chip lens  72 , the inner lens  121 , and the like is close to a perfect circle, the circular pinhole  50   a  is selected. When the light intensity distribution is close to an octagonal shape, the octagonal pinhole  50   a  is selected. When the light intensity distribution is close to a rectangular shape, the rectangular pinhole  50   a  is selected. As a result, it is possible to improve the angular resolution capability and the sensitivity in accordance with the light intensity distribution. 
       FIG.  29    is a diagram illustrating an example in which an opening area of the pinhole shape is varied for each pixel. The opening area of a pinhole  50   b  is smaller than the opening area of a pinhole  50   c . Therefore, the angular differentiation ability of the pixel corresponding to the pinhole  50   b  is higher than the angular differentiation ability of the pixel corresponding to the pinhole  50   c . On the other hand, the sensitivity of the pixel corresponding to the pinhole  50   c  is higher than the sensitivity of the pixel corresponding to the pinhole  50   b . As described above, the angular resolution capability, that is, the resolution, and the sensitivity can be complementarily improved by mounting pinholes having different shapes and using information of the neighboring pixels. 
       FIG.  30    is a diagram illustrating examples of the shape of pinholes arranged in a two-dimensional array of pixels in the imaging unit  8 . As illustrated in  FIG.  30   , a pinhole having a shape of a perfect circle or a square shape is disposed at the central part of the two-dimensional array of pixels, and a pinhole having an elliptic shape or a rectangular shape is disposed at the peripheral part. Furthermore, the orientation of the elliptical or rectangular pinhole is adjusted according to the angle from the central part of the two-dimensional array of pixels. In this manner, it is possible to change the pinhole shape within the angle of view in accordance with the light intensity distribution on the two-dimensional array. Thus, the angular resolution capability, that is, the resolution, and the sensitivity of each pixel on the two-dimensional array can be improved. 
       FIG.  31    is a diagram illustrating examples of the shape of pinholes arranged in a one-dimensional row of the two-dimensional array of pixels in the imaging unit  8 . As illustrated in  FIG.  31   , the size of the pinhole shape is increased from the central part toward the end of the two-dimensional array of pixels, for example. In this manner, it is possible to change the size of the pinhole shape within the angle of view in each pixel in accordance with the assumed light intensity distribution on the two-dimensional array. For example, in a case where an optical lens is provided above a sensor, the sensitivity of each pixel on the two-dimensional array can be improved with respect to an increase in the spot radius depending on the angle of view caused by the inclination of a principal ray. 
       FIG.  32    is a diagram illustrating an arrangement example of pinhole shapes in a case where the outputs of respective pixels are added. As illustrated in  FIG.  32   , each of addition pixels  3   a  and  3   b  has 7 (column)×7 (row) pixels  22  ( FIG.  3   ) (49 pixels  22  in total). One side of the pixel  22  ( FIG.  3   ) is 5 micrometers, for example. Each of the addition pixels  3   a  and  3   b  adds together the outputs of a total of 49 pixels  22  ( FIG.  3   ). In this case, the size of the pinhole shape at an end  30   a  of each of the addition pixels  3   a  and  3   b  is set to be smaller than that at the central part. With this configuration, the angular resolution capability of the pixel at the end  30   a  is further improved, and the angular separation between the addition pixel  3   a  and the addition pixel  3   b  is further improved. On the other hand, the size of the pinhole shape at the central part  30   b  of each of the addition pixels  3   a  and  3   b  is set to be larger than that at the peripheral part as long as light other than light from the subject target in the addition region in which the pinhole shape belongs is not received. This further improves the sensitivity. Furthermore, since the pixel addition is performed, the crosstalk of each pixel does not become a problem. As described above, in a case where, for example, 7×7 pixels  22 , each having a side of 5 micrometers, are added in order to compensate for the insufficient sensitivity of the pinhole structure, the pinholes at the outer periphery of each of the addition pixels  3   a  and  3   b  in a block are formed to have a small opening, and the pinholes at the central part of the block are formed to have a large opening. This makes it possible to simultaneously improve the sensitivity and the resolution. 
       FIGS.  33 A and  33 B  are diagrams illustrating arrangement examples of pinhole shapes in the imaging unit  8  capable of imaging both a fingerprint and a vein.  FIG.  33 A  is a diagram illustrating the shape of a pinhole in a pixel for imaging fingerprints at the central part of the two-dimensional array of pixels in the imaging unit  8 , and the shape of a pinhole in the adjacent pixel for imaging veins. 
       FIG.  33 B  is a diagram illustrating the shape of a pinhole in a pixel for imaging fingerprints at the peripheral part of the two-dimensional array of pixels in the imaging unit  8 , and the shape of a pinhole in the adjacent pixel for imaging veins. As illustrated in  FIG.  33 A , normal incidence is assumed at the center of the pixel array, and thus, there is no difference in shape, and pinholes  50   g  and  h  are arranged at the central part. On the other hand, the pinholes  50   g  and  h  are shifted from the central part toward the end of the pixel array portion in accordance with the assumed size of the subject. In this case, the shifted positions are different between the pixel for fingerprints and the pixel for veins, because the elevation angle and the measurement wavelength are different between fingerprints and veins. That is, in the pixels adjacent to each other, the position of the pinhole  50   g  in the pixel for imaging fingerprints is further shifted from the central part than the position of the pinhole  50   h  in the pixel for imaging veins. Thus, it is possible to achieve an optimum size for the subject to be detected by each pixel. 
     Furthermore, the adjustment of pupil correction can be performed in various ways by, for example, a combination with the arrangement example of the diffraction lenses D 2  to D 8  described with reference to  FIGS.  25  to  27   . As a result, the resolution and sensitivity of each pixel can be further improved individually. 
     Here, a case where the shape within the pinhole  50   k  of the first light shielding film portion  50  is formed using a plasmon filter will be described. 
       FIG.  34    is a diagram illustrating an example in which the shape within the pinhole  50   k  of the first light shielding film portion  50  is formed using a plasmon filter. The right diagram is an enlarged view of the inside of the pinhole  50   k . As illustrated in  FIG.  34   , the plasmon filter in the pinhole  50   k  includes a plurality of holes  132 A. 
     As illustrated in  FIG.  34   , a narrow band filter by plasmon resonance on a metal surface is achieved by arranging fine hole holes  132 A having a size equal to or less than the wavelength in the pinhole  50   k . The plasmon resonance is theoretically generated when the conditions represented by Expressions (2) and (3) are satisfied where the surface plasma frequency is ωsp, the dielectric constant of a conductor thin film is εm, the dielectric constant of the interlayer film is εd, and the hole pitch is a0. 
     
       
         
           
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       FIG.  35    is a diagram illustrating a configuration example of the plasmon filter in the pinhole  50   k . The plasmon filter is constituted by a plasmon resonator in which holes  132 A are periodically arranged in a metal thin film (hereinafter, referred to as a conductor thin film)  131 A in a honeycomb shape having a high filling rate, for example. Each hole  132 A penetrates the conductor thin film  131 A and acts as a waveguide. Commonly, a waveguide has a cutoff frequency and a cutoff wavelength determined by a shape such as a side length and a diameter, and has a property of not propagating light having a frequency equal to or lower than the cutoff frequency (wavelength equal to or higher than the cutoff wavelength). The cutoff wavelength of the hole  132 A mainly depends on an opening diameter D 1 , and the cutoff wavelength becomes shorter as the opening diameter D 1  is smaller. Note that the opening diameter D 1  is set to a value smaller than the wavelength of light to be transmitted. 
     On the other hand, when light is incident on the conductor thin film  131 A in which the holes  132 A are periodically formed at a pitch equal to or less than the wavelength of light, a phenomenon occurs in which light having a wavelength longer than the cutoff wavelength of the holes  132 A is transmitted. This phenomenon is referred to as an abnormal transmission phenomenon of plasmon. This phenomenon occurs when surface plasmon is excited at the boundary between the conductor thin film  131 A and the interlayer film  102  on the conductor thin film. 
       FIG.  36    is a graph illustrating an example of spectral characteristics of the plasmon filter in the pinhole  50   k  in a case where the hole pitch P 1  is changed using aluminum as the conductor thin film. The horizontal axis of the graph represents wavelength (nm), and the vertical axis represents sensitivity (arbitrary unit). A line L 11  indicates spectral characteristics in a case where the hole pitch P 1  is set to 250 nm, a line L 12  indicates spectral characteristics when the hole pitch P 1  is set to 325 nm, and a line L 13  indicates spectral characteristics when the hole pitch P 1  is set to 500 nm. 
     In a case where the hole pitch P 1  is set to 250 nm, the plasmon filter mainly transmits light in a blue wavelength band. In a case where the hole pitch P 1  is set to 325 nm, the plasmon filter mainly transmits light in a green wavelength band. In a case where the hole pitch P 1  is set to 500 nm, the plasmon filter mainly transmits light in a red wavelength band. It is to be noted, however, that, in a case where the hole pitch P 1  is set to 500 nm, the plasmon filter also transmits a large amount of light in a band having a wavelength lower than that of red due to a waveguide mode to be described later. By providing the plasmon filter in the pinhole  50   f  in this manner, wavelength separation is also possible. In addition, since the plasmon filter is provided in the region where light is collected, the area of the plasmon filter can be downsized. Due to the decrease in size, it is possible to obtain an effect of reducing a defect rate for defects occurring with a certain probability during the wafer process. 
       FIG.  37    is a diagram illustrating spectral characteristics of the plasmon filter in a case where the hole pitch P 1  is set to 500 nm, similar to the spectral characteristics indicated by the line L 13  in  FIG.  36   . In this example, the wavelength component in the plasmon mode appears on the longer wavelength side with respect to the cutoff wavelength around 630 nm, and the wavelength component in the waveguide mode appears on the shorter wavelength side with respect to the cutoff wavelength. The cutoff wavelength mainly depends on the opening diameter D 1  of the hole  132 A, and the cutoff wavelength becomes shorter as the opening diameter D 1  is smaller. Then, as the difference between the cutoff wavelength and the peak wavelength in the plasmon mode is increased, the wavelength resolution characteristics of the plasmon filter are improved. 
     In addition, as the plasma frequency ωp of the conductor thin film  131 A increases, the surface plasma frequency ωsp of the conductor thin film  131 A increases. In addition, the surface plasma frequency ωsp increases as the dielectric constant εd of the interlayer film  102  decreases. Then, as the surface plasma frequency ωsp increases, the resonance frequency of the plasmon can be set higher, and the transmission band (resonance wavelength of the plasmon) of the plasmon filter can be set to a shorter wavelength band. 
     Therefore, when metal having a smaller plasma frequency ωp is used for the conductor thin film  131 A, the transmission band of the plasmon filter can be set to a shorter wavelength band. For example, aluminum, silver, gold, and the like are suitable. However, in a case where the transmission band is set to a long wavelength band such as infrared light, copper or the like can also be used. 
     In addition, when a dielectric having a smaller dielectric constant εd is used for the interlayer film  102 , the transmission band of the plasmon filter can be set to a shorter wavelength band. For example, SiO2, Low-K, and the like are preferable. 
     As described above, the present embodiment makes it possible to vary the shape of the pinhole  50   a  of the first light shielding film portion  50  for each pixel. This makes it possible to improve the angular resolution capability and the sensitivity of each pixel. Furthermore, in a case where the shape within the pinhole  50   k  the first light shielding film portion  50  is formed using a plasmon filter, wavelength resolution can be generated in the pinhole  50   k.    
     Third Embodiment 
     An electronic device  1  according to the third embodiment is different from the electronic device  1  according to the second embodiment in having a function of determining whether an object to be imaged is a human finger or an artificial object by processing a signal obtained by a configuration in which the shape of the pinhole  50   k  is formed using a plasmon filter. The differences from the second embodiment will be described below. 
       FIG.  38    is a block diagram schematically illustrating a part of the electronic device  1  according to the present embodiment. The electronic device  1  includes an imaging unit  8  ( FIG.  1   ), an A/D conversion unit  502 , a clamp unit  504 , a per-color output unit  506 , a defect correction unit  508 , a linear matrix unit  510 , a spectrum analysis unit  512 , an authentication unit  514 , and a result output unit  516 . In the imaging unit  8  ( FIG.  1   ), a part of the pixel is configured such that the shape of the pinhole  50   k  of the first light shielding film portion  50  is formed using a plasmon filter. As illustrated in  FIG.  36   , the plasmon filter has a hole pitch of, for example, 500 nm so as to have sensitivity having a peak around 760 nm. 
     The A/D conversion unit  502  (analog to digital converter) converts an analog signal output from the imaging unit  8  into a digital signal for each pixel. 
     The clamp unit  504  executes, for example, processing related to a ground level in the image. For example, the clamp unit  504  defines a black level, subtracts the defined black level from image data output from the A/D conversion unit  502 , and outputs the image data. The clamp unit  504  may set the ground level for each photoelectric conversion element included in the pixel, and in this case, ground correction of a signal value may be performed for each photoelectric conversion element from which the signal value is acquired. 
     In a case where the imaging unit  8  acquires an analog signal for each color, the per-color output unit  506  outputs the image data output from the clamp unit  504  for each color, for example. In the imaging unit  8 , for example, R (red), G (green), and B (blue) filters are provided in the pixel. The clamp unit  504  adjusts the ground level on the basis of these filters, and the per-color output unit  506  outputs the signal output from the clamp unit  504  for each color. 
     Since the analog signal acquired by the imaging unit  8  does not include color data, the per-color output unit  506  may, for example, store data of the hole pitch of the filter and the plasmon filter provided for each pixel in the imaging unit  8 , and perform output for each color on the basis of this data. Although the imaging unit  8  includes the color filter, the configuration is not limited thereto, and for example, a color may be identified by an organic photoelectric conversion film. 
     The defect correction unit  508  corrects a defect in the image data. The defect of the image data occurs due to, for example, a pixel defect or information loss caused by a defect of a photoelectric conversion element provided in the pixel, or due to information omission caused by saturation of light in the optical system  9 , or the like. The defect correction unit  508  may perform defect correction processing by performing interpolation processing on the basis of information of surrounding pixels or intensity of light received by surrounding photoelectric conversion elements in the pixel, for example. 
       FIG.  39    is a diagram illustrating molar extinction coefficients of reduced hemoglobin and oxygenated hemoglobin in an intravenous blood stream. The vertical axis represents a molar extinction coefficient, and the horizontal axis represents a wavelength. Veins contain a large amount of reduced hemoglobin that has lost oxygen. This reduced hemoglobin has a characteristic absorption spectrum in the vicinity of 760 nanometers as indicated in a circular frame. 
     Referring again to  FIG.  38   , the linear matrix unit  510  carries out correct color reproduction by performing matrix operation on color information such as RGB. The linear matrix unit  510  is also referred to as a color matrix unit. For example, the linear matrix unit  510  acquires desired spectroscopy by performing calculation relating to a plurality of wavelengths. In the present embodiment, the linear matrix unit  510  performs, for example, calculation so as to make an output suitable for detecting the skin color. The linear matrix unit  510  may include a calculation path of a different system from the skin color, and may, for example, perform calculation so as to make an output suitable for detection of yellow to red in order to acquire information regarding the vein. In particular, in the present embodiment, the linear matrix unit  510  may perform calculation so as to make an output suitable for the wavelength around 760 nanometers. 
     The spectrum analysis unit  512  determines, for example, whether or not there is a rise in skin color spectrum on the basis of the data output from the linear matrix unit  510 , and in a case where there is a skin color, detects the wavelength of the skin color. Skin color varies from individual to individual, but generally has a rise in a wavelength region of 550 nm to 600 nm in many cases. For this reason, the spectrum analysis unit  512  detects whether or not a human finger is in contact with the cover glass  7 , and in that case, detects the wavelength thereof, by detecting the rise of the signal in a range including 500 to 650 nm as described later, and outputs the result, for example. The determination range is not limited to the above range, and may be wider or narrower than the above range in an appropriate range. 
     In particular, in the present embodiment, whether or not there is a peak around 760 nanometers of reduced hemoglobin is analyzed. 
     The authentication unit  514  executes personal authentication on the basis of the data output from the spectrum analysis unit  512 . The authentication unit  514  executes personal authentication on the basis of, for example, a wavelength at which the rise is detected by the spectrum analysis unit  512  and a fingerprint shape (feature point) based on data output from the defect correction unit  508  and the like. In particular, in the present embodiment, the object to be imaged is determined to be an artificial object in a case where there is no peak around 760 nanometers of the reduced hemoglobin. Further, the authentication unit  514  may analyze the rhythm of the peak around 760 nanometers of the reduced hemoglobin, and determines that the object to be imaged is an artificial object in a case where the rhythm is not observed. As described above, the authentication unit  514  can enhance the biometric authentication accuracy by capturing the signal of hemoglobin, that is, the rhythm of heart rate from the blood flow. 
     Personal information may be stored in the authentication unit  514  as a wavelength range and a fingerprint feature point, or may be stored in a storage unit (not illustrated), for example. In a case where an object comes into contact with the cover glass  7 , the authentication unit  514  can determine that the object is a finger and can authenticate that the object is a stored individual. 
     In a case where the spectrum analysis unit  512  detects the rise of the wavelength related to the vein, the authentication unit  514  may further confirm that the object in contact with the cover glass  7  is a living body using this data. Furthermore, the authentication unit  514  may acquire the shape of the vein by an output from the defect correction unit  508  or the like, and use this information. As another example, the authentication unit  514  may execute authentication using vein information without using a fingerprint. 
     The result output unit  516  outputs the personal authentication result on the basis of the result output from the authentication unit  514 . For example, suppose that the result matches the individual recorded by the authentication unit  514 . In that case, the result output unit  516  outputs a signal indicating that the authentication is successful when the finger touching the cover glass  7  at that timing matches the recorded personal data, and in other cases, outputs a signal indicating that the authentication fails. 
     As described above, according to the present embodiment, a part of the pixels in the imaging unit  8  is constituted by a plasmon filter having a peak of sensitivity characteristics around 760 nanometers. It is possible to determine the presence or absence of a peak of the reduced hemoglobin around 760 nanometers with higher accuracy by performing vein authentication including the output of the pixel constituted by the plasmon filter that has sensitivity characteristics with a peak around 760 nanometers. As a result, in a case where there is no peak of the reduced hemoglobin around 760 nanometers, the authentication unit  514  can determine that the object to be imaged is an artificial object. 
     (Modification of Third Embodiment) 
     The electronic device according to the third embodiment determines whether an object to be imaged is a human finger or an artificial object by processing a signal obtained by a configuration in which the shape of the pinhole  50  is formed using a plasmon filter. An electronic device according to a modification of the third embodiment similarly processes outputs of pixels including a color filter  71  using an organic material including a pigment, a dye, or the like, for example, pixels provided with a color filter of red (R), green (G), blue (B), cyan (C), magenta (M), yellow (Y), green (G), or the like, to thereby determine whether an object to be imaged is a human finger or an artificial object. Alternatively, color filters of the same color and different film thicknesses may be provided, and a difference in a wavelength region with low transmittance may be extracted according to the Lambert-Beer law. Alternatively, the spectrum difference may be extracted by changing the content of the pigment or the dye in the color filers of the same color. 
     Fourth Embodiment 
     An electronic device according to the fourth embodiment is different from the electronic device  1  according to the third embodiment in further having a function of measuring an oxygen saturation concentration by processing a signal obtained by a configuration in which the shape of the pinhole  50  is achieved by a filter having sensitivity characteristics with peaks around 660 nanometers and around 940 nanometers, for example, a plasmon filter. The differences from the third embodiment will be described below. 
     In the imaging unit  8  ( FIG.  1   ), a part of the pixel is configured such that the shape of the pinhole  50  of the first light shielding film portion  50  is formed using a plasmon filter. The plasmon filter includes a plasmon filter having sensitivity characteristics with a peak around 660 nanometers and a plasmon filter having sensitivity characteristics with a peak around 940 nanometers. 
       FIG.  40    is a diagram illustrating molar extinction coefficients of reduced hemoglobin and oxygenated hemoglobin in a range including a region from 660 nanometers to 940 nanometers. The vertical axis represents a molar extinction coefficient, and the horizontal axis represents a wavelength. An alternate long and short dash line indicated as red light corresponds to 660 nanometers, and an alternate long and short dash line indicated as infrared light corresponds to 940 nanometers. A line indicated by no oxygen represents reduced hemoglobin, and a line indicated by having oxygen represents oxygenated hemoglobin. 
     The spectrum analysis unit  512  according to the present embodiment calculates an absorption coefficient spectrum for each wavelength of oxygenated hemoglobin and reduced hemoglobin. The authentication unit  514  (saturated oxygen concentration measuring unit) calculates the oxygen saturation concentration by a signal ratio of the difference value in absorption coefficient spectra between the oxygenated hemoglobin and the reduced hemoglobin at 660 nanometers and the difference value in absorption coefficient spectra between the oxygenated hemoglobin and the reduced hemoglobin at 940 nanometers. More specifically, the authentication unit  514  stores in advance a tape indicating the relationship between the oxygen saturation concentration corresponding to the signal ratio of the spectrum difference value between the oxygenated hemoglobin and the reduced hemoglobin at 660 nanometers and the spectrum difference between the oxygenated hemoglobin and the reduced hemoglobin at 940 nanometers. As a result, the authentication unit  514  acquires the oxygen saturation concentration corresponding to the calculated signal ratio from the table. In addition, the authentication unit  514  determines that the object to be measured is an artificial object in a case where the calculated signal ratio does not fall within a predetermined range. 
     As described above, according to the present embodiment, a part of the pixels in the imaging unit  8  is constituted by a plasmon filter having sensitivity characteristics with peaks around 660 nanometers and around 940 nanometers. With this configuration, the authentication unit  514  can acquire, with higher accuracy, the oxygen saturation concentration by a signal ratio of the spectral difference value between the oxygenated hemoglobin and the reduced hemoglobin at 660 nanometers and the spectral difference value between the oxygenated hemoglobin and the reduced hemoglobin at 940 nanometers. In addition, the authentication unit  514  can determine that the object to be measured is an artificial object in a case where the calculated signal ratio does not fall within the predetermined range. 
     (Modification of Fourth Embodiment) 
     The electronic device  1  according to the fourth embodiment determines the oxygen saturation concentration by processing a signal obtained by the configuration in which the shape of the pinhole  50  is formed using a plasmon filter. An electronic device  1  according to a modification of the fourth embodiment similarly processes outputs of pixels including a color filter  71  using an organic material including a pigment, a dye, or the like, to thereby acquire the oxygen saturation concentration. Alternatively, color filters of the same color and different film thicknesses may be provided, and a difference in a wavelength region with low transmittance may be extracted according to the Lambert-Beer law. 
     Fifth Embodiment 
     An electronic device according to the fifth embodiment is different from the fourth embodiment in further having a function of measuring a skin color by processing a signal obtained by a configuration in which the shape of the pinhole  50  is formed using a plasmon filter having sensitivity characteristics with a peak around 550 to 600 nanometers. The differences from the electronic device  1  according to the third embodiment will be described below. 
     In the imaging unit  8  ( FIG.  1   ), a part of the pixel is configured such that the shape of the pinhole  50  of the first light shielding film portion  50  is formed using a plasmon filter. The plasmon filter may include a plurality of filters having different spectra, and at least one of the plasmon filters is constituted by a plasmon filter having sensitivity characteristics with a peak around 550 to 600 nanometers. 
       FIG.  41    is a diagram illustrating reflectance of a skin surface. The vertical axis represents reflectance, and the horizontal axis represents a wavelength. As illustrated in  FIG.  41   , there is a rise in the wavelength region of 500 to 600 nanometers. Skin color varies from individual to individual, but generally has a rise in a wavelength region of 550 to 600 nanometers as described above. 
     The spectrum analysis unit  512  according to the present embodiment detects whether or not a human finger is in contact with the cover glass  7 , and in that case, detects the wavelength thereof, by detecting a rise of the signal in a range including 500 to 650 nm by signal processing of a plurality of outputs having different spectra, and outputs the result, for example. 
     The authentication unit  514  according to the present embodiment determines, on the basis of the data output from the spectrum analysis unit  512 , that the object to be imaged is a person in a case where there is a rise in the wavelength region of 500 to 600 nanometers, and that the object to be imaged is an artificial object when there is no rise in the wavelength region. 
       FIG.  42    is a flowchart illustrating an example of a flow of processing performed by the electronic device  1  according to the present embodiment. As an example, a case where the electronic device  1  performs personal authentication using fingerprint will be described. The same applies to a case where recognition is executed for a vein or the like. 
     First, the electronic device  1  activates the imaging unit  8  as a fingerprint sensor (S 100 ). Due to the start-up, the components described above may be energized to be in a standby state, for example. The electronic device  1  may explicitly activate the fingerprint sensor by a switch or the like. As another example, contact of an object on a reading surface (cover glass)  7  may be optically or mechanically acquired, and the fingerprint sensor may be activated using the acquisition as a trigger. As yet another example, the fingerprint sensor may be triggered by detecting the approach of a finger to the reading surface (cover glass)  7  by a distance shorter than a predetermined distance. 
     Next, the imaging unit  8  detects the intensity of light incident at that timing, and acquires the condition of external light on the basis of the result (S 102 ). For example, the electronic device  1  acquires an image in a state where light from the inside is not incident. With this acquisition, the intensity of sunlight, the intensity of light transmitted through the finger from an indoor light source, or the intensity of stray light entering through the gap between the fingers is detected. On the basis of the intensity of light, the clamp unit  504  may execute ground processing in a later process. 
     Next, the light emitting unit provided in the electronic device  1  emits light to irradiate at least a part of the region where the finger and the cover glass  7  are in contact with each other (S 104 ). White light may be emitted, or light having a specific wavelength, for example, light of R, G, B, or the like, may be emitted. For example, B (and G) light may be emitted in order to acquire the surface shape, because the light on the long wavelength side is transmitted through the finger. In addition, infrared light may also be emitted to observe the veins. R light may be emitted for spectral analysis. In this manner, light of an appropriate color may be emitted on the basis of the subsequent processes. These kinds of light do not need to be emitted at the same timing. For example, R light may be emitted first to acquire data for spectral analysis, and then B light and G light may be emitted to acquire, for example, data for shape analysis. 
     Next, the imaging unit  8  receives light emitted from the light emitting unit, reflected by the cover glass  7 , and including information regarding fingerprints, and the like (S 106 ). The light is received by the imaging unit  8  described above, and then, necessary processes are executed. For example, following the light reception, processing of acquiring the shape of the fingerprint and acquiring the spectrum of the reflected light or the transmitted light is executed through A/D conversion and background correction. 
     Next, the authentication unit  514  determines whether or not the fingerprint shapes match (S 108 ). The fingerprint shape may be determined by a common method. For example, the authentication unit  514  extracts a predetermined number of feature points from the fingerprint, compares the extracted feature points, and determines whether or not the object is a stored individual. 
     When the fingerprint shapes do not match (S 108 : NO), the processes from S 102  are repeated. 
     When the fingerprint shapes match (S 108 : YES), the authentication unit  514  subsequently determines whether or not the spectra match (S 110 ). The authentication unit  514  determines whether or not the spectra match by comparing the result of the spectrum analyzed by the spectrum analysis unit  512  with the stored result of the individual. For example, the determination is performed on the basis of whether or not the acquired spectrum is present within an allowable range from the stored spectrum of the rising of the skin color. In this way, the personal authentication may be performed or whether or not the object is a living body may be determined, using not only the fingerprint shape but also the spectrum. In addition, the state of the vein may be acquired in order to determine whether or not the object is a living body. In this case, infrared light is emitted from the light emitting unit, and a spectrum indicating the state of the vein is acquired and analyzed. In the case of determining whether or not the object is a living body, whether or not the spectrum indicating the vein has been acquired may be determined without acquiring the shape of the vein. Alternatively, the shape of the vein may also be acquired, and the comparison may be performed regarding the state of the vein for performing personal authentication. 
     When the spectra do not match (S 110 : NO), the processes from S 102  are repeated. 
     When the spectrum is located (S 110 : YES), the authentication unit  514  determines that the authentication is successful (S 112 ), and outputs the authentication result from the result output unit  516 . In this case, the result output unit  516  outputs information indicating that the authentication is successful, and permits access to another configuration of the electronic device  1 , for example. Note that, in the above description, the result output unit  516  makes an output in a case where the authentication is successful, but the configuration is not limited thereto. Even in a case where the determination in S 108  described above is NO and the determination in S 110  described above is NO, the information indicating that the authentication has failed may be provided to the light emitting unit, the imaging unit  8 , or the like using the result output unit  516 , and the data may be acquired again. 
     Note that, in the above description, the above processing is repeated in a case where the authentication fails. On the other hand, in a case where, for example, the processing is repeated a predetermined number of times, an access to the electronic device  1  may be blocked without performing the authentication any more. In this case, the user may be prompted to use another access means, such as an input of a passcode using a numeric keypad, from an interface. Furthermore, in such a case, a possibility of a failure of the device in reading is considered, and thus the authentication process may be repeated while changing the light emission, the light reception, the state of the reading surface, the spectrum being used, and the like. For example, in a case where an analysis result indicating that the device is wet with water is obtained, some output may be provided to the user via the interface to promote the user to wipe the water and perform the authentication operation again. 
     As described above, according to the present embodiment, a part of the pixels in the imaging unit  8  is constituted by a plasmon filter having sensitivity characteristics with a peak around 550 to 600 nanometers. As a result, the spectrum analysis unit  512  can detect the rise of a signal in a range including 500 to 650 nanometers with higher accuracy, for example. In addition, the authentication unit  514  can determine that the object to be measured is an artificial object in a case where there is no rise of the signal within the range including 500 to 650 nanometers. 
     (Modification of Fifth Embodiment) 
     The electronic device  1  according to the fifth embodiment determines the rise of a signal within a wavelength range including 500 to 650 nanometers by processing a signal obtained by the configuration in which the shape of the pinhole  50  is formed using a plasmon filter. An electronic device  1  according to a modification of the fifth embodiment similarly processes outputs of pixels including a color filter  71  using an organic material including a pigment, a dye, or the like, for example, pixels provided with a color filter of red (R), green (G), blue (B), cyan (C), magenta (M), yellow (Y), green (G), or the like, to thereby determine a rise of a signal within a range including 500 to 650 nanometers. Alternatively, color filters of the same color and different film thicknesses may be provided, and a difference in a wavelength region with low transmittance may be extracted according to the Lambert-Beer law. Alternatively, the spectrum difference may be extracted by changing the content of the pigment or the dye in the color filers of the same color. 
     Sixth Embodiment 
     An electronic device according to the sixth embodiment is different from the fifth embodiment in that pupil correction can be performed by shifting the center position of the on-chip lens  72  and the center position of the inner lens  121  with respect to the pinhole  50   a . The differences from the electronic device according to the fifth embodiment will be described below. 
     First, a configuration example of a pixel in which the center position of the on-chip lens  72  and the position of the pinhole  50   a  are shifted will be described with reference to  FIGS.  43 A and  43 B . 
       FIG.  43 A  is a schematic diagram illustrating a cross section of a pixel at the central part of the pixel array of the imaging unit  8  ( FIG.  1   ). This pixel is an example of a pixel in which the on-chip lens  72  is formed on the color filter  71  without using the inner lens  121 . This pixel is located at the central part, and thus, the center position of the on-chip lens  72  and the position of the pinhole  50   a  coincide with each other. In this case, crosstalk between pixels is also suppressed by the light shielding walls  61 A(B). Thus, the resolution can be improved, and color mixture can be suppressed. 
       FIG.  43 B  is a diagram illustrating an example in which the on-chip lens  72 , the color filter  71 , and the inner lens  121  are arranged to be shifted toward the peripheral side of the pixel array. In the peripheral part (outer peripheral part) of the pixel array of the imaging unit  8  ( FIG.  1   ), pupil correction is possible by arranging the on-chip lens  72 , the color filter  71 , and the inner lens  121  to be shifted in correspondence with the assumed angle with respect to subjects with different image heights and height positions of the subjects. These components are designed such that the light intensity distribution is concentrated in the pinhole  50   a  of the first light shielding film portion  50 , and the pinhole  50   a  is desirably disposed at the center of the photoelectric conversion element PD, but may be shifted. 
     Along with the shift of the color filter  71  and the on-chip lens  72 , the positions of the first light shielding wall  61 A and the second light shielding wall  61 B also shift to the peripheral side toward the outer periphery of the pixel array. Thus, the light shielding walls  61 A and B can suppress crosstalk between pixels, improve resolution, and suppress color mixture. As described above, shielding of a stray light component can be increased by providing the light shielding walls  61 A and B in at least two or more stages. Note that the pixel structure illustrated in  FIG.  43 B  is an example in which the light shielding wall  61  includes two stages of the first light shielding wall  61 A and the second light shielding wall  61 B. However, the pixel structure can include light shielding walls in any number of stages. The layer in which the light shielding wall  61  is formed may sometimes be referred to as a light shielding wall layer. 
       FIG.  43 C  is a diagram illustrating an example in which the on-chip lens  72 , the color filter  71 , and the inner lens  121  are arranged to be further shifted from the center side of the pixel array than the example in  FIG.  43 B . A second light shielding film portion  52 A is provided in a gap generated between the first light shielding wall  61 A and the second light shielding wall B. With this configuration, stray light leaking from between the first light shielding wall  61 A and the second light shielding wall B can be suppressed. Thus, the resolution can be improved, and color mixture can be suppressed. In this case, crosstalk between pixels is also suppressed by the light shielding walls  61 A and B. Thus, the resolution can be improved, and color mixture can be suppressed. In this manner, a degree of freedom of pupil correction can be improved while maintaining light shielding properties. 
     Next, a configuration example of a pixel in which the center position of the on-chip lens  72  and the position of the pinhole  50   a  are shifted will be described with reference to  FIGS.  44 A to  44 C . 
       FIG.  44 A  is a diagram illustrating an example in which the second light shielding film portion  52  is provided below the inner lens  121 . An opening  52   a  is provided in the second light shielding film portion  52 , whereby the second light shielding film portion  52  also has a diaphragm effect. In this case, the opening  52   a  of the second light shielding film portion  52  and the pinhole  50   a  of the first light shielding film portion  50  are arranged corresponding to the assumed angle with respect to subjects with different image heights. In addition, the area of the opening  52   a  is larger than the area of the pinhole  50   a . As described above, the second light shielding film portion  52  shields stray light from other pixels, and has a diaphragm effect for the subject pixel. This improves the resolution of the pixel. 
       FIG.  44 B  is a diagram illustrating an example in which a third light shielding film portion  54  is provided below the color filter  71 . An opening  54   a  is provided in the third light shielding film portion  54 , whereby the third light shielding film portion  54  also has a diaphragm effect. In this case, the opening  54   a  of the third light shielding film portion  54  and the pinhole  50   a  of the first light shielding film portion  50  are arranged corresponding to the assumed angle with respect to subjects with different image heights. In addition, the area of the opening  54   a  is larger than the area of the pinhole  50   a.    
     The third light shielding film portion  54  can be constituted by a material having light shielding properties, for example, aluminum (Al), tungsten (W), Cu, or an alloy thereof. In addition, titanium (Ti) or titanium nitride (TiN) can also be used as underlaying metal. As described above, the third light shielding film portion  54  shields stray light from other pixels, and has a diaphragm effect for the subject pixel. This further improves the resolution of the pixel. 
       FIG.  44 C  is a diagram illustrating an example in which the second light shielding film portion  52  is provided below the inner lens  121  and the third light shielding film portion  54  is provided below the color filter  71 . In this case, the opening  54   a  of the third light shielding film portion  54 , the opening  52   a  of the second light shielding film portion  52 , and the pinhole  50   a  of the first light shielding film portion  50  are arranged corresponding to the assumed angle with respect to subjects with different image heights. The third light shielding film portion  54  and the second light shielding film portion  52  shield stray light from other pixels, and has a diaphragm effect for the subject pixel. As described above, stray light can be shielded by a three-stage diaphragm, whereby the resolution of the pixel can be further improved. 
     Next, an arrangement example of the color filters  71  in the pixel array of the imaging unit  8  ( FIG.  1   ) will be described.  FIG.  45    is a diagram illustrating an arrangement example of the color filters  71  of red (R), green (G), and blue (B). As illustrated in  FIG.  45   , color filters  71  of red (R), green (G), and blue (B) are arranged in four adjacent pixels in, for example, the Bayer arrangement. Although only four pixels are denoted by reference signs in the drawing, color filters  71  of red (R), green (G), and blue (B) are similarly arranged in other pixels. Note that, although the present embodiment has described an example in which the Bayer arrangement is used, the configuration is not limited thereto. Furthermore, pixels using a plasmon filter may be mixed in the arrangement of the red (R), green (G), and blue (B) color filters  71 . 
       FIG.  46    is a diagram illustrating wavelength characteristics of the color filters  71  of red (R), green (G), and blue (B). The horizontal axis represents wavelength, and the vertical axis represents relative sensitivity. As illustrated in  FIG.  46   , the red (R), green (G), and blue (B) filters mainly transmit light in the red, green, and blue wavelength bands, respectively. 
     Next, an arrangement example of the complementary color filters  71  in the pixel array of the imaging unit  8  ( FIG.  1   ) will be described.  FIG.  47    is a diagram illustrating an arrangement example of the color filters  71  of cyan (C), magenta (M), yellow (Y), and green (G). As illustrated in  FIG.  44   , color filters  71  of cyan (C), magenta (M), yellow (Y), and green (G) are arranged in four adjacent pixels. Although only four pixels are denoted by reference signs in the drawing, color filters  71  of cyan (C), magenta (M), yellow (Y), and green (G) are similarly arranged in other pixels. Note that the arrangement example is not limited thereto. Furthermore, pixels using a plasmon filter may be mixed in the arrangement of the color filters  71  of an (C), magenta (M), yellow (Y), and green (G). 
       FIG.  48    is a diagram illustrating wavelength characteristics of the color filters  71  of cyan (C), magenta (M), yellow (Y), and green (G). The horizontal axis represents wavelength, and the vertical axis represents relative sensitivity. As illustrated in  FIG.  45   , the cyan (C), magenta (M), yellow (Y), and green (G) filters mainly transmit light in wavelength bands of complementary colors of red, green, and blue, respectively. 
     As described above, according to the present embodiment, pupil correction is enabled by shifting the center position of the on-chip lens  72  and the position of the pinhole  50   a . Furthermore, due to the configuration in which at least one of the second light shielding film portion  52  or the third light shielding film portion  54  is provided, stray light can be shielded by the multi-stage diaphragm, and the resolution of the pixel can be further improved. 
     Seventh Embodiment 
     An electronic device  1  according to the seventh embodiment is different from the electronic device according to the sixth embodiment in that an antireflection portion (moth-eye)  63  and a reflection film  65  are provided in the pixel  22  of the imaging unit  8  ( FIG.  1   ). The differences from the electronic device  1  according to the sixth embodiment will be described below. 
       FIG.  49    is a schematic diagram illustrating a cross section of a pixel provided with the antireflection portion (moth-eye)  63  and the reflection film  65 . As illustrated in  FIG.  49   , a surface (plate surface) of the semiconductor substrate  12  on the light entrance side has an antireflection structure including fine protrusions, a so-called moth-eye structure. At the interface of the semiconductor substrate  12 , the refractive index difference is relatively larger than that at the interface of another layered structure, and a loss of light generated by reflection of light is great. In view of this, the pixel according to the present embodiment has an antireflection structure including a group of fine protrusions on the surface of the semiconductor substrate  12  on the light entrance side. The antireflection portion  63  has not only an effect of preventing reflection but also an effect of increasing the effective optical path length by diffraction. As described above, the antireflection portion (moth-eye)  63  is formed which is a structure including protrusions and recesses arranged at a predetermined pitch on the surface on the photoelectric conversion element side. 
     Furthermore, the reflection film  65  may be formed in the interlayer insulating film  14  on the surface of the semiconductor substrate  12  opposite to the light entrance side. The reflection film  65  is, for example, a metal film, a multilayer film including a high refractive index layer and a low refractive index layer, or the like. The reflection film  65  reflects light that has passed through the semiconductor substrate  12 . 
     The first light shielding wall  61 A suppresses crosstalk, which is increased in an oblique direction due to diffraction by the moth-eye structure, between pixels in the substrate. The second light shielding wall  61 B suppresses crosstalk between pixels generated above the pinhole, and also suppresses flare. 
     As described above, according to the present embodiment, light entering the pinhole  50   a  is reciprocated in the photoelectric conversion element PD by the antireflection portion (moth-eye)  63  and the reflection film  65 , whereby the sensitivity of the pixel can be improved. 
     Eighth Embodiment 
     An electronic device  1  according to the present embodiment is different from the electronic device according to the seventh embodiment in that a phase detection pixel is included in the pixels of the imaging unit  8  ( FIG.  1   ). The differences from the electronic device  1  according to the seventh embodiment will be described below. 
     An example in which the phase detection pixel is included in the pixels of the imaging unit  8  ( FIG.  1   ) will be described. The fingerprint is imaged in a contact manner in which the finger is placed on the cover glass  7  ( FIG.  1   ), and thus, the focal length can be kept constant. Therefore, focusing is achieved without using the phase detection pixel. The present embodiment describes a case where a pixel having the pinhole  50  is used for closeup imaging in a non-contact manner or a case where an optical lens is provided will be described. For example, a case where the pixel is used for macrophotography (image capture of insects), iris identification, reading of micro barcode, or the like will be described. 
       FIG.  50    is a schematic cross-sectional view obtained by cutting out a part of the pixel array in the imaging unit  8 . The upper diagram illustrates a cross section of the pixel, and the lower diagram is a plan view of the first light shielding film portion  50 . As illustrated in  FIG.  50   , each pixel is provided with a pinhole  50   a , a right opening  50 R, or a left opening  50 L. In a case where the vertical edge of the subject is captured, the sensitivity of the phase detection pixel can be improved by forming a vertically long slit opening, and resolution can be improved by forming a laterally long and thin slit opening. 
     As illustrated in  FIG.  50   , there are two types which are a left opening  50 L formed by opening the left side with respect to the light receiving surface of the photoelectric conversion element PD ( FIG.  4   ) and a right opening  50 R formed by opening the right side, and these two types are paired and arranged at a predetermined position of the pixel array. An image shift occurs between a pixel signal from the left opening  50 L and a pixel signal from the right opening  50 R due to a difference in the formation position of the openings. A phase shift amount can be calculated from the shift of the image to calculate a defocus amount. 
       FIG.  51    is a diagram illustrating outputs of pixels having the right openings  50 R and outputs of pixels having the left openings  50 L for one column of the imaging unit  8 . The vertical axis represents an output, and the horizontal axis represents the position (address) of the pixel. As illustrated in  FIG.  51   , an image shift occurs between pixel signals from the left openings  50 L and pixel signals from the right openings  50 R due to a difference in the formation position of the openings. A phase shift amount can be calculated from the shift of the image to calculate a defocus amount. 
     As described above, in the electronic device  1  according to the present embodiment, the phase detection pixel is included in the pixels of the imaging unit  8  ( FIG.  1   ). Thus, in a case where an optical lens is combined, the focus adjustment can be performed using information regarding the phase difference, and in a case where an optical lens is not used, the resolution can be recovered by signal processing correction described later. 
     Ninth Embodiment 
     An electronic device  1  according to the ninth embodiment is different from the electronic device  1  according to the eighth embodiment in further including a process of restoring the resolution of an image by image processing using a point spread function corresponding to the pinhole  50   a . The differences from the electronic device  1  according to the eighth embodiment will be described below. 
       FIG.  52    is a block diagram schematically illustrating a part of the electronic device  1  according to the present embodiment. The electronic device  1  further includes an image processing unit  518 . 
       FIG.  53    is a diagram for describing an example of processing performed by the image processing unit  518 . M 2  is an original image, M 4  is a point spread function corresponding to, for example, the pinhole  50   a  in  FIG.  50   , and M 6  is a captured image captured by the imaging  8  via the pinhole  50   a . M 2  is an original image, M 4  is a point spread function corresponding to the pinhole  50   a , and M 4  is a captured image captured by the imaging  8  via the pinhole  50   a . The point spread function corresponding to the pinhole  50   a  can be calculated by calculating a light receiving angle distribution of the sensor or by simulation, and converting the calculated result into a beam blur in consideration of the distance to the subject. 
     F 4  is a Fourier transformed image of the point spread function M 4 , and F 6  is a Fourier transformed image of the captured image M 6 . 
     The image processing unit  518  performs, for example, recalculation using the Fourier transformed image F 6  and the Fourier transformed image F 4  to generate a Fourier transformed image F 2 . Then, the image processing unit  518  inversely transforms the Fourier transformed image F 2  to generate an original image. 
     As described above, in the electronic device  1  according to the present embodiment, the image processing unit  518  generates the Fourier transformed image F 2  of the original image M 2  using the Fourier transformed image F 4  of the point spread funk of the pinhole  50   a  and the Fourier transformed image F 6  of the captured image M 2 . Then, the original image is generated by inversely transforming the Fourier transformed image F 2 . The original image M 2  having higher resolution can be generated from the captured image M 6  using the point spread function corresponding to the pinhole  50   a.    
     Tenth Embodiment 
     An electronic device  1  according to the tenth embodiment is different from the electronic device  1  according to the ninth embodiment in that the imaging unit  8  further has a function of driving a global shutter. The differences from the electronic device  1  according to the ninth embodiment will be described below. 
       FIG.  54    is a circuit diagram illustrating a configuration example of the pixel  22 . As illustrated in  FIG.  54   , the pixel  22  includes a photoelectric conversion unit  51 , a first transfer transistor  552 , a second transfer transistor  53 , a charge holding unit  554 , an FD  55 , an amplification transistor  56 , a selection transistor  57 , and a reset transistor  58 . The photoelectric conversion unit  51  receives light that is emitted to the pixel  22 , and generates and accumulates charges corresponding to an amount of the light. The first transfer transistor  552  is driven in accordance with a transfer signal supplied from a vertical drive unit (not illustrated), and when the first transfer transistor  552  is turned on, the charge accumulated in the photoelectric conversion unit  51  is transferred to the charge holding unit  554 . 
     The second transfer transistor  53  is driven in accordance with the transfer signal, and when the second transfer transistor  53  is turned on, the charge accumulated in the charge holding unit  554  is transferred to the FD  55 . The charge holding unit  554  accumulates the charge transferred from the photoelectric conversion unit  51  via the first transfer transistor  552 . The FD  55  is a floating diffusion region having a predetermined capacitance formed at a connection point between the second transfer transistor  53  and a gate electrode of the amplification transistor  56 , and accumulates the charge transferred from the charge holding unit  554  via the second transfer transistor  53 . 
     The amplification transistor  56  is connected to a power supply VDD (not illustrated), and outputs a pixel signal at a level corresponding to the charge accumulated in the FD  55 . The selection transistor  57  is driven in accordance with a selection signal supplied from the vertical drive unit  33 , and when the selection transistor  57  is turned on, the pixel signal output from the amplification transistor  56  can be read to a vertical signal line  43  via the selection transistor  57 . 
     The reset transistor  58  is driven in accordance with a reset signal supplied from the vertical drive unit  33 , and when the reset transistor  58  is turned on, the charge accumulated in the FD  55  is discharged to the power supply VDD via the reset transistor  58 , and the FD  55  is reset. 
     The imaging unit  8  including the pixel  22  configured as described above employs a global shutter system, whereby the charges can be simultaneously transferred from the photoelectric conversion unit  51  to the charge holding unit  554  for all the pixels  22 , and the exposure timings of all the pixels  22  can be set to be the same. As a result, it is possible to avoid occurrence of distortion and blurring in the image. By suppressing distortion and blurring, the accuracy of authentication of fingerprints can be enhanced. 
       FIG.  55    is a schematic cross-sectional view of the pixel  22  that can be driven by the global shutter system. 
     As illustrated in  FIG.  55   , an embedded portion  76  is formed in the pixel  22 . The light shielding portion (embedded portion)  76  is formed to a predetermined depth so as to extend in a direction substantially orthogonal to the first shielding film  50 . The embedded portion  76  includes a material such as tungsten (W), aluminum (Al), or copper (Cu). As described above, the region where the charge holding unit (MEM)  54 , the FD  55 , and the like are formed is surrounded by the first shielding film  50  and the embedded portion  76  and is shielded from light. 
     As described above, according to the present embodiment, the pixel  22  includes the photoelectric conversion unit  51  that receives incident light through the pinhole  50   a  and the charge holding unit  554  that is surrounded by the first shielding film  50  and the embedded portion  76  and that is shielded from light. With this configuration, charges can be transferred from the photoelectric conversion unit  51  that receives incident light via the pinhole  50   a  to the charge holding unit  554 , and the exposure timings of all the pixels  22  that perform imaging via the pinholes  50   a  can be set to be the same. 
     Eleventh Embodiment 
     An electronic device  1  according to the eleventh embodiment is different from the electronic device  1  according to the tenth embodiment in that a polarizing element is included in the pixels constituting the imaging unit  8 . 
       FIG.  56 ( a )  illustrates a state in which the fingerprint is brought into contact with the cover glass of the display surface. An air layer is formed in the recessed portion of the fingerprint, and total reflection is likely to occur due to a difference in refractive index between the cover glass and the fingerprint. Thus, a contrast corresponding to the unevenness of the fingerprint is formed. In the specular reflection, polarized light in which an electric field vector vibrates in a direction perpendicular to the incident surface is likely to be specifically reflected. 
     On the other hand, as illustrated in  FIG.  56 ( b ) , we have succeeded in developing a solid-state imaging element equipped with a wire grid type polarizer. The transmission axis of the polarized light can be controlled by changing the orientation of the wire grid, and a diffusion component and a specular reflection component can be separated and analyzed by sampling several different polarization orientations and performing trigonometric function fitting. 
     In the present embodiment, assuming that light emitted by an OLED is totally reflected, uniform pupil correction is applied to all the pixels so as to detect a specific angle. Ideally, the specific angle is desirably around 57 degrees that is the Brewster&#39;s angle. However, since a total reflection mode occurs in the light collecting structure and the light collecting efficiency is deteriorated, the specific angle may be 30 degrees or more at which the difference between the S polarization and the P polarization starts to occur. Here, uniform pupil correction is applied for the sake of simplicity, but pupil correction according to the image height may be added in a direction toward the peripheral part of the chip in order to simultaneously achieve the shrink in chip size described above. 
       FIG.  57    is a cross-sectional view of a pixel  22  including a polarizer  160  provided in the pixel constituting the imaging unit  8 . As illustrated in  FIG.  57   , the polarizer can be formed independently of the pinhole, but can be integrated by forming a wire grid type polarizer in the pinhole opening. 
     The polarizer  160  can improve the contrast by arranging a plurality of different polarization orientations for the specular reflection generated at the valley and the diffused light generated at the ridge and performing component separation by the above-described trigonometric fitting. In addition, all the transmission axes of the polarizers  160  can be aligned with S-polarized light to allow the specular reflection component to be easily detected. 
       FIG.  58    is a diagram illustrating a configuration example of the polarizing unit  160 . As illustrated in  FIG.  58   , in the polarizing unit  160 , a plurality of strip-shaped conductors  161  is arranged at an equal pitch. The strip-shaped conductor  161  includes a plurality of layers. More specifically, the strip-shaped conductor  161  includes a light reflecting layer  162 , an insulating layer  163 , and a light absorbing layer  164 . 
     The light reflecting layer  162  reflects incident light. The strip-shaped conductor  161  is configured using the light reflecting layer  162 . As a result, light in a direction perpendicular to the arrangement direction of the strip-shaped conductors  161 , that is, in a vibration direction parallel to the longitudinal direction of the strip-shaped conductors  161  can be reflected. The light reflecting layer  162  includes, for example, Al. The light absorbing layer  164  absorbs light. That is, the light absorbing layer  164  absorbs the light reflected by the light reflecting layer  162 . Providing the light absorbing layer  164  can decrease reflected light from the polarizing unit  160 . As a result, noise such as flare caused by reflected light can be reduced. The light absorbing layer  164  includes a material having an extinction coefficient of not 0, that is, metal or a semiconductor having an absorption function. The light absorbing layer  164  includes, for example, a metal material such as Ag, Au, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, Ge, Te, and Sn, or an alloy containing these metal materials. 
     The light absorbing layer  164  is formed as a relatively thin film of, for example, 50 nanometers. This suppresses a reduction in transmittance when incident light is transmitted through the polarizing unit  160 . The insulating layer  163  is disposed between the light reflecting layer  162  and the light absorbing layer  164 , and protects the previously formed light reflecting layer  162 . More specifically, the insulating layer  163  is formed to have a film pressure at which the phase of light transmitted through the light absorbing layer  164  and reflected by the light reflecting layer  162  and the phase of light reflected by the light absorbing layer  164  are different from each other by 180 degrees. As a result, the light reflected by the light absorbing layer  164  and the light reflecting layer  162  cancel each other out, so that the reflection of the incident light from the polarizing unit  160  is reduced. The insulating layer  163  includes, for example, SiO 2  formed by ALD. 
     Next, a processing example using the output of a polarization pixel  100  will be described. In this example, the polarizer and the pinhole do not necessarily need to be combined in the same pixel, and processing can be performed by a pixel including only the polarizer. The A/D conversion unit  502  illustrated in  FIG.  52    outputs polarization information data obtained by digitizing the output values of a plurality of polarization pixels  100  and digital pixel data obtained by digitizing the output values of a plurality of pixels  22  which are non-polarization pixels. Next, the image processing unit  518  determines whether or not flare or diffraction has occurred on the basis of the polarization information data. When, for example, the polarization information data exceeds a predetermined threshold value, the image processing unit  518  determines that flare or diffraction has occurred. When determining that flare or diffraction has occurred, the image processing unit  518  extracts a correction amount of the flare component or the diffracted light component on the basis of the polarization information data. Then, the image processing unit  518  subtracts the correction amount from the digital pixel data to generate digital pixel data from which the flare component and the diffracted light component have been removed. 
     As described above, the present embodiment has described the electronic device that improves contrast by mounting the polarizer  180  on the normal pixel  22  constituting the imaging unit  8 . Furthermore, the flare component and the diffraction component can be removed by adding a pixel having a pinhole that is mounted with a polarizer or a pixel having only a polarizer. 
     Twelfth Embodiment 
     An electronic device  1  according to the twelfth embodiment is different from the electronic devices  1  according to the first to eleventh embodiments in having a function of changing a region of a display unit  4  that emits light according to the position of a finger placed on the cover glass  7  ( FIG.  1   ). The differences from the electronic devices  1  according to the first to eleventh embodiments will be described below. 
       FIG.  59    is a block diagram schematically illustrating a part of the electronic device  1  according to the twelfth embodiment. The electronic device  1  further includes an analysis unit  520 . 
       FIG.  60    is a diagram illustrating an example of processing performed by the analysis unit  520 . The electronic device  1  illustrated in  FIG.  60    emits light from a display panel  4  of a display unit  2  provided inside the electronic device to a reading surface, and receives returned light by an imaging element  8 . A region  590  in (a) of  FIG.  60    is an example of a fingerprint reading region. 
     The analysis unit  520  analyzes the region where the finger is placed on the basis of a signal including position information output from a touch panel  5 . Then, the analysis unit  520  controls the display panel  4  so as to narrow a light emission area only to a region around the region where the finger is placed, for example. A region  590   a  in (b) of  FIG.  60    indicates a light emitting region  590   a  with a reduced light emission area. As illustrated in (c) of  FIG.  60   , the recognition rate during the measurement of the shape of a fingerprint is improved by receiving a total reflection component due to a difference in refractive index between the cover glass  7  and the air layer. 
     Therefore, the analysis unit  520  controls the light emission area of the display panel  4  so as to receive the total reflection component from the finger. In addition, when, for example, failing in the first authentication, the analysis unit  520  may correct the light emission area on the basis of information regarding the contour of the finger in the first authentication. 
     In addition, the analysis unit  520  may guide and display the contact region of the finger on the reading surface on the display panel  4  so as to satisfy, for example, the condition that the light obtained by totally reflecting light from the light source by the reading surface can be received by the imaging element. Furthermore, the analysis unit  520  may acquire information regarding the spectrum unique to human skin by decomposing, by the imaging element, the wavelength of light that is diffused and propagated into the finger from, for example, a region where the ridge of the fingerprint and the reading surface  12  are in contact with each other and that is returned to the electronic device side again. Alternatively, the analysis unit  520  may use the fact that light in the red region to the near-infrared region is more likely to be absorbed in a region in which a vein or an artery exists than in a region in which no blood exists to thereby acquire spectral information regarding the vein or the artery (and shape). 
     As described above, in the electronic device  1  according to the present embodiment, the analysis unit  520  analyzes the position of the finger to change the light emitting region  590   a  of the display panel  4 . As a result, the total reflection component from the fingerprint region can be received more, and the fingerprint recognition rate is further improved. 
     Thirteenth Embodiment 
     An electronic device  1  according to the thirteenth embodiment is different from the electronic devices  1  according to the first to twelfth embodiments in further having a light source  600  different from the display unit  2 . The differences from the electronic devices  1  according to the first to twelfth embodiments will be described below. 
       FIG.  61    is a diagram illustrating an arrangement example of the light source  600 . The electronic device  1  illustrated in (a) includes the light source  600  different from the display unit  2  in a housing of the electronic device. Light is emitted from the light source  600  toward the reading surface  590 , and the returned light is received by the imaging element  8 . The imaging element  8  may be disposed under a display (not illustrated) of a smartphone, or the like, or may be arranged in a region not under the display, for example, a region of a lens portion of a front camera or a speaker portion. Alternatively, the electronic device  1  may include the light source  600  and the imaging element  8  without having a display. 
     The electronic device  1  according to the present embodiment may acquire information regarding fingerprints, or may acquire information regarding the spectrum unique to human skin by decomposing, by the imaging element, the wavelength of light that is diffused and propagated into the finger and that is returned to the electronic device side again. Alternatively, information regarding the vein may be acquired by light in a near-infrared region. Light emission is enabled according to the wavelength specification of the light source  600  specialized for authentication. 
     In the electronic device  1  illustrated in (b), the light source  600  is disposed such that light is incident in parallel with the cover glass  7 . Then, the imaging element  8  receives light reflected or scattered around the reading surface. With this configuration, the fingerprint can be read by the light transmitted through the finger. 
     In the electronic device  1  illustrated in (c), the light source  600  is disposed so as to generally totally reflect light with the cover glass  7  as a light guide plate. A part of the light from the light source  600  enters the subject and diffuses, and the light emitted from the reading surface is received by the imaging element  600 . These embodiments use scattered light in the finger, and thus, are resistant to sweat and drying. Therefore, the fingerprint recognition rate is improved even in an environment where sweat and drying occur. 
     In the electronic device  1  illustrated in (d), the light source  600  is disposed to face the reading surface across a subject such as a finger, and the imaging element  8  receives light that has passed through or scattered from the subject and passed through the reading surface. The light source  600  may be provided so as to be detachable from the electronic device  1 , for example. Alternatively, a system may be used in which a mobile terminal such as a smartphone provided with the imaging element  8  according to the present embodiment is brought close to the fixed light source  600  and then light is emitted. The operation commands between the light source  600  and the mobile terminal may be synchronized by wireless communication such as infrared rays. The light source  600  may include a mold processed into a shape in which a subject such as a finger is easily fixed, and may further include a jig capable of fixing the mobile terminal at a predetermined position. Alternatively, a subject such as a finger may be brought close to the light source  600  while being in direct contact with the mobile terminal, and when it is detected that, for example, the subject approaches a predetermined position, the light source  600  may emit light, and the imaging element may synchronously receive light by wireless communication. The detecting means may be a physical contact button, a detection sensor for a mobile terminal or a subject, or a signal from a mobile terminal. 
     As described above, in the electronic device  1  according to the present embodiment, the light source  600  different from the display unit  2  is disposed. As a result, it is possible to perform image capture at a position and a wavelength according to an imaging environment of a subject such as a finger, and the fingerprint recognition rate is further improved. 
     It is to be noted that the present technology may also have the following configurations. 
     (1) An electronic device including a plurality of pixels, 
     in which each of at least two pixels of the plurality of pixels includes: 
     a first lens that collects incident light; 
     a first light shielding film portion having a first hole through which a part of the incident light that has been collected passes; and 
     a photoelectric conversion unit configured to photoelectrically convert the incident light having passed through the first hole, and 
     a shape of the first hole with respect to the first light shielding film portion is different between a first pixel among the at least two pixels and a second pixel different from the first pixel among the at least two pixels. 
     (2) The electronic device according to (1), in which the first pixel further includes a second lens that collects the incident light having been collected by the first lens into the first hole. 
     (3) The electronic device according to (1) or (2), in which the first lens is a reflow lens. 
     (4) The electronic device according to (3), in which a reflow stopper is provided at a boundary between the two first lenses corresponding to two adjacent pixels. 
     (5) The electronic device according to (4), in which the reflow stopper contains a light shielding material. 
     (6) The electronic device according to any one of (1) to (5), further including a first optical system that collects incident light on the plurality of pixels, 
     in which the first lens collects the incident light having been collected through the first optical system, and 
     the first lens is disposed at a position corresponding to a direction of the incident light incident from a predetermined position through the first optical system. 
     (7) The electronic device according to any one of (1) to (6), in which at least one element in a second optical system including the first lens that collects the incident light into the first hole is a diffraction lens. 
     (8) The electronic device according to any one of (1) to (7), in which shapes of the first holes included in the first pixel and the second pixel are different corresponding to a shape of a light distribution of a second optical system including the first lens that collects the incident light into the first hole from a predetermined position. 
     (9) The electronic device according to any one of (1) to (8), in which the first pixel and the second pixel are different from each other in a position of the first hole with respect to the first light shielding film portion. 
     (10) The electronic device according to any one of (1) to (9), in which the first pixel and the second pixel are different from each other in an opening area of the first hole. 
     (11) The electronic device according to any one of (1) to (10), in which the first hole includes a plasmon filter that has a plurality of holes smaller than the opening. 
     (12) The electronic device according to any one of (1) to (11), further including a light shielding wall in a plurality of stages arranged between two adjacent pixels among the plurality of pixels. 
     (13) The electronic device according to (3) or (12), in which an uppermost portion of the light shielding wall is provided as the reflow stopper. 
     (14) The electronic device according to (12), in which the light shielding wall in a plurality of stages is arranged according to a direction of the incident light collected from a predetermined position through a second optical system including the first lens. 
     (15) The electronic device according to any one of (1) to (14), 
     in which the first pixel further includes 
     a second light shielding film portion including, on a light entrance side with respect to the first light shielding film portion, a second hole through which a part of the incident light having been collected passes, the second hole being larger than the first hole. 
     (16) The electronic device according to (11) and (15), 
     in which, in the first pixel, the second light shielding portion and a metal film of the light shielding wall include a same material and are continuously provided. 
     (17) The electronic device according to any one of (1) to (16), 
     in which the first pixel further includes 
     an antireflection portion having an uneven structure on a surface of the first light shielding film portion on a side of the photoelectric conversion element. 
     (18) The electronic device according to any one of (1) to (17), 
     in which the first pixel further includes 
     a photoelectric conversion element separation portion that does not propagate information regarding an intensity of acquired light to the photoelectric conversion unit adjacent to the first pixel. 
     (19) The electronic device according to any one of (1) to (18), 
     in which, in the pixels, the first pixel further includes 
     a reflection film portion on a bottom part on a side opposite to a light entrance side of the photoelectric conversion element unit. 
     (20) The electronic device according to any one of (1) to (19), in which at least two of the plurality of pixels are phase detection pixels which are paired. 
     (21) The electronic device according to any one of (1) to (20), further including an image processing unit that performs processing for restoring resolution of an image by image processing using a point spread function corresponding to the first hole. 
     (22) The electronic device according to any one of (1) to (21), 
     in which at least one of the plurality of pixels is a polarization pixel having a polarizing element, and 
     the electronic device corrects an image signal photoelectrically converted by at least one of the plurality of pixels on the basis of polarization information obtained by polarization by a plurality of the polarizing elements and photoelectric conversion by the photoelectric conversion unit. 
     (23) The electronic device according to any one of (1) to (22), 
     in which each of the plurality of pixels further includes a charge holding unit that is shielded from light, and 
     the electronic device enables transfer of a charge from the photoelectric conversion element to the charge holding unit, and sets exposure timings of the plurality of pixels to be the same. 
     (24) The electronic device according to any one of (1) to (23), 
     in which at least two pixels of the plurality of pixels output image signals on the basis of incident light incident via optical members having wavelengths with different transmission characteristics, and 
     the electronic device further includes an authentication unit determining that an object to be imaged is an artificial object in a case where there is no peak around 760 nanometers on the basis of the image signals output from the at least three pixels. 
     (25) The electronic device according to any one of (1) to (24), 
     in which at least two pixels of the plurality of pixels output image signals on the basis of incident light incident via optical members having wavelengths with different transmission characteristics, and 
     the electronic device determines that an object to be imaged is an artificial object in a case where there is no rise in a wavelength region from 500 to 600 nanometers on the basis of the image signals output from the at least three pixels. 
     (26) The electronic device according to any one of (1) to (21), 
     in which at least two pixels of the plurality of pixels output image signals on the basis of incident light incident via optical members having wavelengths with different transmission characteristics, and 
     the electronic device calculates an absorption coefficient spectrum of oxygenated hemoglobin and an absorption coefficient spectrum of reduced hemoglobin on the basis of the image signals output from the at least two pixels, and 
     determines that an object to be imaged is an artificial object in a case where a ratio of a difference value between the absorption coefficient spectrum of the oxygenated hemoglobin and the absorption coefficient spectrum of the reduced hemoglobin at predetermined two wavelengths is outside a predetermined range. 
     (27) The electronic device according to any one of (1) to (26), in which the first pixel and the second pixel are different from each other in a size of the first hole with respect to the first light shielding film portion, and a region of the photoelectric conversion element of the first pixel or the second pixel having the first hole with a larger size is set to be greater than a region of the photoelectric conversion element of the first pixel or the second pixel having the first hole with a smaller size. 
     (28) The electronic device according to any one of (1) to (27), 
     in which outputs of the plurality of pixels are addable, and 
     the first hole corresponding to a pixel on a peripheral part of a region where the plurality of pixels is arrayed is smaller in size than the first hole corresponding to a pixel at a central part of the region. 
     (29) The electronic device according to any one of (1) to (29), further including a display unit, 
     in which the incident light is incident on the photoelectric conversion unit via the display unit. 
     The modes of the present disclosure are not limited to the above-described individual embodiments, and include various modifications that could be conceived of by those skilled in the art. In addition, the effects of the present disclosure are not limited to the effects described above. That is, various additions, modifications, and partial deletions are possible without departing from the conceptual idea and spirit of the present disclosure derived from the matters defined in the claims and equivalents thereof. 
     REFERENCE SIGNS LIST 
     
         
           1  Electronic device 
           1   a  Display screen 
           2  Display unit 
           4  Display panel 
           5  Touch panel 
           6  Circularly polarizing plate 
           7  Cover glass 
           8  Imaging unit 
           8   a  Photoelectric conversion unit 
           9  Optical system 
           12  Semiconductor substrate 
           13  Interlayer insulating film 
           14  Flattened layer 
           15  Light shielding layer 
           16  Base insulating layer 
           17  Insulating layer 
           22  Pixel 
           22   x  Pixel 
           22   p  Pixel 
           50   a  to  k  Pinhole 
           50  First light shielding film portion 
           51  Photoelectric conversion unit 
           52  Second light shielding film portion 
           52 A Second light shielding film portion 
           54  Third light shielding film portion 
           61  Light shielding wall 
           61 A First light shielding wall 
           61 B Second light shielding wall 
           61 C Third light shielding wall 
           63  Antireflection portion (moth-eye) 
           72  On-chip lens 
           100  Polarization pixel 
           102  Charge holding unit 
           121  Inner lens 
           301  Phase pixel 
           302  Phase pixel 
           514  Authentication unit 
           518  Image processing unit 
           552  Transfer transistor 
           554  Charge holding unit 
         D 2  to D 8  Diffraction lens 
         PD, PD 1 , PD 2  Photoelectric conversion unit