Patent Publication Number: US-10319764-B2

Title: Image sensor and electronic device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase of International Patent Application No. PCT/JP2016/066570 filed on Jun. 3, 2016, which claims priority benefit of Japanese Patent Application No. JP2015-122530 filed in the Japan Patent Office on Jun. 18, 2015. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present technology relates to an image sensor and an electronic device, and particularly, to an image sensor and an electronic device capable of achieving high quality in a captured image. 
     BACKGROUND ART 
     There is an image sensor using an organic photoelectric conversion film as a photoelectric conversion element (for example, see Patent Literature 1). Since the organic photoelectric conversion film can simultaneously perform color separation and light reception as a thin film, an aperture ratio is high and an on-chip lens is basically unnecessary. 
     There is also an image sensor in which a photodiode is also formed in a silicon layer below an organic photoelectric conversion film and phase difference detection is performed by the photodiode of the silicon layer while an image is acquired by the organic photoelectric conversion film (for example, see Patent Literature 2). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent No. 5244287 
     Patent Literature 2: JP 2011-103335A 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     In the structure disclosed in Patent Literature 2, however, when a condensing point of an on-chip lens is set in the photodiode of the silicon layer, a radius of curvature of the on-chip lens decreases, and thus oblique incidence characteristics may deteriorate. Therefore, as an image height (a distance from an optical center) increases, an amount of received light decreases and sensitivity unevenness called shading occurs. 
     The present disclosure was finalized in view of this situation and is capable of achieving high quality in a captured image. 
     Solution to Problem 
     According to an aspect of the present technology, there is provided an image sensor in which photoelectric conversion layers including photoelectric conversion units separated in units of pixels are stacked in two or more layers, the image sensor is configured to include a state in which light incident on one pixel in a first photoelectric conversion layer closer to an optical lens is received by the photoelectric conversion unit in a second photoelectric conversion layer distant from the optical lens, the image sensor includes a light-shielding layer configured to shield light transmitted through the first photoelectric conversion layer, between the first photoelectric conversion layer and the second photoelectric conversion layer, the light-shielding layer has an opening to transmit the light from the first photoelectric conversion layer to the second photoelectric conversion layer, and the openings are made to be asymmetric with respect to the pixel in the first photoelectric conversion layer. 
     The openings may have different asymmetry in accordance with an image height of the optical lens. 
     Asymmetry of the openings may increase when an image height of the optical lens is raised. 
     Sides that form the opening may be disposed at positions shifted from sides that form a pixel in the first photoelectric conversion layer in which the opening is located. Among the sides that form the opening, a first side located on a central side of the optical lens and a second side different from the first side may be shifted by different shift amounts. 
     The shift may be performed in a horizontal direction. 
     The shift may be performed in a horizontal direction and a diagonal direction. 
     The shift may be performed in a vertical direction. 
     The shift may be performed in a vertical direction and a diagonal direction. 
     The shift may be performed in at least one of a horizontal direction, a vertical direction, and a diagonal direction. 
     A pixel of the photoelectric conversion unit in the second photoelectric conversion layer may be a phase difference detection pixel. 
     The image sensor may further include: a light-shielding unit configured to shield light transmitted through the opening, between the light-shielding layer and the second photoelectric conversion layer. The pixel of the photoelectric conversion unit in the second photoelectric conversion layer may be configured in a state in which the light is half shielded by the light-shielding unit. The pixel of the photoelectric conversion unit in the second photoelectric conversion layer may be set as a phase difference detection pixel. 
     The image sensor may further include a light-shielding unit formed between the first photoelectric conversion layer and the second photoelectric conversion layer in a grid state in which the light transmitted through the first photoelectric conversion layer is shielded. 
     Grids of the light-shielding units disposed to be adjacent to each other may be grids in different directions. 
     The image sensor may further include a narrow-band filter between the first photoelectric conversion layer and the second photoelectric conversion layer. The light transmitted through the first photoelectric conversion layer may arrive at the photoelectric conversion unit of the second photoelectric conversion layer via the filter. 
     The image sensor may further include: a plasmon filter between the first photoelectric conversion layer and the second photoelectric conversion layer. The light transmitted through the first photoelectric conversion layer arrives at the photoelectric conversion unit of the second photoelectric conversion layer via the plasmon filter. 
     The image sensor may further include a Fabry-Pérot interferometer between the first photoelectric conversion layer and the second photoelectric conversion layer. The light transmitted through the first photoelectric conversion layer arrives at the photoelectric conversion unit of the second photoelectric conversion layer via the Fabry-Pérot interferometer. 
     The photoelectric conversion unit in the second photoelectric conversion layer may form a time of flight (TOF) type sensor. 
     The photoelectric conversion unit in the second photoelectric conversion layer may form a light field camera. 
     The photoelectric conversion unit in the second photoelectric conversion layer may be used as a sensor that images a subject and acquires an image. 
     According to an aspect of the present technology, an electronic device includes an image sensor, in which photoelectric conversion layers including photoelectric conversion units separated in units of pixels are stacked in two or more layers, the image sensor is configured to include a state in which light incident on one pixel in a first photoelectric conversion layer closer to an optical lens is received by the photoelectric conversion unit in a second photoelectric conversion layer distant from the optical lens, the image sensor includes a light-shielding layer configured to shield light transmitted through the first photoelectric conversion layer, between the first photoelectric conversion layer and the second photoelectric conversion layer, the light-shielding layer has an opening to transmit the light from the first photoelectric conversion layer to the second photoelectric conversion layer, and the openings are made to be asymmetric with respect to the pixel in the first photoelectric conversion layer. 
     In an image sensor according to an aspect of the present technology, photoelectric conversion layers including photoelectric conversion units separated in units of pixels are stacked in two or more layers, the image sensor is configured to include a state in which light incident on one pixel in a first photoelectric conversion layer closer to an optical lens is received by the photoelectric conversion unit in a second photoelectric conversion layer distant from the optical lens, the image sensor includes a light-shielding layer configured to shield light transmitted through the first photoelectric conversion layer, between the first photoelectric conversion layer and the second photoelectric conversion layer, the light-shielding layer has an opening to transmit the light from the first photoelectric conversion layer to the second photoelectric conversion layer, and the openings are made to be asymmetric with respect to the pixel in the first photoelectric conversion layer. 
     According to an aspect of the present technology, an electronic device includes the image sensor. 
     Advantageous Effects of Invention 
     According to an aspect of the present technology, it is possible to achieve high quality in a captured image. 
     In addition, the advantageous effect described here is not necessarily limiting, and any advantageous effect described in the present disclosure may be included. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating an imaging mechanism including an image sensor according to the present disclosure. 
         FIG. 2  is an explanatory diagram illustrating a configuration of an image sensor to which the present technology is applied. 
         FIG. 3  is an explanatory diagram illustrating a configuration of an image sensor to which the present technology is applied. 
         FIG. 4  is a diagram illustrating a configuration of an image sensor according to the related art. 
         FIG. 5  is an explanatory diagram illustrating mixed color occurring depending on the size of an opening. 
         FIG. 6  is an explanatory diagram illustrating mixed color occurring depending on the size of an opening. 
         FIG. 7  is an explanatory diagram illustrating mixed color occurring depending on the size of an opening. 
         FIG. 8  is an explanatory diagram illustrating a configuration of the image sensor. 
         FIG. 9  is an explanatory diagram illustrating left-right asymmetry of the opening. 
         FIG. 10  is an explanatory diagram illustrating shift of the opening. 
         FIG. 11  is an explanatory diagram illustrating an image height and a shift amount. 
         FIG. 12  is an explanatory diagram illustrating an image height and a shift amount. 
         FIG. 13  is an explanatory diagram illustrating refraction of light in an on-chip lens. 
         FIG. 14  is an explanatory diagram illustrating shift of the opening. 
         FIG. 15  is an explanatory diagram illustrating shift of the opening. 
         FIG. 16  is an explanatory diagram illustrating shift of the opening. 
         FIG. 17  is an explanatory diagram illustrating shift of the opening. 
         FIG. 18  is an explanatory diagram illustrating a phase difference detection pixel. 
         FIG. 19  is an explanatory diagram illustrating disposition of the phase difference detection pixel. 
         FIG. 20  is an explanatory diagram illustrating disposition of the phase difference detection pixel. 
         FIG. 21  is an explanatory diagram illustrating a phase difference detection result. 
         FIG. 22  is an explanatory diagram illustrating a configuration of a light-shielding pixel. 
         FIG. 23  is an explanatory diagram illustrating a configuration of a light-shielding pixel. 
         FIG. 24  is an explanatory diagram illustrating detection intensity in the light-shielding pixel. 
         FIG. 25  is an explanatory diagram illustrating occurrence of mixed color. 
         FIG. 26  is an explanatory diagram illustrating a configuration of a grid light-shielding film. 
         FIG. 27  is an explanatory diagram illustrating a configuration of a grid light-shielding film. 
         FIG. 28  is an explanatory diagram illustrating another configuration of the grid light-shielding film. 
         FIG. 29  is an explanatory diagram illustrating another configuration of the grid light-shielding film. 
         FIG. 30  is a diagram illustrating a configuration of an image sensor in which a narrow-band filter is installed. 
         FIG. 31  is a diagram illustrating a configuration of an image sensor in which a plasmon filter is installed. 
         FIG. 32  is a diagram illustrating a configuration of the plasmon filter. 
         FIG. 33  is a diagram illustrating a configuration of an image sensor that includes a Fabry-Pérot interferometer. 
         FIG. 34  is a diagram illustrating a configuration of the Fabry-Pérot interferometer. 
         FIG. 35  is a diagram illustrating a configuration of an image sensor that includes a TOF type sensor. 
         FIG. 36  is an explanatory diagram illustrating an operation of the TOF type sensor. 
         FIG. 37  is a diagram illustrating a configuration of an image sensor that includes an LFC type sensor. 
         FIG. 38  is a diagram illustrating a configuration of an image sensor when imaging is performed with two layers. 
         FIG. 39  is an explanatory diagram illustrating another configuration of the image sensor. 
         FIG. 40  is an explanatory diagram illustrating another configuration of the image sensor. 
         FIG. 41  is an explanatory diagram illustrating another configuration of the image sensor. 
         FIG. 42  is an explanatory diagram illustrating a use example of the image sensor. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
     Hereinafter, modes for carrying out the present technology (hereinafter referred to as embodiments) will be described. In addition, the description will be made in the following order.
     1. Configuration of imaging device   2. Configuration of imaging mechanism   3. Mixed color in accordance with size of opening   4. Configuration of image sensor to which present technology is applied   5. Embodiment in which pixel in second layer is set as phase difference detection pixel   6. Configuration in which light-shielding film in grid state is included   7. Configuration in which narrow-band filter is included   8. Configuration in which plasmon filter is included   9. Configuration in which Fabry-Pérot interferometer is included   10. Configuration in which TOF type sensor is included   11. Configuration in which LFC type sensor is included   12. Configuration in which image is captured in two layers   13. Other configurations   14. Use example of image sensor
 
&lt;Configuration of Imaging Device&gt;
   

     The present technology to be described below can be applied to all electronic devices in which semiconductor packages are used in image acquisition units (photoelectric conversion units), for example, imaging devices such as digital still cameras or video cameras, portable terminal devices such as mobile phones with an imaging function, and copying machines in which imaging devices are used in image reading units. 
       FIG. 1  is a block diagram illustrating an example of a configuration of an electronic device according to the present technology, for example, an imaging device. As illustrated in  FIG. 1 , an imaging device  10  according to the present technology includes an optical system including a lens group  21 , an image sensor (imaging device)  22 , a digital signal processor (DSP) circuit  23 , a frame memory  24 , a display unit  25 , a recording unit  26 , a manipulation unit  27 , and a power unit  28 . The DSP circuit  23 , the frame memory  24 , the display unit  25 , the recording unit  26 , the manipulation unit  27 , and the power unit  28  are connected to each other via a bus line  29 . 
     The lens group  21  acquires incident light (image light) from a subject and forms an image on an imaging surface of the image sensor  22 . The image sensor  22  converts an amount of incident light formed as the image on the imaging surface by the lens group  21  into an electric signal in units of pixels and outputs the electric signal as a pixel signal. 
     The DSP circuit  23  processes the signal from the image sensor  22 . For example, as will be described in detail, the image sensor  22  has pixels for detecting focus, processes signals from the pixels, and performs a process of detecting the focus. Also, the image sensor  22  has pixels for constructing an image of a captured subject, processes signals from the pixels, and performs a process of loading the processed signals to the frame memory  24 . 
     The display unit  25  is configured as a panel display device such as a liquid crystal display device or an organic electro luminescence (EL) display device and displays a moving image or a still image captured by the image sensor  22 . The recording unit  26  records a moving image or a still image captured by the image sensor  22  on a recording medium such as a video tape or a digital versatile disk (DVD). 
     The manipulation unit  27  issues manipulation instructions in regard to various functions of the imaging device through an operation by a user. The power unit  28  appropriately supplies various kinds of power serving as operation power of the DSP circuit  23 , the frame memory  24 , the display unit  25 , the recording unit  26 , and the manipulation unit  27  to supply targets. 
     &lt;Configuration of Imaging Mechanism&gt; 
       FIG. 2  is a diagram illustrating an imaging mechanism including the image sensor according to the present disclosure. 
     An image sensor  101  according to the present disclosure receives light of a subject  3  condensed by an optical lens  102 , as illustrated in  FIG. 2 . The image sensor  101  is equivalent to the image sensor  22  in  FIG. 1 . The optical lens  102  is equivalent to the optical lens group  21  of the imaging device  10  in  FIG. 1 . 
     The image sensor  101  is, for example, a compound image sensor in which two semiconductor substrates  111 A and  111 B are stacked. In each of the semiconductor substrates  111 A and  111 B, a photoelectric conversion unit and a photoelectric conversion layer including a charge detection unit that thus detects photoelectrically converted charges are formed. Semiconductors of the semiconductor substrates  111 A and  111 B are, for example, silicon (Si). An aperture  112  is formed between the two semiconductor substrates  111 A and  111 B. 
     In addition, hereinafter, of the two semiconductor substrates  111 A and  111 B, the semiconductor substrate  111 A closer to the optical lens  102  is referred to as an upper substrate  111 A and the semiconductor substrate  111 B further from the optical lens  102  is referred to as a lower substrate  111 B. Also, in a case in which the two semiconductor substrates  111 A and  111 B are not particularly distinguished from each other, the two semiconductor substrates  111 A and  111 B are also referred to as the substrates  111 . 
       FIG. 3  is a diagram illustrating a schematic configuration of the image sensor  101 . 
     In the upper substrate  111 A, a plurality of pixels  121 A are arranged in a 2-dimensional array form. An on-chip lens  131  is formed in each pixel  121 A. Pixel signals acquired by the plurality of pixels  121 A arranged in the upper substrate  111 A are used as image generation signals. Accordingly, the upper substrate  11 A functions as a pixel sensor. 
     In the lower substrate  111 B, a plurality of pixels  121 B are also arranged in a 2-dimensional array form. Pixel signals acquired by the plurality of pixels  121 B arranged in the lower substrate  111 B can be used as, for example, phase difference detection signals, as will be described. In this case, the lower substrate  111 B functions as a phase difference detection sensor. 
     In the aperture  112 , as illustrated in  FIG. 3 , openings  123  are formed at a predetermined interval. Thus, as the pixels  121 A of the upper substrate  111 A, there are pixels which transmit incident light through the lower substrate  111 B and pixels which do not transmit incident light through the lower substrate  111 B. 
     For example, as illustrated in  FIG. 2 , incident light passing through one pixel (hereinafter referred to as a transmission pixel) of the upper substrate  111 A corresponding to the opening  121  of the aperture  112  is incident on four pixels of 2×2 of the lower substrate  111 B. 
     In addition,  FIGS. 2 and 3  are explanatory diagrams illustrating a relation between the transmission pixels of the upper substrate  111 A and light-receiving pixels of the lower substrate  111 B receiving incident light from the transmission pixels of the upper substrate  111 A. Scales of pixel sizes of the upper substrate  111 A and the lower substrate  11 B are different. 
     In this way, in the image sensor  101  to which the present technology is applied, the pixels can be disposed in two layers and can be used as the pixels that have separate functions, for example, in such a manner that the pixels disposed in the upper layer are set as pixels performing normal imaging and the pixels disposed in the lower layer are set as phase difference detection pixels. 
     In an image surface phase difference sensor in which phase difference pixels are arranged in a part of an image sensor with a single-layered structure rather than a stacked structure, a condensing point of the on-chip lens is ideally a photodiode surface of a silicon layer, but is actually a deep position of the silicon layer. Therefore, an imaging condensing point is different from a phase difference detection condensing point and there is a problem that optimization of microlenses is incompatible. 
     Also, when a condensing point of an on-chip lens is set on the surface of a photodiode of the silicon layer, a radius of curvature of the on-chip lens decreases, and thus oblique incidence characteristics may deteriorate. Therefore, as an image height (a distance from an optical center) increases, an amount of received light decreases and shading occurs. 
     Accordingly, in the image sensor  101 , by stacking the two substrates  111  and disposing the phase difference detection pixels in the lower substrate  111 B, as will be described below, it is possible to increase the radius of curvature of the on-chip lens, and thus it is possible to suppress occurrence of shading. 
     Also, as will be described, incident light passing through one pixel of the upper substrate  111 A can also be received by a plurality of pixels greater than 2×2. Therefore, multi-viewpoint separation is performed, separation performance of the phase difference pixels is improved, and thus high performance of phase difference autofocus is possible. 
       FIG. 4  is a sectional view illustrating the image sensor  101 . The upper substrate  111 A is located above the image sensor  101 , and the on-chip lenses  131 , on-chip color filters  132 , and photodiodes  133  are disposed. The on-chip lens  131 , the on-chip color filter  132 , and the photodiode  133  form the pixel  121 A (see  FIG. 2 ). 
     Here, the photodiode  133  disposed in the upper substrate  111 A has been described, but a photoelectric conversion layer in which the photodiode  133  is disposed may be configured as an organic photoelectric conversion film or the like. Also, in a case in which the photoelectric conversion layer is configured as the organic photoelectric conversion film, a plurality of photoelectric conversion layers may be configured. Also, the upper substrate  111 A formed as a backside irradiation substrate has been described as an example, but the present technology can be applied to either a backside irradiation substrate or a frontside irradiation substrate. 
     A multilayer wiring layer  201  that includes a plurality of wiring layers and inter-layer insulation films is formed below the photodiodes  133  of the upper substrate  111 A. The multilayer wiring layer  201  can also be configured such that a plurality of transistor circuits included in a reading circuit that reads signal charges accumulated in the photodiodes  133  are formed near the upper substrate  111 A. 
     The aperture  112  is disposed below the upper substrate  111 A. 
     The lower substrate  111 B is configured by, for example, a silicon layer which is an n type (first conductive type) semiconductor region and a photodiode serving as a photoelectric conversion unit can be configured for each pixel by pn junction in the silicon layer. The size of the pixel in the lower substrate  111 B may be different from the size of the pixel in the upper substrate  111 A. 
     A multilayer wiring layer including a plurality of transistor circuits included in a reading circuit that reads signal charges accumulated in the photodiodes, a plurality of wiring layers, and inter-layer insulation films may be formed above or below the lower substrate  111 B. In an embodiment illustrated in  FIG. 4 , the upper substrate  111 A and the lower substrate  111 B are joined (adhered) via an inter-layer insulation film  202 . 
     Pixels  152 - 1  to  152 - 5  are disposed in the lower substrate  111 B. The pixels  152  are equivalent to the pixels  121 B in  FIG. 2 . Here, the pixels  152 - 1  to  152 - 5  are assumed to be photodiodes and are also appropriately described as the photodiodes  152 . 
     Also, the pixels  152 - 1  to  152 - 5  are appropriately described as a pixel group  151 . The pixel group  151  is not limited to a case in which five pixels are included, but a plurality of pixels may be included. 
     The pixels  152 - 11  to  152 - 5  receive light transmitted through one on-chip lens  131 . 
     The wiring layers of the multilayer wiring layer  201  include wirings formed of copper or the like. The multilayer wiring layer  201  can also be configured to also function as a light-shielding film along with the aperture  112 . As illustrated in  FIG. 4 , in a case in which the on-chip lens  131  illustrated in the middle of the drawing is assumed to be an on-chip lens  131 A, light transmitted through the on-chip lens  131 A is configured to be received by one of the pixels  152 - 1  to  152 - 5  via an opening  123  of the aperture  112 . 
     On the other hand, light from the on-chip lens  131  different from the on-chip lens  131 A, for example, the on-chip lens  131 B near to the right of the on-chip lens  131 A, is configured not to be received by the pixels  152 - 1  to  152 - 5  without being transmitted through the aperture  112 . 
     In this way, light shielding of the aperture  112  is configured so that light transmitted through one on-chip lens  131  can be received by the pixel group  151  of the lower substrate  111 B. 
     &lt;Mixed Color in Accordance with Size of Opening&gt; 
     For example, the opening  123  of the aperture  112  can be configured to have the same size as the size of one pixel which is the size of the pixel  121 A of the upper substrate  111 A, as illustrated in  FIG. 3 . In other words, the opening can be formed with the same size as the transmission pixel and at a position immediately below the transmission pixel.  FIG. 4  illustrates a configuration in which the opening has the same size as the pixel  121 A. In this way, in a case in which the opening  123  has the same size as the pixel  121 A and is located at the same position, reflection or diffraction occurs and there is a possibility of condensing efficiency deteriorating. 
     This problem will be described with reference to  FIG. 5 .  FIG. 5  is a graph illustrating a relation between an angle of incidence of light in the image sensor  101  that has the configuration illustrated in  FIG. 4  and an amount of light received in the pixel  152 . In the graph illustrated in  FIG. 5 , the horizontal axis represents an angle of incidence of a ray and the vertical axis represents sensitivity characteristics (Pabs total). Numerals in the drawing are numerals indicating the pixels  152 - 1  to  152 - 5  (see  FIG. 4 ). For example, “1” indicates the pixel  152 - 1 . 
     In the graph illustrating phase difference characteristics illustrated in  FIG. 5 , it can be read that a pixel obtaining a peak value is different in accordance with an angle of incidence of a ray. For example, in a case in which the angle of incidence of the ray is 0 degrees, the pixel  152 - 5  has a highest peak value. In a case in which the angel of incidence of the ray is −15 degrees, the pixel  152 - 4  has a highest peak value. 
     Also, from  FIG. 5 , it can be read that the amount of light received by the pixels  152 - 1  to  152 - 5  is small. In particular, it can be read that light with a high angle of incidence, for example, an angle of incidence equal to or less than −30 degrees in  FIG. 5 , is rarely received. The pixels  152 - 1  and  152 - 2  are in a state in which a graph with peaks is not obtainable. 
     In a case in which the aperture  112  is configured to have the same size as the pixel  121 A and to be located at the same position, mixed color from adjacent pixels is reduced, but necessary light becomes vignetting. Thus, the amount of received light may be reduced. 
     Accordingly, a case in which the opening  123  of the aperture  112  is wide will be considered.  FIG. 6  is a graph illustrating a relation between the amount of light received by the pixels  152  and an angle of incidence of light in the image sensor  101  that has the configuration illustrated in  FIG. 4  in a case in which the opening  123  of the aperture  112  is wide (not illustrated). 
     As in the graph illustrated in  FIG. 5 , in the graph illustrated in  FIG. 6 , the horizontal axis represents an angle of incidence of a ray and the vertical axis represents sensitivity characteristics. Numerals in the drawing are numerals indicating the pixels  152 - 1  to  152 - 5  (see  FIG. 4 ). 
     When the graph illustrated in  FIG. 5  is compared to the graph illustrated in  FIG. 6 , it can be read that sensitivity is raised on the whole in the graph illustrated in  FIG. 6 . Also, for example, referring to the graph (the graph illustrating sensitivity of the pixel  152 - 3 ) that has a peak in a range of the angle of incidence from −25 to −20 degrees, it can be read that a level is raised at a high angle of incidence and light at the high angle of incidence is also received. 
     In the configuration in which the opening  123  of the aperture  112  is wide, it is possible that necessary light does not become vignetting. However, mixed color from adjacent pixels may be larger. 
     Ideally, the opening  123  in which a graph illustrated in  FIG. 7  is obtained is preferable. As in the graph illustrated in  FIGS. 5 and 6 , in the graph illustrated in  FIG. 7 , the horizontal axis represents an angle of incidence of a ray and the vertical axis represents sensitivity characteristics. Numerals in the drawing are numerals indicating the pixels  152 - 1  to  152 - 5  (see  FIG. 4 ). 
     Referring to the graph illustrated in  FIG. 7 , a peak can be obtained in any of the pixels  152 - 1  to  152 - 5 . From this point, it can be read that since any of the pixels  152  includes a high angle of incidence and light can be received with high sensitivity, the light reception of the high sensitivity can be realized even in the pixel group  151 . 
     Also, referring to the graph (the graph illustrating the sensitivity of the pixel  152 - 3 ) that has a peak in a range of an angle of incidence from −25 to −20 degrees, it can be read that a level is lowered in a range out of the range of the angle of incidence from −25 to −20 degrees and an influence of the mixed color from the adjacent pixels is suppressed. 
     The image sensor  101  in which such a graph is obtained will be described below. 
     &lt;Configuration of Image Sensor to which Present Technology is Applied&gt; 
       FIG. 8  is a diagram illustrating an embodiment of the configuration of the image sensor  101  to which the present technology is applied. The image sensor  101  illustrated in  FIG. 8  and the image sensor  101  illustrated in  FIG. 4  basically have the same configuration, but the position, the size, the shape, or the like of the opening  123  of the aperture  112  differs. Here, to indicate a difference from the aperture  112  of the image sensor  101  illustrated in  FIG. 4 , an aperture  301  is described and the opening  123  is also described as an opening  302 . 
     The opening  302  of the aperture  301  illustrated in  FIG. 8  is formed at a position spanning two pixels. That is, this configuration is different from the above-described configuration in which the opening  302  is installed immediately below the transmission pixel. The aperture  301  is formed of a material such as metal through which light is not transmitted and functions as a light-shielding layer that shields light transmitted through the upper substrate  111 A. Accordingly, of the light transmitted through the upper substrate  111 A, light other than the light transmitted through the opening  302  is shielded by the aperture  112  and does not arrive at the lower substrate  111 B. 
     In addition, a portion of the opening  302  of the aperture  301  is also opened in the multilayer wiring layer  201 . Accordingly, the following description is also applied to an opening of the multilayer wiring layer  201 . Also, the description will continue assuming the aperture  301  and the multilayer wiring layer  201  are separated and the aperture  301  is exemplified. A configuration in which the multilayer wiring layer  201  has the function (the light-shielding function) of the aperture  301  and the aperture  301  is omitted can also be realized. Alternatively, the aperture  301  can also be formed of a material with conductivity and function as the multilayer wiring layer  201 . 
     That is, a light-shielding layer installed between the upper substrate  111 A and the lower substrate  111 B may be configured as the aperture  301 , may be configured as the aperture  301  and the multiplayer wiring layer  201 , or may be configured as the multiplayer wiring layer  201 . 
     The opening  302  is installed from the vicinity of the middle of the on-chip lens  131 A to the vicinity of the middle of the adjacent on-chip  131 C. In this way, the opening  302  is not installed below one pixel (the photodiode  133 ) installed in the upper substrate  111 A, but is installed across a plurality of pixels. 
     The size of the opening  302  will be further described with reference to  FIG. 9 . The on-chip lens  131 A and the on-chip lens  131 C are illustrated and each central axis is illustrated with a dotted line. The diameter of one on-chip lens  131 , in other words, the width size of one pixel, is assumed to be a size a. 
     As illustrated in  FIG. 9 , the opening  302  of the aperture  301  starts from a location moved by a size b to the right from the central axis of the on-chip lens  131 A. Also, the opening  302  ends at a location moved by a size d to the left from end of the on-chip lens  131 A. The opening  302  includes the size b. The size b is equivalent to a half of the size a (the radius of the on-chip lens  131 A). 
     In this case, the size of the opening  302  is a size (b+c+d). The size (b+c+d) may be the same as the size a or may be less or greater than the size a. 
     When the on-chip lens  131 A is focused, in other words, when the transmission pixel in which the opening  302  is installed is focused, the opening  302  is not installed with the same size centering on the central axis, but is installed to be left-right asymmetric. In the example illustrated in  FIG. 9 , a size of the opening  302  installed to the right of the central axis of the on-chip lens  131 A is the size b and a size of the opening  302  installed to the left of the central axis of the on-chip lens  131 A is a size (c+d). The size b is not the same as, but is different from the size (c+d). 
     In this way, when the opening  302  is viewed from the on-chip lens  131 A (the transmission pixel), the left and right sizes are different and the opening  302  is installed to be left-right asymmetric. 
     Referring back to  FIG. 4 , the opening  123  of the aperture  112  illustrated in  FIG. 4  is installed immediately below the on-chip lens  131 A, has the same sizes centering on the central axis, and is installed to be left-right symmetric. In this way, when the opening  123  is installed to be left-right symmetric centering on the central axis of the on-chip lens  131 A, there is a possibility of vignetting or mixed color occurring, as described with reference to  FIGS. 5 and 6 . 
     However, as described with reference to  FIGS. 8 and 9 , by installing an opening that has different sizes centering on the central axis of the on-chip lens  131 A and is left-right asymmetric as in the opening  302  of the aperture  301 , it is possible to prevent mixed color from adjacent pixels without generating vignetting of necessary light. Thus, it is possible to realize the image sensor  101  in which the graph illustrated in  FIG. 7  can be obtained. 
     When the opening  302  is viewed from the upper side of the image sensor  101 , the opening  302  is installed to have a shape and a size at a position, as illustrated in  FIG. 10 .  FIG. 10  is a diagram illustrating a screen image and a pixel (the photodiode  133  in  FIG. 10 ) disposed in the upper substrate  111 A in a first layer of the screen image in which the opening  302  is installed. 
     A screen image  401  illustrated in  FIG. 10  indicates a part of an image captured by the imaging apparatus  10  (see  FIG. 1 ). Five openings  302 - 1  to  302 - 5  are disposed in the screen image in the screen image  401 . Photodiodes  133 - 1  to  133 - 5  in which the openings  302 - 1  to  302 - 5  are disposed are illustrated. In  FIG. 10 , the opening  302  is indicated with a quadrangular frame and the photodiode  133  (pixel) is indicated with a quadrangle (square) with oblique lines. 
     In addition, in  FIG. 10  in the following description, five pixels will be described as an example. The openings  302  can be installed from several pixels to all the pixels, the number of openings and disposition positions of the openings can be changed in accordance with uses or precision, and shift amounts to be described below can also be changed. 
     The opening  302 - 3  disposed at the position of the photodiode  133 - 3  disposed in the middle of the screen image  401  is opened with a size which is substantially left-right target. The opening  302 - 2  disposed at the position of the photodiode  133 - 2  disposed in the neighborhood to the left of the photodiode  133 - 3  is opened with a size which is left-right asymmetric and is opened at a position shifted to the left of the photodiode  133 - 3 . 
     The opening  302 - 1  disposed at the position of the photodiode  133 - 1  disposed in the neighborhood to the left of the photodiode  133 - 2  is opened with a size which is left-right asymmetric and is opened at a position shifted to the left of the photodiode  133 - 1 . Also, a shift amount in the opening  302 - 1  is larger than in the opening  302 - 2 . 
     Similarly, the opening  302 - 4  disposed at the position of the photodiode  133 - 4  disposed in the neighborhood to the right of the photodiode  133 - 3  is opened with a size which is left-right asymmetric and is opened at a position shifted to the right of the photodiode  133 - 4 . 
     The opening  302 - 5  disposed at the position of the photodiode  133 - 5  disposed in the neighborhood to the right of the photodiode  133 - 4  is opened with a size which is left-right asymmetric and is opened at a position shifted to the right of the photodiode  133 - 5 . Also, a shift amount in the opening  302 - 5  is larger than in the opening  302 - 4 . 
     In this way, the position of the opening  302  with respect to the photodiode  133  differs in accordance with the position of the opening  302 . In the example illustrated in  FIG. 10 , the opening is configured so that a shift amount from the central axis of the photodiode  133  is larger as the opening is oriented from the middle of the screen image  401  to the ends of the screen image  401 . In other words, the positions of the openings  302  are set in accordance with an image height of the optical lens  102  (see  FIG. 2 ). 
     That is, in the example illustrated in  FIG. 10 , a shift amount is larger as the image height is raised from the vicinity of proportion  0  (an end of the screen image  401 ) of the image height (the middle of the screen image  401 ). In other words, as the image height is raised, the asymmetry of the openings  302  increases. 
     Also, as the image height is raised, an opening area of the opening  302  may increase. In a case in which the opening area is enlarged in accordance with the image height, for example, the opening area (shift amount) can be set on the basis of a graph illustrated in  FIG. 11 or 12 . In the graphs illustrated in  FIGS. 11 and 12 , the horizontal axis represents an image height and the vertical axis represents a diaphragm shift amount. In the graphs, thick lines represent a shift amount of a central side and thin lines represent a shift amount of a peripheral side. 
     The central side means a side on which the image height is oriented to proportion  0  (the center of the image height). For example, sides on the central side of the opening  302  are a side located to the right of the opening  302 - 2  and a side located to the left of the opening  302 - 4  in  FIG. 10 . 
     The peripheral side is an opposite side to the central side and means a side on which the image height is oriented to the side of proportion  10 . For example, sides of the peripheral side of the opening  302  are a side located to the left of the opening  302 - 2  and a side located to the right of the opening  302 - 4  in  FIG. 10 . 
     Referring to  FIG. 11 , a shift amount of the image height of proportion  0  is 0 in both the central side and the peripheral side. A pixel of the image height of 0 proportion  0  is the photodiode  133 - 3  (see  FIG. 10 ) and a shift amount of the opening  302 - 3  at the location of the photodiode  133  is considered to be 0. Accordingly, as illustrated in  FIG. 10 , the photodiode  133 - 3  and the opening  302 - 3  are installed in a nearly overlapped state and are not left-right symmetric. 
     Also, a shift amount of the image height of proportion  9  is about 3 (a.u.) on the central side and is about 6 (a.u.) on the peripheral side. In a case in which a pixel of the image height of proportion  9  is the photodiode  133 - 5  (see  FIG. 10 ), a shift amount of the side of the central side of the opening  302 - 3  at the location of the photodiode  133 - 5  is considered to be about 3 and a shift amount of the peripheral side is considered to be about 6. 
     A shift amount of the central side is an amount by which the side of the central side is shifted to the left or right of the photodiode  133  and is set in accordance with the image height. In this case, the side (left side) of the central side of the opening  302 - 5  is installed at a position shifted to the right by about 3 (a.u.) from the left side of the photodiode  133 - 5 . 
     Similarly, a shift amount of the peripheral side is an amount by which the side of the peripheral side is shifted to the left or the right of the photodiode  133  and is set in accordance with the image height. In this case, the side (left side) of the peripheral side of the opening  302 - 5  is installed at a position shifted to the right by about 6 (a.u.) from the right side of the photodiode  133 - 5 . 
     The opening  302  installed in regard to the photodiode  133  located to the left of the photodiode  133  located in the middle is shifted by a shift amount in accordance with the image height to the left of the left side (the peripheral side) or the right side (the central side) of the photodiode  133 . 
     The shift amounts on the central side and the peripheral side differ. Therefore, the opening area of the opening  302  increases as the image height is raised. 
     A case in which the shift amount illustrated in  FIG. 11  increases at the same ratio in proportion to the image height is illustrated. As illustrated in  FIG. 12 , however, a shift amount may not increase at the same ratio in accordance with the image height. Referring to  FIG. 12 , a slope from the image height of proportion  0  to the image height of proportion  5  is not the same as a slope from the image height of proportion  5  to the image height of proportion  10 . 
     In this way, the shift amount may be set on the basis of a graph in which a slope is not simply proportional in accordance with the image height but is changed at a predetermined image height. The reason why the shift amount is set in this way will be described with reference to  FIG. 13 . 
     Although not illustrated in  FIG. 13 , when the image height of the optical lens  102  (see  FIG. 2 ) is changed, an angle of incidence light incident on the on-chip lens  131  is also changed. The left drawing of  FIG. 13  illustrates a case in which an angle of incidence of the incident light incident on the optical lens  102  is small. The right drawing of  FIG. 13  illustrates a case in which the angle of incidence is large. 
     Also, as illustrated in  FIG. 13 , the on-chip lens  131  has a spherical shape. From this, an angle of the incident light incident on the optical lens  102  is not proportional to an angle of light after refracted in the on-chip lens  131  in some cases. Accordingly, as illustrated in  FIG. 12 , by setting a shift amount on the basis of the graph in which the slope is different at a predetermined image height, it is possible to obtain the advantage of transmitting light necessary in the aperture  301  and the advantageous effect of cutting unnecessary light at the maximum. 
     In addition, the case in which two slopes are set is illustrated in  FIG. 12 , but the number of set slopes may be two or more. Also, in a case in which the advantageous effect at the time of setting of the shift amount using the graph in which the plurality of slopes illustrated in FIG  12  are set can be neglected or may not be necessarily considered, the shift amount may be set applying the graph in which one slope illustrated in  FIG. 11  is set. 
     The example of the opening  302  illustrated in  FIG. 10  is an example of the opening  302  disposed in the horizontal direction (lateral direction) of the screen image  401 . Although not illustrated in  FIG. 10 , openings are also installed on the upper side or the lower side (the vertical direction) of the openings  302 - 1  to  302 - 5  and are disposed at the same position in the horizontal direction. The openings  302  are shifted by the same shift amount and have the same opening area. 
     In this way, the openings  302  may be configured by setting the shift amounts only in the horizontal direction. However, as illustrated in  FIG. 14 , the openings  302  may be configured by setting shift amount in the horizontal direction and a diagonal direction. 
     The shift amounts can be set on the basis of the graph illustrated in  FIG. 11  or the graph illustrated in  FIG. 12 . In this case, in a pixel located on the upward left side of the middle, for example, a photodiode  133 - 2 - 1 , a side of the central side is considered to be the right side of an opening  302 - 2 - 1  and sides of the peripheral side is considered to the left side and the upper side of the opening  302 - 2 - 1 . Also, a lower side of the opening  302 - 2 - 1  is a side in the vertical direction. Therefore, in this case, the lower side is not a shift target side. 
     Also, in a pixel located on the upward right side of the middle, for example, a photodiode  133 - 4 - 1 , a side of the central side is considered to be the left side of an opening  302 - 4 - 1  and sides of the peripheral side are considered to be the right side and the upper side of the opening  302 - 4 - 1 . Also, the lower side of the opening  302 - 4 - 1  is a side in the vertical direction. Therefore, in this case, the lower side is not a shift target side. 
     Also, in a pixel located on the downward left side of the middle, for example, a photodiode  133 - 2 - 2 , a side of the central side is considered to be the right side of an opening  302 - 2 - 2  and sides of the peripheral side are considered to be the left side and the lower side of the opening  302 - 2 - 2 . Also, the upper side of the opening  302 - 2 - 2  is a side in the vertical direction. Therefore, in this case, the upper side is not a shift target side. 
     Also, in a pixel located on the downward right side of the middle, for example, a photodiode  133 - 4 - 2 , a side of the central side is considered to be the left side of an opening  302 - 4 - 2  and sides of the peripheral side are considered to be the right side and the lower side of the opening  302 - 4 - 2 . Also, the upper side of the opening  302 - 4 - 2  is a side in the vertical direction. Therefore, in this case, the upper side is not a shift target side. 
     In this way, the sides in the vertical direction are not shifted and the sides in the horizontal direction and the sides in the diagonal direction are shifted. 
     As illustrated in  FIG. 15 , the sides may be shifted only in the vertical direction.  FIG. 15  is a diagram illustrating an example of a case in which the shift amounts of the openings  302  of the aperture  301  are applied only in the vertical direction. The photodiodes  133  (the pixels) of the upper substrate  111 A in the first layer are shifted only in the vertical direction and are not shifted in the horizontal direction. 
     An opening  302 - 3 - 1  disposed at the location of the photodiode  133 - 3 - 1  disposed on the upward side of the pixel (the photodiode  133 - 3 ) located in the middle is shifted in the upward direction. Also, an opening  302 - 3 - 2  disposed at the location of the photodiode  133 - 3 - 2  disposed on the downward side of the photodiode  133 - 3  is shifted in the downward direction. 
     Although the other pixels are not illustrated, the openings  302  disposed on the upward side of the middle are shifted in the upward direction and the openings  302  disposed to the downward side of the middle are shifted in the downward direction, as in the openings  302 - 3 - 1  and  302 - 3 - 2 . 
     The shift amounts in a case in which the openings  302  are shifted in the vertical direction can also be set on the basis of the graph illustrated in  FIG. 11 or 12 . In this case, in the pixel located on the upward side of the middle, for example, the photodiode  133 - 3 - 1 , a side of the central side is considered to be the lower side of the opening  302 - 3 - 1  and a side of the peripheral side is considered to be the upper side of the opening  302 - 3 - 1 . 
     Also, in the pixel located on the downward side of the middle, for example, in the photodiode  133 - 3 - 2 , a side of the central side is considered to be the upper side of the opening  302 - 3 - 2  and a side of the peripheral side is considered to be the lower side of the opening  302 - 3 - 2 . 
     In this way, the openings may be shifted only in the vertical method. 
     Further, as illustrated in  FIG. 16 , the openings may be shifted in the vertical direction and the diagonal direction. The openings  302  of the aperture  301  are shifted in the vertical direction and the diagonal direction from the predetermined pixels (the photodiodes  133 ) of the upper substrate  111   a  in the first layer. 
     The shift amounts can be set on the basis of the graph illustrated in  FIG. 11  or the graph illustrated in  FIG. 12 . In this case, in a pixel located on the upward left side of the middle, for example, a photodiode  133 - 2 - 1 , a side of the central side is considered to be the lower side of an opening  302 - 2 - 1  and sides of the peripheral side is considered to the left side and the upper side of the opening  302 - 2 - 1 . Also, a right side of the opening  302 - 2 - 1  is a side in the horizontal direction. Therefore, in this case, the lower side is not a shift target side. 
     Also, in a pixel located on the upward right side of the middle, for example, a photodiode  133 - 4 - 1 , a side of the central side is considered to be the lower side of an opening  302 - 4 - 1  and sides of the peripheral side are considered to be the right side and the upper side of the opening  302 - 4 - 1 . Also, the left side of the opening  302 - 4 - 1  is a side in the horizontal direction. Therefore, in this case, the lower side is not a shift target side. 
     Also, in a pixel located on the downward left side of the middle, for example, a photodiode  133 - 2 - 2 , a side of the central side is considered to be the upper side of an opening  302 - 2 - 2  and sides of the peripheral side are considered to be the left side and the lower side of the opening  302 - 2 - 2 . Also, the right side of the opening  302 - 2 - 2  is a side in the horizontal direction. Therefore, in this case, the upper side is not a shift target side. 
     Also, in a pixel located on the downward right side of the middle, for example, a photodiode  133 - 4 - 2 , a side of the central side is considered to be the upper side of an opening  302 - 4 - 2  and sides of the peripheral side are considered to be the right side and the lower side of the opening  302 - 4 - 2 . Also, the left side of the opening  302 - 4 - 2  is a side in the horizontal direction. Therefore, in this case, the upper side is not a shift target side. 
     In this way, the sides in the horizontal direction are not shifted and the sides in the vertical direction and the sides in the diagonal direction are shifted. 
     Further, as illustrated in  FIG. 17 , the openings may be shifted in the horizontal direction, the vertical direction, and the diagonal direction. The openings  302  of the aperture  301  are shifted in the horizontal direction, the vertical direction, and the diagonal direction from the predetermined pixels (the photodiodes  133 ) of the upper substrate  111   a  in the first layer. 
     The shift amounts can be set on the basis of the graph illustrated in  FIG. 11  or the graph illustrated in  FIG. 12 . In this case, in a pixel located on the upward left side of the middle, for example, a photodiode  133 - 2 - 1 , a side of the central side is considered to be the lower side and the right side of an opening  302 - 2 - 1  and sides of the peripheral side is considered to the upper side and the left side of the opening  302 - 2 - 1 . 
     Also, in a pixel located on the upward right side of the middle, for example, a photodiode  133 - 4 - 1 , a side of the central side is considered to be the lower side and the left side of an opening  302 - 4 - 1  and sides of the peripheral side are considered to be the upper side and the right side of the opening  302 - 4 - 1 . 
     Also, in a pixel located on the downward left side of the middle, for example, a photodiode  133 - 2 - 2 , a side of the central side is considered to be the upper side and the right side of an opening  302 - 2 - 2  and sides of the peripheral side are considered to be the lower side and the left side of the opening  302 - 2 - 2 . 
     Also, in a pixel located on the downward right side of the middle, for example, a photodiode  133 - 4 - 2 , a side of the central side is considered to be the upper side and the left side of an opening  302 - 4 - 2  and sides of the peripheral side are considered to be the lower side and the right side of the opening  302 - 4 - 2 . 
     In this way, the sides related in the horizontal direction, the vertical direction, and the diagonal direction are shifted. In addition, here, the shift amounts are set separately on the central side and the peripheral side. Therefore, even when the sides related in the horizontal direction, the vertical direction, and the diagonal direction are shifted, four sides of the openings  302  can be each shifted by performing the process of shifting the sides related in the horizontal direction and the vertical direction. Accordingly, the process of shifting the sides related in the horizontal direction and the vertical direction may be performed. 
     Also, in the foregoing examples, the sides of the openings  302  are separated on the central side or the peripheral side and the sides of the corresponding openings  302  are shifted, as described above. However, the shift amounts of the corresponding sides in, for example, a diagonal direction may be set in addition to the central side and the peripheral side. 
     &lt;Embodiment in which Pixels in Second Layer are Set to Phase Difference Detection Pixels&gt; 
     As described above, in a case in which the openings  302  of the aperture  301  are disposed by changing the positions or sizes in accordance with the image height, the pixels disposed in the lower substrate  111 B in the second layer may be set to phase difference detection pixels. 
     Here, general phase difference detection pixels will be further described in brief.  FIG. 18  is a diagram illustrating a configuration of the phase difference detection pixel with a single-layered structure. In the phase difference detection pixel, a light-shielding film  452  that shields light from an on-chip lens  451  is configured to be installed between the on-chip lens  451  and a photodiode  453 . A part of light incident via the on-chip lens  451  is shielded by installing the light-shielding film  452  and a part of the light is received in the photodiode  453 . 
     A left light-shielding pixel (see  FIG. 18 ) in which the light-shielding film  452  is installed to the left and a right light-shielding pixel (not illustrated) in which the light-shielding film  452  is installed to the right are installed in parts of a pixel array unit. The right light-shielding pixel and the left light-shielding pixel are used as a pair of phase difference detection pixels. A function (separation capability) of selecting an angle of incidence of light and receiving the light is configured to be realized when light is shielded on the right side or the left side. 
     When the right light-shielding pixel and the left light-shielding pixel are installed, incident light can be separated to be received. When the photodiodes receive the light arriving from the left portion and the light arriving from the right portion, a focus position can be detected. 
     That is, at the time of rear focus or the time of front focus, an output from the photodiode in which the light is shielded on the right side does not match an output from the photodiode in which the light is shielded on the left side (outputs of the paired phase difference detection pixels match). However, at the time of focus, outputs from the two photodiodes match (the outputs of the paired phase difference detection pixels match). Detection of the focus is realized by moving the lens group  21  up to a focused position at the time of determination of the rear focus or the front focus. 
     In the image sensor  101  to which the present technology is applied, as illustrated in  FIG. 19 , photodiodes  152 - 1  to  152 - 6  disposed in the lower substrate  111 B in the second layer can be set as phase difference detection pixels. Also, as described above, the openings  302  of the aperture  301  is shifted by a shift amount in accordance with the image height with respect to a transmission pixel to be disposed. 
     Hereinafter, the photodiodes  152 - 1  to  152 - 6  are described as phase difference detection pixel groups  153 . In a case in which the phase difference detection pixel groups  153  are disposed in the lateral direction (the horizontal direction) and a case in which the phase difference detection pixel groups  153  disposed in this way are viewed from information of the image sensor  101 , the phase difference detection pixel groups  153  are disposed as in  FIG. 20 . 
       FIG. 20  illustrates a state in which nine transmission pixels (the photodiodes  133 ) are disposed in the screen image  401  and the openings  302  of the aperture  301  are installed in the transmission pixels, as in the case illustrated in  FIG. 14 . In  FIG. 20 , further, the phase difference detection pixel group  153  disposed in the lower substrate  111 B is disposed below each opening  302  (in the lower substrate  111 B). 
     In the example illustrated in  FIG. 20 , for example, the phase difference detection pixel group  153  located at the position of the opening  302 - 3  in the middle is disposed at a position at which the center of the opening  302 - 3  substantially overlaps the center of the phase difference detection pixel group  153 - 3 . 
     A phase difference detection pixel group  153 - 3 - 1  located at the position of the opening  302 - 3 - 1  located on the upward side of the middle is disposed at a position shifted upward from the opening  302 - 3 - 1 . Also, a phase difference detection pixel group  153 - 2 - 1  located at the position of the opening  302 - 2 - 1  located on the upward left side is disposed at a position shifted upward and shifted to the left from the opening  302 - 2 - 1 . 
     A phase difference detection pixel group  153 - 4 - 1  located at the position of the opening  302 - 4 - 1  located on the upward right side is disposed at a position shifted upward and shifted to the right from the opening  302 - 4 - 1 . 
     In this way, the phase difference detection pixel groups  153  are disposed at the positions shifted by the predetermined amounts from the openings  302  in accordance with the image height. 
     As illustrated in  FIGS. 19 and 20 , in a case in which the phase difference detection pixels are configured to be arranged in the lateral direction and detect a phase difference in the lateral direction, as described with reference to  FIG. 10 or 14 , it is compatible that the shift amounts are set in the horizontal direction (the lateral direction) and the positions or sizes of the openings  302  are set. 
     Also, although not illustrated, the phase difference detection pixel groups  153  may be disposed in the longitudinal direction (the vertical direction). In a case in which the phase difference detection pixel groups  153  are disposed in the longitudinal direction and a phase difference is detected in the longitudinal direction, as described with reference to  FIG. 15 or 16 , it may be compatible that the shift amounts are set in the vertical direction (the longitudinal direction) and the positions or sizes of the openings  302  are set. 
     As described in  FIG. 19 , in a case in which the phase difference detection pixel groups  153  are installed and the photodiodes  152 - 1  to  152 - 6  are disposed as the phase difference detection pixels, a graph illustrated in  FIG. 21  can be obtained by plotting the amounts of incident light received by the photodiodes  152 - 1  to  152 - 6  as a graph. 
       FIG. 21  is a graph illustrating a phase difference characteristic result. The horizontal axis represents an angle of incident light and the vertical axis represents an amount of received light. Also, numerals in the drawing indicate the photodiodes  152 - 1  to  152 - 6 . For example, “1” indicates the photodiode  152 - 1 . 
     As illustrated in  FIG. 21 , the amounts of light received by the photodiodes  152 - 1  to  152 - 6  are plotted as a graph with peaks at angles (angle of incidence) of predetermined incident light. 
     For example, for the photodiode  152 - 3 , an angle of incidence has a peak at about −20 degrees. For the photodiode  152 - 4 , an angle of incidence has a peak at about −15 degrees. 
     For example, when the angle of incidence is about −20 degrees, a phase difference can be sought using a signal which can be obtained from the photodiode  152 - 3 . When the angle of incidence is about −15 degrees, a phase difference can be sought using a signal obtained from the photodiode  152 - 4 . 
     That is, by installing the phase difference detection pixel group  153  and disposing the plurality of phase difference detection pixels, the phase difference can be sought using the signal from the photodiode  152  capable of obtaining a largest signal in accordance with an angle of the incident light and autofocus can be performed. 
     In addition, in the phase difference detection pixels, two pixels are paired. However, two pixels in one phase difference detection pixel group  153  may be selected and a phase difference may be detected. One pixel may be selected from each of two phase difference detection pixel groups  153  disposed at different positions and a phase difference may be detected from the selected two pixels. 
     In a case in which the pixels disposed in the lower substrate  111 B are set as the phase difference detection pixels, as described with reference to  FIG. 18 , the right light-shielding film pixels and the left light-shielding film pixels can also be configured using the light-shielding film  452  and can be configured to detect a phase difference. Also, even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amounts in accordance with the image height with respect to the transmission pixels to be disposed. 
       FIG. 22  is a diagram illustrating a configuration of the right light-shielding pixels and  FIG. 23  is a diagram illustrating a configuration of the left light-shielding pixels. In the right light-shielding pixels illustrated in  FIG. 22 , a light-shielding film  452 - 1  is installed in an inter-layer insulation film  202 . Of light transmitted through the opening  302 , light from the right is shielded by the light-shielding film  452 - 1  and light from the left is received by the photodiode  152 - 1  installed in the lower substrate  111 B. 
     In the left light-shielding pixels illustrated in  FIG. 23 , a light-shielding film  452 - 2  is installed in the inter-layer insulation film  202 . Of light transmitted through the opening  302 , light from the left is shielded by the light-shielding film  452 - 2  and light from the right is received by the photodiode  152 - 2  installed in the lower substrate  111 B. 
     When detection intensity of the right light-shielding pixels illustrated in  FIG. 22  and detection intensity of the left light-shielding pixels illustrated in  FIG. 23  are plotted as a graph, a graph illustrated in  FIG. 24  can be obtained. As illustrated in  FIG. 24 , a phase difference occurs between the right light-shielding pixels and the left light-shielding pixels and focus is adjusted so that the phase difference is minimized, as described with reference to  FIG. 18 . 
     In the image sensor  101  to which the present technology is applied, the light-shielding film is installed between the upper substrate  111 A and the lower substrate  111 B and the phase difference detection pixels are installed on the lower substrate  111 B. In such a configuration, it is possible to resolve a defect such as mixed color which can occur in the light-shielding pixels with the configuration illustrated in  FIG. 18 . 
     The mixed color will be described with reference to  FIG. 25 .  FIG. 25  is a diagram in which light causing mixed color is indicated by dotted arrows in the configuration of the light-shielding pixels illustrated in  FIG. 18 . Light incident via the on-chip lens  451  is shielded by the light-shielding film  452  and part of the light may be reflected and incident on the photodiodes (not illustrated) of the adjacent pixels. 
     In this way, the incident light is reflected from the light-shielding film  452  and is leaked as mixed color to adjacent pixels, and thus there is a possibility of an adverse influence on image quality. 
     However, in the image sensor  101  to which the present technology is applied, as illustrated in  FIG. 19 , no light-shielding film is installed. Therefore, it is possible to prevent the mixed color from occurring due to the light-shielding films. Also, as illustrated in  FIGS. 22 and 23 , the light-shielding film  452  is installed below the upper substrate  111 A in the first layer even in the configuration in which the light-shielding film  452  is installed. Therefore, there is no influence on an image obtained through imaging with the pixels of the upper substrate  111 A in the first layer. 
     Accordingly, even in a case in which the light-shielding film  452  is installed, it is possible to prevent the mixed color from occurring due to the light-shielding film  452 . 
     In addition, in  FIGS. 22 and 23 , the example in which the phase difference detection pixel installed in the lower substrate  111 B is configured as one photodiode  152  rather than the pixel group has been described. However, the phase difference detection pixel group  153  illustrated in  FIG. 19  may be used. 
     Also, the photodiodes  152  illustrated in  FIGS. 22 and 23  are disposed at the positions shifted in accordance with the image height with respect to the openings  302  in the horizontal direction or the vertical direction. Even in this case, in the case in which the paired phase difference detection pixels are disposed in the lateral direction, as described with reference to  FIG. 20 , it is compatible that the shift amounts are set in the horizontal direction (the lateral direction) and the positions or sizes of the openings  302  are set, as described with reference to  FIGS. 10 and 14 . 
     Also, although not illustrated, in a case in which the phase difference detection pixels are disposed in the longitudinal direction (the vertical direction) and the phase difference is detected in the longitudinal direction, it may be compatible that the shift amounts are set in the vertical direction (the longitudinal direction) and the positions or sizes of the openings  302  are set, as described with reference to  FIGS. 15 and 16 . 
     In this way, even in the case in which the pixels disposed in the lower substrates  111 B are set as the phase difference detection pixels, the openings  302  of the aperture  301  are disposed at the positions shifted in accordance with the image height with respect to the transmission pixels. Therefore, in a state in which mixed color or the like does not occur, the phase difference can be detected. Accordingly, it is possible to detect the phase difference with improved precision and it is possible to improve performance of autofocus. 
     &lt;Configuration in which a Light-shielding Film in a Grid State is Included&gt; 
     In a case in which a light-shielding film is installed in the inter-layer insulation film  202 , as illustrated in  FIG. 26 , a light-shielding film in a grid state may be installed. Even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amounts in accordance with the image height with respect to the transmission pixels to be disposed. 
     The image sensor  101  illustrated in  FIG. 26  is configured so that grid light-shielding films  501  in a grid state are installed in the inter-layer insulation film  202  and incident light is incident on the photodiodes  152  installed in the lower substrate  111 B via the grid light-shielding films  501 . 
     By installing the grid light-shielding films  501  and causing a difference in a direction of grids, it is possible to create a parallax because of the difference between the directions of the grids, which can be applied to a stereo camera or the like.  FIG. 27  is a diagram illustrating an example when the difference is caused in the direction of the grids. 
       FIG. 27  illustrates a state in which nine transmission pixels (the photodiodes  133 ) are disposed in the screen image  401  and the openings  302  of the aperture  301  are installed in the transmission pixels, as in the case illustrated in  FIG. 14 . In  FIG. 27 , the grid light-shielding films  501  are further disposed between the upper substrate  111 A and the lower substrate  111 B. 
     In the example illustrated in  FIG. 27 , the grid light-shielding films  501  of the grids in the horizontal (lateral) direction and the grid light-shielding films  501  of the grids in the vertical (longitudinal) direction are mixed. Also, the grid light-shielding films  501  of the grid in the horizontal direction and the grid light-shielding films  501  of the grids in the vertical direction are disposed to be adjacent to each other. 
     That is, the grid light-shielding film  501 - 3  located in the middle of the screen image  401  is a grid in the horizontal direction. A grid light-shielding film  501 - 2  located to the left of the screen image  401  and a grid light-shielding film  501 - 4  located to the right thereof are set as grids in the vertical direction. 
     Also, a grid light-shielding film  501 - 3 - 1  located on the upward side of the grid light-shielding film  501 - 3  located in the middle of the screen image  401  and a grid light-shielding film  501 - 3 - 2  located on the downward side of the grid light-shielding film  501 - 3  are set as grids in the vertical direction. 
     In this way, the directions of the adjacent grid light-shielding films  501  are configured to be different from each other. 
     Also, the grid light-shielding films  501  are configured to be disposed in conformity with the openings  302  shifted in accordance with the image height and disposed at positions shifted with respect to the openings  302 . In the example illustrated in  FIG. 27 , for example, the grid light-shielding film  501  located at the position of the opening  302 - 3  in the middle is disposed at a position at which the center of the opening  302 - 3  substantially overlaps the center of the grid light-shielding film  501 - 3 . 
     Also, the grid light-shielding film  501 - 3 - 1  located at the position of the opening  302 - 3 - 1  located on the upward side of the middle is disposed at a position shifted upward from the opening  302 - 3 - 1 . Also, a grid light-shielding film  501 - 2 - 1  located at the position of the opening  302 - 2 - 1  located on the upward left side is disposed at a position shifted upward and shifted to the left from the opening  302 - 2 - 1 . Also, a grid light-shielding film  501 - 4 - 1  located at the position of the opening  302 - 4 - 1  located on the upward right side is disposed at a position shifted upward and shifted to the right from the opening  302 - 4 - 1 . 
     In this way, the grid light-shielding films  501  are disposed at the positions shifted by the predetermined amounts from the openings  302  in accordance with the image height. 
     In a case in which the grid light-shielding films  501  are installed, it is compatible that the shift amounts are set in the horizontal direction (the lateral direction), the vertical direction (the longitudinal direction), and the diagonal direction in regard to the positions or sizes of the openings  302 , as described with reference to  FIG. 17 . 
     The case in which the shapes of the grids of the grid light-shielding films  501  are in the longitudinal direction or the lateral direction illustrated in  FIG. 27  has been described as an example, but other shapes may be used. For example, as illustrated in  FIG. 28 , a grid shape in a diagonal direction may be used. 
     The direction of the grids of the grid light-shielding films  501  illustrated in  FIG. 28  is oriented to the downward right side at 45 degrees (hereinafter referred to as the downward right direction) or is oriented to the downward left side at 45 degrees (hereinafter referred to as the downward left direction). That is, in the example illustrated in  FIG. 28 , the grid light-shielding films  501  in the downward right direction and the grid light-shielding films  501  in the downward left direction are mixed. 
     The grid light-shielding films  501  of the grids in the downward right direction and the grid light-shielding films  501  of the grids in the downward left direction are disposed to be adjacent to each other. That is, the grid light-shielding film  501 - 3  located in the middle of the screen image  401  is a grid in the downward left direction. The grid light-shielding film  501 - 2  located to the left of the screen image  401  and the grid light-shielding film  501 - 4  located to the right thereof are set as grids in the downward right direction. 
     Also, grid light-shielding film  501 - 3 - 1  located on the upward side of the grid light-shielding film  501 - 3  located in the middle of the screen image  401  and the grid light-shielding film  501 - 3 - 2  located on the downward side thereof are set as grids in the downward right direction. 
     In this way, the directions of the grids of the adjacent grid light-shielding films  501  are set to be different from each other. Also, as in the case illustrated in  FIG. 27 , the grid light-shielding films  501  are disposed at the positions shifted by the predetermined amounts in accordance with the image height with respect to the openings  302 . 
     Further, as illustrated in  FIG. 29 , the grid light-shielding films  501  in the horizontal direction, the grid light-shielding films  501  in the vertical direction, the grid light-shielding films  501  in the downward right direction, and the grid light-shielding films  501  in the downward left direction can also be configured to be mixed. 
     In the example illustrated in  FIG. 29 , the grid light-shielding film  501 - 3  located in the middle of the screen image  401  is a grid in the downward left direction, the grid light-shielding film  501 - 2  located on the left side thereof is a grid in the vertical direction, and the grid light-shielding film  501 - 4  located on the right side is a grid in the horizontal direction. 
     Also, a grid light-shielding film  501 - 3 - 1  located on the upward side of the grid light-shielding film  501 - 3  located in the middle of the screen image  401  and a grid light-shielding film  501 - 3 - 2  located on the downward side of the grid light-shielding film  501 - 3  are set as grids in the lower right direction. 
     Also, a grid light-shielding film  501 - 2 - 1  located on the upper left side of the grid light-shielding film  501 - 3  located in the middle of the screen image  401  and a grid light-shielding film  501 - 2 - 2  located on the lower left side of the grid light-shielding film  501 - 3  are set as grids in the horizontal direction. 
     Also, a grid light-shielding film  501 - 4 - 1  located on the upper right side of the grid light-shielding film  501 - 3  located in the middle of the screen image  401  and a grid light-shielding film  501 - 4 - 2  located on the lower right side of the grid light-shielding film  501 - 3  are set as grids in the vertical direction. 
     Also in the case of  FIG. 29 , the directions of the adjacent grid light-shielding films  501  are set to be different from each other. Also, as in the case illustrated in  FIG. 27 , the grid light-shielding films  501  are disposed at the positions shifted by the predetermined amounts in accordance with the image height with respect to the openings  302 . 
     In this way, in a case in which the grid light-shielding films  501  with the grid shapes are disposed in the image sensor  101 , a parallax is created because of the difference between the directions of the grids, which can be applied to a stereo camera or the like. 
     Even in a case in which the grid light-shielding films  501  are installed as in the case of the phase difference detection pixels described with reference to  FIGS. 19 to 25 , the incident light is reflected from the grid light-shielding films  501  and is leaked as mixed color to adjacent pixels, and thus there is a possibility of an adverse influence on image quality. 
     In the image sensor  101  to which the present technology is applied, as illustrated in  FIG. 26 , the grid light-shielding films  501  are installed below the upper substrate  111 A in the first layer. Therefore, there is no influence on an image which can be obtained in the upper substrate  111 A in the first layer. Accordingly, even in a case in which the grid light-shielding films  501  are installed, it is possible to prevent mixed color from occurring due to the grid light-shielding films  501 . 
     Also, even in the case in which the grid light-shielding films  501  are installed, the openings  302  of the aperture  301  are disposed at the positions shifted in accordance with the image height with respect to the transmission pixels. Therefore, in a state in which the mixed color or the like does not occur, light can be shielded by the grid light-shielding films  501 . 
     &lt;Configuration in which Narrow-band Filter is Included&gt; 
     A configuration in which a filter is installed in the inter-layer insulation film  202  can be realized.  FIG. 30  illustrates a configuration of the image sensor  101  in which a narrow-band filter is installed as a filter. The image sensor  101  illustrated in  FIG. 30  is configured so that a narrow-band filter  551  is installed in the inter-layer insulation film  202  and incident light is incident on the photodiode  152  installed in the lower substrate  111 B via the narrow-band filter  551 . 
     Even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amount in accordance with the image height with respect to the transmission pixels to be disposed. 
     By installing the narrow-band filter  551  in the inter-layer insulation film  202 , a wavelength which is desired to be analyzed with the narrow-band filter  551  can be selected from the light transmitted through a predetermined pixel of the upper substrate  111 A and the selected light can be received with the photodiode  152 . That is, it is possible to realize the image sensor  101  capable of selectively extracting the wavelength which is desired to be analyzed. 
     In the upper substrate  111 A, the pixels are disposed in a 2-dimensional array form. Then, of the pixels disposed in the 2-dimensional array form, the openings  302  are installed in predetermined pixels set as the transmission pixels and the narrow-band filters  551  are installed in the locations of the openings  302 . Accordingly, the plurality of narrow-band filters  551  are installed in the image sensor  101 . 
     All the plurality of installed narrow-band filters  551  may be set as the same filters. Also, by setting the plurality of installed narrow-band filters  551  as filter that extract different wavelengths, it is possible to realize the image sensor  101  capable of extracting multi-spectrum or hyper-spectrum data. 
     Even in this case, since the narrow-band filters  551  are installed between the upper substrate  111 A and the lower substrate  111 B, the narrow-band filters  551  does not affect an image captured by the pixels of the upper substrate  111 A and it is possible to prevent image quality from deteriorating. 
     &lt;Configuration in which Plasmon Filter is Included&gt; 
       FIG. 31  illustrates a configuration of the image sensor  101  in which a plasmon filter is installed as a filter. The image sensor  101  illustrated in  FIG. 31  is configured so that a plasmon filter  601  is installed in the inter-layer insulation film  202  and incident light is incident on the photodiode  152  installed in the lower substrate  111 B via the plasmon filter  601 . 
     Even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amount in accordance with the image height with respect to the transmission pixels to be disposed. 
     The plasmon filter  601  is a filter that performs spectroscopy and a filter in which a plasmon resonator is used as a filter. A configuration of the plasmon filter  601  is illustrated in  FIG. 32 . The plasmon resonator is a sub-wavelength structure formed by performing minute processing on a thin film formed of a conductor material (specifically gold, silver, copper, or the like; particularly aluminum, nickel, or the like is appropriate). 
     The plasmon resonator has a resonance wavelength decided in accordance with a physical property or a pattern period of a conductor, an opening diameter, a dot size, a film thickness, a medium around the structure, or the like. A basic structure of the plasmon resonator is a hole array structure and is a structure in which holes (through holes  602  or non-through holes  602 ) with a diameter less than a detection wavelength are disposed in a 2-dimensional array form. The holes are filled with a dielectric material. Also, a considerably preferable disposition of the holes is a honeycomb or an orthogonal matrix. A structure which has periodicity in another disposition can be applied. 
     For example, the plasmon filter  601  illustrated in  FIG. 32  is configured by a plasmon resonator in which the through holes  602  are disposed in a conductor thin film in a honeycomb form. An opening diameter of the through hole  602  may be less than the wavelength of light which is desired to be transmitted. For example a diameter of about 100 nm is considered. 
     A transmission wavelength in which light is transmitted through the plasmon filter  601  is set by adjusting an interval between the adjacent through holes  602  in the plasmon filter  601 . The interval is considerably preferable in a range from half of an effective wavelength of an electromagnetic wave in a medium to about one wavelength. Specifically, about 150 nm to 1000 nm is considered. 
     By installing the plasmon filter  601  in the inter-layer insulation film  202 , a wavelength which is desired to be analyzed with the plasmon filter  601  can be selected from the light transmitted through a predetermined pixel of the upper substrate  111 A and the selected light can be received with the photodiode  152 . That is, it is possible to realize the image sensor  101  capable of selectively extracting the wavelength which is desired to be analyzed. 
     In the upper substrate  111 A, the pixels are disposed in a 2-dimensional array form. Then, of the pixels disposed in the 2-dimensional array form, the openings  302  are installed in predetermined pixels set as the transmission pixels and the plasmon filters  601  are installed in the locations of the openings  302 . Accordingly, the plurality of plasmon filters  601  are installed in the image sensor  101 . 
     All the plurality of installed plasmon filters  601  may be set as the same filters. Also, by setting the plurality of installed plasmon filters  601  as filter that extract different wavelengths, it is possible to realize the image sensor  101  capable of extracting multi-spectrum or hyper-spectrum data. 
     Even in this case, since the plasmon filters  601  are installed between the upper substrate  111 A and the lower substrate  111 B, the plasmon filters  601  does not affect an image captured by the pixels of the upper substrate  111 A and it is possible to prevent image quality from deteriorating. 
     Also, even in the case in which the plasmon filters  601  are installed, the openings  302  of the aperture  301  are disposed at the positions shifted in accordance with the image height with respect to the transmission pixels. Therefore, in a state in which the mixed color or the like does not occur, spectroscopy can be performed by the plasmon filters  601 . 
     &lt;Configuration in which Fabry-Pérot Interferometer is Included&gt; 
       FIG. 33  illustrates a configuration of the image sensor  101  in which a Fabry-Pérot interferometer is installed as a filter. The image sensor  101  illustrated in  FIG. 33  is configured so that a Fabry-Pérot interferometer  651  is installed in the inter-layer insulation film  202  and incident light is incident on the photodiode  152  installed in the lower substrate  111 B via the Fabry-Pérot interferometer  651 . 
     Even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amount in accordance with the image height with respect to the transmission pixels to be disposed. 
     As illustrated in  FIG. 34 , the Fabry-Pérot interferometer  651  is an optical device that is configured to include two semi-transparent mirrors  652  and  653  and in which the two semi-transparent mirrors  652  and  653  are disposed in parallel to face each other. The semi-transparent mirrors  652  and  653  are finished as reflective surfaces with high reflectance and slight transmittance. 
     Light incident from one side (in the drawing, the upper side) of the Fabry-Pérot interferometer  651  is reflected between both reflection surfaces several times, reciprocate, and interfere in each other. The light transmitted through the semi-transparent mirror  653  becomes interference light with a considerable length due to light reciprocating several times with a constant optical path difference. Accordingly, when this is used as a spectrometer, a considerably high resolution can be obtained. 
     By installing the Fabry-Pérot interferometer  651  in the inter-layer insulation film  202 , a wavelength which is desired to be analyzed with the Fabry-Pérot interferometer  651  can be selected from the light transmitted through the transmission pixel of the upper substrate  111 A and the selected light can be received with the photodiode  152 . That is, it is possible to realize the image sensor  101  capable of selectively extracting the wavelength which is desired to be analyzed. 
     In the upper substrate  111 A, the pixels are disposed in a 2-dimensional array form. Then, of the pixels disposed in the 2-dimensional array form, the openings  302  are installed in predetermined pixels set as the transmission pixels and the Fabry-Pérot interferometers  651  are installed in the locations of the openings  302 . Accordingly, the plurality of Fabry-Pérot interferometers  651  are installed in the image sensor  101 . 
     All the plurality of installed Fabry-Pérot interferometers  651  may be set as the same filters. Also, by setting the plurality of installed Fabry-Pérot interferometers  651  as filter that extract different wavelengths, it is possible to realize the image sensor  101  capable of extracting multi-spectrum or hyper-spectrum data. 
     Even in this case, since the Fabry-Pérot interferometers  651  are installed between the upper substrate  111 A and the lower substrate  111 B, the Fabry-Pérot interferometers  651  does not affect an image captured by the pixels of the upper substrate  111 A and it is possible to prevent image quality from deteriorating. 
     Also, even in the case in which the Fabry-Pérot interferometers  651  are installed, the openings  302  of the aperture  301  are disposed at the positions shifted in accordance with the image height with respect to the transmission pixels. Therefore, in a state in which the mixed color or the like does not occur, spectroscopy can be performed by the Fabry-Pérot interferometers  651 . 
     &lt;Configuration in which TOF Type Sensor is Included&gt; 
     The pixels disposed in the lower substrate  111 B may be used as a time to flight (TOF) type sensor. Even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amounts in accordance with the image height with respect to the transmission pixels to be disposed. 
     In the image sensor  101  illustrated in  FIG. 35 , the photodiodes  152  installed in the lower substrate  111 B are configured as a TOF type sensor. For example, the TOF type sensor is a sensor in which two pixels are paired and a distance is measured using the two pixels. 
     The TOF type sensor is a sensor that measures a distance to a target object by measuring a time in which light emitted from the TOF type sensor arrives at the target object, is reflected, and returns. For example, the TOF type sensor operates at a timing illustrated in  FIG. 36 . 
     For example, here, the target object is irradiated with irradiated light by a predetermined time, here, a pulse emission time Tp. The emitted irradiated light arrives at the target object, is reflected, and returns. The reflected light is received by the photodiodes  152 . As illustrated in  FIG. 36 , a time in which irradiation of the irradiated light starts and the reflected light is received is a time in accordance with the distance to the target object. 
     A first photodiode  152  receives light by the pulse emission time Tp from a time point at which the irradiation of the irradiated light starts. The received light is background light and reflected light. A signal n 0  is acquired from an amount of received light accumulated when the light is received once. 
     A second photodiode  152  receives light by the pulse emission time Tp from a time point at which the reception of the light by the first photodiode  152  ends. The received light is background light and reflected light. A signal n 1  is acquired from an amount of received light accumulated when the light is received once. 
     In this way, the signals n 0  and n 1  are acquired by performing driving so that a phase of an accumulation timing is completely reversed. The signals N 0  and N 1  are acquired by repeating the driving a plurality of times and accumulating and integrating the amounts of light. A distance D is calculated from the signals N 0  and N 1  which can be obtained in this way. 
     The signals N 0  and N 1  (signals n 0  and n 1 ) also include signals accumulated by receiving the background light. Therefore, since the signals remain from the reflected light excluding the background light, a signal N 2  is acquired by accumulating and integrating the amounts of background light. 
     The distance D is calculated using the signals N 0 , N 1 , and N 2  acquired in this way by the following Equations (1) and (2). 
     
       
         
           
             
               
                 
                   
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     In Equations (1) and (2), D indicates a distance, c indicates a high speed, and Tp indicates a pulse emission time. 
     The photodiodes  152  disposed in the lower substrate  111 B can be used as the TOF type sensor and configured to measure the distance D to a target object using the TOF type sensor. According to the present technology, there is no influence on the upper substrate  111 A since the TOF type sensor is disposed in the lower substrate  111 B. Accordingly, it is possible to realize the image sensor  101  capable of measuring the distance without having the influence on an image which can be obtained with the pixels of the upper substrate  111 A. 
     Also, the sensor of the upper substrate  111 A and the sensor of the lower substrate  111 B can be separate sensors. That is, it is possible to realize the image sensor  101  that includes two independent sensors. 
     As illustrated in  FIG. 37 , in the image sensor  101  to which the present technology is applied, light transmitted through the upper substrate  111 A is received by the photodiodes  152  disposed in the lower substrate  111 B. In a case in which the upper substrate  111 A is formed of, for example, silicon, a visible light region with a short wavelength is absorbed. Near infrared light near 850 nm is used as irradiation light of the TOF type sensor in many cases. 
     Because of this fact, from this point, it is advantageous that the TOF type sensor in which light arriving at the lower substrate  111 B is light from which the visible light region with the short wavelength region is excluded and the near infrared light near 850 nm is used in many cases is installed in the lower substrate  111 B even when no filter or the like is used. 
     Also, even in the case in which the TOF type sensors are installed, the openings  302  of the aperture  301  are disposed at the positions shifted in accordance with the image height with respect to the transmission pixels. Therefore, in a state in which the mixed color or the like does not occur, a distance can be measured by the TOF type sensor. 
     &lt;Configuration in which LFC Type Sensor is Included&gt; 
     The pixels disposed in the lower substrate  111 B may be used as a light field camera (LFC). Even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amounts in accordance with the image height with respect to the transmission pixels to be disposed. 
     In the image sensor  101  illustrated in  FIG. 37 , the photodiodes  152  installed in the lower substrate  111 B configure a light field camera. 
     The light field camera is a camera that acquires multiple rays as light fields (ray space) and performs a kind of image processing on a set of the rays to obtain a final image. As a main function of the light field camera, there is a refocusing function of generating an image in which a camera focal distance is changed through post-processing after photographing. The light field camera can be configured in the lower substrate  111 B. 
     In the light field camera, it is necessary to receive light transmitted through one on-chip lens  131  with the plurality of pixels. A configuration in which light is received with two pixels of the photodiodes  152 - 1  and  152 - 2  is illustrated in  FIG. 37 , but the number of pixels equal to or greater than 4×4 is considered. Also, when light transmitted through one on-chip lens  131  (transmission pixel) is received with a plurality of pixels (photodiodes  152 ), stereo images can be obtained by the number of pixels. By obtaining the plurality of stereo images, it is possible to realize the refocusing function, as described above. 
     In this way, according to the present technology, the photodiodes  152  disposed in the lower substrate  111 B can be configured to be used as the light field camera. According to the present technology, there is no influence on the upper substrate  111 A since the light field camera is disposed in the lower substrate  111 B. Accordingly, it is possible to realize the image sensor  101  capable of measuring a distance without having the influence on an image which can be obtained with the pixels of the upper substrate  111 A. 
     Also, the sensor of the upper substrate  111 A and the sensor of the lower substrate  111 B can be separate sensors. That is, it is possible to realize the image sensor  101  that includes two independent sensors. 
     Also, even in the case in which the light field cameras are installed, the openings  302  of the aperture  301  are disposed at the positions shifted in accordance with the image height with respect to the transmission pixels. Therefore, in a state in which the mixed color or the like does not occur, images can be captured by the light field cameras. 
     &lt;Configuration in which Image is Captured in Two Layers&gt; 
     The pixels disposed in the lower substrate  111 B may be used as pixels with which a normal image is captured as in the pixels disposed in the upper substrate  111 A. Even in such a configuration, as described above, the openings  302  of the aperture  301  are shifted by the shift amounts according to the image height with respect to the transmission pixels to be disposed. 
     In the image sensor  101  illustrated in  FIG. 38 , the photodiodes  152  installed in the lower substrate  111 B are used as pixels with which a normal image is captured. 
     That is, the image sensor  101  illustrated in  FIG. 38  is configured so that the same image can be captured with the upper substrate  111 A and the lower substrate  111 B. Even in such a configuration, an image captured with the lower substrate  111 B may be used for an image displayed on the display unit  25  (see  FIG. 1 ) of the image sensor  10 . 
     On the display unit  25 , a preview image is displayed at the time of photographing of an image. An image in which an image captured with the pixels of the upper substrate  111 A is decimated is considered to be used as the preview image. 
     As in the embodiment, by realizing a configuration in which imaging is performed with the pixels in two layers, it is possible to perform separate uses in which an image captured with the pixels in one layer is set as a preview image and an image captured with the pixels in the other layer is set as a recording image. Here, the example in which the recording image is captured with the pixels of the upper substrate  111 A and the image for the preview image is captured with the pixels of the lower substrate  111 B has been described. 
     Also, by realizing the configuration in which imaging is performed with the pixels in two layers, it is possible to set an image captured with the pixels in one layer as a moving image and set an image captured with the pixels in the other layer as a still image. For example, it is possible to realize a configuration in which a still image is captured with the pixels of the upper substrate  111 A and a moving image is captured with the pixels of the lower substrate  111 B. 
     Also, it is also possible to simultaneously image light with different wavelengths so that an image of the visible light is captured with the pixels of the upper substrate  111 A and an image of the near infrared light is simultaneously captured with the pixels of the lower substrate  111 B. 
     Since the images are captured with the pixels disposed in the different layers, both good images can be acquired without being mutually affected. 
     Also, even in a case in which images are captured with the pixels disposed in two layers, as in the foregoing case, the openings  302  of the aperture  301  are disposed at the positions shifted in accordance with the image height with respect to the transmission pixels. Therefore, the image captured with the pixels of each layer can be obtained in a state in which mixed color or the like does not occur. 
     &lt;Other Configurations&gt; 
     In the above-described embodiment, the example in which the image sensor  101  is configured with two layers of the upper substrate  111 A and the lower substrate  111 B has been described. However, as illustrated in  FIG. 39 , the image sensor may be configured with three layers. In the example illustrated in  FIG. 38 , the image sensor  101  has a configuration of three layers in which a substrate  701  is installed between the upper substrate  111 A and the lower substrate  111 B. 
     In this way, the present technology can be applied to a multi-layered structure such as a 3-layered structure without being limited to two layers. Also, it is also possible to realize a configuration in which a through port is formed in silicon and sufficient light is transmitted up to a lower layer, for example, in a case in which the sufficient light is not transmitted up to the lower layer due to absorption of the light by the silicon in a halfway layer. 
     Also, even in the case of two layers, as illustrated in  FIG. 40 , a through port may be formed. In the image sensor  101  illustrated in  FIG. 40 , a through port  702  is formed in silicon of the upper substrate  111 A set as a transmission pixel. By forming the through port  702 , it is easy for light to be transmitted up to the lower substrate  111 B via the through port  702 . For example, it is possible to realize the image sensor  101  in which the visible light or the like with a short wavelength is also easily received with the lower substrate  111 B. 
     The color of the on-chip color filter  132  of the transmission pixel may be one of so-called RGB, red, green, and blue or may be further white (W) or transparent. In particular, in a case in which the color of the on-chip color filter is set to be white (transparent), detection can be performed with high sensitivity even in the pixels (sensor) in second layer transition. 
     In the above-described embodiment, the example in which the openings  302  of the aperture  301  are configured to be planar (2-dimensional) has been described. However, as illustrated in  FIG. 41 , the openings may be configured to be 3-dimensional. In the openings  302  illustrated in  FIG. 41 , metal is formed in the upward direction in the drawing and metal is formed not only in the lateral direction (the horizontal direction) but also in the longitudinal direction (the vertical direction). 
     In this way, by configuring the openings  302  to be 3-dimensional, it is possible to further suppress mixed color from the adjacent pixels. 
     In addition, in the above-described configuration, the aperture  301  formed of metal has been described. However, the aperture can also be formed of a material other than metal as long as light is not transmitted through the material. Here, in a case in which the aperture  301  is installed as a part of the multilayer wiring layer  201 , it is necessary to have conductivity. 
     According to the present technology, as described above, by configuring the openings  302  of the aperture  301  (the multilayer wiring layer  201 ) to be left-right asymmetric, it is possible to realize a configuration in which unnecessary light of mixed color or the like from the adjacent pixels can be cut and necessary light can be further acquired. Also, it is also possible to correspond to even light of a high angle of incidence. 
     Also, in various sensors and, particularly, in phase difference sensors, it is possible to generate a sensor in which a separation ratio is high up to a high angle of incidence. 
     &lt;Usage Examples of Image Sensor&gt; 
       FIG. 42  illustrates the usage examples of the above-described image sensor and an electronic device including an image sensor. 
     The above-described image sensor can be used for, for example, various cases in which light such as visible light, infrared light, ultraviolet light, or X-rays is detected as follows.
         Devices that take images used for viewing, such as a digital camera and a portable appliance with a camera function.   Devices used for traffic, such as an in-vehicle sensor that takes images of the front and the back of a car, surroundings, the inside of the car, and the like, a monitoring camera that monitors travelling vehicles and roads, and a distance sensor that measures distances between vehicles and the like, which are used for safe driving (e.g., automatic stop), recognition of the condition of a driver, and the like.   Devices used for home electrical appliances, such as a TV, a refrigerator, and an air conditioner, to takes images of a gesture of a user and perform appliance operation in accordance with the gesture.   Devices used for medical care and health care, such as an endoscope and a device that performs angiography by reception of infrared light.   Devices used for security, such as a monitoring camera for crime prevention and a camera for personal authentication.   Devices used for beauty care, such as skin measurement equipment that takes images of the skin and a microscope that takes images of the scalp.   Devices used for sports, such as an action camera and a wearable camera for sports and the like.   Devices used for agriculture, such as a camera for monitoring the condition of the field and crops.       

     Further, in the present specification, a system means the whole apparatus configured by a plurality of devices. 
     In addition, the effects described in the present specification are not limiting but are merely examples, and there may be additional effects. 
     An embodiment of the disclosure is not limited to the embodiments described above, and various changes and modifications may be made without departing from the scope of the disclosure. 
     Additionally, the present technology may also be configured as below. 
     (1) 
     An image sensor, 
     in which photoelectric conversion layers including photoelectric conversion units separated in units of pixels are stacked in two or more layers, 
     the image sensor is configured to include a state in which light incident on one pixel in a first photoelectric conversion layer closer to an optical lens is received by the photoelectric conversion unit in a second photoelectric conversion layer distant from the optical lens, 
     the image sensor includes a light-shielding layer configured to shield light transmitted through the first photoelectric conversion layer, between the first photoelectric conversion layer and the second photoelectric conversion layer, 
     the light-shielding layer has an opening to transmit the light from the first photoelectric conversion layer to the second photoelectric conversion layer, and 
     the openings are made to be asymmetric with respect to the pixel in the first photoelectric conversion layer. 
     (2) 
     The image sensor according to (1), 
     in which the openings have different asymmetry in accordance with an image height of the optical lens. 
     (3) 
     The image sensor according to (1) or (2), 
     in which asymmetry of the openings increases when an image height of the optical lens is raised. 
     (4) 
     The image sensor according to any of (1) to (3), 
     in which sides that form the opening are disposed at positions shifted from sides that form a pixel in the first photoelectric conversion layer in which the opening is located, and 
     among the sides that form the opening, a first side located on a central side of the optical lens and a second side different from the first side are shifted by different shift amounts. 
     (5) 
     The image sensor according to (4), 
     in which the shift is performed in a horizontal direction. 
     (6) 
     The image sensor according to (4), 
     in which the shift is performed in a horizontal direction and a diagonal direction. 
     (7) 
     The image sensor according to (4), 
     in which the shift is performed in a vertical direction. 
     (8) 
     The image sensor according to (4), 
     in which the shift is performed in a vertical direction and a diagonal direction. 
     (9) 
     The image sensor according to (4), 
     in which the shift is performed in at least one of a horizontal direction, a vertical direction, and a diagonal direction. 
     (10) 
     The image sensor according to any of (1) to (9), 
     in which a pixel of the photoelectric conversion unit in the second photoelectric conversion layer is a phase difference detection pixel. 
     (11) 
     The image sensor according to any of (1) to (9), further including: 
     a light-shielding unit configured to shield light transmitted through the opening, between the light-shielding layer and the second photoelectric conversion layer, 
     in which the pixel of the photoelectric conversion unit in the second photoelectric conversion layer is configured in a state in which the light is half shielded by the light-shielding unit, and 
     the pixel of the photoelectric conversion unit in the second photoelectric conversion layer is set as a phase difference detection pixel. 
     (12) 
     The image sensor according to any of (1) to (9), further including: 
     a light-shielding unit formed between the first photoelectric conversion layer and the second photoelectric conversion layer in a grid state in which the light transmitted through the first photoelectric conversion layer is shielded. 
     (13) 
     The image sensor according to (12), 
     in which grids of the light-shielding units disposed to be adjacent to each other are grids in different directions. 
     (14) 
     The image sensor according to any of (1) to (9), further including: 
     a narrow-band filter between the first photoelectric conversion layer and the second photoelectric conversion layer, 
     in which the light transmitted through the first photoelectric conversion layer arrives at the photoelectric conversion unit of the second photoelectric conversion layer via the filter. 
     (15) 
     The image sensor according to any of (1) to (9), further including: 
     a plasmon filter between the first photoelectric conversion layer and the second photoelectric conversion layer, 
     in which the light transmitted through the first photoelectric conversion layer arrives at the photoelectric conversion unit of the second photoelectric conversion layer via the plasmon filter. 
     (16) 
     The image sensor according to any of (1) to (9), further including: 
     a Fabry-Pérot interferometer between the first photoelectric conversion layer and the second photoelectric conversion layer, 
     in which the light transmitted through the first photoelectric conversion layer arrives at the photoelectric conversion unit of the second photoelectric conversion layer via the Fabry-Pérot interferometer. 
     (17) 
     The image sensor according to any of (1) to (9), 
     in which the photoelectric conversion unit in the second photoelectric conversion layer forms a time of flight (TOF) type sensor. 
     (18) 
     The image sensor according to any of (1) to (9), 
     in which the photoelectric conversion unit in the second photoelectric conversion layer forms a light field camera. 
     (19) 
     The image sensor according to any of (1) to (9), 
     in which the photoelectric conversion unit in the second photoelectric conversion layer is used as a sensor that images a subject and acquires an image. 
     (20) 
     An electronic device including: 
     an image sensor, 
     in which photoelectric conversion layers including photoelectric conversion units separated in units of pixels are stacked in two or more layers, 
     the image sensor is configured to include a state in which light incident on one pixel in a first photoelectric conversion layer closer to an optical lens is received by the photoelectric conversion unit in a second photoelectric conversion layer distant from the optical lens, 
     the image sensor includes a light-shielding layer configured to shield light transmitted through the first photoelectric conversion layer, between the first photoelectric conversion layer and the second photoelectric conversion layer, 
     the light-shielding layer has an opening to transmit the light from the first photoelectric conversion layer to the second photoelectric conversion layer, and 
     the openings are made to be asymmetric with respect to the pixel in the first photoelectric conversion layer. 
     REFERENCE SIGNS LIST 
     
         
           10  imaging device 
           21  lens group 
           22  image sensor 
           101  image sensor 
           102  optical lens 
           111 A upper substrate 
           111 B lower substrate 
           131  on-chip lens 
           132  on-chip color filter 
           133  photodiode 
           151  pixel group 
           152  photodiode 
           301  aperture 
           302  opening