JP7330687B2 - Imaging element and imaging device - Google Patents

Description

The present invention particularly relates to an imaging element and an imaging apparatus for performing phase difference detection by pupil division.

In imaging devices such as digital cameras and digital video cameras, which shoot scenes by focusing light from a subject on an imaging element with two-dimensional array of imaging pixels, in recent years, the pixel size has been reduced due to the increase in the number of pixels. It is important to improve the photodetection sensitivity in In particular, there are many imaging devices that perform focus detection by means of an imaging surface phase difference method, in which phase difference detection is performed by dividing the pupil of the imaging optical system. . Therefore, various proposals have been made to obtain an imaging device with high photodetection sensitivity.

In Japanese Unexamined Patent Application Publication No. 2004-100000, light is shielded in an optical waveguide so as to surround each pixel in order to prevent sensitivity deterioration and color mixing between pixels due to leakage of light between pixels, and to prevent loss of phase difference information. Pixel configurations that introduce walls have been proposed. Patent Document 2 discloses a configuration in which an optical waveguide is formed from the vicinity of the surface of the photoelectric conversion portion to the upper end of the insulating film. It is said that it is avoiding becoming.

Furthermore, as the pixel size is reduced due to the increase in the number of pixels, it is becoming more difficult to efficiently introduce light into a narrow light receiving region as the wavelength of the light is longer. As a means for dealing with such a situation, Patent Document 3 proposes a configuration in which the refractive index of the non-reflective film on the bottom surface of the optical waveguide of the pixel corresponding to each color is adjusted to suppress variations in light receiving sensitivity between colors. It is

JP 2015-167219 A JP 2015-162562 A JP 2015-69992 A

However, light may leak from the periphery of the pixel or from adjacent pixels, which may disturb the electromagnetic field distribution within the pixel or change the light receiving efficiency depending on the color as the pixel size is reduced. In such a case, the focus detection accuracy in the imaging plane phase difference method is lowered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an imaging device with high photodetection sensitivity and an imaging apparatus using the same.

An image pickup device according to the present invention is an image pickup device in which a plurality of image pickup pixels are arranged two-dimensionally, and each of the plurality of image pickup pixels includes a plurality of electrically divided photoelectric conversion units and a microlens. and a light shielding wall surrounding the imaging pixel between the photoelectric conversion unit and the microlens, wherein the width of the surface of the light shielding wall on the microlens side is the width of the surface of the light shielding wall on the photoelectric conversion unit side. The width of the light shielding wall is larger than the width of the light shielding wall, and the area of the corner portion of the surface of the light shielding wall on the photoelectric conversion unit side is smaller than the area of the gap of the microlens.

According to the present invention, it is possible to provide an imaging device with high photodetection sensitivity and an imaging device using the same, which enhances focus detection accuracy by the imaging plane phase difference method.

FIG. 2 is a schematic diagram showing an image sensor and a basic pixel group of 2 rows and 2 columns, which is a part thereof. 4 is a schematic diagram showing a cross section of an imaging pixel in the first embodiment; FIG. FIG. 10 is a diagram for explaining a detailed shape of an inter-pixel light shielding wall; FIG. 11 is a diagram for explaining another example of the inter-pixel light shielding wall; FIG. 4 is a diagram for explaining a gap of a top microlens; FIG. 3 is a schematic diagram showing a correspondence relationship between an image sensor and pupil division; FIG. 4 is a diagram for explaining an outline of a relationship between an image shift amount between parallax images and a defocus amount; 2 is a block diagram showing an internal configuration example of an imaging device; FIG. FIG. 4 is a schematic diagram showing a cross section of an imaging pixel having an edge region in an optical waveguide; FIG. 4 is a schematic diagram showing a cross section of an imaging pixel having an edge region in an optical waveguide at an image plane position away from the central position; It is a schematic diagram showing the cross section of the imaging pixel in 2nd Embodiment. FIG. 4 is a diagram for explaining a propagation path of light incident on a pixel with or without a light shielding portion; It is a schematic diagram showing the cross section of the imaging pixel in 3rd Embodiment. 2 is a block diagram showing an internal configuration example of an imaging device; FIG. FIG. 3 is a schematic diagram showing a basic pixel group of RGB pixels; FIG. 4 is a diagram for explaining a cross section of an imaging pixel and a light propagation path; FIG. 4 is a diagram for explaining an outline of a correspondence relationship between a pixel structure and pupil division; FIG. 4 is a diagram for explaining a beam waist radius of light; FIG. 4 is a diagram for explaining directions in which crosstalk occurs among R, G, and B pixels;

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings. In this embodiment, an example in which the horizontal size of the effective pixel area is 22.32 mm, the vertical size is 14.88 mm, the number of effective pixels in the horizontal direction is 6000, and the number of effective pixels in the vertical direction is 4000 will be described.

FIG. 1A is a schematic diagram showing a basic pixel group 101 of 2 rows and 2 columns as part of a plurality of imaging pixels arranged on an imaging surface of an imaging element. The basic pixel group 101 includes an imaging pixel 102 having spectral sensitivity in a wavelength band corresponding to red, an imaging pixel 103 having spectral sensitivity in a wavelength band corresponding to blue, and two imaging pixels 104 having spectral sensitivity in a wavelength band corresponding to green. , 105. In the following description, the imaging plane on which a plurality of imaging pixels are arranged is parallel to the xy plane, and the direction perpendicular thereto is the z direction.

FIG. 1B is a schematic diagram of the imaging element 106 viewed from above the imaging surface. As shown in FIG. 1B, the basic pixel group 101 is arranged two-dimensionally on the imaging surface. Here, the basic configuration of the imaging pixels 102 to 105 forming the basic pixel group 101 is the same except for color filters that transmit light of a specific wavelength region. Therefore, when describing the configuration of the image pickup pixel, the image pickup pixel 102 will be described as a representative.

FIG. 2 is a schematic diagram showing a cross section parallel to the zx plane in the imaging pixel 102 in FIG. 1A in this embodiment. An n-type silicon substrate 201 is provided with a photoelectric conversion section 202 formed by ion implantation from the surface side. The photoelectric conversion unit 202 is electrically separated into sub-photoelectric conversion units 202a and 202b by a central separation region 211, and pixel regions corresponding to each are sub-pixels. Ions are implanted from the -z direction in FIG. 2, and after thinning the back surface of the silicon substrate 201 (+z side in FIG. 2), optical structures such as microlenses are arranged on the back surface side.

An insulating portion 204 made of silicon oxide (SiO _x ) is formed on the back side of the silicon substrate 201 , and an intralayer microlens (inner lens) 205 , a color filter 207 and a top microlens 209 are formed thereabove. It is Inter-pixel light shielding walls 203 and 210 are light shielding walls for shielding light between pixels, and are arranged so as to surround each pixel. The inter-pixel light shielding wall 203 has a constant wall width in the z direction, whereas the inter-pixel light shielding wall 210 is formed so that the wall width increases toward the top. That is, the width of the surface (uppermost surface) of the inter-pixel light shielding wall on the top microlens side is larger than the width of the surface (lowermost surface) on the photoelectric conversion unit side. With this configuration, leaked light and stray light that cause adverse effects can be eliminated from above, so that the incident light can be efficiently guided to the photoelectric conversion unit 202 by the inner lens 205 even when the incident angle is severe.

Next, the detailed shape of the inter-pixel light shielding wall 210 will be described with reference to FIG. FIG. 3(a) is a schematic diagram showing a cross section parallel to the xy plane taken along line AA' in FIG. 2, and FIG. It is a schematic diagram showing a cross section. In FIGS. 3A and 3B, dotted lines 301 indicate boundaries between adjacent pixels, and indicate cross-sectional shapes of inter-pixel light shielding walls 210 .

FIG. 3C is an enlarged schematic diagram of a region 302 surrounded by a circular dotted line in FIG. In the corner of the inter-pixel light shielding wall 210 shown in FIG. 3C, the width 304 of the part forming the side and the angle in the pixel diagonal direction (in this embodiment, the direction parallel to the straight line −x=y in the figure) The width 305 of the part is shown. At this time, the corner area of the top surface of the inter-pixel light shielding wall 210 is larger than the corner area of the bottom surface of the inter-pixel light shielding wall 210 . With such a configuration, it is possible to block stray light in the inter-pixel adjacent portions in the diagonal direction of the pixels. That is, in the present embodiment, the width in the pixel diagonal direction of the corner of the uppermost surface of the interpixel light shielding wall 210 is larger than the width of the corner of the lowermost surface of the interpixel light shielding wall 210 in the pixel diagonal direction. is configured as

Moreover, the shape of the inter-pixel light shielding wall 210 is not limited to the example shown in FIG. 3 as long as it has a characteristic corner. For example, it may have a cross-sectional shape as shown in FIG. In this case, the width 401 in the pixel diagonal direction at the corner is at least twice the width 402 at the side. Moreover, the cross-sectional shape as shown in FIG.4(b) may be sufficient. This example is also an example of the shape of the inter-pixel light shielding wall 210 having the same characteristics, but the portion forming the side is not a side with a constant width, but gradually changes. In this case, the width 404 can be considered as the width of the portion forming the side.

Furthermore, in the present embodiment, the cross-sectional shape in the pixel diagonal direction at the corner of the inter-pixel light shielding wall is not limited to the shape shown in FIG. For example, the example shown in FIG. 4C has a shape in which the area or width monotonically decreases from the top to the bottom of the inter-pixel light shielding wall 210, which is similar to FIG. 2, but is not limited to such a shape. . For example, as shown in FIG. 4(d), the width or area may be increased only at the upper portion of the inter-pixel light shielding wall 210. As shown in FIG. It may have a shape in which the width or area decreases non-linearly. In particular, in the case of the shape shown in FIG. 4(c) or FIG. 4(e), since there is no step in the cross-sectional shape in the vertical direction, the manufacturing process is simplified, the manufacturing accuracy is improved, and the cost is reduced. can be done.

Further, in the present embodiment, the width or area in the pixel diagonal direction of the corner of the top surface of the inter-pixel light shielding wall 210 may be larger than the width or area of the gap of the top microlens 209 . good. Even with such a configuration, it is possible to suppress stray light entering the pixels. Further, the width or area in the pixel diagonal direction of the corner of the interpixel light shielding wall 210 on the lowermost surface may be smaller than the width or area of the gap of the top microlens 209 . By doing so, it is possible to further improve the effect of suppressing stray light entering the pixel.

FIG. 5A is a perspective view schematically showing only the top microlens 209 and the inter-pixel light shielding wall 210. FIG. In many imaging pixels, there is a flat or nearly flat area at the corners of the top microlens in the pixel diagonal direction, and this area is called a gap 502 of the top microlens 501 .

FIG. 5(b) is a schematic view including some of the adjacent pixels as seen from the +z direction. In FIG. 5B, there is a gap 502 at the corner of the top microlens 501 in the pixel diagonal direction, and the width 503 of the gap in the pixel diagonal direction is shown. FIG. 5C is a diagram showing the relationship between the width 503 of the gap 502 of the top microlens 501 in the diagonal direction of the pixel and the width 504 at the top and the width 505 at the bottom of the inter-pixel light shielding wall 210 . In this embodiment, these width relationships are also characterized as area relationships. However, the size relationship of the widths 503, 504, 505 in FIG. 5(c) is not limited to these.

Next, a pupil division phase difference method focus detection method will be described. FIG. 6 is a schematic diagram showing the correspondence relationship between the imaging element and pupil division of this embodiment.
In FIG. 6, a line 604 indicates the position (plane) of the subject, and an image of the subject is formed at a position 606 on the surface of the image sensor through the imaging optical system at a position 605 . Further, a position 609 represents the rear side position of the inner lens of the image pickup pixel forming the image sensor. A secondary photoelectric conversion unit 602 and a secondary photoelectric conversion unit 603, which are divided in the x direction for each pixel of the image sensor, receive light beams passing through a pupil partial region 607 and a pupil partial region 608, respectively.

By selecting the signals of the sub-photoelectric conversion unit 602 and the sub-photoelectric conversion unit 603 for each pixel, a parallax image corresponding to a specific pupil partial area in the pupil partial areas 607 and 608 of the imaging optical system is generated. Obtainable. Specifically, by selecting a signal corresponding to the sub-photoelectric conversion unit 602 for each pixel, a parallax image having a resolution corresponding to the number of effective pixels corresponding to the pupil partial region 607 of the imaging optical system can be obtained. Further, by selecting the signal corresponding to the sub-photoelectric conversion unit 603, a parallax image having a resolution corresponding to the number of effective pixels corresponding to the pupil partial area 608 of the imaging optical system can be obtained.

Further, by adding all the signals of the secondary photoelectric conversion units 602 and 603 for each pixel, it is possible to generate a captured image with a resolution corresponding to the number of effective pixels. In this embodiment, as shown in FIG. 6, the position of the top microlens of an imaging pixel farther from the center of the imaging element is decentered toward the center of the imaging pixel. This is because the direction of the principal ray from the imaging optical system is more inclined in a portion far from the center of the image pickup device, and this is to accommodate this inclination.

Next, the relationship between the image shift amount of the parallax image and the defocus amount will be described. FIG. 7 is a diagram for explaining the outline of the relationship between the amount of image shift between parallax images and the amount of defocus. An image pickup device (not shown) of this embodiment is arranged at an image pickup device surface position 606, and the exit pupil of the imaging optical system is divided into a pupil partial region 607 and a pupil partial region 608, as in FIG. shall be

The defocus amount d represents the distance from the imaging position of the subject to the surface position of the imaging element (imaging plane) 606, and its magnitude is |d|. Here, with respect to the defocus amount d, a negative sign (d<0) indicates a front focus state in which the imaging position of the subject is on the side of the subject from the imaging plane, and the imaging position of the subject is on the opposite side of the imaging plane to the subject. We define the back pin state as positive sign (d>0). The in-focus state in which the imaging position of the object is on the imaging plane is d=0. In FIG. 7, an object 701 shows an example of an in-focus state (d=0), and an object 702 shows an example of a front focus state (d<0). Also, the front focus state (d<0) and the rear focus state (d>0) are combined to be a defocus state (|d|>0).

In the front focus state (d<0), of the light beams from the subject 702, the light beams that have passed through the partial pupil region 607 (608) are condensed once and then spread out around the barycentric position G1 (G2) of the light beams. It spreads to P1 (P2) and becomes a blurred image on the imaging plane 606 . The blurred image is received by the secondary photoelectric conversion unit 602 and the secondary photoelectric conversion unit 603 to generate a parallax image. Therefore, in the parallax image generated from the signals of the secondary photoelectric conversion units 602 and 603, the object 702 is recorded as a blurred object image with width P1 (P2) at the center of gravity position G1 (G2). The blur width P1 (P2) of the subject image increases approximately in proportion to the increase in the magnitude |d| of the defocus amount d. Similarly, the magnitude |p| of the image shift amount p (=G1−G2) of the subject image between the parallax images is also roughly proportional to the increase in the magnitude |d| of the defocus amount d. increasing. Even in the rear focus state (d>0), the direction of image shift of the object image between the parallax images is opposite to that in the front focus state, but the same is true. In the in-focus state (d=0), the positions of the centers of gravity of the object images between the parallax images match (p=0), and no image shift occurs.

Therefore, in the two (plural) parallax images obtained using the signals of the secondary photoelectric conversion unit 602 and the secondary photoelectric conversion unit 603, as the defocus amount of the parallax images increases, the number of parallax images increases. The magnitude of the image shift amount between the two increases. Focus detection using a focus detection signal of a split-pupil phase difference detection method is performed by calculating an image shift amount between parallax images by correlation calculation using a signal from the photoelectric conversion unit of the image sensor of the present embodiment. can be done.

In addition, in the example shown in FIG. 2, the imaging pixel is a back-illuminated imaging pixel that does not have a wiring layer for signal transmission between the photoelectric conversion unit 202 and the top microlens 209 . In front-illuminated imaging pixels, stray light that is scattered and absorbed in the wiring layer is difficult to eliminate in the wiring layer. For this reason, it is preferable to apply the present embodiment to a back-illuminated imaging pixel, and the effect of suppressing stray light can be improved. By adopting such a configuration, it is possible to realize an imaging device with higher accuracy in focus detection of the phase difference method by pupil division.

Next, a specific configuration example of an image pickup apparatus to which the above-described image pickup device is applied will be described. FIG. 8 is a block diagram showing a functional configuration example of a digital camera, which is an imaging apparatus according to this embodiment, and has an imaging device 106 . In this embodiment, a digital camera will be described as an example of an imaging device, but a mobile phone, a surveillance camera, a mobile camera, a medical camera, or the like may be used as an imaging device having the above-described imaging device. In the image pickup apparatus of this embodiment, the signal from the photoelectric conversion unit of the image pickup device 106 is used for focus adjustment of the pupil division phase difference method, and at the same time, it is also used as an image pickup signal.

The digital camera of this embodiment is a lens-interchangeable single-lens reflex camera, and has a lens unit 800 and a camera body 820 . The lens unit 800 is attached to the camera body 820 via a mount M indicated by a dotted line in the center of the drawing.

The lens unit 800 has an optical system (first lens group 801, diaphragm 802, second lens group 803, focus lens group (hereinafter simply referred to as "focus lens") 804) and a drive/control system. As described above, the lens unit 800 includes the focus lens 804 and corresponds to a photographing lens that forms an optical image of a subject.

The first lens group 801 is arranged at the tip of the lens unit 800 and held movably in the optical axis direction OA. The diaphragm 802 functions not only to adjust the amount of light during shooting, but also as a mechanical shutter that controls the exposure time during still image shooting. However, since the image sensor of this embodiment is provided with a global shutter mechanism, it is not always necessary to use a mechanical shutter using an aperture.

The diaphragm 802 and the second lens group 803 are integrally movable in the optical axis direction OA, and move together with the first lens group 801 to achieve a zoom function. The focus lens 804 is also movable in the optical axis direction OA, and the subject distance (focusing distance) at which the lens unit 800 focuses changes depending on the position. By controlling the position of the focus lens 804 in the optical axis direction OA, focus adjustment for adjusting the focal length of the lens unit 800 is performed.

The drive/control system has a zoom actuator 811 , an aperture actuator 812 , a focus actuator 813 , a zoom drive circuit 814 , an aperture drive circuit 815 and a focus drive circuit 816 . Furthermore, it has a lens MPU (MPU: microprocessor) 817 and a lens memory 818 .

A zoom drive circuit 814 drives the first lens group 801 and the third lens group 803 in the optical axis direction OA using a zoom actuator 811 to control the angle of view of the optical system of the lens unit 800 . A diaphragm driving circuit 815 drives the diaphragm 802 using the diaphragm actuator 812 and controls the aperture diameter and opening/closing operation of the diaphragm 802 . A focus drive circuit 816 uses a focus actuator 813 to drive the focus lens 804 in the optical axis direction OA to change the focal length of the optical system of the lens unit 800 . Also, the focus drive circuit 816 detects the current position of the focus lens 804 using the focus actuator 813 .

A lens MPU 817 performs all calculations and controls related to the lens unit 800 and controls a zoom drive circuit 814 , an aperture drive circuit 815 and a focus drive circuit 816 . Also, the lens MPU 817 is connected to the camera MPU 825 through the mount M to communicate commands and data. For example, the lens MPU 817 detects the position of the focus lens 804 and notifies lens position information in response to a request from the camera MPU 825 . This lens position information includes the position of the focus lens 804 in the optical axis direction OA, the position and diameter of the exit pupil in the optical axis direction OA when the optical system is not moved, and the optical axis of the lens frame that limits the luminous flux of the exit pupil. It contains information such as position and diameter in direction OA. The lens MPU 817 also controls a zoom drive circuit 814 , an aperture drive circuit 815 and a focus drive circuit 816 in response to requests from the camera MPU 825 . A lens memory 818 preliminarily stores optical information necessary for automatic focus detection. The camera MPU 825 controls operations of the lens unit 800 by executing programs stored in, for example, an internal non-volatile memory or lens memory 818 .

Camera body 820 has an optical system (optical low-pass filter 821 and imaging element 106) and a drive/control system. The first lens group 801, diaphragm 802, second lens group 803, and focus lens 804 of the lens unit 800 and the optical low-pass filter 821 of the camera body 820 constitute an imaging optical system.

The optical low-pass filter 821 reduces false colors and moiré in the captured image. The imaging device 106 is the imaging device described in this embodiment, and is basically composed of a microlens, an upper transparent electrode, a lower transparent electrode for pupil division, an organic photoelectric conversion film, an optical waveguide, a Si photoelectric conversion unit, and peripheral circuits. configured As described above, the image sensor 106 has 6000 pixels in the horizontal direction and 4000 pixels in the vertical direction. The image sensor 106 of this embodiment has a pupil division function in the photoelectric conversion unit, and is capable of phase difference AF (autofocus) using image data based on a signal from the photoelectric conversion unit. The image processing circuit 824 generates phase difference AF data and moving images from image data obtained from the photoelectric conversion unit 202 of the image sensor 106 . Furthermore, the image processing circuit 824 generates a still image, display, and recording image data from the image data obtained from the photoelectric conversion unit 202 .

The drive/control system has an image sensor drive circuit 823 , an image processing circuit 824 , a camera MPU 825 , a display section 826 , an operation switch group 827 , a memory 828 and an imaging plane phase difference detection section 829 . Note that the imaging apparatus of this embodiment may include a communication unit (not shown) connected to the camera MPU 825 . The communication unit is not limited to wired communication such as USB and LAN, and includes wireless communication such as wireless LAN. The imaging apparatus of this embodiment can acquire a control signal from an external device via the communication unit, and can distribute image data and the like based on the acquired control signal.

The imaging device drive circuit 823 controls the operation of the imaging device 106 , A/D-converts the acquired moving image and still image signals, and transmits them to the camera MPU 825 . The image processing circuit 824 performs general image processing such as gamma conversion, white balance adjustment processing, color interpolation processing, compression encoding processing, etc. performed by a digital camera on each image data acquired by the image sensor 106 . The image processing circuit 824 also generates a phase difference AF signal (focus detection data).

The camera MPU 825 performs all calculations and controls related to the camera main body 820, and controls the image sensor drive circuit 823, image processing circuit 824, display unit 826, operation switch group 827, memory 828, and imaging plane phase difference detection unit 829. . The camera MPU 825 is connected to the lens MPU 817 via the mount M and communicates commands and data with the lens MPU 817 . The camera MPU 825 requests the lens MPU 817 to acquire the lens position, to drive the aperture, focus lens, and zoom with a predetermined drive amount, and to acquire optical information specific to the lens unit 800 . The camera MPU 825 incorporates a ROM 825a storing programs for controlling camera operations, a RAM 825b storing variables, and an EEPROM 825c storing various parameters.

A display unit 826 is composed of an LCD (Liquid Crystal Display) or the like, and displays information regarding the photographing mode of the camera, a preview image before photographing, a confirmation image after photographing, an in-focus image at the time of focus detection, and the like. The operation switch group 827 includes a power switch, a release (shooting trigger) switch, a zoom operation switch, a shooting mode selection switch, and the like. A memory 828 is a detachable flash memory, and records captured image data.

The imaging plane phase difference detection unit 829 uses focus detection data from the photoelectric conversion unit 202 obtained by the image processing circuit 824 to perform focus detection processing by a phase difference detection method. Specifically, the image processing circuit 824 generates a pair of image data from the photoelectric conversion unit 202 formed by a light flux passing through a pair of pupil regions of the imaging optical system as focus detection data, and calculates the imaging plane phase difference. The detection unit 829 detects the amount of defocus based on the amount of deviation between the pair of image data. Thus, the imaging plane phase difference detection unit 829 of the present embodiment performs phase difference AF (imaging plane phase difference AF) based on the output of the imaging element 106 without using a dedicated AF sensor.

As described above, by applying the image pickup element having the image pickup pixels having the structure described above to an image pickup apparatus such as a digital camera, it is possible to provide an image pickup apparatus with high focus detection accuracy.

(Second embodiment)
A second embodiment of the present invention will be described below with reference to the drawings. Only points different from the first embodiment will be described below. The basic configuration of the imaging element is the same as that of FIG. 1, but the configuration of the imaging pixels is different from that of the first embodiment, and will be described below.

FIG. 9 is a schematic diagram showing a cross section parallel to the zx plane in the imaging pixel 102 in FIG. 1(a). An n-type silicon substrate 901 is provided with a photoelectric conversion section 902 formed by ion implantation from the surface side. The photoelectric conversion unit 902 is electrically separated into sub-photoelectric conversion units 902a and 902b by a central separation region 911, and the pixel regions corresponding to each are sub-pixels.

In addition, the silicon substrate 901 includes an insulating portion 904 made of silicon oxide (SiO _x ) on the surface side, a wiring layer made of a plurality of wirings 905 , and a light guide made of silicon nitride (SiN _x ) penetrating through the insulating portion 904 . A wave path 903 is formed. Here, the edge region 910 represents the edge region of the optical waveguide 903 on the side opposite to the silicon substrate 901 side (that is, on the microlens 909 side). A color filter 907 is formed above the optical waveguide 903 via a passivation film 906, and a microlens 909 is arranged above it.

Light incident from the outside of the imaging pixel 102 is introduced into the optical waveguide 903 while being condensed by the microlens 909 . Inside the optical waveguide 903 , the light propagates while being confined by total reflection (or partial reflection) on the side surface, and reaches the photoelectric conversion section 902 . At this time, since light is confined in the optical waveguide 903, it is possible to avoid light loss due to leakage of light to the insulating portion 904, scattering and absorption in the wiring 905, and the like.

Generally, in an imaging device, the microlens on each pixel is shifted toward the center as the distance from the center of the imaging surface increases concentrically. For example, a microlens at an image plane position approximately +10 millimeters in the x-direction from screen center is shifted a certain amount in the x-direction. FIG. 10 shows an example of an imaging pixel in which the microlens 1001 is shifted far from the center of the imaging plane.

However, in a pixel at an image plane position distant from the central position, a light ray indicated by an arrow 1002 in FIG. is not directly incident. The light that is directly incident on the optical waveguide is introduced into the photoelectric conversion section while basically maintaining the light collection distribution by the microlenses. On the other hand, the light that collides with the edge region 910 not only contributes to the loss itself, but rather enters the optical waveguide from the outside of the side surface of the optical waveguide. It becomes a cause of disturbing the distribution of the internal electromagnetic field. In phase-difference focus detection based on pupil division in which the photoelectric conversion unit is divided, this disturbance in the electromagnetic field distribution affects focus detection accuracy.

Therefore, in the present embodiment, as shown in FIG. 11, a light shielding film made of tungsten (W) having a thickness of about 30 nm is placed closer to the microlens 909 than the edge region 910 of the optical waveguide 903 of the imaging pixel 102 of FIG. A portion 1101 is provided. Note that the material of the light shielding portion 1101 is not limited to tungsten as long as it is a material that has a property of blocking incident light by absorbing, scattering, or reflecting it. As a result, light incident from the direction indicated by arrow 1002 in FIG. 10 is reflected, absorbed, and effectively scattered by the light shielding portion 1101, thereby avoiding or suppressing the disturbance of the electromagnetic field distribution inside the optical waveguide 903. becomes possible. That is, it is possible to suppress deterioration in the focus detection accuracy of the phase difference method due to pupil division. A distance 1102 between the edge region 910 of the optical waveguide 903 and the light shielding portion 1101 is preferably smaller than the center wavelength or peak wavelength of the wavelength band of light handled in the pixel. As a result, it is possible to suppress the light leaking to the adjacent pixels through the space between the edge region 910 and the light shielding portion 1101 .

FIGS. 12(a) and 12(b) are cross-sections of a pixel having an optical waveguide at a position on the image plane away from the central position, and the shading represents the Poynting vector magnitude distribution. . This distribution shows a steady state when a plane wave with a wavelength of 550 nm is incident from above the microlens in the zx plane at an angle of 3 degrees with respect to the z-axis toward the center of the image plane. In both FIGS. 12(a) and 12(b), the gray scale of black and white representing the strength of the Poynting vector is the same. The photoelectric conversion unit of the imaging pixel in FIG. 12A is electrically divided into secondary photoelectric conversion units 1204a and 1204b. Similarly, the photoelectric conversion unit of the imaging pixel in FIG. 12B is electrically divided into secondary photoelectric conversion units 1205a and 1205b.

No light shielding part is provided near the edge region of the optical waveguide in FIG. A light shielding portion 1203 is provided. In the example shown in FIG. 12(a), the incident light is scattered in the region of the edge, and the light entering from the side surface of the optical waveguide disturbs the electromagnetic field distribution inside the optical waveguide. As a result, as shown in the region 1201, most of the light that should be incident mainly on the secondary photoelectric conversion unit 1204b is incident on the secondary photoelectric conversion unit 1204a on the opposite side.

On the other hand, in the example shown in FIG. 12(b), no significant disturbance of the electromagnetic field distribution is observed inside the optical waveguide, and as can be seen from the region 1202, a large amount of light is incident on the secondary photoelectric conversion portion 1205b, which is supposed to enter. It can be seen that By adopting a configuration in which a light shielding portion is provided as shown in FIG. 12B, it is possible to suppress deterioration in pupil division performance and improve focus detection accuracy. Note that the focus detection method in the phase difference method of pupil division is the same as that described in the first embodiment.

As described above, according to the present embodiment, since the light blocking portion 1101 is provided at a position closer to the microlens 909 than the edge region 910 of the optical waveguide 903, focus detection accuracy can be improved. By applying the image pickup device according to the present embodiment to an image pickup apparatus such as a digital camera, it is possible to provide an image pickup apparatus with high focus detection accuracy. Details of the imaging device are the same as in the first embodiment.

(Third embodiment)
A third embodiment of the present invention will be described below with reference to the drawings. Only points different from the second embodiment will be described below. The basic configuration of the imaging device is the same as that of FIG. 1, but the configuration of the imaging pixels is different from that of the second embodiment, and will be described below.

FIG. 13 is a schematic diagram showing a cross section parallel to the zx plane in the imaging pixel 102 in FIG. 1A in this embodiment. Only differences from FIG. 9 will be described below. The silicon substrate 901 has an insulating portion 1301 made of silicon oxide (SiO _x ) on the upper surface thereof, a wiring layer made of a plurality of wirings 905 , and an optical waveguide made of silicon nitride (SiN _x ) embedded in the insulating portion 1301 . 1302 is formed. In this embodiment, the edge region does not exist on the side opposite to the silicon substrate 901 side in the optical waveguide 1302 . Therefore, the insulating portion 1301 on the side of the optical waveguide 1302 is arranged continuously above the optical waveguide 1302 .

As described above, in the pixel configuration of this embodiment, the optical waveguide 1302 is embedded in the insulating portion 1301, and the edge region 910 as shown in FIG. 9 does not exist. Therefore, there is no need to consider adverse effects such as scattering and reflection at the edges, and a decrease in focus detection accuracy can be avoided.

(Fourth embodiment)
A fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 15 is a diagram for explaining an outline of the arrangement of imaging pixels and focus detection pixels of the imaging element in this embodiment. In FIG. 15, the pixel (imaging pixel) array of a two-dimensional CMOS sensor (imaging device) is shown in a range of 4 columns×4 rows, and the array of focus detection pixels is shown in a range of 8 columns×4 rows.

A pixel group 1500 of 2 columns×2 rows is shown in the upper left position of FIG. In the pixel group 1500, an imaging pixel 1500R having R (red) spectral sensitivity is located at the upper left, imaging pixels 1500G having G (green) spectral sensitivity are located at the upper right and lower left, and imaging pixels having B (blue) spectral sensitivity are located. Pixel 1500B is located at the bottom right. Further, each pixel is composed of a first focus detection pixel (sub-pixel) 1501 and a second focus detection pixel (sub-pixel) 1502 arranged in 2 columns×1 row.

Note that although a large number of pixel groups 1500 are arranged on the imaging surface of the imaging device, in order to simplify the explanation, FIG. detection pixels) are arranged. A large number of these arrays enable acquisition of captured images and focus detection signals. In this embodiment, the pixel period P is 1.0 μm, the number of pixels N is 5575 horizontal columns×3725 vertical rows=approximately 20.75 million pixels, the column direction period P _AF of the focus detection pixels is 0.5 μm, and the number of focus detection pixels N Description will be made assuming that _{the AF} is an imaging device with 11,150 horizontal columns×3,725 vertical rows=approximately 41,530,000 pixels.

FIG. 16A shows a plan view of one imaging pixel 1500G of the imaging element shown in FIG. A cross-sectional view seen from the -y side is shown in FIG. In the example shown in FIG. 16, the imaging pixel 1500G having a spectral sensitivity of G (green) is taken as an example, but the imaging pixel 1500R having a spectral sensitivity of R (red) and the spectral sensitivity of B (blue) are used. It is assumed that the imaging pixel 1500B also has a similar configuration.

As shown in FIG. 16B, the imaging pixel according to this embodiment includes a photoelectric conversion unit 1601 including secondary photoelectric conversion units 1601a and 1601b near the surface of the silicon substrate. In addition, the imaging pixel according to this embodiment includes a top microlens 1605 for condensing light incident from the imaging optical system and introducing the light into the imaging pixel. Between the top microlens 1605 and the photoelectric conversion section 1601, an insulating section 1600 made of silicon oxide (SiO _x ), a wiring layer made up of a plurality of wirings 1613, and a light guide for efficiently guiding light to the photoelectric conversion section 1601 are provided. A wave path 1610 is provided. An inner lens 1606 may be provided depending on the pixel design. With this pixel structure, light incident on the image pickup pixel is collected by the top microlens 1605 , dispersed by a color filter (not shown), and propagated through the optical waveguide 1610 .

16(c) to 16(e) are diagrams for explaining how the light incident on the pixel propagates within the pixel. FIGS. 16(c) to 16(e) show the results of calculation by the FDTD method (Finite Difference Time Domain Method) of the propagation state of a plane wave incident at a specific angle. Here, the focal position 1607 of the top microlens 1605 is also shown. A range from the focal position 1607 to the position 1608a and a range from the focal position 1607 to the position 1608b respectively indicate the one-side focal depth range of the top microlens 1605. FIG.

As shown in FIG. 16D, when light is incident at an angle of 0° to the optical axis (parallel to the z-direction), the amounts of light received by the two secondary photoelectric conversion units 1601a and 1601b are almost the same. Become. On the other hand, as shown in FIG. 16(c), when the light is incident at −15° with respect to the optical axis, the amount of light received by the secondary photoelectric conversion unit 1601b increases. On the other hand, as shown in FIG. 3E, when light is incident at an angle of 15° to the optical axis, the amount of light received by the sub-photoelectric converter 1601a increases. In the secondary photoelectric conversion units 1601a and 1601b, pairs of electrons and holes are generated according to the amount of light received, and after separation in the depletion layer, negatively charged electrons are accumulated in the n-type layer (not shown). On the other hand, holes are discharged to the outside of the imaging device through the p-type layer connected to a constant voltage source (not shown).

FIG. 17 is a diagram for explaining the outline of the correspondence relationship between the pixel structure and pupil division shown in FIG. The lower part of FIG. 17 shows a cross section of the pixel structure shown in FIG. 16(a) taken along line aa from the +y side, and the upper part of FIG. 17 shows the exit pupil plane of the imaging optical system. In FIG. 17, the x-axis and y-axis of the sectional view are reversed with respect to FIG. 16 in order to correspond to the coordinate axes of the exit pupil plane.

In FIG. 17, the first pupil partial region 1701 and the light-receiving surface of the sub-photoelectric conversion unit 1601a whose center of gravity is decentered in the -X direction are in a substantially conjugate relationship due to the top microlens 1605. represents the pupil region where light can be received. The center of gravity of the first pupil partial region 1701 is decentered on the +X side on the pupil plane.

On the other hand, the second pupil partial region 1702 has a substantially conjugate relationship with the light receiving surface of the photoelectric conversion unit 1601b whose center of gravity is decentered in the +X direction by the top microlens 1605, and can be received by the second focus detection pixel 1502. It represents the pupil area. The center of gravity of the second pupil partial region 1702 is decentered on the -X side on the pupil plane. Also, in FIG. 17, a pupil region 1700 is a pupil region where light can be received by the entire imaging pixel 1500G when the two sub-photoelectric conversion units 1601a and 1601b are combined. Note that the focus detection method by the phase difference method by pupil division is the same as the method described in the first embodiment.

The luminous flux that has passed through different pupil partial areas of the first pupil partial area 1701 and the second pupil partial area 1702 is incident on each pixel of the imaging pixel at a different angle, and the first focus detection pixel 1501 divided into two and the second focus detection pixel 1502 . In the imaging pixel of this embodiment, the first focus detection pixel 1501 receives a light flux passing through the first pupil partial area 1701 of the imaging optical system, and the second focus detection pixel 1502 receives the light flux passing through the second pupil partial area 1702. Receiving light flux. In other words, in the image sensor according to this embodiment, a plurality of imaging pixels are arranged to receive light beams passing through a pupil region 1700 including all of the first partial pupil region 1701 to the second partial pupil region 1702 .

Note that, if necessary, the imaging pixels, the first focus detection pixels, and the second focus detection pixels may be configured individually, and the first focus detection pixels and the second focus detection pixels may be included in part of the imaging pixel array. may be partially arranged. In this embodiment, the first focus detection pixel 1501 of each image pickup pixel of the image sensor is generated as the first focus signal, the second focus detection pixel 1502 of each image sensor of the image sensor is generated as the second focus signal, and the focus signal is generated. detect. Also, by adding the first focus detection pixel 1501 and the second focus detection pixel 1502 in each pixel of the imaging pixels, an imaging signal (captured image) having a resolution corresponding to the number of effective pixels is generated.

Next, the refractive index of each pixel of RGB will be described. FIG. 18 is a diagram for explaining the top microlens 1605 arranged in the imaging pixel and the beam waist radius of the light condensed by the top microlens 1605 . In FIG. 18, a luminous flux 1801 is a luminous flux guided from the top microlens 1605 . where α is the aperture angle of the top microlens 1605, f is the focal length of the top microlens 1605, D is the diameter of the top microlens 1605, and n is the effective refractive index between the top microlens 1605 and the photoelectric conversion unit 1601. ', and let the wavelength of light be λ. In this case, the beam waist radius (minimum spot radius of light) w when the light of wavelength λ is condensed by the top microlens 1605 is expressed by the following formula (1) using Rayleigh's formula for resolution (at the diffraction limit): defined by
w=1.22×fλ/n′D (1)

Since a number of layers are stacked in an actual pixel structure, the refractive index between the top microlens and the photoelectric conversion section is not set to a fixed value. However, in an imaging pixel having a large proportion of the optical waveguide as in this embodiment, when the refractive index between the top microlens and the photoelectric conversion portion is considered as the effective refractive index n′, the influence of the refractive index n of the optical waveguide is is large. Therefore, the effective refractive index n' in Equation (1) largely depends on the refractive index n in the optical waveguide. Therefore, it can be seen from equation (1) that the minimum spot radius w of the light condensed by the top microlens 1605 is in principle proportional to the wavelength λ and inversely proportional to the refractive index n.

In the image pickup device of this embodiment, the size of the image pickup pixel is 1.0 μm, and the size of the sub-pixel when pupil division is performed is simply 0.5 μm. Since the imaging element of the pixel group as shown in FIG. 15 is composed of pixels that receive light corresponding to the wavelength bands of R (red), G (green), and B (blue), pixels corresponding to each color The wavelengths of light propagating within are different. That is, the wavelength becomes shorter in the order of red, green, and blue.

When the refractive index inside the optical waveguide is the same, the shorter the wavelength λ, the smaller the minimum spot radius w of light, and the longer the wavelength λ, the larger the minimum spot radius w of light, according to equation (1). For example, when the refractive index n inside the optical waveguide is the refractive index of SiO ₂ (approximately 1.46), it is difficult for red imaging pixels to introduce light into the divided sub-photoelectric conversion portions. The optical waveguide may be divided so as to correspond to the two sub-photoelectric conversion portions, but even in this case, it is difficult to introduce light into the divided optical waveguides, and the longer the wavelength of the light, the less light is received. .

In order to solve this situation, the imaging pixels in the imaging element of the present embodiment are configured so that the refractive index inside the optical waveguide is the highest in the R pixels. When the refractive indices inside the optical waveguides of the R, G, and B pixels are nR, nG, and nB, respectively, the relationship is such that nR>nG>nB. As a result, even light with a long wavelength can be introduced into the narrow auxiliary photoelectric conversion section or optical waveguide.

Also, as one method of avoiding the deterioration of the pupil division performance of the R pixel, a method of sufficiently increasing the refractive index n of the optical waveguide of the entire image sensor is conceivable. However, in this method, as pixels are made smaller, separation performance between pixels is degraded, and a problem arises in that crosstalk between pixels increases. Therefore, by configuring the refractive index inside the optical waveguide so as to satisfy the relationship nR>nG>nB, optical crosstalk between pixels can be reduced.

FIG. 19 is a diagram for explaining directions in which crosstalk occurs among R, G, and B pixels. FIG. 19A shows a case where the refractive indices in the optical waveguides of R, G and B pixels are all the same refractive index n. Further, FIG. 19B shows a relationship of nR>nG>nB where nR is the refractive index of the R pixel, nG is the refractive index of the G pixel, and nR is the refractive index of the R pixel. It shows the case where .

If the refractive index of the optical waveguide is changed according to the length of the wavelengths of R, G, and B, it becomes difficult to guide unnecessary light beams that cause crosstalk between pixels into the optical waveguide. Become. A specific description will be given using the R pixel and the G pixel in FIG. 19(b).

If the optical waveguides have the same refractive index, the minimum spot radius of the light flux incident on the R pixel is larger than the minimum spot radius of the light flux incident on the G pixel. Therefore, by appropriately setting the refractive index nR of the R pixel and the refractive index nG of the G pixel, it is possible to prevent the luminous flux incident on the R pixel from crosstalking with the G pixel. Thus, crosstalk from G pixels to R pixels cannot be reduced, but crosstalk from R pixels to G pixels can be reduced. The same is true between the G pixel and the B pixel, and crosstalk from the G pixel to the B pixel can be reduced by appropriately setting the refractive index nB of the B pixel.

As described above, according to the present embodiment, it is possible to suppress crosstalk between pixels while avoiding deterioration in pupil division performance of R pixels having a long wavelength. In the present embodiment, G pixels are described as one type of pixel. However, G pixels horizontally adjacent to R pixels may be distinguished as Gr pixels, and G pixels horizontally adjacent to B pixels may be distinguished as Gb pixels. good. Considering optical leakage from adjacent pixels, Gr pixels and Gb pixels may have different spectral sensitivities. Therefore, the refractive index of the optical waveguide may be made different between the Gr pixel and the Gb pixel.

Also, if the minimum spot radius of the red image pickup pixel is reduced, light can be introduced into the narrow sub-photoelectric conversion section or optical waveguide. Therefore, the refractive index of the optical waveguide of the imaging pixel for red may be made larger than that of the other colors, and the refractive indexes of the optical waveguides of the imaging pixels of green and blue may be the same.

Next, an example of an imaging device using the imaging device according to this embodiment will be described with reference to FIG. FIG. 14 is a block diagram showing a functional configuration example of a digital camera, which is an image pickup apparatus according to this embodiment, and has the above-described image pickup device. In this embodiment, a digital camera will be described as an example of an imaging device, but a mobile phone, a surveillance camera, a mobile camera, a medical camera, or the like may be used as an imaging device having the above-described imaging device. In the image pickup apparatus of this embodiment, the signal from the photoelectric conversion unit of the image pickup device is used for the focus adjustment of the pupil division phase difference method, and at the same time, it is also used as the image pickup signal.

In FIG. 14, the first lens group 1401 arranged at the tip of the imaging optical system is held so as to be able to move back and forth along the optical axis. The diaphragm/shutter 1402 adjusts the aperture diameter to adjust the amount of light during photography, and also functions as a shutter for adjusting the exposure time during still image photography. The aperture/shutter 1402 and the second lens group 1403 move forward and backward together in the optical axis direction.

The third lens group 1405 adjusts the focus by advancing and retreating in the optical axis direction. An optical low-pass filter 1406 is an optical element for reducing false colors and moiré in a captured image. The imaging element 1407 is composed of a two-dimensional CMOS photosensor and peripheral circuits, and is arranged on the imaging plane of the imaging optical system. In addition, in this embodiment, as described above, an image pickup element having image pickup pixels having different refractive indices depending on colors is used.

A zoom actuator 1411 rotates a cam cylinder (not shown) to move the first lens group 1401 to the third lens group 1405 back and forth in the optical axis direction, thereby performing a zooming operation. A diaphragm/shutter actuator 1412 controls the aperture diameter of the diaphragm/shutter 1402 to adjust the amount of photographing light, and controls the exposure time during still image photographing. A focus actuator 1414 moves the third lens group 1405 back and forth along the optical axis to adjust the focus.

The illumination device 1415 is, for example, an electronic flash for illuminating an object during photographing, and is preferably a flash illumination device using a xenon tube, but may be an illumination device equipped with an LED that continuously emits light. The AF auxiliary light unit 1416 projects an image of a mask having a predetermined aperture pattern onto the field of view via a projection lens to improve focus detection capability for dark or low-contrast subjects.

The control unit 1421 includes a CPU that controls various aspects of the imaging apparatus main body, and further includes a calculation unit, ROM, RAM, A/D converter, D/A converter, communication interface circuit, and the like. The control unit 1421 drives various circuits of the imaging apparatus based on a predetermined program stored in the ROM, and executes a series of operations such as AF, photography, image processing, and recording processing.

The electronic flash control circuit 1422 controls lighting of the illumination device 1415 in synchronization with the shooting operation. The auxiliary light driving circuit 1423 controls lighting of the AF auxiliary light unit 1416 in synchronization with the focus detection operation. The imaging pixel drive circuit 1424 controls the imaging operation of the imaging device 1407 , A/D-converts the obtained image signal, and transmits the converted signal to the control unit 1421 . An image processing circuit 1425 performs processing such as gamma conversion, color interpolation, and JPEG compression of the image acquired by the image sensor 1407 .

A focus drive circuit 1426 drives and controls a focus actuator 1414 based on the result of focus detection, and drives the third lens group 1405 forward and backward in the optical axis direction for focus adjustment. An aperture shutter drive circuit 1428 drives and controls an aperture shutter actuator 1412 to control the opening of the aperture/shutter 1402 . A zoom driving circuit 1429 drives a zoom actuator 1411 according to the zoom operation of the photographer.

A display unit 1431 is a display device such as an LCD, and displays information about the shooting mode of the camera, a preview image before shooting, a confirmation image after shooting, a focus state display image at the time of focus detection, and the like. An operation switch group 1432 includes a power switch, a release (shooting trigger) switch, a zoom operation switch, a shooting mode selection switch, and the like. A flash memory 1433 is a detachable memory and records captured images.

As described above, by using the imaging device of this embodiment and applying it to the imaging device shown in FIG. 14, even if the imaging pixels are small, light can be efficiently introduced into the optical waveguide and the photoelectric conversion unit. .

202 photoelectric conversion unit 209 top microlens 210 light shielding wall between pixels

Claims (8)

An imaging element in which a plurality of imaging pixels are arranged two-dimensionally,
Each of the plurality of imaging pixels is
a plurality of electrically divided photoelectric conversion units;
microlens and
A light shielding wall surrounding the imaging pixel is provided between the photoelectric conversion unit and the microlens,
The width of the surface of the light shielding wall on the microlens side is larger than the width of the surface of the light shielding wall on the photoelectric conversion unit side, and
An imaging device according to claim 1, wherein an area of a corner portion of a surface of the light shielding wall on the photoelectric conversion unit side is smaller than an area of a gap of the microlens. 2. The imaging device according to claim 1, wherein the area of the corner portion of the surface of the light shielding wall on the microlens side is larger than the area of the gap of the microlens. A width of a corner portion of the light shielding wall in a pixel diagonal direction on the surface of the light shielding wall facing the microlens is larger than a width of the corner portion of the surface of the light shielding wall facing the photoelectric conversion unit in a pixel diagonal direction. The imaging device according to claim 1 or 2 . An imaging element in which a plurality of imaging pixels are arranged two-dimensionally,
Each of the plurality of imaging pixels is
a plurality of electrically divided photoelectric conversion units;
microlens and
A light shielding wall surrounding the imaging pixel is provided between the photoelectric conversion unit and the microlens,
The width of the surface of the light shielding wall on the microlens side is larger than the width of the surface of the light shielding wall on the photoelectric conversion unit side, and
An imaging device according to claim 1, wherein a width of a corner portion of the light shielding wall on the photoelectric conversion unit side in a pixel diagonal direction is smaller than a width of a gap of the microlens in the pixel diagonal direction. 5. The light shielding wall according to any one of claims 1 to 4 , wherein the width of the corner portion of the light shielding wall in the pixel diagonal direction is at least twice as large as the width of the side portion of the light shielding wall. image sensor. 6. The structure according to any one of claims 1 to 5 , wherein each of the plurality of image pickup pixels has a structure in which there is no wiring layer for signal transmission between the photoelectric conversion unit and the microlens. image sensor. An imaging device having an imaging element,
The imaging element is
An imaging element in which a plurality of imaging pixels are arranged two-dimensionally,
Each of the plurality of imaging pixels is
a plurality of electrically divided photoelectric conversion units;
microlens and
A light shielding wall surrounding the imaging pixel is provided between the photoelectric conversion unit and the microlens,
The width of the surface of the light shielding wall on the microlens side is larger than the width of the surface of the light shielding wall on the photoelectric conversion unit side, and
An imaging device according to claim 1, wherein an area of a corner portion of a surface of the light shielding wall on the photoelectric conversion unit side is smaller than an area of a gap of the microlens. An imaging device having an imaging element,
The imaging element is
An imaging element in which a plurality of imaging pixels are arranged two-dimensionally,
Each of the plurality of imaging pixels is
a plurality of electrically divided photoelectric conversion units;
microlens and
A light shielding wall surrounding the imaging pixel is provided between the photoelectric conversion unit and the microlens,
The width of the surface of the light shielding wall on the microlens side is larger than the width of the surface of the light shielding wall on the photoelectric conversion unit side, and
The imaging device according to claim 1, wherein a width of a corner portion of the light shielding wall on the photoelectric conversion unit side in a pixel diagonal direction is smaller than a width of the gap of the microlens in the pixel diagonal direction.

Images