JP2009026941A - Imaging element and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging element and an imaging apparatus, capable of restraining the occurrence of color moire and luminance moire. <P>SOLUTION: The imaging element has a plurality of photoelectric conversion sections arranged in the direction of a first straight line and in the direction of a second straight line orthogonally crossing the direction of the first straight line on a semiconductor substrate. A light reception region at the photoelectric conversion sections is provided at a position deviating in the direction of the second straight line to the light reception region adjacent at least in the direction of the first straight line, or at a position deviating in the direction of the first straight line to the light reception region adjacent in the direction of the second straight line. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging element and an imaging apparatus that can suppress the occurrence of color moire and luminance moire.

  An imaging device such as a digital camera uses a CCD type or CMOS type imaging device. In particular, a so-called single-plate (single sensor) color image pickup device that can pick up a color image with one image pickup device is widely used. An image pickup device used in such an image pickup apparatus has three colors of RGB (or four colors obtained by adding one color other than RGB) regularly arranged on the surface of a light receiving region based on a predetermined pattern. Yes. By doing so, incident light is dispersed according to the color filter corresponding to each pixel by the image sensor, and a color image is generated in the light receiving unit of the pixel, thereby forming a color image by the imaging device. . As an arrangement of color filters, for example, there is a Bayer arrangement in which RGB colors are regularly arranged in a grid pattern. The following patent document is known as an image sensor provided with a color filter.

JP 2000-308070 A JP 2000-308080 A

  By the way, an image sensor including a color filter having a pattern in which RGB filters are regularly arranged, such as a Bayer array, outputs a color that originally does not exist in a subject when a subject with a fine pattern is imaged. Moire (also referred to as false color) or luminance moire that causes uneven luminance in a striped pattern occurs. Such color moiré and luminance moiré cannot be removed even by electrical filter processing, and therefore improvement has been desired to improve image quality.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an imaging element and an imaging apparatus capable of suppressing the occurrence of color moire and luminance moire.

The above object of the present invention is achieved by the following configurations.
(1) An imaging device in which a surface of a semiconductor substrate is provided with a plurality of photoelectric conversion units arranged in a first linear direction and a second linear direction orthogonal to the first linear direction,
The light receiving area in the photoelectric conversion unit is at least shifted in the second linear direction with respect to the light receiving area adjacent in the first linear direction, and in the light receiving area adjacent in the second linear direction. On the other hand, the imaging device is provided at one of the positions shifted in the first linear direction.
(2) The light incident surface of the photoelectric conversion unit is covered with a light-shielding film having an opening on each of the photoelectric conversion units, and the center of gravity of the opening is at least in the first linear direction. A position shifted in the second linear direction with respect to the center of gravity of the adjacent opening and a position shifted in the first linear direction with respect to the center of gravity of the opening adjacent to the second linear direction. The image pickup device according to (1), which is provided in any one of the above.
(3) Each of the plurality of photoelectric conversion units is at least shifted in the second linear direction with respect to the photoelectric conversion units adjacent in the first linear direction, and in the second linear direction. The image pickup device according to (1), wherein the image pickup device is provided at any one of positions shifted in the first linear direction with respect to the adjacent photoelectric conversion units.
(4) The image pickup device according to any one of (1) to (3), wherein a color filter is provided on a surface on the light incident side of the photoelectric conversion unit.
(5) An imaging device that forms an image by generating signal charges by photoelectrically converting incident light for each of a plurality of pixels provided in an imaging region of an imaging element,
The image sensor is
A plurality of photoelectric conversion units arranged on the surface of the semiconductor substrate in a first linear direction and a second linear direction orthogonal to the first linear direction;
The position of the light receiving region in the photoelectric conversion unit is shifted at least in the second linear direction with respect to the light receiving region adjacent in the first linear direction, and the light receiving adjacent in the second linear direction. An imaging apparatus, wherein the imaging apparatus is provided at any one of positions shifted in the first linear direction with respect to a region.
(6) The upper part of the photoelectric conversion unit is covered with a light-shielding film having an opening on each upper part of the photoelectric conversion unit, and the center of gravity of the opening is at least adjacent to the first linear direction. With respect to the second linear direction and a position shifted in the first linear direction with respect to the center of gravity of the opening adjacent to the second linear direction. The imaging apparatus according to (5), characterized in that:
(7) The position where the plurality of photoelectric conversion units are at least shifted in the second linear direction with respect to the photoelectric conversion units adjacent in the first linear direction, and adjacent to the second linear direction The imaging apparatus according to (5), wherein the imaging apparatus is provided at any one of positions shifted in the first linear direction with respect to the photoelectric conversion unit.
(8) The imaging according to any one of (5) to (7), further including a storage unit that stores position information indicating a shift amount of the light receiving area of each of the plurality of pixels. apparatus.
(9) The position information is coordinate information indicating a shift amount with respect to a first linear direction provided in the imaging region and a second linear direction orthogonal to the first linear direction. The imaging device according to (8).
(10) The imaging apparatus according to (8), wherein the storage unit is a mask ROM.
(11) The imaging apparatus according to (8), wherein the storage unit is an EEPROM.
(12) The imaging device according to any one of (5) to (11), wherein the imaging element is provided with a color filter on a surface irradiated with the incident light in the imaging region. .
(13) An imaging device in which a surface of a semiconductor substrate is provided with a first linear direction and a plurality of photoelectric conversion units arranged in a second linear direction orthogonal to the first linear direction,
The shift vector indicating the position of the center of gravity of the light receiving region with respect to the center of gravity of the photoelectric conversion unit is at least a shift vector of the light receiving region adjacent to the first linear direction and a shift of the light receiving region adjacent to the second linear direction An imaging device characterized by being different from any of the vectors

  According to the present invention, the light receiving area of each pixel in the imaging area is at least shifted in the second linear direction with respect to the light receiving area adjacent in the first linear direction, and in the second linear direction. It is provided at one of the positions shifted in the first linear direction with respect to the adjacent light receiving region. At this time, the entire arrangement of the pixels is arranged in a non-linear manner with respect to the first linear direction or the second linear direction, or 2 defined by the first linear direction and the second linear direction. The configuration is irregularly arranged on the dimension. It is possible to suppress the occurrence of color moire and luminance moire that can be seen when pixels are regularly arranged.

  In addition, it is preferable that the imaging apparatus includes a storage unit that stores position information indicating the shift amount of the light receiving area of each of the plurality of pixels. When a microlens is formed on the surface of the image sensor that is irradiated with incident light, it is difficult to arrange the microlens at a position that is shifted in accordance with the shift amount of the light receiving region. Therefore, the image can be corrected by performing a numerical calculation based on the positional information indicating the deviation amount, based on random variations in sensor sensitivity caused by regularly arranging the microlenses.

  ADVANTAGE OF THE INVENTION According to this invention, the image pick-up element and imaging device which can suppress generation | occurrence | production of a color moire and a luminance moire can be provided.

Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of an image pickup apparatus including an image pickup device according to the present invention. In this embodiment, a digital still camera will be described as an example. However, the present invention can also be applied to other types of digital cameras such as a camera mounted on a small electronic device such as a digital video camera or a mobile phone.

  The digital still camera shown in FIG. 1 includes a photographic lens 10, a CCD type image sensor 11, a diaphragm 12 provided between the two, an infrared cut filter 13, and an optical low-pass filter 14. The CPU 15 that controls the entire digital still camera controls the light emitting unit 16 and the light receiving unit 17 for flash, controls the lens driving unit 18 to adjust the position of the photographing lens 10 to the focus position, and the diaphragm driving unit 19. Then, the aperture amount of the diaphragm is controlled to adjust the exposure amount to be an appropriate exposure amount.

  In this embodiment, the imaging device 11 includes an R pixel that detects a signal corresponding to a red (R) incident light amount, a G pixel that detects a signal corresponding to a green (G) incident light amount, and blue (B). B pixels for detecting a signal corresponding to the amount of incident light are provided. Further, a luminance detection pixel that detects the luminance detection signal (W) may be provided. Note that the image sensor 11 may be other types such as a CMOS type instead of the CCD type.

  Further, the CPU 15 drives the image sensor 11 through the image sensor driving unit 20 as described in detail later, and outputs a subject image captured through the photographing lens 10. A user instruction signal is input to the CPU 15 through the operation unit 21, and the CPU 15 performs various controls according to the instruction.

  The operation unit 21 includes a shutter button, and focus adjustment is performed when the shutter button is in a half-pressed state (switch S1), and imaging is performed when the shutter button is in a fully-pressed state (switch S2).

  The electric control system of the digital still camera converts an analog signal processing unit 22 connected to the output of the image sensor 11 and R, G, and B color signals output from the analog signal processing unit 22 into digital signals. And an A / D conversion circuit 23, which are controlled by the CPU 15.

  Further, the electric control system of the digital still camera includes a memory control unit 25 connected to a main memory (frame memory) 24, a digital signal processing unit 26 that performs signal processing, and compresses or compresses a captured image into a JPEG image. A compression / expansion processing unit 27 that expands an image, an integration unit 28 that integrates photometric data to adjust the gain of white balance, an external memory control unit 30 to which a detachable recording medium 29 is connected, and the back of the camera And a display control unit 32 to which a liquid crystal display unit 31 mounted on the device is connected. These are connected to each other by a control bus 33 and a data bus 34 and controlled by a command from the CPU 15.

  In addition, a storage unit 35 is connected to the CPU. The storage unit 35 functions as storage means for storing in advance position information of a pixel array of an image sensor, which will be described later. As the storage unit 35, for example, a mask ROM or an EEPROM (Electronically Erasable and Programmable Read Only Memory) can be used.

  FIG. 2 is a plan view schematically showing the pixel arrangement in the imaging region of the imaging device 11. FIG. 3 is a cross-sectional view of the pixel array of FIG. 2 as viewed in the direction of arrow AA.

  The imaging element 11 has a semiconductor substrate 41 such as silicon, and a plurality of impurity diffusion layers are formed on the surface of the semiconductor substrate 41 on the side irradiated with incident light by ion implantation or the like. Specifically, on the surface of the semiconductor substrate 41, a positive charge accumulation region 43a composed of a high-concentration p-type impurity diffusion layer and an electron accumulation composed of an n-type impurity diffusion layer under the positive charge accumulation region 43a. Region 43b is formed. The positive charge accumulation region 43a and the electron accumulation region 43b function as a photoelectric conversion unit that generates signal charges by photoelectrically converting the received incident light.

  On the surface of the semiconductor substrate 41, a charge transfer region 42a made of a high-concentration n-type impurity diffusion layer is provided with a gap (right side in FIG. 3) from the positive charge storage region 43a and the electron storage region 43b, and the charge transfer A high-concentration p-type impurity diffusion layer 42b is formed below the region 42a. The charge transfer region 42a reads out the signal charge generated in the electron accumulation region 43b of the pixel located on the right side based on the readout pulse input from the image sensor driving unit 20 during driving. An element isolation region 44 made of a high-concentration p-type impurity diffusion layer is formed on the left side of the positive charge storage region 43a and the electron storage region 43b. The element isolation region 44 is separated from the positive charge storage region 43a and the electron storage region 43b. Similarly, a charge transfer region 45a and a p-type impurity diffusion layer 45b for reading the signal charge of the photoelectric conversion unit of the pixel adjacent to the positive charge storage region 43a and the electron storage region 43b are provided. .

  On the surface side of the semiconductor substrate 41, a charge transfer electrode 52 made of polysilicon or the like is provided via an interlayer insulating film 51b. In the imaging device 11 of the present embodiment, the charge transfer electrode 52 functions as a vertical charge transfer electrode that transfers signal charges read from the photoelectric conversion unit in the vertical direction during driving.

  A light shielding film 53 such as tungsten or aluminum is formed on the charge transfer electrode 52 via an interlayer insulating film 51a. In the light shielding film 53, an opening 54 having a predetermined opening area is formed above the positive charge accumulation region 43a and the electron accumulation region 43b. The opening 54 can be formed by forming a light shielding film 53 on the entire surface of the semiconductor substrate 41, forming a predetermined pattern by a photolithography process, and removing the light shielding film 53 by etching.

  A transparent insulating layer 51 is laminated above the light shielding film 53, and a color filter 61 is formed on the upper surface of the insulating layer 51. The color filter 61 includes an R filter that transmits red component light, a G filter that transmits green component light, and a B filter that transmits blue component light. Further, the color filter 61 may include a luminance filter that can transmit light having all color components.

  As the luminance filter, for example, an ND filter, a transparent filter, a white filter, a gray filter, or the like can be used. In addition, it is possible to adopt a configuration in which incident light is directly incident on the light receiving surface without providing anything above the light receiving surface of the photoelectric conversion unit. It can be said that it was provided.

  On the surface of the color filter 61, an upward convex microlens 64 having a curved surface protruding to the side irradiated with incident light is provided.

  In the imaging device 11 of the present embodiment, pixels in the imaging region are arranged in a Bayer array. Specifically, as shown in FIG. 2, an R pixel having an R color filter, a G pixel having a G color filter, and a B pixel having a B color filter are two-dimensionally arranged with respect to the imaging region. It is a pattern that is arranged. Specifically, in the vertical direction of FIG. 2, a column in which R pixels and G pixels are alternately arranged vertically and a column in which G pixels and B pixels are alternately arranged vertically are arranged in the horizontal direction. Are arranged alternately. Here, the same pixels are arranged so as not to be adjacent in the vertical direction and the horizontal direction.

  At the time of imaging, the imaging device 11 can acquire color information for each pixel using R pixels, G pixels, and B pixels, and can form a color image with the imaging device.

  In the imaging device 11 of the present embodiment, a vertical charge transfer unit is extended between the columns of arranged pixels along the direction of arrow V in FIG. A horizontal charge transfer unit (not shown) is connected to the transfer direction end of each vertical charge transfer unit, and the signal charge transferred along the horizontal charge transfer unit is output from the output amplifier.

  FIG. 4 is a plan view schematically showing a part of the imaging region of the imaging device 11. FIG. 4 shows a state of a portion including two pixels in the vertical direction and the horizontal direction. In FIG. 4, a broken-line rectangular portion indicated by an arrow U indicates a region where a photoelectric conversion unit of a unit pixel (unit cell) is formed. Since incident light enters the photoelectric conversion unit from the opening 54 provided in the unit pixel, in the present invention, the opening region of the opening 54 corresponds to the light receiving region in plan view.

  In the present embodiment, the position of the center of gravity of the opening 54 of the light shielding film 53 formed in the unit pixel region U is provided at a random position for each pixel, and the pixel arrangement is irregular when viewed from all pixels. become. In other words, the position of the light receiving region where the incident light is incident on the photoelectric conversion unit of each pixel is provided at a position shifted from the adjacent pixels.

  As shown in FIG. 4, the position of the center of gravity of the opening 54 in the unit pixel is digitized as position information, and can be stored in advance in the storage unit 35 of the imaging apparatus. The position information can be quantified as, for example, coordinates on the XY plane. In the present embodiment, as shown in FIG. 4, the upper left corner of the unit pixel is used as a reference, and the X coordinate (X11, X12, X21, X22) and Y coordinate of the center of the opening 54 from this reference are determined for each pixel. Coordinate information defined by (Y11, Y12, Y21, Y22) is set and stored in the storage unit 35. Note that the position information for digitizing the shift amount is not limited to the coordinate information of the present embodiment. Further, the position serving as a predetermined reference and the pixel serving as a reference when defining coordinate information are not particularly limited.

  Further, the configuration of the imaging device according to the present invention is such that when the deviation vector V indicating the position of the center of gravity g1 of the light receiving region (the opening in FIG. 4) with respect to the center of gravity g0 of the photoelectric conversion unit is defined, the deviation vector V is at least It differs from either the shift vector of the light receiving region adjacent in the vertical direction or the shift vector of the light receiving region adjacent in the horizontal direction. Information of these deviation vectors V may be stored in the storage unit 35 for each pixel.

  FIG. 5 is a diagram for explaining the displacement of the position of the opening 54 for each pixel. In the present embodiment, as shown in FIGS. 5A to 5C, the photoelectric conversion units 43 are arranged on the semiconductor substrate at a plurality of equal intervals, and the positions of the openings 54 of the light shielding film 53 are defined as pixels. Everything is shifted. When shifting the light receiving area of adjacent pixels as in this embodiment, for example, when a light receiving area is formed for a predetermined pixel as shown in FIG. 5A, the vertical and horizontal directions of the pixel are set. The light receiving areas of adjacent pixels are configured to be shifted from the light receiving areas in FIG. 5A as shown in FIG. 5B or 5C. In FIG. 5, for the sake of simplification of description, the state in which the light receiving region is shifted in either the vertical direction or the horizontal direction has been described. However, in the present embodiment, the light receiving region is arranged in the vertical direction or the horizontal direction. It is shifted. Here, in the present invention, “vertical direction” and “lateral direction” are a first linear direction defined in a two-dimensional plane and a second linear direction orthogonal to the first linear direction. can do. When the vertical direction is the first linear direction, the horizontal direction is the second linear direction, and when the vertical direction is the second linear direction, it means that the horizontal direction is the first linear direction.

  When manufacturing the image pickup device 11 of the present embodiment, the light shielding film 53 is once formed on the entire surface so as to cover the photoelectric conversion portion on the semiconductor substrate, and then the mask pattern having an array in which the positions of the openings 54 are shifted. Exposure and etching are removed by a photolithographic process using the. By doing so, the position of the center of gravity of the opening 54 of the light shielding film 53 is shifted at least in the horizontal direction with respect to the light receiving region adjacent in the vertical direction and vertically with respect to the light receiving region adjacent in the horizontal direction. It is possible to obtain a configuration provided at any position displaced in the direction.

  According to the present invention, the light receiving area of each pixel in the imaging area is provided at a position shifted from the light receiving area of the adjacent pixels in the vertical direction, the horizontal direction, or both the vertical direction and the horizontal direction. Yes. Then, the entire arrangement of the pixels becomes an irregular arrangement, and it is possible to suppress the occurrence of color moire and luminance moire that can be seen when the pixels are regularly arranged.

  In addition, it is preferable that the imaging apparatus includes a storage unit that stores position information indicating the shift amount of the light receiving area of each of the plurality of pixels. When the microlens 64 is formed on the surface of the image sensor 11 on which the incident light is irradiated, it is difficult to arrange the microlens 64 at a position shifted according to the shift amount of the light receiving region. Therefore, it is possible to correct the image by performing a numerical calculation based on the positional information indicating the amount of deviation for random variations in sensor sensitivity due to the regular arrangement of the microlenses 64.

  In the imaging device 11 of the present embodiment, the position of the light receiving region of each pixel is shifted by providing the opening 54 of the light shielding film 53 at a position shifted from at least one of the adjacent pixels in the vertical direction and the horizontal direction. Although the configuration is adopted, the configuration in which the position of the light receiving region is shifted is not limited to this. As shown in FIG. 6, each of the plurality of photoelectric conversion units 43 is shifted from the position of the photoelectric conversion unit 43 of the pixel adjacent to either the vertical direction or the horizontal direction on the surface of the semiconductor substrate. By providing, the position of the light receiving region of each pixel can be substantially shifted.

  Next, 2nd Embodiment concerning this invention is described based on drawing. The configuration of the imaging apparatus of this embodiment is basically the same as the configuration of FIG. 1 of the above embodiment, and only the configuration of the imaging device is different. In the following description of the second embodiment, the configuration of the imaging device will be specifically described.

  FIG. 7 is a cross-sectional view showing the configuration of the image sensor of the second embodiment. The imaging device includes a plurality of stacked impurity diffusion layers and includes a photoelectric conversion layer that generates signal charges by photoelectric conversion. In the drawing, the upper surface is referred to as “front surface”, and the lower surface is referred to as “back surface”. The imaging device of this embodiment is a so-called back-illuminated imaging device that emits light from the back side of a semiconductor substrate, photoelectrically converts incident light by a photoelectric conversion region on the front side, and generates and outputs a signal charge. It is.

The photoelectric conversion layer is adjacent to the silicon oxide film (SiO ₂ ) 126, the silicon layer 122 that functions as a seed layer during epitaxial growth, and the surface of the silicon layer 122 in order from the back surface side to the front surface side. A light shielding film 124 provided at the boundary between pixels, a high concentration p + type impurity diffusion layer 121 formed in a region where the light shielding film 124 is not provided on the surface of the silicon layer 122, the impurity diffusion layer 121, and the light shielding And an epitaxial layer 119 made of p-type silicon having an impurity concentration lower than that of the impurity diffusion layer 121 so as to cover the film 124. In this embodiment, the space between the light shielding films 124 functions as an opening, and the opening area when the opening is viewed in plan from the light incident side is defined as a light receiving area.

  The light shielding film 124 is made of, for example, a metal material, and the outside is covered with an insulating film 123 made of an insulating material. In this embodiment, the insulating film 123 may be formed by performing heat treatment on the light shielding film 124, or a silicide oxide film of a metal material may be used.

  The image pickup device of the present embodiment has a configuration in which a wiring circuit is provided so that a negative voltage is applied to the light shielding film 124 during driving, and the silicon layer 122 on the back surface side can be grounded with respect to the light shielding film 124. In this way, when the light shielding film 124 is made of a conductive material such as a metal material, it is possible to prevent the generation of electric charges with the surrounding active layer.

  In the photoelectric conversion layer, an n− type impurity diffusion layer 118 having a low impurity concentration is stacked on the surface of the epitaxial layer 119 in each pixel region. Each of the n − -type impurity diffusion layers 118 is provided to be separated from an adjacent pixel by an element isolation region 117 formed by a p + -type impurity diffusion layer having a high impurity concentration. On the surface side of the n − -type impurity diffusion layer 118, an n-type impurity diffusion layer 114 and a p + -type impurity diffusion layer 113 having a high impurity concentration are stacked in a partial region of the pixel region. A p-type impurity diffusion layer 116 having an impurity concentration lower than that of the p + -type impurity diffusion layer 113 is formed in the remaining region. The p-type impurity diffusion layer 116 is formed adjacent to the stacked portion of the impurity diffusion layer 114 and the p + -type impurity diffusion layer 113 with the same thickness and in the horizontal direction (left-right direction in FIG. 5). Yes. In addition, a high-concentration n-type impurity diffusion layer 115 is formed in a state where a part of the surface of the p-type impurity diffusion layer 116 is exposed.

  Through the insulating film functioning as the gate insulating film on the surface of the p + -type impurity diffusion layer 113 and the p-type impurity diffusion layer 116 (including the impurity diffusion layer 115 exposed on the surface of the p-type impurity diffusion layer 116). An insulating layer 111 is formed. On the back surface of the insulating layer 111, a charge transfer region 112 such as a vertical charge transfer portion (VCCD) is formed. In the present embodiment, the CCD image sensor type charge reading structure is used. However, the present invention is not particularly limited thereto. For example, if the signal charge accumulated in the photoelectric conversion layer can be read and transferred, for example, a CMOS image sensor type. It is also possible to have a structure for reading the charges. In the case of the CMOS image sensor type, multilayer wiring electrodes are formed on the insulating layer 111.

  An antireflection film 127 is formed on the back surface side of the photoelectric conversion layer with a silicon oxide film 126 interposed therebetween. Further, on the back surface of the antireflection film 127, a color filter 128 is formed in which a plurality of color filters that transmit light of different wavelengths are arranged in a matrix with respect to the back surface. The configuration of the color filter 128 can be the same as in the above embodiment. Further, on the back surface of the color filter 128, an upwardly convex microlens that is curved so that the lens surface protrudes on the light incident side may be formed.

  In the imaging element, the ratio of the thickness T of the photoelectric conversion layer to the pixel size W is preferably 4 or more. In other words, it is preferable that T / W ≧ 4. Here, the pixel size W corresponds to the length of one side of the pixel region partitioned in a square shape (the length in the left-right direction in FIG. 7) when viewed from the back side (or the front side). The pixel size is preferably 2 μm square or less. By doing so, it is possible to increase the thickness of the photoelectric conversion layer to improve the optical sensitivity and miniaturize the pixels.

  At the time of driving, light enters from the back side of the photoelectric conversion layer of the image sensor, passes through the color filter 128, and is irradiated to the inside of the photoelectric conversion layer. When incident light enters the photoelectric conversion layer, signal charges are generated by photoelectric conversion. The generated signal charge is temporarily stored in the impurity diffusion layer 114. When a readout pulse is applied to the electrode 112 during readout, the accumulated signal charge is read out and transferred to the charge transfer unit 115. At this time, since the light shielding film 124 is formed as an embedding member at the boundary between adjacent pixels in the photoelectric conversion layer, it is possible to prevent light transmitted through the color filter 128 from entering the surrounding pixel region. Can do.

  FIG. 8 is a cross-sectional view illustrating a modification of the image sensor according to the present embodiment. This imaging device is different from the imaging device shown in FIG. 7 in the structure of the light shielding film 135 formed as an embedded member on the silicon layer 126 and the structure of the epitaxial layer around the light shielding film 135. Hereinafter, the different parts will be described.

  As shown in FIG. 8, a light shielding film 135 made of a metal material or the like is formed on the surface of the silicon oxide film 126 at the boundary between adjacent pixels. The light shielding film 135 is covered with a p + type epitaxial layer 131 having a high impurity concentration. Here, the layer covering the light shielding film 135 is not limited to the epitaxial layer 131, and any other epitaxial layer or impurity diffusion layer may be used as long as it is a non-depletion layer that does not generate charges at the interface with the light shielding film 135. . The light shielding film 135 is connected to a ground circuit so that it can be fixed at 0 V during driving. In this case, when the light shielding film 135 is made of a conductive member such as a metal material, it is not necessary to form an insulating film outside the metal material portion as in the structure shown in FIG. It is possible to suppress the generation of electric charges with the active layer. Note that an insulating film may be formed outside the metal material portion and the light shielding film 135 may be covered with a non-depletion layer. By so doing, it is possible to more significantly suppress the generation of electric charges with the active layer around the light shielding film 135.

  The area between the light shielding films 135 functions as an opening, and the opening area of the opening corresponds to the light receiving area in a state where the imaging area is viewed in plan.

  FIG. 9 is a simplified diagram for explaining the displacement of the position of the opening for each pixel. FIG. 9 shows only three unit pixels arranged in a predetermined direction of the imaging region. In the present embodiment, a plurality of unit pixels U are arranged at equal intervals in the two-dimensional direction of the imaging region, and the position of the center of gravity of the opening H of the light shielding film 124 is shifted for each unit pixel U. In the case of shifting the light receiving area of adjacent pixels as in the present embodiment, for example, when the light receiving area is formed by shifting the left unit pixel to the left end in the horizontal direction as shown in FIG. The center unit pixel U in the figure is provided with the light receiving region shifted to the right side with respect to the horizontal direction, and the right side unit pixel U in the figure is further in the horizontal direction than the center unit pixel U. The light receiving area is shifted on the right side. In FIG. 9, for the sake of simplification of description, the state in which the light receiving region is shifted only in one of the vertical direction and the horizontal direction is shown and described. However, in the present embodiment, two-dimensionally in the vertical direction and the horizontal direction. The light receiving area is shifted.

  Similarly to the above-described embodiment, the image sensor according to the present embodiment may be configured to include a storage unit that stores position information indicating the amount of shift of the light receiving area of each of the plurality of pixels.

Next, the manufacturing method of the image sensor of this embodiment will be described based on the drawings.
10 to 13 are diagrams for explaining the procedure of the manufacturing method of the image sensor. First, as shown in FIG. 10A, a silicon substrate S and a silicon oxide film (SiO ₂ ) 151 are formed on the surface of the silicon substrate S, and function as an epitaxial seed layer on the silicon oxide film 151. A silicon layer 152 to be formed is formed. A semiconductor wafer having an SOI (Silicon on Insulator) structure including the silicon oxide film 151 and the silicon layer 152 may be prepared in advance. Another insulating film can be used for the silicon oxide film (SiO ₂ ) 151.

  As shown in FIG. 10B, the alignment mark 154 and the light shielding film 156 are patterned on the surface of the silicon layer 52 using a light shielding material. The alignment mark 154 and the light shielding film 156 can be patterned as the same layer all together with the same mask using the same light shielding material. Further, the alignment mark 154 and the light shielding film 156 may be formed by a method in which a light shielding material is deposited after a resist pattern is formed by a photolithography process, and then the photoresist is peeled off and lifted off. In this way, the silicon layer 152 is not damaged by etching.

  In the present embodiment, after the light shielding film 156 is formed on the entire surface of the silicon layer 152, a mask pattern having an array in which the positions of the centers of gravity of the openings partitioned between the light shielding films 156 are shifted for each pixel is formed. Let's remove exposure and etching by the photolithography process used. By doing so, it is possible to obtain a configuration in which the positions of the openings of the light shielding film 156 vary between unit pixels.

    As shown in FIG. 10C, an epitaxial layer 158 is formed on the silicon layer 152 by performing epitaxial growth by an epitaxial lateral overgrowth (Epitaxial Lateral Overgrowth = ELO) method. By doing so, the alignment mark 154 and the light shielding film 156 formed on the surface of the silicon layer 152 can be embedded in the epitaxial layer 158. In the present application, the alignment mark 154 and the light shielding film 156 are collectively referred to as an embedded member.

  As shown in FIG. 11A, the second alignment mark 164 is formed on the surface of the epitaxial layer 158. The second alignment mark 164 is formed on the epitaxial layer 158 using an exposure apparatus having an alignment function using infrared light with reference to the position of the first alignment mark 154 formed on the back surface side of the epitaxial layer 158. The first alignment mark 154 is detected from the surface side, and is formed by a LOCOS (Local Oxidation of Silicon) method or an STI (Shallow Trench Isolation) method. The second alignment mark 164 can be formed using the same light-shielding material as the first alignment mark 154.

  After forming the second alignment mark 164, an insulating film 161 is formed on the surface of the epitaxial layer 158 by a CVD (Chemical Vapor Deposition) method or the like.

  As shown in FIG. 11B, a sensor region 166 is formed that is aligned with the second alignment mark 164 formed on the surface of the epitaxial layer 158 as a reference. In this embodiment, the CCD image sensor type charge transfer electrode 168 is provided as an example, but the present invention is not limited to this, and a CMOS image sensor type configuration may be used.

  As shown in FIG. 12A, a transparent adhesive 172 is applied to the surface of the insulating film 161 on the surface side of the epitaxial layer 158, and a support substrate 174 is attached.

  Further, the SOI silicon substrate S stacked on the back surface of the epitaxial layer 158 is removed by etching with potassium hydroxide (KOH) or the like to expose the silicon oxide film 151 on the back surface.

  As shown in FIG. 12B, an antireflection film 175 is formed on the silicon oxide film 151 exposed on the back surface side of the epitaxial layer 158. Then, a color filter 176 having a plurality of color filters that transmit light of different wavelengths is formed on the antireflection film 175. The color filter 176 is provided with (red) R, (green) G, and (blue) B colors in a matrix in a state where a plurality of color filters are viewed from the back side.

  In addition, as illustrated in FIG. 13, the light shielding portion 182 may be formed on the antireflection film 175 using the same light shielding material as the light shielding film 156. At this time, the light shielding portion 182 is provided at the boundary between adjacent pixels at the interface between the color filter 176 and the antireflection film 175.

  Further, a third alignment mark 178 may be formed on the antireflection film 175. The third alignment mark 178 may be a single layer made of the same light-shielding material as the light-shielding portion 182 and may be patterned simultaneously with one mask. Further, at the same time as the light shielding portion 182, an optical black portion 184 for removing a direct current component of dark current based on the signal of the effective pixel and the difference may be formed. The light shielding part 182 and the third alignment mark 178 may be formed on the silicon oxide film 151.

  In addition, according to the above procedure, an SOI substrate is provided with an embedded member, and light is irradiated from the surface side, which is suitable for an image pickup device that takes an image by reading out signal charges generated inside from the surface side from the surface side of the substrate. A semiconductor substrate can be manufactured.

  According to the present invention, the light receiving area of each pixel in the imaging area is provided at a position shifted from the light receiving area of the adjacent pixel. Then, the entire arrangement of the pixels becomes an irregular arrangement, and it is possible to suppress the occurrence of color moire and luminance moire that can be seen when the pixels are regularly arranged.

In addition, this invention is not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.
For example, in the above-described embodiment, the photoelectric conversion units are arranged in a lattice shape at a predetermined pitch in the vertical direction and the horizontal direction with respect to the surface of the semiconductor substrate. However, as shown in FIG. In the honeycomb arrangement shown in FIG. 14, photoelectric conversion units 243 are arranged on the surface of a semiconductor substrate in columns that are equivalent in the vertical direction and in rows that are equivalent in the horizontal direction, and the photoelectric conversion units 243 of the columns are arranged in adjacent columns. With respect to the photoelectric conversion part 243, it is shifted by a 1/2 pitch in the vertical direction. Here, the position of the center of gravity of the opening 254 formed on each photoelectric conversion unit 243 is at least shifted laterally with respect to the light receiving region adjacent in the vertical direction, and light reception adjacent in the horizontal direction. It is provided at one of the positions shifted in the vertical direction with respect to the region. By doing so, even if the arrangement of the photoelectric conversion units 243 is a honeycomb arrangement, an effect of suppressing color moire can be obtained as in the above embodiment.

It is a block diagram of an imaging device provided with the imaging device concerning this invention. It is the top view which showed simply the pixel arrangement | sequence in the imaging region of an image pick-up element. FIG. 3 is a cross-sectional view taken in the direction of arrow AA in the pixel array of FIG. 2. It is the top view which showed typically a part of imaging region of an image sensor. It is a figure for demonstrating the shift | offset | difference of the position of the opening part for every pixel. It is a figure for demonstrating the shift | offset | difference of the position of the photoelectric conversion part for every pixel. It is sectional drawing which shows the structure of the image pick-up element of 2nd Embodiment. It is sectional drawing which shows the modification of the image pick-up element of 2nd Embodiment. It is a simplified diagram for explaining a shift in position of an opening for each pixel. It is a figure explaining the procedure of the manufacturing method of an image pick-up element. It is a figure explaining the procedure of the manufacturing method of an image pick-up element. It is a figure explaining the procedure of the manufacturing method of an image pick-up element. It is a figure explaining the procedure of the manufacturing method of an image pick-up element. It is a figure explaining the example of the honeycomb arrangement | positioning of a photoelectric conversion part.

Explanation of symbols

11 Image sensor 53, 156 Light shielding film 54 Opening

Claims (13)

An image sensor in which a surface of a semiconductor substrate is provided with a first linear direction and a plurality of photoelectric conversion units arranged in a second linear direction orthogonal to the first linear direction,
The light receiving area in the photoelectric conversion unit is at least shifted in the second linear direction with respect to the light receiving area adjacent in the first linear direction, and in the light receiving area adjacent in the second linear direction. On the other hand, the imaging device is provided at one of the positions shifted in the first linear direction.   The light incident surface of the photoelectric conversion unit is covered with a light-shielding film having an opening on each of the photoelectric conversion units, and the opening has a center of gravity adjacent to at least the first linear direction. Any one of the position shifted in the second linear direction with respect to the center of gravity of the part and the position shifted in the first linear direction with respect to the center of gravity of the opening adjacent to the second linear direction The imaging device according to claim 1, wherein the imaging device is provided on the imaging device.   Each of the plurality of photoelectric conversion units is at least displaced in the second linear direction with respect to the photoelectric conversion unit adjacent in the first linear direction, and the adjacent in the second linear direction. The imaging device according to claim 1, wherein the imaging element is provided at any one of positions shifted in the first linear direction with respect to a photoelectric conversion unit.   The image sensor according to any one of claims 1 to 3, wherein a color filter is provided on a surface of the photoelectric conversion unit on which light is incident. An imaging device that forms an image by generating signal charges by photoelectrically converting incident light for each of a plurality of pixels provided in an imaging region of an imaging element,
The image sensor is
A plurality of photoelectric conversion units arranged on the surface of the semiconductor substrate in a first linear direction and a second linear direction orthogonal to the first linear direction;
The position of the light receiving region in the photoelectric conversion unit is shifted at least in the second linear direction with respect to the light receiving region adjacent in the first linear direction, and the light receiving adjacent in the second linear direction. An imaging apparatus, wherein the imaging apparatus is provided at any one of positions shifted in the first linear direction with respect to a region.   The upper portion of the photoelectric conversion unit is covered with a light-shielding film having an opening on each of the photoelectric conversion units, and the center of gravity of the opening is at least relative to the center of gravity of the opening adjacent to the first linear direction. Provided either at a position shifted in the second linear direction or a position shifted in the first linear direction with respect to the center of gravity of the opening adjacent to the second linear direction. The imaging apparatus according to claim 5.   The plurality of photoelectric conversion units are at least shifted in the second linear direction with respect to the photoelectric conversion units adjacent in the first linear direction, and the photoelectrics adjacent in the second linear direction. The imaging apparatus according to claim 5, wherein the imaging apparatus is provided at any one of positions shifted in the first linear direction with respect to the conversion unit.   The imaging apparatus according to claim 5, further comprising a storage unit that stores position information indicating a shift amount of the light receiving region of each of the plurality of pixels.   9. The position information is coordinate information indicating a shift amount with respect to a first linear direction provided in the imaging region and a second linear direction orthogonal to the first linear direction. The imaging device described.   The imaging apparatus according to claim 8, wherein the storage unit is a mask ROM.   9. The image pickup apparatus according to claim 8, wherein the storage unit is an EEPROM.   The image pickup device according to claim 5, wherein the image pickup device is provided with a color filter on a surface of the image pickup region irradiated with the incident light. An image sensor in which a surface of a semiconductor substrate is provided with a first linear direction and a plurality of photoelectric conversion units arranged in a second linear direction orthogonal to the first linear direction,
The shift vector indicating the position of the center of gravity of the light receiving region with respect to the center of gravity of the photoelectric conversion unit is at least a shift vector of the light receiving region adjacent to the first linear direction and a shift of the light receiving region adjacent to the second linear direction An imaging device characterized by being different from any of vectors.

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