Light detection element

Abstract

The present invention relates to a light detection element capable of suppressing a sensitivity difference between pixels in an image sensor having a phase detection autofocus (PDAF) structure. A light detection element according to the present invention comprises: a pixel array unit formed by arranging pixels, each n * n pixels among the pixels constituting a pixel group including color filters of the same color, n being a natural number of 2 or more; two or more phase difference detection pixels adjacent to each other, the two or more phase difference detection pixels being provided to replace a part of conventional pixels arranged in the pixel array unit; and a light shielding portion provided for each of the pixel groups constituted by the conventional pixels, the conventional pixels including surrounding pixels arranged around the phase difference detection pixel, the width or shape of the light shielding portion being different according to an image height. The present invention can be applied, for example, to a CMOS image sensor.

Description

Technical Field

[0001] This disclosure relates to a light detection element, and more specifically to a light detection element capable of suppressing sensitivity differences between pixels in an image sensor having a PDAF structure. Background Technology

[0002] Patent document 1 discloses a solid-state imaging device that adjusts the sensitivity of pixels by changing the opening of a light-shielding film formed in the upper layer relative to the photoelectric conversion unit according to the image height, thereby improving image quality even in image distributions with complex corrections such as Gr / Gb step difference and color shading.

[0003] In addition, Patent Document 2 discloses a solid-state imaging device that, in response to color mixing caused by pupil correction, changes the linewidth of the light-shielding film according to the correction amount of pupil correction (i.e., image height), thereby suppressing the occurrence of color mixing paths. Citation List Patent documents

[0004] Patent Document 1: JP 2017-059739 A Patent Document 2: JP 2023-002902 A Summary of the Invention Technical issues

[0005] In the prior art, a known image sensor includes conventional pixels and phase difference detection pixels, and has a phase detection autofocus (PDAF) structure, in which a common on-chip lens is formed for multiple phase difference detection pixels. However, the aforementioned patent documents do not consider image sensors with a PDAF structure.

[0006] This disclosure is made in view of this situation and is intended to be able to suppress sensitivity differences between pixels in an image sensor with a PDAF structure. Solution to the problem

[0007] The light detection element disclosed herein includes: a pixel array unit formed by arranging pixels, wherein every n×n pixels constitute a pixel group including a color filter of the same color, where n is a natural number of 2 or more; two or more adjacent phase difference detection pixels, wherein the two or more phase difference detection pixels are configured to replace a portion of the conventional pixels arranged in the pixel array unit; and a light-shielding portion provided for each pixel group composed of the conventional pixels, wherein the conventional pixels include surrounding pixels arranged around the phase difference detection pixels, and the width or shape of the light-shielding portion varies according to the image height.

[0008] In this disclosure, a pixel array unit is formed by an arrangement of pixels, wherein each n×n pixel group comprises a pixel group including a color filter of the same color; two or more adjacent phase difference detection pixels are configured to replace a portion of the conventional pixels arranged in the pixel array unit; and for each pixel group composed of the conventional pixels, a light-shielding portion with a width or shape varying according to the image height is provided, wherein the conventional pixels include surrounding pixels arranged around the phase difference detection pixels. Attached Figure Description

[0009] Figure 1 This is a diagram illustrating an example of the construction of a CMOS image sensor. Figure 2 This is a top view showing an example of the construction of a pixel array unit. Figure 3 This is a diagram showing an example of the cross-sectional construction of a regular pixel and a phase difference detection pixel. Figure 4 This is a top view showing an example of a shared on-plate lens. Figure 5 This is a top view showing an example of a shared on-plate lens. Figure 6 This diagram illustrates the problem when the surrounding pixels do not have a light-shielding film applied. Figure 7 This is a diagram illustrating an example of the construction of a pixel array unit according to a first embodiment of the present disclosure. Figure 8 This is a diagram showing an example of the first light-shielding film. Figure 9 This is a diagram showing an example of the first light-shielding film. Figure 10 This is a diagram illustrating an example of how the first light-blocking film changes according to the image height. Figure 11 This is a diagram illustrating an example of how the first light-blocking film changes according to the image height. Figure 12 This is a diagram used to illustrate the structure of the second light-shielding film. Figure 13 This is a diagram illustrating an example of the construction of a pixel array unit according to a second embodiment of the present disclosure. Figure 14 This is a diagram illustrating an example of the construction of a pixel array unit according to a third embodiment of the present disclosure. Figure 15 This is a diagram illustrating an example of the construction of a pixel array unit according to a fourth embodiment of the present disclosure. Figure 16 This is a diagram illustrating an example of the construction of a pixel array unit according to a fifth embodiment of the present disclosure. Figure 17 This is a diagram illustrating an example of the construction of a pixel array unit according to a sixth embodiment of the present disclosure. Figure 18 This is a diagram showing an example of a cross-sectional structure of a portion of a pixel region. Figure 19 This is a diagram showing another example of a cross-sectional construction of a portion of a pixel region. Detailed Implementation

[0010] The following describes a method for carrying out the present invention (hereinafter referred to as "embodiments"). The specific description will be presented in the following order.

[0011] 1. Example of CMOS image sensor construction 2. PDAF structure and application of image height-dependent shading. 3. First embodiment (pixel array unit of 2×2 pixels) 3-1. First light-shielding film used to correct the Gr / Gb ratio 3-2. Second light-shielding film used to correct sensitivity differences between colors. 4. Second embodiment (including the light-shielding characteristics of the light-shielding part in the pixel group of surrounding pixels) 5. Third embodiment (3×3 pixel array unit) 6. Fourth embodiment (pixel array unit of 4×4 pixels) 7. Fifth Embodiment (including waveguide construction) 8. Sixth Embodiment (Construction for Improving the Sensitivity of the Green Pixel Group)

[0012] 1. Example of CMOS image sensor construction The technology disclosed herein relates to a light detection element comprising a pixel array unit arranged by pixels, wherein every n×n pixels (n being a natural number greater than 2) constitute a pixel group including a color filter. The pixel array unit includes conventional pixels and phase difference detection pixels, and has a phase detection autofocus (PDAF) structure in which a common on-chip lens is formed for multiple phase difference detection pixels.

[0013] Figure 1 This is a diagram illustrating an example of the construction of a complementary metal-oxide-semiconductor (CMOS) image sensor that employs a light detection element according to the technology disclosed herein.

[0014] The CMOS image sensor 10 is, for example, a back-illuminated solid-state imaging device, and includes a pixel array unit 21 formed on a semiconductor substrate (chip) (not shown) and peripheral circuit units integrated on the same semiconductor substrate as the pixel array unit 21.

[0015] The peripheral circuit units include, for example, a vertical drive unit 22, a column processing unit 23, a horizontal drive unit 24, and a system control unit 25.

[0016] The CMOS image sensor 10 includes a signal processing unit 28 and a data storage unit 29. The signal processing unit 28 and the data storage unit 29 may be disposed on the semiconductor substrate constituting the CMOS image sensor 10, or they may be disposed on a different substrate than the semiconductor substrate constituting the CMOS image sensor 10.

[0017] In the construction of pixel array unit 21, multiple unit pixels (hereinafter referred to as pixels) are arranged along the row and column directions, that is, arranged in a two-dimensional matrix. Each unit pixel includes a photoelectric conversion unit, which generates and accumulates a charge corresponding to the amount of light received.

[0018] Here, the row direction is the direction in which pixels are arranged in a pixel row (horizontal direction), which is the horizontal direction in the figure, while the column direction is the direction in which pixels are arranged in a pixel column (vertical direction), which is the vertical direction in the figure.

[0019] In pixel array unit 21, pixel driving lines 26 are connected along the row direction to each row of the matrix pixel array, and vertical signal lines 27 are connected along the column direction to each column of the matrix pixel array. Pixel driving lines 26 are signal lines used to provide driving signals (control signals) for driving pixels, such as driving signals for reading signals from pixels. One end of pixel driving line 26 is connected to the output terminal of vertical driving unit 22 corresponding to each row.

[0020] Here, to better illustrate the accompanying diagram, one pixel driving line 26 is drawn for each pixel row, but in reality, there are multiple pixel driving lines 26 connected to each pixel row.

[0021] The vertical drive unit 22 includes, for example, a shift register and an address decoder, and drives the pixels of the pixel array unit 21 in a simultaneous, row-by-row, or other manner. For example, the vertical drive unit 22 includes two scanning systems: a readout scanning system and a clear scanning system.

[0022] The readout scanning system sequentially selects and scans the unit pixels of the pixel array unit 21 line by line to read out the signal from the unit pixel.

[0023] The clearing scan system performs a clearing scan on the read rows of the read-out scan system at a predetermined timing. The clearing scan of the clearing scan system removes unwanted charges from the photoelectric conversion units of the unit pixels in the read rows, thereby resetting the photoelectric conversion units.

[0024] For each pixel column, the signal output from the corresponding unit pixel in the pixel row selected and scanned by the vertical driving unit 22 is input to the column processing unit 23 through the vertical signal line 27.

[0025] For each pixel column of pixel array unit 21, column processing unit 23 performs predetermined signal processing on the signal provided from the corresponding pixel in the selected row through vertical signal line 27, and temporarily saves the pixel signal after signal processing.

[0026] For example, column processing unit 23 performs signal processing (noise cancellation processing, correlated double sampling (CDS) processing, and analog-to-digital (AD) conversion processing, etc.). For example, CDS processing can eliminate fixed-pattern noise specific to each pixel, such as reset noise and threshold variations of amplifying transistors in the pixel.

[0027] The horizontal drive unit 24 includes a shift register and an address decoder, and sequentially selects the unit circuits in the column processing unit 23 corresponding to the pixel columns. Through the selective scanning of the horizontal drive unit 24, the signal-processed pixel signals of each unit circuit in the column processing unit 23 are sequentially output to the signal processing unit 28.

[0028] The system control unit 25 includes a timing generator that generates various timing signals, and performs drive control on the vertical drive unit 22, column processing unit 23, and horizontal drive unit 24 based on the generated timing signals.

[0029] The signal processing unit 28 has at least arithmetic processing functions and performs various signal processing operations, such as arithmetic processing, on the pixel signals output by the column processing unit 23. When the signal processing unit 28 performs signal processing, the data storage unit 29 temporarily stores the data required for processing.

[0030] 2. PDAF structure and application of image height-dependent shading. PDAF structure As described above, the CMOS image sensor 10 includes conventional pixels and phase difference detection pixels, and has a PDAF structure in which a common on-chip lens is formed for multiple phase difference detection pixels.

[0031] Figure 2 This is a top view of a portion of the pixel region 21P, including the phase difference detection pixel, extracted from the pixel array unit 21 included in the CMOS image sensor 10. Figure 3 It shows along Figure 2 The diagram shows an example of a cross-section constructed by the line segment A-A'.

[0032] In pixel region 21P, regular pixels 30 are arranged in a matrix, and two or more adjacent phase difference detection pixels 40 are used to replace a portion of the regular pixels 30. In pixel array unit 21 including pixel region 21P, every n×n pixels of regular pixels 30 ( Figure 2 In the example, n=2) constitutes a pixel group PG including a color filter. That is, in pixel array unit 21, color filters colored with any one of red (R), green (G) and blue (B) and arranged according to the Bayer array are formed to cover each pixel group PG.

[0033] like Figure 3 As shown, each conventional pixel 30 is composed of a separate on-chip lens 31, a color filter 32, an inter-pixel light-blocking structure 33, and a photoelectric conversion unit 34, starting from the upper surface side (incident surface side).

[0034] To more effectively direct incident light to the photoelectric conversion unit 34 in the lower layer, a separate on-chip lens 31 is formed for each pixel in the on-chip lens layer LE. The color filter 32 is formed as a color filter corresponding to the color of the pixel group PG including the corresponding conventional pixels 30, which allows incident light of a specific wavelength to pass through in the direction toward the lower layer.

[0035] The inter-pixel light-shielding structure 33 is made of a metallic material or the like to reduce optical color mixing between adjacent pixels. The photoelectric conversion unit 34 includes a photodiode that generates and accumulates charge based on incident light passing through a separate on-chip lens 31 and a color filter 32. Although not shown in the figures, a signal wiring layer is formed in the layer below the photoelectric conversion unit 34 for reading out the signal charge generated and accumulated by the photoelectric conversion unit 34 and outputting the signal charge to subsequent stages. Furthermore, a light-shielding film LS is provided below the inter-pixel light-shielding structure 33 as a light-shielding portion to which the technology according to this disclosure can be applied.

[0036] On the other hand, the phase difference detection pixel 40 is composed of a common on-chip lens 41, a color filter 32, an inter-pixel light-blocking structure 33, and a photoelectric conversion unit 34, sequentially formed in the on-chip lens layer LE, starting from the upper surface side (incident surface side). Note that all the color filters constituting the phase difference detection pixel 40 are green filters.

[0037] Figure 4 This is a top view showing an example of a shared on-plate lens 41.

[0038] like Figure 4 As shown, the shared on-chip lens 41 is formed to cover multiple ( Figure 4 In the example, there are two adjacent phase difference detection pixels (40). That is, in Figure 2 and Figure 3In the example shown, the two phase difference detection pixels 40 share a common on-chip lens 41.

[0039] Note that no inter-pixel light-blocking structure 33 is formed between the regular pixels 30 or between the regular pixels 30 and the phase difference detection pixels 40 sharing the on-chip lens 41. However, an inter-pixel light-blocking structure 33 may be formed between the multiple phase difference detection pixels 40 sharing the on-chip lens 41.

[0040] In the CMOS image sensor 10, which includes conventional pixels 30 and phase difference detection pixels 40, the conventional pixels 30 enable high-resolution and high-image-quality image capture. Furthermore, since the phase difference detection pixels 40 utilize the light-gathering capability of the shared on-chip lens 41 for phase difference detection without the need for a light-blocking structure, they can perform phase difference detection with high sensitivity and good separation characteristics. Moreover, since there are no obstacles in the optical path that could scatter or diffract light, color mixing between adjacent pixels that may occur due to light scattering or diffraction can be suppressed, thereby preventing image quality degradation.

[0041] Figure 5 This is a top view showing another example of a shared on-plate lens 41.

[0042] When the shared on-chip lens 41 is formed using the same manufacturing method as the individual on-chip lens 31, the individual on-chip lens 31 fills the plane, resulting in almost no gaps between adjacent pixels, and its shape is essentially quadrilateral. In contrast, Figure 5 The shared on-chip lens 41 is basically hexagonal. Therefore, no gap is formed between the light-gathering element structure (on-chip lens) of the conventional pixel 30 and the phase difference detection pixel 40, thereby improving the sensitivity of the phase difference detection pixel 40.

[0043] Application of shading based on image height Figure 6 A top view is shown of pixel regions 21H, 21V, and 21HV extracted in a direction away from the center position (i.e., the center of the image height) of the light-receiving surface of the pixel array unit 21 in a direction toward the end of the image height.

[0044] Pixel region 21H is a pixel region horizontally to the left of the image height center position of pixel array unit 21, and pixel region 21V is a pixel region vertically downward from the image height center position of pixel array unit 21. Pixel region 21HV is a pixel region diagonally downward to the left from the image height center position of pixel array unit 21.

[0045] In all pixel regions 21H, 21V, and 21HV, in addition to the regular pixel 30, a phase difference detection pixel 40 is also included. As described above, since the phase difference detection pixel 40 includes a green filter, the pixel group that includes the green filter and is adjacent to the phase difference detection pixel 40 (hereinafter referred to as the green pixel group, etc.) consists of five pixels, while the blue pixel group adjacent to the phase difference detection pixel 40 consists of three pixels.

[0046] Furthermore, in pixel regions 21H, 21V, and 21HV, the surrounding pixels 30s arranged around the phase difference detection pixel 40 are shown in gray. In addition to the ten pixels adjacent to and surrounding the phase difference detection pixel 40, the surrounding pixels 30s also include two pixels that are further away from the two pixels adjacent to the phase difference detection pixel 40 in the horizontal direction (left and right directions, respectively).

[0047] Here, we will consider applying the image height-dependent shading portion to the pixel array unit 21, which includes a pixel group of 2×2 pixels and has a PDAF structure.

[0048] like Figure 6 As shown, in pixel regions 21H, 21V, and 21HV, for each pixel group including color filters of the same color, a first light-shielding film LS1 and a second light-shielding film LS2 are provided as light-shielding parts with different widths or shapes depending on the image height.

[0049] Although the detailed construction will be described below, the first light-shielding film LS1 is a light-shielding portion formed in the green pixel group and used to correct the sensitivity ratio (hereinafter referred to as the Gr / Gb ratio) of the green pixel group adjacent to the red pixel group and the green pixel group adjacent to the blue pixel group in the row direction. The first light-shielding film LS1 is formed to adjust and reduce the sensitivity of the green pixel group adjacent to the blue pixel group when viewed from the center of the image height. The first light-shielding film LS1 only needs to be formed between the on-chip lens layer LE of each pixel constituting the green pixel group and the photoelectric conversion unit 34.

[0050] The second light-shielding film LS2 is a light-shielding component formed in the red pixel group and used to correct the sensitivity differences (hereinafter referred to as inter-color sensitivity differences) between the pixels constituting the red pixel group. The second light-shielding film LS2 is formed to compensate for the sensitivity corresponding to incident light leakage from the green pixel group adjacent to the red pixel group. The second light-shielding film LS2 only needs to be formed between the on-chip lens layer LE of each pixel constituting the red pixel group and the photoelectric conversion unit 34.

[0051] Here, in each pixel region 21H, 21V, and 21HV, the surrounding pixels 30s are adjacent to the phase difference detection pixel 40, therefore their output characteristics may differ from those of the regular pixels 30 that are not adjacent to the phase difference detection pixel 40. Therefore, as... Figure 6 As shown, in each pixel region 21H, 21V and 21HV, the pixel group including the surrounding pixel 30s is not provided with a light-shielding part (first light-shielding film LS1 or second light-shielding film LS2) that depends on the image height.

[0052] However, in this case, the pixel group including the surrounding pixels for 30 seconds is relatively more sensitive than the surrounding pixel group of the same color.

[0053] Specifically, in each pixel region 21H, 21V, and 21HV, pixel p1 in the green pixel group, including the surrounding pixel 30s, is more sensitive than the regular pixels 30 that make up the surrounding green pixel group. Furthermore, in each pixel region 21H, 21V, and 21HV, pixel p2 in the red pixel group, including the surrounding pixel 30s, is more sensitive than the other regular pixels 30 that make up the same red pixel group.

[0054] Therefore, the pixel group including the surrounding 30s was detected as a high-brightness pixel group with a greater amount of light than other pixel groups (hereinafter referred to as bright spots).

[0055] Therefore, the light detection element using the technology of this disclosure provides a light-shielding portion with a different width or shape depending on the image height for each pixel group (including surrounding pixels arranged around the phase difference detection pixel) composed of conventional pixels.

[0056] 3. First embodiment (pixel array unit of 2×2 pixels) Figure 7 This is a diagram illustrating a construction example of the pixel array unit 21 according to a first embodiment of the present disclosure.

[0057] With Figure 6 In a similar way, Figure 7 A top view is shown of pixel regions 21H, 21V, and 21HV extracted in a direction away from the center position (i.e., the center of the image height) of the light-receiving surface of the pixel array unit 21 in a direction toward the end of the image height.

[0058] However, with Figure 6 The difference is that, in Figure 7 In each pixel region 21H, 21V, and 21HV shown, the pixel group including the surrounding pixel 30s is also provided with a light-shielding part (first light-shielding film LS1 or second light-shielding film LS2) that depends on the image height. Note that the phase difference detection pixel 40 is not provided with a light-shielding part (first light-shielding film LS1 or second light-shielding film LS2) that depends on the image height.

[0059] Based on the above structure, the sensitivity difference between the pixel group including the surrounding pixels 30s and the surrounding pixel group of the same color excluding the surrounding pixels 30s can be suppressed. Therefore, the pixel group including the surrounding pixels 30s can be prevented from being detected as a bright spot with a greater amount of light than other pixel groups.

[0060] Here, the first light-shielding film LS1 and the second light-shielding film LS2 are described in detail.

[0061] 3-1. First light-shielding film used to correct the Gr / Gb ratio Figure 8 This is a diagram showing an example of the first light-shielding film LS1 of a pixel group.

[0062] The first light-shielding film LS1 is formed in a rectangular shape and covers the pixel group, and its interior includes an opening 101. For example... Figure 8 As shown, the length from the upper side of the first light-shielding film LS1 to the upper side of the opening 101 is the light-shielding length a, and the length from the right side of the first light-shielding film LS1 to the right side of the opening 101 is the light-shielding length b. The length from the lower side of the first light-shielding film LS1 to the lower side of the opening 101 is the light-shielding length c, and the length from the left side of the first light-shielding film LS1 to the left side of the opening 101 is the light-shielding length d.

[0063] When light is collected at the center of the opening 101, the first light-shielding film LS1 can reduce sensitivity by moving any one side toward the center. That is, to adjust the sensitivity reduction, it is not necessary to move all sides simultaneously; adjustment can be made by moving only a specific side. In this way, by treating each side individually as an adjustment parameter, the adjustment parameter can be adjusted for each pixel group, and the opening can be represented by the ratio of the side lengths that varies according to the image height and their associated shape. Therefore, complex distributions within the viewing angle can be corrected.

[0064] Although detailed descriptions are omitted, in the technology according to this disclosure, correction is performed individually by setting the parameter for correcting the distribution of Gr / Gb ratios increasing from left to right to shading length a, the parameter for correcting the distribution increasing from right to left to shading length b, the parameter for correcting the distribution increasing from bottom to top to shading length c, and the parameter for correcting the distribution increasing from top to bottom to shading length d, based on the image height. Therefore, the opening 101 is formed by a combination of shading lengths a to d, thus allowing correction of complex shapes in the Gr / Gb ratio distribution.

[0065] These shading lengths can be corrected by coordinates, for example, based on the following equations (1) to (4). Here, A to L are constants, and x and y within the viewpoint represent the lateral and longitudinal coordinates, respectively.

[0066] Shielding length a = Ay 2 +By+C (1) Shielding length b = Dx 2 +Ex+F (2) Shielding length c=Gy 2 +Hy+I (3) Shielding length d=Jx 2 +Kx+L (4)

[0067] In equations (1) to (4) above, the lateral distribution is offset by shading lengths b and d, and the longitudinal distribution is offset by shading lengths a and c. However, these assignments and formulas are arbitrary and do not necessarily have to be as described above. For example, the equations can be cubic or quartic, or the same equation can include parameters x and y simultaneously (e.g., shading length a = Ay). 2 +Bxy+Cy 2 +D, etc. The shape does not have to change linearly; it can also change non-linearly.

[0068] Since the shading length is controlled independently, the aperture ratio can be varied; however, the aperture ratio does not necessarily change. For example, even if the shading length a increases, the aperture ratio can remain constant if the shading length b decreases (i.e., the shape changes). Furthermore, when the contribution rates of shading lengths a and b to sensitivity are different, adjustments can be made without changing the aperture ratio.

[0069] As pixel size decreases, aperture width and light wavelength gradually become similar. If the aperture ratio is changed too easily, the wavelengths that can pass through will be limited, thus affecting spectral characteristics. However, the solution according to this disclosure allows for adjustment of sensitivity while maintaining the aperture ratio. Of course, the aperture ratio can also be changed.

[0070] To achieve more complex adjustments, simply add a reference. Figure 8 The number of "sides" can be specified. For example, such as Figure 9 As shown, the opening 101 of the first light-shielding film LS1 can be formed as an octagon. Furthermore, as... Figure 10 As shown, in the first light-shielding film LS1-1 of pixel group PG-1 located at the center of the image height, the opening 101-1 is formed as a rectangle, but the number of sides can be increased according to the image height; in the first light-shielding film LS1-2 of pixel group PG-2, the opening 101-2 can be formed as a polygon (e.g., an octagon) with five or more sides. Of course, the number of sides can also be reduced according to the image height.

[0071] like Figure 11 As shown, the side to be changed can be limited based on the image height or quadrant. Figure 11 In the example, all four sides of the opening 101-2 formed in the pixel group PG-2 located at the center of the image height have the same width. Conversely, only the light-shielding length b is changed in the pixel group PG-1 located on the left side of the quadrant, and only the light-shielding length a is changed in the pixel group PG-2 located on the right side of the quadrant. Furthermore, the light-shielding film disclosed in Patent Document 1 can be applied to the first light-shielding film LS1 as needed.

[0072] In this way, the side length ratio and shape of the opening 101 can be adjusted according to the image height. That is, the Gr / Gb ratio can be adjusted for each pixel group, and adjustments can be made for each color (Gr / Gb, i.e., the color of the filter of the adjacent pixel group).

[0073] 3-2. Second light-shielding film used to correct sensitivity differences between colors. Figure 12 This is a diagram used to illustrate the structure of the second light-shielding film LS2.

[0074] Figure 12 A cross-sectional view of four pixels from the group of green pixels PG_G and red pixels PG_R that form adjacent groups of pixels is shown. Figure 12 In the example, the center of the image height is located on the right side of the image.

[0075] like Figure 12 As shown in A, in the configuration where the second light-shielding film LS2 is not formed, the inter-pixel light-shielding structure 33 formed between adjacent regular pixels exists between the green pixel group PG_G and the red pixel group PG_R.

[0076] In this configuration, when light strikes each regular pixel, depending on the amount of pupil correction, light may leak from a regular pixel located in the green pixel group PG_G and adjacent to the red pixel group PG_R to regular pixel 30R-1, which constitutes the red pixel group PG_R. In this case, regular pixel 30R-1 becomes more sensitive than regular pixel 30R-2, which constitutes the same red pixel group PG_R.

[0077] Therefore, in a pixel group, the second light-shielding film LS2 is formed in a regular pixel far from the image height center among the regular pixels adjacent to another pixel group. That is, as... Figure 12As shown in B, the second light-shielding film LS2 is formed in a regular pixel 30R-1 located in the red pixel group GP_R and adjacent to the green pixel group PG_G. In this case, within the red pixel group GP_R, the second light-shielding film LS2 is formed to extend along its boundary with the green pixel group PG_G. Note that the width of the second light-shielding film LS2 only needs to be adjusted according to the correction amount for pupil correction (i.e., the amount of light leaking from the green pixel group PG_G to the regular pixel 30R-1 based on the image height).

[0078] Using this structure, by suppressing the incident light of the regular pixel 30R-1, the sensitivity corresponding to the incident light leakage of the green pixel group PG_G can be offset. Thus, the inter-color sensitivity difference between regular pixels 30R-1 and 30R-2 in the red pixel group GP_R can be suppressed.

[0079] 4. Second embodiment (including the light-shielding characteristics of the light-shielding part in the pixel group of surrounding pixels) Figure 13 An example of the construction of a pixel array unit 21 according to a second embodiment of the present disclosure is shown.

[0080] As shown in the pixel array unit 21 according to the first embodiment Figure 7 , Figure 13 A top view is shown of pixel regions 21H, 21V, and 21HV extracted in a direction away from the center position (i.e., the center of the image height) of the light-receiving surface of the pixel array unit 21 in a direction toward the end of the image height.

[0081] However, with Figure 7 The difference is that, in Figure 13 In each pixel region 21H, 21V, 21HV shown, the pixel group including the surrounding pixel 30s is provided with a light-shielding part (first light-shielding film LS1' or second light-shielding film LS2'), the light-shielding characteristics of which are different from the light-shielding characteristics of the pixel group located at the same image height and excluding the surrounding pixel 30s.

[0082] Unlike the first light-shielding film LS1 and the second light-shielding film LS2 disposed on the pixel group excluding the surrounding pixels 30s, the first light-shielding film LS1' and the second light-shielding film LS2' have light-shielding characteristics corresponding to the output characteristics of the surrounding pixels 30s. The light-shielding characteristics mentioned here are characteristics that directly affect the Gr / Gb ratio and the amount of sensitivity difference correction between the same color, and can be the width, shape, or material of the light-shielding component, etc.

[0083] According to the above structure, even when the signal output from the surrounding pixels 30s is different from the output signal of other conventional pixels 30 due to the influence of the phase difference detection pixel 40, the influence can be mitigated.

[0084] 5. Third embodiment (3×3 pixel array unit) Figure 14 This is a diagram illustrating a construction example of the pixel array unit 21 according to a third embodiment of the present disclosure.

[0085] Figure 14 A, B, and C in the figure show top views of pixel regions 21H, 21V, and 21HV located away from the center of the light-receiving surface of the pixel array unit 21 (i.e., the center of the image height) in a direction toward the end of the image height.

[0086] like Figure 14 As shown, in pixel regions 21H, 21V, and 21HV, the pixel group including the color filter of the same color is a pixel group of 3×3 pixels.

[0087] In a manner similar to pixel array unit 21, which comprises pixel groups of 2×2 pixels, in Figure 14 In all the pixel regions 21H, 21V and 21HV shown, in addition to the regular pixel 30, there is also a phase difference detection pixel 40.

[0088] exist Figure 14 In each pixel region 21H, 21V, and 21HV shown, the image height-dependent light-shielding portion (first light-shielding film LS1 or second light-shielding film LS2) is provided not only on the pixel group excluding the surrounding pixels 30s, but also on the pixel group including the surrounding pixels 30s. Note that the phase difference detection pixel 40 is not provided with the image height-dependent light-shielding portion (first light-shielding film LS1 or second light-shielding film LS2).

[0089] Based on the above configuration, even in a pixel array unit 21 comprising a pixel group of 3×3 pixels, the sensitivity difference between a pixel group including the surrounding pixels 30s and a surrounding pixel group of the same color excluding the surrounding pixels 30s can be suppressed. Therefore, it is possible to prevent the pixel group including the surrounding pixels 30s from being detected as a bright spot with a greater amount of light than other pixel groups.

[0090] 6. Fourth embodiment (pixel array unit of 4×4 pixels) Figure 15 This is a diagram illustrating an example of the construction of a pixel array unit 21 according to a fourth embodiment of the present disclosure.

[0091] Figure 15 A, B, and C in the figure show top views of pixel regions 21H, 21V, and 21HV located away from the center of the light-receiving surface of the pixel array unit 21 (i.e., the center of the image height) in a direction toward the end of the image height.

[0092] like Figure 15As shown, in pixel regions 21H, 21V, and 21HV, the pixel group including the color filter of the same color is a pixel group of 4×4 pixels.

[0093] In a manner similar to pixel array unit 21, which comprises pixel groups of 2×2 pixels, in Figure 15 In all pixel regions 21H, 21V, and 21HV shown, in addition to the regular pixel 30, a phase difference detection pixel 40 is also included. However, in Figure 15 In the example, four pairs of two adjacent phase difference detection pixels 40 are set up to be housed in a pixel group (green pixel group).

[0094] exist Figure 15 In each pixel region 21H, 21V, and 21HV shown, the image height-dependent light-shielding portion (first light-shielding film LS1 or second light-shielding film LS2) is provided not only on the pixel group excluding the surrounding pixels 30s, but also on the pixel group including the surrounding pixels 30s. Note that the phase difference detection pixel 40 or the pixel group including the phase difference detection pixel 40 is not provided with the image height-dependent light-shielding portion (first light-shielding film LS1 or second light-shielding film LS2).

[0095] Based on the above configuration, even in a pixel array unit 21 comprising a pixel group of 4×4 pixels, the sensitivity difference between a pixel group including the surrounding pixels 30s and a surrounding pixel group of the same color excluding the surrounding pixels 30s can be suppressed. Therefore, it is possible to prevent the pixel group including the surrounding pixels 30s from being detected as a bright spot with a greater amount of light than other pixel groups.

[0096] 7. Fifth Embodiment (including waveguide construction) Figure 16 This is a diagram illustrating a construction example of the pixel array unit 21 according to a fifth embodiment of the present disclosure.

[0097] Figure 16 A cross-sectional view is shown of pixel 30G, which is part of the green pixel group, and pixel 30R, which is part of the red pixel group adjacent to pixel 30G.

[0098] exist Figure 16 In the example, waveguide 131 is formed between the color filter 32 of pixel 30G and the color filter 32 of pixel 30G, so that the photoelectric conversion unit 34 can be penetrated from the on-chip lens layer LE. Waveguide 131 serves as the aforementioned inter-pixel light-shielding structure 33, and is made of, for example, SiN, SiO2, SiON, styrene-based resin material, acrylic-based resin material, styrene-acrylic copolymer-based resin material, or siloxane-based resin material.

[0099] A protective film 132 is formed around the waveguide 131 to protect it. Furthermore, metal films 133 and 134 are formed directly below the waveguide 131 (on the side of the photoelectric conversion unit 34) as light-shielding portions for which the technology according to this disclosure can be applied. The metal films 133 and 134 are made of Ti, TiN, or W, and function as absorbers to absorb light incident from the outside.

[0100] Based on the above construction, the incident path of light incident on each pixel constituting the pixel array unit 21 is determined, so that color mixing between pixels can be suppressed at the boundary between pixel groups including filters of different colors.

[0101] 8. Sixth Embodiment (Construction for Improving the Sensitivity of the Green Pixel Group) Figure 17 This is a diagram illustrating a construction example of the pixel array unit 21 according to a sixth embodiment of the present disclosure.

[0102] Figure 17 A, B, and C in the figures show top views of pixel regions 21H, 21V, and 21HV located away from the center of the light-receiving surface of the pixel array unit 21, which comprises a pixel group of 2×2 pixels, in a direction toward the end of the image height (i.e., the center of the image height).

[0103] like Figure 17 As shown, in each pixel region 21H, 21V and 21HV, the green pixel group PG_G with a thinner thickness of the light-shielding wall (inter-pixel light-shielding structure 33) formed for the four pixels constituting the green pixel group PG_G is represented in gray.

[0104] Specifically, in the pixel region 21H located at the center of the image height away from the pixel array unit 21 in the horizontal direction, the light-shielding walls of the pixels constituting the green pixel group PG_G adjacent to the red pixel group PG_R in the row direction are adjusted to be thinner.

[0105] In addition, in the pixel region 21V located at the center of the image height away from the pixel array unit 21 in the vertical direction, the light-shielding wall of the pixel constituting the green pixel group PG_G adjacent to the blue pixel group PG_B in the row direction is adjusted to be thinner.

[0106] In addition, in the pixel region 21HV located at the center of the image height away from the pixel array unit 21 along the diagonal direction, the light-shielding walls of the pixels constituting all green pixel groups PG_G are adjusted to be thinner.

[0107] Figure 18 It is shown Figure 17 The diagram shows an example of the cross-sectional construction of pixel region 21H along line segment a-a'.

[0108] like Figure 18 As shown, the light-shielding wall 151GG between pixels constituting the green pixel group PG_G is thinner than the light-shielding wall 151RR between pixels constituting the red pixel group PG_R. Furthermore, the light-shielding walls 151GR and 151RG between pixels constituting the green pixel group PG_G and pixels constituting the red pixel group PG_R are thinner on the side corresponding to the pixel constituting the green pixel group PG_G. Note that the light-shielding wall 151GR corresponds to the second light-shielding film LS2 described above.

[0109] According to the above structure, by adjusting the light-shielding walls of the pixels constituting the green pixel group to be thinner according to the direction starting from the center of the image height of the pixel array unit 21, the sensitivity of the green pixel group can be improved, since the sensitivity of the green pixel group tends to decrease.

[0110] Figure 19 It is shown Figure 17 The diagram shows an example of another cross-sectional construction of pixel region 21H along line segment a-a'.

[0111] exist Figure 19 In the example, not only the light-shielding wall formed for the pixels constituting the green pixel group PG_G, but also the rear deep trench isolation portion (RDTI) used to isolate the photoelectric conversion units 34 of the pixels from each other is formed to be thinner.

[0112] Specifically, such as Figure 19 As shown, the RDTI 152GG between pixels constituting the green pixel group PG_G is thinner than the RDTI 152RR between pixels constituting the red pixel group PG_R. Furthermore, the RDTI 152GR and 152RG between pixels constituting the green pixel group PG_G and pixels constituting the red pixel group PG_R are thinner on the side corresponding to the pixels constituting the green pixel group PG_G.

[0113] According to the above structure, by adjusting the light-shielding wall and RDTI of the pixels constituting the green pixel group to be thinner according to the direction from the center of the image height of the pixel array unit 21, the sensitivity of the green pixel group can be improved, thus the sensitivity of the green pixel group tends to decrease.

[0114] Furthermore, the above embodiments can be combined appropriately.

[0115] Typically, the technology according to this disclosure can be applied to optical detection elements, including distance measuring sensors (also known as time-of-flight (ToF) sensors) and solid-state imaging devices as CMOS image sensors. A distance measuring sensor is a sensor that emits illumination light toward an object, detects the reflected light returning due to the reflection of the illumination light on the object's surface, and calculates the distance to the object based on the time of flight from emitting the illumination light to receiving the reflected light. The pixel structure of the distance measuring sensor can adopt the structure of the pixel array unit 21 described above.

[0116] The effects described in this manual are illustrative only and are not limiting. Other effects may also exist.

[0117] Furthermore, the embodiments applying the technology according to this disclosure are not limited to the above embodiments, and various modifications can be made without departing from the spirit of the technology according to this disclosure.

[0118] Furthermore, this disclosure may have the following structure. (1) A photodetector element, comprising: A pixel array unit is formed by arranging pixels, and each n×n pixel in the pixel array constitutes a pixel group including a color filter of the same color, where n is a natural number greater than 2. Two or more adjacent phase difference detection pixels, wherein the two or more phase difference detection pixels are configured to replace a portion of the conventional pixels arranged in the pixel array unit; and A light-shielding portion is provided for each of the pixel groups consisting of the conventional pixels, the conventional pixels including surrounding pixels arranged around the phase difference detection pixel, the width or shape of the light-shielding portion varying according to the image height. (2) According to the optical detection element described in (1), wherein, The phase difference detection pixel is not provided with the light-blocking part. (3) According to the optical detection element described in (2), wherein, The pixel group including the phase difference detection pixel is not provided with the light-shielding part. (4) The light detection element according to any one of (1) to (3), comprising: An on-chip lens layer comprising a shared on-chip lens formed for every two or more adjacent phase difference detection pixels and a separate on-chip lens formed for each of the conventional pixels, including the surrounding pixels. (5) The optical detection element according to (4), wherein, The boundary between the individual on-chip lens formed in the conventional pixel and the shared on-chip lens formed in the phase difference detection pixel is substantially quadrilateral or substantially hexagonal. (6) The optical detection element according to (4) or (5), wherein, Two or more adjacent phase difference detection pixels include a set green filter. (7) The optical detection element according to (4) or (5), wherein, Two or more adjacent phase difference detection pixels are configured to be housed in one pixel group. (8) The light detection element according to any one of (4) to (7), wherein, The light-blocking characteristics of the light-blocking portion disposed on the first pixel group including the surrounding pixels are different from the light-blocking characteristics of the second pixel group which exists at the same image height but does not include the surrounding pixels. (9) The optical detection element according to (8), wherein, The light-blocking characteristics of the light-blocking portion provided on the first pixel group correspond to the output characteristics of the surrounding pixels. (10) The light detection element according to any one of (4) to (9), wherein, The light-shielding portion includes an opening formed in the upper layer of the photoelectric conversion unit included in each pixel constituting the pixel group for each pixel group, and the side length ratio and shape of the opening vary according to the image height. (11) The optical detection element according to (10), wherein, The light-shielding portion is formed in the pixel group including the green filter. (12) The optical detection element according to (10) or (11), wherein, The side length ratio is adjusted for each color of the color filter in the adjacent pixel group. (13) The light detection element according to any one of (10) to (12), wherein, The light-shielding portion is formed between the on-sheet lens layer and the photoelectric conversion unit. (14) The light detection element according to any one of (10) to (13), wherein, The number of sides forming the opening varies depending on the image height. (15) The light detection element according to any one of (10) to (13), wherein, The shape and aperture ratio of the opening vary depending on the image height. (16) The light detection element according to any one of (10) to (13), wherein, The opening ratio remains constant, and only the shape of the opening varies according to the image height. (17) The optical detection element according to (4) to (9), wherein, The light-blocking portion is formed in a regular pixel that is far from the center of the image height among the regular pixels adjacent to the other pixel groups in one of the pixel groups. (18) The optical detection element according to (17), wherein, The light-shielding portion is formed in the conventional pixels adjacent to the pixel group including the red filter in the pixel group including the green filter. (19) The optical detection element according to (18), wherein, The light-shielding portion is formed to extend along the boundary with the pixel group including the green filter. (20) The light detection element according to any one of (17) to (19), wherein, The light-shielding portion is formed between the on-sheet lens layer and the photoelectric conversion unit included in each pixel constituting the pixel group. List of reference numerals

[0119] 10 CMOS image sensor; 21 Pixel array unit; 30 Conventional pixels; 30 Surrounding pixels; 31 Independent on-chip lens; 32 Color filter; 33 Inter-pixel light-shielding structure; 34 Photoelectric conversion unit; 40 Phase difference detection pixel; 41 Shared on-chip lens; 101 Opening; 131 Waveguide; 151GG, 151GR, 151RG light-shielding walls; 152GG, 152GR, 152RGRDTI; LS1 First light-shielding film; LS2 Second light-shielding film.

Claims

1. A photodetector element, comprising: A pixel array unit is formed by arranging pixels, and each n×n pixel in the pixel array constitutes a pixel group including a color filter of the same color, where n is a natural number greater than 2. Two or more phase difference detection pixels that are adjacent to each other, wherein the two or more phase difference detection pixels are configured to replace a portion of the conventional pixels arranged in the pixel array unit; as well as A light-shielding portion is provided for each of the pixel groups consisting of the conventional pixels, the conventional pixels including surrounding pixels arranged around the phase difference detection pixel, the width or shape of the light-shielding portion varying according to the image height.

2. The optical detection element according to claim 1, wherein, The phase difference detection pixel is not provided with the light-blocking part.

3. The optical detection element according to claim 2, wherein, The pixel group including the phase difference detection pixel is not provided with the light-shielding part.

4. The photodetector element according to claim 1, comprising: An on-chip lens layer comprising a shared on-chip lens formed for every two or more adjacent phase difference detection pixels and a separate on-chip lens formed for each of the conventional pixels, including the surrounding pixels.

5. The optical detection element according to claim 4, wherein, The boundary between the individual on-chip lens formed in the conventional pixel and the shared on-chip lens formed in the phase difference detection pixel is substantially quadrilateral or substantially hexagonal.

6. The optical detection element according to claim 4, wherein, Two or more adjacent phase difference detection pixels include the green filter.

7. The optical detection element according to claim 4, wherein, Two or more adjacent phase difference detection pixels are configured to be housed in one pixel group.

8. The optical detection element according to claim 4, wherein, The light-blocking characteristics of the light-blocking portion disposed on the first pixel group including the surrounding pixels are different from the light-blocking characteristics of the second pixel group which exists at the same image height but does not include the surrounding pixels.

9. The optical detection element according to claim 8, wherein, The light-blocking characteristics of the light-blocking portion provided on the first pixel group correspond to the output characteristics of the surrounding pixels.

10. The optical detection element according to claim 4, wherein, The light-shielding portion includes an opening formed in the upper layer of the photoelectric conversion unit included in each pixel constituting the pixel group for each pixel group, and the side length ratio and shape of the opening vary according to the image height.

11. The optical detection element according to claim 10, wherein, The light-shielding portion is formed in the pixel group including the green filter.

12. The optical detection element according to claim 10, wherein, The side length ratio is adjusted for each color of the color filter in the adjacent pixel group.

13. The optical detection element according to claim 10, wherein, The light-shielding portion is formed between the on-sheet lens layer and the photoelectric conversion unit.

14. The optical detection element according to claim 10, wherein, The number of sides forming the opening varies depending on the image height.

15. The optical detection element according to claim 10, wherein, The shape and aperture ratio of the opening vary depending on the image height.

16. The optical detection element according to claim 10, wherein, The opening ratio remains constant, and only the shape of the opening varies according to the image height.

17. The optical detection element according to claim 4, wherein, The light-blocking portion is formed in a regular pixel that is far from the center of the image height among the regular pixels adjacent to the other pixel groups in one of the pixel groups.

18. The optical detection element according to claim 17, wherein, The light-shielding portion is formed in the conventional pixels adjacent to the pixel group including the red filter in the pixel group including the green filter.

19. The optical detection element according to claim 18, wherein, The light-shielding portion is formed to extend along the boundary with the pixel group including the green filter.

20. The optical detection element according to claim 17, wherein, The light-shielding portion is formed between the on-sheet lens layer and the photoelectric conversion unit included in each pixel constituting the pixel group.

Images