KR20230011192A - Image sensing device - Google Patents

Abstract

An image sensing device according to one embodiment of the present technology may include a pixel array in which image pixels and phase detection pixel pairs are arranged so that the phase detection pixel pairs in which a plurality of phase detection pixels are arranged adjacently are positioned between the image pixels. The pixel array may include: photoelectric conversion regions formed in a substrate to correspond to the image pixels and the phase detection pixels; device isolation structures positioned between adjacent photoelectric conversion regions within the substrate; color filters positioned on the substrate to correspond to the image pixels and the phase detection pixel pairs; a first grid structure positioned between color filters of a first image pixel and a first phase detection pixel pair that are adjacent to each other among the image pixels and the phase detection pixel pairs, and shifted by a first distance from a device isolation structure positioned between a photoelectric conversion region of the first image pixel and a photoelectric conversion region of the first phase detection pixel pair; and a second grid structure positioned on a color filter of the first phase detection pixel pair and shifted by a second distance different from the first distance from a device isolation structure positioned between photoelectric conversion regions of the first phase detection pixel pair. Thus, it is possible to improve phase detection characteristics.

Description

Image sensing device {IMAGE SENSING DEVICE}

The present invention relates to an image sensing device including phase detection pixels.

An image sensor is a device that converts an optical image into an electrical signal. Recently, with the development of computer and communication industries, demand for image sensors with improved integration and performance in various fields such as digital cameras, camcorders, PCS (Personal Communication System), video game devices, security cameras, medical micro cameras, robots, etc. is increasing.

An embodiment of the present invention is to provide an image sensing device capable of improving phase detection characteristics.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

An image sensing device according to an embodiment of the present invention includes a pixel array in which image pixels and phase detection pixel pairs are arranged so that phase detection pixel pairs in which a plurality of phase detection pixels are adjacently disposed are positioned between image pixels. wherein the pixel array includes photoelectric conversion regions formed in a substrate corresponding to the image pixels and the phase detection pixels, device isolation structures positioned between adjacent photoelectric conversion regions in the substrate, and the image pixels. color filters positioned on the substrate to correspond to the pixels and the phase detection pixel pairs, and a color filter of a first image pixel and a first phase detection pixel pair positioned adjacent to each other among the image pixels and the phase detection pixel pairs a first grid structure positioned between photoelectric conversion regions of the first image pixel and shifted by a first distance from an element isolation structure positioned between photoelectric conversion regions of the first image pixel and photoelectric conversion regions of the first phase detection pixel pair; and and a second grid structure positioned on the color filter of the phase detection pixel pair and shifted by a second distance different from the first distance from an element isolation structure positioned between the photoelectric conversion regions of the first phase detection pixel pair. there is.

An image sensing device according to another embodiment of the present invention includes a pixel array in which image pixels and phase detection pixel pairs are arranged such that phase detection pixel pairs in which a plurality of phase detection pixels are adjacently disposed are positioned between image pixels. wherein the pixel array includes a first grid structure positioned between the image pixels and between the image pixel and the phase detection pixel pair and a second grid structure positioned between the plurality of phase detection pixels; The second grid structure may be formed to have a different width from that of the first grid structure.

An image sensing device according to an embodiment of the present invention may improve phase detection characteristics by improving the structure of a grid structure of phase detection pixels.

1 is a block diagram schematically showing the configuration of an image sensing device according to an embodiment of the present invention;
FIG. 2 exemplarily shows a planar structure of a portion of the pixel array in FIG. 1; FIG.
Figure 3 is a cross-sectional view showing the state of one embodiment of the cross section cut along the line XX' in FIG.
4 is a flowchart for illustratively explaining a method of determining a location of a second grid structure positioned between phase detection pixels;
FIG. 5 exemplarily shows a phase detection pixel array to be formed within the pixel array of FIG. 1;
FIG. 6 exemplarily shows how the pixel array of FIG. 5 is divided into a plurality of sub-pixel regions;
7 exemplarily shows how to move the location of a grid structure between phase detection pixels;
8 is a diagram showing a range in which the position of a grid structure can be moved by way of example.
9 is a cross-sectional view showing another embodiment of a cross section taken along the line XX′ in FIG. 2;
10 exemplarily shows how to adjust the width of a grid structure between phase detection pixels;
FIG. 11 illustratively shows a planar structure of a portion of the pixel array in FIG. 1;
12A and 12B are diagrams exemplarily showing the shape of a microlens formed on unit pixels in a partial region including phase detection pixels in FIG. 11;

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing an embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function hinders understanding of the embodiment of the present invention, the detailed description will be omitted.

1 is a block diagram schematically illustrating the configuration of an image sensing device according to an embodiment of the present invention.

Referring to FIG. 1, the image sensing device includes a pixel array (100), a row driver (200), a correlated double sampler (CDS, 300), an analog-to-digital converter (analog digital converter, ADC 400), an output buffer 500, a column driver 600, and a timing controller 700. Here, each component of the image sensing device 100 is only exemplary, and at least some components may be added or omitted as needed.

The pixel array 100 may include a plurality of unit pixels arranged in a plurality of rows and a plurality of columns. In one embodiment, a plurality of unit pixels may be arranged in a two-dimensional pixel array including a plurality of rows and a plurality of columns. In another embodiment, a plurality of unit pixels may be arranged in a 3D pixel array. A plurality of unit pixels may generate an electrical signal by converting an optical signal on a unit pixel basis or on a pixel group basis, and unit pixels within a pixel group may share at least a specific internal circuit. A plurality of unit pixels may include a plurality of image pixels and a plurality of phase detection pixels. The plurality of image pixels may generate electrical signals by converting incident light, and may generate image signals corresponding to the photographing object as electrical signals. The phase detection pixels may generate electrical signals by converting incident light, and as electrical signals, may generate phase signals for calculating a phase difference between images captured by image pixels and generated.

The pixel array 100 may receive driving signals such as a row selection signal, a reset signal, and a transmission signal from the row driver 200 . Unit pixels are activated when a driving signal is received and may perform operations corresponding to row selection signals, reset signals, and transmission signals.

The row driver 200 may operate unit pixels based on control signals provided from a control circuit such as the timing controller 700 . The row driver 200 may select at least one unit pixel connected to at least one row line of the pixel array 100 . The row driver 200 may generate a row select signal for selecting at least one row line among a plurality of row lines. The row driver 200 may sequentially enable a reset signal and a transmission signal for unit pixels of the selected row line. Pixel signals generated from unit pixels of the selected row line may be output to the correlated double sampler 300 .

The correlated double sampler 300 may remove unwanted offset values of unit pixels using a correlated double sampling (CDS) method. For example, the correlated double sampler 300 compares output voltages of unit pixels obtained before and after photocharges generated by incident light are accumulated in a sensing node (floating diffusion node) to remove unwanted offset values of unit pixels. can Through this, it is possible to obtain a pixel signal generated only by incident light without a noise component. The correlated double sampler 300 sequentially samples and holds the voltage level of the reference signal and the voltage level of the pixel signal received from the pixel array 100 through the plurality of column lines based on the clock signal provided from the timing controller 700. can do. The correlated double sampler 300 may output the reference signal and the pixel signal to the analog-to-digital converter 400 as a correlated double sampling (CDS) signal.

The analog-to-digital converter 400 may convert the CDS signal received from the correlated double sampler 300 into a digital signal. The analog-to-digital converter 400 may include a ramp-comparison type analog-to-digital converter. The analog-to-digital converter 400 may generate a comparison signal by comparing the ramp signal provided from the timing controller 700 and the CDS signal provided from the correlated double sampler 200 with each other. The analog-to-digital converter 400 may count a level transition time of the comparison signal based on the ramp signal provided from the timing controller 700 and output the count value to the output buffer 500 .

The output buffer 500 may temporarily store data of each column unit provided from the analog-to-digital converter 300 under the control of the timing controller 170 . The output buffer 500 may operate as an interface that compensates for a difference in transmission (or processing) speed between the image sensing device and other connected devices.

The column driver 600 may select a column of the output buffer 500 under the control of the timing controller 700 and sequentially output data temporarily stored in the selected column of the output buffer 500 . When an address signal is received from the timing controller 700, the column driver 600 selects a column of the output buffer 500 by generating a column selection signal based on the address signal, thereby selecting the selected column of the output buffer 500. The image data of can be controlled to be output as an output signal.

The timing controller 700 may generate signals for controlling operations of the row driver 200 , the analog-to-digital converter 400 , the output buffer 500 and the column driver 600 . The timing controller 700 transmits a clock signal required for operation of each component of the image sensing device, a control signal for timing control, and an address signal for selecting a row or column to the row decoder 200, the column driver 600, It can be provided to the analog-to-digital converter 400 and the output buffer 500. According to embodiments, the timing controller 700 may include a logic control circuit, a phase lock loop (PLL) circuit, a timing control circuit, a communication interface circuit, and the like. can include

FIG. 2 is a diagram showing a planar structure of a portion of the pixel array in FIG. 1 as an example.

Referring to FIG. 2 , the pixel array 100 may include a plurality of unit pixels continuously arranged in a row direction and a column direction. The plurality of unit pixels may include a plurality of image pixels IPX and a plurality of phase detection pixel pairs PDPX.

The plurality of image pixels IPX may generate an image signal corresponding to a photographing object. The plurality of image pixels IPX include a red pixel PX_R generating an image signal corresponding to red color light and a green pixel PX_G generating an image signal corresponding to green color light. and a blue pixel PX_B generating an image signal corresponding to blue color light.

In the plurality of image pixels IPX, unit pixels having color filters of the same color may be adjacently arranged in the form of N×N (N is a natural number equal to or greater than 2). For example, the image pixels IPX include red sub-pixel blocks in which four red pixels PX_R are arranged in a 2×2 shape, and green sub-pixel blocks in which four green pixels PX_G are arranged in a 2×2 shape. blocks, and blue sub-pixel blocks in which four blue pixels PX_B are arranged in a 2×2 shape. The pixel array 100 may include a quad structure in which red sub-pixel blocks, green sub-pixel blocks, and blue sub-pixel blocks are arranged in a Bayer pattern.

The phase detection pixel pairs PDPX may be positioned between the image pixels IPX, and may generate phase signals for calculating a phase difference between images generated by capturing a photographing object. The phase detection pixel pairs PDPX may include two phase detection pixels disposed adjacent to each other in a horizontal direction (X direction) or a vertical direction (Y direction). For example, as shown in FIG. 2 , the phase detection pixel pairs PDPX may include a first phase detection pixel LPD and a second phase detection pixel RPD disposed adjacent to each other in a horizontal direction.

In FIG. 2, only the state in which the first and second phase detection pixels LPD and RPD are arranged adjacently in the horizontal direction is shown as an example, but the first and second phase detection pixels LPD and RPD are They may be arranged adjacently in a vertical direction. Alternatively, the phase detection pixel pairs PDPX may include four phase detection pixels disposed adjacently in vertical and horizontal directions so as to detect phase differences in both vertical and horizontal directions.

The first and second phase detection pixels LPD and RPD of the phase detection pixel pairs PDPX may include color filters of the same color. For example, as shown in FIG. 2 , the first and second phase detection pixels LPD and RPD may include green color filters. In FIG. 2, it is shown that one color filter is formed for each unit pixel (image pixel, phase detection pixel), but when unit pixels of the same color are adjacently arranged, one color filter spans the corresponding unit pixels. can be formed.

The first and second phase detection pixels LPD and RPD may be continuously formed at regular intervals in the horizontal and vertical directions in an array form.

In the pixel array 100, a grid structure may be formed between color filters of unit pixels to prevent cross-talk between adjacent color filters. At this time, the grid structure positioned between the first phase detection pixel (LPD) and the second phase detection pixel (RPD) is between the image pixels (IPX) and between the image pixel (IPX) and the phase detection pixel (LPD or RPD). It may have a structure different from the grid structure in which it is located. In addition, the position and width of the grid structure positioned between the first phase detection pixel LPD and the second phase detection pixel RPD may be determined by other phase detection pixels around the corresponding phase detection pixels and corresponding phase detection pixels. It may be determined based on the sensitivity of image pixels having the same color filter as the pixels. A description of how the position and width of the grid structure located between the first phase detection pixel LPD and the second phase detection pixel RPD is determined will be described later.

FIG. 3 is a cross-sectional view showing an embodiment of a cross section taken along the line XX′ in FIG. 2 .

The pixel array 100 may include a substrate layer 110 , a grid structure 120 , a color filter layer 130 and a lens layer 140 .

The substrate layer 110 may include a substrate 112 , photoelectric conversion regions 114 , and device isolation structures 116 . The substrate layer 110 may include a first surface and a second surface positioned opposite to the first surface. In this case, the first surface may represent a surface on which light is incident from the outside.

The substrate 112 may include a semiconductor substrate including single crystal silicon. The substrate 112 may include P-type impurities.

The photoelectric conversion regions 114 may be formed in the semiconductor substrate 112 to correspond to each unit pixel. The photoelectric conversion regions 114 may photoelectrically convert incident visible light filtered by the color filter layer 130 to generate photocharges. The photoelectric conversion regions 114 may include N-type impurities.

The device isolation structure 116 may be formed between the photoelectric conversion regions 114 of adjacent unit pixels in the substrate 112 to isolate the photoelectric conversion regions 114 . The device isolation structure 116 may include a trench structure such as Back Deep Trench Isolation (BDTI) or Front Deep Trench Isolation (FDTI). Alternatively, the device isolation structure 116 may include a junction isolation structure in which high-concentration impurities (eg, P-type impurities) are implanted into the substrate 112 .

The grid structure 120 may be positioned between color filters of adjacent unit pixels to prevent crosstalk between color filters. The grid structure 120 may be formed on the first surface of the substrate layer 110 . The grid structure 120 may include a first grid structure 120a and a second grid structure 120b.

The first grid structure 120a is formed between the color filters of the image pixels PX_R, PX_G, and PX_B and between the color filters of the image pixels PX_R, PX_G, and PX_B and the color filters of the phase detection pixels LPD and RPD. can be located in between. The first grid structure 120a includes a barrier metal layer 122a, a metal layer 124 positioned on the barrier metal layer 122a, and a capping film covering the barrier metal layer 122a and the metal layer 124 ( 126) may be included. The barrier metal layer 122a may include any one of Ti and TiN or a structure in which they are stacked, and the metal layer 124 may include tungsten. The capping layer 126 may include a nitride layer and cover the barrier metal layer 122a and the metal layer 124 and extend to an area under the color filter layer 130 . The capping layer 126 may prevent the expansion of the metal layer 124 during the heat treatment process. A region formed under the color filter layer 130 in the capping layer 126 may be used as a part of the antireflection layer.

The second grid structure 120b may be positioned between the color filters of the first phase detection pixels LPD and the color filters of the second phase detection pixels RPD. The second grid structure 120b may include a barrier metal layer 122b and a capping layer 126 covering the barrier metal layer 122b. Compared to the first grid structure 120a, the second grid structure 120b does not have a metal layer formed on the barrier metal layer 122b. The barrier metal layer 122b may include the same material as the barrier metal layer 122a.

In this embodiment, the case where the metal layer 124 is positioned on the barrier metal layer 122a in the first grid structure 120a has been described, but instead of the metal layer 124, an air layer and a low refractive index material are used. A layer or an oxide film layer or the like may be formed.

The color filter layer 130 may include color filters that filter visible light from light incident through the lens layer 140 . The color filter layer 130 includes red color filters that pass visible light of red color in a first wavelength band, green color filters that pass visible light of green color of a second wavelength band shorter than the first wavelength band, and a second wavelength band. It may include blue color filters that pass visible light of a blue color of a shorter third wavelength band. In adjacently positioned unit pixels of the same color, one color filter may be formed to cover the entire unit pixels.

The lens layer 140 may include an overcoating layer 142 and microlenses 144 . An overcoating layer 142 may be formed on the color filter layer 130 . The overcoating layer 142 may serve as a planarization layer to compensate for a level difference that may be generated by the color filter layer 130 . The microlenses 144 may be formed on the overcoating layer 142, and may condense incident light and pass it to a corresponding color filter. Each of the microlenses 144 may be formed in a hemispherical shape. One microlens is formed on each of the image pixels PX_R, PX_G, and PX_B, and one microlens is formed on the phase detection pixels LPD and RPD, and the color filters of the two phase detection pixels LPD and RPD are formed. It can be formed to cover all. The over-coating layer 142 and the micro lenses 144 may be formed of the same material.

In order to improve shading variations, the microlenses 144, color filters 130, and grid structures 120 correspond to image pixels PX_R, PX_G, PX_B or phase detection pixels ( Depending on the position of the LPD and RPD in the pixel array 100, they may be shifted by a predetermined interval to correspond to a chief ray angle (CRA). For example, the microlenses 144 and the color filters 130 may be shifted outward by a predetermined interval corresponding to the CRA of the corresponding unit pixel without being aligned with the photoelectric conversion element 114. The grid structures 120 may not be aligned with the device isolation structure 116 and may be shifted correspondingly to the CRA of corresponding unit pixels.

In this embodiment, the second grid structure 120b positioned between the phase detection pixels LPD and RPD is not shifted to correspond to the CRA of the corresponding phase detection pixels LPD and RPD, but a certain area around the second grid structure 120b. Based on the optical characteristics (eg, light sensitivity) of the other phase detection pixels LPD and RPD and the image pixels PX_G having the same color filter as the phase detection pixels LPD and RPD. so that it can be shifted. That is, the second grid structure 120b may be shifted by a different distance from the first grid structure 120a.

Preferably, a pair of adjacent phase detection pixels LPD and RPD have the same light sensitivity. In addition, it is preferable that the light sensitivity of each of the phase detection pixels LPD and RPD is the same as that of the image pixels of the same color in the vicinity thereof. To this end, in this embodiment, the pixel array 100 is divided into a plurality of sub-pixel areas based on the arrangement structure of the phase detection pixels LPD and RPD, and the phase detection pixels LPD in each sub-pixel area , RPD) and the light sensitivity (signal value) of the image pixels PX_G, the degree of shift of the second grid structures 120b within the corresponding area is determined.

4 is a flowchart exemplarily illustrating a method of determining a location of a second grid structure positioned between phase detection pixels. FIG. 5 is a diagram exemplarily showing a phase detection pixel array to be formed within the pixel array of FIG. 1 , and FIG. 6 is a diagram exemplarily showing how the pixel array of FIG. 5 is divided into a plurality of sub-pixel regions. FIG. 7 is a diagram exemplarily showing how to move the location of a grid structure between phase detection pixels, and FIG. 8 is a diagram showing an example of a range in which the location of a grid structure can be moved.

The phase detection pixels LPD and RPD may be continuously arranged at regular intervals in the X and Y directions within the pixel array 100 . For example, as shown in FIG. 5 , in the pixel array 100, phase detection pixel pairs including adjacent phase detection pixels LPD and RPD are continuously arranged in H(=800)×V(=600). It may include a phase detection pixel array. The size of the phase detection pixel array may vary depending on the size (eg, number of pixels) of the pixel array 100 and may be predetermined.

The design system (not shown) may divide the pixel array 100 into a plurality of sub-pixel regions based on a predetermined size of the phase detection pixel array (step S100).

To this end, the design system (not shown) is a pixel based on a value obtained by dividing the number 800 of horizontal phase detection pixel pairs and the number 600 of vertical phase detection pixel pairs in the phase detection pixel array by a preset number, respectively. The array 100 can be divided into a plurality of sub-pixel regions. For example, the design system (not shown) divides the number 800 of horizontal phase detection pixel pairs and the number 600 of vertical phase detection pixel pairs by 16, respectively, so as in FIG. 6, the pixel array ( 100) may be divided into 500 (=800/16)×375 (=600/16) sub-pixel areas {R(1,1) to R(500,375)}.

Each of the divided sub-pixel regions {R(1,1) to R(500,375)} may include a plurality of phase detection pixel pairs and a plurality of image pixels PX_G.

Next, the design system (not shown) determines the first phase detection pixels LPD, the second phase detection pixels RPD, and the image pixels PX_G included in the sub-pixel region for each sub-pixel region. An average value of the signal values is calculated (step S200).

For example, the design system (not shown) first determines the second grid structure 120b between the phase detection pixels LPD and RPD, as well as the grid structures 120a between the image pixels PX_R, PX_G and PX_B. Signal values of the first phase detection pixels (LPD), signal values of the second phase detection pixels (RPD), and signal values of the image pixels (PX_G) obtained by photographing in a state formed to correspond to the CRA as shown in FIG. Average values (LPDaver, RPDaver, PX_Gaver) for can be calculated.

Next, the design system (not shown) determines the first phase detection pixels LPD and the second phase detection pixels LPD for each sub-pixel region using the average values LPDaver, RPDaver, and PX_Gaver for each sub-pixel region obtained in step S200. Sensitivity values LPDsens and RPDsens of the detection pixels RPD are calculated (step S300).

For example, the design system (not shown) divides the signal average value LPDaver for the first phase detection pixels LPD by the signal average value PX_Gaver for the image pixels PX_G, so that the first phase detection pixels ( The second phase detection pixel is obtained by calculating the sensitivity value LPDsens for the LPD and dividing the average signal value RPDaver for the second phase detection pixels RPD by the average signal value PX_Gaver for the image pixels PX_G. A sensitivity value LPDsens for the RPD may be calculated.

Next, the design system (not shown) compares the sensitivity values LPDsens and RPDsens of the first phase detection pixels LPD and the second phase detection pixels RPD for each sub-pixel region to obtain two values ( It is determined whether the LPDsens and RPDsens match (or the difference between the two values LPDsens and RPDsens is within a preset range) (step S400).

As a result of the comparison, if the two values match (or the difference between the two values exists within a preset range), the design system (not shown) determines the location of the second grid structure 120b with respect to the corresponding sub-pixel area as the current location. Do (step S500).

On the other hand, when the two values do not match (or the difference between the two values exists within a preset range), the design system (not shown) determines the second grid structures 120b of the corresponding sub-pixel area, as shown in FIG. 7 . ), the above steps S200 to S400 may be performed again while changing the position.

When changing the position of the second grid structure 120b, the design system (not shown) may change the second grid structure 120b within a range that does not exceed the center line of the phase detection pixels LPD and RPD. . For example, the design system (not shown) may change the position of the second grid structure 120b only within a region between lines marked '1/4' and '3/4' in FIG. 8 .

In the above-described embodiment, '16' is used as a denominator value for dividing the pixel array 100 into a plurality of sub-pixel regions {R(1,1) to R(500,375)}, but is not limited thereto. For example, if the denominator value is too small, the number of pixels included in each sub-pixel area increases and the amount of calculation in step S200 may become too large. It can be set to any value in between.

The process of FIG. 4 described above may be performed for each sub-pixel area for all sub-pixel areas (R(1,1) to R(500,375)) in the pixel array 100 . Accordingly, the second grid structures 120b may be shifted differently for each sub-pixel area, and within the same sub-pixel area, all of the second grid structures 120b may be shifted by the same distance.

FIG. 9 is a cross-sectional view showing another embodiment of a cross section taken along the line XX′ in FIG. 2 .

In this embodiment, compared to the above-described structure of FIG. 3, a description of the same configuration will be omitted, and a structure with a difference will be mainly described.

Referring to FIG. 9 , a grid structure 120' may include a first grid structure 120a and a second grid structure 120c.

The first grid structure 120a is formed between the color filters of the image pixels PX_R, PX_G, and PX_B and between the color filters of the image pixels PX_R, PX_G, and PX_B and the color filters of the phase detection pixels LPD and RPD. can be located in between. The first grid structure 120a may have the same structure as the grid structure 120a in FIG. 3 .

The second grid structure 120c may be positioned between color filters of the phase detection pixels LPD and RPD. The second grid structure 120c may include a barrier metal layer 122c and a capping layer 126 covering the barrier metal layer 122c.

Compared to the first grid structure 120a, the second grid structure 120c does not have a metal layer formed on the barrier metal layer 122c. Also, the second grid structure 120c may have a different width from that of the first grid structure 120a.

For example, the first grid structure 120a may be shifted to correspond to the CRA of corresponding image pixels IPX and may be formed to have the same width as the entire pixel array 100 . On the other hand, the second grid structure 120c is shifted to correspond to the CRA of the phase detection pixels LPD and RPD, but its width is within a certain area (sub-pixel area) of the other phase detection pixels LPD, RPD) and the image pixels PX_G of the same color as the phase detection pixels LPD and RPD may be differently formed based on optical characteristics (eg, light sensitivity). That is, the second grid structure 120c may be formed to have a different width according to its formation position in the pixel array.

At this time, in the method of determining the width of the second grid structure 120c, in step S400 of FIG. 4 described above, the two sensitivity values LPDsens and RPDsens match (or the difference between the two sensitivity values exists within a preset range). ), the same method as that of FIG. 4 may be used except that the widths of the second grid structures 120c in the corresponding sub-pixel area are adjusted as shown in FIG. 10 .

When the width of the second grid structure 120c is adjusted, the design system (not shown) determines the average value LPDaver of the first phase detection pixels LPD and the average value RPDaver of the second phase detection pixels RPD. The average value (LPDaver) of the first phase detection pixels (LPD) and the average value (RPDaver) of the second phase detection pixels (RPD) while being equal to or more than 1/2 of the average value (PX_Gaver) of the image pixels (PX_G) The average of the image pixels PX_G may not exceed 1.2 times the average value PX_Gaver.

Alternatively, the width of the second grid structure 120c may not exceed the width of the device isolation structure 116 . For example, the width of the second grid structure 120c may be smaller than or equal to the width of the device isolation structure 116 positioned between the photoelectric conversion regions 114 of the corresponding phase detection pixels LPD and RPD. can

In this embodiment, width adjustment of the second grid structures 120c may be performed for each sub-pixel area for all sub-pixel areas (R(1,1) to R(500,375)) in the pixel array 100. there is. Accordingly, the second grid structures 120c may have different widths for each sub-pixel area, and all second grid structures 120b may have the same width within the same sub-pixel area.

FIG. 11 is a diagram showing a planar structure of a portion of the pixel array in FIG. 1 as an example.

In this embodiment, compared to the above-described structure of FIG. 2, description of the same configuration will be omitted, and a structure with a difference will be mainly described.

Referring to FIG. 11 , the pixel array 100 may include a plurality of unit pixels continuously arranged in a row direction and a column direction. The plurality of unit pixels may include a plurality of image pixels IPX and a plurality of phase detection pixels PDPX′.

The phase detection pixels PDPX' may be positioned between the image pixels IPX, and a pair of phase detection pixels disposed adjacently in the vertical and horizontal directions so as to detect phase differences in both the horizontal and vertical directions. It may include pixels LPD1 , RPD1 , LPD2 , and RPD2 . The pair of phase detection pixels PDPX′ may be continuously arranged at regular intervals in the X and Y directions in an array form.

The phase detection pixels LPD1 , RPD1 , LPD2 , and RPD2 may include color filters of the same color. For example, the phase detection pixels LPD1 , RPD1 , LPD2 , and RPD2 may include a green color filter.

In the case of this embodiment, in step S200 of FIG. 4 described above, the design system (not shown) first phase detection pixels LPD1 included in the corresponding sub-pixel region for each sub-pixel region, and the second phase detection pixels ( RPD1), the average value of signal values for the third phase detection pixels LPD2, the fourth phase detection pixels RPD2, and the image pixels PX_G may be calculated.

In addition, in step S300 of FIG. 4 , the design system (not shown) converts the average signal values of the first to fourth phase detection pixels LPD1 , RPD1 , LPD2 , and RPD2 into signal average values of the image pixels PX_G, respectively. By dividing by , sensitivity values for the first to fourth phase detection pixels LPD1 , RPD1 , LPD2 , and RPD2 may be calculated respectively.

In addition, the design system (not shown) compares the sensitivity values of the first to fourth phase detection pixels LPD1 , RPD1 , LPD2 , and RPD2 to determine the first to fourth phase detection pixels LPD1 , RPD1 , LPD2 , The position and width of the second grid structure between the phase detection pixels LPD1 , RPD1 , LPD2 , and RPD2 may be determined so that the sensitivity values for RPD2 are identical to each other or a difference between the sensitivity values is within a preset range.

12A and 12B are diagrams illustratively illustrating appearances of microlenses formed on unit pixels in a partial area including phase detection pixels in FIG. 11 .

As shown in FIG. 12A, in the pixel array 100, one microlens IPXML may be formed for each image pixel in the image pixels IPX, and two phase detection pixels adjacent to the phase detection pixels PDPX′ may be formed. One microlens PDML1 may be formed for each of the pixels LPD1 and RPD1 (LPD2 and RPD2).

Alternatively, as shown in FIG. 12B, one microlens IPXML may be formed for each image pixel in the image pixels IPX, and four phase detection pixels LPD1 adjacent to the phase detection pixels PDPX′. , RPD1, LPD2, and RPD2, one microlens PDML2 may be formed to cover all of the color filters.

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: pixel array
110: substrate layer
120a: first grid structure
120b, 120c: second grid structure
130: color filter layer
140: lens layer
200: low driver
300: correlated double sampler
400: analog-to-digital converter
500: output buffer
600: column driver
700: timing controller

Claims (17)

a pixel array in which image pixels and phase detection pixel pairs are arranged so that phase detection pixel pairs in which a plurality of phase detection pixels are adjacently disposed are located between image pixels;
The pixel array is
photoelectric conversion regions formed in a substrate to correspond to the image pixels and the phase detection pixels;
device isolation structures positioned between adjacent photoelectric conversion regions in the substrate;
color filters positioned on the substrate to correspond to the image pixels and the phase detection pixel pairs;
A first image pixel and a first phase detection pixel pair located adjacent to each other among the image pixels and the phase detection pixel pairs are located between color filters, a first grid structure shifted by a first distance from an element isolation structure positioned between the photoelectric conversion regions of the detection pixel pair; and
a second grid structure positioned on the color filter of the first phase detection pixel pair and shifted by a second distance different from the first distance from an element isolation structure positioned between photoelectric conversion regions of the first phase detection pixel pair; Image sensing device comprising a. The method of claim 1,
The first grid structure is formed such that a capping layer covers a stacked structure of a first material layer and a second material layer,
The second grid structure is formed such that the capping layer covers a single layer structure on which the second material layer is not formed on the first material layer. The method according to claim 2, wherein the first material layer
An image sensing device comprising any one of Ti and TiN. The method according to claim 3, wherein the second material layer
An image sensing device comprising any one of metal, air and insulator. The method according to claim 1, wherein each of the phase detection pixel pairs
An image sensing device comprising two phase detection pixels or four phase detection pixels arranged adjacently. The method according to claim 1, wherein the second grid structure
The image sensing device according to claim 1 , wherein the size of the second distance is formed differently based on the position of the corresponding phase detection pixel pair in the pixel array. The method of claim 6,
the pixel array is divided into a plurality of sub-pixel regions each including a certain number of pairs of the phase detection pixels;
The image sensing device of claim 1 , wherein the second grid structure has a different size of the second distance for each sub-pixel area. The method of claim 7,
The image sensing device of claim 1 , wherein all of the second grid structures in the same sub-pixel area are shifted by the same distance. a pixel array in which image pixels and phase detection pixel pairs are arranged so that phase detection pixel pairs in which a plurality of phase detection pixels are adjacently disposed are located between image pixels;
The pixel array is
a first grid structure positioned between the image pixels and between the image pixel and the phase detection pixel pair; and
A second grid structure positioned between the plurality of phase detection pixels;
The image sensing device of claim 1 , wherein the second grid structure is formed to have a different width from that of the first grid structure. The method of claim 9,
The first grid structure is formed such that a capping layer covers a stacked structure of a first material layer and a second material layer,
The second grid structure is formed such that the capping layer covers a single layer structure on which the second material layer is not formed on the first material layer. The method according to claim 10, wherein the first material layer
An image sensing device comprising any one of Ti and TiN. The method according to claim 11, wherein the second material film layer
An image sensing device comprising any one of metal, air and insulator. 10. The method of claim 9, wherein each of the phase detection pixel pairs
An image sensing device comprising two phase detection pixels or four phase detection pixels arranged adjacently. The method of claim 9,
The image sensing device of claim 1 , wherein the second grid structure is formed to have different widths based on positions of corresponding phase detection pixel pairs in the pixel array. The method of claim 14,
the pixel array is divided into a plurality of sub-pixel regions each including a certain number of pairs of the phase detection pixels;
The image sensing device of claim 1 , wherein the second grid structure has a different width in units of the sub-pixel area. The method of claim 15
The image sensing device of claim 1 , wherein all of the second grid structures in the same sub-pixel area have the same width. The method according to claim 9, wherein the second grid structure
The image sensing device according to claim 1 , wherein the width of the device isolation structure positioned between the photoelectric conversion regions of the plurality of phase detection pixels is smaller than or equal to the width of the device isolation structure.

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