Image sensing device

Abstract

The image sensing device includes a pixel array, and the pixel array includes a plurality of image sensing pixels and phase detection pixel pairs. The phase detection pixel pairs are disposed between the image sensing pixels and include phase detection pixels. The pixel array includes: a plurality of photoelectric conversion regions corresponding to the image sensing pixels and the phase detection pixels; a plurality of device isolation structures that isolate the photoelectric conversion regions from each other; a plurality of color filters corresponding to the image sensing pixels and the phase detection pixel pairs; a first grid structure disposed between the color filter of a first image sensing pixel and the color filter of an adjacent first phase detection pixel pair and offset from a first device isolation structure by a first distance, the first device isolation structure being disposed between the first image sensing pixel and the first phase detection pixel pair; and a second grid structure disposed in the color filter of the first phase detection pixel pair and offset from a second device isolation structure by a second distance, the second device isolation structure being disposed between the first phase detection pixel pair.

Description

Technical Field

[0001] The technologies and implementations disclosed in this patent document generally relate to an image sensing device including phase detection pixels. Background Art

[0002] Image sensing devices are used in electronic devices to convert optical images into electrical signals. With the latest developments in the automotive, medical, computer, and communication industries, the demand for highly integrated and higher-performance image sensors in various electronic devices (e.g., digital cameras, video cameras, personal communication systems (PCS), video game consoles, surveillance cameras, medical micro cameras, and robots) has increased rapidly. Summary of the Invention

[0003] Various embodiments of the disclosed technologies relate to an image sensing device capable of improving phase detection characteristics.

[0004] According to one embodiment of the disclosed technology, an image sensing device may include a pixel array including a plurality of image sensing pixels and phase detection pixel pairs. The phase detection pixel pairs are disposed between the image sensing pixels and include phase detection pixels. The pixel array may include: a plurality of photoelectric conversion regions formed in a substrate corresponding to the image sensing pixels and the phase detection pixels; a plurality of device isolation structures disposed in the substrate to isolate the photoelectric conversion regions from each other; a plurality of color filters disposed above the substrate corresponding to the image sensing pixels and the phase detection pixel pairs; a first grid structure disposed between a color filter of a first image sensing pixel among the plurality of image sensing pixels and a color filter of a first phase detection pixel pair adjacent to the first image sensing pixel among the phase detection pixel pairs and offset from a first device isolation structure by a first distance, the first device isolation structure being disposed between a photoelectric conversion region of the first image sensing pixel and a photoelectric conversion region of the first phase detection pixel pair; and a second grid structure disposed in the color filter of the first phase detection pixel pair and offset from a second device isolation structure by a second distance different from the first distance, the second device isolation structure being disposed between the photoelectric conversion regions of the first phase detection pixel pair.

[0005] According to another embodiment of the disclosed technology, an image sensing device may include a pixel array that includes a plurality of image sensing pixels and pairs of phase detection pixels. The pairs of phase detection pixels are disposed between the image sensing pixels and include a plurality of phase detection pixels. The pixel array may include: a plurality of first grid structures that are disposed between the image sensing pixels and between the image sensing pixels and the pairs of phase detection pixels; and a plurality of second grid structures that are disposed between the plurality of phase detection pixels. The second grid structures may have a different width from the first grid structures.

[0006] It should be understood that the foregoing general description and the following detailed description of the disclosed technology are both illustrative and explanatory and are intended to provide further explanation of the claimed disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a block diagram showing an example of an image sensing device based on some implementations of the disclosed technology.

[0008] Figure 2 is a plan view showing an example of the pixel array shown based on one embodiment of the disclosed technology Figure 1 as shown.

[0009] Figure 3 is a cross-sectional view showing an example of the pixel array taken along line X-X' shown based on some implementations of the disclosed technology Figure 2 as shown.

[0010] Figure 4 is a flowchart showing an example of a method for determining the position of a second grid structure disposed between phase detection pixels based on some implementations of the disclosed technology.

[0011] Figure 5 is a schematic diagram showing an example of a phase detection pixel array to be formed in the pixel array shown based on some implementations of the disclosed technology Figure 1 as shown.

[0012] Figure 6 is a schematic diagram showing an example structure in which the pixel array shown based on some implementations of the disclosed technology is divided into a plurality of sub-pixel regions Figure 5 as shown.

[0013] Figure 7 is a cross-sectional view showing an example structure in which the position of a grid structure disposed between phase detection pixels is offset based on some implementations of the disclosed technology.

[0014] Figure 8Is a cross-sectional view showing an example structure of the positional offset of the grid structure in some implementations based on the disclosed technology.

[0015] Figure 9 Is a cross-sectional view showing another example of a pixel array taken along the Figure 2 line X-X' shown.

[0016] Figure 10 Is a cross-sectional view showing an example structure in which the width of the grid structure provided between phase detection pixels is adjusted in some implementations based on the disclosed technology.

[0017] Figure 11 Is a plan view showing an example of the Figure 1 pixel array shown in one embodiment based on the disclosed technology.

[0018] Figure 12A and Figure 12B Is a view showing an example of a microlens formed in a unit pixel within a part of a region including the Figure 11 phase detection pixels shown in some implementations based on the disclosed technology. Detailed Description

[0019] This patent document provides implementations and examples of an image sensing device including phase detection pixels, and the disclosed features can be implemented to achieve one or more advantages in more applications. Some implementations of the disclosed technology propose a design of an image sensing device capable of improving phase detection characteristics. The disclosed technology provides various implementations of an image sensing device, which can improve the grid structure of phase detection pixels, thereby improving phase detection characteristics.

[0020] Now, certain embodiments will be described in detail, examples of which are shown in the drawings. Where possible, the same reference numerals will be used throughout the drawings to represent the same or similar parts. In the following description, detailed descriptions of related known configurations or functions incorporated herein will be omitted to avoid obscuring the subject matter.

[0021] Figure 1 Is a block diagram showing an image sensing device in some implementations based on the disclosed technology.

[0022] Referring to Figure 1 , the image sensing device may include a pixel array 100, a row driver 200, a correlated double sampler (CDS) 300, an analog-to-digital converter (ADC) 400, an output buffer 500, a column driver 600, and a timing controller 700. Figure 1The components of the image sensing device shown are discussed by way of example only, and this patent document includes many other changes, substitutions, variations, alterations, and modifications.

[0023] The pixel array 100 may include a plurality of unit pixels arranged in rows and columns. In one example, the plurality of unit pixels can be arranged in a two-dimensional (2D) pixel array including rows and columns. In another example, the plurality of unit pixels can be arranged in a three-dimensional (3D) pixel array. The plurality of unit pixels can convert an optical signal into an electrical signal based on a unit pixel or a pixel group, where the unit pixels in the pixel group share at least some internal circuits. The plurality of unit pixels can include a plurality of image sensing pixels and a plurality of phase detection pixels. Each image sensing pixel can generate an image signal as an electrical signal corresponding to a target object to be captured. Each phase detection pixel can generate a phase signal as an electrical signal for calculating a phase difference between images captured by the image sensing pixels.

[0024] The pixel array 100 can receive drive signals (e.g., row selection signals, reset signals, transmit (or transfer) signals, etc.) from the row driver 200. Upon receiving the drive signals, the unit pixels can be activated to perform operations corresponding to the row selection signal, reset signal, and transfer signal.

[0025] The row driver 200 can activate the pixel array 100 based on control signals provided by a controller circuit such as the timing controller 700 to perform certain operations on the unit pixels in the corresponding row. In some implementations, the row driver 200 can select one or more pixel groups arranged in one or more rows of the pixel array 100. The row driver 200 can generate a row selection signal to select one or more rows from the plurality of rows. The row driver 200 can sequentially enable the reset signal and the transfer signal for the unit pixels arranged in the selected rows. The pixel signals generated by the unit pixels arranged in the selected rows can be output to the correlated double sampler (CDS) 300.

[0026] The correlated double sampler (CDS) 300 can use correlated double sampling to remove the undesired offset values of a unit pixel. In one example, the correlated double sampler (CDS) 300 can remove the undesired offset values of a unit pixel by comparing the output voltages of the pixel signals (of the unit pixel) obtained before and after the optical charge generated by the incident light accumulates in the sensing node (i.e., the floating diffusion (FD) node). As a result, the CDS 300 can obtain the pixel signal generated only by the incident light without introducing noise. In some implementations, when receiving a clock signal from the timing controller 700, the CDS 300 can sequentially sample and hold the voltage levels of the reference signal and the pixel signal provided to each of the multiple column lines from the pixel array 100. That is, the CDS 300 can sample and hold the voltage levels of the reference signal and the pixel signal corresponding to each column of the pixel array 100. In some implementations, the CDS 300 can transmit the pixel signal and the reference signal of each column as a correlated double sampling (CDS) signal to the ADC 400 based on a control signal from the timing controller 700.

[0027] The ADC 400 is used to convert the analog CDS signal received from the CDS 300 into a digital signal. In some implementations, the ADC 400 can be implemented as a ramp comparison type ADC. The analog-to-digital converter (ADC) 400 can compare the ramp signal received from the timing controller 700 with the CDS signal received from the CDS 300, and thereby can output a comparison signal indicating the comparison result between the ramp signal and the CDS signal. The analog-to-digital converter (ADC) 400 can count the level transition time of the comparison signal in response to the ramp signal received from the timing controller 700, and can output a count value indicating the counted level transition time to the output buffer 500.

[0028] The output buffer 500 can temporarily store the column-based image data provided from the ADC 400 based on the control signal of the timing controller 170. The image data received from the ADC 400 can be temporarily stored in the output buffer 500 based on the control signal of the timing controller 700. The output buffer 500 can provide an interface to compensate for the data rate difference or the transmission rate difference between the image sensing device and other devices.

[0029] The column driver 600 can select columns of the output buffer 500 when receiving a control signal from the timing controller 700, and sequentially output the image data temporarily stored in the selected columns of the output buffer 500. In some implementations, when receiving an address signal from the timing controller 700, the column driver 600 can generate a column selection signal based on the address signal, can select columns of the output buffer 500 using the column selection signal, and can control the image data received from the selected columns of the output buffer 500 to be output as an output signal.

[0030] The timing controller 700 can generate signals for controlling the operations of the row driver 200, the ADC 400, the output buffer 500, and the column driver 600. The timing controller 700 can provide a clock signal, a control signal for timing control, and an address signal for selecting a row or a column required for the operations of the respective components of the image sensing device to the row driver 200, the column driver 600, the ADC 400, and the output buffer 500. In some implementations, the timing controller 700 can include a logic control circuit, a phase-locked loop (PLL) circuit, a timing control circuit, a communication interface circuit, and the like.

[0031] Figure 2 is a plan view showing an example of the Figure 1 pixel array 100 according to an embodiment of the disclosed technology.

[0032] Referring to Figure 2 , the pixel array 100 can include a plurality of unit pixels arranged continuously in the row and column directions. The plurality of unit pixels can include a plurality of image sensing pixels (IPX) and a plurality of phase detection pixel pairs (PDPX).

[0033] The plurality of image sensing pixels (IPX) can detect incident light to generate an image signal corresponding to an image of a target object in the incident light. The plurality of image sensing pixels (IPX) can include a red pixel (PX_R) for generating an image signal corresponding to red light, a green pixel (PX_G) for generating an image signal corresponding to green light, and a blue pixel (PX_B) for generating an image signal corresponding to blue light.

[0034] Each image sensing pixel (IPX) may include unit pixels arranged in an (N×N) array and including color filters of the same color (where "N" is a natural number of 2 or greater). In some implementations, a red pixel (PX_R) includes a photoelectric conversion element covered by a red color filter, a green pixel (PX_G) includes a photoelectric conversion element covered by a green color filter, and a blue pixel (PX_B) includes a photoelectric conversion element covered by a blue color filter. In some implementations, the image sensing pixel (IPX) may include a red sub-pixel block, a green sub-pixel block, and a blue sub-pixel block, each red sub-pixel block having a structure in which four red pixels (PX_R) are arranged in a (2×2) array, each green sub-pixel block having a structure in which four green pixels (PX_G) are arranged in a (2×2) array, and each blue sub-pixel block having a structure in which four blue pixels (PX_B) are arranged in a (2×2) array. The pixel array 100 may include a quaternary structure in which the red sub-pixel block, the green sub-pixel block, and the blue sub-pixel block are arranged in a Bayer pattern.

[0035] Phase detection pixel pairs (PDPX) may be provided between the image sensing pixels (IPX) to generate phase signals for calculating the phase difference between images formed by capturing an image of a target object. A plurality of phase detection pixel pairs (PDPX) may include two phase detection pixels adjacent to each other in a first direction (X-axis direction) or a second direction (Y-axis direction). For example, each phase detection pixel pair (PDPX) may include a first phase detection pixel (LPD) and a second phase detection pixel (RPD) adjacent to each other in the first direction, as Figure 2 shown.

[0036] Although Figure 2 the first phase detection pixel LPD and the second phase detection pixel RPD shown are adjacent to each other in the first direction (X direction), the first phase detection pixel LPD and the second phase detection pixel RPD may also be adjacent to each other in the second direction (Y direction). In other implementations, each phase detection pixel pair (PDPX) may include four phase detection pixels adjacent to each other in the first direction and the second direction to detect the phase difference in both the first direction and the second direction.

[0037] The first phase detection pixel LPD and the second phase detection pixel RPD included in each phase detection pixel pair (PDPX) may include color filters of the same color. For example, as Figure 2 shown, the first phase detection pixel LPD and the second phase detection pixel RPD may include green color filters. Although Figure 2One color filter is shown for each unit pixel (for each image sensing pixel or for each phase detection pixel). However, it should be noted that when unit pixels of the same color are arranged adjacent to each other, only one color filter is formed across the corresponding unit pixels.

[0038] The first phase detection pixels LPD and the second phase detection pixels RPD formed as an array may be continuously formed at regular intervals in a first direction and a second direction.

[0039] In the pixel array 100, a grid structure for preventing crosstalk between adjacent color filters may be formed between the color filters of the unit pixels. In this case, the grid structure provided between the first phase detection pixels LPD and the second phase detection pixels RPD may be structurally different from the grid structure provided between the image sensing pixels (IPX), and may also be structurally different from the grid structure provided between the image sensing pixels (IPX) and the phase detection pixels LPD or RPD. In addition, the position and width of the grid structure provided between the first phase detection pixels LPD and the second phase detection pixels RPD may be determined based on the sensitivities of other phase detection pixels surrounding the corresponding phase detection pixel and the sensitivities of the image sensing pixels surrounding the corresponding phase detection pixel and having the same color filter as the color filter of the corresponding phase detection pixel. The position and width of the grid structure provided between the first phase detection pixels LPD and the second phase detection pixels RPD may be determined as described below.

[0040] Figure 3 is a cross-sectional view showing an example of the pixel array 100 taken along the line X-X’ shown based on some implementations of the disclosed technology. Figure 2 as shown.

[0041] Referring to Figure 3 , the pixel array 100 may include a substrate layer 110, a grid structure 120, a color filter layer 130, and a lens layer 140.

[0042] The substrate layer 110 may include a substrate 112, a plurality of photoelectric conversion regions 114, and a plurality of device isolation structures 116. The substrate layer 110 may include a first surface and a second surface opposite or contrary to the first surface. In this case, the first surface may refer to the light receiving surface on which light is incident.

[0043] The substrate 112 may include a semiconductor substrate containing a single crystal silicon material. The substrate 112 may include P-type impurities.

[0044] The photoelectric conversion region 114 may be formed in the semiconductor substrate 112, and each photoelectric conversion region 114 can correspond to a unit pixel. The photoelectric conversion region 114 may perform photoelectric conversion of incident light (e.g., visible light) filtered by the color filter layer 130 to generate photo charges carrying an image in the incident light. Each photoelectric conversion region 114 may include N-type impurities.

[0045] Each device isolation structure 116 may be formed between the photoelectric conversion regions 114 of adjacent unit pixels within the substrate 112 to isolate the photoelectric conversion regions 114 from each other. The device isolation structure 116 may include a trench structure, such as a backside deep trench isolation (BDTI) structure or a front side deep trench isolation (FDTI) structure. Alternatively, the device isolation structure 116 may include a junction isolation structure formed by implanting high-density impurities (e.g., P-type impurities) into the substrate 112.

[0046] The grid structure 120 may be disposed between the color filters of adjacent unit pixels to prevent crosstalk between adjacent color filters. The grid structure 120 may be formed above 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.

[0047] The first grid structure 120a may be disposed between the color filters of the image sensing pixels PX_R, PX_G, and PX_B, and may also be disposed between the color filters of the image sensing pixels PX_R, PX_G, and PX_B and the color filters of the phase detection pixels LPD and RPD. The first grid structure 120a may include a blocking metal layer 122a, a metal layer 124 disposed above the blocking metal layer 122a, and a capping layer 126 covering the metal layer 124 and the blocking metal layer 122a. The blocking metal layer 122a may include titanium (Ti) or titanium nitride (TiN) or a combination of titanium (Ti) and titanium nitride (TiN) (e.g., its stacked structure). The metal layer 124 may include tungsten (W). The capping layer 126 may include a nitride layer and may be formed to extend under the color filter layer 130 while covering the blocking metal layer 122a and the metal layer 124. The capping layer 126 may prevent the metal layer 124 from expanding in a thermal annealing process. In the capping layer 126, the region formed under the color filter layer 130 may be used as part of an antireflection layer.

[0048] The second grid structure 120b may be disposed between the color filter of the first phase detection pixel LPD and the color filter of the second phase detection pixel RPD. The second grid structure 120b may include a blocking metal layer 122b and a capping layer 126 covering the blocking metal layer 122b. Different from the first grid structure 120a, in the second grid structure 120b, a metal layer may not be formed above the blocking metal layer 122b. The blocking metal layer 122b may include the same material as the blocking metal layer 122a.

[0049] Although Figure 3 it is shown by way of example that the metal layer 124 is disposed above the blocking metal layer 122a in the first grid structure 120a, it should be noted that in addition to or instead of the metal layer 124, different material layers (e.g., an air layer, a low refractive index material layer, or an oxide layer) can also be formed.

[0050] The color filter layer 130 may include color filters that filter visible light in a specific wavelength range from the incident light received through the lens layer 140 and transmit the filtered light to the corresponding photoelectric conversion region 114. The color filter layer 130 may include a plurality of red color filters, a plurality of green color filters, and a plurality of blue color filters. Each red color filter may transmit visible light corresponding to a first wavelength band of red. Each green color filter may transmit visible light corresponding to a second wavelength band shorter than the first wavelength band of green. Each blue color filter may transmit visible light corresponding to a third wavelength band shorter than the second wavelength band of blue. Among adjacent same-color unit pixels, one color filter may cover two or more unit pixels. For example, one color filter may be formed across the corresponding unit pixels.

[0051] The lens layer 140 may include an over-coating layer 142 and a plurality of microlenses 144. The over-coating layer 142 may be formed above the color filter layer 130. The over-coating layer 142 may serve as a planarization layer capable of planarizing the uneven surface caused by the color filter layer 130. The microlenses 144 may be formed above the over-coating layer 142. Each microlens 144 may be formed in a hemispherical shape and may be formed by unit pixel (PX). The microlenses 144 may converge the incident light and transmit the converged light to the corresponding color filter. One microlens may be formed above each of the image sensing pixels PX_R, PX_G, and PX_B. One microlens may be formed to cover all the color filters of two phase detection pixels LPD and RPD. The over-coating layer 142 and the microlenses 144 may be formed of the same material.

[0052] To improve shading variation, according to the placement positions of image sensing pixels (PX_R, PX_G, PX_B) or phase detection pixels (LPD, RPD) in the pixel array 100, the microlenses 144, color filters 130, and grid structures 120 can be offset by a predetermined distance corresponding to the chief ray angle (CRA). For example, the microlenses 144 and color filters 130 can be offset outward by a predetermined distance corresponding to the CRA of the corresponding unit pixel, and the grid structure 120 can be offset by an offset distance corresponding to the CRA of the corresponding unit pixel without being aligned with the device isolation structure 116.

[0053] In some implementations, the second grid structure 120b disposed between the phase detection pixels LPD and RPD may not be offset to correspond to the CRA of the corresponding phase detection pixels LPD and RPD, but may be offset based on the optical characteristics (e.g., light sensitivity) of other phase detection pixels LPD and RPD located around the second grid structure 120b and the optical characteristics (e.g., light sensitivity) of image sensing pixels (PX_G) having the same color filter as the color filters of the phase detection pixels LPD and RPD. That is, the second grid structure 120b may be offset by a different distance compared to the first grid structure 120a.

[0054] In some implementations, a pair of adjacent phase detection pixels LPD and RPD may be formed to have the same light sensitivity. In some implementations, the light sensitivity of the phase detection pixels LPD and RPD is the same as the light sensitivity of the surrounding image sensing pixels having the same color filter as the phase detection pixels LPD and RPD. To this end, the pixel array 100 can be divided into multiple sub-pixel regions according to the layout structure of the phase detection pixels LPD and RPD. Based on the light sensitivity (signal values) of the phase detection pixels (LPD, RPD) and image sensing pixels PX_G included in each sub-pixel region, the offset degree of the second grid structure 120b placed in the corresponding region can be determined.

[0055] Figure 4 is a flowchart showing an example of a method for determining the position of a second grid structure disposed between phase detection pixels based on some implementations of the disclosed technology. Figure 5 is shown to be formed based on some implementations of the disclosed technology in Figure 1 is a schematic diagram showing an example of a phase detection pixel array to be formed in the pixel array shown. Figure 6 shows based on some implementations of the disclosed technology in which Figure 5 is a schematic diagram showing an example structure in which the pixel array shown is divided into multiple sub-pixel regions. Figure 7It is a cross-sectional view showing an example structure in which the position of a grid structure provided between phase detection pixels is offset based on some implementations of the disclosed technology. Figure 8 It is a cross-sectional view showing an example structure in which the position of a grid structure is offset based on some implementations of the disclosed technology.

[0056] Phase detection pixels LPD and RPD can be continuously arranged at regular intervals in the pixel array 100 in the X-axis and Y-axis directions. For example, as Figure 5 shown, the pixel array 100 may include a phase detection pixel array in which phase detection pixel pairs PDPX including adjacent phase detection pixels LPD and RPD are continuously arranged in a size of H(=800)×V(=600) (where H is the size in the first direction and V is the size in the second direction). The size of such a phase detection pixel array can vary according to the predetermined size (e.g., the number of pixels) of the pixel array 100 and can be determined in advance.

[0057] In S100, a design system (not shown) can divide the pixel array 100 into a plurality of sub-pixel regions based on the predetermined size of the phase detection pixel array.

[0058] To this end, based on a first value obtained when the number (800) of phase detection pixel pairs PDPX in the arrangement of the phase detection pixel array in the first direction is divided by a predetermined number, and based on a second value obtained when the number (600) of phase detection pixel pairs PDPX in the arrangement of the phase detection pixel array in the second direction is divided by a predetermined number, a design system (not shown) can divide the pixel array 100 into a plurality of sub-pixel regions. For example, a design system (not shown) can divide each of the number (800) of the first phase detection pixel pairs and the number (600) of the second phase detection pixel pairs by 16, so that the pixel array 100 can be divided into "500(=800 / 16)×375(=600 / 16)" sub-pixel regions R(1,1) to R(375,500), as Figure 6 shown.

[0059] Each of the divided sub-pixel regions R(1,1) to R(375,500) may include a plurality of phase detection pixel pairs PDPX and a plurality of image sensing pixels (PX_G).

[0060] Subsequently, in S200, a design system (not shown) can calculate the average value of the signal values of the first phase detection pixels (LPD) in each sub-pixel region, can calculate the average value of the signal values of the second phase detection pixels (RPD) in each sub-pixel region, and can calculate the average value of the signal values of the image sensing pixels (PX_G) in each sub-pixel region.

[0061] For example, a design system (not shown) may calculate the average value (LPDaver) of the signal values of the first phase detection pixels (LPDs), the average value (RPDaver) of the signal values of the second phase detection pixels (RPDs), and the average value (PX_Gaver) of the signal values of the image sensing pixels (PX_G) captured in the following case: The second grid structure 120b disposed between the phase detection pixels LPD and RPD is also formed in the same manner as the grid structure 120a disposed between the image sensing pixels PX_R, PX_G, and PX_B to correspond to the chief ray angle (CRA).

[0062] Subsequently, in S300, a design system (not shown) may calculate the sensitivity value (LPDsens) of the first phase detection pixels (LPDs) for each sub-pixel region using the average values LPDaver, RPDaver, and PX_Gaver of the corresponding sub-pixel regions, and may calculate the sensitivity value (RPDsens) of the second phase detection pixels (RPDs) for each sub-pixel region using the average values LPDaver, RPDaver, and PX_Gaver of the corresponding sub-pixel regions.

[0063] For example, a design system (not shown) may calculate the sensitivity value (LPDsens) of the first phase detection pixels (LPDs) by dividing the average value (LPDaver) of the signals of the first phase detection pixels (LPDs) by the average value (PX_Gaver) of the signals of the image sensing pixels (PX_G), and may calculate the sensitivity value (RPDsens) of the second phase detection pixels (RPDs) by dividing the average value (RPDaver) of the signals of the second phase detection pixels (RPDs) by the average value (PX_Gaver) of the signals of the image sensing pixels (PX_G).

[0064] Subsequently, in S400, a design system (not shown) may compare the sensitivity value (LPDsens) of the first phase detection pixels (LPDs) with the sensitivity value (RPDsens) of the second phase detection pixels (RPDs) for each sub-pixel region, and may determine whether the two values LPDsens and RPDsens are the same as each other (or may determine whether the difference between the two values LPDsens and RPDsens is within a predetermined range).

[0065] When the two values LPDsens and RPDsens are the same as each other in S400 (or when the difference between the two values is within a predetermined range), a design system (not shown) may determine in S500 that the position of the second grid structure 120b in the corresponding sub-pixel region is the current position.

[0066] Conversely, when the two values LPDsens and RPDsens are different from each other (or when the difference between the two values LPDsens and RPDsens is not within a predetermined range), the design system (not shown) can perform the above operations S200 to S400 again while changing the position of the second grid structure 120b in the corresponding sub-pixel region as shown in Figure 7 shown.

[0067] During the process of changing the position of the second grid structure 120b, the design system (not shown) can perform the positioning of the second grid structure 120b as long as each second grid structure 120b does not pass through the center lines of the phase detection pixels LPD and RPD. For example, the design system (not shown) can change the position of the second grid structure 120b only within the region between the first line marked with "1 / 4" and the second line marked with "3 / 4" as shown in Figure 8 shown.

[0068] In the above embodiment, "16" is used as the denominator value, and through this denominator value, the pixel array 100 is divided into a plurality of sub-pixel regions R(1, 1) to R(375, 500), and other implementations are also possible. For example, when the denominator value is too small, the number of pixels included in each sub-pixel region increases, and the number of calculations in S200 may increase excessively. Therefore, the denominator value can be set to any one of the values from 16 to 32 according to the size of the pixel array 100.

[0069] The above operations shown can be performed for each sub-pixel region among all the sub-pixel regions R(1, 1) to R(375, 500) included in the pixel array 100. Figure 4 shown. Therefore, the second grid structure 120b can be offset differently in units of sub-pixel regions, and can be offset by the same distance within the same sub-pixel region.

[0070] Figure 9 is a cross-sectional view showing another example of a pixel array taken along the line X-X' shown based on some implementations of the disclosed technology. Figure 2 shown. Figure 10 is a cross-sectional view showing an example structure in which the width of the grid structure provided between phase detection pixels is adjusted based on some implementations of the disclosed technology.

[0071] In some implementations, Figure 9 the material layers and structures shown can be similar or identical to Figure 3 the material layers and structures shown. Figure 9 Some of the material layers and structures shown can be different from Figure 3 the material layers and structures shown, as will be discussed below.

[0072] Reference Figure 9 The grid structure 120' may include a first grid structure 120a and a second grid structure 120c.

[0073] The first grid structure 120a may be disposed between color filters of the image sensing pixels PX_R, PX_G, and PX_B, and may also be disposed between color filters of the image sensing pixels PX_R, PX_G, and PX_B and color filters of the phase detection pixels LPD and RPD. Figure 9 The first grid structure 120a shown may be the same in structure as Figure 3 the grid structure 120a shown.

[0074] The second grid structure 120c may be disposed between color filters of the phase detection pixels LPD and RPD. The second grid structure 120c may include a blocking metal layer 122c and a capping layer 126 covering the blocking metal layer 122c.

[0075] Compared with the first grid structure 120a, in the second grid structure 120c, a metal layer may not be formed above the blocking metal layer 122c. In addition, the second grid structure 120c may have a different width from the first grid structure 120a.

[0076] For example, the first grid structure 120a may be offset in response to the CRA of the corresponding image sensing pixel (IPX). In this case, the first grid structure 120a may be formed to have the same width as each other in the pixel array 100. In contrast, the second grid structure 120c may be offset in response to the CRA of the phase detection pixels LPD and RPD, and based on the optical characteristics (e.g., light sensitivity) of other phase detection pixels LPD and RPD located around the corresponding phase detection pixel in a predetermined region (i.e., sub-pixel region) and the optical characteristics (e.g., light sensitivity) of image sensing pixels (PX_G) having the same color filter as the corresponding phase detection pixel and located around the corresponding phase detection pixel in the predetermined region, the second grid structure 120c may be formed to have different widths. That is, depending on the position of the second grid structure 120c in the pixel array 100, the second grid structure 120c may be formed to have different widths.

[0077] In this case, in addition to determining the width of the second grid structure 120c as shown in Figure 10 here, it is possible to use Figure 4The method of determining the width of the second grid structure 120c may include adjusting the width of each second grid structure 120c placed in the corresponding sub-pixel region when the two sensitivity values LPDsens and RPDsens are different from each other (or when the difference between the two sensitivity values LPDsens and RPDsens is within a predetermined range).

[0078] When adjusting the width of the second grid structure 120c, a design system (not shown) may adjust each of the average value (LPDaver) of the first phase detection pixels (LPD) and the average value (RPDaver) of the second phase detection pixels (RPD) to be equal to or greater than 1 / 2 of the average value (PX_Gaver) of the image sensing pixels (PX_G), and at the same time may adjust each of the average value (LPDaver) of the first phase detection pixels (LPD) and the average value (RPDaver) of the second phase detection pixels (RPD) to be equal to or less than a threshold value corresponding to 1.2 times the average value (PX_Gaver) of the image sensing pixels (PX_G).

[0079] Alternatively, the width of the second grid structure 120c may be formed not to exceed the width of the device isolation structure 116. For example, the width of the second grid structure 120c may be equal to or less than the width of the device isolation structure 116 provided between the photoelectric conversion regions 114 of the corresponding phase detection pixels LPD and RPD.

[0080] In some implementations, the operation of adjusting the width of each second grid structure 120c may be performed for each sub-pixel region associated with all sub-pixel regions R(1, 1) to R(375, 500) included in the pixel array 100. Therefore, the second grid structure 120c may be formed to have different widths in units of sub-pixel regions, and the second grid structure 120b may be formed to have the same width within the same sub-pixel region.

[0081] Figure 11 is a plan view showing an example of a pixel array based on one embodiment of the disclosed technology Figure 1 shown.

[0082] In some implementations, Figure 11 some features of Figure 2 shown may be similar to or the same as Figure 11 some features of Figure 2 shown, which will be discussed below.

[0083] Referring to Figure 11, the pixel array 100 may include a plurality of unit pixels arranged continuously in row and column directions. Here, the plurality of unit pixels may include a plurality of image sensing pixels (IPX) and a plurality of phase detection pixels (PDPX’).

[0084] Each phase detection pixel (PDPX’) may be disposed between image sensing pixels (IPX), and may include a set of phase detection pixels (LPD1, RPD1, LPD2, RPD2) arranged adjacent to each other in a second direction and a first direction of the pixel array, so as to be able to detect both the phase difference generated in the first direction and the phase difference generated in the second direction. A pair of phase detection pixels (PDPX’) formed in the array may be continuously arranged at regular intervals in the X-axis direction and the Y-axis direction.

[0085] The phase detection pixels LPD1, RPD1, LPD2, and RPD2 may include color filters of the same color. For example, each of the phase detection pixels LPD1, RPD1, LPD2, and RPD2 may include a green color filter.

[0086] In Figure 4 S200, a design system (not shown) may calculate the average value of the signal values of the first phase detection pixel (LPD1) of each sub-pixel region, may calculate the average value of the signal values of the second phase detection pixel (RPD1) of each sub-pixel region, may calculate the average value of the signal values of the third phase detection pixel (LPD2) of each sub-pixel region, may calculate the average value of the signal values of the fourth phase detection pixel (RPD2) of each sub-pixel region, and may calculate the average value of the signal values of the image sensing pixel (PX_G) of each sub-pixel region.

[0087] In Figure 4 S300, a design system (not shown) may calculate the sensitivity values of the first phase detection pixel to the fourth phase detection pixel (LPD1, RPD1, LPD2, RPD2) by dividing the average value of the signal values of each of the first phase detection pixel to the fourth phase detection pixel (LPD1, RPD1, LPD2, RPD2) by the average value of the signal values of the image sensing pixel (PX_G).

[0088] A design system (not shown) may compare the sensitivity values of the first phase detection pixel to the fourth phase detection pixel (LPD1, RPD1, LPD2, RPD2) with each other, and may determine the position and width of the second grid structure between the phase detection pixels (LPD1, RPD1, LPD2, RPD2) such that the sensitivity values of the first phase detection pixel to the fourth phase detection pixel (LPD1, RPD1, LPD2, RPD2) are the same as each other or the difference between the sensitivity values is within a predetermined range.

[0089] Figure 12A and Figure 12B is a diagram showing an example of a microlens formed in a unit pixel within a part of a region including the Figure 11 phase detection pixels shown.

[0090] Referring to Figure 12A , in the image sensing pixels (IPX) of the pixel array 100, a microlens (IPXML) can be formed above each image sensing pixel. In the phase detection pixels (PDPX’), a microlens (PDML1) can be formed for two adjacent phase detection pixels (LPD1, RPD1), and another microlens (PDML1) can also be formed for another two adjacent phase detection pixels LPD2 and RPD2.

[0091] Alternatively, referring to Figure 12B , in the image sensing pixels (IPX), a microlens (IPXML) can be formed above each image sensing pixel (IPX). In the phase detection pixels (PDPX’), a microlens (PDML2) can be formed to cover all color filters of four adjacent phase detection pixels LPD1, RPD1, LPD2, and RPD2.

[0092] In various implementations, an image sensing device based on some implementations of the disclosed technology can improve the grid structure of phase detection pixels, thereby improving phase detection characteristics.

[0093] Although multiple exemplary embodiments have been described, it should be understood that various variations or enhancements and other embodiments of the disclosed embodiments can be designed based on what is described and / or shown in this patent document.

[0094] Cross - reference to related applications

[0095] This patent document claims the priority and benefits of Korean Patent Application No. 10 - 2021 - 0091753 filed on July 13, 2021 and Korean Patent Application No. 10 - 2021 - 0108948 filed on August 18, 2021. The entire content of each application is incorporated herein by reference in its entirety as part of the disclosure of this patent document.

Claims

1. An image sensing device, the image sensing device comprises: a pixel array, the pixel array including a plurality of image sensing pixels and phase detection pixel pairs disposed between the image sensing pixels, the plurality of image sensing pixels detecting incident light to generate a first electrical signal carrying an image in the incident light, the phase detection pixel pairs including phase detection pixels that generate a second electrical signal for calculating a phase difference between the images, wherein, the pixel array includes: a plurality of photoelectric conversion regions formed in a substrate corresponding to the image sensing pixels and the phase detection pixels; a plurality of device isolation structures disposed in the substrate to isolate the photoelectric conversion regions from each other; a plurality of color filters disposed above the substrate corresponding to the image sensing pixels and the phase detection pixel pairs; a first grid structure disposed between a color filter of a first image sensing pixel among the plurality of image sensing pixels and a color filter of a first phase detection pixel pair adjacent to the first image sensing pixel among the phase detection pixel pairs, and offset by a first distance from a first device isolation structure among the plurality of device isolation structures, the first device isolation structure being disposed between a photoelectric conversion region of the first image sensing pixel and a photoelectric conversion region of the first phase detection pixel pair; and a second grid structure disposed in the color filter of the first phase detection pixel pair and offset by a second distance different from the first distance from a second device isolation structure among the plurality of device isolation structures, the second device isolation structure being disposed between the photoelectric conversion regions of the first phase detection pixel pair.

2. The image sensing device according to claim 1, wherein, the first grid structure includes a capping layer covering a stacked structure of a first material layer and a second material layer; and the second grid structure includes the capping layer covering a single-layer structure formed of the first material layer without the second material layer.

3. The image sensing device according to claim 2, wherein, the first material layer is formed to include at least one of titanium Ti or titanium nitride TiN.

4. The image sensing device according to claim 3, wherein, the second material layer is formed to include at least one of a metal material, air, or an insulating material.

5. The image sensing device according to claim 1, wherein, each of the phase detection pixel pairs includes: two phase detection pixels adjacent to each other; or four phase detection pixels adjacent to each other.

6. The image sensing device according to claim 1, wherein, based on the position of the first phase detection pixel pair within the pixel array, the second grid structure has different second distances.

7. The image sensing device according to claim 6, wherein, the pixel array is divided into a plurality of sub-pixel regions, each of the plurality of sub-pixel regions including a predetermined number of phase detection pixel pairs; and The second distance of the second grid structure in one sub-pixel region is different from the second distance of the second grid structure in another sub-pixel region.

8. The image sensing device according to claim 7, wherein, All the second grid structures arranged in the same sub-pixel region are offset by the same distance.

9. An image sensing device, the image sensing device comprises: A pixel array, the pixel array includes a plurality of image sensing pixels and phase detection pixel pairs arranged between the image sensing pixels, the plurality of image sensing pixels detect incident light to generate a first electrical signal carrying an image in the incident light, and the phase detection pixel pairs include a plurality of phase detection pixels that generate a second electrical signal for determining a phase difference between the images, wherein, the pixel array includes: A plurality of first grid structures, the plurality of first grid structures are arranged between the image sensing pixels and between the image sensing pixels and the phase detection pixel pairs; and A plurality of second grid structures, the plurality of second grid structures are arranged between the plurality of phase detection pixels, wherein, the second grid structure has a different width from the first grid structure.

10. The image sensing device according to claim 9, wherein, The first grid structure includes a capping layer covering a stacked structure of a first material layer and a second material layer; and The second grid structure includes the capping layer covering a single-layer structure formed by the first material layer without the second material layer.

11. The image sensing device according to claim 10, wherein, The first material layer is formed to include at least one of titanium Ti or titanium nitride TiN.

12. The image sensing device according to claim 11, wherein, The second material layer is formed to include at least one of a metal material, air, or an insulating material.

13. The image sensing device according to claim 9, wherein, Each of the phase detection pixel pairs includes two adjacent phase detection pixels; or four adjacent phase detection pixels.

14. The image sensing device according to claim 9, wherein, Based on the positions of the corresponding phase detection pixel pairs, the second grid structures have different widths from each other.

15. The image sensing device according to claim 14, wherein, The pixel array is divided into a plurality of sub-pixel regions, each of the plurality of sub-pixel regions includes a predetermined number of phase detection pixel pairs; and The different second grid structures corresponding to different phase detection pixel pairs in different sub-pixel regions have different widths from each other.

16. The image sensing device according to claim 15, wherein, All the second grid structures arranged in the same sub-pixel region have the same width.

17. The image sensing device according to claim 9, wherein, The width of the second grid structure is equal to or less than the width of the device isolation structure arranged between the photoelectric conversion regions of the phase detection pixels.

18. The image sensing device according to claim 9, wherein the image sensing device further comprises a plurality of color filters disposed above the image sensing pixels and the phase detection pixel pairs.

19. The image sensing device according to claim 18, wherein, the color filters for the phase detection pixels within one phase detection pixel pair have a common color.

20. The image sensing device according to claim 18, wherein, the color filters for the phase detection pixel pairs have a common color.

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