Image sensing device

Abstract

An image sensing device includes a pixel array configured to include a plurality of pixel groups arranged in a matrix structure. Each pixel group includes: a filter configured to selectively transmit incident light; a plurality of photoelectric conversion regions arranged below the filter and arranged in a matrix structure; a first isolation structure arranged between the photoelectric conversion region and other pixel groups; a plurality of second isolation structures arranged between two adjacent photoelectric conversion regions among the plurality of photoelectric conversion regions; and a third isolation structure arranged between the plurality of second isolation structures and configured to interconnect the plurality of second isolation structures. The third isolation structure includes a cavity region formed adjacent to contact any one of the photoelectric conversion regions.

Description

Technical Field

[0001] The techniques and implementations disclosed in this patent document generally relate to an image sensing device. Background Art

[0002] Image sensing devices are devices that capture optical images by converting light into electrical signals using photosensitive semiconductor materials that react to light. With the development of the automotive, medical, computer, and communication industries, the demand for high-performance image sensing devices is increasing in various fields such as smartphones, digital cameras, game consoles, IoT (Internet of Things), robots, security cameras, and medical micro cameras.

[0003] Image sensing devices can be roughly divided into CCD (charge coupled device) image sensing devices and CMOS (complementary metal oxide semiconductor) image sensing devices. Compared with CMOS image sensing devices, CCD image sensing devices provide better image quality, but they tend to consume more power and are larger. Compared with CCD image sensing devices, CMOS image sensing devices are smaller in size and consume less power. In addition, CMOS sensors are manufactured using CMOS manufacturing technology, so the photosensitive element and other signal processing circuits can be integrated into a single chip, allowing miniaturized image sensing devices to be produced at a lower cost. For these reasons, CMOS image sensing devices are being developed for many applications including mobile devices. Summary of the invention

[0004] Various embodiments of the disclosed technology relate to an image sensing device capable of improving an imbalance between pixel signals.

[0005] According to an embodiment of the disclosed technology, an image sensing device may include a pixel array configured to include a plurality of pixel groups arranged in rows and columns and detect incident light, wherein each pixel group includes: a filter configured to selectively transmit incident light; a plurality of photoelectric conversion regions respectively disposed under the filter to convert the incident light into electrical signals; a first isolation structure disposed along an edge of each corresponding pixel group; a plurality of second isolation structures disposed between two adjacent photoelectric conversion regions of each corresponding pixel group; and a third isolation structure disposed between the plurality of second isolation structures and configured to interconnect the plurality of second isolation structures, wherein the third isolation structure includes a cavity region formed adjacent to one of the photoelectric conversion regions of each corresponding pixel group.

[0006] In some implementations, each pixel group further includes a microlens that converges incident light, and the cavity region is disposed adjacent to the photoelectric conversion region located in a direction in which the incident light is incident on the microlens.

[0007] In some implementations, each pixel group further includes a microlens that converges incident light, and the cavity region is disposed adjacent to the photoelectric conversion region located in a direction in which the incident light is emitted from the microlens.

[0008] In some implementations, the filters of the first pixel group include at least one of: a first filter configured to pass red light; a second filter configured to pass green light; and a third filter configured to pass blue light.

[0009] In some implementations, the size of the cavity region is determined based on the wavelength of light passing through the filter.

[0010] In some implementations, a cavity region disposed under the first optical filter has a size that is larger than a size of another cavity region disposed under the third optical filter.

[0011] In some implementations, the cavity region has a size according to the location of a pixel group disposed above the pixel array.

[0012] In some implementations, the size of the cavity region decreases as the corresponding pixel group is positioned closer to a center point of the pixel array.

[0013] In some implementations, each second isolation structure is disposed at the center of two adjacent photoelectric conversion regions of a corresponding pixel group.

[0014] In some implementations, the third isolation structure is disposed at the center of the pixel group.

[0015] In some implementations, a first length corresponding to a length of a third isolation structure that overlaps a first diagonal line passing through a center of a pixel group and one vertex of the pixel group is different from a second length corresponding to a length of the third isolation structure that overlaps a second diagonal line passing through a center of the pixel group and another vertex of the pixel group.

[0016] In some implementations, the photoelectric conversion regions included in each pixel group are arranged in a (2×2) matrix structure having two rows and two columns.

[0017] In some implementations, the photoelectric conversion regions included in each pixel group are arranged in a (3×3) matrix structure having three rows and three columns.

[0018] According to another embodiment of the disclosed technology, an image sensing device may include a pixel array configured to include a plurality of pixel groups, wherein the pixel groups include a first pixel group including: an optical filter configured to selectively allow incident light having a predetermined wavelength band to pass through; a plurality of photoelectric conversion regions disposed below the optical filter and arranged in rows and columns; a first isolation structure configured to isolate the plurality of photoelectric conversion regions from other pixel groups; a plurality of second isolation structures disposed between two of the plurality of photoelectric conversion regions; and a third isolation structure interconnecting the plurality of second isolation structures, wherein any one of the plurality of photoelectric conversion regions is adjacent to a cavity region extending from a center of the third isolation structure in a diagonal direction of the pixel array.

[0019] In some implementations, the first pixel group further includes a microlens, and wherein the cavity region extends parallel to a traveling direction of the incident light.

[0020] In some implementations, each of the plurality of photoelectric conversion regions has the same size.

[0021] In some implementations, the cavity region has a size that depends on the position of the first pixel group, such that the size becomes larger as the first pixel group is positioned farther from the center of the pixel array.

[0022] In some implementations, the plurality of photoelectric conversion regions are arranged in a (2×2) matrix structure having two rows and two columns.

[0023] In some implementations, the plurality of photoelectric conversion regions are arranged in a (3×3) matrix structure having three rows and three columns.

[0024] It is to be understood that both the foregoing general description and the following detailed description of the disclosed technology are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other features and advantageous aspects of the disclosed technology will become readily apparent with reference to the following detailed description when considered in conjunction with the accompanying drawings.

[0026] Figure 1 is a block diagram illustrating an example of an image sensing device based on some implementations of the disclosed technology.

[0027] Figure 2 Some implementations based on the disclosed technology are shown in Figure 1 Schematic diagram of examples of some portions of a pixel array are shown.

[0028] Figure 3is a schematic diagram showing a pixel group array and an isolation structure array included in the pixel group array according to some implementations of the disclosed technology.

[0029] Figure 4 is a diagram showing some implementations based on the disclosed technology. Figure 3 A cross-sectional view of an example of a pixel group array taken along a first cutting line is shown.

[0030] Figure 5 is a schematic diagram showing a pixel group array and an isolation structure array included in the pixel group array according to some implementations of the disclosed technology.

[0031] Figure 6 is a diagram showing some implementations based on the disclosed technology. Figure 5 A cross-sectional view of an example of a pixel group array taken along a second cutting line is shown. DETAILED DESCRIPTION

[0032] This patent document provides implementations and examples of an image sensing device capable of improving an imbalance between pixel signals. Some implementations of the disclosed technology relate to an image sensing device that can improve an imbalance between pixel signals output from individual unit pixels included in a pixel group by adjusting the shape of an isolation region included in the pixel group. The disclosed technology provides an image sensing device that can adjust the shape of an isolation region included in a pixel group according to the type of filter included in the pixel group.

[0033] Hereinafter, various embodiments will be described with reference to the accompanying drawings. However, it should be understood that the disclosed technology is not limited to a specific embodiment, but includes various modifications, equivalents and / or substitutions of the embodiments. The embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized by the disclosed technology.

[0034] Figure 1 is a block diagram illustrating an image sensing device 100 based on some implementations of the disclosed technology.

[0035] Reference Figure 1 , the image sensing device 100 may include a pixel array 110, a row driver 120, a correlated double sampler (CDS) 130, an analog-to-digital converter (ADC) 140, an output buffer 150, a column driver 160, and a timing controller 170. This discussion is by way of example only. Figure 1 Although the components of image sensing device 100 are shown, this patent document encompasses numerous other alterations, substitutions, variations, modifications, and modifications.

[0036] The pixel array 110 may include a plurality of unit imaging pixels arranged in rows and columns. In one example, the plurality of unit imaging pixels may be arranged in a two-dimensional pixel array including rows and columns. In another example, the plurality of unit imaging pixels may be arranged in a three-dimensional pixel array. The plurality of unit pixels may convert optical signals into electrical signals based on unit pixels or pixel groups, wherein the unit pixels in the pixel group share at least certain internal circuits.

[0037] The pixel group may include any number of unit pixels. For example, the unit pixels included in the pixel group may be arranged in a matrix array. The pixel array 110 may receive a drive signal including a row selection signal, a pixel reset signal, and a transfer signal from the row driver 120. Upon receiving the drive signal, the corresponding imaging pixel in the pixel array 110 may be enabled to perform operations corresponding to the row selection signal, the pixel reset signal, and the transfer signal.

[0038] The row driver 120 may enable the pixel array 110 to perform a specific operation on the imaging pixels in the corresponding row based on the command and control signals provided by the controller circuit such as the timing controller 170. In some implementations, the row driver 120 may select one or more imaging pixels arranged in one or more rows of the pixel array 110. The row driver 120 may generate a row selection signal to select one or more rows among the plurality of rows. The row driver 120 may sequentially enable a pixel reset signal for resetting the imaging pixels corresponding to at least one selected row and a transfer signal for the pixels corresponding to the at least one selected row. Therefore, as analog signals generated by the respective imaging pixels of the selected row, the reference signal and the image signal may be sequentially transferred to the CDS 130. The reference signal may be an electrical signal provided to the CDS 130 when a sensing node (e.g., a floating diffusion region node) of the imaging pixel is reset, and the image signal may be an electrical signal provided to the CDS 130 when the photocharge generated by the imaging pixel is accumulated in the sensing node.

[0039] CMOS image sensors may use correlated double sampling (CDS) to remove undesired offset values ​​(called fixed pattern noise) of pixels by sampling the pixel signal twice to remove the difference between the two samples. In one example, correlated double sampling (CDS) may remove undesired offset values ​​of pixels by comparing the pixel output voltages obtained before and after the photocharges generated by incident light are accumulated in the sensing node so that only the pixel output voltage based on the incident light may be measured. In some embodiments of the disclosed technology, CDS 130 may sequentially sample and hold the voltage levels of the reference signal and the image signal provided to each of the plurality of column lines from the pixel array 110. That is, CDS 130 may sample and hold the voltage levels of the reference signal and the image signal corresponding to each column of the pixel array 110.

[0040] In some implementations, the CDS 130 may transmit the reference signal and the image signal of each column as a correlated double sampling signal to the ADC 140 based on a control signal from the timing controller 170 .

[0041] ADC 140 is used to convert the analog CDS signal into a digital signal. In some implementations, ADC 140 may be implemented as a ramp comparison ADC. The ramp comparison ADC may include a comparator circuit for comparing an analog pixel signal with a reference signal (e.g., a ramp signal that ramps up or down) and a timer that counts until the voltage of the ramp signal matches the analog pixel signal. In some embodiments of the disclosed technology, ADC 140 may convert the correlated double sampling signal generated by CDS 130 for each column into a digital signal and output the digital signal. ADC 140 may perform counting operations and comparison operations based on the correlated double sampling signal of each column and the ramp signal provided from the timing controller 170. In this way, ADC 140 may eliminate or reduce noise, such as reset noise generated by imaging pixels, when generating digital image data.

[0042] The ADC 140 may include a plurality of column counters. Each column of the pixel array 110 is connected to the column counter, and image data may be generated by converting a correlated double sampling signal received from each column into a digital signal using the column counter. In another embodiment of the disclosed technology, the ADC 140 may include a global counter to convert a correlated double sampling signal corresponding to a column into a digital signal using a global code provided from the global counter.

[0043] The output buffer 150 may temporarily hold the column-based image data provided from the ADC 140 to output the image data. In one example, the image data provided from the ADC 140 to the output buffer 150 may be temporarily stored in the output buffer 150 based on a control signal of the timing controller 170. The output buffer 150 may provide an interface to compensate for a data rate difference or a transfer rate difference between the image sensing device 100 and other devices.

[0044] The column driver 160 may select a column of the output buffer upon receiving a control signal from the timing controller 170, and sequentially output the image data temporarily stored in the selected column of the output buffer 150. In some implementations, upon receiving an address signal from the timing controller 170, the column driver 160 may generate a column selection signal based on the address signal and select a column of the output buffer 150, thereby outputting the image data from the selected column of the output buffer 150 as an output signal.

[0045] The timing controller 170 may control operations of the row driver 120 , the ADC 140 , the output buffer 150 , and the column driver 160 .

[0046] The timing controller 170 may provide clock signals required for the operation of the various components of the image sensing device 100, control signals for timing control, and address signals for selecting rows or columns to the row driver 120, the column driver 160, and the output buffer 150. In an embodiment of the disclosed technology, the timing controller 170 may include a logic control circuit, a phase-locked loop (PLL) circuit, a timing control circuit, a communication interface circuit, and the like.

[0047] Figure 2 Some implementations based on the disclosed technology are shown in Figure 1 Schematic diagram of examples of some portions of pixel array 200 is shown.

[0048] Reference Figure 2 , the pixel array 200 may be an area for receiving incident light, and the incident light may be refracted by a module lens (not shown). The module lens may be disposed between the pixel array 200 and an object to be captured.

[0049] The pixel array 200 may include a plurality of pixel group arrays 210 to 290 arranged in a matrix structure, and each of the pixel group arrays 210 to 290 may include at least two pixel groups.

[0050] In some implementations, a pixel group may include different unit pixels positioned adjacent to each other, for example, four unit pixels positioned adjacent to each other. Figure 2 The illustrated pixel group array (eg, 210) may include four pixel groups arranged in, for example, a (2×2) matrix configuration.

[0051] Light beams having different chief ray angles (CRA) may be incident on the plurality of pixel group arrays 210 to 290. The chief ray angle (CRA) may refer to an angle between a chief ray passing through a center point of an aperture and a straight line connecting a center point of a lens to a center point of an aperture.

[0052] As described above, after the incident light is refracted by the module lens (not shown), the incident light may be incident on the pixel array 200 after passing through the focus of the module lens.

[0053] As the distance between the incident light and the center point of the pixel array 200 becomes longer, the incident light having passed through the focus of the module lens may be refracted at a larger angle. Therefore, one incident light incident on a pixel group array (e.g., 210) positioned near a corner or vertex of the pixel array 200 may have a larger chief ray angle (CRA) than one incident light incident on a pixel group array (e.g., 250) disposed at the center of the pixel array 200.

[0054] In some implementations, the unit pixels included in one pixel group may share one microlens and one filter. Each unit pixel may include one photoelectric conversion region corresponding to one unit pixel. Therefore, a pixel group array having four pixel groups (e.g., 210) may include four microlenses for each of the four pixel groups, with a total of 16 photoelectric conversion regions.

[0055] In some other implementations, different unit pixels that share one microlens and one filter may construct a (3×3) matrix structure or a (4×4) matrix structure, rather than being limited to a (2×2) matrix structure. In this case, one pixel group array may include four microlenses and 36 photoelectric conversion regions, or may include 64 photoelectric conversion regions.

[0056] The image sensing device 100 may form an image of a target object to be captured while receiving pixel signals from respective pixel groups included in the pixel array 200 .

[0057] Four unit pixels included in one pixel group may share only one filter. Therefore, the image sensing device 100 may create image information of a target object while receiving pixel signals from the unit pixels sharing the filter.

[0058] The image sensing device 100 may calculate four pixel signals respectively obtained from four unit pixels included in one pixel group, and thus may obtain a signal corresponding to the pixel group based on the calculated four pixel signals. For example, each pixel group may include sensing pixels having a color filter designed to capture a color image, and different sensing pixels having a color filter within the pixel group may be arranged in a desired color pattern, such as a Bayer color pattern based on red, green, and blue, where red is 25%, green is 50%, and blue is 25%, such as Figure 3 and Figure 5 as shown in the example.

[0059] When an imbalance occurs between pixel signals generated from unit pixels included in a pixel group, image information of an object may be degraded. When incident light incident on one pixel group is not evenly separated with respect to the unit pixels included in the pixel group, a difference in pixel signals may be generated according to the positions of the unit pixels. When pixel signals of unit pixels included in the same pixel group are different from each other, noise may occur in the calculation result of the pixel signal, and image information about the object may be degraded.

[0060] Specifically, for unit pixels arranged in a diagonal direction within a pixel group, the amount of incident light isolated by the isolation structure according to the chief ray angle (CRA) of the incident light may become different from each other, which causes an imbalance between pixel signals. As a result, such an imbalance between pixel signals output from pixel groups included in a pixel group array (e.g., 210) positioned away from the center of the pixel array 200 may inevitably increase. The CRA of incident light incident on a pixel group positioned away from the center of the pixel array may be greater than the CRA of incident light incident on a pixel group positioned closer to the center of the pixel array. Therefore, the isolation structure located at the center of a pixel group positioned away from the center of the pixel array separates the incident light more uniformly than the separation structure located at the center of a pixel group located near the center of the pixel array. Therefore, the shape or position of the separation structure may be adjusted to uniformly separate the incident light.

[0061] Some implementations of the disclosed technology configure the isolation structure of the image sensing device 100 to include a cavity region to reduce the imbalance between pixel signals, thereby finely adjusting the amount of received light. Using the isolation structure including the cavity region, the image sensing device 100 can adjust the amount of received light received by each photoelectric conversion region, while the photoelectric conversion regions included in the pixel group have the same size.

[0062] In addition, upon receiving pixel signals generated by unit pixels included in respective pixel groups, the image sensing device 100 may create focus information on a target object to be captured.

[0063] The image sensing device 100 may perform an autofocus operation in which signals obtained from four unit pixels included in one pixel group are compared with each other, and a phase difference between the signals is detected according to the comparison result, thereby resulting in the implementation of an autofocus function. Therefore, if the imbalance between the signals obtained from the unit pixels included in one pixel group increases, the focus detection operation may not be performed correctly. In a unit pixel located at a diagonal position relative to the center of a pixel array in the same pixel group, the imbalance of the pixel signal may be greater.

[0064] For example, the image sensing device 100 may allow incident light applied to the pixel array 200 through a module lens (not shown) to be isolated / detected for each unit pixel included in the same pixel group, and may calculate the phase of the incident light based on the pixel signal detected by each unit pixel. For example, when the sizes of the pixel signals to be compared with each other are the same, the image sensing device 100 may determine that the module lens (not shown) is in the focus position.

[0065] When pixel signals to be compared with each other have different values, the image sensing device 100 may move a module lens (not shown) so that the pixel signal values ​​become identical to each other, thereby adjusting the focus.

[0066] Figure 3 is a schematic diagram showing a pixel group array 300 and isolation structures in an example of an isolation structure array included in the pixel group array 300 based on some implementations of the disclosed technology.

[0067] Reference Figure 3 , the pixel group array 300 may correspond to Figure 2 Pixel group array 210 is shown.

[0068] The pixel group array 300 may include, for example, four pixel groups PG1 to PG4 including a first pixel group PG1 , a second pixel group PG2 , a third pixel group PG3 , and a fourth pixel group PG4 .

[0069] Each of the pixel groups PG1 to PG4 may include a plurality of photoelectric conversion regions for converting incident light into photocharges, a microlens for guiding the incident light to the photoelectric conversion region, and a filter for selectively passing light that has passed through the microlens according to the wavelength of the light. For the sake of convenience of description, a detailed description thereof will be omitted herein.

[0070] Figure 3 The isolation structure or isolation structure array in the example may include a plurality of first isolation structures 341a, 341b, 341c and 341c, a plurality of second isolation structures 342a, 342b, 342c and 342d, and a plurality of third isolation structures 343a, 343b, 343c and 343d.

[0071] The first to third isolation structures 341a to 341d, 342a to 342d, and 343a to 343d may isolate adjacent photoelectric conversion regions from each other. In addition, the first to third isolation structures 341a to 341d, 342a to 342d, and 343a to 343d may have a different refractive index from the substrate layer on which the isolation structures are formed, and may isolate light incident on the pixel array 200 for each photoelectric conversion region.

[0072] For the convenience of description, the same description of the pixel groups PG1 to PG4 will be omitted herein, and for the sake of brevity, the following description will focus on the first pixel group PG1 .

[0073] The first pixel group PG1 may include a single first isolation structure 341 a , four second isolation structures 342 a , and a single third isolation structure 343 a .

[0074] The first isolation structure 341a may be disposed along the outer edge of the first pixel group PG1 to separate and isolate the unit pixel in the first pixel group PG1 from surrounding and adjacent pixel groups (e.g., adjacent pixel groups PG2 and PG3 and diagonally displaced pixel group PG4). The first isolation structure 341a is disposed between the first pixel group PG1 and other pixel groups PG2 and PG3 that are in contact with the first pixel group PG1.

[0075] In some implementations, the first isolation structure 341 a may electrically and physically isolate the photoelectric conversion region included in the first pixel group PG1 from other photoelectric conversion regions included in other pixel groups PG2 and PG3 adjacent to each other.

[0076] The second isolation structure 342a may be disposed between two adjacent photoelectric conversion regions included in the first pixel group PG1. The second isolation structure 342a may electrically and physically isolate the photoelectric conversion regions included in the first pixel group PG1 from each other. For example, the second isolation structure 342a may be located between two adjacent photoelectric conversion regions.

[0077] In some implementations, each of the second isolation structures 342 a may be formed to extend from the center of the first pixel group PG1 toward the first isolation structure 341 a .

[0078] The third isolation structure 343a may be located at the center of the first pixel group PG1. The center of the first pixel group PG1 may refer to a region spaced apart from each photoelectric conversion region included in the pixel group PG1 by the same distance. In addition, the third isolation structure 343a may be disposed between the second isolation structures 342a.

[0079] The third isolation structure 343a may include a cavity region (ca). The cavity region (ca) may be included in the third isolation structure 343a and may be adjacent to at least one of the four photoelectric conversion regions adjacent to the third isolation structure 343a. In some implementations, when the incident light travels in a direction parallel to Figure 3 In the diagonal direction of the third isolation structure 343a, when there are two photoelectric conversion regions located in the pixel array group to be parallel to the advancing direction of the incident light, the cavity region (ca) may be adjacent to any one of the two photoelectric conversion regions located parallel to the advancing direction of the incident light. The cavity region (ca) may be formed to extend from the photoelectric conversion region located adjacent to the cavity region (ca) toward the center point of the third isolation structure 343a.

[0080] Here, the first width may refer to a length of the third isolation structure 343a overlapping with a first diagonal line passing through the center of the pixel group PG1 and one vertex of the pixel group PG1. The second width may refer to a length of the third isolation structure 343a overlapping with a second diagonal line passing through the center of the pixel group PG1 and another vertex of the pixel group PG1. The cavity area (ca) may be formed so that the first width and the second width are different from each other. The cavity area (ca) may be formed so that the first width and the second width are different from each other, thereby adjusting the amount of light beams incident on unit pixels arranged in a diagonal direction.

[0081] By forming the cavity region (ca), the photoelectric conversion region positioned adjacent to the cavity region (ca) can obtain an additional amount of received light compared to when the cavity region (ca) is not formed. In addition, as the cavity region (ca) is formed, among the unit pixels included in the first pixel group PG1, the pixel signals of some unit pixels including the photoelectric conversion region positioned adjacent to the cavity region (ca) and the pixel signals of other pixels located in the diagonal direction of the unit pixel including the cavity region (ca) can be adjusted by controlling the amount of incident light separated by the third isolation structure (343a). More specifically, as the cavity region (ca) is formed, the position of the center of the third isolation structure (343a) that separates the incident light is adjusted.

[0082] In some implementations, shapes of the cavity regions (eg, ca, cb, cc, and cd) may vary according to locations of pixel groups (eg, PG1 to PG4 ) included in the pixel array 200 .

[0083] For example, in a cavity region included in a pixel group far from the center point of the pixel array 200 , a length extending from the photoelectric conversion region toward the center point of each of the third isolation structures 343 a to 343 d may become long.

[0084] For example, each of the first to third isolation structures 341a to 343a may include silicon oxide. In some other implementations, each of the first to third isolation structures 341a to 343a may include a metal, such as tungsten (W).

[0085] The above description may be equally applied to the isolation structures 341 b ˜ 343 b , 341 c ˜ 343 c , and 341 d ˜ 343 d respectively included in the second pixel group PG2 , the third pixel group PG3 , and the fourth pixel group PG4 .

[0086] Each of the pixel groups PG1, PG2, PG3, and PG4 may include filters R, G, and B for selectively passing incident light according to wavelength. For example, each of the pixel groups PG1, PG2, PG3, and PG4 may include at least one of a first filter (R) for passing only red light, a second filter (G) for passing only green light, and a third filter (B) for passing only blue light.

[0087] The wavelength of red light can be set to 620nm to 750nm, the wavelength of green light can be set to 495nm to 570nm, and the wavelength of blue light can be set to 450nm to 495nm.

[0088] In some implementations, the first to third filters R, G, and B may be arranged in a Bayer pattern over the pixel array 200. The Bayer pattern may refer to a pattern in which one first filter (R), two second filters (G), and one third filter (B) are arranged in a (2×2) matrix and the two second filters (G) are arranged in a diagonal direction.

[0089] For example, the first pixel group PG1 may include a first filter (R), and each of the second and third pixel groups PG2 and PG3 may include a second filter (G). In addition, the fourth pixel group PG4 may include a third filter (B).

[0090] As the advancing path of the incident light changes according to the refractive index of the light that has selectively passed through the filter, the shapes of the cavity regions (ca, cb, cc and cd) respectively included in the third isolation structures 343a, 343b, 343c and 343d may change according to the types of filters respectively included in the pixel groups PG1, PG2, PG3 and PG4.

[0091] For example, as the wavelength of light becomes longer, the refractive index becomes smaller. The size of the cavity area (ca) included in the first pixel group PG1 provided with the first filter (R) may be larger than the size of the cavity area (cd) included in the fourth pixel group PG4 provided with the third filter (B).

[0092] The size of each cavity region (ca, cb, cc, cd) may vary according to the wavelength of incident light having passed through the filter. The size of the cavity region (ca) located under the first filter (R) may be larger than the size of another cavity region (cd) located under the third filter (B).

[0093] By the cavity regions (ca, cb, cc, cd) respectively included in the third isolation structures 343a, 343b, 343c, and 343d, signal imbalance between unit pixels diagonally adjacent to each other may be easily removed.

[0094] In some other implementations, the size of the cavity regions (ca, cb, cc, cd) may vary depending on the location of the pixel group array 300 above the pixel array 200 .

[0095] As the incident light becomes closer to the center of the pixel array 200, the chief ray angle (CRA) of the incident light becomes smaller. Therefore, a difference in pixel signals between unit pixels included in a pixel group positioned adjacent to the center of the pixel array 200 may be smaller than a signal difference between unit pixels included in another pixel group positioned away from the center of the pixel array 200.

[0096] Therefore, as the pixel group is located closer to the center of the pixel array 200, the size of the cavity region included in each third isolation structure becomes smaller.

[0097] In some implementations, pixel groups (eg, PG1, PG2, PG3, and PG4), each including a photoelectric conversion region arranged in a (2×2) matrix structure, may include a single first isolation structure, four second isolation structures, and a single third isolation structure.

[0098] In some other implementations, a pixel group may include a plurality of photoelectric conversion regions arranged in an (n×n) matrix structure (where “n” is an integer of 3 or greater). The photoelectric conversion regions included in each pixel group may be arranged to share filters and microlenses, and may be arranged in, for example, a nona (3×3) structure or a hexa (6×6) structure.

[0099] When the pixel group includes a plurality of photoelectric conversion regions arranged in a nona (3×3) structure, the first isolation structure may be disposed between different pixel groups positioned adjacent to each other. In addition, the second isolation structure may be disposed between two adjacent photoelectric conversion regions included in one pixel group. The third isolation structure may be disposed between the plurality of second isolation structures, and the plurality of second isolation structures may be interconnected.

[0100] The photoelectric conversion regions included in the pixel groups are arranged in a nona (3×3) structure, and each pixel group may include a single first isolation structure, 12 second isolation structures, and four third isolation structures.

[0101] Figure 4 is a diagram showing some implementations based on the disclosed technology. Figure 3 The cross-sectional view 400 of an example of the pixel group array 400 is taken along the first cutting line AA′. Figure 4 The paths of incident light are shown, each with an exemplary CRA. Figure 4 The cross-sectional view 400 shown may be Figure 3 The cross-sectional views corresponding to the first pixel group PG1 and the fourth pixel group PG4 are shown.

[0102] As the incident light moves closer to the center of the pixel array 200, the CRA of the incident light becomes smaller. On the other hand, as the incident light moves closer to the edge or vertex of the pixel array 200, the CRA of the incident light becomes larger.

[0103] Incident light may be guided to the photoelectric conversion regions 451a, 454a, 451d, and 454d through the microlenses 411 and 414. The microlenses 411 and 414 may be shifted toward the center of the pixel array 200 in response to the CRA of the incident light.

[0104] Each of the filters 421 and 424 can selectively pass or transmit incident light according to wavelength. In some implementations, the filter 421 can refer to a first filter (R) for passing or transmitting red light, and the filter 424 can refer to a third filter (B) for passing or transmitting blue light.

[0105] The filter 421 may be formed to overlap with the grid structure 431, and the filter 424 may be formed to overlap with the grid structure 434. Each of the grid structures 431 and 434 may isolate incident light of each pixel group (e.g., PG1 or PG4). In some implementations, each of the grid structures 431 and 434 may include a metal such as tungsten (W), or may include an air layer.

[0106] The filters 421 and 424 may be shifted toward the center of the pixel array 200 in response to the shift degree of the micro lenses 411 and 414 .

[0107] The planarization layer 460 may be formed under the filters 421 and 424. As the planarization layer 460 is formed, physical stability of the pixel array 200 may be increased.

[0108] A substrate layer 470 formed to include isolation structures 441a, 443a, 441d, and 443d and photoelectric conversion regions 451a, 454a, 451d, and 454d may be disposed under the planarization layer 460. The substrate layer 470 may include a semiconductor substrate layer or an epitaxial layer.

[0109] In addition, the third isolation structure 443a may include a cavity region (ca), and the third isolation structure 443d may include a cavity region (cd). By adjusting the width of each cavity region (ca, cd), the isolation ratio of the incident light respectively incident on two adjacent photoelectric conversion regions (e.g., 451a and 454a or 451d and 454d) arranged to face each other based on the third isolation structure 443a or 443d can be adjusted. By adjusting the width of each cavity region (ca, cd), the center of the third isolation structure (443a, 443d) where the incident light converges can be adjusted.

[0110] In some implementations, when a cavity region (ca) is formed, the amount of incident light on a photoelectric conversion region (e.g., 454a) positioned adjacent to the formed cavity region (ca) may be greater than the amount of incident light generated when the cavity region (ca) is not formed.

[0111] In a case where the amount of light incident on a pixel group is constant regardless of whether a cavity region (ca) exists, if a cavity region (ca) is formed, the amount of light incident on a photoelectric conversion region 451a arranged to face a photoelectric conversion region 454a positioned adjacent to the cavity region (ca) may be smaller than when the cavity region (ca) is not formed.

[0112] In addition, the direction in which each cavity region (ca, cd) is formed may be determined according to the CRA of the incident light. For example, each cavity region (ca, cd) may be located in the direction along which the incident light is incident. For example, since the CRA of the incident light is along the diagonal direction, the cavity regions (ca, cd) are formed along the diagonal direction, such as Figure 3 shown.

[0113] When the center point of the third isolation structure 443a is the same as the center point PGC1 of the pixel group and does not include the cavity area (ca), and the center point of the third isolation structure 443d is the same as the center point PGC4 of the pixel group and does not include the cavity area (cd), the amount of light received by the photoelectric conversion region 451a or 451d adjacent to a specific point where the incident light converges may be greater than the amount of light received by the other photoelectric conversion region 454a or 454d.

[0114] In the case where the third isolation structure (eg, 443a) includes a cavity region (ca), the center of the third isolation structure 443a is spaced apart from the center of the pixel group PGC1. In this case, that is, in the case where the third isolation structure includes a cavity region, Figure 4 As shown, the center of the third isolation structure 443a is located at the position where the incident light converges in the first pixel group PG1. Similarly, in the case where the third isolation structure (e.g., 443d) includes a cavity region (cd), the center of the third isolation structure 443d is not located at the center of the pixel group PGC4, but is located at the position where the incident light converges in the fourth pixel group PG4. In the case where the incident light converges at the same center as the third isolation structure 443a, the incident light can be uniformly isolated and applied to the photoelectric conversion regions (e.g., 451a and 454a) adjacent to each other. By forming the cavity region (ca or cd), the amount of light received by each of the photoelectric conversion regions 451a and 454a arranged in the diagonal direction based on the third isolation structure 443a interposed therebetween can be finely adjusted.

[0115] In some implementations, the width of each cavity region (ca, cd) may be determined according to the path of the incident light. For example, the path of the incident light passing through both the microlens 411 and the filter 421 and the path of the incident light passing through both the microlens 414 and the filter 424 may be changed according to the difference between the refractive indices of the light wavelengths.

[0116] Incident light having passed through the first optical filter 421 configured to pass red light may be less refracted than other incident light having passed through the third optical filter 424 configured to pass blue light.

[0117] Therefore, a distance between a point where incident light having passed through the first filter 421 converges and a center point PGC1 of the first pixel group may be longer than a distance between a point where incident light having passed through the third filter 424 converges and a center point PGC4 of the fourth pixel group.

[0118] The width of the cavity region (ca) included in the third isolation structure 443a located below the first optical filter 421 may be formed to be larger than the width of the cavity region (cd) included in the third isolation structure 443d located below the third optical filter 424 so that the difference between the refractive indices of the light wavelengths may be corrected.

[0119] As described above, the width of the cavity region (ca, cd) is adjusted so that the amount of light incident on the photoelectric conversion regions 451a, 454a, 451d and 454d can be adjusted, and the imbalance between pixel signals output from two unit pixels diagonally adjacent to each other based on the third isolation structure 443a or 443d inserted therebetween can be eliminated.

[0120] Figure 5 is a schematic diagram showing a pixel group array 500 and an isolation structure array included in the pixel group array according to other implementations of the disclosed technology.

[0121] Reference Figure 5 , the pixel group array 500 may include, for example, four pixel groups PG1', PG2', PG3', and PG4'. For ease of description, the four pixel groups may include a first pixel group PG1', a second pixel group PG2', a third pixel group PG3', and a fourth pixel group PG4'.

[0122] Included in Figure 5 The remaining portions of the isolation structure array in the pixel group array 500 except the third isolation structures 543a, 543b, 543c and 543d may have the same structure as that included in the Figure 3The isolation structure arrays in the pixel group array 300 shown are substantially of the same shape, so for the sake of brevity, redundant descriptions thereof will be omitted herein, and the following description will focus on the third isolation structures 543a, 543b, 543c, and 543d.

[0123] In some other implementations, the third isolation structure 543a may include a cavity region (ca'), the second isolation structure 543b may include a cavity region (cb'), the third isolation structure 543c may include a cavity region (cc'), and the fourth isolation structure 543d may include a cavity region (cd').

[0124] In some implementations, each cavity region (ca', cb', cc', cd') may be disposed to be positioned adjacent to at least one of two diagonally arranged photoelectric conversion regions among a plurality of unit pixels included in each of the pixel groups PG1' to PG4'. The diagonal direction in which the two unit pixels are arranged may be parallel to the advancing direction of the incident light.

[0125] For example, the third isolation structure 543a included in the first unit pixel PG1' may include a cavity region (ca'). The cavity region (ca') may be formed to be located adjacent to an upper left photoelectric conversion region among the photoelectric conversion regions arranged in a diagonal direction.

[0126] In addition, the third isolation structure 543d included in the fourth unit pixel PG4' may include a cavity region (cd'). The cavity region (cd') may be formed to be located adjacent to a lower right photoelectric conversion region among the photoelectric conversion regions arranged in a diagonal direction.

[0127] Each photoelectric conversion region positioned adjacent to the cavity region (ca', cb', cc', cd') can obtain an additional amount of received light. As a result, the amount of light received by the adjacent photoelectric conversion region can be adjusted according to the position of the cavity region (ca', cb', cc', cd') and the shape of the cavity region (ca', cb', cc', cd').

[0128] In some implementations, the position of the cavity region (eg, ca′) formed in the pixel group (eg, PG1′) may be determined based on a pixel signal output from a unit pixel included in the pixel group PG1′.

[0129] Among the unit pixels included in the pixel group PG1', the largest difference occurs between pixel signals output from the unit pixels positioned parallel to the advancing direction of the incident light. Therefore, the cavity area (ca') may be formed to be positioned adjacent to any one of the unit pixels positioned parallel to the advancing direction of the incident light within the pixel group PG1'.

[0130] In some other implementations, a pixel signal output from a unit pixel may be affected by another unit pixel adjacent to the unit pixel.

[0131] For example, a unit pixel including a first filter configured to pass or transmit red light (e.g., a unit pixel included in pixel group PG1') may receive incident light from a unit pixel (e.g., a unit pixel included in pixel group PG2' or PG3'). This is due to the difference in refractive index between the first filter and the second filter. As a result, an imbalance between pixel signals may occur in response to the arrangement shape of the first filter and the second filter disposed above pixel array 200.

[0132] In some implementations, as the cavity area (ca′) formed in the third isolation structure 543 a is adjusted, the imbalance between pixel signals affected by the arrangement of the optical filter can be eliminated.

[0133] Figure 6 is a diagram showing some implementations based on the disclosed technology. Figure 5 An example cross-sectional view 600 of a pixel group array taken along a second cutting line BB′ is shown. Figure 6 The paths of incident light are shown, each with an exemplary CRA. Figure 6 The cross-sectional view 600 shown may be Figure 5 The cross-sectional views corresponding to the first pixel group PG1 ′ and the fourth pixel group PG4 ′ are shown.

[0134] Figure 6 The microlenses 611 and 614, the filters 621 and 624, the planarization layer 660, the photoelectric conversion regions 651a, 654a, 651d and 654d, and the first isolation structures 641a and 641d shown may be connected to the Figure 4 The third isolation structures 643a and 643d are substantially the same as those of the third isolation structures 643a and 643d, and thus, for the convenience of description, these redundant descriptions thereof will be omitted herein. Hereinafter, for the convenience of description, the following description will focus on the third isolation structures 643a and 643d and the cavity regions ca' and cd' respectively included in the third isolation structures 643a and 643d.

[0135] The cavity region (ca') included in the third isolation structure 643a disposed under the first optical filter 621 may be formed at a position opposite to the cavity region (cd') included in the third isolation structure 643d disposed under the third optical filter 624. For example, the cavity region (ca') of the third isolation structure 643a is positioned adjacent to the photoelectric conversion region 651a further away from the center of the pixel group array 500, and the cavity region (cd') of the third isolation structure 643d is positioned adjacent to the photoelectric conversion region 654d further away from the center of the pixel group array 500. Therefore, the cavity region (ca') of the third isolation structure 643a is positioned to face the photoelectric conversion region 651a, and the cavity region (cd') of the third isolation structure 643d is positioned to face the photoelectric conversion region 654d. The pixel group PG1 ′ including the first filter 621 may receive additional refracted incident light from a pixel group including a second filter adjacent to the first filter 621 (and a unit pixel included in the pixel group).

[0136] In some implementations, a unit pixel included in the pixel group PG1' may receive incident light from other unit pixels included in other pixel groups adjacent to the pixel group PG1'. In this case, the amount of incident light received by the unit pixel of the pixel group PG1' may change according to the position of the unit pixel. In order to correct the imbalance between pixel signals affected by the refracted incident light, the cavity area (ca') included in the third isolation structure 643a disposed under the first optical filter 621 may be arranged relative to the cavity area (cd') included in the third isolation structure 643d disposed under the third optical filter 624.

[0137] As apparent from the above description, an image sensing device based on some implementations of the disclosed technology may improve an imbalance between pixel signals output from respective unit pixels included in a pixel group by adjusting the shape of an isolation region included in the pixel group.

[0138] In addition, an image sensing device based on some implementations of the disclosed technology may adjust the shape of an isolation region included in a pixel group according to a type of filter included in the pixel group.

[0139] The embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized through the above-mentioned patent documents.

[0140] Those skilled in the art will appreciate that the disclosed technology can be implemented in a specific manner other than that described herein. In addition, claims not explicitly proposed in the appended claims may be proposed in subsequent amendments after filing an application or in a subsequent application filed later.

[0141] Although a number of exemplary embodiments have been described, it should be understood that modifications and / or enhancements to the disclosed embodiments and other embodiments are contemplated based on what is described and / or illustrated in this patent document.

[0142] CROSS-REFERENCE TO RELATED APPLICATIONS

[0143] This patent document claims priority to and the benefit of Korean Patent Application No. 10-2021-0102761, filed on August 4, 2021, the disclosure of which is incorporated by reference in its entirety as a part of the disclosure of this patent document.

Claims

1. An image sensing device, comprising: a pixel array including a plurality of pixel groups arranged in rows and columns and detecting incident light, Wherein, each of the pixel groups comprises: an optical filter that selectively transmits the incident light; a plurality of photoelectric conversion regions, the plurality of photoelectric conversion regions being respectively arranged under the optical filter to convert the incident light into an electrical signal; A first isolation structure, wherein the first isolation structure is arranged along the edge of each corresponding pixel group; a plurality of second isolation structures, wherein the plurality of second isolation structures are disposed between two adjacent photoelectric conversion regions of each corresponding pixel group; and a third isolation structure disposed between the plurality of second isolation structures and interconnecting the plurality of second isolation structures, The third isolation structure includes a cavity region formed adjacent to one of the photoelectric conversion regions of each corresponding pixel group.

2. The image sensing device according to claim 1, wherein: Each of the pixel groups further includes a microlens for converging the incident light; and The cavity region is disposed adjacent to a photoelectric conversion region located in a direction in which the incident light is incident on the microlens.

3. The image sensing device according to claim 1, wherein: Each of the pixel groups further includes a microlens for converging the incident light; and The cavity region is disposed adjacent to a photoelectric conversion region located in a direction in which the incident light is emitted from the microlens.

4. The image sensing device according to claim 1, wherein: The filter of the first pixel group includes at least one of the following: a first filter that passes red light; a second optical filter that passes green light; and A third filter passes blue light.

5. The image sensing device according to claim 4, wherein: The cavity region has a size determined based on a wavelength of light passing through the filter.

6. The image sensing device according to claim 5, wherein: The cavity region disposed under the first optical filter has a size larger than a size of another cavity region disposed under the third optical filter.

7. The image sensing device according to claim 1, wherein: The cavity region has a size according to a position of the pixel group disposed above the pixel array.

8. The image sensing device according to claim 7, wherein: As the corresponding pixel group is located closer to the center point of the pixel array, the size of the cavity area is smaller.

9. The image sensing device according to claim 1, wherein: Each of the second isolation structures is disposed at a center of the two adjacent photoelectric conversion regions of the corresponding pixel group.

10. The image sensing device according to claim 1, wherein: The third isolation structure is disposed at the center of the pixel group.

11. The image sensing device according to claim 1, wherein: A first length corresponding to the length of the third isolation structure overlapping with a first diagonal line passing through the center of the pixel group and one vertex of the pixel group is different from a second length corresponding to the length of the third isolation structure overlapping with a second diagonal line passing through the center of the pixel group and another vertex of the pixel group.

12. The image sensing device according to claim 1, wherein: The photoelectric conversion regions included in each of the pixel groups are arranged in a (2×2) matrix structure having two rows and two columns.

13. The image sensing device according to claim 1, wherein: The photoelectric conversion regions included in each of the pixel groups are arranged in a (3×3) matrix structure having three rows and three columns.

14. An image sensing device, comprising: a pixel array, the pixel array comprising a plurality of pixel groups, The pixel group includes a first pixel group, and the first pixel group includes: an optical filter that selectively passes incident light having a predetermined wavelength band; a plurality of photoelectric conversion regions disposed below the optical filter and arranged in rows and columns; a first isolation structure, wherein the first isolation structure isolates the plurality of photoelectric conversion regions from other pixel groups; a plurality of second isolation structures, the plurality of second isolation structures being disposed between two photoelectric conversion regions among the plurality of photoelectric conversion regions; and a third isolation structure interconnecting the plurality of second isolation structures, Wherein, any one of the plurality of photoelectric conversion regions is adjacent to a cavity region extending from a center of the third isolation structure in a diagonal direction of the pixel array.

15. The image sensing device according to claim 14, wherein: The first pixel group further includes a microlens, and Wherein, the cavity region extends parallel to the advancing direction of the incident light.

16. The image sensing device according to claim 14, wherein: Each of the plurality of photoelectric conversion regions has the same size.

17. The image sensing device according to claim 14, wherein: The cavity region has a size that depends on the position of the first pixel group, such that the size becomes larger as the first pixel group is located further away from the center of the pixel array.

18. The image sensing device according to claim 14, wherein: The plurality of photoelectric conversion regions are arranged in a (2×2) matrix structure having two rows and two columns.

19. The image sensing device according to claim 14, wherein: The plurality of photoelectric conversion regions are arranged in a (3×3) matrix structure having three rows and three columns.

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