Trench balancing structure pattern in red photodiode of pixel array with four-bayer color filter

Abstract

The present disclosure relates to a trench balancing structure pattern in a red photodiode of a pixel array having a four-bayer color filter. A pixel array includes 2x2 photodiode groups to generate image charges in response to incident light directed through a backside of a semiconductor layer. A four-bayer color filter is disposed on the backside of the semiconductor layer over the 2x2 photodiode groups. Each color filter in the four-bayer CFA is disposed over a respective one of a plurality of 2x2 photodiode groups. Trench balancing structures are disposed in the semiconductor layer. Each of the trench balancing structures is disposed in the semiconductor layer between one of the photodiodes and a respective one of red color filters in the four-bayer color filter. None of the trench balancing structures in the trench balancing structures is disposed between any of the photodiodes and a respective green or blue color filter in the four-bayer color filter.

Description

Technical Field

[0001] This disclosure generally relates to image sensors, and specifically, but not exclusively, to image sensors having a pixel array including a Quad Bayer color filter. Background Technology

[0002] Image sensors have become ubiquitous and are now widely used in digital cameras, cellular phones, security cameras, and medical, automotive, and other applications. As image sensors are integrated into a wider range of electronic devices, there is a desire to enhance their functionality and performance metrics in as many ways as possible (e.g., resolution, power consumption, dynamic range) through device architecture design and image acquisition processing. The technologies used to manufacture image sensors continue to advance rapidly. For example, the need for higher resolution and lower power consumption has driven further miniaturization and integration of these devices.

[0003] A typical image sensor operates in response to image light incident on it from an external scene. The image sensor comprises an array of pixels with photosensitive elements (e.g., photodiodes) that absorb a portion of the incident image light and immediately generate an image charge upon absorption. The image charge generated by the pixel light can be measured as an analog output image signal on the bit lines, which varies as a function of the incident image light. In other words, the amount of image charge generated is proportional to the intensity of the image light, and this image charge is read out as an analog image signal from the bit lines and converted into a digital value to produce a digital image (e.g., image data) representing the external scene. The analog image signal on the bit lines is coupled to a readout circuit that includes an input stage with analog-to-digital converter (ADC) circuitry to convert those analog image signals from the pixel array into digital image signals. Summary of the Invention

[0004] According to one aspect of this disclosure, a pixel array is provided. The pixel array includes: a plurality of 2×2 photodiode groups located in a semiconductor layer to generate image charge in response to incident light guided through the rear side of the semiconductor layer; a quad Bayer color filter array (CFA) disposed on the rear side of the semiconductor layer above the plurality of 2×2 photodiode groups, wherein the quad Bayer CFA includes a plurality of color filters, wherein the plurality of color filters includes a red color filter, a green color filter, and a blue color filter, wherein each color filter in the quad Bayer CFA is disposed above a corresponding one of the plurality of 2×2 photodiode groups; and a plurality of trench balancing structures disposed in the semiconductor layer, wherein each of the plurality of trench balancing structures is disposed in the semiconductor layer between one of the photodiodes and a corresponding one of the red color filters in the quad Bayer CFA, wherein none of the plurality of trench balancing structures is disposed between any of the photodiodes and a corresponding green or blue color filter in the quad Bayer CFA.

[0005] According to another aspect of this disclosure, an imaging system is provided. The imaging system includes: a pixel array comprising: a plurality of 2×2 photodiode groups located in a semiconductor layer to generate image charge in response to incident light guided through the rear side of the semiconductor layer; a four-Bayer color filter array (CFA) disposed above the plurality of 2×2 photodiode groups on the rear side of the semiconductor layer, wherein the four-Bayer CFA includes a plurality of color filters, wherein the plurality of color filters includes a red color filter, a green color filter, and a blue color filter, wherein each color filter in the four-Bayer CFA is disposed above a corresponding one of the plurality of 2×2 photodiode groups; and a plurality of trenches. A balancing structure disposed in the semiconductor layer, wherein each of the plurality of trench balancing structures is disposed in the semiconductor layer between one of the photodiodes and a corresponding one of the red color filters in the four Bayer CFAs, wherein none of the plurality of trench balancing structures is disposed between any of the photodiodes and a corresponding green or blue color filter in the four Bayer CFAs; a control circuit system coupled to the pixel array to control the operation of the pixel array; and a readout circuit system coupled to the pixel array to read out image data from the pixel array. Attached Figure Description

[0006] Non-limiting and non-exhaustive embodiments of this disclosure are described with reference to the following figures, wherein, unless otherwise specified, similar reference numerals in all views refer to similar parts.

[0007] Figure 1The illustration depicts an example of an imaging system with an exemplary pattern of a trench balancing structure according to the teachings of this disclosure, the trench balancing structure being incorporated together with a group of 2×2 photodiodes below a red filter of a four-Bayer filter above a pixel array.

[0008] Figure 2A This is a top view illustrating an example of a group of adjacent 2×2 photodiodes in a pixel array according to the teachings of this disclosure, the adjacent 2×2 photodiode groups being below the red, green and blue color filters of a four-Bayer filter.

[0009] Figure 2B It is based on the teachings of this disclosure that has the following characteristics: Figure 2A An exemplary cross-sectional view of a 2×2 photodiode group of a pixel array with an exemplary trench balance structure below the red filter of a four-Bayer filter, as illustrated in the figure.

[0010] Figure 3A This is an exemplary top view of a 2×2 photodiode group, representing an example of a trench balancing structure contained beneath a red color filter of a four-Bayer filter, according to the teachings of this disclosure.

[0011] Figure 3B This is an exemplary top view of a 2×2 photodiode group, representing another example of a trench balancing structure contained below a red color filter of a four-Bayer filter, according to the teachings of this disclosure.

[0012] Figure 4A This is an exemplary top view of a 2×2 photodiode group, representing yet another example of a trench balancing structure contained beneath a red color filter of a four-Bayer filter, according to the teachings of this disclosure.

[0013] Figure 4B This is an exemplary top view of a 2×2 photodiode group, representing yet another example of a trench balancing structure contained beneath a red color filter of a four-Bayer filter, according to the teachings of this disclosure.

[0014] Figure 5 The illustration depicts the center and edge regions of an exemplary pixel array comprising various examples of a trench balancing structure according to the teachings of this disclosure, the trench balancing structure being included together with at least some of a 2×2 photodiode group below the red color filter of a four-Bayer filter.

[0015] Several views throughout the drawings correspond to reference characters indicating the respective components. Those skilled in the art will understand that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, to aid in understanding the various embodiments of this disclosure, some elements in the figures may be enlarged relative to other elements. Additionally, common and well-known elements that are not typically depicted in commercially viable embodiments are shown to facilitate less obstructed observation of these various embodiments of this disclosure. Detailed Implementation

[0016] According to the teachings of this disclosure, exemplary patterns of trench balancing structures are described, which are incorporated below a color filter and together with a 2×2 group of photodiodes for sensing light having a wavelength greater than or equal to 600 nanometers, wherein a quad Bayer filter is disposed above a pixel array. Examples of quad Bayer filters may include, for example, red-green-green-blue (e.g., RGGB pattern) quad Bayer filter patterns, red-green-blue-infrared (e.g., RGB-IR pattern) quad Bayer filters, etc. Various examples of exemplary imaging systems with trench balancing structures are described herein, which are incorporated below a red color filter of a quad Bayer filter above a pixel array and together with a 2×2 group of photodiodes. In the following description, numerous specific details are set forth to provide a thorough understanding of the examples. However, those skilled in the art will recognize that the techniques described herein can be practiced without one or more of the specific details or can be practiced using other methods, components, materials, etc. In other examples, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring particular aspects.

[0017] Throughout this specification, references to "an example" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that example is included in at least one instance of this disclosure. Therefore, the appearance of the phrase "in an example" or "in an embodiment" in various places throughout this specification does not necessarily refer to the same example. Furthermore, the particular feature, structure, or characteristic may be combined in any suitable manner in one or more examples.

[0018] Spatially related terms (e.g., “below,” “under,” “above,” “below,” “over,” “top,” “upper,” “top,” “top,” “bottom,” “left,” “right,” “center,” “middle,” etc.) may be used herein for ease of description to describe the relationship of one element or feature relative to another element(s), as illustrated in the figures. It will be understood that, in addition to the orientations depicted in the figures, the spatially relative terms are intended to encompass different orientations of the device during use or operation. For example, if the device in the figures is rotated or flipped, then an element described as being “below,” “under,” or “below” other elements or features will then be oriented “above” those other elements or features. Therefore, the exemplary terms “below” and “below” can encompass both the above and below orientations. The device may be oriented in other ways (rotated 90 degrees or otherwise) and thus the spatially relative descriptions used herein will be understood. Furthermore, it will be understood that when an element is referred to as being “between” two other elements, the element may be the only element between the two other elements, or there may be one or more intervening elements.

[0019] Several technical terms are used throughout this specification. These terms will be given their general meaning in the field of their respective domains, unless otherwise specifically defined herein or the context in which they are used will clearly imply otherwise. It should be noted that component names and symbols are used interchangeably in this document (e.g., Si and silicon); however, they have the same meaning.

[0020] As will be discussed, various examples of imaging systems with a patterned groove balancing structure are disclosed, which is incorporated together with a group of 2×2 photodiodes below the red filter of a quad Bayer filter above the pixel array. An exemplary quad Bayer filter may comprise multiple minimal repeating units of a red filter, two green filters, and a blue filter repeating above the surface of the pixel array, thereby generating a red pixel, a green pixel, or a blue pixel at each corresponding pixel location.

[0021] In various instances, according to the teachings of this disclosure, a 2×2 group of photodiodes below the red color filter (R) is grouped with a green color filter (G) in the same row as the blue color filter. B (For example, green-blue (G) B The adjacent 2×2 photodiode group below the color filter and the green color filter (G) located in the same row as the red color filter. R (For example, green-red (G) R G between adjacent 2×2 photodiode groups below the color filter B G RThe signal crosstalk balancing is improved by the exemplary trench balancing structure according to the teachings of this disclosure through absorption, scattering, reflection, and / or refraction of light guided to the photodiode group below the red filter, thereby reducing the crosstalk of the green filter (G). B The 2×2 photodiode group below the red color filter (R) is adjacent to the green color filter (G). R The signal sensing difference between the 2×2 photodiode groups below.

[0022] As will be discussed, in various examples, a trench balancing structure is disposed in a semiconductor layer between a corresponding photodiode and a corresponding red filter in a four-Bayer color filter array (CFA). In examples, a trenchless balancing structure is disposed between either photodiode and a corresponding green or blue filter in a four-Bayer CFA. In various examples, each of the trench balancing structures extends from the central region of the corresponding opening in the isolation grid toward the center of the corresponding 2×2 photodiode group below the red filter. In some examples, the trench balancing structure is separated from the intersection point of the deep trench isolation (DTI) grid structure at the center of the corresponding 2×2 photodiode group by a center gap distance greater than or equal to zero. In other examples, each of the trench balancing structures extends from the central region of the corresponding opening in the isolation grid toward a first and a second side of the corresponding opening in the isolation grid of the 2×2 photodiode group below the red filter. In some examples, the trench balancing structure is separated from the first and a second side of the corresponding opening by a lateral gap distance greater than or equal to zero. In some instances, the trench balancing structure is structurally integrated with an internal DTI grid structure that provides isolation between photodiodes within a corresponding 2×2 photodiode group.

[0023] For illustration purposes, Figure 1The illustration depicts an example of a complementary metal-oxide-semiconductor (CMOS) imaging system 100 with an exemplary pattern of a trench-balanced structure according to the teachings of this disclosure, the trench-balanced structure being incorporated with a 2×2 photodiode group below a red color filter of a quad Bayer filter array above a pixel array. As shown in the depicted example, the imaging system 100 includes an image sensor with a pixel array 102, control circuitry 110, readout circuitry 106, and functional logic 108. In one example, the pixel array 102 is a two-dimensional (2D) array of pixel cells arranged in 2×2 photodiode groups. In this example, a quad Bayer color filter array (CFA) is disposed above a plurality of 2×2 photodiode groups on the back side of a semiconductor layer. The quad Bayer CFA includes a plurality of color filters, including a red color filter, a green color filter, and a blue color filter, wherein each color filter in the quad Bayer CFA is disposed above a corresponding one of the plurality of 2×2 photodiode groups. In the depicted example, the 2×2 photodiode group below the red filter is labeled 104R, the 2×2 photodiode group below the blue filter is labeled 104B, the 2×2 photodiode group below the green filter (e.g., the first green filter) in the same row as the red filter is labeled 104GR, and the 2×2 photodiode group below the green filter (e.g., the second green filter) in the same row as the blue filter is labeled 104GB. As will be discussed in more detail below, a plurality of trench balancing structures 114 are disposed in the semiconductor layer, wherein each of the plurality of trench balancing structures 114 is disposed in the semiconductor layer between a corresponding photodiode and a corresponding one of the red filters in the four Bayer CFA. In various examples, no trench balancing structure of the plurality of trench balancing structures 114 is disposed between any of the photodiodes and a corresponding green filter (G) in the four Bayer CFA. R and / or G B (or between blue filters)

[0024] In the depicted examples, photodiodes included in 2×2 photodiode groups 104R, 104B, 104GR, and 104GB are arranged in several rows and columns of pixel array 102 to acquire image data of people, places, objects, etc., which can then be used to reproduce images of people, places, objects, etc. As will be discussed, multiple deep trench isolation (DTI) grid structures are disposed in the semiconductor layer of pixel array 102 and arranged to form isolation grids in the semiconductor layer. Multiple openings are defined by the isolation grids, wherein each of the photodiodes is isolated within a corresponding one of the multiple openings defined in the isolation grids. In various examples, according to the teachings of this disclosure, the 2×2 photodiode group 104R below the red color filter (R) and the green color filter (G) in the same row as the blue color filter are... BBelow are adjacent 2×2 photodiode groups 104B (e.g., green-blue (G) B The adjacent 2×2 photodiode group below the color filter (104GB) and the green color filter (G) located in the same row as the red color filter. R The adjacent 2×2 photodiode groups below (e.g., green-red (G) R The G between adjacent 2×2 photodiode groups 104GR below the color filter B G R Signal crosstalk can be balanced by absorbing, scattering, reflecting and / or refracting light.

[0025] After the photodiodes included in the 2×2 photodiode groups 104R, 104B, 104GR, and 104GB have acquired their image charge, the corresponding analog image signal is read out by the readout circuit 106 via the bit line 112. In various instances, the readout circuit 106 includes an analog-to-digital converter (ADC) circuit coupled to convert the analog image signal received via the bit line 112 from the photodiodes included in the 2×2 photodiode groups 104R, 104B, 104GR, and 104GB into a digital image signal, which can then be transmitted to functional logic 108. Functional logic 108 can simply store the image data or even manipulate the image data by applying post-image processing or effects. For example, this image processing can include image processing, image filtering, image extraction and manipulation, determination of light intensity, cropping, rotation, red-eye removal, brightness adjustment, contrast adjustment, etc.

[0026] In one example, control circuitry 110 is coupled to pixel array 102 to control the operational characteristics of pixel array 102. For example, in one example, control circuitry 110 generates transfer gate signals and other control signals to control the transmission and readout of image data from all pixel units 104 of pixel array 102. Additionally, control circuitry 110 may generate shutter signals for controlling image acquisition. In one example, the shutter signal is a rolling shutter signal, causing each row of pixel array 102 to be read out sequentially row by row during a continuous acquisition window. The shutter signal may also establish an exposure time, which is the length of time the shutter remains open. In one embodiment, the exposure time is set to be the same for each element in the frame.

[0027] Figures 2A to 2B The diagram illustrates a 2×2 grouping of photodiodes with a pixel array having four Bayer filters, according to the teachings of this disclosure. Specifically, Figure 2A This is a top view illustrating an example of a group of adjacent 2×2 photodiodes below the red, green, and blue color filters of a four-Bayer filter in a pixel array 202. Figure 2B It is through the teachings of this disclosure Figure 2A An exemplary cross-sectional view of two photodiodes PD3 and PD4 in the 2×2 photodiode group 204R below the red filter 238 of the pixel array 202, through the dashed line A-A' and passing through the two trench balancing structures 214-3 and 214-4. It should be noted that... Figures 2A to 2B The exemplary 2×2 photodiode grouping illustrated in the figure can be: Figure 1 Examples of one or more of the 2×2 photodiode groups in the example pixel array 102, and it should be understood that similarly named and numbered elements referred to below are coupled and function as described above.

[0028] like Figure 2A As illustrated in the example, a 2×2 photodiode group 204B is positioned below the blue filter of the four-Bayer filter; a 2×2 photodiode group 204GB is positioned below the green filter in the same row as the blue filter; a 2×2 photodiode group 204R is positioned below the red filter of the four-Bayer filter; and a 2×2 photodiode group 204GR is positioned below the green filter in the same row as the red filter. In this example, the 2×2 photodiode group 204GR positioned below the green filter (e.g., the first green filter) is adjacent to a corresponding one of the 2×2 photodiode groups 204R positioned below the red filter in the same row. The 2×2 photodiode group 204GB positioned below the green filter (e.g., the second green filter) is adjacent to a corresponding one of the 2×2 photodiode groups 204B positioned below the blue filter in the same row. The 2×2 photodiode group 204GB located below the green filter (e.g., the second green filter) is adjacent to a corresponding one of the 2×2 photodiode groups 204R located below the red filter in the same column.

[0029] As illustrated in the depicted example, a plurality of DTI grid structures 216 are disposed in the semiconductor layer 236 near the rear side 234 and arranged to form an isolation grid in the semiconductor layer 236. In some embodiments, the semiconductor layer 236 is a silicon wafer or substrate, a silicon-germanium alloy, germanium, a silicon carbide alloy, an indium gallium arsenide alloy, any other alloy formed of group III-V compounds, other semiconductor materials or alloys, combinations thereof, or a bulk substrate. In some embodiments, the semiconductor layer 236 is an epitaxial layer grown on or otherwise disposed on a semiconductor substrate or wafer substrate. In the example, a plurality of openings are defined by the isolation grid 216. As shown, the rear side 234 of the semiconductor layer 236 is opposite to the front side 232 of the semiconductor layer 236. In this example, each of the photodiodes (e.g., PD1, PD2, PD3, PD4) is configured to be illuminated by incident light, which is guided through the back side 234 of the semiconductor layer 236 via a microlens 220 and a color filter (e.g., the illustrated red color filter 238). In the depicted example, the red color filter 238 is illustrated as being disposed in an opening of a metal grid 222, which is disposed above the filler material 224 and the outer-side DTI grid structure 216E, as will be described in more detail below. In various examples, the metal grid 222 helps provide optical isolation between adjacent 2×2 photodiode groups in the pixel array. For example, the metal grid 222 helps provide optical isolation between a 2×2 photodiode group below the red color filter 238 and an adjacent 2×2 photodiode group (e.g., 2×2 photodiode group 204GR or 204GB) below the green color filter. In various embodiments, microlens 220 is one of a plurality of microlenses included in a microlens array disposed above a four-Bayer filter on the rear side 234 of semiconductor layer 236. In one embodiment, a microlens is disposed above each 2×2 group of photodiodes or above each color filter in the four-Bayer filter. In another embodiment, each of the photodiodes is isolated within a corresponding one of a plurality of openings defined by isolation grid 216 in semiconductor layer 236.

[0030] In this example, a plurality of DTI gate structures 216 are disposed in a semiconductor layer 236, the plurality of DTI gate structures being arranged to form an isolation grid in the semiconductor layer. As shown in the depicted example, each of the plurality of DTI gate structures 216 is arranged to extend from the rear side 234 into the semiconductor layer 236 and to have a depth or gate structure depth D in the semiconductor layer 236 relative to the rear side 234 of the semiconductor layer 236. G The depth D in the embodiment GThe thickness of the semiconductor layer 236 may be less than or equal to that of the semiconductor layer 236, which may range from 2.5 micrometers to 7 micrometers. In one example, the DTI lattice structure 216 includes a filler material 224 disposed within the semiconductor layer 236. In another example, a high-k liner material 240 is disposed between the filler material 224 and the semiconductor layer 236. In one embodiment, the filler material 224 may be further disposed on the back side 234 of the semiconductor layer 236 to form a processing buffer layer that provides process protection for the underlying layer. In various examples, the filler material 224 may comprise a dielectric material, such as an oxide-based material, a low-n material, a conductive material (e.g., polysilicon, tungsten (W), aluminum (Al)), or other materials, or a combination of dielectric and conductive materials. A low-n material may refer to a material having a refractive index lower than that of the semiconductor layer 236. In various examples, the high-k liner material 240 may comprise a passivating material, an anti-reflective coating, etc. In various examples, the high-k lining material 240 may be composed of hafnium oxide, aluminum oxide, tantalum pentoxide, zinc oxide, etc.

[0031] In this example, each of the photodiodes (e.g., PD1, PD2, PD3, PD4) in each 2×2 photodiode group is isolated within a corresponding opening of a plurality of openings defined by an isolation grid formed by a DTI grid structure 216. For example, the isolation grid 216 may be arranged to provide electrical and / or optical isolation between the 2×2 photodiode group 204B and adjacent 2×2 photodiode groups (e.g., 2×2 photodiode group 204GR or 2×2 photodiode group 204GB). As shown in the example, each 2×2 photodiode group (e.g., 204B, 204GB, 204GR, 204R) is surrounded by an outer-side DTI grid structure 216E that forms a “square” shape around each 2×2 photodiode group. Additionally, an inner-side DTI grid structure 216I is formed within each 2×2 photodiode group. This inner-side DTI grid structure forms a "plus" shape and isolates each of the photodiodes (e.g., PD1, PD2, PD3, PD4) within the 2×2 photodiode group, which is within a "square" shape formed by the outer-side DTI grid structure 216E. In other embodiments, the DTI grid structure 216 can form different geometries, such as pentagons, octagons, triangles, and rectangles. As shown in the example, the center 218 of the corresponding 2×2 photodiode group is located at the intersection point of the orthogonal inner-side DTI grid structures 216I within each 2×2 photodiode group.

[0032] As illustrated in the depicted example, multiple trench balancing structures 214-1, 214-2, 214-3, and 214-4 are also disposed in the semiconductor layer. In this example, each of the multiple trench balancing structures (e.g., 214-1, 214-2, 214-3, and 214-4) is disposed in the semiconductor layer 236 between one of the photodiodes (e.g., PD1, PD2, PD3, and PD4) in the 2×2 photodiode group and a corresponding one of the red color filters 238 in the four-bay CFA. Furthermore, none of the multiple trench balancing structures (e.g., 214-1, 214-2, 214-3, and 214-4) is disposed between any of the photodiodes and a corresponding green or blue color filter in the four-bay CFA. Therefore, it should be understood that each of the multiple trench balancing structures (e.g., 214-1, 214-2, 214-3, 214-4) is disposed in a semiconductor layer between one of the multiple 2×2 photodiode groups (e.g., 204R) and a corresponding one of the red color filters, the 2×2 photodiode group being adjacent to another 2×2 photodiode group (e.g., 204GR) disposed under a green color filter (e.g., first green) in the same row of the pixel array.

[0033] As illustrated in the depicted example, each of the plurality of trench balancing structures (e.g., 214-1, 214-2, 214-3, 214-4) is arranged to extend from the rear side 234 into the semiconductor layer 236 and to have a depth or balancing structure depth D in the semiconductor layer 236 relative to the rear side 234 of the semiconductor layer 236. B In some embodiments, depth D B The depth is less than the corresponding depth of each of photodiodes PD1, PD2, PD3, and PD4 relative to the rear side 234 of semiconductor layer 236. In some embodiments, each of the plurality of trench balancing structures (e.g., 214-1, 214-2, 214-3, 214-4) may partially extend into the corresponding photodiode region of the corresponding photodiode PD1, PD2, PD3, PD4. That is, each of the plurality of trench balancing structures (e.g., 214-1, 214-2, 214-3, 214-4) may be partially surrounded by the corresponding photodiode region of the corresponding photodiode PD1, PD2, PD3, PD4. In various instances, color separation, processing, and G within the pixel unit are taken into consideration. B G R Balancing performance, depth D of trench balancing structures 214-1, 214-2, 214-3, and 214-4 B The depth D of the DTI lattice structure 216 in the semiconductor layer 236 is less than or equal to the depth D. GIn various instances, the depth D depends on the thickness of the semiconductor layer 236. B It can be in the range of 0.5μm to 2μm.

[0034] In one example, trench balancing structures 214-1, 214-2, 214-3, and 214-4 contain the same material as the DTI grid structure 216. For example, as shown in the depicted examples, trench balancing structures 214-1, 214-2, 214-3, and 214-4 include a filler material 224, which may comprise a dielectric material (e.g., an oxide-based material), a low-k material, a conductive material (e.g., polysilicon, tungsten (W), aluminum (Al)), or other materials, or a combination of dielectric and conductive materials. In various examples, a high-k liner material 240 is disposed between the filler material 224 and the semiconductor layer 236. In various examples, the high-k liner material 240 may comprise a passivating material, an anti-reflective coating, etc. In one embodiment, the trench balancing structures 214-1, 214-2, 214-3, and 214-4 are structurally connected to the DTI grid structure 216 (e.g., formed simultaneously in the same photolithography process sharing the same photomask).

[0035] In the examples 214-1, 214-2, 214-3, and 214-4, which do not have a trench balance structure below the red color filter, it should be understood that at the horizontal edge below the red light, crosstalk occurs primarily along the horizontal direction from the red color channel to the green-red G channel. R The color channel occurs, rather than from the red color channel to G. B Color channels occur, resulting in G values ​​that affect image quality. B G R Differences or imbalances. G B G R The difference can vary across multiple four pixels contained in the pixel array, and across the G of the pixel array. B G R This variation in difference occurs in relation to the principal ray angle. For example, a smaller or zero G can be found at the center of a pixel array where the principal ray angle is 0 degrees. B G R Differences, and G B G R The difference increases with the distance between the four pixels and the center of the pixel array (i.e., with the increase of the principal ray angle). However, according to the teachings of this disclosure, in the case of trench balance structures 214-1, 214-2, 214-3, 214-4 below the red color filter, the 2×2 photodiode group 204R and the green color filter (G R Below are adjacent 2×2 photodiode groups 204GR and green color filter (G) BBelow, the adjacent 2×2 photodiode groups 204GB are between G. B G R Signal crosstalk is balanced by absorbing, scattering, reflecting, and / or refracting light. That is, according to the teachings of this disclosure, by utilizing trench balancing structures 214-1, 214-2, 214-3, and 214-4 to absorb, scatter, reflect, and / or refract light guided to a 2×2 photodiode group below a red filter, the crosstalk between the 2×2 photodiode group 204R and the green filter (G) is improved. R Below are adjacent 2×2 photodiode groups 204GR and green color filter (G) B The signal difference between adjacent 2×2 photodiode groups 204GB below can be reduced.

[0036] Figure 3A This is an illustrated top view with increased detail of an example of a 2×2 photodiode group 304R, illustrating an example of a trench balance structure contained beneath a red color filter of a four-Bayer filter, according to the teachings of this disclosure. It should be noted that... Figure 3A The exemplary 2×2 photodiode group 304R illustrated in the diagram can be... Figures 2A to 2B The 2×2 photodiode grouping 204R of the example pixel array 202 Figure 1 Examples of 2×2 photodiode groups 104R in the example pixel array 102 are shown, and it should be understood that similarly named and numbered elements referred to below are coupled and function as described above.

[0037] As illustrated in the depicted example, the 2×2 photodiode group 304R comprises a 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4, which are contained within a pixel array and located below a red color filter of a quad Bayer filter positioned above the pixel array. In this example, the 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4 is isolated within or surrounded by the outer-side DTI grid structure 316E of the isolation grid 316. As shown, each of photodiodes PD1, PD2, PD3, and PD4 is isolated within a corresponding opening defined by the outer DTI grid structure 316E and the inner DTI grid structure 316I of the isolation grid 316. The center 318 of the 2×2 photodiode group 304R is located at the intersection of the orthogonal inner-side DTI grid structures (e.g., the inner DTI grid structure 316I) within the 2×2 photodiode group 304R. In the embodiment, the internal DTI grid structure 316I refers to a portion of the isolation grid 316, which provides isolation between 2×2 photodiode groups within the same four-pixel unit, while the external DTI grid structure 316E provides isolation between adjacent 2×2 photodiode groups.

[0038] As shown in the described examples, a plurality of trench balancing structures 314-1, 314-2, 314-3, 314-4 are disposed in a semiconductor layer. Each of the plurality of trench balancing structures 314-1, 314-2, 314-3, 314-4 is disposed in the semiconductor layer between a corresponding one of the photodiodes (e.g., PD1, PD2, PD3, PD4) and a corresponding one of the red color filters in the four Bayer CFAs. In various examples, each trench balancing structure 314-1, 314-2, 314-3, 314-4 extends from the central region 328-1, 328-2, 328-3, 328-4 of a corresponding opening in the isolation grid 316 toward the center 318 of the 2×2 photodiode group 304R. For example, as shown in the depicted instance, trench balancing structure 314-1 extends from central region 328-1 to center 318, trench balancing structure 314-2 extends from central region 328-2 to center 318, trench balancing structure 314-3 extends from central region 328-3 to center 318, and trench balancing structure 314-4 extends from central region 328-4 to center 318.

[0039] In various instances, for a 1μm pixel, each of the trench balancing structures 314-1, 314-2, 314-3, and 314-4 may have a length L of, for example, approximately 0.3μm to 0.5μm (e.g., the distance from the center 318 to the opposite end of the respective trench balancing structure). In various instances, each of the trench balancing structures 314-1, 314-2, 314-3, and 314-4 may have a length that varies depending on the distance of the respective pixel from the central region of the pixel array. In various instances, the width W or critical dimension of each of the trench balancing structures 314-1, 314-2, 314-3, and 314-4 may be less than or equal to the width of the DTI grid structures 316I and 316E. In various instances, the trench balancing structures 314-1, 314-2, 314-3, and 314-4 may be fabricated or formed using the same masks used to fabricate or form the DTI grid structures 316I and 316E, or may be fabricated or formed separately using different masks used to fabricate or form the DTI grid structures 316I and 316E.

[0040] In the depicted example, there is no gap or a center gap distance equal to zero between the trench balance structures 314-1, 314-2, 314-3, 314-4 and the inner side DTI grid structure 316I at the center 318.

[0041] Figure 3B This is an exemplary top view with increased detail of a 2×2 photodiode group 304R, illustrating another example of a trench balance structure contained below a red color filter of a four-Bayer filter, according to the teachings of this disclosure. It should be noted that... Figure 3B The exemplary 2×2 photodiode group 304R illustrated in the diagram can be... Figures 2A to 2B The 2×2 photodiode grouping 204R of the example pixel array 202 Figure 1 This is another example of the 2×2 photodiode group 104R of the exemplary pixel array 102, and it should be understood that similarly named and numbered elements referred to below are coupled and function as described above. It should be further understood that... Figure 3B Example of a 2×2 photodiode grouped with 304R and Figure 3A The 2×2 photodiode group 304R shares many similarities with the example.

[0042] For example, Figure 3BThe exemplary 2×2 photodiode group 304R depicted includes a 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4, which are contained within a pixel array and located below a common red filter of a quad Bayer filter disposed above the pixel array. The red filter of the quad Bayer filter is disposed between a single microlens (not illustrated) and the 2×2 photodiode group 304R. In the example, the 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4 is isolated within or surrounded by an outer-side DTI grid structure 316E. As shown, each of photodiodes PD1, PD2, PD3, and PD4 is isolated within a corresponding opening defined by the outer DTI grid structure 316E and the inner DTI grid structure 316I. The center 318 of the 2×2 photodiode group 304R is located at the intersection of the orthogonal inner-side DTI grid structures 316I within the 2×2 photodiode group 304R.

[0043] As illustrated in the depicted examples, a plurality of trench balancing structures 314-1, 314-2, 314-3, 314-4 are disposed in a semiconductor layer. Each of the plurality of trench balancing structures 314-1, 314-2, 314-3, 314-4 is disposed in the semiconductor layer between a corresponding one of the photodiodes (e.g., PD1, PD2, PD3, PD4) and a corresponding one of the red color filters in the four Bayer CFAs. In various examples, each trench balancing structure 314-1, 314-2, 314-3, 314-4 extends from the central region 328-1, 328-2, 328-3, 328-4 of a corresponding opening in the isolation grid 316 toward the center 318 of the 2×2 photodiode group 304R. For example, as shown in the depicted instance, trench balancing structure 314-1 extends from central region 328-1 toward center 318, trench balancing structure 314-2 extends from central region 328-2 toward center 318, trench balancing structure 314-3 extends from central region 328-3 toward center 318, and trench balancing structure 314-4 extends from central region 328-4 toward center 318.

[0044] In various instances, for a 1μm pixel, each of the trench balancing structures 314-1, 314-2, 314-3, and 314-4 may have a length, for example, approximately 0.3μm to 0.5μm (e.g., the distance between opposite ends of the trench balancing structures 314-1, 314-2, 314-3, and 314-4). In various instances, each of the trench balancing structures 314-1, 314-2, 314-3, and 314-4 may have a length that varies depending on the distance of the respective pixel from the central region of the pixel array. In various instances, the width or critical dimension of each of the trench balancing structures 314-1, 314-2, 314-3, and 314-4 may be less than or equal to the width of the DTI grid structures 316I and 316E. In various instances, the trench balance structures 314-1, 314-2, 314-3, and 314-4 can be fabricated or formed using the same masks used to fabricate or form the DTI grid structures 316I and 316E, or they can be fabricated or formed separately using different masks (for example, for different trenches).

[0045] Figure 3B Example of a 2×2 photodiode grouped with 304R and Figure 3A One of the differences between the exemplary 2×2 photodiode groups 304R is that, Figure 3B In the exemplary 2×2 photodiode group 304R shown, there is a gap or a center gap distance greater than zero between the intersection points of the trench balancing structures 314-1, 314-2, 314-3, 314-4 and the inner-side DTI grid structure 316I at the center 318. For example, in Figure 3B In the examples depicted, there is a center gap distance 330-1 between the trench balancing structure 314-1 and the center 318, a center gap distance 330-2 between the trench balancing structure 314-2 and the center 318, a center gap distance 330-3 between the trench balancing structure 314-3 and the center 318, and a center gap distance 330-4 between the trench balancing structure 314-4 and the center 318. In various examples, the center gap distances 330-1, 330-2, 330-3, and 330-4 may be, for example, approximately 0.2 μm. In various examples, the minimum center gap distances 330-1, 330-2, 330-3, and 330-4 may be determined based on processing design rules and the size of the corresponding pixels. In various examples, the smaller the center gap distances 330-1, 330-2, 330-3, and 330-4, the better for G... B G R The better the improvement in the differences.

[0046] Figure 4AThis is an exemplary top view with increased detail of a 2×2 photodiode group 404R, illustrating yet another example of a trench balancing structure contained below a red color filter of a four-Bayer filter, according to the teachings of this disclosure. It should be noted that... Figure 4A The exemplary 2×2 photodiode group 404R illustrated in the diagram can be... Figures 2A to 2B The 2×2 photodiode grouping 204R of the example pixel array 202 Figure 1 This is yet another example of the 2×2 photodiode group 104R of the exemplary pixel array 102, and it should be understood that similarly named and numbered elements referred to below are coupled and function as described above. In this example, a red color filter of a four-Bayer filter is positioned between a single microlens (not illustrated) and the 2×2 photodiode group 404R.

[0047] As illustrated in the depicted example, the 2×2 photodiode group 404R comprises a 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4, which are contained within a pixel array and located below a red color filter of a quad Bayer filter positioned above the pixel array. In this example, the 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4 is isolated within or surrounded by an outer-side DTI grid structure 416E. As shown, each of photodiodes PD1, PD2, PD3, and PD4 is isolated within a corresponding opening defined by the outer DTI grid structure 416E and the inner DTI grid structure 416I. The center 418 of the 2×2 photodiode group 404R is located at the intersection of the orthogonal inner-side DTI grid structures 416I within the 2×2 photodiode group 404R.

[0048] As shown in the described example, a plurality of trench balancing structures 414-1, 414-2, 414-3, 414-4 are disposed in a semiconductor layer. Each of the plurality of trench balancing structures 414-1, 414-2, 414-3, 414-4 is disposed in the semiconductor layer between a corresponding one of the photodiodes (e.g., PD1, PD2, PD3, PD4) and a corresponding one of the red color filters in the four Bayer CFAs. As shown, each trench balancing structure 414-1, 414-2, 414-3, 414-4 has a first end 415 and a second end 417 opposite to the first end. In various examples, the first end 415 of each trench balancing structure 414-1, 414-2, 414-3, 414-4 extends from the corresponding central region 428-1, 428-2, 428-3, 428-4 of the corresponding opening in the isolation grid toward the first side 419 of the corresponding opening in the isolation grid. In the depicted example, the sides (e.g., 419, 421) of the corresponding opening in the isolation grid form an internal DTI grid structure 416I as shown. Continuing with the example, the second end 417 (opposite to the first end 415) of each trench balancing structure 414-1, 414-2, 414-3, 414-4 extends from the corresponding central region 428-1, 428-2, 428-3, 428-4 of the corresponding opening in the isolation grid toward the second side 421 of the corresponding opening in the isolation grid. In the depicted example, the first side 419 and the second side 421 of the corresponding opening in the isolation grid are orthogonal internal DTI grid structures 416I and intersect at the center 418 as shown. In the depicted example, each of the plurality of trench balancing structures 414-1, 414-2, 414-3, 414-4 and the corresponding internal DTI grid structure 416I can form a triangle within the corresponding opening in the isolation grid 416.

[0049] In various instances, for a 1μm pixel, each of the trench balancing structures 414-1, 414-2, 414-3, and 414-4 may have a length, for example, approximately 0.3μm to 0.5μm (e.g., the distance between the first end 415 and the second end 417). In various instances, each of the trench balancing structures 414-1, 414-2, 414-3, and 414-4 may have a length that varies depending on the distance of the respective pixel from the central region of the pixel array. In various instances, the width or critical dimension of each of the trench balancing structures 414-1, 414-2, 414-3, and 414-4 may be less than or equal to the width of the DTI grid structures 416I and 416E. In various instances, the trench balance structures 414-1, 414-2, 414-3, and 414-4 can be fabricated or formed using the same or different masks as those used to fabricate or form the DTI grid structures 416I and 416E.

[0050] In the depicted example, there is no gap or a lateral gap distance equal to zero between the trench balance structures 414-1, 414-2, 414-3, 414-4 and the inner side DTI grid structure 416I.

[0051] Figure 4B This is an exemplary top view with increased detail of a 2×2 photodiode group 404R, illustrating yet another example of a trench balancing structure contained beneath a red color filter of a four-Bayer filter, according to the teachings of this disclosure. It should be noted that... Figure 4B The exemplary 2×2 photodiode group 404R illustrated in the diagram can be... Figures 2A to 2B The 2×2 photodiode grouping 204R of the example pixel array 202 Figure 1 This is yet another example of the 2×2 photodiode group 104R of the exemplary pixel array 102, and it should be understood that similarly named and numbered elements referred to below are coupled and function as described above. It should be further understood that... Figure 4B Example of a 2×2 photodiode grouped 404R with Figure 4A The 2×2 photodiode group 404R shares many similarities with the example.

[0052] For example, Figure 4B The exemplary 2×2 photodiode group 404R depicted includes a 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4, which are contained within a pixel array and located below a red color filter of a quad Bayer filter positioned above the pixel array. In this example, the 2×2 arrangement of photodiodes PD1, PD2, PD3, and PD4 is isolated within or surrounded by an outer-side DTI grid structure 416E of an isolation grid 416. As shown, each of photodiodes PD1, PD2, PD3, and PD4 is isolated within a corresponding opening defined by the outer DTI grid structure 416E and the inner DTI grid structure 416I of the isolation grid 416. The center 418 of the 2×2 photodiode group 404R is located at the intersection of the orthogonal inner-side DTI grid structures 416I within the 2×2 photodiode group 404R.

[0053] As shown in the described example, a plurality of trench balancing structures 414-1, 414-2, 414-3, 414-4 are disposed in a semiconductor layer. Each of the plurality of trench balancing structures 414-1, 414-2, 414-3, 414-4 is disposed in the semiconductor layer between a corresponding one of the photodiodes (e.g., PD1, PD2, PD3, PD4) and a corresponding one of the red color filters in the four Bayer CFAs. As shown, each trench balancing structure 414-1, 414-2, 414-3, 414-4 has a first end 415 and a second end 417 opposite to the first end 415. In various examples, the first end 415 of each trench balancing structure 414-1, 414-2, 414-3, 414-4 extends from the corresponding central region 428-1, 428-2, 428-3, 428-4 of the corresponding opening in the isolation grid toward the first side 419 of the corresponding opening in the isolation grid 416. In the depicted example, the sides (e.g., 419, 421) of the corresponding opening in the isolation grid 416 are formed as shown in the internal DTI grid structure 416I. Continuing with the example, the second end 417 (opposite to the first end 415) of each trench balancing structure 414-1, 414-2, 414-3, 414-4 extends from the corresponding central region 428-1, 428-2, 428-3, 428-4 of the corresponding opening in the isolation grid 416 toward the second side 421 of the corresponding opening in the isolation grid 416. In the depicted example, the first side 415 and the second side 417 of the corresponding opening in the isolation grid 416 are orthogonal internal DTI grid structures 416I and intersect at the center 418 as shown.

[0054] In various instances, for a 1μm pixel, each of the trench balancing structures 414-1, 414-2, 414-3, and 414-4 may have a length, for example, approximately 0.3μm to 0.5μm (e.g., the distance between opposite ends of the trench balancing structures 414-1, 414-2, 414-3, and 414-4). In various instances, each of the trench balancing structures 414-1, 414-2, 414-3, and 414-4 may have a length that varies depending on the distance of the respective pixel from the central region of the pixel array. In various instances, the width or critical dimension of each of the trench balancing structures 414-1, 414-2, 414-3, and 414-4 may be less than or equal to the width of the DTI grid structures 416I and 416E. In various instances, the trench balance structures 414-1, 414-2, 414-3, and 414-4 can be fabricated or formed using the same or different masks as those used to fabricate or form the DTI grid structures 416I and 416E.

[0055] Figure 4B Example of a 2×2 photodiode grouped 404R with Figure 4A One of the differences between the exemplary 2×2 photodiode groups 404R is that, Figure 4B In the exemplary 2×2 photodiode group 404R shown, there is a gap or a greater than zero lateral gap distance between the first end 415 and the second end 417 of the trench balancing structures 414-1, 414-2, 414-3, 414-4 and the corresponding inner sides 419, 421 where the DTI grid structure 416I is formed. For example, in Figure 4B In the examples depicted, there is a lateral gap distance 430-1 between the first end 415 and the second end 417 of the trench balancing structure 414-1 and the corresponding inner sides 419 and 421 of the DTI grid structure 416I; there is a lateral gap distance 430-2 between the first end 415 and the second end 417 of the trench balancing structure 414-2 and the corresponding inner sides 419 and 421 of the DTI grid structure 416I; there is a lateral gap distance 430-3 between the first end 415 and the second end 417 of the trench balancing structure 414-3 and the corresponding inner sides 419 and 421 of the DTI grid structure 416I; and there is a lateral gap distance 430-4 between the first end 415 and the second end 417 of the trench balancing structure 414-4 and the corresponding inner sides 419 and 421 of the DTI grid structure 416I. In various instances, the lateral clearance distances 430-1, 430-2, 430-3, and 430-4 can be, for example, approximately 0.2 μm. In various instances, the minimum lateral clearance distances 430-1, 430-2, 430-3, and 430-4 can be determined based on processing design rules. In various instances, the smaller the center clearance distances 430-1, 430-2, 430-3, and 430-4, the better for G... B G R The better the improvement in the differences.

[0056] Figure 5 The diagram illustrates the center and edge regions of an exemplary pixel array 502 comprising various embodiments of a trench balancing structure according to the teachings of this disclosure, said trench balancing structure being included together with at least some of the 2×2 photodiode groups below the red filter of a four-Bayer filter. It should be noted that... Figure 5 The exemplary pixel array 502 illustrated in the figure can be Figure 1 Another example of pixel array 102, and it should be understood that similarly named and numbered elements referred to below are coupled and function as described above.

[0057] like Figure 5As illustrated in the example depicted, pixel array 502 includes a central region 502C and end or edge regions, which include a top edge region 502T, a bottom edge region 502B, a left edge region 502L, and a right edge region 502R. The central region 502C and edge regions 502T, 502B, 502L, and 502R of pixel array 502 can be defined according to a field of view, which is related to the size of pixel array 502 and the image height of an object. In one embodiment, the central region 502C can be defined as the imaging region of pixel array 502 located between the central field of view and a 0.05 field of view, and the peripheral region can be defined as the imaging region of pixel array 502 greater than a 0.05 field of view. In the example, pixel array 502 is a two-dimensional (2D) array of pixel units arranged in 2×2 photodiode groups, including a quad Bayer color filter array (CFA) disposed above a plurality of 2×2 photodiode groups. The four Bayer CFA includes a red, green, and blue color filter, with each color filter positioned above a corresponding group of 2×2 photodiodes. In the depicted example, the 2×2 photodiode group below the red color filter is labeled 504R, the 2×2 photodiode group below the blue color filter is labeled 504B, the 2×2 photodiode group below the green color filter in the same row as the red color filter is labeled 504GR, and the 2×2 photodiode group below the green color filter in the same row as the blue color filter is labeled 504GB. The 2×2 photodiode group 504R below the red color filter can be positioned adjacent to the 2×2 photodiode group below the green color filter in both row and column directions.

[0058] In various examples, such as the multiple trench balancing structures 514A, 514B described in detail above, the photodiodes are arranged in a 2×2 group within the semiconductor layer between the corresponding photodiode and the corresponding red color filter in the four-Bayer CFA. In various examples, none of the multiple trench balancing structures 514A, 514B are arranged between either the photodiode and the corresponding green color filter (G) in the four-Bayer CFA. R and / or G B ( ) or between blue color filters. In some instances, it should be understood that some of the 2×2 photodiode groups below the red color filter in a quad Bayer CFA may or may not include the corresponding trench balancing structures 514A, 514B.

[0059] For example, such as Figure 5As illustrated in the example, the 2×2 photodiode group below the red filter in the central region 502C of pixel array 202 does not include trench balancing structures 514A, 514B. Specifically, it should be understood that at the central region 502C of pixel array 502, the principal ray angle (CRA) of the incident light is zero degrees. Thus, there is no G. B G R The difference and therefore the need for trench balancing structures 514A and 514B to balance any G B G R The difference allows the central region 502C to have better color separation for the 2×2 photodiode group below the red filter (quad pixel unit), because the trench balancing structures 514A, 514B can cause uneven sensitivity in the corresponding 2×2 photodiode group. However, towards the edge regions of the pixel array 502 (e.g., in the top region 502T, bottom region 502B, left region 502L, and right region 502R), CRA increases, which increases the usefulness of the trench balancing structures 514A, 514B. Thus, as shown in the depicted example, the trench balancing structures 514A, 514B are included in the 2×2 photodiode group below the red filter in the edge regions of the pixel array 502 (e.g., in the top region 502T, bottom region 502B, left region 502L, and right region 502R). In some embodiments, the trench balancing structures 514A, 514B can be included in the 2×2 photodiode group below the red filter, given G. B G R The difference level and color separation level determine the arrangement (number and position) of the trench balance structures 514A and 514B across the pixel array for the red filter.

[0060] However, it should be understood that in some embodiments, it may be desirable to have the same trench balancing structure, such as the trench balancing structure 514A contained in each of the 2×2 photodiode groups below the red color filter across the pixel array.

[0061] In various instances, it should be understood that the structural parameters of one or more of the width, length, depth, center-to-center gap distance, and lateral gap distance of the trench balancing structures 514A, 514B contained in the 2×2 photodiode group below the red filter can be based on the required G B G R The balance and improved color separation vary across the pixel array 202. Therefore, it should be understood that the types of trench balance structures 514A and 514B can also vary across the pixel array 502. For example, such as... Figure 5 The trench balancing structure 514A illustrated in the examples depicted is similar to... Figure 3AThe trench balancing structure described in the example, and the trench balancing structure illustrated in Figure 514B are similar to Figure 3B The trench balancing structure is an example described herein. In various examples, the length of each of the trench balancing structures 514A, 514B may depend on the position of the red pixel relative to the central region 502C and the associated G. B G R Different configurations are made due to differences. It should be further understood that the trench balancing structure included in the 2×2 photodiode group may contain... Figure 2A , 3A Any combination of structures or trench balance structures illustrated in 3B, 4A, and 4B, depending on pixel size, pixel array placement, color separation performance, and / or G B G R Level of difference.

[0062] The above description of the illustrated examples of this disclosure, including the content described in the abstract, is not intended to be exhaustive or to limit the examples of this disclosure to the precise form disclosed. Although specific examples of this disclosure have been described herein for illustrative purposes, various modifications will be recognized by those skilled in the art within the scope of this disclosure.

[0063] These modifications may be made to the examples of this disclosure in light of the detailed description above. The terminology used in the appended claims should not be construed as limiting the examples of this disclosure to the specific examples disclosed in this specification. Rather, the scope of the examples of this disclosure will be determined entirely by the appended claims, which will be interpreted in accordance with the established principles of claim interpretation.

Claims

1. A pixel array comprising: Multiple 2×2 photodiode groups are located in a semiconductor layer to generate image charge in response to incident light guided through the rear side of the semiconductor layer; A quad Bayer color filter array is disposed on the rear side of the semiconductor layer above the plurality of 2×2 photodiode groups, wherein the quad Bayer color filter array includes a plurality of color filters, wherein the plurality of color filters includes a red color filter, a green color filter and a blue color filter, wherein each color filter in the quad Bayer color filter array is disposed above a corresponding one of the plurality of 2×2 photodiode groups. and Multiple trench balancing structures are disposed in the semiconductor layer, wherein each of the multiple trench balancing structures is disposed in the semiconductor layer between one of the photodiodes and a corresponding one of the red color filters in the four Bayer color filter array, wherein none of the multiple trench balancing structures is disposed between any of the photodiodes and a corresponding green or blue color filter in the four Bayer color filter array.

2. The pixel array of claim 1, further comprising a plurality of deep trench isolation grid structures disposed in the semiconductor layer and arranged to form an isolation grid in the semiconductor layer, wherein a plurality of openings are defined by the isolation grid, wherein each of the photodiodes is isolated within a corresponding one of the plurality of openings defined by the isolation grid.

3. The pixel array of claim 2, wherein the plurality of trench balancing structures comprises trench balancing structures extending from the central region of a corresponding opening in the isolation grid toward the center of a corresponding 2×2 photodiode group.

4. The pixel array according to claim 3, wherein the intersection point of the trench balancing structure and the deep trench isolation grid structure located at the center of the corresponding 2×2 photodiode group is separated by a central gap distance.

5. The pixel array according to claim 4, wherein the center gap distance is zero.

6. The pixel array of claim 2, wherein the plurality of trench balancing structures comprises a trench balancing structure having a first end opposite to a second end, wherein the first end extends from a central region of a corresponding opening in the isolation grid toward a first side of the corresponding opening in the isolation grid, wherein the second end extends from the central region of the corresponding opening in the isolation grid toward a second side of the corresponding opening in the isolation grid, wherein the first side and the second side of the corresponding opening in the isolation grid intersect the center of a corresponding 2×2 photodiode group.

7. The pixel array of claim 6, wherein the first end and the second end of the trench balancing structure are separated from the first side and the second side of the corresponding opening in the isolation grid by a lateral gap distance.

8. The pixel array according to claim 7, wherein the lateral gap distance is zero.

9. The pixel array according to claim 2, wherein the plurality of trench balancing structures and the plurality of deep trench isolation grid structures comprise: A filling material disposed within the semiconductor layer; and A high-k lining material is disposed between the filler material and the semiconductor layer.

10. The pixel array according to claim 2, wherein the balance structure depth of the plurality of trench balance structures is less than or equal to the grid structure depth of the plurality of deep trench isolation grid structures.

11. The pixel array of claim 1, further comprising a microlens array disposed on the rear side of the semiconductor layer above the plurality of 2×2 photodiode groups, wherein each microlens in the microlens array is disposed above a corresponding one of the plurality of 2×2 photodiode groups.

12. The pixel array of claim 1, wherein the grooveless balancing structure is disposed in the central region of the pixel array.

13. The pixel array of claim 12, wherein each of the plurality of trench balancing structures is disposed in an edge region of the pixel array.

14. The pixel array of claim 1, wherein each of the plurality of trench balancing structures is disposed in the semiconductor layer between one of the plurality of 2×2 photodiode groups and the corresponding one of the red color filters, the corresponding one of the red color filters being adjacent to another 2×2 photodiode group, the other 2×2 photodiode group being disposed under one of the green color filters in the same row of the pixel array.

15. The pixel array of claim 1, wherein the structural parameters of one or more of the width, length, depth, center gap distance, and lateral gap distance of each of the plurality of trench balancing structures vary across the pixel array.

16. An imaging system comprising: A pixel array comprising: Multiple 2×2 photodiode groups are located in a semiconductor layer to generate image charge in response to incident light guided through the rear side of the semiconductor layer; A quad Bayer color filter array is disposed on the rear side of the semiconductor layer above the plurality of 2×2 photodiode groups, wherein the quad Bayer color filter array includes a plurality of color filters, wherein the plurality of color filters includes a red color filter, a green color filter and a blue color filter, wherein each color filter in the quad Bayer color filter array is disposed above a corresponding one of the plurality of 2×2 photodiode groups. and Multiple trench balancing structures are disposed in the semiconductor layer, wherein each of the multiple trench balancing structures is disposed in the semiconductor layer between one of the photodiodes and a corresponding one of the red color filters in the four Bayer color filter array, wherein none of the multiple trench balancing structures is disposed between any of the photodiodes and a corresponding green or blue color filter in the four Bayer color filter array; A control circuit system coupled to the pixel array to control the operation of the pixel array; as well as A readout circuitry system coupled to the pixel array to read out image data from the pixel array.

17. The imaging system of claim 16, further comprising functional logic coupled to the readout circuitry to store the image data read from the pixel array.

18. The imaging system of claim 16, wherein the pixel array further comprises a plurality of deep trench isolation grid structures disposed in the semiconductor layer and arranged to form an isolation grid in the semiconductor layer, wherein a plurality of openings are defined by the isolation grid, wherein each of the photodiodes is isolated within a corresponding one of the plurality of openings defined by the isolation grid.

19. The imaging system of claim 18, wherein the plurality of trench balancing structures comprises trench balancing structures extending from the central region of a corresponding opening in the isolation grid toward the center of a corresponding 2×2 photodiode group.

20. The imaging system of claim 19, wherein the trench balancing structure is separated from the center gap distance by the intersection point of the deep trench isolation grid structure located at the center of the corresponding 2×2 photodiode group.

21. The imaging system of claim 20, wherein the center gap distance is zero.

22. The imaging system of claim 18, wherein the plurality of trench balancing structures comprises a trench balancing structure having a first end opposite to a second end, wherein the first end extends from a central region of a corresponding opening in the isolation grid toward a first side of the corresponding opening in the isolation grid, wherein the second end extends from the central region of the corresponding opening in the isolation grid toward a second side of the corresponding opening in the isolation grid, wherein the first side and the second side of the corresponding opening in the isolation grid intersect the center of a corresponding 2×2 photodiode group.

23. The imaging system of claim 22, wherein the first end and the second end of the groove balancing structure are separated from the first side and the second side of the corresponding opening in the isolation grid by a lateral gap distance.

24. The imaging system of claim 23, wherein the lateral gap distance is zero.

25. The imaging system of claim 18, wherein the plurality of trench balancing structures and the plurality of deep trench isolation grid structures comprise: A filling material disposed within the semiconductor layer; and A high-k lining material is disposed between the filler material and the semiconductor layer.

26. The imaging system of claim 18, wherein the balance structure depth of the plurality of trench balance structures is less than or equal to the grid structure depth of the plurality of deep trench isolation grid structures.

27. The imaging system of claim 16, wherein the pixel array further comprises a microlens array disposed on the rear side of the semiconductor layer above the plurality of 2×2 photodiode groups, wherein each microlens in the microlens array is disposed above a corresponding one of the plurality of 2×2 photodiode groups.

28. The imaging system of claim 16, wherein the grooveless balancing structure is disposed in the central region of the pixel array.

29. The imaging system of claim 28, wherein each of the plurality of trench balancing structures is disposed in an edge region of the pixel array, wherein the edge region surrounds the central region.

30. The imaging system of claim 16, wherein each of the plurality of trench balancing structures is disposed in the semiconductor layer between one of the plurality of 2×2 photodiode groups and the corresponding one of the red color filters, the corresponding one of the red color filters being adjacent to another 2×2 photodiode group, the other 2×2 photodiode group being disposed under one of the green color filters in the same row of the pixel array.

Images