Image sensor
By introducing a four-quadrant phase sensing unit (QPD) into a solid-state image sensor and employing an optical element design with a ring lens and a central lens, the scattering and noise problems caused by light focusing on the deep trench isolation structure are solved, thereby improving the light reception uniformity and efficiency of the photodiode.
Patent Information
- Application Number
- CN202411475038.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-06-21
- Filing Date
- 2024-10-22
- Publication Date
- 2025-12-23
AI Technical Summary
Traditional solid-state image sensors tend to focus on deep trench isolation structures when long-wavelength light is incident, leading to increased scattering and noise, which affects the uniformity and efficiency of light reception of photodiodes.
The design employs a four-quadrant phase sensing unit (QPD) and includes four photodiodes, a deep trench isolation structure, a grid, a color filter, and optical elements. The optical elements consist of a ring lens and a central lens. The ring lens is partially superimposed on the outer wall of the deep trench isolation structure and is designed to compensate for alignment misalignment of the optical elements and changes in the incident light angle.
It improves the light reception imbalance problem of QPD cells, enhances the light reception uniformity and efficiency of photodiodes, and significantly improves L/R balance and quantum efficiency, especially in the presence of alignment errors and incident light angle variations.
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Figure CN121194535A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to an image sensor. Background Technology
[0002] Image sensing devices are widely used in various image capturing equipment, such as digital camcorders and digital cameras. Generally, solid-state image sensors, such as charge-coupled device (CCD) sensors or complementary metal-oxide-semiconductor (CMOS) sensors, are sensors with photoelectric converters, such as photodiodes, used to convert light into electrical charges. Photodiodes are formed on a semiconductor substrate, such as a silicon wafer. The electrical signals corresponding to photons generated by the photodiode can be further processed by CCD or CMOS readout circuits.
[0003] In traditional solid-state image sensors with a multi-photodiode architecture (i.e., a single color filter corresponding to two, four, or more photodiodes), when longer wavelengths of light enter the solid-state image sensor, they tend to focus on the deep trench isolation structure, leading to strong scattering and noise. Therefore, there is still much room for improvement in the field of solid-state image sensor technology. Summary of the Invention
[0004] One embodiment of this disclosure provides an image sensor including a first four-quadrant phase detection (QPD) unit comprising four photodiodes, a deep trench isolation structure, a grid, a color filter, and optical elements. The photodiodes are arranged in a two-column by two-row array. The deep trench isolation structure includes an outer wall surrounding the photodiodes and an inner wall separating the photodiodes. The grid is disposed on the deep trench isolation structure. The color filter is disposed on the photodiodes and fills the grid. The optical elements are disposed on the color filters and include an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.
[0005] In some embodiments, the annular lens and the central lens are made of the same material, and the refractive index of the annular lens and the central lens is between 1.5 and 2.5.
[0006] In some embodiments, the height of the annular lens is less than the height of the central lens, and the size of the annular lens is less than the size of the central lens.
[0007] In some embodiments, the ratio between the height of the annular lens and the height of the central lens is between 45% and 65%.
[0008] In some embodiments, the ratio between the size of the annular lens and the color spacing size is between 14% and 25%, wherein the color spacing size is the distance between the centers of two opposite portions of the grid.
[0009] In some embodiments, the outer tangent of the annular lens is aligned with the long axis of the outer wall of the deep trench isolation structure.
[0010] In some embodiments, the outer tangent of the annular lens is offset relative to the major axis of the outer wall of the deep trench isolation structure, and the offset between the outer tangent of the annular lens and the major axis of the outer wall of the deep trench isolation structure is equal to or less than 50 nm.
[0011] In some embodiments, the shape of the outer contour of the annular lens is the same as the shape of the inner contour of the annular lens.
[0012] In some embodiments, the shape of the outer contour of the annular lens is different from the shape of the inner contour of the annular lens.
[0013] In some embodiments, the central lens is superimposed on the photodiode.
[0014] In some embodiments, a central lens is superimposed on two of the photodiodes, and the image sensor further includes another optical element disposed on a color filter and superimposed on two other photodiodes. This other optical element includes an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens of the other optical element are superimposed on the outer wall of the deep trench isolation structure.
[0015] In some embodiments, the image sensor further includes a second QPD unit comprising four photodiodes, a deep trench isolation structure, a grid, a color filter, and optical elements. The photodiodes are arranged in a two-column by two-row array. The deep trench isolation structure includes an outer wall surrounding the photodiodes and an inner wall separating the photodiodes. Color filters are disposed on the photodiodes, wherein the filtering band of the color filter in the second QPD unit differs from the filtering band of the color filter in the first QPD unit. Optical elements are disposed on the color filters.
[0016] In some embodiments, the optical elements of the second QPD unit include an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.
[0017] In some embodiments, the annular lens of the first QPD unit is connected in parallel with the annular lens of the second QPD unit.
[0018] In some embodiments, the shape of the optical element of the first QPD unit is different from the shape of the optical element of the second QPD unit.
[0019] In some embodiments, the fill factor of the annular lens of the first QPD unit is different from the fill factor of the annular lens of the second QPD unit.
[0020] In some embodiments, the optical elements of the second QPD unit include four ball lenses, each disposed on a photodiode.
[0021] In some embodiments, the optical element of the second QPD unit includes a single spherical lens disposed on the photodiode.
[0022] In some embodiments, the image sensor further includes a second QPD unit comprising four photodiodes, a deep trench isolation structure, a grid, a color filter, a first optical element, and a second optical element. The photodiodes are arranged in a two-column by two-row array. The deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiodes and the inner wall separating the photodiodes. A color filter is disposed on the photodiodes, wherein the filtering band of the color filter of the second QPD unit differs from the filtering band of the color filter of the first QPD unit. The first optical element is disposed on the color filter and on two adjacent photodiodes, the first optical element comprising an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure. The second optical element is disposed on the color filter and on two other photodiodes, the second optical element comprising an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.
[0023] In some embodiments, the image sensor further includes a second QPD unit comprising four photodiodes, a deep trench isolation structure, a grid, a color filter, and four optical elements. The photodiodes are arranged in a two-column by two-row array. The deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiodes and the inner wall separating the photodiodes. Color filters are disposed on the photodiodes, wherein the filtering band of the color filter of the second QPD unit differs from the filtering band of the color filter of the first QPD unit. Optical elements are disposed on the color filters and respectively located on the photodiodes, each optical element including an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.
[0024] The optical element of the QPD unit in the image sensor provided in this disclosure includes an annular lens and a central lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure, allowing the optical element to provide more than one focal point on the photodiode, thereby improving the L / R balance of the QPD unit. Attached Figure Description
[0025] To make the objectives, features, advantages, and embodiments of this disclosure more apparent and understandable, the detailed description of the accompanying drawings is as follows:
[0026] Figure 1 This is a cross-sectional view of a portion of an image sensor according to some embodiments of the present disclosure.
[0027] Figure 2 This is a top view of a quadrature phase detection (QPD) unit of an image sensor according to some embodiments of the present disclosure.
[0028] Figure 3A as well as Figure 3B These are cross-sectional views and top views of the QPD unit of an image sensor according to some embodiments of this disclosure.
[0029] Figure 4A as well as Figure 4B These are cross-sectional views and top views of the QPD unit of an image sensor according to other embodiments of this disclosure.
[0030] Figure 5A This is a top view of an existing QPD cell with alignment error. Figure 5B This is a schematic diagram of the operation of an existing QPD cell with alignment error, wherein... Figure 5B For along Figure 5A It cuts through the diagonal.
[0031] Figure 5C This is a top view of a QPD cell with alignment error according to an embodiment of the present disclosure.
[0032] Figure 5D This is a schematic diagram of the operation of a QPD unit according to an embodiment of the present disclosure, wherein... Figure 5D For along Figure 5C It cuts through the diagonal.
[0033] Figures 6A to 6F This is a top view of a QPD unit according to different embodiments of the present disclosure.
[0034] Figures 7A to 7I This is a top view of a group of QPD units according to different embodiments of the present disclosure.
[0035] Figures 8A to 8DThis is a top view of an image sensor according to different embodiments of the present disclosure.
[0036] The reference numerals in the attached figures are explained as follows:
[0037] 100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h, 100i, 100R, 100G1, 100G2, 100B: QPD unit
[0038] 110, 110a, 110b, 110c, 110d: Photodiodes
[0039] 120: Substrate
[0040] 130: Deep trench isolation structure
[0041] 132: Exterior wall
[0042] 134: Interior walls
[0043] 140: Grille
[0044] 150: Color Filter
[0045] 160: Optical components
[0046] 160A: First optical element
[0047] 160B: Second optical element
[0048] 162: Circular Lens
[0049] 1621: Outer contour
[0050] 1622: Inner contour
[0051] 164: Central Lens
[0052] 1641: Outer contour
[0053] 200A, 200B, 200C, 200D, 200E, 200F, 200G, 200H: Grouped QPD units
[0054] 300, 300A, 300B, 300C, 300D: Image Sensor
[0055] 310, 310A, 310B, 310C: QPD Units
[0056] 312: Optical Components
[0057] 314: Circular Lens
[0058] 316: Central lens
[0059] 318: Photodiode
[0060] 320: Optical components
[0061] 322: Spherical lens
[0062] C0, C1: Center
[0063] D1, D2: Dimensions
[0064] D3: Color Spacing Dimensions
[0065] E: Total Energy
[0066] E1, E2, E3, E3(R), E3(L), E4: Energy
[0067] H1, H2: Height
[0068] L1: External tangent
[0069] L2: Long axis
[0070] ML: Microlens
[0071] S1: Offset Detailed Implementation
[0072] The following describes several embodiments of this disclosure with reference to the accompanying drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit this disclosure. That is, these practical details are not essential in some embodiments of this disclosure. Furthermore, for the sake of simplicity, some conventional structures and elements will be illustrated in a simple schematic manner in the drawings, and the same reference numerals will be used to denote the same or similar elements in all drawings. And, where feasible, features of different embodiments can be applied interchangeably.
[0073] Furthermore, relative terms, such as "below" or "bottom" and "above" or "top," are used to describe the relationship between one element and another shown in the accompanying drawings. It is understandable that relative terms are used to describe different orientations of the device beyond those depicted in the drawings. For example, if a device in a drawing is flipped, an element originally described as being "below" another element will be oriented as being "above" another element. The illustrative term "below" can encompass both "below" and "above" orientations depending on the specific orientation of the drawing.
[0074] Reference Figure 1 and Figure 2 . Figure 1 This is a cross-sectional view of a portion of an image sensor according to some embodiments of the present disclosure. Figure 2This is a top view of a quadrature phase detection (QPD) unit of an image sensor according to some embodiments of the present disclosure. The image sensor 10 includes a plurality of QPD units 100 arranged in an array. Each QPD unit 100 includes four photodiodes 110 formed in a substrate 120, and the photodiodes 110 are defined and separated by a deep trench isolation structure 130. The photodiodes 110 in the QPD unit 100 are arranged in a two-column by two-row array. The deep trench isolation structure 130 includes an outer wall 132 surrounding the array of photodiodes 110 and an inner wall 134 for separating the photodiodes 110. Adjacent QPD units 100 share the outer wall 132 of the deep trench isolation structure 130.
[0075] Each QPD unit 100 includes a grille 140 disposed on the outer wall 132 of the deep trench isolation structure 130. The grille 140 defines a cavity, and each QPD unit 100 includes a corresponding color filter 150 disposed on a photodiode 110 and filling the cavity defined by the grille 140. In some embodiments, each color filter 150 overlaps four photodiodes 110, and each photodiode 110 is square.
[0076] One of the QPD units 100, such as Figure 2 The QPD unit 100a shown includes an optical element 160 disposed on a color filter 150. The optical element 160 includes an annular lens 162 and a central lens 164 surrounded by the annular lens 162. The central lens 164 overlaps on four photodiodes 110 of the QPD unit 100a, while multiple portions of the annular lens 162 overlap on the outer wall 132 of the deep trench isolation structure 130.
[0077] In some embodiments, the shape of the central lens 164 may be the same as or different from the shape of the annular lens 162. For example, the central lens 164 may be circular, and the annular lens 162 may be annular, as viewed from the top view. In some embodiments, the annular lens 162 and the central lens 164 are made of the same material, and the refractive indices of the annular lens 162 and the central lens 164 are between 1.5 and 2.5. In some embodiments, the annular lens 162 and the central lens 164 are manufactured using the same process, and the annular lens 162 is connected to the central lens 164.
[0078] Ideally, the incident light focused by optical element 160 should be split by deep trench isolation structure 130 and evenly distributed onto photodiode 110 as incident light spots of similar size. However, in most cases, the angle of incident light onto QPD cell 100 is not always normal, resulting in offset and asymmetrical incident light spots onto photodiode 110. Furthermore, QPD cell 100 is highly sensitive to alignment deviations of optical element 160 caused by photolithography misalignment. In some cases, QPD cells 100 at the edge of the wafer have larger incident light angles than those at the center, thus requiring less tolerance for alignment deviations of optical element 160.
[0079] Optical element 160 is used to compensate for the problem of light reception imbalance in QPD unit 100, especially the problem caused by the alignment misalignment of optical element 160 and / or the increased incident light angle. Optical element 160, which includes an annular lens 162 and a central lens 164, can provide more than one focal point on photodiode 110.
[0080] Reference Figure 3A as well as Figure 3B . Figure 3A as well as Figure 3B These are cross-sectional and top views of a QPD unit of an image sensor according to some embodiments of the present disclosure. The optical element 160 in the QPD unit 100b includes an annular lens 162 and a central lens 164. The height H1 of the annular lens 162 is less than the height H2 of the central lens 164. In some embodiments, the ratio of the height H1 of the annular lens 162 to the height H2 of the central lens 164 is between 45% and 65%. In some embodiments, the height H1 of the annular lens 162 is between 0.25 μm and 0.35 μm.
[0081] In some embodiments, the size D1 of the annular lens 162 is smaller than the size D2 of the central lens 164. In some embodiments, the ratio of the size D1 of the annular lens 162 to a color spacing dimension D3 is between 14% and 25%. The size D1 of the annular lens 162 and the size D2 of the central lens 164 are both measured in the same direction, and the size D1 of the annular lens 162 is measured on the bottom surface of the solid portion of the annular lens 162. The color spacing dimension D3 is the distance between the centers of two opposite portions of the grid 140. In some embodiments, the size D1 of the annular lens 162 is between 0.20 μm and 0.30 μm.
[0082] In some embodiments, such as in Figure 3A as well as Figure 3BIn the QPD unit 100b shown, the outer tangent L1 of the annular lens 162 of the optical element 160 of the QPD unit 100b is aligned with the major axis L2 of the outer wall 132 of the deep trench isolation structure 130, wherein the major axis L2 of the outer wall 132 passes through the center of the outer wall 132. In this embodiment, the optical element 160 is manufactured precisely according to the layout design, and no alignment error occurs during the manufacturing process of the optical element 160.
[0083] Reference Figure 4A as well as Figure 4B . Figure 4A as well as Figure 4B The figures shown are cross-sectional and top views of the QPD unit of an image sensor according to other embodiments of this disclosure. In some other embodiments, such as QPD unit 100c, undesirable and unavoidable alignment errors occur during the fabrication of optical element 160, causing the center C1 of optical element 160 to deviate from the center C0 of QPD unit 100c. In some embodiments, the offset S1 between the center C1 of optical element 160 and the center C0 of QPD unit 100c is equal to or less than 50 nm.
[0084] Reference Figure 5A as well as Figure 5B . Figure 5A This is a top view of an existing QPD cell with alignment error. Figure 5B This is a schematic diagram of the operation of an existing QPD cell with alignment error, wherein... Figure 5B For along Figure 5A It cuts through the diagonal. In Figure 5A In this configuration, a microlens ML is positioned on the photodiode 110, and due to alignment errors, the microlens ML is offset relative to the center of the photodiode 110. The photodiode 110a (PD Max), located directly below the focal point of the microlens ML, has the maximum light reception, while the photodiode 110b (PD Min) on its diagonal has the minimum light reception. The L / R balance is then calculated as the light reception of PD Max divided by the light reception of PD Min. The ratio of maximum to minimum light reception in the existing QPD unit further increases with increasing non-zero angle of incidence entering the QPD unit.
[0085] like Figure 5BAs shown, the total energy E collected by the microlens ML and focused onto photodiodes 110a (PD Max) and 110b (PD Min) is E1 + E2 + E3 + E4. E1 and E2 represent the light received from the central region closer to the microlens ML, while E3 and E4 represent the light received from the edge region closer to the microlens ML. E1 and E2, and E3 and E4 are symmetrical. Due to alignment errors, energy E3 is concentrated on the inner wall 134 of the deep trench isolation structure 130, rather than tending to be concentrated on photodiode 110b. Energy E4 is almost completely blocked by the grid and can be considered close to zero. Energy E3 is split by the inner wall 134 of the deep trench isolation structure 130, resulting in a portion of energy E3(L) being allocated to photodiode 110a (PD Max) and a portion of energy E3(R) being allocated to photodiode 110b (PD Min). The L / R balance of this existing QPD unit is (E1+E2+E3(L)) / E3(R).
[0086] Reference Figure 5C as well as Figure 5D . Figure 5C This is a top view of a QPD cell with alignment error according to an embodiment of the present disclosure. Figure 5D This is a schematic diagram of the operation of a QPD unit according to an embodiment of the present disclosure, wherein... Figure 5D For along Figure 5C It cuts through the diagonal. For example... Figure 5C As shown, the optical element 160 of the QPD unit 100c includes an annular lens 162 and a central lens 164, and the optical element 160 can provide more than one focal point on the photodiode 110. For example, the optical element 160 is disposed on the photodiode 110, and the optical element 160 is offset relative to the center of the photodiode 110 due to alignment errors. The photodiode 110c (PD Max) is directly located below the focal point of the central lens 164, and therefore has the maximum light reception, while its diagonal photodiode 110d (PD Min) has the minimum light reception.
[0087] like Figure 5DAs shown, the total energy E focused by optical element 160 onto photodiode 110c (PD Max) and photodiode 110d (PD Min) is E1 + E2 + E3 + E4, where E1 and E2 correspond to the light received by central lens 164, and E3 and E4 correspond to the light received by annular lens 162. E1 and E2, and E3 and E4 are symmetrical. Due to alignment error, energy E4 is almost completely deviated from QPD unit 100c. Energy E3, however, is focused by central lens 164 and falls almost entirely on photodiode 110d. The L / R balance of QPD unit 100c is (E1 + E2) / E3, where E3 is equivalent to... Figure 5B The sum of E3(L) and E3(R) in the QPD unit 100c is used to improve the L / R balance.
[0088] Next, please refer to Table 1, which presents simulation results for several examples of existing QPD units using microlenses as optical elements under different alignment errors, and several embodiments of the QPD unit of this disclosure using annular lenses and central lenses as optical elements under different alignment errors. According to the simulation results, as the alignment error increases, the L / R balance deteriorates. However, the L / R balance of the QPD units in the various embodiments of this disclosure is still lower than that of the existing QPD units. With larger alignment errors, such as 50 nm, the improvement rate of the L / R balance by the QPD units in the various embodiments of this disclosure is more significant than with smaller alignment errors, such as 20 nm. According to the simulation results, within the alignment error range of 50 nm, the QPD units in the various embodiments of this disclosure have a significant compensation effect on the light-gathering balance.
[0089]
[0090] Table 1
[0091] Next, please refer to Table 2, which shows simulation results at different wafer locations for several examples of existing QPD cells using microlenses as optical elements and several embodiments of the QPD cells of this disclosure using annular lenses and central lenses as optical elements. The angle of incidence varies at different wafer locations. For example, the angle of incidence of a QPD cell at the wafer edge is greater than that at the wafer center, resulting in a worse quantum efficiency (QE) at the wafer edge compared to the wafer center. The quantum efficiencies of the QPD cells in the embodiments of this disclosure are superior to those of the existing examples of QPD cells. Furthermore, the improvement in quantum efficiency at the wafer edge is more significant than the improvement at the wafer center.
[0092]
[0093] Table 2
[0094] Reference Figures 6A to 6F , Figures 6A to 6F This is a top view of a QPD unit according to different embodiments of the present disclosure. The shapes of the central lens 164 and the annular lens 162 can have a variety of different variations. For example, such as Figure 6A As shown in QPD unit 100d, the outer contour 1621 of the annular lens 162 has the same shape as the inner contour 1622 of the annular lens 162, and the outer contour 1621 of the annular lens 162 is polygonal, such as an octagon. The outer contour 1641 of the central lens 164 has the same shape as the inner contour 1622 of the annular lens 162, and is also an octagon.
[0095] In some embodiments, such as Figure 6B As shown in QPD unit 100e, the outer contour 1621 of the annular lens 162 has the same shape as the inner contour 1622 of the annular lens 162, and both the outer contour 1621 and the inner contour 1622 of the annular lens 162 are squares with rounded corners. The outer contour 1641 of the central lens 164 has the same shape as the inner contour 1622 of the annular lens 162, and is also a square with rounded corners.
[0096] In some embodiments, such as Figure 6C As shown in QPD unit 100f, the outer contour 1621 of the annular lens 162 has the same shape as the inner contour 1622 of the annular lens 162, and both the outer contour 1621 and the inner contour 1622 of the annular lens 162 are square. The outer contour 1641 of the central lens 164 has the same shape as the inner contour 1622 of the annular lens 162, and is also square.
[0097] In some embodiments, such as Figure 6D As shown in the QPD unit 100g, the shape of the outer contour 1621 of the annular lens 162 is different from the shape of the inner contour 1622 of the annular lens 162. For example, the outer contour 1621 of the annular lens 162 is octagonal, while the inner contour 1622 of the annular lens 162 is circular. The outer contour 1641 of the central lens 164 is the same as the inner contour 1622 of the annular lens 162, which is also circular.
[0098] In some embodiments, such as Figure 6EAs shown in the QPD unit 100h, the shape of the outer contour 1621 of the annular lens 162 is different from the shape of the inner contour 1622 of the annular lens 162. For example, the outer contour 1621 of the annular lens 162 is a square with rounded corners, while the inner contour 1622 of the annular lens 162 is circular. The outer contour 1641 of the central lens 164 is the same as the inner contour 1622 of the annular lens 162, which is also circular.
[0099] In some embodiments, such as Figure 6F As shown in the QPD unit 100i, the shape of the outer contour 1621 of the annular lens 162 is different from the shape of the inner contour 1622 of the annular lens 162. For example, the outer contour 1621 of the annular lens 162 is square, while the inner contour 1622 of the annular lens 162 is circular. The outer contour 1641 of the central lens 164 is the same as the inner contour 1622 of the annular lens 162, which is also circular.
[0100] Reference Figures 7A to 7I , Figures 7A to 7I This is a top view of a group of QPD units according to different embodiments of the present disclosure. In some embodiments, each group of QPD units 200A-200H includes four QPD units such as QPD units 100R, 100G1, 100G2, and 100B, arranged in a Bayer configuration. Each QPD unit 100R, 100G1, 100G2, and 100B includes four QPD units 100 arranged in an array, a deep trench isolation structure 130 having an outer wall 132 surrounding a photodiode 110 and an inner wall 134 separating the photodiodes 110, a corresponding color filter 150 disposed on the array of photodiodes 110, and an optical element 160 disposed on the color filter 150. Depending on the different filtering bands of the QPD units 100R, 100G1, 100G2, and 100B, the optical element 160 disposed on the color filter 150 can also be further designed to improve optical performance.
[0101] In some embodiments, such as Figure 7A In the group of QPD units 200A shown, the optical elements 160 located on the different QPD units 100R, 100G1, 100G2, and 100B are substantially identical. Each optical element 160 includes an annular lens 162 and a central lens 164 surrounded by the annular lens 162, wherein multiple portions of the annular lens 162 overlap on the outer wall 132 of the deep trench isolation structure 130.
[0102] In some embodiments, such as Figure 7BIn the group of QPD units 200B shown, the shape of the optical element 160 located above the QPD unit 100R is different from the shape of the optical element 160 located on the QPD unit 100G1, the shape of the optical element 160 located on the QPD unit 100G1 is the same as the shape of the optical element 160 located on the QPD unit 100G2, and the shape of the optical element 160 located above the QPD unit 100B can be the same as or different from the shape of the optical element 160 located above the QPD unit 100R.
[0103] In some embodiments, such as Figure 7C In the group of QPD units 200C shown, the optical elements 160 located on different QPD units 100R, 100G1, 100G2, and 100B have substantially the same shape, but the fill factor between the annular lens 162 and the central lens 164 can be varied. For example, the fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100B is greater than the fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100G1. The fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100G1 is the same as the fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100G2. The fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100R is less than the fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100G1. In other words, in some embodiments, the fill factor relationship of the annular lens 162 of the optical element 160 is B>G>R.
[0104] In some embodiments, such as Figure 7D In the group of QPD units 200D shown, the optical elements 160 located in different QPD units 100R, 100G1, 100G2, and 100B have substantially the same shape, but the fill factor between the annular lens 162 and the central lens 164 can be varied. For example, the fill factor of the annular lens 162 of the optical element 160 located in QPD unit 100R is greater than the fill factor of the annular lens 162 of the optical element 160 located in QPD unit 100G1. The fill factor of the annular lens 162 of the optical element 160 located in QPD unit 100G1 is the same as the fill factor of the annular lens 162 of the optical element 160 located in QPD unit 100G2. The fill factor of the annular lens 162 of the optical element 160 located in QPD unit 100B is smaller than the fill factor of the annular lens 162 of the optical element 160 located in QPD unit 100G1. In other words, in some embodiments, the fill factor relationship of the annular lens 162 of the optical element 160 is R>G>B.
[0105] In some embodiments, such as Figure 7E In the group of QPD units 200E shown, the optical elements 160 located on different QPD units 100R, 100G1, 100G2, and 100B have different shapes. For example, the optical element 160 located on QPD unit 100G1 or QPD unit 100G2 is a single spherical lens, while the optical elements 160 located on QPD units 100R and QPD unit 100B have an annular lens 162 and a central lens 164. The fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100B is greater than the fill factor of the annular lens 162 of the optical element 160 located on QPD unit 100R. In other words, in some embodiments, the fill factor relationship of the annular lens 162 of the optical element 160 is B>R>G=0.
[0106] In some embodiments, such as Figure 7F In the group of QPD units 200F shown, the optical elements 160 located on different QPD units 100R, 100G1, 100G2, and 100B respectively include annular lenses 162 and central lenses 164, and the shapes of these optical elements 160 may be the same or different. In some embodiments, the annular lenses 162 of QPD units 100R, 100G1, 100G2, and 100B may be further connected together.
[0107] In some embodiments, such as Figure 7GIn the grouped QPD units 200G shown, the optical elements 160 located on QPD units 100R and 100B are different from those located on QPD units 100G1 and 100G2. The optical elements 160 on QPD units 100G1 and 100G2 each include an annular lens 162 and a central lens 164, with the central lens 164 overlapping four photodiodes 110. QPD units 100R and 100B each include a first optical element 160A and a second optical element 160B. The first optical element 160A includes an annular lens 162 and a central lens 164, with the central lens 164 overlapping two adjacent photodiodes 110, and both the annular lens 162 and the central lens 164 having an elliptical shape. The second optical element 160B includes an annular lens 162 and a central lens 164, the central lens 164 being superimposed on two other adjacent photodiodes 110, and the annular lens 162 and the central lens 164 having an elliptical shape. In other words, optical element 160 can correspond to a 2x2 array of photodiodes 110, while the first optical element 160A and the second optical element 160B correspond to a 2x1 array of photodiodes 110.
[0108] In some embodiments, such as Figure 7H In the grouped QPD units 200H shown, the optical elements 160 located on QPD units 100R and 100B each include an annular lens 162 and a central lens 164, with the central lens 164 overlapping four photodiodes 110. QPD units 100G1 and 100G2 each include a first optical element 160A and a second optical element 160B. The first optical element 160A includes an annular lens 162 and a central lens 164, with the central lens 164 overlapping two adjacent photodiodes 110, and both the annular lens 162 and the central lens 164 having an elliptical shape. The second optical element 160B includes an annular lens 162 and a central lens 164, with the central lens 164 overlapping two other adjacent photodiodes 110, and both the annular lens 162 and the central lens 164 having an elliptical shape.
[0109] In some embodiments, such as Figure 7IIn the grouped QPD units 200I shown, the optical elements 160 located on QPD units 100R, 100G1, 100G2, and 100B each include a first optical element 160A and a second optical element 160B. The first optical element 160A includes an annular lens 162 and a central lens 164. The central lens 164 is superimposed on two adjacent photodiodes 110, and both the annular lens 162 and the central lens 164 have elliptical shapes. The second optical element 160B includes an annular lens 162 and a central lens 164. The central lens 164 is superimposed on two other adjacent photodiodes 110, and both the annular lens 162 and the central lens 164 have elliptical shapes.
[0110] Reference Figures 8A to 8D , Figures 8A to 8D This is a top view of an image sensor according to different embodiments of the present disclosure. In some embodiments, such as... Figure 8A In the image sensor 300A shown, one QPD unit, such as QPD unit 310A, includes an optical element 312, which includes a ring lens 314 and a central lens 316, with the central lens 316 superimposed on four photodiodes 318. Another QPD unit, such as QPD unit 310B, includes an optical element 320, which includes four spherical lenses 322, each disposed on one of the four photodiodes 318.
[0111] In some embodiments, such as Figure 8B In the image sensor 300B shown, one QPD unit, such as QPD unit 310A, includes an optical element 312, which includes a ring lens 314 and a central lens 316, with the central lens 316 superimposed on four photodiodes 318. Another QPD unit, such as QPD unit 310C, includes an optical element 320, which includes four optical elements 312. Each optical element 312 includes a ring lens 314 and a central lens 316, and the central lens 316 of each optical element 312 in QPD unit 310C is disposed on a photodiode 318.
[0112] In some embodiments, such as Figure 8C In the image sensor 300C shown, QPD units 310A and QPD units 310B can be arranged alternately in rows and columns. In some other embodiments, such as Figure 8D In the image sensor 300D shown, QPD units 310A and QPD units 310C can be arranged alternately in rows and columns.
[0113] Although this disclosure has been presented above with reference to embodiments, it is not intended to limit this disclosure. Any person skilled in the art can make various changes and modifications without departing from the concept and scope of this disclosure. Therefore, the scope of protection of this disclosure shall be determined by the claims.
Claims
1. An image sensor, characterized in that, Include: A first four-quadrant phase sensing unit, comprising: Four photodiodes are arranged in an array of two columns by two rows; A deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiode and the inner wall being configured to separate the photodiode; A grid is installed on the deep trench isolation structure; A color filter is disposed on the photodiode and fills the grid; as well as An optical element is disposed on the color filter, the optical element comprising an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.
2. The image sensor of claim 1, wherein the annular lens and the central lens are made of the same material, the refractive index of the annular lens and the central lens is between 1.5 and 2.5, and the height of the annular lens is less than the height of the central lens, and the size of the annular lens is less than the size of the central lens.
3. The image sensor of claim 1, wherein the ratio between the height of the annular lens and the height of the central lens is between 45% and 65%, and the ratio between the size of the annular lens and a color spacing dimension is between 14% and 25%, wherein the color spacing dimension is the distance between the centers of two opposite portions of the grid.
4. The image sensor of claim 1, wherein an outer tangent of the annular lens is aligned with a long axis of the outer wall of the deep trench isolation structure.
5. The image sensor of claim 1, wherein an outer tangent of the annular lens is offset relative to a major axis of the outer wall of the deep trench isolation structure, and the offset between the outer tangent of the annular lens and the major axis of the outer wall of the deep trench isolation structure is equal to or less than 50 nm.
6. The image sensor of claim 1, wherein the outer contour of the annular lens has the same shape as or different from the inner contour of the annular lens, and the central lens overlaps the photodiode.
7. The image sensor of claim 1, wherein the central lens overlaps two of the photodiodes, the image sensor further comprising another optical element disposed on the color filter and overlapped on two other of the photodiodes, the other optical element comprising an annular lens and a central lens surrounded by the annular lens, wherein a plurality of portions of the annular lens of the other optical element overlap the outer wall of the deep trench isolation structure.
8. The image sensor of claim 1, further comprising: A second fourth quadrant phase sensing unit, comprising: Four photodiodes are arranged in an array of two columns by two rows; A deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiode and the inner wall being configured to separate the photodiode; A color filter is disposed on the photodiode, wherein the filtering band of the color filter in the second four-quadrant phase sensing unit is different from the filtering band of the color filter in the first four-quadrant phase sensing unit; and An optical element is disposed on the color filter. The optical element of the second four-quadrant phase sensing unit includes an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.
9. The image sensor of claim 8, wherein the annular lens of the first four-quadrant phase sensing unit is connected in parallel with the annular lens of the second four-quadrant phase sensing unit.
10. The image sensor of claim 8, wherein the shape of the optical element of the first four-quadrant phase sensing unit is different from the shape of the optical element of the second four-quadrant phase sensing unit, or the fill factor of the annular lens of the first four-quadrant phase sensing unit is different from the fill factor of the annular lens of the second four-quadrant phase sensing unit.
11. The image sensor of claim 1, further comprising: A second fourth quadrant phase sensing unit, comprising: Four photodiodes are arranged in an array of two columns by two rows; A deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiode and the inner wall being configured to separate the photodiode; A color filter is disposed on the photodiode, wherein the filtering band of the color filter in the second four-quadrant phase sensing unit is different from the filtering band of the color filter in the first four-quadrant phase sensing unit; and An optical element is disposed on the color filter, wherein the optical element of the second four-quadrant phase sensing unit includes four spherical lenses, which are respectively disposed on the photodiode.
12. The image sensor of claim 1, further comprising: A second fourth quadrant phase sensing unit, comprising: Four photodiodes are arranged in an array of two columns by two rows; A deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiode and the inner wall being configured to separate the photodiode; A color filter is disposed on the photodiode, wherein the filtering band of the color filter in the second four-quadrant phase sensing unit is different from the filtering band of the color filter in the first four-quadrant phase sensing unit; and An optical element is disposed on the color filter, wherein the optical element of the second four-quadrant phase sensing unit includes a single spherical lens disposed on the photodiode.
13. The image sensor of claim 1, further comprising: A second fourth quadrant phase sensing unit, comprising: Four photodiodes are arranged in an array of two columns by two rows; A deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiode and the inner wall being configured to separate the photodiode; A color filter is disposed on the photodiode, wherein the filtering band of the color filter of the second four-quadrant phase sensing unit is different from the filtering band of the color filter of the first four-quadrant phase sensing unit. A first optical element, disposed on the color filter and located adjacent to each other in the photodiode, the first optical element comprising an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure; and A second optical element, disposed on the color filter and located on the other two of the photodiodes, the second optical element comprising an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.
14. The image sensor of claim 1, further comprising: A second fourth quadrant phase sensing unit, comprising: Four photodiodes are arranged in an array of two columns by two rows; A deep trench isolation structure includes an outer wall and an inner wall, the outer wall surrounding the photodiode and the inner wall being configured to separate the photodiode; A color filter is disposed on the photodiode, wherein the filtering band of the color filter in the second four-quadrant phase sensing unit is different from the filtering band of the color filter in the first four-quadrant phase sensing unit; and Four optical elements are disposed on the color filter and respectively located on the photodiode. Each optical element includes an annular lens and a central lens surrounded by the annular lens, wherein multiple portions of the annular lens overlap the outer wall of the deep trench isolation structure.