Image sensor

Abstract

An image sensor includes a photoelectric conversion layer, a color filter layer disposed on the photoelectric conversion layer, a buffer layer disposed on the color filter layer, a metasurface layer, and an anti-reflection layer covering the metasurface layer. The metamaterial layer includes a liner layer disposed on the buffer layer and a plurality of top microstructures on the liner layer, the top microstructures protruding from the liner layer in a direction away from the photoelectric conversion layer. The anti-reflection layer comprises a first part and a second part, the first part is located on the top surface of a first top microstructure in the top microstructures, the second part is located on the side wall of the first top microstructure, and the height of the first part is larger than the width of the second part. The anti-reflection layer is non-conformally overlying the metasurface layer to further reduce the reflectivity of the microstructure and improve the optical performance of the image sensor.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an image sensor. BACKGROUND

[0002] With the development of semiconductor technology, there is an increasing demand for smaller size complementary metal oxide semiconductor (CMOS) image sensors (also referred to as CIS). In a CIS, the arrangement and size of elements in an optical device affect the focal length of light, which in turn affects the thickness of the elements. SUMMARY

[0003] One embodiment of the present disclosure provides an image sensor, including a photoelectric conversion layer, a color filter layer disposed on the photoelectric conversion layer, a buffer layer disposed on the color filter layer, a superstrate layer, and an anti-reflective layer covering the superstrate layer. The superstrate layer includes a base layer disposed on the buffer layer and a plurality of top microstructures on the base layer, the top microstructures protruding from the base layer in a direction away from the photoelectric conversion layer. The anti-reflective layer includes a first portion on a top surface of a first top microstructure of the top microstructures and a second portion on a sidewall of the first top microstructure, and a height of the first portion is greater than a width of the second portion.

[0004] In some embodiments, the height is measured at a center of the top surface of the first top microstructure in the direction away from the photoelectric conversion layer, and the width is measured at a midpoint of the sidewall of the first top microstructure in a direction perpendicular to the direction away from the photoelectric conversion layer.

[0005] In some embodiments, the anti-reflective layer includes a third portion on a top surface of the base layer, and a height of the third portion is greater than the width of the second portion.

[0006] In some embodiments, a ratio of the height of the first portion to the width of the second portion is greater than or equal to 1.2, and a ratio of the height of the third portion to the width of the second portion is greater than or equal to 1.3.

[0007] In some embodiments, a ratio of the height of the first portion to the width of the second portion is greater than or equal to 1.5, and a ratio of the height of the third portion to the width of the second portion is greater than or equal to 1.7.

[0008] In some embodiments, the first portion has a rounded corner, and a radius of curvature of the rounded corner is less than the height of the first portion.

[0009] In some embodiments, the first portion has a rounded corner, and a radius of curvature of the rounded corner is less than the height of the first portion.

[0010] In some embodiments, the anti-reflective layer partially connects on adjacent top microstructures, and air cavities surrounded by the anti-reflective layer are disposed between the adjacent top microstructures.

[0011] In some embodiments, the image sensor further comprises a protective layer disposed on the anti-reflective layer, the anti-reflective layer has a refractive index greater than a refractive index of the protective layer, and the protective layer has a refractive index greater than 1.

[0012] In some embodiments, the image sensor further comprises a top refractive index matching layer disposed between the anti-reflective layer and the top surface of the first top microstructure, the superstrate has a refractive index greater than a refractive index of the top refractive index matching layer, and the top refractive index matching layer has a refractive index greater than or equal to a refractive index of the anti-reflective layer.

[0013] In some embodiments, the image sensor further comprises a bottom refractive index matching layer disposed between the buffer layer and the bottom surface of the liner layer, the superstrate has a refractive index greater than a refractive index of the bottom refractive index matching layer, and the bottom refractive index matching layer has a refractive index greater than or equal to a refractive index of the buffer layer.

[0014] In some embodiments, the bottom refractive index matching layer has a thickness less than or equal to a thickness of the top refractive index matching layer.

[0015] In some embodiments, the image sensor further comprises a top refractive index matching layer disposed between the anti-reflective layer and the top surface of the first top microstructure, wherein the anti-reflective layer directly contacts a top surface of a second top microstructure of the top microstructures.

[0016] In some embodiments, the first top microstructure and the second top microstructure are located in a same color filter region of the color filter layer.

[0017] In some embodiments, the first top microstructure and the second top microstructure are located in different color filter regions of the color filter layer, respectively.

[0018] In some embodiments, the anti-reflective layer comprises a fourth portion disposed on the top surface of the second top microstructure, and a sum of a thickness of the top refractive index matching layer and a height of the first portion is greater than a height of the fourth portion.

[0019] In some embodiments, the anti-reflective layer comprises a fourth portion disposed on a top surface of a second top microstructure of the top microstructures and a fifth portion disposed on a sidewall of the second top microstructure, a height of the fourth portion is greater than a width of the fifth portion, and a first ratio of a height of the first portion to a width of the second portion is greater than a second ratio of the height of the fourth portion to the width of the fifth portion.

[0020] In some embodiments, the superstrate has a refractive index greater than a refractive index of the anti-reflective layer, and the anti-reflective layer has a refractive index greater than 1.

[0021] In some embodiments, the super-layer includes a plurality of bottom microstructures protruding from the liner layer in a direction toward the photoelectric conversion layer, and the bottom microstructures are misaligned with the top microstructures.

[0022] In some embodiments, the image sensor further includes an inner super-layer disposed on the buffer layer, an inner top refractive index matching layer disposed between the buffer layer and a top surface of the top microstructure in the inner super-layer, and an inner bottom refractive index matching layer disposed between the buffer layer and a bottom surface of the liner layer in the inner super-layer.

[0023] An image sensor of some embodiments of the present disclosure includes a super-layer on a photoelectric conversion layer and having a plurality of microstructures, and an anti-reflective layer on the super-layer to reduce reflectivity of the microstructures. The anti-reflective layer is non-conformally coated on the super-layer to further reduce reflectivity of the microstructures and improve optical performance of the image sensor. BRIEF DESCRIPTION OF DRAWINGS

[0024] To make the purposes, features, advantages and embodiments of the present disclosure more obvious and easy to understand, the detailed description of the accompanying drawings is as follows:

[0025] Figure 1 A top view schematic diagram of some embodiments of the image sensor according to the present disclosure.

[0026] Figure 2 A cross-sectional view of some embodiments of the image sensor according to the present disclosure.

[0027] Figure 3 A zoomed-in view of region A in the image sensor of Figure 2

[0028] Figures 4A to 4C Schematic diagrams of different steps of forming an anti-reflective layer on a super-layer according to some embodiments of the present disclosure, respectively.

[0029] Figures 5 to 11 Cross-sectional zoomed-in views of different embodiments of the image sensor according to the present disclosure, respectively.

[0030] Figures 12 to 15 Cross-sectional views of different embodiments of the image sensor according to the present disclosure, respectively.

[0031] In which, the reference signs are explained as follows:

[0032] 100: image sensor

[0033] 110: photoelectric conversion layer

[0034] 112: photodiode

[0035] 114: deep trench isolation structure​

[0036] 120: color filter layer

[0037] 122: color filter block

[0038] 122a: color filter block / first color filter block

[0039] 122b: second color filter block

[0040] 124: grid structure

[0041] 130: buffer layer

[0042] 140: superstrate

[0043] 142: liner layer

[0044] 142t: top surface

[0045] 142b: bottom surface

[0046] 144: top microstructure

[0047] 144t: top surface

[0048] 144s: sidewall

[0049] 145: bottom microstructure

[0050] 145b: bottom surface

[0051] 146: first top microstructure

[0052] 146t: top surface

[0053] 146s: sidewall

[0054] 148: second top microstructure

[0055] 148t: top surface

[0056] 148s: sidewall

[0057] 150: anti-reflective layer

[0058] 150': low refractive index material

[0059] 151: first portion

[0060] 151c: rounded corner

[0061] 151h: rounded head

[0062] 152: second portion

[0063] 153: third portion

[0064] 154: fourth portion

[0065] 155: fifth portion

[0066] 160: hard mask pattern

[0067] 170: protective layer

[0068] 180: top index matching layer

[0069] 190: bottom index matching layer

[0070] 200: inner superstrate layer

[0071] 202: liner layer

[0072] 202b: bottom surface

[0073] 204: inner top microstructure

[0074] 204t: top surface

[0075] 206: inner bottom microstructure

[0076] 210: inner top index matching layer

[0077] 220: inner bottom index matching layer

[0078] A: area

[0079] AG: air cavity

[0080] D1, D2, D3: direction

[0081] H1, H2, H3: height

[0082] R: radius of curvature

[0083] T1, T2: thickness

[0084] W1, W2, W3: width DETAILED DESCRIPTION

[0085] A number of implementations of the disclosure will now be described with reference to the following drawings. Details of the implementation can be illustrated in the following description and drawings. It will be appreciated that the following examples are not limiting and that many variations and modifications of the implementations described herein are possible that remain within the scope of the present disclosure. The implementations described herein are directed to overcoming one or more of the difficulties set forth above. Moreover, for the sake of brevity, certain implementations will be described in detail without referencing every aspect of the implementations. Those skilled in the art will understand that the implementations described herein can include more than what is described in this detailed description. Further, to assist with clarity and understanding, certain terms that can be used throughout the description are defined below.

[0086] In addition, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

[0087] The image sensor of the present disclosure can shorten the focal length of light by adjusting the phase difference. In some embodiments of the present disclosure, the phase difference is adjusted by a meta layer having a microstructure with a high refractive index. The microstructure in the image sensor of the present disclosure is further covered with an anti-reflection layer, thereby reducing the reflectivity of the microstructure. More specifically, the anti-reflection layer in the image sensor of the present disclosure is non-conformally covered on the microstructure of the meta layer to further reduce the reflectivity and improve the optical performance.

[0088] Reference Figure 1 With Figure 2 , Figure 1 is a top view schematic diagram of some embodiments of the image sensor according to the present disclosure, Figure 2 is a cross-sectional view of some embodiments of the image sensor according to the present disclosure. The image sensor 100 includes a photoelectric conversion layer 110, a color filter layer 120 disposed on the photoelectric conversion layer 110, a buffer layer 130 disposed on the color filter layer 120, a meta layer 140 disposed on the buffer layer 130, and an anti-reflection layer 150 covering the meta layer 140.

[0089] The photoelectric conversion layer 110 includes a plurality of photodiodes 112 and a deep trench isolation structure 114. The deep trench isolation structure 114 is disposed to separate the photodiodes 112. The color filter layer 120 includes a plurality of color filter blocks 122 surrounded by a grid structure 124. The color filter blocks 122 are respectively disposed on the corresponding photodiodes 112. The buffer layer 130 is disposed between the color filter layer 120 and the meta layer 140.

[0090] The meta layer 140 includes a base layer 142 disposed on the buffer layer 130 and a plurality of top microstructures 144. The top microstructures 144 are protruded from the base layer 142 in a direction D1 away from the photoelectric conversion layer 110. The base layer 142 and the top microstructures 144 are made of the same material, and the base layer 142 and the top microstructures 144 are integrally formed. The base layer 142 continuously covers the buffer layer 130 and has a uniform thickness.

[0091] In some embodiments, the size of the top microstructures 144, the spacing between the top microstructures 144, and / or the distribution density of the top microstructures 144 on the individual color filter patches 122 can be varied according to different optical design requirements. The anti-reflective layer 150 is non-conformally coated on the top surfaces of the top microstructures 144 of the superstrate 140. In some embodiments, the refractive index of the superstrate 140 is greater than the refractive index of the anti-reflective layer 150, and the refractive index of the anti-reflective layer 150 is greater than 1. In some embodiments, the material of the anti-reflective layer 150 includes inorganic oxide, resin, polyimide, acrylate, polyvinyl alcohol, or photoresist.

[0092] Reference is made next to Figure 3 , which is a zoomed-in view of region A in the image sensor 100 of Figure 2 , where region A illustrates a first top microstructure in the top microstructures of the image sensor of some embodiments of the present disclosure. For example, the anti-reflective layer 150 includes a first portion 151 on the top surface 146t of the first top microstructure 146 and a second portion 152 on the sidewall 146s of the first top microstructure 146. The height H1 of the first portion 151 is greater than the width W1 of the second portion 152. The height H1 is measured from the center of the top surface 146t of the first top microstructure 146 in the direction D1 away from the photoelectric conversion layer 110 (see Figure 2 ), and the width W1 is measured from the midpoint of the sidewall 146s of the first top microstructure 146 in the direction D2 perpendicular to the direction D1, where the direction D1 is the direction away from the photoelectric conversion layer 110. In some embodiments, the ratio between the height H1 of the first portion 151 and the width W1 of the second portion 152 is greater than 1.2. In some embodiments, the ratio between the height H1 of the first portion 151 and the width W1 of the second portion 152 is greater than 1.5 to provide better performance.

[0093] The anti-reflective layer 150 further includes a third portion 153 on the top surface 142t of the liner layer 142. The height H2 of the third portion 153 is also greater than the width W1 of the second portion 152. In some embodiments, the ratio between the height H2 of the third portion 153 and the width W1 of the second portion 152 is greater than 1.3. In some embodiments, the ratio between the height H2 of the third portion 153 and the width W1 of the second portion 152 is greater than 1.7 to provide better performance. The height H1 of the first portion 151 can be greater than, equal to, or less than the height H2 of the third portion 153.

[0094] Reference is made to Figures 4A to 4C , which are schematic diagrams of different steps of forming an anti-reflective layer on a superstrate according to some embodiments of the present disclosure, respectively. As shown in Figure 4AAs shown, the metamorphic layer 140 is formed on the buffer layer 130 , wherein the metamorphic layer 140 includes a liner layer 142 on the buffer layer 130 and a top microstructure 144 on the liner layer 142 .

[0095] like Figure 4B As shown, a low-refractive-index material 150' is deposited on the metalayer 140. The refractive index of the low-refractive-index material 150' is less than that of the metalayer 140 and is greater than 1. In some embodiments, the low-refractive-index material 150' fills the gaps between the top microstructures 144 and provides a flat top surface. Examples of the material of the low-refractive-index material 150' include inorganic oxides, resins, polyimides, acrylates, polyvinyl alcohol, or photoresists.

[0096] Next, a hard mask pattern 160 is formed on the low-refractive-index material 150'. The hard mask pattern 160 is formed on the corresponding top microstructure 144. The projection of the hard mask pattern 160 on the buffer layer 130 covers the projection of the top microstructure 144 on the buffer layer 130. More specifically, the projection of the hard mask pattern 160 is slightly larger than the projection of the corresponding top microstructure 144.

[0097] After the hard mask pattern 160 is formed on the top microstructure 144, the low-refractive-index material 150' is etched using the hard mask pattern 160 as a mask. The portion of the low-refractive-index material 150' covered by the hard mask pattern 160 is protected by the hard mask pattern 160 during the etching process, while the portion of the low-refractive-index material 150' not covered by the hard mask pattern 160 is removed during the etching process. In some embodiments, the hard mask pattern 160 may be removed after the etching process is complete. In other embodiments, the hard mask pattern 160 may be consumed during the etching process.

[0098] In this way, if Figure 4C As shown, the remaining low-refractive-index material serves as an anti-reflection layer 150 covering the metalayer 140. The anti-reflection layer 150 covers the liner layer 142 and the top microstructure 144 of the metalayer 140. The thickness of the anti-reflection layer 150 on the liner layer 142 and the top surface of the top microstructure 144 is greater than the thickness of the anti-reflection layer 150 on the sidewalls of the top microstructure 144.

[0099] Reference Figures 5 to 8 , which are enlarged cross-sectional views of different embodiments of the image sensor disclosed herein. In some embodiments, the shape of the anti-reflection layer 150 on the top microstructure 144 can be adjusted according to the selected etching process. For example, Figure 5As shown, the anti-reflective layer 150 includes a first portion 151 on the top surface 144t of the top microstructure 144 and a second portion 152 on the sidewall 144s of the top microstructure 144. The height H1 of the first portion 151 is greater than the width W1 of the second portion 152. The first portion 151 has a rounded corner 151c with a radius of curvature R that is less than the height H1 of the first portion 151. The top surface of the first portion 151 is arched.

[0100] Alternatively, as shown in FIG. 1C, the anti-reflective layer 150 includes a first portion 151 on the top surface 144t of the top microstructure 144 and a second portion 152 on the sidewall 144s of the top microstructure 144. The height H1 of the first portion 151 is greater than the width W1 of the second portion 152. The first portion 151 has a rounded head 151h that is laterally protruding from the second portion 152. In other words, the width W2 of the first portion 151 as measured from the sidewall 144s of the top microstructure 144 is greater than the width W1 of the second portion 152 as measured from the sidewall 144s of the top microstructure 144. The top surface of the first portion 151 is arched. Figure 6

[0101] Alternatively, as shown in FIG. 1C, the anti-reflective layer 150 includes a first portion 151 on the top surface 144t of the top microstructure 144 and a second portion 152 on the sidewall 144s of the top microstructure 144. The height H1 of the first portion 151 is greater than the width W1 of the second portion 152. The first portion 151 has a rounded head 151h that is laterally protruding from the second portion 152. In other words, the width W2 of the first portion 151 as measured from the sidewall 144s of the top microstructure 144 is greater than the width W1 of the second portion 152 as measured from the sidewall 144s of the top microstructure 144. The top surface of the first portion 151 is arched. Figure 7

[0102] The anti-reflective layer 150 includes a first portion 151 on the top surface 146t of the first top microstructure 146 and a second portion 152 on the sidewall 146s of the first top microstructure 146. The height H1 of the first portion 151 is greater than the width W1 of the second portion 152. The anti-reflective layer 150 includes a fourth portion 154 on the top surface 148t of the second top microstructure 148 and a fifth portion 155 on the sidewall 148s of the second top microstructure 148. The height H3 of the fourth portion 154 is greater than the width W3 of the fifth portion 155.

[0103] ​​In some embodiments, a first ratio between the height H1 of the first portion 151 and the width W1 of the second portion 152 may be the same as a second ratio between the height H3 of the fourth portion 154 and the width W3 of the fifth portion 155 .

[0104] In other embodiments, a first ratio between the height H1 of the first portion 151 and the width W1 of the second portion 152 may be greater than a second ratio between the height H3 of the fourth portion 154 and the width W3 of the fifth portion 155. In some embodiments, the anti-reflective layer 150 may have more than two aspect ratios (height / width) at different top microstructures 144.

[0105] Or, as Figure 8 As shown, the anti-reflection layer 150 includes a first portion 151 on the top surface 144t of the top microstructure 144 and a second portion 152 on the sidewall 144s of the top microstructure 144. The height H1 of the first portion 151 is greater than the width W1 of the second portion 152. The anti-reflection layer 150 is partially connected above adjacent top microstructures 144, and air cavities AG surrounded by the anti-reflection layer 150 are defined between adjacent top microstructures 144. More specifically, the first portion 151 of the anti-reflection layer 150 is connected above the air cavities AG, while the second portion 152 of the anti-reflection layer 150 is separated by the air cavities AG.

[0106] Reference Figures 9 to 11 , which are enlarged cross-sectional views of different embodiments of the image sensor according to the present disclosure. In some embodiments, as Figure 9 As shown, image sensor 100 further includes a protective layer 170 disposed on anti-reflection layer 150. The refractive index of anti-reflection layer 150 is greater than that of protective layer 170, and the refractive index of protective layer 170 is greater than 1. In some embodiments, protective layer 170 provides a flat upper surface to facilitate subsequent processing.

[0107] Or, as Figure 10 As shown, image sensor 100 further includes a top index-matching layer 180 disposed between antireflection layer 150 and top surface 144t of top microstructure 144. The refractive index of metalayer 140 is greater than that of top index-matching layer 180, and the refractive index of top index-matching layer 180 is greater than or equal to that of antireflection layer 150. In some embodiments, top index-matching layer 180 is disposed between antireflection layer 150 and top surface 144t of top microstructure 144, while sidewalls 144s of top microstructure 144 directly contact antireflection layer 150. The sum of height H1 of first portion 151 of antireflection layer 150 and thickness T1 of top index-matching layer 180 is greater than height H2 of third portion 153 of antireflection layer 150.

[0108] Alternatively, as shown in FIG. 1C, the shape of the first portion 151 of the anti-reflective layer 150 can be trimmed to be rounded or a rounded head. In some embodiments, the superstrate 140 further comprises a bottom microstructure 145 protruding from the liner layer 142 in a direction opposite to the direction D1 of the top microstructure 144. The bottom microstructure 145 can be aligned with the top microstructure 144, or the bottom microstructure 145 can be misaligned with the top microstructure 144. Figure 11

[0109] Optionally, the image sensor 100 further comprises a bottom index matching layer 190 disposed between the buffer layer 130 and the bottom surface 142b of the liner layer 142 of the superstrate 140. The superstrate 140 has a refractive index greater than that of the bottom index matching layer 190, and the bottom index matching layer 190 has a refractive index greater than or equal to that of the buffer layer 130. In some embodiments, the thickness T2 of the bottom index matching layer 190 is less than or equal to the thickness T1 of the top index matching layer 180. In some embodiments, the bottom surface 145b of the bottom microstructure 145 is in direct contact with the buffer layer 130.

[0110] Referring to FIGS. 1A-1C, cross-sectional views of different embodiments of an image sensor according to the present disclosure are shown. As shown in FIG. 1A, the image sensor 100 comprises a photoelectric conversion layer 110, a color filter layer 120 disposed on the photoelectric conversion layer 110, a buffer layer 130 disposed on the color filter layer 120, a superstrate 140 disposed on the buffer layer 130, and an anti-reflective layer 150 covering the superstrate 140. Figures 12 to 15 Figure 12 The superstrate 140 comprises a liner layer 142 disposed on the buffer layer 130, and a plurality of top microstructures 144 protruding from the liner layer 142 in a direction D1 away from the photoelectric conversion layer 110. The superstrate 140 further comprises a bottom microstructure 145 protruding from the liner layer 142 in a direction D3. The bottom microstructure 145 can be aligned with the top microstructure 144, or the bottom microstructure 145 can be misaligned with the top microstructure 144.

[0111] The superstrate 140 comprises a liner layer 142 disposed on the buffer layer 130, and a plurality of top microstructures 144 protruding from the liner layer 142 in a direction D1 away from the photoelectric conversion layer 110. The superstrate 140 further comprises a bottom microstructure 145 protruding from the liner layer 142 in a direction D3. The bottom microstructure 145 can be aligned with the top microstructure 144, or the bottom microstructure 145 can be misaligned with the top microstructure 144.

[0112] ​​In some embodiments, the dimensions of the top microstructures 144 and bottom microstructures 145, the spacing between the top microstructures 144 and bottom microstructures 145, and / or the distribution density of the top microstructures 144 and bottom microstructures 145 within a single color filter segment 122 can be varied based on different optical design requirements. The anti-reflection layer 150 non-conformally covers the top surface of the top microstructures 144 of the metalayer 140. In some embodiments, the aspect ratio (height / width) of the anti-reflection layer 150 on different top microstructures 144 can vary based on optical design requirements.

[0113] Image sensor 100 further includes a top index-matching layer 180 disposed between antireflection layer 150 and top surface 144t of top microstructure 144, and a bottom index-matching layer 190 disposed between buffer layer 130 and bottom surface 142b of liner layer 142 of metalayer 140. In some embodiments, the refractive index of metalayer 140 is greater than that of top index-matching layer 180, and the refractive index of top index-matching layer 180 is greater than or equal to that of antireflection layer 150, and the refractive index of antireflection layer 150 is greater than 1. The refractive index of metalayer 140 is greater than that of bottom index-matching layer 190, and the refractive index of bottom index-matching layer 190 is greater than or equal to that of buffer layer 130.

[0114] like Figure 13 As shown, image sensor 100 includes a double-layer metamorphic layer. Image sensor 100 further includes an inner metamorphic layer 200 disposed within buffer layer 130. Inner metamorphic layer 200 is disposed below metamorphic layer 140. In some embodiments, inner metamorphic layer 200 includes a lining layer 202, a plurality of inner top microstructures 204 protruding from lining layer 202 in a direction D1 away from photoelectric conversion layer 110, and a plurality of inner bottom microstructures 206 protruding from lining layer 202 in a direction D3 toward photoelectric conversion layer 110. The inner top microstructures 204 and inner bottom microstructures 206 in inner metamorphic layer 200 can have the same arrangement as the top microstructures 144 and bottom microstructures 145 in metamorphic layer 140.

[0115] The image sensor 100 further includes an inner top refractive index matching layer 210 disposed between the buffer layer 130 and the top surface 204t of the inner top microstructure 204 of the inner metalayer 200. The image sensor 100 further includes an inner bottom refractive index matching layer 220 disposed between the buffer layer 130 and the bottom surface 202b of the liner layer 202 of the inner metalayer 200.

[0116] like Figure 14As shown, the designs of the anti-reflection layer 150 and the top refractive index matching layer 180 on a single color filter segment can be different. For example, the metalayer 140 includes a first top microstructure 146 and a second top microstructure 148 on a single color filter segment 122a. The top refractive index matching layer 180 is disposed between the anti-reflection layer 150 and the top surface 146t of the first top microstructure 146, while the anti-reflection layer 150 directly contacts the top surface 148t of the second top microstructure 148.

[0117] In some embodiments, the antireflection layer 150 includes a fourth portion 154 on the top surface 148 t of the second top microstructure 148 , and the sum of the thickness T1 of the top index matching layer 180 and the height H1 of the first portion 151 is greater than the height H3 of the fourth portion 154 .

[0118] like Figure 15 As shown, the designs of the anti-reflection layer 150 and the top refractive index matching layer 180 on different color filter segments can be different. For example, the metalayer 140 includes a first top microstructure 146 on the first color filter segment 122a and a second top microstructure 148 on the second color filter segment 122b. The filtering band of the first color filter segment 122a is different from the filtering band of the second color filter segment 122b.

[0119] The top refractive index matching layer 180 is disposed between the anti-reflection layer 150 and the top surface 146 t of the first top microstructure 146 , while the anti-reflection layer 150 is directly in contact with the top surface 148 t of the second top microstructure 148 .

[0120] In some embodiments, the antireflection layer 150 includes a fourth portion 154 on the top surface 148 t of the second top microstructure 148 , and the sum of the thickness T1 of the top index matching layer 180 and the height H1 of the first portion 151 is greater than the height H3 of the fourth portion 154 .

[0121] In some embodiments of the present disclosure, an image sensor includes a metamaterial layer having multiple microstructures on a photoelectric conversion layer, and an antireflection layer on the metamaterial layer to reduce the reflectivity of the microstructures. The antireflection layer non-conformally covers the metamaterial layer to further reduce the reflectivity of the microstructures and improve the optical performance of the image sensor.

[0122] Although the present disclosure has been disclosed above with reference to the embodiments, they are not intended to limit the present disclosure. Anyone skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the appended claims.

Claims

1. An image sensor, characterized in that: Include: a photoelectric conversion layer; a color filter layer disposed on the photoelectric conversion layer; a buffer layer disposed on the color filter layer; a metalayer comprising a liner layer disposed on the buffer layer and a plurality of top microstructures on the liner layer, wherein the top microstructures protrude from the liner layer in a direction away from the photoelectric conversion layer; and An anti-reflection layer covers the metalayer, wherein the anti-reflection layer includes a first portion and a second portion, the first portion is located on a top surface of a first top microstructure among the top microstructures, the second portion is located on a sidewall of the first top microstructure, and a height of the first portion is greater than a width of the second portion.

2. The image sensor of claim 1 , wherein the height is measured at a center of the top surface of the first top microstructure along the direction away from the photoelectric conversion layer, and the width is measured at a midpoint of the sidewall of the first top microstructure along a direction perpendicular to the direction away from the photoelectric conversion layer.

3. The image sensor of claim 1 , wherein the anti-reflection layer includes a third portion located on the top surface of the liner layer, and a height of the third portion is greater than the width of the second portion, a ratio of the height of the first portion to the width of the second portion is greater than or equal to 1.2, and a ratio of the height of the third portion to the width of the second portion is greater than or equal to 1.

3.

4. The image sensor of claim 1 , wherein the anti-reflection layer includes a third portion located on the top surface of the liner layer, and a height of the third portion is greater than the width of the second portion, a ratio of the height of the first portion to the width of the second portion is greater than or equal to 1.5, and a ratio of the height of the third portion to the width of the second portion is greater than or equal to 1.

7. 5 . The image sensor as claimed in claim 1 , wherein the first portion has a rounded corner, and a curvature radius of the rounded corner is smaller than the height of the first portion. 6 . The image sensor of claim 1 , wherein the first portion has a round head portion protruding laterally from the second portion.

7. The image sensor of claim 1 , wherein the anti-reflection layer is partially connected to adjacent top microstructures, and an air cavity surrounded by the anti-reflection layer is disposed between adjacent top microstructures. The image sensor further comprises a protective layer disposed on the anti-reflection layer, wherein the refractive index of the anti-reflection layer is greater than that of the protective layer, and the refractive index of the protective layer is greater than 1.

8. The image sensor of claim 1, further comprising: a top refractive index matching layer disposed between the antireflection layer and the top surface of the first top microstructure, the refractive index of the metalayer being greater than the refractive index of the top refractive index matching layer, and the refractive index of the top refractive index matching layer being greater than or equal to the refractive index of the antireflection layer; and A bottom refractive index matching layer is disposed between the buffer layer and a bottom surface of the liner layer, wherein the refractive index of the metalayer is greater than the refractive index of the bottom refractive index matching layer, and the refractive index of the bottom refractive index matching layer is greater than or equal to the refractive index of the buffer layer, wherein the thickness of the bottom refractive index matching layer is less than or equal to the thickness of the top refractive index matching layer.

9. The image sensor of claim 1 , further comprising a top refractive index matching layer disposed between the anti-reflection layer and the top surface of the first top microstructure, wherein the anti-reflection layer directly contacts a top surface of a second top microstructure among the top microstructures, wherein the first top microstructure and the second top microstructure are located in the same color filter region of the color filter layer.

10. The image sensor of claim 1 , further comprising a top refractive index matching layer disposed between the anti-reflection layer and the top surface of the first top microstructure, wherein the anti-reflection layer directly contacts a top surface of a second top microstructure among the top microstructures, wherein the first top microstructure and the second top microstructure are respectively located in different color filter regions of the color filter layer.

11. The image sensor of claim 1 , further comprising a top refractive index matching layer disposed between the anti-reflection layer and the top surface of the first top microstructure, wherein the anti-reflection layer directly contacts a top surface of a second top microstructure among the top microstructures, wherein the anti-reflection layer comprises a fourth portion disposed on the top surface of the second top microstructure, and a sum of a thickness of the top refractive index matching layer and the height of the first portion is greater than a height of the fourth portion.

12. The image sensor of claim 1 , wherein the anti-reflection layer comprises a fourth portion and a fifth portion, the fourth portion being disposed on a top surface of a second top microstructure among the top microstructures, and the fifth portion being disposed on a sidewall of the second top microstructure, a height of the fourth portion being greater than a width of the fifth portion, and a first ratio of the height of the first portion to the width of the second portion being greater than a second ratio of the height of the fourth portion to the width of the fifth portion.

13. The image sensor of claim 1, wherein The refractive index of the metalayer is greater than the refractive index of the anti-reflection layer, and the refractive index of the anti-reflection layer is greater than 1; and The metamaterial layer includes a plurality of bottom microstructures, the bottom microstructures protrude from the liner layer in a direction toward the photoelectric conversion layer, and the bottom microstructures are staggered with the top microstructures; The image sensor further includes: an inner metalayer disposed on the buffer layer; an inner top refractive index matching layer disposed between the buffer layer and a top surface of a top microstructure in the inner metalayer; and An inner bottom refractive index matching layer is disposed between the buffer layer and a bottom surface of a liner layer in the inner metalayer.

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