Image sensor and its manufacturing process
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- VISERA TECH CO LTD
- Filing Date
- 2023-06-09
- Publication Date
- 2026-06-26
Abstract
Description
Description Title of the invention: Image sensor and method of manufacturing the same this one Technical field
[0001] — The present description relates to an image sensor and a method of manufacturing the same. image sensor. Prior art
[0002] — In the field of complementary metal-oxide-semiconductor image sensors (CMOS) (which can also be called CIS), a lens array can be arranged above photosensitive elements to receive external light. However, an etching process can damage a substrate under a material of lens during the formation of the lens matrix. In addition, elements arranged above the lens array can cause stress imbalance between the elements and the lens matrix, from which it results that a deflection of the slice may occur. Therefore, it is necessary to resolve the issues previous. Summary of the invention
[0003] = The method of manufacturing an image sensor of the present description may solve the previously mentioned problems in the manufacturing process, thus improving the performance of the image sensor.
[0004] — The image sensor of the present disclosure has a gentler tilt for resolve a constraint imbalance at the boundary between a matrix of lenses and elements disposed above the lens array.
[0005] One aspect of the present disclosure is to provide a method of manufacturing a image sensor. The manufacturing process involves the following steps. A substrate is provided. A lens layer is formed above the substrate. A layer of patterned hard mask is formed on the lens layer. The lens layer is etched to transfer a pattern from the patterned hard mask layer onto the patterned hard mask layer. lens such that a plurality of lenses are defined, wherein the lenses are microlenses or meta-surface lenses. A coating layer is formed to cover the plurality of lenses and the substrate. Portions of the layer of coating are etched to form a first inclined side wall and a second inclined side wall, wherein the second inclined side wall is au- above the first inclined side wall, in which an extension of the first inclined side wall on the substrate is spaced by an extension of the second wall inclined side on the substrate. A bandpass filter layer having several films are formed conformally on the coating layer and cover the substrate. According to some embodiments of the present disclosure, before forming the lens layer above the substrate, the method further comprises the following steps. A photoresist layer with a third inclined sidewall and having a trench on the substrate is formed. The lens layer with a fourth inclined sidewall is formed in the trench. The photoresist layer is removed, wherein an angle between the third inclined sidewall and an upper surface of the substrate is greater than 90 degrees, and an angle between the fourth inclined sidewall and the upper surface of the substrate is less than 90 degrees. According to some embodiments of the present disclosure, after forming the lens layer above the substrate, the method further comprises the following steps. A filler layer is formed on the substrate and surrounds the lens layer, wherein a top surface of the lens layer is substantially co-planar with a top surface of the filler layer. The patterned hard mask layer is formed on the filler layer. The filler layer is etched to transfer the pattern of the patterned hard mask layer onto the filler layer, such that a remaining portion of the filler layer and an underlying layer are defined, wherein the underlying layer is disposed between the plurality of lenses and the substrate, and the underlying layer is connected to the remaining portion. According to some embodiments of the present disclosure, after defining the remaining portion of the filler layer and the underlying layer, the method further comprises the following steps. A protective layer is formed to cover the plurality of lenses and to expose the remaining portion of the filler layer. The remaining portion of the filler layer is removed. The protective layer is removed. An antireflective film is formed on upper surfaces of the plurality of lenses. According to some embodiments of the present disclosure, after defining the remaining portion of the filler layer and the underlying layer, the method further comprises the following steps. A protective layer is formed to cover the plurality of lenses and a first portion of the remaining portion of the filler layer, wherein a second portion of the remaining portion of the filler layer is exposed. The second portion of the remaining portion of the filler layer is removed. The protective layer is removed. An antireflection film is formed on upper surfaces of the plurality of lenses and an upper surface of the first portion of the remaining portion of the filler layer. According to certain embodiments of the present disclosure, prior to the formation of the lens layer above the substrate, an underlying layer is formed on the substrate. According to some embodiments of the present disclosure, during the step of forming the coating layer to cover the plurality of lenses and the substrate and the step of etching portions of the coating layer to form the first inclined sidewall and the second inclined sidewall, the method further comprises the following steps. A first coating layer is formed to cover the plurality of lenses and the substrate. A portion of the first coating layer is etched to expose a portion of the substrate and to form a third inclined sidewall. A second coating layer is formed over the first coating layer and the portion of the substrate to form the first inclined sidewall on a top of the coating layer. A portion of the second coating layer is etched to form the second inclined sidewall on a bottom of the coating layer. According to some embodiments of the present disclosure, an angle between the second inclined sidewall and a top surface of the substrate is in a range of 20 degrees to 60 degrees, and an angle between the third inclined sidewall and the top surface of the substrate is in a range of 20 degrees to 60 degrees. According to some embodiments of the present disclosure, during the step of etching portions of the cladding layer to form the first inclined wall and the second inclined wall, the method further comprises the following steps. A first portion of the cladding layer is etched to form the first inclined sidewall on a top of the cladding layer, wherein an angle between the first inclined sidewall and a top surface of the substrate is in a range of 20 degrees to 60 degrees. A second portion of the cladding layer is etched to form the second inclined sidewall on a bottom of the cladding layer, wherein an angle between the second inclined sidewall and the top surface of the substrate is in a range of 20 degrees to 60 degrees. One aspect of the present disclosure is to provide an image sensor. The image sensor comprises a substrate, a plurality of lenses, a coating layer, and a bandpass filter layer. The plurality of lenses are disposed on the substrate, wherein the plurality of lenses are microlenses or metasurface lenses. The coating layer is disposed on the plurality of lenses and the substrate. The coating layer has a first inclined sidewall and a second inclined sidewall, and the first inclined sidewall is above the second inclined sidewall. An extension of the first inclined sidewall on the substrate is separated from an extension of the second inclined sidewall on the substrate. The bandpass filter layer having multiple films is conformally deposited on the coating layer and covers the substrate. According to some embodiments of the present disclosure, the image sensor further comprises an anti-reflective film disposed on upper surfaces of the lenses. According to some embodiments of the present disclosure, the image sensor further comprises a filler layer disposed on the substrate and surrounding the plurality of lenses, wherein a thickness of the filler layer is in a range of 0.1 um to 100 um. According to some embodiments of the present disclosure, the image sensor further comprises an anti-reflective film disposed on upper surfaces of the lenses and an upper surface of the filler layer. According to some embodiments of the present disclosure, the image sensor further comprises an underlying layer disposed between the plurality of lenses and the substrate, wherein a thickness of the underlying layer is in a range of 0.01 µm to 100 µm. According to some embodiments of the present disclosure, a lens material is a-Si, SiH, GeH, Ge, GeO, or GeSiH. According to some embodiments of the present disclosure, a material of the underlying layer is different from a material of the lenses. According to some embodiments of the present disclosure, a material of the underlying layer is the same as a material of the lenses, and a thickness of the underlying layer is in a range of 0.01 µm to 100 µm. According to some embodiments of the present disclosure, a distance between an outermost portion of the second inclined sidewall and an outermost portion of the underlying layer is in a range of 40 µm to 100 µm. According to some embodiments of the present disclosure, when the plurality of lenses are microlenses, an extension of the microlenses on the substrate is within an extension of the underlying layer on the substrate. According to some embodiments of the present disclosure, an angle between the first inclined sidewall and a top surface of the substrate is in a range of 20 degrees to 60 degrees, wherein an angle between the second inclined sidewall and the top surface of the substrate is in a range of 20 degrees to 60 degrees. Brief description of the drawings Aspects of this description will be better understood from the following detailed description, read in conjunction with the accompanying figures. It will be noted that, in accordance with common industry practice, various features are not drawn to scale. In In practice, the dimensions of the various elements can be arbitrarily increased or reduced for clarity of presentation. Figures 1A to 1L are a succession of cross-sectional views of a method of manufacturing an image sensor according to certain embodiments of the present disclosure. Figures 2A-2C are a succession of cross-sectional views of a fabrication of a coating layer of the image sensor of [Fig. 1L] according to alternative embodiments of the present disclosure. Figures 3A to 3F are a succession of cross-sectional views of a method of manufacturing an image sensor according to certain embodiments of the present disclosure. [Fig.4] is a cross-sectional view of an image sensor according to the manufacturing method shown in Figures 3A to 3F. Figures 5A to 5F are a succession of cross-sectional views of a method of manufacturing an image sensor according to certain embodiments of the present disclosure. [Fig.6] is a cross-sectional view of an image sensor according to the manufacturing method shown in Figures 5A to 5F. Figures 7A to 7E are a succession of cross-sectional views of a method of manufacturing an image sensor according to certain embodiments of the present disclosure. [Fig. 8] is a cross-sectional view of an image sensor according to the manufacturing method shown in Figures 7A to 7E. Figures 9-11 are cross-sectional views of image sensors according to certain embodiments of the present disclosure. [Fig.12] is a top view of a region of the image sensor shown in [Fig.8]. Figures 13A, 13B and 13C are top views of a meta-surface lens of [Fig.12]. Description of the embodiments The following description provides many different embodiments, or examples, for implementing different features of the proposed subject matter. Particular examples of components and arrangements are described below to simplify this description. These are, of course, examples only and are not intended to be limiting. For example, the formation of a first element on or under a second element in the following description may include embodiments in which the first and second elements are formed in contact direct and may also include embodiments in which additional elements may be formed between the first and second elements, such that the first and second elements may not be in direct contact. In addition, this description may repeat numerical and / or alphabetical references in the various examples. This repetition is for the purpose of simplification and clarification and does not, in itself, impose a relationship between the various embodiments and / or configurations discussed. It should be noted that although the terms first, second, etc. may be used herein to describe various elements, those elements should not be limited by those terms. These terms are used only to differentiate one element from another. For example, a first element could be called a second element and, similarly, a second element could be called a first element, without departing from the scope of the embodiments. As used herein, the phrase "and / or" includes any and all combinations of one or more of the related elements listed. In addition, spatial terms such as “under,” “below,” “lower,” “upper,” and the like may be used herein for convenience of description to describe a relationship of one element or feature to another element(s) or feature(s) as shown in the figures. The spatial terms are intended to encompass various orientations of the device in use or operation in addition to the orientation shown in the figures. The apparatus may be oriented otherwise (rotated 90 degrees or in some other orientation) and the spatial descriptors used herein may similarly be interpreted in corresponding ways. The present invention describes 7 embodiments of image sensors (shown in Figures 1L, 4, 6 and 8 to 11) and two types of lenses in these 7 embodiments which are microlenses or meta-surface lenses. In the image sensors of Figures 1L, 4 and 6, the lenses 180 are microlenses. In the image sensors of Figures 8 to 11, the lenses 750 are meta-surface lenses. Embodiments of the methods and structures of the present disclosure will be described in detail below. It should be noted that additional steps may be provided before, during, and after processes represented by the following figures, and some of the steps described below may be replaced or deleted for additional embodiments of the process. The order of the steps may be changed. Figures 1A to 1L are a succession of cross-sectional views of a method of manufacturing an image sensor 1000A according to certain embodiments of the present disclosure. As shown in [Fig. 1 A], a substrate 110 is provided and includes a photosensitive circuit array integrated in the substrate 110. The photosensitive circuit array includes a plurality of photosensitive elements 112. The photosensitive element 112 may be a photodiode or single-photon avalanche diodes (SPADs), but is not limited to this. The photosensitive circuit array is configured to detect external light. A photoresist layer 120 is disposed on the substrate 110 and a trench 130 is formed in the photoresist layer 120. In other words, the substrate 110 and the photoresist layer 120 form the trench 130. Note that the photoresist layer 120 and the trench 130 define a lens array area AA in which a plurality of lenses (including microlenses or meta-surface lenses) will be formed, and a peripheral region PA is a lens-free region. As shown in [Fig. 1A], the photoresist layer 120 has an obtuse angle θ1 between an inclined sidewall 122 of the photoresist layer 120 and an upper surface 114 of the substrate 110 such that the inclined sidewall 122 faces the upper surface 114 of the substrate 110. The obtuse angle θ1 is greater than 90 degrees. In some embodiments, a material of the photoresist layer 120 may be a positive-type photoresist or a negative-type photoresist. In one embodiment, the pattern of the photoresist layer 120 may be formed by a lithography process. The inclined sidewall 122 may be formed by adjusting the photolithography focal length, but is not limited to this. As shown in |Fig.1A] and in |Fig.1B], a lens layer 140 is formed above the substrate 110. In particular, a first portion 140a of the lens layer 140 is formed on the upper surface 114 of the substrate 110, and a second portion 140b of the lens layer 140 is formed on an upper surface 124 of the photoresist layer 120, such that a trench 150 is formed above the substrate 110. Note that the first portion 140a and the second portion 140b of the lens layer 140 are formed simultaneously. In some embodiments, a thickness of the first portion 140a is the same as a thickness of the second portion 140b. In some embodiments, the lens layer 140 may be formed by physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or another suitable deposition process.During the deposition process of the lens layer 140, the photosensitive resin layer 120 can be used as advances so that the first portion 140a of the lens layer 140 has a sloped sidewall 142. The first portion 140a has an acute angle 02 between the sloped sidewall 142 of the first portion 140a and the upper surface 114 of the substrate 110 so that the sloped sidewall 142 is . facing the inclined sidewall 122. The acute angle 02 is less than 90 degrees. The first portion 140a is trapezoidal in shape. In some embodiments, a slope of the inclined sidewall 122 is greater than a slope of the inclined sidewall 142. As shown in [Fig.1B], an air gap is present between the inclined sidewall 122 and the inclined sidewall 142. In some embodiments, the lens layer 140 is formed by an inorganic material including a-Si, SiH, GeH, Ge, GeO, GeSiH or another suitable material. As shown in [Fig. 1B] and [Fig. 1C], the photoresist layer 120 and the second portion 140b of the lens layer 140 are removed from the peripheral area PA. In some embodiments, the removal process is performed by a peeling process. In particular, the structure shown in [Fig. 1B] is dipped into an aqueous solution that has a relatively high solubility or swelling capacity for the photoresist layer 120 compared to the lens layer 140. Therefore, the first portion 140a of the lens layer 140 is held on the substrate 110. The peeling process of the present disclosure can reduce film stress to avoid stress imbalance and wafer flexing. As shown in [Fig. 1C] and [Fig. 1D], a filler layer 160 is formed on the substrate 110 and surrounds the first portion 140a of the lens layer 140. In other words, the filler layer 160 fills the area lacking the first portion 140a of the lens layer 140. An upper surface 144 of the first portion 140a of the lens layer 140 is substantially coplanar with an upper surface 162 of the filler layer 160. In particular, the filler layer 160 covers and contacts the inclined sidewall 142 of the lens layer 140. In some embodiments, a material of the filler layer 160 may be a photoresist, such as a transparent photoresist. In some embodiments, the pattern of the filler layer 160 may be achieved by a lithography process.The lithography process achieves a planar topography such that the lens layer 140 has a uniform first portion 140a. A deposition thickness of the filler layer 160 may be adjusted depending on the thickness of the first portion 140a of the lens layer 140. As shown in [Fig. 1D] and [Fig. 1E], a patterned hard mask layer 170 is formed on the first portion 140a of the lens layer 140. In particular, the patterned hard mask layer 170 has a first portion 170a having hemispherical profiles and a second portion 170b under the first portion 170a. The second portion 170b is a planar film disposed on the upper surface 144 of the first portion 140a of the lens layer 140 and the upper surface 162 of the filler layer 160. The first portion 170a of the patterned hard mask layer 170 has a surface profile of a microlens array. In some embodiments, a material of the patterned hard mask layer 170 may be a photoresist. In some embodiments, the pattern of the patterned hard mask layer 170 may be formed by a lithography process. In some embodiments, the positions of the first portion 170a may be defined first, and then the hemispherical profiles formed. As shown in [Fig.1E], each of the hemispherical profiles of the patterned hard mask layer 170 corresponds to each of the photosensitive elements 112.It will be noted that the number of hemispherical profiles and the number of photosensitive elements 112 are shown primarily for clarification and are not intended to limit the present description. As shown in [Fig. 1E] and [Fig. 1F], the lens layer 140 is etched to transfer a pattern of the patterned hard mask layer 170 (including the first portion 170a and the second portion 170b) onto the lens layer 140 such that a plurality of lenses 180 are defined. The lens layer 140 is etched by an etching process E. In particular, during the etching process E, the filler layer 160 is also etched to transfer the pattern of the second portion 170b of the patterned hard mask layer 170 onto the filler layer 160 such that the plurality of lenses 180 have an underlying layer 182 and a remaining portion 160a of the filler layer 160 is defined. The underlying layer 182 is disposed between the lenses 180 and the substrate 110.The underlying layer 182 is disposed between the lenses 180 and the substrate 110 and the underlying layer 182 is connected to the remaining portion 160a of the filler layer 160. Since the lenses 180 and the underlying layer 182 are formed by etching the lens layer 140, the materials of the lenses 180 and the underlying layer 182 are the same as the material of the lens layer 140, for example, an inorganic material (such as a-Si, SiH, GeH, Ge, GeO or GeSiH). In such an embodiment, the filler layer 160 and the underlying layer 182 may also be used as protective layers to prevent the substrate 110 underneath from being damaged during the etching process E. In some embodiments, the etching process E is a dry etching process. In some embodiments, a thickness of the remaining portion 160a of the filler layer 160 is in a range from 0.1 µm to 100 µm, for example, 10, 20, 50, or 80 µm. A thickness of the underlying layer 182 may be adjusted by the focal length during the etching process E. In some embodiments, the thickness of the underlying layer 182 is in a range from 0.01 µm to 100 µm, for example, 0.1, 1, 10, 20, 50, or 80 µm. In some embodiments, the thickness of the remaining portion 160a is similar to a thickness of the underlying layer 182. In some embodiments, the thickness of the remaining portion 160a is the same as the thickness of the underlying layer 182. In some embodiments, the thickness of the remaining portion 160a is slightly thinner than the thickness of the underlying layer 182. Still referring to [Fig. 1F]. The underlying layer 182 is a planar film disposed on the upper surface 114 of the substrate 110. The lenses 180, the underlying layer 182, and the remaining portion 160a are all disposed on the upper surface 114 of the substrate 110. In this embodiment, the lenses 180 are microlenses. In some embodiments, a diameter / width of the microlenses 180 is in a range from 1 µm to 100 µm. In some embodiments, a height H of the microlenses 180 is in a range from 0.1 µm to 50 µm. Since the patterned hard mask layer 170 has the surface profile of the microlens array, the lenses 180 also have the surface profile of the microlens array. The lenses 180 are arranged above the photosensitive elements 112 and each of the lenses 180 corresponds to each of the photosensitive elements 112. Referring again to [Fig. 1E], an extension P1 of the first portion 170a of the patterned hard mask layer 170 on the substrate 110 is within an extension P2 of the first portion 140a of the lens layer 140 on the substrate 110. The extension P2 of the first portion 140a of the lens layer 140 on the substrate 110 overlaps an extension P3 of the filler layer 160 on the substrate 110. As shown in [Fig. 1F], the underlying layer 182 protrudes from the bottoms of the peripheral lenses 180. In other words, an extension P4 of the lenses 180 on the substrate 110 is within an extension P5 of the underlying layer 182 on the substrate 110. Figures 1G to 1L are a succession of cross-sectional views of the manufacturing process of the image sensor 1000A after [Fig. 1F]. Note that the lens array area AA is always an area that includes a plurality of lenses (including microlenses or meta-surface lenses), and the peripheral area PA is an area without a lens. As shown in [Fig. 1F] and [Fig. 1G], a coating layer 192 is formed to cover the plurality of lenses 180 and the substrate 110. In particular, the coating layer 192 is arranged in both the lens array area AA and the peripheral area PA. The coating layer 192 covers upper surfaces 184 of the lenses 180, an upper surface 162 and a side surface 164 of the remaining portion 160a and the upper surface 114 of the substrate 110. The coating layer 192 has a planar upper surface 193. As shown in [Fig.1G] and [Fig. 1H], part of the cladding layer 192 is etched to expose a portion 110a of the substrate 110 and to form the inclined sidewall 194. In some embodiments, the inclined sidewall 194 is formed by a lithography process and an etching process. In some embodiments, an angle θ3 between the inclined sidewall 194 and the top surface 114 of the substrate 110 is in a range of 20 degrees to 60 degrees, such as 30, 40, or 50 degrees. In some embodiments, a distance D1 between an outermost portion of the inclined sidewall 194 and an outermost portion of the underlying layer 182 is in a range of 20 μm to 50 μm, for example 30 or 40 μm. Note that "outermost portion" here is a direction toward the peripheral area PA. As shown in [Fig. 1H] and [Fig. 11], a coating layer 196 is formed on the coating layer 192 and the portion 110a of the substrate 110 to form a sloped sidewall 197 on a top of the coating layer 192. In particular, the coating layer 196 is a liner on the coating layer 192 such that the coating layer 196 has the sloped sidewall 197 above the sloped sidewall 194 of the coating layer 192. As shown in [Fig. 1I] and [Fig. 1J], a portion of the cladding layer 196 is etched to form the sloped sidewall 198 on a background of the cladding layer 196. In some embodiments, the sloped sidewall 198 is formed by a lithography process and an etching process. The sloped sidewall 197 is above the sloped sidewall 198. In some embodiments, an angle θ4 between the sloped sidewall 198 and a top surface 114 of the substrate 110 is in a range of 20 degrees to 60 degrees, for example, 30, 40, or 50 degrees. In some embodiments, a distance D2 between an outermost portion of the inclined sidewall 198 and an outermost portion of the inclined sidewall 197 is in a range from 20 µm to 50 µm, for example, 30 or 40 µm.In some embodiments, a distance D3 between the outermost portion of the inclined sidewall 198 and the outermost portion of the underlying layer 182 is in a range of 40 µm to 100 µm, for example 50, 60, 70, 80 or 90 µm. In some embodiments, an extension P6 of the inclined sidewall 197 of the cladding layer 196 on the substrate 110 is spaced from an extension P7 of the inclined sidewall 198 of the cladding layer 196 on the substrate 110. In some embodiments, a width of the cladding layer 196 is greater than a width of the cladding layer 192. In some embodiments, a material of the cladding layer 192 and / or the cladding layer 196 may be a dielectric or a transparent polymer, such as a resin, spun glass, silicon dioxide, etc. In other words, each of the coating layer 192 and the coating layer 196 may be a polymer layer and / or a dielectric layer. In some embodiments, the coating layer 192 and / or the coating layer 196 may be formed by an ion implantation process or another suitable coating process. As shown in [Fig.1J] and [Fig.1K], a photoresist layer 2000 and a bandpass filter layer 2100 are formed on the substrate 110. In particular, the bandpass filter 2100 has a first portion 2100a and a second portion 2100b. The first portion 2100a of the bandpass filter layer 2100 is conformally disposed on the coating layer 196 and the upper surface 114 of the substrate 110. The second portion 2100b of the bandpass filter layer 2100 is disposed on the photoresist layer 2000. The first portion 2100a surrounds and seals the coating layer 196. In some embodiments, a material of the photoresist layer 2000 may be a positive-type photoresist or a negative-type photoresist.In some embodiments, the pattern of the photoresist layer 2000 may be formed by a lithography process. The photoresist layer 2000 has an obtuse angle between a sloped sidewall 2002 of the photoresist layer 2000 and the top surface 114 of the substrate 110. Referring again to [Fig. 1K], note that the first portion 2100a and the second portion 2100b of the bandpass filter layer 2100 are formed at the same time. The bandpass filter layer 2100 comprises several films and each film may be formed by PVD or another suitable deposition process. In some embodiments, a material of the bandpass filter layer 2100 comprises a-Si, SiO2, Nb205, GeO2, TiO2, etc. During the deposition process of the bandpass filter layer 2100, the photoresist layer 2000 can be used as an advancer so that the first portion 2100a adjacent to the photoresist layer 2000 has a sloped sidewall 2102. The first portion 2100a has an acute angle between the sloped sidewall 2102 of the first portion 2100a and the upper surface 114 of the substrate 110. As shown in [Fig.1K], an air gap is present between the inclined side wall 2102 and the inclined side wall 2002. The structure of the bandpass filter layer 2100 can be adjusted according to the operating wavelength of the image sensor. As shown in [Fig. 1K] and [Fig. 1L], in some embodiments, the photoresist layer 2000 and the second portion 2100b of the bandpass filter layer 2100 are removed by a peeling process. Accordingly, the image sensor 1000A having microlenses 180, the underlying layer 182 and the remaining portion 160a of the filling layer 160 are formed, as shown in [Fig.1L]. The lenses 180 are configured to receive external light. In some embodiments, a refractive index of the coating layer 196 and / or the coating layer 192 is in a range of 1.1 to 1.6, for example 1.2, 1.3, 1.4 or 1.5. In some embodiments, a refractive index of the lenses 180 is in a range of 1.7 to 4.5, for example 2.5, 3.3 or 3.8. In some embodiments, the refractive index of the coating layer 196 and / or the coating layer 192 is between the refractive index of the lenses 180 and the refractive index of air. The refractive index difference between the coating layer 196 and the lenses 180 is large, thus ensuring good performance of the image sensor 1000A. Since the coating layers have inclined sidewalls, the first portion 2100a of the bandpass filter layer 2100 also has inclined sidewalls. The inclined sidewalls (such as the inclined sidewalls 197, 198) of the coating layers smooth the edges of the coating layers, so that the coating layers are better covered by the bandpass filter layer 2100 that has multiple films. In addition, the inclined sidewalls of the bandpass filter layer 2100 help reduce stress at the boundaries of the multiple films of the bandpass filter layer 2100, thereby avoiding delamination between dissimilar materials.In other words, a thickness of the image sensor 1000A from the lens array area AA to the peripheral area PA is gradually reduced. The image sensor 1000A has a flat topography and can avoid stress imbalance at the edges of the plural films between a microlens array (such as the lenses 180) and elements arranged above the microlens array which would lead to wafer flexure, thus ensuring good optical performance. Figures 2A to 2C are a succession of cross-sectional views of the manufacture of a coating layer of the sensor 1000A of [Fig. 1L] according to alternative embodiments of the present description. In particular, the manufacturing steps of Figures 1G to 1J could be replaced by the manufacturing steps of Figures 2A to 2C. As shown in [Fig. 1F] and [Fig. 2A], a coating layer 2300 is formed to cover the plurality of lenses 180 and the substrate 110. A thickness of the coating layer 2300 of [Fig. 2A] may be greater than a thickness of the coating layer 192 of [Fig. 1G]. A material of the coating layer 2300 may be the same as the material of the coating layer 192 and / or the coating layer 196. As shown in [Fig.2A] and [Fig.2B], a portion of the cladding layer 2300 is etched to form a sloped sidewall 2302 on a top of the cladding layer 2300. In some embodiments, an angle θ between the inclined sidewall 2302 and the top surface 114 of the substrate 110 is in a range from 20 degrees to 60 degrees, for example 30, 40 or 50 degrees. In some embodiments, an etch depth d of the inclined sidewall 2302 may be half, one-third or two-thirds of a total thickness of the cladding layer 2300 depending on the length of the inclined sidewall 2302. In some embodiments, a distance D4 between an outermost portion of the inclined sidewall 2302 and the outermost portion of the underlying layer 182 is in a range from 20 μm to 50 μm, for example 30 or 40 μm. As shown in [Fig.2B] and [Fig.2C], a portion of the cladding layer 2300 is etched to form the sloped sidewall 2304 on a background of the cladding layer 2300. In some embodiments, an angle θ between the sloped sidewall 2304 and the top surface 114 of the substrate 110 is in a range of 20 degrees to 60 degrees, for example 30, 40 or 50 degrees. In some embodiments, a distance DS between an outermost portion of the sloped sidewall 2304 and the outermost portion of the sloped sidewall 2302 is in a range of 20 μm to 50 μm, for example 30 or 40 μm. In some embodiments, a distance D6 between the outermost portion of the inclined sidewall 2304 and the outermost portion of the underlying layer 182 is in a range of 40 µm to 100 µm, for example 50, 60, 70, 80 or 90 µm. Referring again to [Fig.2C], the cladding layer 2300 could be comprised of a first cladding layer 2300a and a second cladding layer 2300b. The second cladding layer 2300b is disposed on the first cladding layer 2300a. The first cladding layer 2300a has the inclined sidewall 2304 and the second cladding layer 2300b has the inclined sidewall 2302. A width of the first cladding layer 2300a is greater than a width of the second cladding layer 2300b. The inclined sidewall 2302 of the second cladding layer 2300b is above the inclined sidewall 2304 of the first cladding layer 2300a. An extension P8 of the inclined sidewall 2302 of the second coating layer 2300b on the substrate 110 is spaced from an extension P9 of the inclined sidewall 2304 of the first coating layer 2300a on the substrate 110. After the formation of the coating layer 2300 in [Fig.2C], the execution of the steps of [Fig.1K] to 1L continues so that the image sensor 1000A of [Fig.1L] is formed. The manufacture of the coating layer 196 or the coating layer 2300 of the image sensor 1000A (as well as the image sensors 1000B to 1000C, 8000A to 8000D) may be carried out by the steps of FIGS. 1C to 1J or by the steps of Figures 2A to 2C. The inclined sidewalls of the cladding layer 196 and the cladding layer 2300 may be formed by 2 times a lithography process and 2 times an etching process to smooth the edges of the cladding layer. Therefore, the inclined sidewalls may provide a gentle slope to reduce stress in corners of the plural films of the bandpass filter layer 2100 (see [Fig. 1L]). Figures 3A to 3F are a succession of cross-sectional views of a method for manufacturing an image sensor 1000B according to some embodiments of the present disclosure. [Fig. 4] is a cross-sectional view of the image sensor 1000B according to the manufacturing method shown in Figures 3A to 3F. The method for manufacturing the image sensor 1000B comprises the steps of Figures 1A to 1L and Figures 2A to 2C as previously described, wherein the manufacturing of the coating layer may be carried out by the steps of Figures 1G to 1J or by the steps of Figures 2A to 2C. The reference numerals are repeated herein to show the same or similar features shown in the preceding figures, the preceding description applies equally to the embodiments described below, and its details will not be described again. As shown in [Fig. 1F] and [Fig. 3A], after defining the lenses 180 with the underlying layer 182 and the remaining portion 160a of the filler layer 160, a protective layer 310 is formed to cover the lenses 180 and to expose the remaining portion 160a of the filler layer 160. In particular, the protective layer 310 is formed in the lens array area AA. In some embodiments, the pattern of the protective layer 310 may be formed by a lithography process. In some embodiments, a material of the protective layer 310 may be a positive or negative type photoresist. As shown in [Fig.3A] and [Fig.3B], the remaining portion 160a of the filler layer 160 is removed. The upper surface 114 of the substrate 110 is exposed. In some embodiments, the remaining portion 160a is removed by a dry etching process. As shown in [Fig.3B] and [Fig.3C], the protective layer 310 is removed so that the lenses 180 and the underlying layer 182 are exposed. As shown in [Fig.3C] and [Fig.3D], a photoresist layer 320 is formed on the upper surface 114 of the substrate 110. In particular, the photoresist layer 320 is formed in the peripheral area PA and surrounds the lenses 180 and the underlying layer 182. The photoresist layer 320 has an obtuse angle between an inclined side wall 322 of the photoresist layer 320 and an inclined side wall 322 of the photoresist layer 320. photoresist 320 and the upper surface 114 of the substrate 110. The formation and material of the photoresist layer 320 may be the same or similar to those of the photoresist layer 120 of [Fig. 1 A]. As shown in [Fig. 3D] and [Fig. 3E], an anti-reflective film 330 is formed on the upper surfaces 184 of the lenses 180. In particular, the anti-reflective film 330 has a first portion 330a and a second portion 330b. The first portion 330a is formed on the upper surfaces 184 of the lenses 180, and the second portion 330b is formed on an upper surface 324 of the photoresist layer 320. Note that the first portion 330a and the second portion 330b of the anti-reflective film 330 are formed simultaneously. The anti-reflective film 330 is a thin film that lines the lenses 180. In some embodiments, the anti-reflective film 330 may be formed by physical vapor deposition (PVD) or another suitable deposition process. As shown in [Fig. 3E] and [Fig. 3F], the photoresist layer 320 and the second portion 330b of the antireflection film 330 are removed from the peripheral area PA. In some embodiments, the removal process is implemented by a peeling process. The peeling process of the present disclosure can reduce film stress to avoid stress imbalance and wafer flexing. After forming the lenses 180 with the first portion of the antireflective film 330, execution of the steps of FIGS. 1G to 1L or the steps of FIGS. 2A to 2C continues so that the image sensor 1000B of |Fig.4] is formed. Figures 5A to 5F are a succession of cross-sectional views of a method for manufacturing an image sensor 1000C according to certain embodiments of the present disclosure. [Fig. 6] is a cross-sectional view of the image sensor 1000C according to the manufacturing method shown in Figures 5A to 5F. The method for manufacturing the image sensor 1000C comprises the steps of Figures 1A to 1L and Figures 2A to 2C as previously mentioned, wherein the manufacturing of the coating layer may be carried out by the steps of Figures 1G to 1J or by the steps of Figures 2A to 2C. As shown in [Fig. 1F] and [Fig. 5A], after defining the lenses 180 with the underlying layer 182 and the remaining portion 160a of the filling layer 160, a protective layer 510 is formed to cover the lenses 180 and a first portion 166 of the remaining portion 160a of the filling layer 160, in which a second portion 167 of the remaining portion 160a of the filling layer 160 is exposed. In particular, the protective layer 510 is formed in the lens array area AA and a portion of the peripheral area PA. The first portion 166 is disposed between the underlying layer 182 and the second part 167. The formation and material of the protective layer 510 may be the same or similar to those of the protective layer 310 of [Fig.3A]. Referring to [Fig.5SA] and [Fig.5B], the second portion 167 of the remaining portion 160a of the filler layer 160 is removed and the upper surface 114 of the substrate 110 is exposed. In other words, the first portion 166 of the remaining portion 160a is held between the protective layer 510 and the substrate 110. In some embodiments, the second portion 167 is removed by a dry etching process. Referring to [Fig.5B] and [Fig.5C], the protective layer 510 is removed so that the lenses 180, the underlying layer 182, and the first portion 166 of the remaining portion 160a are exposed. Referring to [Fig.5C] and [Fig.5D], a photoresist layer 520 is formed on the upper surface 114 of the substrate 110. In particular, the photoresist layer 520 is formed in the peripheral area PA and surrounds the lenses 180, the underlying layer 182, and the first portion 166. The photoresist layer 520 has an obtuse angle between an inclined sidewall 522 of the photoresist layer 520 and the upper surface 114 of the substrate 110. The formation and material of the photoresist layer 520 may be the same or similar to those of the photoresist layer 120 of [Fig.1A]. Referring to [Fig.5D] and [Fig.5E], an antireflection film 530 is formed on upper surfaces 184 of the lenses 180 and an upper surface 162 of the first portion 166 of the remaining portion 160a of the filling layer 160. More particularly, the antireflection film 530 is also formed on an upper surface of the underlying layer 182. The antireflection film 530 has a first portion 530a and a second portion 530b. The first portion 530a is formed on the lenses 180 and the first portion 166, and the second portion 530b is formed on an upper surface 524 of the photosensitive resin layer 520. The formation and material of the anti-reflective film 530 may be the same or similar to those of the anti-reflective film 330 of [Fig.3E]. Referring to [Fig.5E] and [Fig.5F], the photoresist layer 520 and the second portion 530b of the antireflection film 530 are removed from the peripheral area PA. In some embodiments, the removal process is performed by a peeling process. The peeling process of the present disclosure can reduce the stress of the film to avoid stress imbalance and wafer deflection. After forming the lenses with the first portion 530a of the antireflective film 530, performing the steps of FIGS. 1G to 1L or the steps of FIGS. 2A to 2C is continue so that the image sensor 1000C of [Fig.6] is formed. Figures 7A-7E are a succession of cross-sectional views of a method of manufacturing an image sensor 8000A according to certain embodiments of the present disclosure. [Fig. 8] is a cross-sectional view of the image sensor 8000A according to the manufacturing method shown in Figures 7A-7E. As shown in [Fig.7A], the photoresist layer 120 is deposited on the substrate 110. A first portion 710a of an underlying layer 710 is disposed on the upper surface 114 of the substrate 110, and a second portion 710b of the underlying layer 710 is disposed on the upper surface 124 of the photoresist layer 120. A first portion 720a of a lens layer 720 is disposed on the first portion 710a of the underlying layer 710, and a second portion 720b of the lens layer 720 is disposed on the second portion 710b of the underlying layer 710. In other words, in the lens array area AA, before the formation of the lens layer 720 above the substrate 110, the underlying layer 710 is formed on the substrate 110. The underlying layer 710 may be formed by PVD or any other suitable deposition process.In some embodiments, a material of the underlying layer 710 is different from the material of the lens layer 720. In some embodiments, a refractive index (n) and an extinction coefficient (k) of the underlying layer 710 are different from those of the lens layer 720. The formation and material of the lens layer 720 may be the same or similar to those of the lens layer 140 of [Fig. 1B]. As shown in [Fig. 7A] and [Fig. 7B], the photoresist layer 120 is removed. In particular, the second portion 710b of the underlying layer 710 and the second portion 720b of the lens layer 720 are also removed. In some embodiments, the removal process is performed by a peeling process. The peeling process of the present disclosure can reduce the stress of the film to avoid stress imbalance and wafer flexing. As shown in [Fig.7B] and [Fig.7C], a filler layer 730 is formed on the substrate 110 and surrounds the first portion 710a of the underlying layer 710 and the first portion 720a of the lens layer 720. The formation and material of the filler layer 730 may be the same or similar to those of the filler layer 160 of [Fig.1D]. As shown in [Fig.7C] and [Fig.7D], a patterned hard mask layer 740 is formed on the first portion 720a of the lens layer 720 and the filler layer 730. In particular, the patterned hard mask layer 740 has a meta-surface profile on the first portion 720a of the lens layer 720 and the filler layer 730. lens 720 and a planar film profile of the filler layer 730. The formation and material of the patterned hard mask layer 740 may be the same or similar to those of the patterned hard mask layer 170 of [Fig.1E]. As shown in [Fig. 7D] and [Fig. 7E], the lens layer 720 is etched to transfer a pattern of the patterned hard mask layer 740 (including the meta-surface and the planar film) onto the lens layer 720 so that a plurality of lenses 750 are defined. The first portion 710a of the underlying layer 710 may be used as an etch stop layer to protect the substrate 110. In some embodiments, the lenses 750 are meta-surface lenses. The meta-surface lenses 750 are made of several nanostructures (pillars). The lenses 750 are arranged in a meta-surface array (see [Fig. 12]). The lens layer 720 is etched by an etching process E.In particular, in the etching process E, the filler layer 730 is also etched to transfer the pattern of the planar film of the patterned hard mask layer 740 onto the filler layer 730 so that a remaining portion 730a of the filler layer 730 is defined. Since the meta-surface of the lenses 750 is formed by etching the lens layer 720, the material of the meta-surface of the lenses 750 is the same as the material of the lens layer 720, for example, an inorganic material (such as a-Si, SiH, GeH, Ge, GeO, or GeSiH). In such an embodiment, the filler layer 730 and the underlying layer 710 may be used as protective layers to prevent damage to the underlying substrate 110 during the etching process E. After forming the lenses 750 with the meta-surface, performing the steps of FIGS. 1G to 1L or the steps of FIGS. 2A to 2C continues so that the image sensor 8000A of [Fig. 8] is formed. Figures 9-11 are cross-sectional views of image sensors 8000B, 8000C, 8000D according to certain embodiments of the present disclosure. Referring to [Fig. 8] and [Fig. 9], the differences between the image sensor 8000A of [Fig. 8] and the image sensor 8000B of [Fig. 9] are the remaining portion 730a of the filling layer 730. In particular, the image sensor 8000B lacks the remaining portion 730a. Referring to [Fig.8] and [Fig.10]. The differences between the image sensor 8000A of [Fig.8] and the image sensor 8000C of [Fig.10] are the first portion 710a of the underlying layer 710. In particular, the image sensor 8000C lacks the first portion 710a of the underlying layer 710. Refer to [Fig.8] and [Fig.11]. The differences between the image sensor 8000A of [Fig.8] and the image sensor 8000D of [Fig.11] are the first portion 710a of the underlying layer 710 and the remaining portion 730a of the replac- pleating 730. In particular, the 8000D image sensor is devoid of the first portion 710a of the underlying layer 710 and the remaining portion 730a of the filling layer 730. Reference is again made to [Fig. 1L], [Fig. 4], [Fig. 6] and FIGS. 8 to 11. In the image sensors 1000A, 1000B, 1000C of [Fig. 1L], [Fig. 4], [Fig. 6], respectively, a lens 180 corresponds to a photosensitive element 112. In the image sensors 8000A to 8000D of FIGS. 8 to 11, respectively, a lens 750 (including several pillars) corresponds to a photosensitive element 112. Therefore, a lens 180 or a lens 750 can be considered as a pixel size p. [Fig. 12] is a top view of a region A of the image sensor 8000A shown in [Fig. 8]. In particular, a cross-sectional view along a line AA' of [Fig. 12] is the region A of [Fig. 8], [Fig. 12] essentially showing the lenses 750 and the remaining portion 730a of the filler layer 730 and other elements are omitted for clarification. As shown in [Fig. 12], the lenses 750 are arranged in a meta-surface array, the numbers of columns and rows not being limited by the array shown in [Fig. 12]. [Fig. 13A], [Fig. 13B], and [Fig. 13C] are top views of the meta-surface lens 750 of [Fig. 12]. Note that a shape of each pillar in the meta-surface lenses 750 is round in top view. As shown in [Fig. 13A], the pillars are arranged in a square. As shown in [Fig. 13B], the pillars have a hexagonal arrangement. As shown in [Fig. 13C], the pillars have a circular arrangement. Other arrangements of the pillars are also included in this description. The lenses 180 in the aforementioned image sensors 1000A to 1000C are microlenses. The lenses 750 in the aforementioned image sensors 8000A to 8000D are meta-surface lenses. The working wavelength of the image sensors 1000A to 1000C and 8000A to 8000D may be in a range of 780 to 1500 nm, for example 800 to 2500 nm or 1100 to 2000 nm. In some embodiments, the image sensors of the present disclosure are suitable for near infrared light applications. The manufacturing methods of the described image sensors can avoid damage to the substrate under the lens material during the formation of the lens array (which includes the microlens array and the meta-surface lens array), thereby improving the performance of the image sensors. In addition, thicknesses of the described image sensors from the lens array area to the peripheral area are gradually decreased, so that a stress imbalance between a lens array (such as the 180 and 750 lenses) can be avoided. and elements arranged above the lens array and delamination between different materials, thus ensuring good optical performance. The present description has been described as above, however, this is not intended to limit the present description. The person skilled in the art can make numerous modifications, substitutions, and variations without departing from the spirit and scope of the present description. Therefore, the scope of protection of the present description may be subject to the scope of the claim appended in the application and its structural equivalents.
Claims
Claims
1. A method of manufacturing an image sensor, comprising: the provision of a substrate; the formation of a lens layer above the substrate; forming a patterned hard mask layer on the layer of lens: etching the lens layer to transfer a pattern from the layer of patterned hard mask on the lens layer so that a plurality of lenses is defined, in which the lenses are microlenses or meta-surface lenses: forming a coating layer to cover the plurality of lenses and substrate: etching parts of the coating layer to form a first inclined side wall and a second inclined side wall, wherein the first inclined side wall is above the second inclined side wall, in which an extension of the first inclined side wall on the substrate is spaced by a extension of the second inclined side wall onto the substrate; and conformal formation of a bandpass filter layer having a plurality of films on the coating layer and covering the substrate.
2. A method of manufacturing the image sensor according to claim 1, in which, before the formation of the lens layer above the substrate, the method further comprises: the formation of a layer of photosensitive resin with a third inclined side wall having a trench on the substrate; the formation of the lens layer with a fourth side wall inclined in the trench; and the removal of the photosensitive resin layer, in which an angle between the third inclined side wall and an upper surface of the substrate is greater than 90 degrees, and an angle between the fourth wall inclined side and the upper surface of the substrate is less than 90 degrees.
3. A method of manufacturing the image sensor according to claim 2, in which, after the formation of the lens layer above the substrate, the method further comprises: the formation of a filling layer on the substrate and surrounding the lens layer, in which an upper surface of the layer of lens is substantially coplanar with an upper surface of the filling layer; the formation of the patterned hard mask layer on the fill layer pleating; and etching the filling layer to transfer the pattern from the patterned hard mask layer over the filler layer, so that a remaining part of the filling layer and an underlayer underlying are defined, in which the underlying layer is arranged between the plurality of lenses and the substrate, and the underlying layer is connected to the remaining part.
4. A method of manufacturing the image sensor according to claim 3, in which, after defining the remaining part of the filling layer- pleating and the underlying layer, the method further comprises: forming a protective layer to cover the plurality of lenses and expose the remaining part of the filler layer; removal of the remaining part of the filling layer; removal of the protective layer; and the formation of an antireflective film on upper surfaces of the plurality of lenses.
5. A method of manufacturing the image sensor according to claim 3, in which, after defining the remaining part of the filling layer- pleating and the underlying layer, the method further comprises: forming a protective layer to cover the plurality of lenses and a first part of the remaining part of the filling layer pleating, in which a second part of the remaining part of the filler layer is exposed; the removal of the second part of the remaining part of the filling layer pleating; removal of the protective layer; and the formation of an antireflective film on upper surfaces of the plurality of lenses and an upper surface of the first part of the remaining part of the filling layer.
6. A method of manufacturing the image sensor according to claim 1, in which, before the formation of the lens layer above the substrate, an underlying layer is formed on the substrate.
7. A method of manufacturing the image sensor according to claim 1, in which the formation of the coating layer to cover the plurality of lenses and the substrate and etching of the parts of the layer of cladding to form the first inclined side wall and the second inclined side wall, further comprises: the formation of a first coating layer to cover the plurality of lenses and the substrate; etching a portion of the first coating layer to expose part of the substrate and to form a third wall inclined side, in which an angle between the third side wall inclined and an upper surface of the substrate is in a range of from 20 degrees to 60 degrees; the formation of a second coating layer on the first coating layer and the part of the substrate to form the first inclined side wall on a top of the coating layer; and etching a portion of the second coating layer to form the second inclined side wall on a bottom of the layer of cladding, in which an angle between the second side wall inclined and the upper surface of the substrate is in a range from 20 degrees to 60 degrees.
8. A method of manufacturing the image sensor according to claim 1, in which etches parts of the coating layer to form the first inclined wall and the second inclined wall comprises in besides : etching a first part of the coating layer to form the first inclined side wall on a peak of the re- layer garment, in which an angle between the first inclined side wall and an upper surface of the substrate is in a range of 20 degrees to 60 degrees; and etching a second part of the coating layer for form the second inclined side wall on a bottom of the layer of cladding, in which an angle between the second side wall inclined and the upper surface of the substrate is in a range from 20 degrees to 60 degrees.
9. An image sensor, comprising: a substrate; a plurality of lenses disposed on the substrate, wherein the plurality lenses are microlenses or meta-surface lenses; a coating layer disposed on the plurality of lenses and the substrate, wherein the coating layer has a first sidewall inclined and a second inclined side wall, and the first wall inclined side is above the second inclined side wall, wherein an extension of the first inclined side wall on the substrate is separated from an extension of the second side wall inclined on the substrate; and a bandpass filter layer having several films deposited in a manner conformal to the coating layer and covering the substrate.
10. The image sensor of claim 9, further comprising a filling layer and an antireflective film, in which the layer of filler is disposed on the substrate and surrounds the plurality of lenses, a thickness of the filling layer is in a range ranging from 0.1 um to 100 um, and the anti-reflective film is arranged on upper surfaces of the lenses and an upper surface of the layer filling.
11. | An image sensor according to claim 9, further comprising a underlying layer disposed between the plurality of lenses and the substrate, in which a thickness of the underlying layer is within a range ranging from 0.01 um to 100 um.
12. An image sensor according to claim 11, wherein a material of the lenses is an a-Si, SIH, GeH, Ge, GeO or GeSiH, a material of the underlying layer is the same as or different from a material of the lenses, a thickness of the underlying layer is in a range ranging from 0.01 um to 100 um, and a distance between a most external of the second inclined side wall and a most outer layer of the underlying layer is in a range from 40 um to 100 um, wherein, when the plurality of lenses are microlenses, a extension of the microlenses on the substrate is in an extension of the underlying layer on the substrate.
13. An image sensor according to claim 9, wherein an angle between the first inclined side wall and an upper surface of the substrate is in a range from 20 degrees to 60 degrees, in which an angle between the second inclined side wall and the upper surface of the substrate is in a range from 20 degrees to 60 degrees.