Image sensor and method of manufacturing the same

Abstract

An image sensor comprises a semiconductor substrate and a lens array, the semiconductor substrate is provided with a plurality of pixels, each pixel comprises a light sensing unit and a light polarization unit embedded in the light sensing unit at least partially; the lens array is arranged on the semiconductor substrate, and the lens array comprises a plurality of lens units arranged correspondingly to each pixel. The image sensor provided by the application not only has a good noise reduction effect, but also can improve the imaging quality. The application further provides a manufacturing method of the image sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image sensing, in particular to an image sensor and a manufacturing method thereof. BACKGROUND

[0002] An image sensor refers to a device for converting optical signals into electrical signals. Commonly used image sensor chips include charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) image sensor chips. Compared with traditional CCD sensors, CMOS image sensors have the characteristics of low power consumption, low cost and compatibility with CMOS processes, and thus are increasingly widely used. Nowadays, CMOS image sensors are not only used in consumer electronics, such as digital still cameras (DSC), mobile phone cameras, camcorders and digital single-lens reflex (DSLR) cameras, but also widely used in automotive electronics, monitoring, biotechnology and medicine.

[0003] Some CMOS image sensors have a core device including a light sensing device and a light polarizer arranged above the light incident side of the light sensing device. At least one intermediate medium layer is arranged between the light polarizer and the light sensing device, so that the distance between the light polarizer and the light sensing device is large, resulting in large noise and affecting the imaging quality. SUMMARY

[0004] Therefore, the present application provides an image sensor which has good noise reduction effect and improves the imaging quality.

[0005] An image sensor includes a semiconductor substrate and a lens array. The semiconductor substrate is provided with a plurality of pixels, each pixel including a light sensing unit and a light polarization unit at least partially embedded in the light sensing unit. The lens array is arranged on the semiconductor substrate and includes a plurality of lens units arranged corresponding to each pixel.

[0006] In the embodiment of the present application, the incident light enters the light sensing unit from the lens unit via the light polarization unit.

[0007] In the embodiment of the present application, the light polarization unit includes a plurality of wire grids arranged at intervals. Each wire grid includes opposite first and second side edges. The first side edge faces the lens unit, and the second side edge is embedded in the light sensing unit.

[0008] In the embodiment of the present application, the wire grids of the light polarization unit are parallel to each other, and each wire grid of the light polarization unit and each wire grid of the adjacent light polarization unit form an included angle.

[0009] In the embodiment of the present application, the plurality of pixels form a pixel array arranged in rows and columns, and the pixel array comprises a plurality of pixel units, wherein each pixel unit comprises at least two pixels, and the grating of the light polarization unit corresponding to different pixels in the same pixel unit has different inclination angles.

[0010] In the embodiment of the present application, the image sensor further comprises a grid frame embedded at least partially in the semiconductor substrate, and the grid frame is provided with a plurality of light transmission holes corresponding to the pixels, and each light polarization unit is located in each light transmission hole.

[0011] In the embodiment of the present application, the semiconductor substrate is further provided with a plurality of isolation portions for spacing the plurality of light sensing units, and the plurality of isolation portions are arranged corresponding to the grid frame; and / or the grid frame and the grating are made of metal materials, and the grid frame and the grating are made of the same material or different materials.

[0012] In the embodiment of the present application, the light sensing unit comprises a light sensing portion, a transfer transistor, a floating diffusion region, a reset transistor and a source follower transistor, the light sensing portion is used for converting a light signal containing image information into an electrical signal during exposure; the transfer transistor connects the light sensing portion and the floating diffusion region, and is used for transferring the electrical signal of the light sensing portion to the floating diffusion region; the source follower transistor is used for outputting the electrical signal of the floating diffusion region; and the reset transistor is used for resetting the floating diffusion region.

[0013] In the embodiment of the present application, the light sensing unit further comprises a selection transistor, and the selection transistor is used for selecting and outputting the electrical signal output by the source follower transistor to a column line.

[0014] In the embodiment of the present application, the image sensor further comprises an interconnection structure arranged on the side of the semiconductor substrate away from the lens array, and the interconnection structure is provided with an interconnection circuit and a conductive pad electrically connected to each light sensing unit, the conductive pad is electrically connected to the interconnection circuit, and the semiconductor substrate and the interconnection structure are provided with an opening exposing the conductive pad; and / or the image sensor further comprises a color filter arranged between the lens array and the light polarization unit, and the color filter comprises a plurality of color filter units arranged corresponding to the pixels.

[0015] The present application further provides a manufacturing method of the image sensor, and the manufacturing method comprises the following steps:

[0016] A semiconductor substrate is provided, in which a plurality of light sensing units and a plurality of light polarization units are formed, and each of the light polarization units is at least partially embedded in each of the light sensing units;

[0017] A lens array is formed on the side of the semiconductor substrate, and a plurality of lens units of the lens array are respectively arranged corresponding to a plurality of the light sensing units.

[0018] In an embodiment of the present application, the method of the above-mentioned light sensing unit and the light polarization unit comprises:

[0019] The semiconductor substrate comprises opposite first and second surfaces, and a plurality of the light sensing units are formed in the semiconductor substrate from the first surface;

[0020] The second surface of the semiconductor substrate is thinned to form a third surface exposing each of the light sensing units;

[0021] A plurality of first grooves are formed on each of the light sensing units from the third surface, and a metal material is arranged in each of the first grooves to form a wire grid, and a plurality of the wire grids in each of the light sensing units constitute the light polarization unit.

[0022] In an embodiment of the present application, a second groove is formed on the semiconductor substrate from the third surface, and a metal material is arranged in the second groove to form a grid frame, and the grid frame is provided with a plurality of light transmission holes corresponding to each of the light sensing units, and each of the light polarization units is located in each of the light transmission holes.

[0023] In an embodiment of the present application, a plurality of isolation portions are formed in the semiconductor substrate from the first surface and / or the third surface, and a plurality of the isolation portions are arranged corresponding to the grid frame, and a plurality of the isolation portions are used to separate a plurality of the light sensing units from each other.

[0024] In an embodiment of the present application, a plurality of first grooves are formed on each of the light sensing units from the third surface at the same time, and a second groove is formed on the semiconductor substrate;

[0025] A metal material is arranged in each of the first grooves to form a wire grid, and a plurality of the wire grids in each of the light sensing units constitute the light polarization unit; a metal material is arranged in the second groove to form a grid frame, and the grid frame is provided with a plurality of light transmission holes corresponding to each of the light sensing units, and each of the light polarization units is located in each of the light transmission holes.

[0026] In an embodiment of the present application, the manufacturing method further comprises:

[0027] After forming the light-sensing units, an interconnection structure is prepared on the semiconductor substrate, the interconnection structure is arranged on the side of the semiconductor substrate away from the lens array, and the interconnection structure is provided with an interconnection circuit and a conductive pad electrically connected to each of the light-sensing units;

[0028] An opening exposing the conductive pad is formed in the semiconductor substrate and the interconnection structure.

[0029] In the embodiment of the present application, the manufacturing method further comprises:

[0030] After forming the light polarization units, a color filter is prepared on the light polarization units, the color filter is arranged between the lens array and the light polarization units, and the color filter comprises a plurality of color filter units arranged corresponding to each of the pixels.

[0031] The light polarization units of the image sensor of the present application are at least partially embedded in the light-sensing units, and the light polarization units are arranged at a negative distance from the light-sensing units, which not only has a good noise reduction effect but also improves the imaging quality. Due to the negative distance arrangement of the light polarization units and the light-sensing units, the size of the image sensor can be reduced, and thinning can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1a is a partial cross-sectional schematic view of the image sensor of the present application.

[0033] Figure 1b is Figure 1a is a partial enlarged schematic view of the image sensor shown in FIG. 1.

[0034] Figure 2 is a top view structural schematic view of a pixel unit of the present application.

[0035] Figure 3 is a pixel circuit structural schematic view of the image processor of the present application.

[0036] Figures 4 to 12 is a flowchart schematic view of the manufacturing method of the image sensor of the present application. DETAILED DESCRIPTION

[0037] The embodiments of the present application are described below by specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the present specification.

[0038] In the following description, reference is made to the accompanying drawings, which illustrate several embodiments of the present application. It is understood that other embodiments can be used and that mechanical, structural, electrical, and operational changes can be made without departing from the spirit and scope of the present application. The following detailed description is not intended to be limiting, and the terms used herein are merely used to describe specific embodiments, and are not intended to limit the present application.

[0039] Although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0040] Furthermore, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including" when used herein, specify the presence of stated features, steps, operations, elements, components, items, and / or groups but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, items, and / or groups thereof. As used herein, the terms "or" and "and / or" are to be interpreted as inclusive, i.e., as meaning one or any combination of items. Thus, "A, B or C" or "A, B and / or C" means any of the following: A; B; C; A and B; A and C; B and C; A, B and C. An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.

[0041] Figure 1a is a schematic view of a partial section of an image sensor of the present application, Figure 1b is Figure 1a is a schematic view of a partial enlargement of the image sensor shown in Figure 1a and Figure 1b As shown in Figs. 1 and 2, the image sensor comprises a semiconductor substrate 11 and a lens array 12, the semiconductor substrate 11 being provided with a plurality of pixels, each pixel comprising a light sensing unit 112 and a light polarization unit 113 at least partially embedded in the light sensing unit 112, and the lens array 12 being arranged on the semiconductor substrate 11, the lens array 12 comprising a plurality of lens units 121 arranged in correspondence with each pixel.

[0042] The light polarization unit 113 of the image sensor of the present application is at least partially embedded in the light sensing unit 112, and the light polarization unit 113 is arranged in negative distance with the light sensing unit 112, which not only has a good noise reduction effect, but also can improve the imaging quality. Due to the negative distance arrangement of the light polarization unit 113 and the light sensing unit 112, the size of the image sensor can be reduced, and thinning can be realized.

[0043] Optionally, the semiconductor substrate 11 is a silicon material doped with p-type dopants such as boron, or a silicon doped with n-type dopants such as phosphorus or arsenic, or other elemental semiconductors such as germanium or diamond.

[0044] Optionally, the incident light enters the light sensing unit 112 from the lens unit 121 via the light polarization unit 113, i.e. the image sensor of the present embodiment is a back-illuminated polarization CMOS image sensor.

[0045] Optionally, the light polarization unit 113 comprises a plurality of wire grids 1131 arranged at intervals, each wire grid 1131 comprises opposite first and second side edges 1132 and 1133, the first side edge 1132 faces the lens unit 121, and the second side edge 1133 is embedded in the photosensitive unit 112. In this embodiment, the wire grids 1131 of the light polarization unit 113 are formed by wet etching or dry etching; for example, a plurality of first grooves 101 are formed on the surface of each photosensitive unit 112 (for example, the first grooves 101 are formed by etching), then a layer of metal material is formed on the surface of the semiconductor substrate 11 and the photosensitive unit 112 (the layer of metal material can be formed by using a sputtering process, an electroplating process, an evaporation process, a chemical vapor deposition (CVD) process, an atomic layer deposition (ALD) process, or any suitable deposition method), and the metal material fills the first grooves 101, and finally a chemical mechanical polishing (CMP) or etching process is used to remove the metal material outside the first grooves 101, and the metal material in the first grooves 101 is retained to form the wire grids 1131.

[0046] Optionally, the height of each wire grid 1131 from the first side edge 1132 to the second side edge 1133 is 200 nm to 1000 nm, for example, it can be 500 nm, 600 nm, or 800 nm.

[0047] Optionally, the plurality of wire grids 1131 of the light polarization unit 113 are parallel to each other, and each wire grid 1131 of the light polarization unit 113 forms an included angle with each wire grid 1131 of the adjacent light polarization unit 113.

[0048] Optionally, Figure 2 is a top view structural schematic diagram of a pixel unit of the present application, as Figure 2 shown, a plurality of pixels form a pixel array arranged in rows and columns, the pixel array comprises a plurality of pixel units, wherein each pixel unit comprises at least two pixels, and the wire grids 1131 of the light polarization units 113 corresponding to different pixels in the same pixel unit have different inclination angles. In this embodiment, the pixel unit comprises four pixels arranged in a matrix; the wire grids 1131 in the upper left pixel are arranged in a vertical direction, the wire grids 1131 in the upper right pixel are arranged obliquely, and the wire grids 1131 in the upper left pixel and the wire grids 1131 in the upper right pixel form an included angle of 45°; the wire grids 1131 in the lower left pixel are arranged obliquely, the oblique direction of the wire grids 1131 in the lower left pixel is opposite to the oblique direction of the wire grids 1131 in the upper right pixel, the wire grids 1131 in the lower right pixel are arranged in a horizontal direction, and the wire grids 1131 in the lower left pixel and the wire grids 1131 in the lower right pixel form an included angle of 135°, that is, each light polarization unit 113 in each pixel unit can provide polarization information of incident light along the following polarization angles: 0°, 45°, 90°, and 135°.

[0049] It is worth mentioning that the number of pixels in each pixel unit and the angle between the two adjacent wire grids 1131 of the light polarization unit 113 can be designed according to actual needs, and is not limited to the above.

[0050] Optionally, the distance between the two adjacent wire grids 1131 can be in the range from 100 nanometers (nm) to 500 nm (for example, from 100 nm to 500 nm), for example, can be selected as 200 nm, 300 nm; the width of each wire grid 1131 can be in the range from 20 nm to 300 nm (for example, from 20 nm to 300 nm), for example, can be selected as 50 nm, 100 nm. Based on the wavelength of the incident light, the above range is preferred.

[0051] Optionally, the image sensor further comprises a grid frame 13, the grid frame 13 is at least partially embedded in the semiconductor substrate 11, the grid frame 13 is provided with a plurality of light transmission holes 104 corresponding to each pixel, and each light polarization unit 113 is located in each light transmission hole 104. In this embodiment, the grid frame 13 is formed by wet etching or dry etching; for example, a second groove 102 is made on the surface of each semiconductor substrate 11 (for example, the second groove 102 is made by etching), then a metal material is formed on the surface of the semiconductor substrate 11 and the light sensing unit 112 (the metal material layer can be formed by using sputtering process, electroplating process, evaporation process, chemical vapor deposition (CVD) process, atomic layer deposition (ALD) process or any suitable deposition method), and the metal material fills the second groove 102, and finally the metal material outside the second groove 102 is removed by using chemical mechanical grinding (CMP) or etching process, that is, the metal material covering the light sensing unit 112 is removed, the material in the second groove 102 is retained to form the grid frame 13, and the etched removed area forms the light transmission hole 104.

[0052] In this embodiment, the first groove 101 and the second groove 102 are formed at the same time based on the same process step, so as to ensure the self-alignment position of the wire grid 1131 and the grid frame 13, which is beneficial to improve the stability and preparation precision of the device, and is beneficial to improve the anti-light crosstalk performance of the device and improve the image quality. Further optionally, the wire grid 1131 and the grid frame 13 can be prepared and formed in the same process based on the first groove 101 and the second groove 102, which can simplify the overall preparation process of the device. In other embodiments, the grid frame 13 can be made first, and then the wire grid 1131 can be made; or the grid frame 13 and the wire grid 1131 can be made at the same time. Optionally, the height of the grid frame 13 is greater than or equal to the height of the wire grid 1131.

[0053] Optionally, the semiconductor substrate 11 further comprises isolation portions 114 for separating the plurality of light sensing units 112 from each other, and the plurality of isolation portions 114 are arranged corresponding to the grid frame 13. In the embodiment, the top of the isolation portion 114 is flush with the surface of the semiconductor substrate 11, the lower surface of the grid frame 13 extends into the isolation portion 114, and the bottom of the isolation portion 114 extends to the lower surface of the semiconductor substrate 11; the isolation portion 114 is arranged directly opposite to the grid frame 13, and the orthographic projection of the grid frame 13 at least partially covers the isolation portion 114.

[0054] Optionally, the isolation portion 114 can be a groove etched on the upper surface and / or the lower surface of the semiconductor substrate 11 and filled with a dielectric material, such as silicon oxide, silicon nitride, silicon oxynitride, fluorine-doped silicate glass (FSG), low-k dielectric material (e.g., material with k value less than 3.9), and / or suitable insulating material. The isolation portion 114 can comprise a front-side shallow trench isolation structure (STI) and a back-side deep trench isolation structure (BDTI) arranged correspondingly, and in other embodiments, the isolation portion 114 can also be an ion implantation isolation region formed on the front side (e.g., for an N-type doped light sensing unit, a P-type doped isolation structure is arranged).

[0055] Optionally, the grid frame 13 and the wire grid 1131 are both made of metal material, and the grid frame 13 and the wire grid 1131 can be made of the same material or different materials. For example, the grid frame 13 is made of tungsten, aluminum or copper; and the wire grid 1131 is made of tungsten, aluminum or copper. Of course, in other embodiments, the grid frame 13 and the wire grid 1131 can also be made of different materials.

[0056] Optionally, Figure 3 is a schematic diagram of a pixel circuit structure of an image processor of the present application, as Figure 3 shown, the light sensing unit 112 comprises a light sensing portion PD, a transfer transistor TX, a floating diffusion region FD, a reset transistor RST, and a source follower transistor SF; the light sensing portion PD is used for converting a light signal containing image information into an electrical signal during exposure; the transfer transistor TX connects the light sensing portion PD and the floating diffusion region FD, and is used for transferring the electrical signal of the light sensing portion PD to the floating diffusion region FD; the source follower transistor SF is used for outputting the electrical signal of the floating diffusion region FD; and the reset transistor RST is used for resetting the floating diffusion region FD. The semiconductor substrate 11 is doped, for example, by ion implantation, so as to form the light sensing portion PD, the floating diffusion region FD, and the source and drain of the transfer transistor TX, the source follower transistor SF, the reset transistor RST, and the selection transistor RS in the semiconductor substrate 11.

[0057] Optionally, the photosensitive unit 112 further comprises a selection transistor RS, which is configured to select and output the electrical signal output by the source follower transistor SF to a column line (Pixel out).

[0058] Optionally, the image sensor further comprises an interconnection structure 14, which is arranged on the side of the semiconductor substrate 11 away from the lens array 12, and the interconnection structure 14 is provided with an interconnection circuit 141 and a conductive disc 142 electrically connected to each photosensitive unit 112, the conductive disc 142 is electrically connected to the interconnection circuit 141, and the semiconductor substrate 11 and the interconnection structure 14 are provided with an opening 103 exposing the conductive disc 142. In this embodiment, the interconnection structure 14 can undergo multiple photolithography, etching, deposition and planarization operations. Of course, the position of the interconnection structure 14 can also be arranged according to actual needs, such as the image sensor of the FSI structure.

[0059] Optionally, the materials of the interconnection circuit 141 and the conductive disc 142 are titanium, tungsten, aluminum or copper, but are not limited thereto.

[0060] Optionally, the image sensor further comprises a color filter 15, which is arranged between the lens array 12 and the light polarization unit 113, and the color filter 15 comprises a plurality of color filter units 151 arranged corresponding to each pixel. In this embodiment, each color filter unit 151 of the color filter 15 can be an R color filter unit for filtering red light, a G color filter unit for filtering green light, a B color filter unit for filtering blue light, or a color filter unit for filtering white light.

[0061] It is worth mentioning that the color filter 15 can not be arranged between the lens array 12 and the light polarization unit 113.

[0062] Figures 4 to 12 is a flowchart of the manufacturing method of the image sensor of the present application, please refer to Figures 4 to 12 The present application further provides a manufacturing method of the image sensor as described above, the manufacturing method comprises:

[0063] providing a semiconductor substrate 11, manufacturing a plurality of photosensitive units 112 and a plurality of light polarization units 113 in the semiconductor substrate 11, and embedding each light polarization unit 113 at least partially in each photosensitive unit 112;

[0064] manufacturing a lens array 12 on one side of the semiconductor substrate 11, and arranging a plurality of lens units 121 of the lens array 12 corresponding to a plurality of photosensitive units 112 respectively.

[0065] The manufacturing method of the image sensor of the present application can embed the light polarization unit 113 at least partially into the light sensing unit 112, and the light polarization unit 113 is arranged in negative distance with the light sensing unit 112, which not only has good noise reduction effect, but also can improve the imaging quality. Due to the negative distance arrangement of the light polarization unit 113 and the light sensing unit 112, the size of the image sensor can be reduced, and thinning can be realized.

[0066] Optionally, the method of the light sensing unit 112 and the light polarization unit 113 comprises:

[0067] The semiconductor substrate 11 comprises opposite first face 1111 and second face 1112, and a plurality of light sensing units 112 are formed in the semiconductor substrate 11 from the first face 1111;

[0068] The second face 1112 of the semiconductor substrate 11 is subjected to thinning treatment to form a third face 1113 exposing each light sensing unit 112;

[0069] A plurality of first grooves 101 are formed on each light sensing unit 112 from the third face 1113, and a wire grid 1131 is arranged in each first groove 101 by using metal material, and a plurality of wire grids 1131 in each light sensing unit 112 constitute a light polarization unit 113. In the present embodiment, the semiconductor substrate 11 can be subjected to thinning treatment by using mechanical grinding and polishing to expose the light sensing unit 112.

[0070] Optionally, a second groove 102 is formed on the semiconductor substrate 11 from the third face 1113, and a grid frame 13 is arranged in the second groove 102 by using metal material, and the grid frame 13 is provided with a plurality of light transmission holes 104 arranged corresponding to each light sensing unit 112, and each light polarization unit 113 is located in each light transmission hole 104.

[0071] Optionally, the grid frame 13 can be manufactured first, and then the wire grid 1131 can be manufactured; or the grid frame 13 and the wire grid 1131 can be manufactured simultaneously, for example, a plurality of first grooves 101 are formed on each light sensing unit 112 from the third face 1113 at the same time, and a second groove 102 is formed on the semiconductor substrate 11 at the same time, for example, the first groove 101 and the second groove 102 are manufactured at the same time by etching;

[0072] Then, a metal material layer is formed on the third surface 1113 by using a sputtering process, an electroplating process, an evaporation process, a chemical vapor deposition (CVD) process, an atomic layer deposition (ALD) process, or any suitable deposition method, and finally, the metal material outside the first grooves 101 and the second grooves 102 is etched to remove, so as to form the wire grids 1131 in each first groove 101 and form the grid frames 13 in each second groove 102, wherein the plurality of wire grids 1131 in each photosensitive unit 112 constitute a light polarization unit 113, and the grid frames 13 form a plurality of light passing holes 104 corresponding to each photosensitive unit 112, and each light polarization unit 113 is located in each light passing hole 104.

[0073] Optionally, a plurality of isolation portions 114 are formed in the semiconductor substrate 11 from the first surface 1111 and / or the third surface 1113, the plurality of isolation portions 114 are arranged corresponding to the grid frames 13, and the plurality of isolation portions 114 are used to separate the plurality of photosensitive units 112 from each other.

[0074] Optionally, the manufacturing method further comprises:

[0075] After the photosensitive unit 112 is formed, an interconnection structure 14 is prepared on the semiconductor substrate 11, the interconnection structure 14 is arranged on the side of the semiconductor substrate 11 away from the lens array 12, and the interconnection structure 14 is provided with an interconnection circuit 141 and a conductive pad 142 electrically connected to each photosensitive unit 112.

[0076] An opening 103 exposing the conductive pad 142 is formed in the semiconductor substrate 11 and the interconnection structure 14.

[0077] Optionally, the manufacturing method further comprises:

[0078] After the light polarization unit 113 is formed, a color filter 15 is prepared on the light polarization unit 113, the color filter 15 is arranged between the lens array 12 and the light polarization unit 113, and the color filter 15 comprises a plurality of color filter units 151 arranged corresponding to each pixel.

[0079] Please refer to Figures 4 to 12 The flow of the manufacturing method of the image sensor of the present application comprises:

[0080] Step one, providing a first support substrate 21, and arranging a semiconductor substrate 11 on the first support substrate 21, as shown in Figure 4 In this example, the first support substrate 21 can be considered as a silicon wafer substrate, and the semiconductor substrate 11 is a P-type epitaxial layer (P-Epi) formed on the silicon wafer substrate. Of course, in other embodiments, the first support substrate 21 and the semiconductor substrate 11 can also be an integrated material layer, such as a Si substrate, and of course, other types of substrate structures for preparing image sensors can also be used.

[0081] Step two, as shown in the figure, a plurality of photosensitive units 112 and a plurality of isolation portions 114 are formed in the semiconductor substrate 11 from the first surface 1111. The plurality of isolation portions 114 are used to space the plurality of photosensitive units 112 apart from each other, such as... Figure 5 As shown.

[0082] Step 3: An interconnect structure 14 is fabricated on the first surface 1111 of the semiconductor substrate 11. The interconnect structure 14 contains interconnect circuits 141 and conductive pads 142 that are electrically connected to each photosensitive unit 112, such as... Figure 6 As shown.

[0083] Step four: A second support substrate 22 is disposed on the side of the interconnect structure 14 away from the semiconductor substrate 11. After flipping the semiconductor substrate 11, the interconnect structure 14, and the first support substrate 21, the structure formed in the above steps is then flipped again, and the second surface 1112 of the semiconductor substrate 11 is thinned to form a third surface 1113 exposing each photosensitive unit 112, as shown. Figure 7 As shown.

[0084] Step 5: Simultaneously, from the third surface 1113, a plurality of mutually spaced first grooves 101 are formed on each photosensitive unit 112, and a second groove 102 is formed on the semiconductor substrate 11, as follows: Figure 8 As shown. In this embodiment, the first groove 101 and the second groove 102 are formed simultaneously based on the same process step, which can ensure the self-alignment position of the wire grid 1131 and the grid frame 13, which is beneficial to improving the stability and fabrication accuracy of the device, improving the anti-optical crosstalk performance of the device, and improving image quality.

[0085] Step six: A metal material layer is formed on the third surface 1113. The metal material outside the first groove 101 and the second groove 102 is removed. A wire grid 1131 is formed in each of the first grooves 101, and a grid frame 13 is formed in each of the second grooves 102. Multiple wire grids 1131 in each photosensitive unit 112 constitute a light polarization unit 113. The grid frame 13 forms multiple light-transmitting holes 104 corresponding to each photosensitive unit 112. Each light polarization unit 113 is located in each light-transmitting hole 104, such as... Figure 9 As shown. In other embodiments, the second groove 102 can be fabricated first, and a grid frame 13 can be formed in the second groove 102, followed by the fabrication of the first groove 101, and then the wire grid 1131 can be formed in the first groove 101. Of course, it can also be done according to the actual design.

[0086] Step 7: Create an opening 103 in the semiconductor substrate 11 and interconnect structure 14 to expose the conductive pad 142, such as... Figure 10 As shown. In this embodiment, the opening 103 can be formed simultaneously with the first groove 101 and the second groove 102 in step five, and can be freely selected according to actual needs.

[0087] Step eight, color filters 15 are prepared on the light polarization unit 113, and the multiple color filter units 151 of the color filters 15 are arranged corresponding to the multiple pixels, as shown in Figure 11 .

[0088] Step nine, lens arrays 12 are prepared on the color filters 15, and the multiple lens units 121 of the lens arrays 12 are arranged corresponding to the multiple light sensing units 112 respectively, as shown in Figure 12 .

[0089] The above embodiments are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed by the present application should be covered by the claims of the present application.

Claims

1. An image sensor, characterized by, The image sensor comprises: a semiconductor substrate provided with a plurality of pixels, each of the pixels comprising a light sensing unit and a light polarization unit embedded at least partially in the light sensing unit; a lens array arranged on the semiconductor substrate, the lens array comprising a plurality of lens units arranged correspondingly to each of the pixels.

2. The image sensor of claim 1, wherein, The incident light enters the light sensing unit from the lens unit via the light polarization unit.

3. The image sensor of claim 1, wherein, The light polarization unit comprises a plurality of wire grids arranged at intervals, each of the wire grids comprising opposite first and second side edges, the first side edge being directed towards the lens unit, and the second side edge being embedded in the light sensing unit.

4. The image sensor of claim 3, wherein, The wire grids of the light polarization unit are parallel to each other, and each of the wire grids of the light polarization unit forms an angle with each of the wire grids of the adjacent light polarization unit.

5. The image sensor of claim 4, wherein, The plurality of pixels form a pixel array arranged in rows and columns, the pixel array comprising a plurality of pixel units, each of the pixel units comprising at least two of the pixels, and the wire grids of the light polarization units corresponding to different pixels in the same pixel unit have different angles of inclination.

6. The image sensor of claim 3, wherein, The image sensor further comprises a grid frame embedded at least partially in the semiconductor substrate, the grid frame being provided with a plurality of light transmission holes arranged correspondingly to each of the pixels, and each of the light polarization units is located in each of the light transmission holes.

7. The image sensor of claim 6, wherein, The semiconductor substrate is further provided with a plurality of isolation portions for spacing the light sensing units at intervals, and the grid frame and the wire grids are made of metal materials, and the grid frame and the wire grids are made of the same material or different materials.

8. The image sensor of claim 1, wherein, The light sensing unit comprises a light sensing portion, a transfer transistor, a floating diffusion region, a reset transistor and a source follower transistor, the light sensing portion being used for converting a light signal containing image information into an electrical signal during exposure; the transfer transistor is connected to the light sensing portion and the floating diffusion region, and is used for transferring the electrical signal of the light sensing portion to the floating diffusion region; the source follower transistor is used for outputting the electrical signal of the floating diffusion region; and the reset transistor is used for resetting the floating diffusion region.

9. The image sensor of claim 8, wherein, The light sensing unit further comprises a selection transistor, which is used for selecting and outputting the electrical signal output by the source follower transistor to a column line.

10. The image sensor according to any one of claims 1 to 9, wherein The image sensor further comprises an interconnection structure arranged on a side of the semiconductor substrate away from the lens array, the interconnection structure being provided with an interconnection circuit and a conductive pad electrically connected to each of the light sensing units, the conductive pad being electrically connected to the interconnection circuit, and the semiconductor substrate and the interconnection structure are provided with an opening exposing the conductive pad; and / or The image sensor further comprises a color filter arranged between the lens array and the light polarization unit, the color filter comprising a plurality of color filter units arranged correspondingly to each of the pixels.

11. A method of manufacturing an image sensor as claimed in any one of claims 1 to 10, characterized in that The manufacturing method comprises: A semiconductor substrate is provided, in which a plurality of light sensing units and a plurality of light polarization units are formed, and each of the light polarization units is at least partially embedded in each of the light sensing units; A lens array is formed on one side of the semiconductor substrate, and a plurality of lens units of the lens array are respectively arranged corresponding to a plurality of the light sensing units.

12. The method of fabricating an image sensor according to claim 11, wherein The method for forming the light sensing units and the light polarization units comprises: The semiconductor substrate comprises opposite first and second surfaces, and a plurality of the light sensing units are formed in the semiconductor substrate from the first surface; The second surface of the semiconductor substrate is thinned to form a third surface exposing each of the light sensing units; A plurality of first grooves are formed on each of the light sensing units from the third surface, and a plurality of wire grids are arranged in each of the first grooves by using metal material, and a plurality of the wire grids in each of the light sensing units form the light polarization unit.

13. The method of fabricating an image sensor according to claim 12, wherein A second groove is formed on the semiconductor substrate from the third surface, and a grid frame is arranged in the second groove by using metal material, the grid frame is provided with a plurality of light transmission holes arranged corresponding to each of the light sensing units, and each of the light polarization units is located in each of the light transmission holes.

14. The method of fabricating an image sensor according to claim 13, wherein, A plurality of isolation portions are formed in the semiconductor substrate from the first surface and / or the third surface, a plurality of the isolation portions are arranged corresponding to the grid frame, and a plurality of the isolation portions are used to separate a plurality of the light sensing units from each other.

15. The method of fabricating an image sensor of claim 13, wherein, A plurality of first grooves are formed on each of the light sensing units from the third surface, and a second groove is formed on the semiconductor substrate from the third surface; A plurality of wire grids are arranged in each of the first grooves by using metal material, and a plurality of the wire grids in each of the light sensing units form the light polarization unit; a grid frame is arranged in the second groove by using metal material, the grid frame is provided with a plurality of light transmission holes arranged corresponding to each of the light sensing units, and each of the light polarization units is located in each of the light transmission holes.

16. The method of fabricating an image sensor according to any one of claims 11 to 15, wherein The forming method further comprises: After forming the light sensing units, an interconnection structure is prepared on the semiconductor substrate, the interconnection structure is arranged on a side of the semiconductor substrate away from the lens array, and the interconnection structure is provided with an interconnection circuit and a conductive pad electrically connected to each of the light sensing units; An opening exposing the conductive pad is formed in the semiconductor substrate and the interconnection structure.

17. The method of fabricating an image sensor according to any one of claims 11 to 15, wherein The forming method further comprises: After forming the light polarization units, a color filter is prepared on the light polarization units, the color filter is arranged between the lens array and the light polarization units, and the color filter comprises a plurality of color filter units arranged corresponding to each of the pixels.

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