CN117080227A - Image sensor and method for manufacturing the same - Google Patents
Image sensor and method for manufacturing the same Download PDFInfo
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14625—Optical elements or arrangements associated with the device
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
- H01L27/1461—Pixel-elements with integrated switching, control, storage or amplification elements characterised by the photosensitive area
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/1462—Coatings
- H01L27/14621—Colour filter arrangements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
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- H01L27/14625—Optical elements or arrangements associated with the device
- H01L27/14627—Microlenses
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
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- H01L27/1463—Pixel isolation structures
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
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- H01L27/14601—Structural or functional details thereof
- H01L27/14636—Interconnect structures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
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- Microelectronics & Electronic Packaging (AREA)
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Abstract
An image sensor includes a semiconductor substrate provided with a plurality of pixels, each pixel including a photosensitive unit and a light polarizing unit at least partially embedded in the photosensitive unit, and a lens array; the lens array is disposed on the semiconductor substrate, and the lens array includes a plurality of lens units disposed corresponding to the pixels. The image sensor provided by the application has a good noise reduction effect and can improve imaging quality. The application also provides a manufacturing method of the image sensor.
Description
Technical Field
The present application relates to the field of image sensing technologies, and in particular, to an image sensor and a method for manufacturing the same.
Background
Image sensors refer to devices that convert optical signals into electrical signals, and typically large-scale commercial image sensor chips include two broad categories, charge Coupled Devices (CCDs) and Complementary Metal Oxide Semiconductor (CMOS) image sensor chips. Compared with the traditional CCD sensor, the CMOS image sensor has the characteristics of low power consumption, low cost, compatibility with the CMOS process and the like, and therefore, the CMOS image sensor is more widely applied. CMOS image sensors are now used not only in consumer electronics, such as miniature digital cameras (DSC), cell phone cameras, video cameras and digital single contrast (DSLR), but also in automotive electronics, monitoring, biotechnology and medicine.
The core device of some CMOS image sensors comprises a photosensitive device and a light polarizer arranged above the light incident side of the photosensitive device, wherein at least one middle dielectric layer is arranged between the light polarizer and the photosensitive device, so that the distance between the light polarizer and the photosensitive device is larger, the noise is large, and the imaging quality is influenced.
Disclosure of Invention
In view of this, the present application provides an image sensor, which has good noise reduction effect and can improve imaging quality.
An image sensor includes a semiconductor substrate provided with a plurality of pixels, each pixel including a photosensitive unit and a light polarizing unit at least partially embedded in the photosensitive unit, and a lens array; the lens array is disposed on the semiconductor substrate, and the lens array includes a plurality of lens units disposed corresponding to the pixels.
In an embodiment of the application, incident light enters the light sensing unit from the lens unit via the light polarizing unit.
In an embodiment of the present application, the light polarization unit includes a plurality of grids disposed at intervals, each of the grids includes a first side and a second side opposite to each other, the first side faces the lens unit, and the second side is embedded in the photosensitive unit.
In an embodiment of the present application, a plurality of the wire grids of the light polarization units 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 with each other.
In an embodiment of the present application, the plurality of pixels form a pixel array arranged in rows and columns, and the pixel array includes a plurality of pixel units, where each pixel unit includes at least two pixels, and inclination angles of the wire grids of the light polarization units corresponding to different pixels in the same pixel unit are different.
In an embodiment of the present application, the image sensor further includes a grid frame at least partially embedded in the semiconductor substrate, where the grid frame is provided with a plurality of light holes corresponding to the pixels, and each of the light polarization units is located in each of the light holes.
In an embodiment of the present application, a plurality of isolation portions for spacing the photosensitive units from each other are further disposed in the semiconductor substrate, and the plurality of isolation portions are disposed corresponding to the grid frame; and/or the grating frame and the grating are made of metal materials, wherein the material of the grating frame is the same as that of the grating, or the material of the grating frame is different from that of the grating.
In an embodiment of the present application, the above-described photosensitive unit includes a photosensitive portion for converting an optical signal containing image information into an electrical signal during exposure, a transfer transistor, a floating diffusion region, a reset transistor, and a source follower transistor; the transmission transistor is connected with the photosensitive part and the floating diffusion region and is used for transferring the electric signal of the photosensitive part to the floating diffusion region; the source follower transistor is used for outputting an electric signal of the floating diffusion region; the reset transistor is used for resetting the floating diffusion region.
In an embodiment of the present application, the above-mentioned photosensitive unit further includes a selection transistor for selectively outputting the electric signal output from the source follower transistor to a column line.
In an embodiment of the present application, the image sensor further includes an interconnection structure, where the interconnection structure is disposed on a side of the semiconductor substrate away from the lens array, and an interconnection circuit and a conductive pad electrically connected to each of the photosensitive cells are disposed in the interconnection structure, and the conductive pad is electrically connected to the interconnection circuit, and openings exposing the conductive pad are disposed in the semiconductor substrate and the interconnection structure; and/or the image sensor further comprises a color filter, wherein the color filter is arranged between the lens array and the light polarization unit, and the color filter comprises a plurality of color filtering units which are arranged corresponding to the pixels.
The application also provides a manufacturing method of the image sensor, which comprises the following steps:
providing a semiconductor substrate, manufacturing a plurality of photosensitive units and a plurality of light polarization units in the semiconductor substrate, and enabling each light polarization unit to be at least partially embedded into each photosensitive unit;
and manufacturing a lens array on one side of the semiconductor substrate, and arranging a plurality of lens units of the lens array corresponding to the plurality of photosensitive units respectively.
In an embodiment of the present application, the method for the photosensitive unit and the light polarization unit includes:
the semiconductor substrate comprises a first surface and a second surface which are opposite, and a plurality of photosensitive units are formed in the semiconductor substrate from the first surface;
thinning the second surface of the semiconductor substrate to form a third surface exposing each photosensitive unit;
and forming a plurality of first grooves which are spaced from each other on each photosensitive unit from the third surface, forming wire grids by arranging metal materials in the first grooves, and forming the light polarization units by the wire grids in the photosensitive units.
In an embodiment of the present application, a second groove is formed on the semiconductor substrate from the third surface, a metal material is disposed in the second groove to form a grid frame, and the grid frame is provided with a plurality of light through holes corresponding to the photosensitive units, and each light polarization unit is located in each light through hole.
In an embodiment of the present application, a plurality of spacers are formed in the semiconductor substrate from the first surface and/or the third surface, the plurality of spacers being disposed corresponding to the grid frame, the plurality of spacers being configured to space the plurality of photosensitive cells from each other.
In an embodiment of the present application, a plurality of first grooves spaced apart from each other are formed on each of the photosensitive cells from the third surface at the same time, and a second groove is formed on the semiconductor substrate;
providing a metal material in each first groove to form a wire grid, wherein a plurality of wire grids in each photosensitive unit form the light polarization unit; and a metal material is arranged in the second groove to form a grid frame, the grid frame is provided with a plurality of light through holes which are arranged corresponding to the photosensitive units, and the light polarization units are positioned in the light through holes.
In an embodiment of the present application, the above manufacturing method further includes:
after the photosensitive units are formed, preparing an interconnection structure on the semiconductor substrate, wherein the interconnection structure is arranged on one side of the semiconductor substrate, which is far away from the lens array, and an interconnection circuit and a conductive disc which are electrically connected with each photosensitive unit are arranged in the interconnection structure;
openings are made in the semiconductor substrate and the interconnect structure exposing the conductive pads.
In an embodiment of the present application, the above manufacturing method further includes:
after the light polarization unit is formed, a color filter is prepared on the light polarization unit, the color filter is arranged between the lens array and the light polarization unit, and the color filter comprises a plurality of color filtering units which are arranged corresponding to the pixels.
The light polarization unit of the image sensor is at least partially embedded into the photosensitive unit, and the light polarization unit and the photosensitive unit are arranged at a negative distance, so that the noise reduction effect is good, and the imaging quality can be improved. Due to the negative distance between the light polarization unit and the photosensitive unit, the size of the image sensor can be reduced, and the light and thin structure can be realized.
Drawings
Fig. 1a is a schematic partial cross-sectional view of an image sensor of the present application.
Fig. 1b is an enlarged partial schematic view of the image sensor shown in fig. 1 a.
Fig. 2 is a schematic top view of a pixel unit according to the present application.
Fig. 3 is a schematic diagram of a pixel circuit structure of an image processor according to the present application.
Fig. 4 to 12 are schematic flow diagrams of a method for manufacturing an image sensor according to the present application.
Detailed Description
Further advantages and effects of the present application will become apparent to those skilled in the art from the disclosure of the present application, which is described by the following specific examples.
In the following description, reference is made to the accompanying drawings which describe several embodiments of the application. It is to be understood that other embodiments may be utilized and that mechanical, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present application. The following detailed description is not to be taken in a limiting sense, and the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
Although the terms first, second, etc. may be used herein to describe various elements in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.
Furthermore, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including" specify the presence of stated features, steps, operations, elements, components, items, categories, and/or groups, but do not preclude the presence, presence or addition of one or more other features, steps, operations, elements, components, items, categories, and/or groups. The terms "or" and/or "as used herein are to be construed as inclusive, or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a, A is as follows; b, a step of preparing a composite material; c, performing operation; 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 operations are in some way inherently mutually exclusive.
Fig. 1a is a schematic view of a partial cross section of an image sensor of the present application, fig. 1b is an enlarged schematic view of a partial cross section of the image sensor shown in fig. 1a, and as shown in fig. 1a and 1b, the image sensor includes a semiconductor substrate 11 and a lens array 12, the semiconductor substrate 11 is provided with a plurality of pixels, each pixel includes a light sensing unit 112 and a light polarizing unit 113 at least partially embedded in the light sensing unit 112; the lens array 12 is disposed on the semiconductor substrate 11, and the lens array 12 includes a plurality of lens units 121 disposed corresponding to the respective pixels.
The light polarization unit 113 of the image sensor is at least partially embedded in the photosensitive unit 112, and the light polarization unit 113 and the photosensitive unit 112 are arranged at a negative distance, so that the noise reduction effect is good, and the imaging quality can be improved. Since the light polarization unit 113 is disposed at a negative distance from the light sensing unit 112, the size of the image sensor can be reduced, and light and thin can be achieved.
Alternatively, the semiconductor substrate 11 is a silicon material including a p-type dopant such as boron doped, or includes silicon doped with an n-type dopant such as phosphorus or arsenic, or includes other elemental semiconductors such as germanium or diamond.
Alternatively, the incident light enters the photosensitive 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 polarized CMOS image sensor.
Optionally, the light polarization unit 113 includes a plurality of wire grids 1131 disposed at a distance from each other, each wire grid 1131 includes a first side 1132 and a second side 1133 opposite to each other, the first side 1132 faces the lens unit 121, and the second side 1133 is embedded in the photosensitive unit 112. In the present embodiment, the wire grid 1131 of the light polarization unit 113 is formed by wet etching or dry etching; for example, a plurality of first grooves 101 are formed on the surface of each of the photosensitive cells 112 (e.g., the first grooves 101 are formed by etching), then a metal material is formed on the surfaces of the semiconductor substrate 11 and the photosensitive cells 112 (a metal material layer may be formed 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 is filled in the first grooves 101, and finally the metal material outside the first grooves 101 is removed using a Chemical Mechanical Polishing (CMP) or etching process, leaving the metal material in the first grooves 101 to form the wire grids 1131.
Alternatively, the height of each wire grid 1131 from the first side 1132 to the second side 1133 is 200nm to 1000nm, for example, 500nm, 600nm, 800nm may be used.
Optionally, the multiple wire grids 1131 of the light polarization units 113 are parallel to each other, and each wire grid 1131 of the light polarization unit 113 and each wire grid 1131 of an adjacent light polarization unit 113 form an included angle with each other.
Optionally, fig. 2 is a schematic top view of a pixel unit according to the present application, as shown in fig. 2, a plurality of pixels form a pixel array arranged in rows and columns, and the pixel array includes a plurality of pixel units, where each pixel unit includes at least two pixels, and the inclination angles of the wire grids 1131 of the light polarization units 113 corresponding to different pixels in the same pixel unit are different. In this embodiment, the pixel unit includes four pixels, and the four pixels are arranged in a matrix; the wire grids 1131 in the upper left pixel are arranged along the vertical direction, the wire grids 1131 in the upper right pixel are obliquely arranged, and an included angle of 45 degrees is formed between the wire grids 1131 in the upper left pixel and the wire grids 1131 in the upper right pixel; the wire grids 1131 in the lower left pixel are obliquely arranged, 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 horizontally arranged, 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 degrees, namely, each light polarization unit 113 in each pixel unit can provide polarization information of incident light along the following polarization angles: 0 °, 45 °, 90 °, 135 °.
It should be noted that the number of pixels in each pixel unit and the included angle between the wire grids 1131 of the two adjacent light polarization units 113 can be designed according to the actual needs, and the present application is not limited thereto.
Alternatively, the spacing between adjacent wire grids 1131 may be in the range from 100 nanometers (nm) to 500nm (e.g., from 100nm to 500 nm), for example, 200nm, 300nm may be selected; the width of each wire grid 1131 may be in the range from 20nm to 300nm (e.g., from 20nm to 300 nm), for example, 50nm, 100nm may be selected. The above range is preferable based on the wavelength of the incident light.
Optionally, the image sensor further includes a grid frame 13, where 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 through holes 104 disposed corresponding to the pixels, and each light polarization unit 113 is located in each light through hole 104. In the present embodiment, the grill frame 13 is formed by wet etching or dry etching; for example, a second recess 102 is formed in the surface of each semiconductor substrate 11 (e.g., the second recess 102 is formed by etching), then a metal material is formed on the surfaces of the semiconductor substrate 11 and the photosensitive cells 112 (a metal material layer may be formed 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 is filled in the second recess 102, and finally the metal material outside the second recess 102 is removed using a Chemical Mechanical Polishing (CMP) or etching process, i.e., the metal material covering the photosensitive cells 112 is removed, the material in the second recess 102 remains to form the grating frame 13, and the etched-out region forms the light-passing hole 104.
In this embodiment, the first groove 101 and the second groove 102 are formed simultaneously based on the same process step, so that the self-aligned position of the wire grid 1131 and the grid frame 13 can be ensured, which is beneficial to improving the stability and the preparation precision of the device, improving the optical crosstalk resistance of the device, and improving the image quality. Further alternatively, the wire grid 1131 and the grid frame 13 may be formed in the same process based on the first grooves 101 and the second grooves 102, and the overall manufacturing process of the device may be simplified. In other embodiments, the grid frame 13 may be fabricated first and then the wire grid 1131 may be fabricated; the grid frame 13 and the wire grid 1131 may also be fabricated simultaneously. Optionally, the height of the grid frame 13 is greater than or equal to the height of the wire grid 1131.
Optionally, a plurality of spacers 114 are disposed in the semiconductor substrate 11 to space the plurality of photosensitive cells 112 from each other, and the plurality of spacers 114 are disposed corresponding to the grid frame 13. In the present embodiment, the top of the isolation part 114 is flush with the surface of the semiconductor substrate 11, the lower surface of the grid frame 13 extends into the isolation part 114, and the bottom of the isolation part 114 extends to the lower surface of the semiconductor substrate 11; the spacer 114 is arranged opposite the grid frame 13, and the front projection of the grid frame 13 at least partly covers the spacer 114.
Alternatively, the spacers 114 may be trenches etched in the upper and/or lower surfaces of the semiconductor substrate 11 and filled with a dielectric material such as silicon oxide, silicon nitride, silicon oxynitride, fluorosilicate glass (FSG), a low-k dielectric material (e.g., a material having a k value less than 3.9), and/or a suitable insulating material. The isolation portion 114 may include a front side Shallow Trench Isolation (STI) and a back side deep trench isolation (BDTI) correspondingly disposed, and in other embodiments, the isolation portion 114 may be an ion implantation isolation region formed on the front side (e.g., P-type doped isolation structure for an N-type doped photosensitive cell).
Alternatively, both the grid frame 13 and the wire grid 1131 are made of a metal material, the grid frame 13 is the same material as the wire grid 1131, or the grid frame 13 is different material from the wire grid 1131. For example, the material of the grill frame 13 is tungsten, aluminum, or copper; the material of the wire grid 1131 is tungsten, aluminum, or copper. Of course, in other embodiments, the material of the grid frame 13 and the wire grid 1131 may also be different.
Alternatively, fig. 3 is a schematic diagram of a pixel circuit structure of an image processor of the present application, and as shown in fig. 3, a photosensitive unit 112 includes a photosensitive portion PD for converting an optical signal containing image information into an electrical signal during exposure, a transfer transistor TX, a floating diffusion FD, a reset transistor RST, and a source follower transistor SF; the transfer transistor TX connects the photosensitive portion PD and the floating diffusion FD, and transfers an electric signal of the photosensitive portion PD to the floating diffusion FD; the source follower transistor SF is for outputting an electric signal of the floating diffusion FD; the reset transistor RST is used to reset the floating diffusion FD. The semiconductor substrate 11 is subjected to a doping process, such as plasma implantation, so that a photosensitive portion PD, a floating diffusion FD, and source and drain electrodes of the transfer transistor TX, the source follower transistor SF, the reset transistor RST, and the selection transistor RS are formed in the semiconductor substrate 11.
Optionally, the photosensitive unit 112 further includes a selection transistor RS for selectively outputting the electric signal output from the source follower transistor SF to a column line (Pixel out).
Optionally, the image sensor further includes an interconnection structure 14, the interconnection structure 14 is disposed on a side of the semiconductor substrate 11 away from the lens array 12, an interconnection circuit 141 and a conductive pad 142 electrically connected to each photosensitive cell 112 are disposed in the interconnection structure 14, the conductive pad 142 is electrically connected to the interconnection circuit 141, and openings 103 exposing the conductive pad 142 are disposed in the semiconductor substrate 11 and the interconnection structure 14. In this embodiment, the interconnect structure 14 may undergo multiple photolithography, etching, deposition, and planarization operations. Of course, the location of the interconnect structure 14 may also be set according to practical requirements, such as forming an image sensor of the FSI structure.
Optionally, the material of the interconnect circuit 141 and the conductive pad 142 is titanium, tungsten, aluminum or copper, but not limited thereto.
Optionally, the image sensor further includes a color filter 15, the color filter 15 being disposed between the lens array 12 and the light polarization unit 113, the color filter 15 including a plurality of color filter units 151 disposed corresponding to the respective pixels. In the present embodiment, each color filter unit 151 of the color filter 15 may be an R color filter unit that filters red light, a G color filter unit that filters green light, a B color filter unit that filters blue light, or a color filter unit that filters white light, respectively.
It should be noted that the color filter 15 may not be disposed between the lens array 12 and the light polarization unit 113.
Fig. 4 to 12 are schematic flow diagrams of a method for manufacturing an image sensor according to the present application, please refer to fig. 4 to 12, and further provide a method for manufacturing an image sensor according to the present application, the method includes:
providing a semiconductor substrate 11, manufacturing a plurality of photosensitive cells 112 and a plurality of light polarization cells 113 in the semiconductor substrate 11, and embedding each light polarization cell 113 at least partially within each photosensitive cell 112;
the lens array 12 is fabricated on the semiconductor substrate 11 side, and a plurality of lens units 121 of the lens array 12 are provided so as to correspond to the plurality of photosensitive units 112, respectively.
The manufacturing method of the image sensor can embed the light polarization unit 113 into the photosensitive unit 112 at least partially, and the light polarization unit 113 and the photosensitive unit 112 are arranged at a negative distance, so that the noise reduction effect is good, and the imaging quality can be improved. Since the light polarization unit 113 is disposed at a negative distance from the light sensing unit 112, the size of the image sensor can be reduced, and light and thin can be achieved.
Optionally, the method of the light sensing unit 112 and the light polarizing unit 113 includes:
the semiconductor substrate 11 includes a first face 1111 and a second face 1112 opposite to each other, and a plurality of photosensitive cells 112 are formed in the semiconductor substrate 11 from the first face 1111;
thinning the second surface 1112 of the semiconductor substrate 11 to form a third surface 1113 exposing each photosensitive cell 112;
a plurality of first grooves 101 spaced apart from each other are formed on each photosensitive cell 112 from the third face 1113, and a metal material is disposed in each first groove 101 to form a wire grid 1131, and the plurality of wire grids 1131 in each photosensitive cell 112 constitute a light polarization unit 113. In the present embodiment, the semiconductor substrate 11 may be thinned by mechanical grinding and polishing to expose the photosensitive cells 112.
Alternatively, a second groove 102 is formed on the semiconductor substrate 11 from the third face 1113, a metal material is provided in the second groove 102 to form a grating frame 13, the grating frame 13 is provided with a plurality of light-passing holes 104 provided in correspondence with the respective photosensitive cells 112, and the respective light polarization units 113 are located in the respective light-passing holes 104.
Alternatively, the grid frame 13 may be fabricated first, and then the wire grid 1131 may be fabricated; the grid frame 13 and the grid 1131 may also be fabricated simultaneously, for example, by forming a plurality of first grooves 101 spaced apart from each other on each of the photosensitive cells 112 from the third face 1113 and forming the second grooves 102 on the semiconductor substrate 11, for example, by etching the first grooves 101 and the second grooves 102 simultaneously;
thereafter, 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 except the first grooves 101 and the second grooves 102 is etched and removed, a wire grid 1131 is formed in each of the first grooves 101, a grid frame 13 is formed in each of the second grooves 102, wherein a plurality of wire grids 1131 in each of the photosensitive cells 112 form a light polarization unit 113, the grid frame 13 forms a plurality of light through holes 104 disposed corresponding to each of the photosensitive cells 112, and each of the light polarization units 113 is located in each of the light through holes 104.
Alternatively, a plurality of spacers 114 are formed in the semiconductor substrate 11 from the first face 1111 and/or the third face 1113, the plurality of spacers 114 being disposed in correspondence with the grid frame 13, the plurality of spacers 114 being for spacing the plurality of photosensitive cells 112 from each other.
Optionally, the manufacturing method further includes:
after the photosensitive cells 112 are formed, an interconnection structure 14 is prepared on the semiconductor substrate 11, the interconnection structure 14 is arranged on one side of the semiconductor substrate 11 far away from the lens array 12, and an interconnection circuit 141 and a conductive pad 142 which are electrically connected with each photosensitive cell 112 are arranged in the interconnection structure 14;
openings 103 are made in the semiconductor substrate 11 and the interconnect structure 14 exposing the conductive pads 142.
Optionally, the manufacturing method further comprises:
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 disposed between the lens array 12 and the light polarization unit 113, and the color filter 15 includes a plurality of color filter units 151 disposed corresponding to the respective pixels.
Referring to fig. 4 to 12, the process of the method for fabricating an image sensor of the present application includes:
in step one, a first support substrate 21 is provided, and a semiconductor base 11 is provided on the first support substrate 21, as shown in fig. 4. In this example, the first support substrate 21 can be considered as a silicon wafer base, and the semiconductor base 11 is a P-type epitaxial layer (P-Epi) epitaxially formed on the silicon wafer base. Of course, in other embodiments, the first support substrate 21 and the semiconductor base 11 may be integrated material layers, such as Si substrates, and of course, other kinds of substrate structures for manufacturing the image sensor may be used.
Step two, a plurality of photosensitive cells 112 and a plurality of spacers 114 are formed in the semiconductor substrate 11 from the first side 1111 as shown in fig. 5, the plurality of spacers 114 being used to space the plurality of photosensitive cells 112 from each other.
Step three, an interconnect structure 14 is prepared on the first side 1111 of the semiconductor substrate 11, and interconnect circuits 141 and conductive pads 142 electrically connected to the respective photosensitive cells 112 are provided in the interconnect structure 14, as shown in fig. 6.
Step four, a second support substrate 22 is disposed on a side of the interconnect structure 14 away from the semiconductor base 11, the interconnect structure 14 and the first support substrate 21 are flipped over, and then the structure formed in the above steps is flipped over, and the second surface 1112 of the semiconductor base 11 is thinned, so as to form a third surface 1113 exposing each photosensitive cell 112, as shown in fig. 7.
Step five, a plurality of first grooves 101 spaced apart from each other are simultaneously formed on each photosensitive cell 112 from the third face 1113 and second grooves 102 are formed on the semiconductor substrate 11, as shown in fig. 8. In this embodiment, the first groove 101 and the second groove 102 are formed simultaneously based on the same process step, so that the self-aligned position of the wire grid 1131 and the grid frame 13 can be ensured, which is beneficial to improving the stability and the preparation precision of the device, improving the optical crosstalk resistance of the device, and improving the image quality.
Step six, forming a metal material layer on the third surface 1113, removing the metal material except the first grooves 101 and the second grooves 102, forming wire grids 1131 in each first groove 101, forming a grid frame 13 in each second groove 102, wherein a plurality of wire grids 1131 in each photosensitive unit 112 form a light polarization unit 113, forming a plurality of light through holes 104 corresponding to each photosensitive unit 112 on the grid frame 13, and each light polarization unit 113 is located in each light through hole 104, as shown in fig. 9. In other embodiments, the second grooves 102 may be first formed, and the grid frame 13 may be formed in the second grooves 102, then the first grooves 101 may be formed, and then the wire grids 1131 may be formed in the first grooves 101. Of course, the actual design is also possible.
Step seven, openings 103 are made in the semiconductor substrate 11 and the interconnect structure 14 exposing the conductive pads 142, as shown in fig. 10. In the present embodiment, the opening 103 may be formed simultaneously with the first groove 101 and the second groove 102 in the fifth step, and may be freely selected according to practical needs.
Step eight, the color filter 15 is prepared on the light polarization unit 113, and a plurality of color filter units 151 of the color filter 15 are arranged corresponding to a plurality of pixels, as shown in fig. 11.
Step nine, the lens array 12 is prepared on the color filter 15, and a plurality of lens units 121 of the lens array 12 are arranged corresponding to the plurality of photosensitive units 112, respectively, as shown in fig. 12.
The above embodiments are merely illustrative of the principles of the present application and its effectiveness, and are not intended to limit the application. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the application. Accordingly, it is intended that all equivalent modifications and variations of the application be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (17)
1. An image sensor, comprising:
a semiconductor substrate provided with a plurality of pixels, each of the pixels including a light-sensing unit and a light-polarizing unit at least partially embedded in the light-sensing unit;
and the lens array is arranged on the semiconductor substrate and comprises a plurality of lens units which are arranged corresponding to the pixels.
2. The image sensor of claim 1, wherein incident light enters the photosensitive unit from the lens unit via the light polarizing unit.
3. The image sensor of claim 1, wherein the light polarizing element comprises a plurality of spaced apart wire grids, each wire grid comprising opposing first and second sides, the first side facing the lens element and the second side embedded within the photosensitive element.
4. An image sensor as in claim 3, wherein a plurality of said wire grids of said light polarizing units are parallel to each other, each of said wire grids of said light polarizing units being at an angle to each other between each of said wire grids of adjacent said light polarizing units.
5. The image sensor of claim 4, wherein a plurality of the pixels form a pixel array arranged in rows and columns, the pixel array comprising a plurality of pixel cells, wherein each pixel cell comprises at least two of the pixels, and wherein the inclination angles of the wire grids of the light polarization units corresponding to different ones of the pixels in the same pixel cell are different.
6. The image sensor of claim 3, further comprising a grid frame at least partially embedded within the semiconductor substrate, the grid frame having a plurality of light passing holes disposed corresponding to each of the pixels, each of the light polarizing units being located in each of the light passing holes.
7. The image sensor according to claim 6, wherein a plurality of spacers for spacing the photosensitive cells from each other are further provided in the semiconductor substrate, the plurality of spacers being disposed in correspondence with the grid frame; and/or the grating frame and the grating are made of metal materials, wherein the material of the grating frame is the same as that of the grating, or the material of the grating frame is different from that of the grating.
8. The image sensor according to claim 1, wherein the light sensing unit includes a light sensing portion for converting an optical signal containing image information into an electrical signal during exposure, a transfer transistor, a floating diffusion region, a reset transistor, and a source follower transistor; the transmission transistor is connected with the photosensitive part and the floating diffusion region and is used for transferring the electric signal of the photosensitive part to the floating diffusion region; the source follower transistor is used for outputting an electric signal of the floating diffusion region; the reset transistor is used for resetting the floating diffusion region.
9. The image sensor of claim 8, wherein the photosensitive cell further comprises a select transistor for selectively 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, further comprising an interconnect structure provided on a side of the semiconductor substrate remote from the lens array, the interconnect structure having therein an interconnect circuit electrically connected to each of the photosensitive cells and a conductive pad electrically connected to the interconnect circuit, the semiconductor substrate and the interconnect structure having therein an opening exposing the conductive pad; and/or the number of the groups of groups,
the image sensor further includes a color filter disposed between the lens array and the light polarizing unit, the color filter including a plurality of color filter units disposed corresponding to the pixels.
11. A method of manufacturing an image sensor according to any one of claims 1 to 10, comprising:
providing a semiconductor substrate, manufacturing a plurality of photosensitive units and a plurality of light polarization units in the semiconductor substrate, and enabling each light polarization unit to be at least partially embedded into each photosensitive unit;
and manufacturing a lens array on one side of the semiconductor substrate, and arranging a plurality of lens units of the lens array corresponding to the plurality of photosensitive units respectively.
12. The method of manufacturing an image sensor according to claim 11, wherein the method of the light sensing unit and the light polarizing unit includes:
the semiconductor substrate comprises a first surface and a second surface which are opposite, and a plurality of photosensitive units are formed in the semiconductor substrate from the first surface;
thinning the second surface of the semiconductor substrate to form a third surface exposing each photosensitive unit;
and forming a plurality of first grooves which are spaced from each other on each photosensitive unit from the third surface, forming wire grids by arranging metal materials in the first grooves, and forming the light polarization units by the wire grids in the photosensitive units.
13. The method of manufacturing an image sensor according to claim 12, wherein a second recess is formed in the semiconductor substrate from the third face, a metal material is provided in the second recess to form a grid frame, the grid frame is provided with a plurality of light passing holes provided corresponding to the light sensing units, and the light polarization units are located in the light passing holes.
14. The method of manufacturing an image sensor according to claim 13, wherein a plurality of spacers are formed in the semiconductor substrate from the first face and/or the third face, the plurality of spacers being provided in correspondence with the grid frame, the plurality of spacers being for spacing the plurality of photosensitive cells from each other.
15. The method of manufacturing an image sensor according to claim 13, wherein a plurality of first grooves spaced apart from each other are formed on each of the photosensitive cells from the third face at the same time, and a second groove is formed on the semiconductor substrate;
providing a metal material in each first groove to form a wire grid, wherein a plurality of wire grids in each photosensitive unit form the light polarization unit; and a metal material is arranged in the second groove to form a grid frame, the grid frame is provided with a plurality of light through holes which are arranged corresponding to the photosensitive units, and the light polarization units are positioned in the light through holes.
16. The method of manufacturing an image sensor according to any one of claims 11 to 15, further comprising:
after the photosensitive units are formed, preparing an interconnection structure on the semiconductor substrate, wherein the interconnection structure is arranged on one side of the semiconductor substrate, which is far away from the lens array, and an interconnection circuit and a conductive disc which are electrically connected with each photosensitive unit are arranged in the interconnection structure;
openings are made in the semiconductor substrate and the interconnect structure exposing the conductive pads.
17. The method of manufacturing an image sensor according to any one of claims 11 to 15, further comprising:
after the light polarization unit is formed, a color filter is prepared on the light polarization unit, the color filter is arranged between the lens array and the light polarization unit, and the color filter comprises a plurality of color filtering units which are arranged corresponding to the pixels.
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| CN202210483022.2A CN117080227A (en) | 2022-05-05 | 2022-05-05 | Image sensor and method for manufacturing the same |
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| CN202210483022.2A CN117080227A (en) | 2022-05-05 | 2022-05-05 | Image sensor and method for manufacturing the same |
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