Imaging system, image sensor and preparation method thereof

Abstract

The embodiment of the invention relates to the field of semiconductors, and provides an imaging system, an image sensor and a preparation method thereof, and the system comprises a substrate which comprises a plurality of pixel units and an isolation structure for separating the plurality of pixel units; the color filters are located on the substrate, and each color filter corresponds to one pixel unit; the color filter comprises a plurality of color filters, a plurality of grid structures, the grid structures are located between the adjacent color filters, the grid structures form a plurality of first grid patterns and a plurality of second grid patterns, each first grid pattern and each second grid pattern respectively correspond to one pixel unit, and the area of the first grid patterns is larger than that of the second grid patterns.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of semiconductors, and particularly to an imaging system, an image sensor, and a method for manufacturing the same. Background Art

[0002] An image sensor is a semiconductor device that converts optical information into an electrical signal. For example, an image sensor can convert the variable attenuation of light waves into a signal (i.e., a small current burst that conveys information). Such image sensors can include charge-coupled device (CCD) image sensors and complementary metal-oxide-semiconductor (CMOS) image sensors. High Dynamic Range (HDR) imaging technology is very important in the field of image sensors. Especially when facing extreme lighting conditions, the introduction of HDR technology aims to expand the dynamic range of the sensor so that it can capture a wider range of lighting, thereby improving image quality and meeting the needs of different fields. Although the deficiency in the dynamic range of the sensor can be compensated by software processing and shooting techniques, it is still preferred that the sensor itself has a high dynamic range. Therefore, it is necessary to propose a new image sensor and a method for manufacturing the same to achieve the high dynamic range of the image sensor. Summary of the Invention

[0003] According to some embodiments of the present disclosure, on the one hand, an image sensor is provided, including:

[0004] a substrate including a plurality of pixel units and an isolation structure separating the plurality of pixel units;

[0005] a plurality of color filters located on the substrate, each color filter corresponding to one of the pixel units;

[0006] a plurality of grid structures located on the substrate between adjacent color filters, the plurality of grid structures constituting a plurality of first grid patterns and a plurality of second grid patterns, each first grid pattern and each second grid pattern corresponding to one of the pixel units, wherein the area of the first grid pattern is larger than the area of the second grid pattern.

[0007] In some embodiments, the area of the pixel unit corresponding to the first grid pattern is equal to the area of the pixel unit corresponding to the second grid pattern.

[0008] In some embodiments, at least one first grid pattern and at least three second grid patterns form a repeating unit, and the repeating units are arranged periodically in a first direction and a second direction.

[0009] In some embodiments, at least one of the first grid patterns and at least one of the second grid patterns form a repeating unit, and the repeating units are arranged periodically in a first direction and a second direction.

[0010] In some embodiments, at least three of the first grid patterns and at least one of the second grid patterns form a repeating unit, and the repeating units are arranged periodically in a first direction and a second direction.

[0011] In some embodiments, the grid structure includes a first grid structure and a second grid structure, wherein the width of the first grid structure is greater than that of the second grid structure.

[0012] In some embodiments, the second grid pattern is formed by the first grid structure, and the first grid pattern is formed by the first grid structure and / or the second grid structure.

[0013] In some embodiments, the grid structure includes a conductive layer and an oxide layer stacked in sequence.

[0014] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a method for manufacturing an image sensor, including: providing a substrate, in which a plurality of pixel units and an isolation structure for separating the plurality of pixel units are formed;

[0015] Forming a plurality of grid structures, the grid structures are formed on the substrate, and the plurality of grid structures constitute a plurality of first grid patterns and a plurality of second grid patterns, and each of the first grid patterns and each of the second grid patterns respectively corresponds to one of the pixel units, wherein the area of the first grid pattern is greater than the area of the second grid pattern;

[0016] Forming a plurality of color filters, the color filters are formed on the substrate, and each of the color filters corresponds to one of the pixel units, and the grid structure is located between adjacent color filters.

[0017] In some embodiments, the step of forming the grid structure includes: sequentially stacking and depositing a conductive layer and an oxide layer on the substrate, and patterning the conductive layer and the oxide layer to form the grid structure.

[0018] In some embodiments, the step of forming a plurality of color filters includes: depositing a color filter material on the substrate and the grid structure to form a plurality of color filters separated by the grid structure.

[0019] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides an imaging system, including: a processor and a memory; a camera, the camera includes a lens and the image sensor prepared by the image sensor or the manufacturing method.

[0020] According to an embodiment of the present disclosure, by forming a plurality of grid structures between adjacent color filters on a substrate, and forming a plurality of first grid patterns and a plurality of second grid patterns from the plurality of grid structures, each first grid pattern and each second grid pattern respectively correspond to one of the pixel units, wherein the area of the first grid pattern is larger than the area of the second grid pattern, thereby achieving the absorption of light with different dynamic ranges by the image sensor. Description of the Drawings

[0021] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a scale limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1(a)-1(c) It is a top view schematic diagram of a partial structure of the image sensor in the embodiment of the present disclosure.

[0023] Figure 2 It is a cross-sectional view of the image sensor in the embodiment of the present disclosure along the A-A' or B-B' direction in Fig. 1(a).

[0024] Figure 3 It is a circuit schematic diagram of the pixel unit of the image sensor in the embodiment of the present disclosure.

[0025] Figure 4 It is a schematic flowchart of a method for manufacturing an image sensor provided.

[0026] Figures 5 to 8 It is a schematic diagram of the cross-sectional structure corresponding to each step of a method for manufacturing an image sensor provided in the embodiment of the present disclosure along the A-A' or B-B' direction in Fig. 1(a).

[0027] Figure 9(a)-9(b) It is a schematic diagram of the cross-sectional structure corresponding to each step of a method for manufacturing an image sensor provided in the embodiment of the present disclosure along the A-A' direction and the B-B' direction in Fig. 1(a), respectively.

[0028] Figure 10 It is a schematic diagram of the cross-sectional structure corresponding to each step of a method for manufacturing an image sensor provided in the embodiment of the present disclosure along the A-A' or B-B' direction in Fig. 1(a).

[0029] Figure 11 It is a schematic diagram of an imaging system provided in the embodiment of the present disclosure. Detailed implementation manners

[0030] The following will elaborate on the embodiments of the present disclosure in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are presented to help readers better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0031] Image sensors are essential key components in modern electronic devices, and their core function is to achieve efficient conversion of optical signals into electrical signals. This process involves complex optoelectronic conversion mechanisms, where the image sensor converts incident photons into electrons through photodiodes and then outputs readable electrical signals through a series of signal processing circuits. The performance of the image sensor directly determines the quality of the imaging system, and its key indicators include sensitivity, noise level, dynamic range, and response speed, etc. In practical applications, image sensors need to maintain stable and reliable performance under different lighting conditions, which poses extremely high requirements for the design and manufacturing of the sensors.

[0032] Precisely based on this basic function of the image sensor, the High Dynamic Range (HDR) imaging technology has been realized and plays an important role. The HDR technology expands the dynamic range of the sensor, enabling it to capture details from highlights to shadows more accurately, thereby significantly improving the image quality. Therefore, the design of the image sensor not only needs to consider its basic optoelectronic signal conversion ability but also pay attention to its adaptability under different lighting conditions to meet the growing demand for high-quality images. Although the deficiency in the dynamic range of the sensor can be compensated to a certain extent through post-processing software and shooting techniques, the high dynamic range of the sensor itself remains the basis for achieving high-quality imaging. Especially in complex lighting environments, the performance of the sensor often becomes the key factor determining the image quality.

[0033] Therefore, the embodiments of the present disclosure propose a new image sensor and its manufacturing method to achieve the high dynamic range of the image sensor. The following will explain the image sensor and its manufacturing method provided by the embodiments of the present disclosure in conjunction with the accompanying drawings. Figure 1(a)-1(c) is a top view schematic diagram of a partial structure of the image sensor in the embodiment of the present disclosure; Figure 2 is a cross-sectional view of the image sensor in the embodiment of the present disclosure along the direction of A-A' or B-B' in FIG. 1(a); Figure 3 is a circuit schematic diagram of the pixel unit of the image sensor in the embodiment of the present disclosure.

[0034] Refer to FIG. 1- Figure 3, the image sensor 10 provided by the embodiments of the present disclosure includes: a substrate 101, including a plurality of pixel units 102 and an isolation structure 103 for separating the plurality of pixel units 102.

[0035] A plurality of color filters 109 are located on the substrate 101, and each color filter 109 corresponds to one pixel unit 102;

[0036] A plurality of grid structures GD are located on the substrate 101 between adjacent color filters 109. The plurality of grid structures GD form a plurality of first grid patterns P1 and a plurality of second grid patterns P2. Each first grid pattern P1 and each second grid pattern P2 respectively correspond to one pixel unit 102. Among them, the area of the first grid pattern P1 is larger than the area of the second grid pattern P2. The following will be described in detail with reference to the accompanying drawings.

[0037] Reference Figure 2 , the substrate 101 includes a plurality of pixel units 102 and an isolation structure 103 for separating the plurality of pixel units 102. Among them, the substrate 101 can be silicon-on-insulator (SOI), or a silicon substrate, or made of materials such as silicon germanium, indium antimonide, lead telluride, indium arsenide, indium phosphide, gallium arsenide, or gallium antimonide.

[0038] Reference Figures 2 - 3, each pixel unit 102 may include a photoelectric conversion layer PD, a transfer transistor TG, a floating diffusion region FD, a reset transistor RST, a source follower transistor SF, and a selection transistor SEL. The photoelectric conversion layer PD can generate charges proportional to the amount of light incident from the outside. The photoelectric conversion layer PD may be coupled to the transfer transistor TG that transfers the generated and accumulated charges to the floating diffusion region FD. The floating diffusion region FD is a region that converts charges into a voltage and can cumulatively store charges due to its parasitic capacitance. One end of the transfer transistor TG may be connected to the photoelectric conversion layer PD, and the other end of the transfer transistor TG may be connected to the floating diffusion region FD. The transfer transistor TG may be a transistor driven by a predetermined bias voltage, for example, a transfer signal TX. The transfer transistor TG may transfer the charges generated by the photoelectric conversion layer PD to the floating diffusion region FD according to the transfer signal TX. The source follower transistor SF may amplify the potential change of the floating diffusion region FD that receives charges from the photoelectric conversion layer PD, and may output the amplified change to the output line Vout. When the source follower transistor SF is turned on, a predetermined potential, for example, a power supply voltage VDD, provided to the drain of the source follower transistor SF may be transferred to the drain region of the selection transistor SEL. The selection transistor SEL may select the unit pixel to be read row by row. The selection transistor SEL may be a transistor driven by a selection line that applies a predetermined bias voltage, for example, a row selection signal RS. The reset transistor RST may periodically reset the floating diffusion region FD. The reset transistor RST may be driven by a reset line that applies a predetermined bias voltage, for example, a reset signal RX. When the reset transistor RST is turned on by the reset signal RX, a predetermined potential, for example, a power supply voltage VDD, provided to the drain of the reset transistor RST may be transferred to the floating diffusion region FD.

[0039] Continue to refer to Figure 2, an isolation structure 103 is further provided between multiple pixel units 102. Exemplarily, the isolation structure 103 may be a Deep Trench Isolation (DTI), which can extend from the surface of the substrate 101 into the substrate to isolate adjacent pixel units 102. In some embodiments, the width of the isolation structure 103 may gradually decrease along the direction towards the substrate 101. The isolation structure 103 may be filled with a first dielectric layer 104 and a second dielectric layer 105. Wherein, the materials of the first dielectric layer 104 and the second dielectric layer 105 may both be silicon oxide or other high-k materials, for example, materials such as silicon oxide (SiO2), hafnium oxide (HfO2), tantalum oxide (Ta2O5), titanium oxide (TiO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), etc. In other embodiments, the isolation structure 103 may also be a single-layer structure, that is, it may only include the first dielectric layer 104 or the second dielectric layer 105. Exemplarily, the first dielectric layer 104 may be aluminum oxide (Al2O3), and the second dielectric layer 105 may be (SiO2), or a three-layer or multi-layer stacked structure, that is, it may include the first dielectric layer 104 and the second dielectric layer 105, and other dielectric layers may also be provided. Exemplarily, the first dielectric layer 104 may be aluminum oxide (Al2O3), the second dielectric layer 105 may be (SiO2), and the other dielectric layer may include tantalum oxide (Ta2O5), or on the basis of the above embodiments, an air gap may also be provided in the second dielectric layer 105. The first dielectric layer 104 and the second dielectric layer 105 fill the isolation structure 103 and may also extend to the surface of the substrate 101. By providing the isolation structure 103 between adjacent pixel units 102 and forming a physical barrier through the first dielectric layer 104 and the second dielectric layer 105 of the isolation structure 103, charge diffusion or parasitic current between adjacent pixel units 102 can be effectively blocked, thereby reducing dark current and crosstalk and improving image quality.

[0040] Multiple color filters 109 are located on the substrate 101 and are correspondingly arranged with multiple pixel units 102. In some embodiments, the color filters 109 may include red color filters, green color filters, blue color filters, infrared (IR) color filters, transparent color filters or color filters of other colors. Exemplarily, the color filters may also be arranged in a Bayer pattern or any other suitable pattern. A microlens 110 may also be provided above the color filter 109. The microlens 110 may be semi-elliptical to guide the light incident on the color filter 109 to the corresponding pixel unit 102. Wherein, the microlens 110 may be an optically transparent material, for example, a transparent polymer material based on polystyrene resin, polyimide resin, polysiloxane resin, acrylic resin, epoxy resin or their copolymer resins, or an inorganic material based on silicon oxide or silicon nitride.

[0041] In some embodiments, a protective layer 111 is further disposed on the microlens 110. The protective layer 111 can be conformally disposed on the upper surface of the microlens 110. For example, it can be set as a hemispherical curved surface, so as to cooperate with the microlens 110 to increase or decrease the focal length while protecting the microlens 110, thereby improving the resolution of the image. Exemplarily, the material of the protective layer 111 can be an inorganic oxide layer, including but not limited to at least one or more of silicon oxide, titanium oxide, zirconium oxide, and hafnium oxide.

[0042] Referring to FIG. 1- Figure 2 , the grid structure GD is on the substrate 101 between adjacent color filters 109 and extends along the first direction X and the second direction Y respectively. A plurality of grid structures GD form a plurality of first grid patterns P1 and a plurality of second grid patterns P2. Each first grid pattern P1 and each second grid pattern P2 respectively correspond to a pixel unit 102. Among them, the area of the first grid pattern P1 is larger than the area of the second grid pattern P2. Exemplarily, both the first grid pattern P1 and the second grid pattern P2 can be squares, and the side length ratio W1 / W2 of the first grid pattern P1 and the second grid pattern P2 is N, where N is a positive integer greater than 1. For example, the side length W1 of the first grid pattern P1 can be 1 μm, and the side length W2 of the second grid pattern P2 can be 0.5 μm, then W1 / W2 = 2. The larger the value of W1 / W2, the greater the area difference between the first grid pattern P1 and the second grid pattern P2, so that P1 and P2 show different sensitivities and dynamic ranges when capturing optical signals; specifically, the first grid pattern P1 with a larger area is more sensitive to light, can capture more photons, is suitable for signal acquisition in low-light areas, reduces noise interference, and improves the signal-to-noise ratio. The smaller second grid pattern P2 is less likely to reach saturation, and the smaller window can better passivate the incident light and capture the signal in the high-light area, thereby avoiding overexposure under strong light conditions. Through this complementary design, the sensor can achieve a wider dynamic range under different lighting conditions, thereby capturing richer image details. In addition, the larger P1 and the smaller P2 also show significant advantages in terms of spatial resolution and noise control. The larger P1 can provide a higher spatial resolution in the high-light area, while the smaller P2 can better suppress noise in the low-light area, thereby achieving the overall dynamic range and improving the image quality. This design can not only meet the requirements of high dynamic range, but also simplify the manufacturing process and improve production efficiency.

[0043] The image sensor further includes an analog-to-digital converter (ADC) to convert the optical signal into a digital image. A high-resolution ADC can better preserve the details of highlights and shadows, reduce overexposure or underexposure, thereby improving the high dynamic range. Generally, for a specific image sensor, the resolution of the ADC is fixed. In some embodiments, the first grid pattern P1 and the second grid pattern P2 can form repeating units of different combinations, so that the high dynamic range of the image sensor can be achieved with a fixed ADC resolution. Exemplarily, referring to Figure 1(a)-1(c) , the repeating unit U1 can be composed of one first grid pattern P1 and at least three of the second grid pattern P2; the repeating unit U2 can be composed of at least one first grid pattern P1 and at least one second grid pattern P2; the repeating unit U3 can be composed of at least three first grid pattern P1 and at least one second grid pattern P2. Among them, the repeating units U1, U2, and U3 are all periodically arranged along the first direction X and the second direction Y. The ADC in the same image sensor can adapt to different repeating units U1, U2, and U3 to meet the requirements of different high dynamic ranges.

[0044] In some embodiments, continuing to refer to Figure 2 and FIG. 9, the grid structure GD can include a first grid structure GD1 and a second grid structure GD2. Among them, the width W3 of the first grid structure GD1 is greater than the width W4 of the second grid structure GD2. Exemplarily, the range of the width W3 of the first grid structure GD1 can be 300-500 nm, and the range of the width W4 of the second grid structure GD2 can be 50-200 nm to form the first grid pattern P1 and the second grid pattern P2 with different areas.

[0045] In some embodiments, continuing to refer to Figure 1(a)-1(c), the second grid pattern P2 can be formed by the first grid structure GD1, and the first grid pattern P1 can be formed by the first grid structure GD1 and / or the second grid structure GD2. For example, referring to FIG. 1(a), the second grid pattern P2 in the repeating unit U1 can be formed by the first grid structure GD1, and the first grid pattern P1 can be formed jointly by the first grid structure GD1 and the second grid structure GD2 or only by the first grid structure GD1; referring to FIG. 1(b), the second grid pattern P2 in the repeating unit U2 is formed by the first grid structure GD1, and the first grid pattern P1 is formed by the first grid structure GD1 and the second grid structure GD2; referring to FIG. 1(c), the second grid pattern P2 in the repeating unit U3 can be formed by the first grid structure GD1, and the first grid pattern P1 can also be formed by the first grid structure GD1. By setting the first grid structure GD1 and the second grid structure GD2 to have different widths in the above three ways, the arrangements of the first grid pattern P1 and the second grid pattern P2 with different areas can be realized, thereby effectively meeting the high dynamic range requirements of the image sensor.

[0046] In some embodiments, the area of the pixel unit 102 corresponding to the first grid pattern P1 may be equal to the area of the pixel unit 102 corresponding to the second grid pattern P2. Exemplarily, referring to FIGS. 1- Figure 2 , the areas of the pixel units 102 corresponding to the first grid pattern P1 and the second grid pattern P2 with different areas may be the same, that is, on the basis of not changing the area of the pixel unit 102, by setting the areas of the first grid pattern P1 and the second grid pattern P2 to be different, the high dynamic range of the image sensor can be realized, which is beneficial to further simplifying the manufacturing process and improving the production efficiency.

[0047] In some embodiments, referring to Figure 2 , the grid structure GD may include a conductive layer 106 and an oxide layer 107 stacked in sequence. Among them, the material of the oxide layer 107 may include, but is not limited to, at least one of silicon oxide, aluminum oxide, tantalum oxide, and their combinations, and the material of the conductive layer 106 may be tungsten, titanium, or tantalum. When light is incident on the grid structure GD from the color filter 109, reflection can occur on the surface of the conductive layer 106 of the grid structure GD, reflecting the light back to the corresponding pixel unit and deviating the light from other pixel units, thereby effectively avoiding optical crosstalk between adjacent pixel units; the refractive index of the oxide layer 107 is between that of the color filter 109 and the conductive layer 106, which can reduce the light reflection loss at the interface and improve the utilization rate of incident light. At the same time, the oxide layer 107 can alleviate the difference in thermal expansion coefficients between the metal and the color filter material (such as resin) and avoid cracking.

[0048] Correspondingly, another embodiment of the present disclosure provides a method for manufacturing an image sensor, which can be used to form the above image sensor.

[0049] Figure 4 Schematic flow chart of a method for manufacturing an image sensor provided; Figures 5 to 8 Schematic cross-sectional view structure corresponding to each step of a method for manufacturing an image sensor provided by an embodiment of the present disclosure along the A-A' or B-B' direction in FIG. 1(a);

[0050] Figure 9(a)-9(b) Schematic cross-sectional view structures corresponding to each step of a method for manufacturing an image sensor provided by an embodiment of the present disclosure along the A-A' direction and the B-B' direction in FIG. 1(a); Figure 10 Schematic cross-sectional view structure corresponding to each step of a method for manufacturing an image sensor provided by an embodiment of the present disclosure along the A-A' or B-B' direction. The method for manufacturing the image sensor provided in this embodiment will be described in detail below. Parts that are the same as or corresponding to the above embodiments will not be described in detail below.

[0051] Step S100 provides a substrate 101, in which a plurality of pixel units 102 and an isolation structure 103 for separating the plurality of pixel units 102 are formed.

[0052] In some embodiments, referring to Figure 5 , the substrate 101 may be a semiconductor material of other elements such as silicon on insulator (SOI), germanium or diamond, or may be prepared from materials such as silicon germanium, indium antimonide, lead telluride, indium arsenide, indium phosphide, gallium arsenide or gallium antimonide. The substrate 101 may also be a doped silicon substrate. For example, the substrate 101 may be a silicon substrate doped with an N-type dopant such as phosphorus or arsenic.

[0053] Referring to Figures 2 - 5 , each pixel unit 102 may include a photoelectric conversion layer PD, a transfer transistor TG, a floating diffusion region FD, a reset transistor RST, a source follower transistor SF, and a selection transistor SEL. Light is converted into an electrical signal through the photoelectric conversion layer PD, wherein the incident light may be visible light. For example, the incident light may be infrared (IR), ultraviolet (UV), X-ray, microwave, other suitable types of light, or a combination thereof.

[0054] Ion implantation is performed on the substrate 101 to form pixel units 102. The pixel unit 102 includes a photoelectric conversion layer PD that can convert an optical signal into an electrical signal, and the pixel unit 102 is in contact with the substrate 101. In this embodiment, for forming the pixel unit 102, the type of ions implanted into the substrate 101 is not limited, and the required photoelectric conversion layer PD, transfer transistor TG, floating diffusion region FD, reset transistor RST, source follower transistor SF, and selection transistor SEL devices can be formed. Exemplarily, if the substrate 101 is P-type doped, then N-type ions are implanted into the substrate 101, and the implanted ions can specifically be ions with five valence electrons, such as phosphorus ions or arsenic ions. When a phosphorus ion replaces a silicon atom, it provides a negatively charged electron to the valence band of the crystal, thereby forming the pixel unit 102 of an N-type photodiode. In other embodiments, when the substrate 101 is N-type doped, P-type ions can also be implanted into the substrate 101 to form the pixel unit 102 of a P-type photodiode. During the process of forming the pixel unit 102, to ensure the yield of the pixel unit 102 formed after ion implantation, ion implantation at multiple different angles can be performed to form the pixel unit 102 that conforms to a preset pattern.

[0055] The substrate 101 is etched to form trenches, and a first dielectric layer 104 and a second dielectric layer 105 are filled in the trenches to form an isolation structure 103. The materials of the first dielectric layer 104 and the second dielectric layer 105 can both be silicon oxide or other high-k materials, such as materials like silicon oxide (SiO2), hafnium oxide (HfO2), tantalum oxide (Ta2O5), titanium oxide (TiO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), etc. The deposition process for filling the first dielectric layer 104 and the second dielectric layer 105 can include Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), Atomic Layer Deposition (ALD), or other deposition processes. Among them, the deposition processes of the first dielectric layer 104 and the second dielectric layer 105 can be repeated or alternated to form a single-layer or multi-layer dielectric layer. The first dielectric layer 104 and the second dielectric layer 105 fill the isolation structure 103 and can also extend to the surface of the substrate 101.

[0056] Step S200 forms a plurality of grid structures GD. The grid structures GD are formed on the substrate 101. The plurality of grid structures GD constitute a plurality of first grid patterns P1 and a plurality of second grid patterns P2. Each first grid pattern P1 and each second grid pattern P2 correspond to a pixel unit 102 respectively, wherein the area of the first grid pattern P1 is larger than the area of the second grid pattern P2.

[0057] In some embodiments, referring to Figure 6 - FIG. 9, a conductive layer 106, an oxide layer 107, and a photoresist layer 108 are sequentially stacked and deposited on a substrate 101. Exemplarily, the conductive layer 106, the oxide layer 107, and the photoresist layer 108 are sequentially deposited on a second dielectric layer 105 on the substrate 101. In some embodiments, the material of the oxide layer 107 may include, but is not limited to, at least one of silicon oxide, aluminum oxide, tantalum oxide, and combinations thereof. The material of the conductive layer 106 may be tungsten, titanium, or tantalum. Among them, the deposition processes of the conductive layer 106 and the oxide layer 107 may include electroplating, sputtering, CVD, PVD, or other deposition processes. Among them, the CVD process may include PECVD, LPCVD, or ALD.

[0058] The photoresist layer 108 is patterned, and the conductive layer 106 and the oxide layer 107 are etched using the patterned photoresist layer 108 as a mask to form a plurality of grid structures GD. The plurality of grid structures GD constitute a plurality of first grid patterns P1 and a plurality of second grid patterns P2. Each first grid pattern P1 and each second grid pattern P2 respectively correspond to a pixel unit 102. Among them, the area of the first grid pattern P1 is larger than the area of the second grid pattern P2. The patterning process may be dry etching.

[0059] In some embodiments, the width range of the first grid structure GD1 may be 300-500 nm, and the width range of the second grid structure GD2 may be 50-200 nm to form first grid patterns P1 and second grid patterns P2 with different areas.

[0060] S300 forms a plurality of color filters 109. The color filters are formed on the substrate 101. Each color filter 109 corresponds to a pixel unit 102. The grid structure GD is located between adjacent color filters 109.

[0061] In some embodiments, referring to Figure 9(a)-9(b) and Figure 10, after forming the grid structure GD, a color filter material is deposited on the substrate 101 and the grid structure GD to form a plurality of color filters 109 spaced apart by the grid structure GD. Exemplarily, the color filters 109 are formed on the second dielectric layer 105 between the grid structures GD, and each color filter 109 is correspondingly disposed on a respective pixel unit 102. The material of the color filter 109 may include, but is not limited to, colored or dyed materials, such as acrylic acid. For example, polymethyl methacrylate (“PMMA”) or propylene glycol monostearate (“PGMS”), which can be used to add pigments or dyes to form the color filter, may also include silicon oxide, silicon nitride, or other suitable polymers, and can be formed by processes such as CVD, PVD, or a combination thereof. The thickness of the color filter 109 may be greater than the thickness of the grid structure GD, and the color filter 109 may cover the grid structure GD.

[0062] In some embodiments, the color filters 109 may include red color filters, green color filters, blue color filters, infrared (IR) color filters, transparent color filters, or color filters of other colors. Exemplarily, the color filters may also be arranged in a Bayer pattern or any other suitable pattern. For example, the color filters 109 may include one or more of red (R), green (G), and blue (B) color filters that transmit light in the red, green, and blue spectral ranges. The R, G, and B type color filters 109 are arranged in a repeating RGB pattern in each pixel row of the image sensor 10. In addition, the color filters 109 may also be configured to have different types of color filters 109, such as red, green, blue, and infrared.

[0063] In some embodiments, microlenses 110 may also be formed above the color filters 109. The microlenses 110 may be semi-elliptical to direct the incident light onto the corresponding pixel units 102. Among them, the microlenses 110 may be made of transparent organic materials or inorganic compound materials. For example, transparent polymer materials based on polystyrene resins, polyimide resins, polysiloxane resins, acrylic resins, epoxy resin-based resins, or their copolymer resins, or inorganic materials based on silicon oxide or silicon nitride. In some embodiments, a protective layer 111 may also be formed on the microlenses 110. The protective layer 111 may be conformally formed on the upper surface of the microlenses 110. For example, it may be set as a hemispherical curved surface to, while protecting the microlenses 110, also cooperate with the microlenses 110 to increase or decrease the focal length to improve the resolution of the image. Exemplarily, the material of the protective layer 111 may be an inorganic oxide layer, including but not limited to at least one or more of silicon oxide, titanium oxide, zirconium oxide, and hafnium oxide.

[0064] The embodiments of the present disclosure also provide an imaging system 50. Refer toFigure 11 The imaging system 50 uses the above-described image sensor 10 to capture images. Figure 11 The imaging system 50 can be a portable electronic device, such as a camera, a mobile phone, a tablet computer, a web camera, a video camera, a video surveillance system, an automotive imaging system, a video game system with imaging capabilities, or any other desired imaging system or device that captures digital image data. The camera module 30 can be used to convert incident light into digital image data. The camera module 30 can include a lens 20 and a corresponding image sensor 10. The lens 20 can include a fixed lens and / or an adjustable lens, and can include microlenses formed on the imaging surface of the image sensor 10. During an image capture operation, light from a scene can be focused onto the image sensor 10 through the lens 20. The image sensor 10 can include circuitry for converting analog pixel data into corresponding digital image data to be provided to the storage and processing circuitry 40. If desired, the camera module 30 can be provided with an array of lenses 20 and an array of corresponding image sensors 10.

[0065] The storage and processing circuitry 40 can include one or more integrated circuits, such as a memory and a processor (e.g., an image processing circuit, a microprocessor, storage devices such as a random access memory and a non-volatile memory, etc.), and can be implemented using components separate from and / or forming part of the camera module 30 (e.g., circuitry forming part of an integrated circuit including the image sensor 10 or an integrated circuit within a module associated with the image sensor 10). The image data captured by the camera module 30 can be processed and stored using the processing circuitry 40 (e.g., using an image processing engine on the processing circuitry 40, using an imaging mode selection engine on the processing circuitry 40, etc.). The processed image data can be provided to an external device (e.g., a computer, an external display, or other device) using a wired and / or wireless communication path coupled to the processing circuitry 40 as needed.

[0066] In summary, according to an embodiment of the present disclosure, by forming a plurality of grid structures between adjacent color filters on a substrate, and forming a plurality of first grid patterns and a plurality of second grid patterns from the plurality of grid structures, each first grid pattern and each second grid pattern corresponding to one of the pixel units, wherein the area of the first grid pattern is larger than the area of the second grid pattern, absorption of light with different dynamic ranges by the image sensor is achieved.

[0067] Those of ordinary skill in the art will understand that the above-described embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. An image sensor, characterized in that: include: A substrate, comprising a plurality of pixel units and an isolation structure separating the plurality of pixel units; A plurality of color filters are located on the substrate, each of the color filters corresponding to one of the pixel units; A plurality of grid structures are provided, wherein the grid structures are located on the substrate between adjacent color filters, and the plurality of grid structures constitute a plurality of first grid patterns and a plurality of second grid patterns, each of the first grid patterns and each of the second grid patterns corresponds to one pixel unit, respectively, wherein an area of ​​the first grid pattern is greater than an area of ​​the second grid pattern.

2. The image sensor according to claim 1, characterized in that The area of ​​the pixel unit corresponding to the first grid pattern is equal to the area of ​​the pixel unit corresponding to the second grid pattern.

3. The image sensor according to claim 1, characterized in that At least one of the first grid patterns and at least three of the second grid patterns constitute a repeating unit, and the repeating unit is periodically arranged along a first direction and a second direction.

4. The image sensor according to claim 1, characterized in that At least one of the first grid patterns and at least one of the second grid patterns constitute a repeating unit, and the repeating unit is periodically arranged along a first direction and a second direction.

5. The image sensor according to claim 1, characterized in that At least three of the first grid patterns and at least one of the second grid patterns constitute a repeating unit, and the repeating unit is periodically arranged along a first direction and a second direction.

6. The image sensor according to any one of claims 1 to 5, characterized in that: The grid structure includes a first grid structure and a second grid structure, wherein the first grid structure is wider than the second grid structure.

7. The image sensor according to claim 6, characterized in that: The second grid pattern is composed of the first grid structure, and the first grid pattern is composed of the first grid structure and / or the second grid structure.

8. The image sensor according to claim 1, characterized in that The grid structure includes a conductive layer and an oxide layer stacked in sequence.

9. A method for preparing an image sensor, characterized in that: include: Providing a substrate, wherein a plurality of pixel units and an isolation structure for separating the plurality of pixel units are formed in the substrate; forming a plurality of grid structures, wherein the grid structures are formed on the substrate, the plurality of grid structures constitute a plurality of first grid patterns and a plurality of second grid patterns, each of the first grid patterns and each of the second grid patterns respectively corresponds to one of the pixel units, wherein an area of ​​the first grid pattern is greater than an area of ​​the second grid pattern; A plurality of color filters are formed on the substrate, each of the color filters corresponds to one of the pixel units, and the grid structure is located between adjacent color filters.

10. The method for preparing an image sensor according to claim 9, characterized in that: The step of forming the grid structure includes: sequentially stacking and depositing a conductive layer and an oxide layer on the substrate, and patterning the conductive layer and the oxide layer to form the grid structure.

11. The method for preparing an image sensor according to claim 9, characterized in that: The steps of forming a plurality of color filters include: A color filter material is deposited on the substrate and the grid structure to form a plurality of the color filters separated by the grid structure.

12. An imaging system, characterized in that: include: Processor and memory; A camera, comprising a lens and an image sensor prepared by the image sensor according to any one of claims 1 to 8 or the preparation method according to any one of claims 9 to 11.

Images