Image sensor and method of manufacturing the same

Abstract

This invention discloses an image sensor and its fabrication method, belonging to the field of semiconductor technology. The image sensor includes: a substrate; a photodiode disposed in the substrate, wherein the photodiode has a first recess; a deep trench isolation structure disposed in the substrate, wherein the deep trench isolation structure is located between adjacent photodiodes, the deep trench isolation structure including a light-transmitting graphene layer, the light-transmitting graphene layer being bonded to the photodiode; and a photoresponse region, wherein the photoresponse region is formed by filling the first recess with the graphene layer, and the depth of the photoresponse region first increases and then decreases along the width direction of the photoresponse region. The image sensor and its fabrication method provided by this invention can improve the light response range and efficiency of the image sensor.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and specifically relates to an image sensor and its manufacturing method. Background Technology

[0002] Image sensors are devices that convert light signals into electrical signals and are widely used in fields such as photography, security systems, smartphones, fax machines, scanners, and medical electronics.

[0003] The photodiodes in an image sensor can sense light signals and convert them into electrical signals. Due to the inherent physical properties of silicon, silicon-based image sensors have very little response to near-infrared light, especially near-infrared light greater than 1000nm, resulting in low photoelectric conversion efficiency and making it difficult for image sensors to meet market demands. Summary of the Invention

[0004] The purpose of this invention is to provide an image sensor and a method for manufacturing the same, which can improve the performance of the image sensor, reduce leakage current, reduce signal crosstalk, and generate electrical signals of different intensities.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] This invention provides an image sensor, comprising:

[0007] Substrate;

[0008] A photodiode is disposed in the substrate, and the photodiode has a first recess.

[0009] A deep trench isolation structure is disposed in the substrate and located between adjacent photodiodes. The deep trench isolation structure includes a transparent graphene layer, which is bonded to the photodiode.

[0010] The photoelectric response region is formed by filling the first recess with a graphene layer, and the depth of the photoelectric response region first increases and then decreases along the width direction of the photoelectric response region.

[0011] In one embodiment of the present invention, the photoresponse region is located on the surface of the photodiode.

[0012] In one embodiment of the present invention, the deep trench isolation structure further includes:

[0013] A first silicon oxide layer, the first silicon oxide layer covering the transparent graphene layer within the deep trench isolation structure; and

[0014] An air region, which is located within the first silicon oxide layer.

[0015] In one embodiment of the present invention, the deep trench isolation structure further includes:

[0016] A first silicon oxide layer covers the transparent graphene layer within the deep trench isolation structure;

[0017] A high dielectric constant dielectric layer, wherein the high dielectric constant dielectric layer covers the first silicon oxide layer;

[0018] A second silicon oxide layer, the second silicon oxide layer covering the high dielectric constant dielectric layer; and

[0019] An air region, which is located within the second silicon oxide layer.

[0020] In one embodiment of the present invention, the image sensor further includes an optical control structure extending from the surface of the photodiode into the photodiode, the photoresponse region being located at the bottom of the optical control structure, and the optical control structure including a light-transmitting graphene layer, the light-transmitting graphene layer being bonded to the photodiode.

[0021] In one embodiment of the present invention, the optical control structure further includes a first silicon oxide layer, which covers the transparent graphene layer in the optical control structure.

[0022] In one embodiment of the present invention, the optical control structure further includes:

[0023] A first silicon oxide layer covers the transparent graphene layer in the optical control structure;

[0024] A high dielectric constant dielectric layer, wherein the high dielectric constant dielectric layer covers the first silicon oxide; and

[0025] A second silicon oxide layer covers the high dielectric constant dielectric layer.

[0026] This invention also provides a method for manufacturing an image sensor, comprising the following steps:

[0027] Provide a substrate;

[0028] A photodiode is formed in the substrate, and the substrate and the photodiode are simultaneously etched to form a deep trench in the substrate and a first recess in the photodiode.

[0029] A deep trench isolation structure is formed by filling the deep trench with a dielectric material, and the deep trench isolation structure is located between adjacent photodiodes. The deep trench isolation structure includes a transparent graphene layer, which is bonded to the photodiode.

[0030] A graphene layer is filled in the first recess to form a photoresponse region, and the depth of the photoresponse region first increases and then decreases along the width direction of the photoresponse region.

[0031] In one embodiment of the present invention, after forming the deep trench and the first recess, the manufacturing method includes the following steps:

[0032] A barrier layer is formed on the substrate, the barrier layer covering other areas on the substrate except for the deep trench and the first recess;

[0033] Graphene layers are deposited in the first recess and the deep trench, wherein the graphene layer in the first recess forms the photoelectric response region, and the graphene layer in the deep trench forms the light-transmitting graphene layer.

[0034] In one embodiment of the present invention, the manufacturing method includes the following steps:

[0035] While forming the deep trench and the first recess, the photodiode is simultaneously etched to form the second recess, and the first recess is located at the bottom of the second recess;

[0036] A barrier layer is formed on the substrate, the barrier layer covering the other areas on the substrate except for the deep trench and the second recess;

[0037] Graphene layers are deposited in the first recess, the second recess, and the deep trench, wherein the graphene layer in the first recess forms the photoelectric response region, and the graphene layers in the deep trench and the second recess form the light-transmitting graphene layer.

[0038] In summary, the image sensor and its fabrication method provided by this invention have the following unexpected effects: First, graphene has a small band gap and a high response rate to near-infrared light, while single-crystal silicon has very little response to near-infrared light above 700nm, especially above 1100nm. Using graphene and silicon substrates together can significantly improve the near-infrared responsivity of the image sensor device, thereby greatly improving the photoelectric conversion efficiency of the image sensor device. Second, by controlling the thickness of graphene, a nearly transparent graphene layer can be achieved. The visible light transmittance of graphene smaller than 1200Å can reach over 98%. Setting a transparent graphene layer on the deep trench isolation structure and optical control structure in the image sensor can significantly improve the near-infrared light response and photoelectric conversion efficiency of the image sensor without losing visible light, thus expanding the application range. Third, graphene has a high carrier mobility, and the carrier mobility of graphene (15000 cm⁻¹) is... 2 The carrier mobility ( / V·s) is much higher than that of silicon (1000 cm⁻¹). 2 The addition of a graphene layer enables rapid electron transport, allowing photons to be quickly converted into electrons within the photodiode of the image sensor. This avoids photon loss during photodiode propagation and improves the photoresponsivity and accuracy of the image sensor device. Fourth, the refractive index of graphene (n=1.7~4.39) is greater than that of silicon dioxide (n=1.45). The refractive index can be controlled by adjusting the thickness of the graphene layer. Adding a graphene layer to the image sensor increases the reflection and refraction of visible light and allows for the direct absorption of near-infrared light, which is then rapidly converted into electrons within the photodiode. This significantly reduces the thickness of the silicon substrate, enabling high photoelectric conversion efficiency image sensors with thinner silicon substrates. Fifth, graphene has high thermal conductivity (5300 W / m·K), which is much higher than that of monocrystalline silicon (157 W / m·K). Adding a graphene layer is beneficial for heat dissipation in image sensor devices and increases the lifespan of the devices. Sixth, graphene has stable physical and chemical properties and excellent mechanical properties. Adding graphene to image sensors can significantly improve the compressive or tensile strength of the devices, improve wafer warpage, and increase the external tensile and compressive forces on the wafer during the dicing and packaging process, thus avoiding device deformation and failure caused by dicing and tensile forces.

[0039] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of a structure forming a photodiode, a deep trench, and a first recess in one embodiment.

[0042] Figure 2 for Figure 1 A top view of the structural schematic diagram of the photodiode, deep trench, and first recess.

[0043] Figure 3 This is a schematic diagram of the structure in one embodiment where a graphene layer is formed.

[0044] Figure 4 This is a schematic diagram of a structure forming a photoelectric response region and a deep trench isolation structure in one embodiment.

[0045] Figure 5 This is a schematic diagram of the structure forming a grille in one embodiment.

[0046] Figure 6 This is a schematic diagram of the structure of an image sensor in one embodiment.

[0047] Figure 7 This is a schematic diagram of the image sensor structure in another embodiment.

[0048] Figure 8 This is a schematic diagram of the structure forming a photodiode, a deep trench, a first recess, and a second recess in another embodiment.

[0049] Figure 9 for Figure 8 A top view of the structural schematic diagram of the photodiode, deep trench, first recess, and second recess.

[0050] Figure 10 This is a schematic diagram of the structure in another embodiment where a graphene layer is formed.

[0051] Figure 11 This is a schematic diagram of the structure forming the photoelectric response region, optical control structure and deep trench isolation structure in another embodiment.

[0052] Figure 12 This is a schematic diagram of the structure forming the grille in another embodiment.

[0053] Figure 13 This is a schematic diagram of the image sensor structure in another embodiment.

[0054] Figure 14 This is a schematic diagram of the image sensor structure in another embodiment.

[0055] Label Explanation:

[0056] 101. Substrate; 102. Photodiode; 103. Deep trench isolation structure; 1031. Deep trench; 1032. Transparent graphene layer; 1033. First silicon oxide layer; 1034. Air region; 1035. High dielectric constant dielectric layer; 1036. Second silicon oxide layer; 104. Photoresponse region; 1041. First recess; 1051. Barrier layer; 1052. Graphene layer; 106. Grating; 107. Color filter; 108. Microlens; 109. Optical control structure; 1091. Second recess. Detailed Implementation

[0057] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0058] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0059] In this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used only for descriptive and distinguishing purposes and should not be construed as indicating or implying relative importance.

[0060] An image sensor includes a pixel array. Within this array, multiple photodiodes are arranged in an array, each forming a pixel unit. Multiple photodiodes together form the pixel array. When an image is focused onto the pixel array of the image sensor through an imaging lens, the photodiodes convert light signals from their surfaces into electrical signals. These electrical signals can then be quantized using an analog-to-digital converter, and the converted digital signal is read out.

[0061] Please see Figure 6 and Figure 7 As shown, in one embodiment of the present invention, the image sensor provided by this application includes a substrate 101, in which a photodiode 102 is disposed, and adjacent photodiodes 102 are isolated using a deep trench isolation structure 103. The deep trench isolation structure 103 includes a light-transmitting graphene layer 1032, and the light-transmitting graphene layer 1032 is attached to the photodiode 102. A first recess 1041 is disposed in the photodiode 102, and a graphene layer 1052 is filled in the first recess 1041 to form a photoresponse region 104. Along the width direction of the photoresponse region 104, the depth of the photoresponse region 104 first increases and then decreases. A grid 106 is also disposed on the deep trench isolation structure 103, and a color filter 107 and a microlens 108 are also disposed on the photodiode 102.

[0062] For details, please refer to Figure 1 As shown, in one embodiment of the present invention, the substrate 101 can be any suitable silicon-based semiconductor material, specifically, for example, silicon, silicon carbide (SiC), or silicon-on-insulator (SiInsulator). Furthermore, the material of the substrate 101 can also be silicon-on-insulator, silicon-germanium-on-insulator, silicon-germanium-on-insulator, or germanium-on-insulator. In this embodiment, the substrate 101 is, for example, a silicon substrate, which can be an undoped substrate or a doped substrate. In this embodiment, the substrate 101 is, for example, a p-type silicon substrate.

[0063] Please see Figure 1 As shown, in one embodiment of the present invention, a photodiode 102 is disposed in a substrate 101, which can convert optical signals into electrical signals. The photodiode 102 extends from the surface of the substrate 101 toward the bottom of the substrate 101, and the bottom of the photodiode 102 is at a predetermined distance from the bottom of the substrate 101. Specifically, ions can be implanted into the substrate 101 to form the photodiode 102. This application does not limit the type of ions implanted in the substrate 101, as long as the desired device is formed. Furthermore, during the formation of the photodiode 102, in order to ensure the quality and shape of the photodiode 102 formed after ion implantation, multiple ion implantations at different angles can be performed to form a photodiode 102 conforming to a predetermined pattern.

[0064] Please see Figures 1 to 4As shown, in one embodiment of the present invention, a deep trench isolation structure 103 is provided between adjacent photodiodes 102. The deep trench isolation structure 103 can isolate adjacent photodiodes 102 and avoid visible light crosstalk between adjacent photodiodes 102. A first recess 1041 is provided on the surface of the photodiode 102, and a graphene layer 1052 fills the first recess 1041 to form a photoresponse region 104. The interface between the graphene layer 1052 in the photoresponse region 104 and the silicon in the photodiode 102 will quickly respond and complete the photoelectric conversion after a photon touches it, and the graphene layer 1052 in the photoresponse region 104 can respond to near-infrared light.

[0065] Please see Figure 1 As shown, in one embodiment of the present invention, after forming the photodiode 102, the substrate 101 is first etched to form a deep trench 1031 and a first recess 1041. The substrate 101 can be etched twice to form the deep trench 1031 and the first recess 1041, respectively. Specifically, a photoresist layer (not shown) can be formed on the surface of the substrate 101, and a patterned photoresist layer (not shown) can be formed through processes such as exposure and development. This patterned photoresist layer defines the location of the deep trench 1031. Then, using this patterned photoresist layer as a mask, a portion of the substrate 101 located under the patterned photoresist layer is quantitatively removed using etching methods such as dry etching, wet etching, or a combination of dry and wet etching to form the deep trench 1031. Afterwards, another photoresist layer (not shown) is repeatedly formed on the surface of the substrate 101, and another patterned photoresist layer (not shown) is formed through processes such as exposure and development. This patterned photoresist layer defines the location of the first recess 1041. Using the patterned photoresist layer as a mask, a portion of the substrate 101 located under the patterned photoresist layer is quantitatively removed using etching methods such as dry etching, wet etching, or a combination of dry and wet etching to obtain the first recess 1041. This application does not limit the formation order of the deep trench 1031 and the first recess 1041. In other embodiments, the substrate 101 may be etched first to form the first recess 1041, and then the substrate 101 may be etched to form the deep trench 1031.

[0066] Please see Figure 1 As shown, in one embodiment of the present invention, a deep trench 1031 is disposed between adjacent photodiodes 102, and the depth of the deep trench 1031 is greater than the depth of the photodiode 102, so that the subsequently formed deep trench isolation structure 103 can effectively isolate adjacent photodiodes 102. A first recess 1041 is located on the surface of the photodiode 102. The first recess 1041 is formed in the photodiode 102 by etching away a portion of the already formed photodiode 102. The maximum depth of the first recess 1041 is greater than one-quarter of the depth of the photodiode 102. Please refer to... Figure 2 As shown, in the width direction of the first recess 1041, the depth of the first recess 1041 first increases and then decreases, that is, the middle depth of the formed first recess 1041 is greater than the edge depth. The width direction of the first recess 1041 is, for example, as follows: Figure 2 The cross-sections along lines A-A' and B-B' represent the width direction of the first recess 1041. All cross-sectional views in this application are located along the width direction of the first recess 1041. Furthermore, the radial dimension of the first recess 1041 is less than one-quarter of the width of the photodiode 102. In this embodiment, the cross-section of the first recess 1041 is, for example, semi-elliptical.

[0067] Please see Figures 1 to 3 As shown, in one embodiment of the present invention, after forming the deep trench 1031 and the first recess 1041, a dielectric material is filled in the deep trench 1031 to form a deep trench isolation structure 103, and a dielectric material is filled in the first recess 1041 to form a photoelectric response region 104. In this application, the dielectric material filled into the first recess 1041 is, for example, a graphene layer 1052. The dielectric material filled on the inner wall of the deep trench 1031 in contact with the photodiode 102 is also a graphene layer 1052. Therefore, after forming the deep trench 1031 and the first recess 1041, the graphene layer 1052 can be filled into the deep trench 1031 and the first recess 1041 simultaneously. Specifically, a barrier layer 1051 is first formed on the substrate 101. The barrier layer 1051 covers the areas of the substrate 101 other than the deep trench 1031 and the first recess 1041. This ensures that there is no excess graphene on the substrate 101 other than the deep trench 1031 and the first recess 1041, so as not to affect the transmission of visible light, and further ensures the insulation of the image sensor device subsequently formed. After forming the barrier layer 1051, a graphene layer 1052 is simultaneously deposited on the inner wall of the deep trench 1031 and the first recess 1041. For example, a graphene layer 1052 can be deposited on the inner wall of the deep trench 1031 using methods such as chemical vapor deposition (CVD) or molecular beam epitaxy. Compared to the depth of the deep trench 1031, the depth and width of the first recess 1041 are smaller. Therefore, when a graphene layer 1052 is deposited on the inner wall of the deep trench 1031, the graphene layer 1052 can fill the first recess 1041 to form a photoelectric response region 104.

[0068] Please see Figure 3 and Figure 4As shown, in one embodiment of the present invention, when graphene layers 1052 are simultaneously filled into the deep trench 1031 and the first recess 1041, the thickness of the graphene layer 1052 deposited in the deep trench 1031 is controlled to be less than 1200 Å, forming a light-transmitting graphene layer 1032. The thickness of the light-transmitting graphene layer 1032 is specifically, for example, 800 Å, 900 Å, 1000 Å, or 1100 Å, or it can be 850 Å, 950 Å, 1050 Å, or 1150 Å. The light-transmitting graphene layer 1032 covers the inner wall of the deep trench 1031, including the sidewalls and bottom wall of the deep trench 1031. After simultaneously filling the deep trench 1031 and the first recess 1041 with graphene layers 1052, the graphene layer 1052 in the first recess 1041 forms a photoelectric response region 104. In this application, the depth of the photoresponse region 104 first increases and then decreases in the width direction, and the photoresponse region 104 is, for example, ellipsoidally shaped. In this application, to ensure that the graphene layer 1052 can completely fill the first recess 1041, the maximum depth of the first recess 1041 can be set to 14000 Å, 15000 Å, or 16000 Å, etc. The width direction of the photoresponse region 104 is the same as the width direction of the first recess 1041.

[0069] Please see Figure 4 As shown, in one embodiment of the present invention, the deep trench isolation structure 103 includes a transparent graphene layer 1032, a first silicon oxide layer 1033, and an air region 1034. The first silicon oxide layer 1033 covers the transparent graphene layer 1032, and also covers the graphene layers 1052 on the bottom and sidewalls of the deep trench 1031. Specifically, after forming the transparent graphene layer 1032, the first silicon oxide layer 1033 can be deposited on the transparent graphene layer 1032. When the first silicon oxide layer 1033 is deposited until the opening of the deep trench 1031 is nearly closed, the top layer of the first silicon oxide layer 1033 closes because the remaining unfilled opening of the deep trench 1031 is relatively small, and the unfilled area in the middle of the deep trench 1031 forms an air region 1034.

[0070] Please see Figure 7As shown, in another embodiment of the present invention, the deep trench isolation structure 103 includes a transparent graphene layer 1032, a first silicon oxide layer 1033, a high dielectric constant dielectric layer 1035, a second silicon oxide layer 1036, and an air region 1034. The first silicon oxide layer 1033 covers the transparent graphene layer 1032 within the deep trench 1031, and also covers the graphene layers 1052 on the bottom and sidewalls of the deep trench 1031. The high dielectric constant dielectric layer 1035 covers the first silicon oxide layer 1033 within the deep trench 1031, and the second silicon oxide layer 1036 covers the high dielectric constant dielectric layer 1035 within the deep trench 1031. Specifically, after forming the transparent graphene layer 1032, the first silicon oxide layer 1033, the high dielectric constant dielectric layer 1035, and the second silicon oxide layer 1036 can be sequentially deposited on the transparent graphene layer 1032. Furthermore, when the second silicon oxide layer 1036 is deposited until the opening of the deep trench 1031 is nearly closed, the second silicon oxide layer 1036 at the top layer closes because the opening of the remaining unfilled deep trench 1031 is small, and the unfilled area in the middle of the deep trench 1031 forms an air region 1034.

[0071] Please see Figure 4 and Figure 7 As shown, in this invention, the high dielectric constant dielectric layer 1035 is, for example, a composite dielectric layer such as hafnium oxide (HfO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), or a linear combination of HfO2 and SiO2. Furthermore, this invention does not limit the deposition method of the silicon oxide layer and the high dielectric constant dielectric layer 1035; the specific method depends on the materials and shape of the silicon oxide layer and the high dielectric constant dielectric layer 1035.

[0072] Please see Figure 5 and Figure 7 As shown, in one embodiment of the present invention, a grid 106 is provided on the deep trench isolation structure 103, a color filter 107 is provided on the photodiode 102, and a microlens 108 is also provided on the color filter 107. The grid 106 is located on the deep trench isolation structure 103, and the edge of the grid 106 is aligned with the deep trench isolation structure 103. The color filter 107 is provided on the photodiode 102, and the color filter 107 covers the photodiode 102. The microlens 108 is provided on the color filter 107.

[0073] Please see Figure 5 and Figure 7As shown, in one embodiment of the present invention, after forming the deep trench isolation structure 103, a silicon layer (not shown) is deposited on the substrate 101 as the material layer of the grille 106. Then, a patterned photoresist layer (not shown) is formed on the material layer, and using the patterned photoresist layer as a mask, the material layer is etched, leaving only the material layer on the deep trench isolation structure 103. The material layer on the deep trench isolation structure 103 forms the grille 106. In other embodiments, the material layer of the grille 106 may include a stacked high-dielectric-constant material layer, an aluminum metal layer, and a titanium nitride layer. The high-dielectric-constant material layer is, for example, a tantalum pentoxide layer. The high-dielectric-constant material layer can effectively isolate adjacent photoresponse regions 104, the aluminum metal layer provides good light-shielding, and the titanium nitride layer not only has high stability but also high reflectivity and anti-reflection properties, reflecting incident light at the grille 106 and making the grille 106 more stable. Therefore, the formed grille 106 not only provides light-shielding but also reduces dark current generation.

[0074] Please see Figure 6 and Figure 7 As shown, in one embodiment of the present invention, a color filter 107 is located on a photodiode 102, and a color filter array is composed of multiple colors of color filters. In this embodiment, the color filter 107 may include at least three primary color filters, such as a red filter, a green filter, and a blue filter, and the three color filters 107 can be arranged in any suitable combination. For example, the red filter, green filter, and blue filter can be arranged alternately. A transparent filter can also be provided, and the red filter, green filter, blue filter, and transparent filter can be arranged alternately. After forming the grid 106, the color filter 107 is formed between adjacent grids 106. The color filter 107 can be a polymer material, such as a negative photoresist based on an acrylic polymer, and may contain colored dyes. After forming the grid 106, the color filter 107 can be directly vacuum-deposited between the grids 106. When light passes through the color filter 107, its color can be changed, maintaining a high transmittance of a certain wavelength (color), thereby enhancing the photoelectric conversion effect.

[0075] Please see Figure 5 and Figure 7 As shown, in one embodiment of the present invention, the material of the microlens 108 structure can be resin. After forming the color filter 107, the microlens 108 structure can be formed on the color filter 107 by a reflow soldering process. The microlens 108 structure is disposed on the color filter 107. The refractive index of the microlens 108 structure can be appropriately varied according to the optical requirements of the image sensor. The microlens 108 structure can focus light onto the photodiode 102, and the curvature of the surface of the microlens 108 structure can be changed according to the light focusing requirements.

[0076] Please see Figure 6 and Figure 7 As shown, the image sensor provided by this invention has a high response rate to near-infrared light due to the small band gap of graphene. When light shines on the photodiode 102, the interface between the graphene layer 1052 in the photoresponse region 104 and the silicon in the photodiode 102 will quickly respond and complete photoelectric conversion upon photon contact. When the light passes through the shallower areas on both sides of the photoresponse region 104, visible light and a small amount of unresponsive near-infrared light will pass through the graphene layer 1052 in the photoresponse region 104 and be refracted. After refraction, the light reaches the transparent graphene layer 1032 on the isolation surface of the deep trench 1031. The visible light continues to be reflected and refracted to reach the photodiode 102 for photoelectric conversion, while the near-infrared light gradually responds through the interface between the transparent graphene layer 1032 and silicon. At this time, the deep trench isolation structure 103 can prevent crosstalk between visible light sources and increase the reflection and refraction of visible light, ensuring that the image sensor responds quickly to near-infrared light while also achieving accurate response to visible light.

[0077] Please see Figure 8 and Figure 14 As shown, in another embodiment of the present invention, the image sensor provided in this application includes a substrate 101, in which a photodiode 102 is disposed, and adjacent photodiodes 102 are isolated using a deep trench isolation structure 103. The deep trench isolation structure 103 includes a light-transmitting graphene layer 1032, and the light-transmitting graphene layer 1032 is attached to the photodiode 102. A first recess 1041 and a second recess 1091 are also disposed in the photodiode 102, wherein the first recess 1041 is located at the bottom of the second recess 1091, and the volume of the first recess 1041 is smaller than the volume of the second recess 1091. A graphene layer 1052 is filled in the first recess 1041 to form a photoresponse region 104. Please refer to... Figure 9 As shown, the depth of the photoresponse region 104 first increases and then decreases along the width direction of the photoresponse region 104. A transparent graphene layer 1032 and a silicon oxide layer, etc., are filled in the second recess 1091 to form an optical control structure 109. A grid 106 is also provided on the deep trench isolation structure 103, and a color filter 107 and a microlens 108 are also provided on the photodiode 102.

[0078] For details, please refer to Figure 8As shown, in another embodiment of the present invention, the substrate 101 can be any suitable silicon-based semiconductor material, specifically, for example, silicon, silicon carbide (SiC), or silicon-on-insulator (SiInsulator). Furthermore, the material of the substrate 101 can also be silicon-on-insulator, silicon-on-insulator, silicon-on-insulator, or germanium-on-insulator. In this embodiment, the substrate 101 is, for example, a silicon substrate, which can be an undoped substrate or a doped substrate. In this embodiment, the substrate 101 is, for example, a P-type silicon substrate.

[0079] Please see Figure 8 As shown, in another embodiment of the present invention, a photodiode 102 is disposed in the substrate 101, which can convert optical signals into electrical signals. The photodiode 102 extends from the surface of the substrate 101 toward the bottom of the substrate 101, and the bottom of the photodiode 102 is at a predetermined distance from the bottom of the substrate 101. Specifically, ions can be implanted into the substrate 101 to form the photodiode 102. This application does not limit the type of ions implanted in the substrate 101, as long as the desired device is formed. In this embodiment, the substrate 101 is P-type, so the ions implanted in the substrate 101 are, for example, N-type ions. The implanted ions can specifically be ions with five valence electrons, such as phosphorus ions or arsenic ions. When phosphorus ions replace silicon atoms, they provide a negatively charged electron to the valence band of the crystal, thereby forming an N-type photodiode. In other embodiments, when the substrate 101 is N-type, P-type ions can also be implanted into the substrate 101 to form a P-type photodiode. In the process of forming the photodiode 102, in order to ensure the quality and shape of the photodiode 102 formed after ion implantation, ion implantation at different angles can be performed multiple times to form a photodiode 102 that conforms to the preset pattern.

[0080] Please see Figure 8As shown, in another embodiment of the present invention, a deep trench isolation structure 103 is provided between adjacent photodiodes 102. The deep trench isolation structure 103 can isolate adjacent photodiodes 102 and avoid visible light crosstalk between adjacent photodiodes 102. A second recess 1091 is provided on the surface of the photodiode 102, and a first recess 1041 is provided at the bottom of the second recess 1091. A graphene layer 1052 fills the first recess 1041 to form a photoresponse region 104. A transparent graphene layer 1032 and a silicon oxide layer or other dielectric layer are filled in the second recess 1091 to form an optical control structure 109. When light enters the optical control structure 109, some photons are trapped within it, undergoing continuous reflection and refraction. The transparent graphene layer 1032 in the optical control structure 109 enables a rapid near-infrared light response in this region. Since the refractive index of graphene is higher than that of silicon oxide, it is equivalent to adding a lens to the photodiode 102, further increasing the optical path of visible light and achieving a rapid and precise response to both near-infrared and visible light. The thickness of the graphene layer 1052 in the photoresponse region 104 can be adjusted as needed to ensure a complete response to near-infrared light.

[0081] Please see Figure 8 As shown, in another embodiment of the present invention, after forming the photodiode 102, the substrate 101 is first etched to form a deep trench 1031, a second recess 1091, and a first recess 1041. The substrate 101 can be etched three times to form the deep trench 1031, the second recess 1091, and the first recess 1041, respectively. Specifically, a photoresist layer (not shown in the figure) can be formed on the surface of the substrate 101, and a patterned photoresist layer (not shown in the figure) can be formed through processes such as exposure and development. This patterned photoresist layer defines the position of the deep trench 1031. Then, using this patterned photoresist layer as a mask, a portion of the substrate 101 located under the patterned photoresist layer is quantitatively removed using etching methods such as dry etching, wet etching, or a combination of dry and wet etching to form the deep trench 1031. The etching steps are then repeated to form the second recess 1091 in the photodiode 102. The etching process is repeated to etch the photodiode 102 at the bottom of the second recess 1091, forming the first recess 1041 at the bottom of the second recess 1091. This application does not limit the formation order of the deep trench 1031, the second recess 1091, and the first recess 1041. In some other embodiments, the substrate 101 may be etched first to form the second recess 1091 and the first recess 1041, and then the substrate 101 may be etched to form the deep trench 1031.

[0082] Please see Figure 8As shown, in another embodiment of the present invention, a deep trench 1031 is disposed between adjacent photodiodes 102, and the depth of the deep trench 1031 is greater than the depth of the photodiodes 102, so that the subsequently formed deep trench isolation structure 103 can effectively isolate adjacent photodiodes 102. A second recess 1091 is located on the surface of the photodiode 102, and a first recess 1041 is located at the bottom of the second recess 1091. The second recess 1091 and the first recess 1041 are formed in the photodiode 102 by etching away a portion of the already formed photodiode 102. The maximum depth of the second recess 1091 is less than one-third of the depth of the photodiode 102, and the depth of the second recess 1091 first increases and then decreases in the width direction, meaning that the middle depth of the formed second recess 1091 is greater than the edge depth. Simultaneously, the radial dimension of the second recess 1091 is less than one-third of the width of the photodiode 102. The first recess 1041 is located at the bottom of the second recess 1091. The first recess 1041 is formed in the photodiode 102 at the bottom of the second recess 1091 by etching away a portion of the already formed photodiode 102. The maximum depth of the first recess 1041 is greater than one-quarter of the depth of the photodiode 102, and the depth of the first recess 1041 first increases and then decreases in the width direction, meaning the middle depth of the formed first recess 1041 is greater than the edge depth. Simultaneously, the radial dimension of the first recess 1041 is less than one-quarter of the width of the photodiode 102. The size of the first recess 1041 can be adjusted according to the amount of infrared light to be absorbed, so that the subsequently formed photoresponse region 104 can absorb all infrared light. In this embodiment, the cross-sections of the second recess 1091 and the first recess 1041 are, for example, semi-elliptical.

[0083] Please see Figure 8 and Figure 10As shown, in another embodiment of the present invention, after forming the deep trench 1031, the second recess 1091, and the first recess 1041, a medium is filled in the deep trench 1031 to form a deep trench isolation structure 103, and a medium is filled in the second recess 1091 to form an optical control structure 109. A medium is filled in the first recess 1041 to form a photoelectric response region 104. In this application, the medium filled in the first recess 1041 is, for example, a graphene layer 1052. The medium filled on the inner wall of the second recess 1091 in contact with the photodiode 102 and on the inner wall of the deep trench 1031 in contact with the photodiode 102 is also a graphene layer 1052. Therefore, after forming the deep trench 1031, the second recess 1091, and the first recess 1041, the graphene layer 1052 can be filled in the deep trench 1031, the second recess 1091, and the first recess 1041 simultaneously. Specifically, a barrier layer 1051 is first formed on the substrate 101. The barrier layer 1051 covers all areas of the substrate 101 except for the deep trench 1031, the second recess 1091, and the first recess 1041. This ensures that there is no excess graphene in the areas of the substrate 101 except for the deep trench 1031, the second recess 1091, and the first recess 1041, so as not to affect the transmission of visible light, and further ensures the insulation of the image sensor subsequently formed. After forming the barrier layer 1051, a graphene layer 1052 is simultaneously deposited on the inner wall of the deep trench 1031, the inner wall of the second recess 1091, and the first recess 1041. For example, a chemical vapor deposition (CVD) or molecular beam epitaxy method can be used to deposit a graphene layer 1052 on the inner wall of the deep trench 1031 and the inner wall of the second recess 1091. Compared to the depth of the deep trench 1031 and the second recess 1091, the depth and width of the first recess 1041 are smaller. Therefore, when a graphene layer 1052 is deposited on the inner wall of the deep trench 1031 and the inner wall of the second recess 1091, the graphene layer 1052 can fill the first recess 1041 to form a photoelectric response region 104.

[0084] Please see Figure 10As shown, in another embodiment of the present invention, when graphene layers 1052 are simultaneously filled in the deep trench 1031, the second recess 1091, and the first recess 1041, the thickness of the graphene layers 1052 deposited in the deep trench 1031 and the second recess 1091 is controlled to be less than 1200 Å, forming a translucent graphene layer 1032. The thickness of the translucent graphene layer 1032 is specifically, for example, 800 Å, 900 Å, 1000 Å, or 1100 Å, or it can be 850 Å, 950 Å, 1050 Å, or 1150 Å. The translucent graphene layer 1032 covers the inner walls of the deep trench 1031 and the second recess 1091, including the sidewalls and bottom wall of the deep trench 1031, and the inner wall of the second recess 1091. After the graphene layer 1052 is simultaneously filled into the deep trench 1031, the second recess 1091, and the first recess 1041, the graphene layer 1052 in the first recess 1041 forms a photoresponse region 104. In this application, the depth of the photoresponse region 104 first increases and then decreases in the width direction, and the photoresponse region 104 is, for example, ellipsoidally shaped. In this application, to ensure that the graphene layer 1052 can completely fill the first recess 1041, the maximum depth of the first recess 1041 can be set to 14000 Å, 15000 Å, or 16000 Å, etc.

[0085] Please see Figure 11 As shown, in another embodiment of the present invention, the deep trench isolation structure 103 includes a transparent graphene layer 1032, a first silicon oxide layer 1033, and an air region 1034. The first silicon oxide layer 1033 covers the transparent graphene layer 1032, and also covers the graphene layers 1052 on the bottom and sidewalls of the deep trench 1031. The optical control structure 109 includes a transparent graphene layer 1032 and a first silicon oxide layer 1033, wherein the first silicon oxide layer 1033 in the second recess 1091 covers the transparent graphene layer 1032 within the second recess 1091 and the photoelectric response region 104 at the bottom of the second recess 1091. Specifically, after forming a transparent graphene layer 1032 in the deep trench 1031 and the second recess 1091, a first silicon oxide layer 1033 is simultaneously deposited on the transparent graphene layer 1032 in the deep trench 1031 and the second recess 1091. When the first silicon oxide layer 1033 is deposited in the deep trench 1031 until the opening of the deep trench 1031 is nearly closed, the top layer of the first silicon oxide layer 1033 closes because the opening of the remaining unfilled deep trench 1031 is relatively small, and the unfilled area in the middle of the deep trench 1031 forms an air region 1034. The opening of the second recess 1091 is relatively large, and the first silicon oxide layer 1033 will fill the second recess 1091.

[0086] Please see Figure 14As shown, in another embodiment of the present invention, the deep trench isolation structure 103 includes a transparent graphene layer 1032, a first silicon oxide layer 1033, a high dielectric constant dielectric layer 1035, a second silicon oxide layer 1036, and an air region 1034. The first silicon oxide layer 1033 in the deep trench 1031 covers the transparent graphene layer 1032 within the deep trench 1031, and also covers the graphene layers 1052 on the bottom and sidewalls of the deep trench 1031. The high dielectric constant dielectric layer 1035 in the deep trench 1031 covers the first silicon oxide layer 1033 within the deep trench 1031, and the second silicon oxide layer 1036 in the deep trench 1031 covers the high dielectric constant dielectric layer 1035 within the deep trench 1031. The optical control structure 109 includes a transparent graphene layer 1032, a first silicon oxide layer 1033, a high-dielectric-constant dielectric layer 1035, and a second silicon oxide layer 1036. Specifically, the first silicon oxide layer 1033 in the second recess 1091 covers the transparent graphene layer 1032 within the second recess 1091 and the photoelectric response region 104 at the bottom of the second recess 1091; the high-dielectric-constant dielectric layer 1035 in the second recess 1091 covers the first silicon oxide layer 1033 in the second recess 1091; and the second silicon oxide layer 1036 in the second recess 1091 covers the high-dielectric-constant dielectric layer 1035 in the second recess 1091. Specifically, after forming the transparent graphene layer 1032 in the deep trench 1031 and the second recess 1091, the first silicon oxide layer 1033, the high-dielectric-constant dielectric layer 1035, and the second silicon oxide layer 1036 are sequentially deposited on the transparent graphene layer 1032. Furthermore, in the deep trench 1031, when the second silicon oxide layer 1036 is deposited until the opening of the deep trench 1031 is close to closing, the second silicon oxide layer 1036 at the top layer closes because the opening of the remaining unfilled deep trench 1031 is small, and the unfilled area in the middle of the deep trench 1031 forms an air area 1034.

[0087] Please see Figure 11 and Figure 14 As shown, in this invention, the high dielectric constant dielectric layer 1035 is, for example, a composite dielectric layer such as hafnium oxide (HfO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), or a linear combination of HfO2 and SiO2. Furthermore, this invention does not limit the deposition method of the silicon oxide layer and the high dielectric constant dielectric layer 1035; the specific method depends on the materials and shape of the silicon oxide layer and the high dielectric constant dielectric layer 1035.

[0088] Please see Figure 12 and Figure 14As shown, in another embodiment of the present invention, a grid 106 is provided on the deep trench isolation structure 103, a color filter 107 is provided on the photodiode 102, and a microlens 108 is also provided on the color filter 107. The grid 106 is located on the deep trench isolation structure 103, and the edge of the grid 106 is aligned with the deep trench isolation structure 103. The color filter 107 is provided on the photodiode 102, and the color filter 107 covers the optical control structure 109. The microlens 108 is provided on the color filter 107.

[0089] Please see Figure 12 and Figure 14 As shown, in another embodiment of the present invention, after forming the deep trench isolation structure 103, a silicon layer (not shown) is deposited on the substrate 101 as the material layer of the grille 106. Then, a patterned photoresist layer (not shown) is formed on the material layer, and using the patterned photoresist layer as a mask, the material layer is etched, leaving only the material layer on the deep trench isolation structure 103. The material layer on the deep trench isolation structure 103 forms the grille 106. In other embodiments, the material layer of the grille 106 may include a stacked high dielectric constant material layer, an aluminum metal layer, and a titanium nitride layer. The high dielectric constant material layer is, for example, a tantalum pentoxide layer. The high dielectric constant material layer can effectively isolate adjacent photoresponse regions 104, the aluminum metal layer provides good light-shielding, and the titanium nitride layer not only has high stability but also high reflectivity and anti-reflection properties, reflecting incident light at the grille 106 and making the grille 106 more stable. Therefore, the formed grille 106 not only has a light-shielding function but also reduces the generation of dark current.

[0090] Please see Figure 13 and Figure 14 As shown, in another embodiment of the present invention, a color filter 107 is located on a photodiode 102, and a color filter array is composed of multiple colors of color filters. In this embodiment, the color filter 107 may include at least three primary color filters 107, such as a red filter, a green filter, and a blue filter, and the three color filters 107 can be arranged in any suitable combination. For example, the red filter, green filter, and blue filter can be arranged alternately. A transparent filter can also be provided, and the red filter, green filter, blue filter, and transparent filter can be arranged alternately. After forming the grid 106, the color filter 107 is formed between adjacent grids 106. The color filter 107 can be a polymer material, such as a negative photoresist based on an acrylic polymer, and may contain colored dyes. After forming the grid 106, the color filter 107 can be directly vacuum-deposited between the grids 106. When light passes through the color filter 107, its color can be changed, maintaining a high transmittance of a certain wavelength (color), thereby enhancing the photoelectric conversion effect.

[0091] Please see Figure 13 and Figure 14 As shown, in another embodiment of the present invention, the material of the microlens 108 structure can be resin. After the color filter 107 is formed, the microlens 108 structure can be formed on the color filter 107 by a reflow soldering process. The microlens 108 structure is disposed on the color filter 107. The refractive index of the microlens 108 structure can be appropriately varied according to the optical requirements of the image sensor. The microlens 108 structure can focus light onto the photodiode 102, and the curvature of the surface of the microlens 108 structure can be changed according to the light focusing requirements.

[0092] Please see Figure 13 and Figure 14 As shown, in another embodiment of the present invention, when light passes through the microlens 108, it enters the photodiode 102 perpendicularly. Since silicon-based image sensors have very little response to near-infrared light, filling the photoresponse region 104 with graphene ensures complete response to near-infrared light. Furthermore, the size and depth of the photoresponse region 104 can be adjusted according to the size of the photodiode 102 region and the size of the optical control structure 109 to ensure complete absorption of near-infrared light and achieve photoelectric conversion. Secondly, some photons are trapped within the optical control structure 109, resulting in continuous reflection and refraction. By controlling the deposition angle and filling the sidewalls of the optical control structure 109 with a transparent graphene layer 1032, a rapid response to near-infrared light in this region can be achieved. Furthermore, since the refractive index of graphene is higher than that of silicon oxide, it is equivalent to adding a lens layer within the photodiode 102, further increasing the optical path of visible light and achieving a rapid and accurate response to both near-infrared and visible light. Furthermore, by incorporating a transparent graphene layer 1032, a silicon oxide layer, and a high-dielectric-constant dielectric layer 1035 within the deep trench 1031, visible light and some near-infrared light can pass through the light stripe modulation structure to achieve multiple responses and complete photoelectric conversion. Simultaneously, the intermediate medium in the deep trench 1031 is air, and the graphene layer 1052 is located between silicon and silicon dioxide, constructing a silicon / graphene surface. This increases the overall refractive index, making total internal reflection easier and ensuring all photons are completely reflected into the photodiode 102 for precise response. If some near-infrared light remains after total internal reflection, the photoelectric response region 104, filled with graphene, will immediately absorb the photons upon contact. The silicon-graphene interface will then immediately respond to the near-infrared light, ensuring all photons complete photoelectric conversion. This significantly improves the photoelectric conversion efficiency of the image sensor device and expands its application scenarios.

[0093] In summary, the image sensor provided by this invention includes a substrate in which a photodiode is disposed. Adjacent photodiodes are isolated using a deep trench isolation structure, which includes a transparent graphene layer bonded to the photodiode. A photoresponse region is also disposed within the photodiode, and the depth of the photoresponse region first increases and then decreases along its width. An optical control structure may also be disposed within the photodiode, located on the photoresponse region. A grid is further disposed on the deep trench isolation structure, and a color filter and a microlens are also disposed on the photodiode.

[0094] In summary, the image sensor and its fabrication method provided by this invention have the following unexpected effects: First, graphene has a small band gap and a high response rate to near-infrared light, while single-crystal silicon has very little response to near-infrared light above 700nm, especially above 1100nm. Using graphene and silicon substrates together can significantly improve the near-infrared responsivity of the image sensor device, thereby greatly improving the photoelectric conversion efficiency of the image sensor device. Second, by controlling the thickness of graphene, a nearly transparent graphene layer can be achieved. The visible light transmittance of graphene smaller than 1200Å can reach over 98%. Setting a transparent graphene layer on the deep trench isolation structure and optical control structure in the image sensor can significantly improve the near-infrared light response and photoelectric conversion efficiency of the image sensor without losing visible light, thus expanding the application range. Third, graphene has a high carrier mobility, and the carrier mobility of graphene (15000 cm⁻¹) is... 2 The carrier mobility ( / V·s) is much higher than that of silicon (1000 cm⁻¹). 2The addition of a graphene layer enables rapid electron transport, allowing photons to be quickly converted into electrons within the photodiode of the image sensor. This avoids photon loss during photodiode propagation and improves the photoresponsivity and accuracy of the image sensor device. Fourth, the refractive index of graphene (n=1.7~4.39) is greater than that of silicon dioxide (n=1.45). The refractive index can be controlled by adjusting the thickness of the graphene layer. Adding a graphene layer to the image sensor increases the reflection and refraction of visible light and allows for the direct absorption of near-infrared light, which is then rapidly converted into electrons within the photodiode. This significantly reduces the thickness of the silicon substrate, enabling high photoelectric conversion efficiency image sensors with thinner silicon substrates. Fifth, graphene has high thermal conductivity (5300 W / m·K), which is much higher than that of monocrystalline silicon (157 W / m·K). Adding a graphene layer is beneficial for heat dissipation in image sensor devices and increases the lifespan of the devices. Sixth, graphene has stable physical and chemical properties and excellent mechanical properties. Adding graphene to image sensors can significantly improve the compressive or tensile strength of the devices, improve wafer warpage, and increase the external tensile and compressive forces on the wafer during the dicing and packaging process, thus avoiding device deformation and failure caused by dicing and tensile forces.

[0095] The embodiments of the present invention disclosed above are merely illustrative of the invention. The embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An image sensor, characterized in that, At least including: Substrate; A photodiode is disposed in the substrate, and the photodiode has a first recess. A deep trench isolation structure is disposed in the substrate and located between adjacent photodiodes. The deep trench isolation structure includes a light-transmitting graphene layer, which is bonded to the photodiode. The photoelectric response region is formed by filling the first recess with a graphene layer, and the depth of the photoelectric response region first increases and then decreases along the width direction of the photoelectric response region; as well as An optical control structure extends from the surface of the photodiode into the photodiode, the photoresponse region is located at the bottom of the optical control structure, and the optical control structure includes a light-transmitting graphene layer that is bonded to the photodiode.

2. The image sensor according to claim 1, characterized in that, The photoresponse region is located on the surface of the photodiode.

3. The image sensor according to claim 1, characterized in that, The deep trench isolation structure also includes: A first silicon oxide layer, the first silicon oxide layer covering the transparent graphene layer within the deep trench isolation structure; and An air region, which is located within the first silicon oxide layer.

4. The image sensor according to claim 1, characterized in that, The deep trench isolation structure also includes: A first silicon oxide layer covers the transparent graphene layer within the deep trench isolation structure; A high dielectric constant dielectric layer, wherein the high dielectric constant dielectric layer covers the first silicon oxide layer; A second silicon oxide layer, the second silicon oxide layer covering the high dielectric constant dielectric layer; and An air region, which is located within the second silicon oxide layer.

5. The image sensor according to claim 1, characterized in that, The optical control structure further includes a first silicon oxide layer, which covers the transparent graphene layer in the optical control structure.

6. The image sensor according to claim 1, characterized in that, The optical control structure also includes: A first silicon oxide layer covers the transparent graphene layer in the optical control structure; A high dielectric constant dielectric layer, wherein the high dielectric constant dielectric layer covers the first silicon oxide; and A second silicon oxide layer covers the high dielectric constant dielectric layer.

7. A method for manufacturing an image sensor, characterized in that, Includes the following steps: Provide a substrate; A photodiode is formed in the substrate, and the substrate and the photodiode are simultaneously etched to form a deep trench in the substrate and a first recess in the photodiode. A deep trench is formed by filling the deep trench with a dielectric material, and the deep trench isolating structure is located between adjacent photodiodes. The deep trench isolating structure includes a light-transmitting graphene layer, and the light-transmitting graphene layer is bonded to the photodiode. as well as A graphene layer is filled in the first recess to form a photoresponse region, and the depth of the photoresponse region first increases and then decreases along the width direction of the photoresponse region; An optical control structure is formed, which extends from the surface of the photodiode into the photodiode. The photoresponse region is located at the bottom of the optical control structure. The optical control structure includes a light-transmitting graphene layer, which is attached to the photodiode.

8. The method for manufacturing an image sensor according to claim 7, characterized in that, After forming the deep trench and the first recess, the manufacturing method includes the following steps: A barrier layer is formed on the substrate, the barrier layer covering other areas on the substrate except for the deep trench and the first recess; Graphene layers are deposited in the first recess and the deep trench, wherein the graphene layer in the first recess forms the photoelectric response region, and the graphene layer in the deep trench forms the light-transmitting graphene layer.

9. The method for manufacturing an image sensor according to claim 7, characterized in that, The manufacturing method includes the following steps: While forming the deep trench and the first recess, the photodiode is simultaneously etched to form the second recess, and the first recess is located at the bottom of the second recess; A barrier layer is formed on the substrate, the barrier layer covering the other areas on the substrate except for the deep trench and the second recess; Graphene layers are deposited in the first recess, the second recess, and the deep trench, wherein the graphene layer in the first recess forms the photoelectric response region, and the graphene layers in the deep trench and the second recess form the light-transmitting graphene layer.

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