Image sensor and manufacturing method thereof, imaging apparatus, and terminal device

Abstract

An image sensor (20) comprises a pixel array having a plurality of basic units, the basic unit comprising a first pixel (111), a second pixel (112) and a third pixel (113), the first pixel (111) being a short-wave band light pixel, the second pixel (112) being a middle-wave band light pixel; the pixel array comprises a color filter layer (120), a first substrate layer (130), a medium layer (140) and a second substrate layer (150) in a vertical direction; a first recess (137) extending to the first substrate layer (130) and corresponding to the first pixel (111) and a second recess (138) corresponding to the second pixel (112) are formed on the front surface of the first substrate layer (130), and the depth of the first recess (137) is greater than the depth of the second recess (138). The image sensor can improve the accuracy of color image imaging.

Description

Technical Field

[0001] This application relates to the field of image sensor technology, and more specifically, to an image sensor and its manufacturing method, as well as an imaging device and terminal equipment using the image sensor. Background Technology

[0002] Complementary Metal Oxide Semiconductor (CMOS) image sensors are a typical type of solid-state imaging sensor, widely used in digital cameras, mobile terminals, security monitoring terminals, and other devices. The basic working principle of a CMOS image sensor is as follows: when incident light shines on the pixel array of the image sensor, a photoelectric effect occurs, generating corresponding charges within the pixels. These charges are transferred through a readout circuit to an analog signal processing unit and a digital-to-analog converter, converting them into digital image signals for output. For a black-and-white digital image, the number corresponding to each pixel reflects the grayscale value of that pixel.

[0003] To acquire color digital images, color filter layers arranged in a specific pattern need to be placed on the pixel array of a CMOS image sensor to form a corresponding color pixel array. The Bayer array is a common method; see [link to relevant documentation]. Figure 1 The basic unit of the Bayer array is a 2×2 four-pixel array, with one four-pixel array containing one red (R) pixel, one blue (B) pixel, and two green (G) pixels. Similar color filter layers to the Bayer array include the RYYB array, whose basic unit includes one red pixel, one blue pixel, and two yellow (Y) pixels. In addition, there is the RGBW array, whose basic unit includes one red pixel, one blue pixel, one green pixel, and one white (W) pixel.

[0004] In a color pixel array, pixels used to detect the intensity of short-wavelength visible light (called short-wavelength light pixels, such as blue pixels) and pixels used to detect the intensity of mid-wavelength visible light (called mid-wavelength light pixels, such as green pixels) have some response to red light in the 650nm–700nm wavelength range, but this response is not desired and is therefore called a false response. The false response of short-wavelength and mid-wavelength light pixels to red light in the 650nm–700nm wavelength range is influenced by the intrinsic properties of the color filter layer material. This false response of short-wavelength and mid-wavelength light pixels to red light in the 650nm–700nm wavelength range will cause color distortion in the color image reproduced by the image sensor.

[0005] In view of this, it is necessary to provide an imaging device and apparatus that can reduce the false response of short-wavelength or mid-wavelength optical pixels to red light in the 650nm-700nm band, thereby improving the accuracy of color image imaging. Summary of the Invention

[0006] This application provides an image sensor and its manufacturing method, as well as an imaging device and terminal equipment using the image sensor. The image sensor and its manufacturing method, the imaging device and terminal equipment can solve the above-mentioned problems.

[0007] A first aspect of this application provides an image sensor, the image sensor including a pixel array having multiple basic units, each basic unit including a first pixel, a second pixel, and a third pixel; the pixel array includes, in the vertical direction, a color filter layer including a first filter sub-region, a second filter sub-region, and a third filter sub-region, the first filter sub-region corresponding to the first pixel, for transmitting light of a first wavelength band and filtering out light of other wavelength bands besides the first wavelength band, the second filter sub-region corresponding to the second pixel, for transmitting light of a second wavelength band and filtering out light of other wavelength bands besides the second wavelength band, and the third filter sub-region corresponding to the third pixel, for transmitting light of a third wavelength band. It filters out light of all wavelengths except the third wavelength band, wherein the wavelength of the first wavelength band is smaller than the wavelength of the second wavelength band, and the wavelength of the second wavelength band is smaller than the wavelength of the third wavelength band; a first substrate layer has a first groove extending towards the first substrate layer and corresponding to the first photofilter region and a second groove corresponding to the second photofilter region formed on the front side of the first substrate layer away from the color filter layer; a first photoelectric conversion region is formed between the first groove and the first photofilter region; a second photoelectric conversion region is formed between the second groove and the second photofilter region; and a third light filter region is formed between the region corresponding to the third photofilter region and the first substrate layer. The system includes an electro-conversion region, wherein the depth of the first groove is greater than the depth of the second groove; a dielectric layer, including a body and a first embedded portion and a second embedded portion connected to the body, wherein the body is disposed on the side of the first substrate layer away from the color filter layer, the first embedded portion is located in the first groove, and the second embedded portion is located in the second groove; a first floating diffusion region, a second floating diffusion region, and a third floating diffusion region, wherein the first floating diffusion region, the second floating diffusion region, and the third floating diffusion region are formed within the first substrate layer; and a first gate, a second gate, and a third gate, wherein the first gate, the second gate, and the third gate are disposed within the dielectric layer. The first gate is located between the first photoelectric conversion region and the first floating diffusion region, the second gate is located between the second photoelectric conversion region and the second floating diffusion region, and the third gate is located between the third photoelectric conversion region and the third floating diffusion region. The first gate is used to control the migration of charge in the first photoelectric conversion region to the first floating diffusion region, the second gate is used to control the migration of charge in the second photoelectric conversion region to the second floating diffusion region, and the third gate is used to control the migration of charge in the third photoelectric conversion region to the third floating diffusion region. The second substrate is disposed on one side of the dielectric layer.

[0008] The image sensor provided in this application embodiment, by setting a first groove and a second groove of reasonable depth in the regions of the first substrate layer corresponding to the first pixel and the second pixel respectively, reasonably sets the effective thickness of the regions of the first substrate layer corresponding to the first pixel and the second pixel. This ensures that the light of the target wavelength band of the first pixel and the second pixel has a high absorption ratio and photoelectric conversion efficiency within the effective thickness of the corresponding regions of the first substrate layer, and reduces the absorption ratio and photoelectric conversion efficiency of the light of the non-target wavelength band (red light of 650nm to 700nm) of the first pixel and the second pixel within the effective thickness of the corresponding regions of the first substrate layer. This reduces the interference of the non-target wavelength band light (red light of 650nm to 700nm) on the first pixel and the second pixel, thereby improving the accuracy of color image imaging of the image sensor.

[0009] According to the first aspect above, in an optional embodiment of this application, the light in the first band is short-wavelength visible light.

[0010] According to the first aspect above, in an optional embodiment of this application, the light in the second band is mid-band visible light.

[0011] According to the first aspect above, in one optional embodiment of this application, a corresponding pixel array, such as a Bayer array or an RYYB array, can be selected as needed.

[0012] According to the first aspect above, in an optional embodiment of this application, the first gate includes a first portion, a second portion and a third portion. The first portion is located outside the first groove. The upper end of the second portion is connected to one end of the first portion. The second portion is in contact with the inner wall of the first groove. The lower end of the second portion is connected to one end of the third portion. The third portion is located at the bottom of the first groove.

[0013] According to the first aspect above, in an optional embodiment of this application, the second gate includes a fourth part, a fifth part, and a sixth part. The fourth part is located outside the second groove. The upper end of the fifth part is connected to one end of the fourth part. The fifth part is in contact with the inner wall of the second groove. The lower end of the fifth part is connected to one end of the sixth part. The sixth part is located at the bottom of the second groove.

[0014] The image sensor provided in this application embodiment can improve the transmission efficiency of charge migration from the first photoelectric conversion region to the first floating diffusion region controlled by the first gate to the bottom of the first groove and the second groove, respectively, by extending the first gate and the second gate to the bottom of the first groove and the second groove, respectively. This can further improve the detection accuracy of the first pixel and the second pixel, and improve the accuracy of color image imaging of the image sensor.

[0015] According to the first aspect above, in an optional embodiment of this application, the image sensor is a back-illuminated image sensor or a stacked image sensor.

[0016] A second aspect of this application provides an imaging device, the imaging device including an image sensor, circuit board, cutoff filter, lens assembly and support body as described in any of the above claims;

[0017] The lens assembly is mounted above the cutoff filter via the bracket body for converging incident light; the cutoff filter is mounted above the image sensor via the bracket body for filtering the incident light converged by the lens assembly; the image sensor is mounted on the circuit board for receiving the light filtered by the cutoff filter and forming an image.

[0018] According to the second aspect above, in an optional embodiment of this application, the cutoff filter is a 700nm cutoff filter, which is used to filter out light with a wavelength of 700nm or higher.

[0019] The image sensor in the imaging device reduces the influence of red light in the 650nm-700nm wavelength band on the first and second pixels by reasonably setting the distance between the photoelectric conversion area of ​​different pixels and the color filter layer, and by setting the first groove and the second groove below the first photoelectric conversion area and the second photoelectric conversion area respectively. At the same time, a 700nm infrared cutoff filter is set above the image sensor to filter out light with wavelengths above 700nm, avoiding excessive light intake to the third pixel and overexposure of the red pixel, thereby improving the accuracy of color image imaging by the image sensor.

[0020] A third aspect of this application provides a terminal device, which includes the image sensor or imaging device described in any of the above claims.

[0021] A fourth aspect of this application provides a method for fabricating an image sensor, wherein the image sensor is any one of the image sensors described above. The method for fabricating the image sensor includes: forming a first groove corresponding to a first pixel and a second groove corresponding to a second pixel extending into the first substrate layer on the front side of a first substrate layer, wherein the depth of the first groove is greater than the depth of the second groove; forming a first gate corresponding to the first pixel, a second gate corresponding to the second pixel, and a third gate corresponding to a third pixel on the front side of the first substrate layer; and implanting ions into the first substrate layer on both sides of the first gate to form a first photoelectric conversion region and a first floating diffusion region. In the first substrate layer, ions are implanted on both sides of the second gate to form a second photoelectric conversion region and a second floating diffusion region. Ions are implanted on both sides of the third gate to form a third photoelectric conversion region and a third floating diffusion region. The first photoelectric conversion region corresponds to the first groove, and the second photoelectric conversion region corresponds to the second groove. A dielectric material is deposited to cover the front surface of the first substrate layer to form a first sublayer of the dielectric layer, and the surface of the first sublayer is ground flat. A metal interconnect layer is formed. The second substrate layer is bonded to the metal interconnect layer, and the back side of the first substrate layer is thinned. An anti-reflection layer, a color filter layer, and a microlens are formed on the back side of the first substrate layer 130.

[0022] According to the fourth aspect above, in an optional embodiment of this application, forming a first gate corresponding to a first pixel, a second gate corresponding to a second pixel, and a third gate corresponding to a third pixel on the front side of the first substrate layer includes:

[0023] The first gate includes a first part, a second part, and a third part. The first part is located outside the first groove. The upper end of the second part is connected to one end of the first part and is in contact with the inner wall of the first groove. The lower end of the second part is connected to one end of the third part. The third part is located at the bottom of the first groove. The second gate includes a fourth part, a fifth part, and a sixth part. The fourth part is located outside the second groove. The upper end of the fifth part is connected to one end of the fourth part and is in contact with the inner wall of the second groove. The lower end of the fifth part is connected to one end of the sixth part. The sixth part is located at the bottom of the second groove.

[0024] The fabrication method provided in this application provides a first groove and a second groove of reasonable depth in the regions of the first substrate layer corresponding to the first pixel and the second pixel, respectively. This reasonably sets the effective thickness of the regions of the first substrate layer corresponding to the first pixel and the second pixel, thereby ensuring that the light of the target wavelength band of the first pixel and the second pixel has a high absorption ratio and photoelectric conversion efficiency within the effective thickness of the corresponding regions of the first substrate layer. It also reduces the absorption ratio and photoelectric conversion efficiency of non-target wavelength band light (red light of 650nm to 700nm) of the first pixel and the second pixel within the effective thickness of the corresponding regions of the first substrate layer, thereby reducing the interference of non-target wavelength band light (red light of 650nm to 700nm) on the first pixel and the second pixel, and thus improving the accuracy of color image imaging of the image sensor. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the RGGB array, the basic unit of a Bayer array;

[0026] Figure 2 yes Figure 1 The cross-sectional view of the RGGB array shown along the dashed line A-A';

[0027] Figure 3 This is a schematic diagram of the structure of a CMOS image sensor provided in an embodiment of this application;

[0028] Figure 4 These are curves showing the absorption depth of light of different wavelengths in single-crystal silicon material;

[0029] Figure 5 This is a schematic diagram of the structure of a CMOS image sensor provided in another embodiment of this application;

[0030] Figure 6 This is an imaging device provided in one embodiment of the present application;

[0031] Figures 7-13 This is a schematic diagram of the structure formed by each step of the fabrication method of a CMOS image sensor provided in an embodiment of this application;

[0032] Figure 14 This is a schematic diagram of a possible implementation of step two of the fabrication method of a CMOS image sensor provided in an embodiment of this application.

[0033] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] CMOS image sensors include pixel arrays with multiple basic units, each including a first pixel, a second pixel, and a third pixel. These basic units are the smallest units used for imaging. A common example of a pixel array is the Bayer array, where the basic unit is a 2x2 four-pixel array (RGGB). Figure 1 As shown, one RGGB array contains one red pixel, one blue pixel, and two green pixels. See also... Figure 2 , Figure 1 The cross-sectional view of the RGGB array along the dashed line A-A' shown is as follows: Figure 2 As shown, the pixel array of the CMOS image sensor includes a color filter layer 20, a first substrate layer 30, a dielectric layer 40, and a second substrate layer 50 in the vertical direction. Specifically, the CMOS image sensor 10 is a back-illuminated image sensor or a stacked image sensor.

[0036] The color filter layer 20 includes a first filter sub-region 21, a second filter sub-region 22, and a third filter sub-region 23. The first filter sub-region 21 corresponds to the first pixel 11 and is used to transmit light in the first wavelength band and filter out light in other wavelength bands. The second filter sub-region 22 corresponds to the second pixel 12 and is used to transmit light in the second wavelength band and filter out light in other wavelength bands. The third filter sub-region 23 corresponds to the third pixel 13 and is used to transmit light in the third wavelength band and filter out light in other wavelength bands. Specifically, the first pixel 11 is a blue pixel, and the corresponding first filter sub-region 21 is a blue filter sub-region used to transmit blue light; the second pixel 12 is a green pixel, and the corresponding second filter sub-region 22 is a green filter sub-region used to transmit green light; the third pixel 13 is a red pixel, and the corresponding third filter sub-region 23 is a red filter sub-region used to transmit red light.

[0037] The back surface of the first substrate layer 30 is the light-incident surface, and it is connected to the color filter layer 20. A first photoelectric conversion region 31, a second photoelectric conversion region 33, a third photoelectric conversion region 35, a first floating diffusion region 32, a second floating diffusion region 34, and a third floating diffusion region 36 are formed within the first substrate layer 30. Specifically, the first photoelectric conversion region 31 and the first floating diffusion region 32 correspond to the first filter region 21; the second photoelectric conversion region 33 and the second floating diffusion region 34 correspond to the second filter region 22; and the third photoelectric conversion region 35 and the third floating diffusion region 36 correspond to the third filter region 23. Specifically, the first substrate layer 30 can be a single-crystal silicon substrate with a first doping type, typically a silicon epitaxial layer. Through ion implantation, photoelectric conversion regions and floating diffusion regions can be formed in the regions of the first substrate layer 30 corresponding to different pixels. For example, when the first substrate layer 30 is P-type boron doped, different concentrations of N-type doping elements, such as phosphorus or arsenic, can be implanted into two sub-regions in the region corresponding to the first pixel 11 in the first substrate layer 30, respectively, to form the first photoelectric conversion region 31 and the first floating diffusion region 32; the second photoelectric conversion region 33, the second floating diffusion region 34, the third photoelectric conversion region 35 and the third floating diffusion region 36 can also be formed in the same way.

[0038] The CMOS image sensor 10 further includes a first gate 41, a second gate 42, and a third gate 43, which are disposed within the dielectric layer 40 and are connected to the first substrate layer 30. The first gate 41 is located between the first photoelectric conversion region 31 and the first floating diffusion region 32, and is used to control the charge migration in the first photoelectric conversion region 31 to the first floating diffusion region 32; the second gate 42 is located between the second photoelectric conversion region 33 and the second floating diffusion region 34, and is used to control the charge migration in the second photoelectric conversion region 33 to the second floating diffusion region 34; the third gate 43 is located between the third photoelectric conversion region 35 and the third floating diffusion region 36, and is used to control the charge migration in the third photoelectric conversion region 35 to the third floating diffusion region 36. Specifically, the materials of the first gate 41, the second gate 42, and the third gate 43 can be polysilicon. The structure in which the first gate 41, the second gate 42, and the third gate 43 are connected to the first substrate layer 30 can be fabricated through processes such as polysilicon layer deposition, polysilicon layer photolithography, and polysilicon layer etching.

[0039] The dielectric layer 40 includes a body 47 and a first recess 44, a second recess 45, and a third recess 46 disposed on the body 47. The body 47 is connected to the first substrate layer 30. The first gate 41 is located in the first recess 44, the second gate 42 is located in the second recess 45, and the third gate 43 is located in the third recess 46. Generally, the dielectric layer 40 includes a metal interconnect layer, which can form a functional circuit, such as applying control signals to the first gate 41, the second gate 42, and the third gate 43, and reading out the charge quantity of the first floating diffusion region 32, the second floating diffusion region 34, and the third floating diffusion region 36.

[0040] The second substrate layer 50 is disposed on one side of the dielectric layer 40. The second substrate layer 50 can serve as a support.

[0041] In a practical application scenario, incident light from the outside illuminates the pixel array of the CMOS image sensor 10. The first filter region 21 of the first pixel 11 transmits blue light and filters out light other than blue light; the second filter region 22 of the second pixel 12 transmits green light and filters out light other than green light; and the third filter region 23 of the third pixel 13 transmits red light and filters out light other than red light. The blue, green, and red light transmitted through the color filter layer 20 are absorbed and converted into corresponding charges after entering the first substrate layer 30. Specifically, the first charge located in the first photoelectric conversion region 31 migrates to the first floating diffusion region 32 under the control of the first gate 41; the second charge located in the second photoelectric conversion region 33 migrates to the second floating diffusion region 34 under the control of the second gate 42; and the third charge located in the third photoelectric conversion region 35 migrates to the third floating diffusion region 36 under the control of the third gate 43. (Readout circuit) Figure 2 (Not shown in the image) The charge quantities in the first floating diffusion region 32, the second floating diffusion region 34, and the third floating diffusion region 36 are read respectively, and the information is transmitted to the computing processing circuit ( Figure 2 (Not shown in the image), after processing by the computational processing circuit, digital signals corresponding to the first pixel 11, the second pixel 12, and the third pixel 13 can be obtained. The magnitude of the digital signal represents the intensity of the target wavelength light in the incident light from the outside world illuminating that pixel. Specifically, the magnitude of the digital signal corresponding to the red pixel represents the intensity of red light in the incident light from the outside world illuminating the red pixel, the magnitude of the digital signal corresponding to the green pixel represents the intensity of green light in the incident light from the outside world illuminating the green pixel, and the magnitude of the digital signal corresponding to the blue pixel represents the intensity of blue light in the incident light from the outside world illuminating the blue pixel. After obtaining the digital signal of each pixel, the CMOS image sensor also performs post-processing, such as de-mosaicing, white balance correction, and color space conversion, to finally obtain a color digital image.

[0042] Ideally, the magnitude of the digital signal corresponding to each pixel represents only the intensity of the target wavelength light in the incident light illuminating that pixel. In this case, the image sensor can reproduce color images well. However, short-wavelength pixels (such as blue pixels) and mid-wavelength pixels (such as green pixels) exhibit certain false responses to red light in the 650nm–700nm wavelength range. This is due to the intrinsic properties of the color filter layer material. These false responses reduce the accuracy of color image imaging by the CMOS image sensor.

[0043] Please refer to Figure 3 This application provides a CMOS image sensor that can improve the accuracy of color image imaging. The CMOS image sensor 20 includes a pixel array with multiple basic units, including a first pixel 111, a second pixel 112, and a third pixel 113. Specifically, in this embodiment, the pixel array is a Bayer array, the first pixel 111 is a blue pixel, the second pixel 112 is a green pixel, and the third pixel 113 is a red pixel. Light in the 650nm-700nm wavelength band is not the target wavelength for the first pixel 111 and the second pixel 112. The first pixel 111 and the second pixel 112 have a certain degree of false response to light in the 650nm-700nm wavelength band, which should be suppressed as much as possible. The third pixel 113 has an effective response to light in the 650nm-700nm wavelength band. The pixel array of the CMOS image sensor 20 includes a color filter layer 120, a first substrate layer 130, a dielectric layer 140, and a second substrate layer 150 in the vertical direction.

[0044] The color filter layer 120 includes a first filter sub-region 121, a second filter sub-region 122, and a third filter sub-region 123. The first filter sub-region 121 corresponds to a first pixel 111 and is used to transmit light of a first wavelength band and filter out light of other wavelength bands besides the first wavelength band; the second filter sub-region 122 corresponds to a second pixel 112 and is used to transmit light of a second wavelength band and filter out light of other wavelength bands besides the second wavelength band; the third filter sub-region 123 corresponds to a third pixel 113 and is used to transmit light of a third wavelength band and filter out light of other wavelength bands besides the third wavelength band. Among them, the wavelength of the first band is shorter than the wavelength of the second band, and the wavelength of the second band is shorter than the wavelength of the third band; specifically, the first filter sub-region 121 transmits blue light and filters out light of other bands except blue light, the second filter sub-region 122 transmits green light and filters out light of other bands except green light, and the third filter sub-region 123 transmits red light and filters out light of other bands except red light. Among them, red light has the longest wavelength, green light is the second longest, and blue light has the shortest wavelength.

[0045] The back side of the first substrate layer 130 is connected to the color filter layer 120. A first groove 137 extending towards the first substrate layer 130 and corresponding to the first filter region 121 and a second groove 138 corresponding to the second filter region 122 are formed on the front side of the first substrate layer 130. A first photoelectric conversion region 131 is formed between the first groove 137 and the first filter region 121. A second photoelectric conversion region 133 is formed between the second groove 138 and the second filter region 122. A third photoelectric conversion region 135 is formed in the region of the first substrate layer 130 corresponding to the third pixel 113. The depth of the first groove 137 is greater than the depth of the second groove 138.

[0046] The dielectric layer 140 includes a body 146 and a first embedding portion 144 and a second embedding portion 145 connected to the body 146. The first embedding portion 144 is located in the first groove 137, and the second embedding portion 145 is located in the second groove 138.

[0047] The CMOS image sensor also includes a first floating diffusion region 132, a second floating diffusion region 134 and a third floating diffusion region 136, which are formed within a first substrate layer 130.

[0048] The CMOS image sensor also includes a first gate 141, a second gate 142, and a third gate 143. All three gates are disposed within the dielectric layer 140 and are connected to the first substrate layer 130. The first gate 141 is horizontally located between the first photoelectric conversion region 131 and the first floating diffusion region 132, and is used to control the migration of charge from the first photoelectric conversion region 131 to the first floating diffusion region 132. The second gate 142 is horizontally located between the second photoelectric conversion region 133 and the second floating diffusion region 134, and is used to control the migration of charge from the second photoelectric conversion region 133 to the second floating diffusion region 134. The third gate 143 is horizontally located between the third photoelectric conversion region 135 and the third floating diffusion region 136, and is used to control the migration of charge from the third photoelectric conversion region 135 to the third floating diffusion region 136.

[0049] The second substrate layer 150 is bonded to the dielectric layer 140 and can serve as a support.

[0050] For example, the first substrate layer 130 is a single-crystal silicon substrate with a first doping type, typically a silicon epitaxial layer, specifically a p-type boron-doped silicon substrate. A first groove 137 is formed on the front side of the first substrate layer 130 in the region corresponding to the first pixel 111, and a second groove 138 is formed on the front side of the first substrate layer 130 in the region corresponding to the second pixel 112. By injecting different concentrations of N-type doping elements into the two sub-regions of the region corresponding to the first pixel 111 of the first substrate layer 130, an N-type first photoelectric conversion region 131 and an N-type first floating diffusion region 132 are formed. By injecting different concentrations of N-type doping elements into the two sub-regions of the region corresponding to the second pixel 112 of the first substrate layer 130, an N-type second photoelectric conversion region 133 and an N-type first floating diffusion region 134 are formed. By injecting different concentrations of N-type doping elements into the two sub-regions of the region corresponding to the third pixel 113 of the first substrate layer 130, an N-type third photoelectric conversion region 135 and an N-type third floating diffusion region 136 are formed.

[0051] The first gate 141, the second gate 142, and the third gate 143 can be made of polysilicon. The structure in which the first gate 141, the second gate 142, and the third gate 143 are connected to the first substrate layer 130 can be fabricated through processes such as polysilicon layer deposition, polysilicon layer photolithography, and polysilicon layer etching.

[0052] The dielectric layer 140 can be made of silicon oxide, silicon nitride, silicon oxynitride, fluorosilicone glass, phosphosilicate glass, borosilicate glass, or combinations thereof. Chemical vapor deposition (CVD) is typically used to deposit the material. After deposition, the surface needs to be smoothed, usually using chemical mechanical polishing (CMP). The dielectric layer 140 also includes a metal interconnect layer, which specifically includes contact holes, metal layers, conductive vias, etc. This interconnect layer can apply control signals to the first gate 141, the second gate 142, and the third gate 143, and read out the charge quantity of the first floating diffusion region 132, the second floating diffusion region 134, and the third floating diffusion region 136.

[0053] The second substrate layer 150 is bonded to the dielectric layer 140, and the bonding process can be a bonding process; the second substrate layer 150 can be a bare silicon wafer or an image signal processing wafer (ISP wafer).

[0054] In a practical application scenario, incident light from the outside illuminates the CMOS image sensor 20. The first filter sub-region 121 corresponding to the first pixel 111 transmits light of the first wavelength band and filters out signals of other wavelength bands besides the first wavelength band. The second filter sub-region 122 corresponding to the second pixel 112 transmits light of the second wavelength band and filters out light of other wavelength bands besides the second wavelength band. The third filter sub-region 123 corresponding to the third pixel 113 transmits light of the third wavelength band and filters out light of other wavelength bands besides the third wavelength band. For example, the first filter sub-region 121 of the first pixel 111 transmits blue light and filters out light other than blue light, the second filter sub-region 122 of the second pixel 112 transmits green light and filters out light other than green light, and the third filter sub-region 123 of the third pixel 113 transmits red light and filters out light other than red light. When light of the first, second, and third wavelength bands enters the first substrate layer 130, it is absorbed and converted into corresponding charges. Specifically, the first charge located in the first photoelectric conversion region 131 migrates to the first floating diffusion region 132 under the control of the first gate 141; the second charge located in the second photoelectric conversion region 133 migrates to the second floating diffusion region 134 under the control of the second gate 142; and the third charge located in the third photoelectric conversion region 135 migrates to the third floating diffusion region 136 under the control of the third gate 143. (Reading circuit) Figure 3 (Not shown in the image) respectively reads the charge signals in the first floating diffusion region 132, the second floating diffusion region 134, and the third floating diffusion region 136, and transmits the information to the computing processing circuit ( Figure 3 (Not shown in the image), after processing by the computing circuit, digital signals of the first pixel 111, the second pixel 112, and the third pixel 113 can be obtained. Based on the digital signals, color image imaging can be performed.

[0055] In this embodiment, by reasonably setting grooves of different depths on the regions of the first substrate layer 130 corresponding to the first pixel 111 and the second pixel 112, the absorption and photoelectric conversion of light in the 650m-700nm wavelength band by the first pixel 111 and the second pixel 112 are reduced, thereby reducing the interference of light in the 650m-700nm wavelength band on the first pixel 111 and the second pixel 112 and improving the accuracy of color image imaging of the CMOS image sensor 20.

[0056] External incident light passes through the color filter layer 120 and enters the first substrate layer 130. As the depth of the first substrate layer 130 gradually increases, the absorption ratio of the incident light in the first substrate layer 130 gradually decreases; that is, the attenuation ratio of the incident light intensity decreases with increasing depth of the first substrate layer 130. The attenuation ratio of the incident light is greatest at the surface of the first substrate layer 130. When the attenuation ratio of the incident light in the first substrate layer 130 is 1 / e (approximately 37%), the depth of the incident light in the first substrate layer 130 at this point is called the absorption depth. Different wavelengths of light have different attenuation rates in the first substrate layer 130, therefore, different wavelengths of light have different absorption depths in the first substrate layer 130. Taking common single-crystal silicon as an example, the absorption depths of different wavelengths of light in single-crystal silicon are as follows: Figure 4 As shown.

[0057] For example, the thickness of the first substrate layer 130 is 5µm, and a first groove 137 with a depth of 4.2µm is provided on the area of ​​the first substrate layer 130 corresponding to the first pixel 111. The distance from the bottom of the first groove 137 to the back surface of the first substrate layer 130 is called the effective thickness of the area of ​​the first substrate layer 130 corresponding to the first pixel 111, and the effective thickness of the first pixel 111 is 0.8µm. Figure 4 It is known that the absorption depth of blue light (mainly wavelength 400nm-450nm) in single-crystal silicon is approximately 0.4µm-0.8µm. Therefore, the target wavelength blue light of the first pixel 111 has a high absorption ratio and photoelectric conversion efficiency in the region of the first substrate layer 130. Since the absorption depth of red light in the 650nm-700nm wavelength band is approximately 3.5µm-5µm, a large amount of red light in the 650nm-700nm wavelength band can be absorbed and photoelectric converted in the region of the first substrate layer with a depth of 0.8µm-5µm. However, since the effective thickness of the region of the first substrate layer 130 corresponding to the first pixel 111 is 0.8µm, the absorption ratio and photoelectric conversion efficiency of non-target wavelength light (red light in the 650nm-700nm wavelength band) of the first pixel 111 in the region of the first substrate layer 130 are relatively low. This reduces the impact of non-target wavelength light (red light in the 650nm-700nm wavelength band) on the first pixel 111, improving the detection accuracy of the first pixel 111.

[0058] Similarly, the thickness of the first substrate layer 130 is 5µm, and a second groove 138 with a depth of 3.3µm is provided on the area of ​​the first substrate layer 130 corresponding to the second pixel 112. The distance from the bottom of the second groove 138 to the back surface of the first substrate layer 130 is called the effective thickness of the area of ​​the first substrate layer 130 corresponding to the second pixel 112, and the effective thickness of the second pixel 112 is 1.7µm. Figure 4It is known that the absorption depth of green light (mainly wavelength 500nm-560nm) in single-crystal silicon is approximately 0.9um to 1.7um. Therefore, the target wavelength green light of the second pixel 112 has a high absorption ratio and photoelectric conversion efficiency in the region of the first substrate layer 130. However, since the absorption depth of red light in the 650nm-700nm wavelength band is approximately 3.5um to 5um, a large amount of red light in the 650nm-700nm wavelength band can be absorbed and photoelectric converted in the region of the first substrate layer with a depth of 1.7um to 5um. But because the effective thickness of the region of the first substrate layer 130 corresponding to the second pixel 112 is 1.7um, the absorption ratio and photoelectric conversion efficiency of the non-target wavelength light (red light in the 650nm-700nm wavelength band) of the second pixel 112 in the region of the first substrate layer 130 are relatively low. This reduces the impact of the non-target wavelength light (red light in the 650nm-700nm wavelength band) on the second pixel 112, improving the detection accuracy of the second pixel 112.

[0059] For the third pixel 113, the red light in the 650nm-700nm band is the target band light. Therefore, the area of ​​the first substrate layer 130 corresponding to the third pixel 113 does not need to be provided with a groove. The distance from the front side to the back side of the first substrate 130 is the effective thickness of the area of ​​the first substrate layer 130 corresponding to the third pixel 113.

[0060] Therefore, in this embodiment, by reasonably setting the effective thickness of the area of ​​the first substrate layer 130 corresponding to different pixels, the false response of the first pixel 111 and the second pixel 112 to red light in the non-target wavelength band of 650-700nm is reduced, thereby improving the accuracy of color image imaging of the CMOS image sensor 20.

[0061] Furthermore, when the basic unit of the pixel array of a CMOS image sensor includes pixels capable of simultaneously detecting long-wavelength and short-wavelength light, or pixels capable of simultaneously detecting long-wavelength and mid-wavelength light, the region of the first substrate corresponding to the pixels capable of simultaneously detecting long-wavelength and short-wavelength light or the pixels capable of simultaneously detecting long-wavelength and mid-wavelength light does not need to have a groove. For example, when the pixel array of the CMOS image sensor is an RYYB array, the basic unit of the RYYB array includes one red pixel, two yellow pixels, and one blue pixel. The yellow pixel can transmit both red and green light simultaneously. Red light is long-wavelength light, and the yellow pixel's response to red light is an effective response. Therefore, there is no need to set a groove in the region of the first substrate corresponding to the yellow pixel. Thus, the RYYB array only needs to have a groove of a reasonable depth in the first substrate corresponding to the blue pixel.

[0062] Another embodiment of this application provides a CMOS image sensor, such as... Figure 5As shown, in Figure 3 Based on the CMOS image sensor shown, the gate corresponding to the pixel with a groove on the front side of the first substrate extends along one side of the groove to the bottom of the groove, thereby improving the transfer efficiency of charge migration from the photoelectric conversion region corresponding to the pixel to the corresponding floating diffusion region, thereby improving the detection accuracy of the pixel and improving the color accuracy of the color image imaging of the CMOS image sensor.

[0063] like Figure 5 As shown, the CMOS image sensor 30 includes a pixel array with multiple basic units, including a first pixel 211, a second pixel 212, and a third pixel 213. Specifically, in this embodiment, the pixel array is a Bayer array, the first pixel 211 is a blue pixel, the second pixel 212 is a green pixel, and the third pixel 213 is a red pixel. The pixel array of the CMOS image sensor 30 includes a color filter layer 220, a first substrate layer 230, a dielectric layer 240, and a second substrate layer 250 in the vertical direction.

[0064] The color filter layer 220 includes a first filter sub-region 221, a second filter sub-region 222, and a third filter sub-region 223. The first filter sub-region 221 corresponds to a first pixel 211 and is used to transmit light in a first wavelength band and filter out light in other wavelength bands besides the first wavelength band. The second filter sub-region 222 corresponds to a second pixel 212 and is used to transmit light in a second wavelength band and filter out light in other wavelength bands besides the second wavelength band. The third filter sub-region 223 corresponds to a third pixel 213 and is used to transmit light in a third wavelength band and filter out light in other wavelength bands besides the third wavelength band. The wavelength of the first wavelength band is smaller than the wavelength of the second wavelength band, and the wavelength of the second wavelength band is smaller than the wavelength of the third wavelength band. Specifically, the first filter region 221 transmits blue light while filtering out light of other wavelengths besides blue light, the second filter region 222 transmits green light while filtering out light of other wavelengths besides green light, and the third filter region 223 transmits red light while filtering out light of other wavelengths besides red light. Among these three, red light has the longest wavelength, followed by green light, and blue light has the shortest wavelength.

[0065] The back side of the first substrate layer 230 is connected to the color filter layer 220. A first groove 237 extending towards the first substrate layer 230 and corresponding to the first filter region 221 and a second groove 238 corresponding to the second filter region 222 are formed on the front side of the first substrate layer 230. A first photoelectric conversion region 231 is formed between the first groove 237 and the first filter region 221. A second photoelectric conversion region 233 is formed between the second groove 238 and the second filter region 222. A third photoelectric conversion region 235 is formed in the region of the first substrate layer 230 corresponding to the third pixel 213. The depth of the first groove 237 is greater than the depth of the second groove 238.

[0066] The dielectric layer 240 includes a body 246 and a first embedding portion 244 and a second embedding portion 245 connected to the body 246. The first embedding portion 244 is located in a first groove 237 and the second embedding portion 245 is located in a second groove 238.

[0067] The CMOS image sensor 30 also includes a first floating diffusion region 232, a second floating diffusion region 234 and a third floating diffusion region 236, which are formed within the first substrate layer 230.

[0068] The CMOS image sensor 30 further includes a first gate 241, a second gate 242, and a third gate 243. The first gate 241 includes a first portion, a second portion, and a third portion. The first portion is located on the front side of the first substrate layer 240 and is attached to the front side of the first substrate layer 240. One side of the second portion is connected to the first portion and is attached to the sidewall of the first groove 237. The third portion is connected to the other side of the second portion and is attached to the bottom of the first groove 237. The first portion, the second portion, and the third portion are a single unit. The first gate 241 is located horizontally between the first photoelectric conversion region 231 and the first floating diffusion region 232, and is used to control the migration of charge generated in the first photoelectric conversion region 231 to the first floating diffusion region 232. Similarly, the second gate 242 includes a fourth portion, a fifth portion, and a sixth portion. The fourth part is located on the front side of the first substrate 240 and is attached to the front side of the first substrate 240. One side of the fifth part is connected to the fourth part and is attached to the sidewall of the second groove 238. The sixth part is connected to the other side of the fifth part and is attached to the bottom of the second groove 238. The fourth part, the fifth part and the sixth part are a whole. The second gate 242 is located in the horizontal direction between the second photoelectric conversion region 233 and the second floating diffusion region 234, and is used to control the migration of charge generated in the second photoelectric conversion region 233 to the second floating diffusion region 234. The third gate 243 is attached to the front side of the first substrate 240 and is located in the horizontal direction between the third photoelectric conversion region 235 and the third floating diffusion region 235, and is used to control the migration of charge generated in the third photoelectric conversion region 235 to the third floating diffusion region 236.

[0069] The second substrate layer 250 is bonded to one side of the dielectric layer 240.

[0070] For example, the first substrate layer 230 is a single-crystal silicon substrate with a first doping type, typically a silicon epitaxial layer, specifically a p-type boron-doped silicon substrate. A first groove 237 is formed on the front side of the first substrate layer 230 in the region corresponding to the first pixel 211, and a second groove 238 is formed on the front side of the first substrate layer 230 in the region corresponding to the second pixel 212. By injecting different concentrations of N-type doping elements into the two sub-regions of the region corresponding to the first pixel 211 of the first substrate layer 230, an N-type first photoelectric conversion region 231 and an N-type first floating diffusion region 232 are formed. By injecting different concentrations of N-type doping elements into the two sub-regions of the region corresponding to the second pixel 212 of the first substrate layer 230, an N-type second photoelectric conversion region 233 and an N-type first floating diffusion region 234 are formed. By injecting different concentrations of N-type doping elements into the two sub-regions of the region corresponding to the third pixel 213 of the first substrate layer 230, an N-type third photoelectric conversion region 235 and an N-type third floating diffusion region 236 are formed.

[0071] The first gate 241, the second gate 242, and the third gate 243 can be made of polysilicon. The structure in which the first gate 241, the second gate 242, and the third gate 243 are in contact with the front side of the first substrate layer 230 can be fabricated through processes such as polysilicon layer deposition, polysilicon layer photolithography, and polysilicon layer etching.

[0072] The dielectric layer 240 can be made of silicon oxide, silicon nitride, silicon oxynitride, fluorosilicone glass, phosphosilicate glass, borosilicate glass, or combinations thereof. Chemical vapor deposition is typically used to deposit the material, and the surface needs to be smoothed after deposition, usually using chemical mechanical polishing. The dielectric layer 240 also includes a metal interconnect layer, which specifically includes contact holes, metal layers, conductive vias, etc. This interconnect layer can apply control signals to the first gate 241, the second gate 242, and the third gate 243, and read out the charge quantity of the first floating diffusion region 232, the second floating diffusion region 234, and the third floating diffusion region 236.

[0073] The second substrate layer 250 is bonded to the dielectric layer 240, and the bonding process can be a bonding process; the second substrate layer 250 can be a bare silicon wafer or an image signal processing wafer (ISP wafer).

[0074] In a practical application scenario, incident light from the outside illuminates the CMOS image sensor 30. The first filter sub-region 221 corresponding to the first pixel 211 transmits light of the first wavelength band and filters out signals of other wavelength bands besides the first wavelength band. The second filter sub-region 222 corresponding to the second pixel 212 transmits light of the second wavelength band and filters out signals of other wavelength bands besides the second wavelength band. The first filter sub-region 223 corresponding to the third pixel 213 transmits light of the third wavelength band and filters out signals of other wavelength bands besides the third wavelength band. For example, the first filter sub-region 221 of the first pixel 211 transmits blue light and filters out light other than blue light, the second filter sub-region 222 of the second pixel 212 transmits green light and filters out light other than green light, and the third filter sub-region 223 of the third pixel 213 transmits red light and filters out light other than red light. Light of the first, second, and third wavelengths is absorbed and converted into first, second, and third charges, respectively, after entering the first substrate layer 230. Specifically, the first charge located in the first photoelectric conversion region 231 migrates to the first floating diffusion region 232 under the control of the first gate 241; the second charge located in the second photoelectric conversion region 233 migrates to the second floating diffusion region 234 under the control of the second gate 242; and the third charge located in the third photoelectric conversion region 235 migrates to the third floating diffusion region 236 under the control of the third gate 243. The reading circuit reads the charge signals from the first, second, and third floating diffusion regions 232, 234, and 236, respectively, and transmits the information to the computing processing circuit. After processing by the computing processing circuit, digital signals for the first pixel 211, second pixel 212, and third pixel 213 are obtained. Based on these digital signals, color image imaging can be performed.

[0075] In this embodiment, the CMOS image sensor 30 sets a first groove 237 and a second groove 238 of reasonable depth in the regions of the first substrate layer 230 corresponding to the first pixel 211 and the second pixel 212, respectively. This reasonably sets the effective thickness of the regions of the first substrate layer 230 corresponding to the first pixel 211 and the second pixel 212, thereby ensuring that the light of the target wavelength band of the first pixel 211 and the second pixel 212 has a high absorption ratio and photoelectric conversion efficiency within the effective thickness of the corresponding regions of the first substrate layer 230. It also reduces the absorption ratio and photoelectric conversion efficiency of the non-target wavelength band light (650nm~700nm red light) of the first pixel 211 and the second pixel 212 within the effective thickness of the corresponding regions of the first substrate layer 230, thereby reducing the interference of the non-target wavelength band light (650nm~700nm red light) on the first pixel 211 and the second pixel 212, and thus improving the accuracy of color image imaging of the CMOS image sensor 30.

[0076] In addition, in this embodiment, one side of the first gate 241 extends along the sidewall of the first groove 237 to the bottom of the first groove 237, thereby reducing the distance between the first gate 241 and the first photoelectric conversion region 221, which improves the transmission efficiency of charge migration from the first photoelectric conversion region 221 to the first floating diffusion region 222, and thus improves the detection accuracy of the first pixel 211. Similarly, one side of the second gate 242 extends along the sidewall of the second groove 238 to the bottom of the second groove 238, thereby reducing the distance between the second gate 242 and the second photoelectric conversion region 223, which improves the transmission efficiency of charge migration from the second photoelectric conversion region 223 to the second floating diffusion region 224, and thus improves the detection accuracy of the second pixel 212.

[0077] Furthermore, extending one side of the first gate 241 and the second gate 242 to the bottom of the first groove 237 and the bottom of the second groove 238 respectively makes it easier to realize the structure in the process that one side of the first photoelectric conversion region 221 is aligned with the side of the first gate 241 extending to the first groove 237. Similarly, it is also easier to realize the structure that one side of the second photoelectric conversion region 223 is aligned with the side of the second gate 242 extending to the second groove 238.

[0078] This application provides an imaging device, such as... Figure 6 As shown. The imaging device 40 includes an image sensor 304, a circuit board 300, a cutoff filter 301, a lens assembly 302, and a support 303. The image sensor 304 is a CMOS image sensor as described in any of the embodiments of this application. The image sensor 304 is disposed on the circuit board 300. The cutoff filter 301 and the lens assembly 302 are placed above the CMOS image sensor 304 via the support 303, with the lens assembly 302 located above the cutoff filter 301. For example, the lens assembly 302 includes a convex lens and / or a concave lens, which can focus the incident light, converging the scene to the back focal plane of the lens assembly 302, i.e., the plane where the image sensor 304 is located. The cutoff filter 301 is used to filter the light beam after it has been focused by the lens assembly 302, and can be used to filter out invalid light information. The image sensor is used to receive the light filtered by the cutoff filter 301 and form an image. For example, the imaging device 40 can be a camera module of a camera.

[0079] In a preferred embodiment, the cutoff filter 301 can be an infrared cutoff filter. Specifically, the infrared cutoff filter can be a 700nm cutoff filter, used to filter out light above 700nm.

[0080] Because the filters for short-wavelength and mid-wavelength optical pixels exhibit a certain degree of false response to light in the 650nm–700nm wavelength range, existing technologies typically employ a 650nm cutoff filter above the image sensor to eliminate this false response. This 650nm cutoff filter filters out light with wavelengths above 650nm while maintaining high transmittance for visible light below 650nm. While the 650nm cutoff filter can resolve the color distortion problem in color images caused by the false response of short-wavelength and mid-wavelength optical pixels to red light in the 650nm–700nm wavelength range, it also reduces the amount of light entering the red pixels, worsening imaging performance in low-light scenes. The image sensor of this application embodiment, by setting appropriately deep grooves in the first substrates of short-wavelength and mid-wavelength optical pixels, reduces the absorption ratio of the first substrates of the short-wavelength and mid-wavelength optical pixels for light in the 650nm-700nm band, while ensuring sufficient absorption and photoelectric conversion of light in the target band of the short-wavelength and mid-wavelength optical pixels. This reduces the false response of the short-wavelength and mid-wavelength optical pixels to light in the 650nm-700nm band caused by the intrinsic characteristics of the filter. Therefore, this application embodiment does not require setting a 650nm cutoff filter above the pixel array to reduce the false response of short-wavelength and mid-wavelength optical pixels to red light in the 650nm-700nm band. Since light with wavelengths above 700nm has limited effective information for red pixels, and light above 700nm can pass through the filter of red pixels, this would result in excessive light intake for red pixels, causing the photoelectric conversion area to reach saturation, which would reduce the accuracy of the CMOS image sensor in reproducing image colors. Therefore, a 700nm infrared cutoff filter is placed above the CMOS image sensor to filter out light with wavelengths above 700nm, preventing excessive light from entering the red pixels and causing overexposure of the red pixels, thereby improving the accuracy of the CMOS image sensor in reproducing image colors.

[0081] This application provides a terminal device, which includes the image sensor or imaging device described in the various embodiments of this application. For example, the terminal device may be a camera, camcorder, or surveillance camera.

[0082] This application provides a method for fabricating a CMOS image sensor, which can be used to fabricate such a sensor. Figure 4 The image sensor shown, specifically, please refer to Figures 7-13 The manufacturing method includes:

[0083] Step 1: Form a first groove corresponding to the first pixel and a second groove corresponding to the second pixel on the front side of the first substrate layer, extending towards the first substrate layer. The depth of the first groove is greater than the depth of the second groove.

[0084] Please see Figure 7 For example, the first substrate layer 230 can be a monocrystalline silicon substrate, and the thickness of the first substrate layer 230 can be 4 μm. The first pixel 211 can be a blue pixel for detecting blue light. The second pixel 212 can be a green pixel for detecting green light. Since the absorption depth of blue light in the monocrystalline silicon substrate is 0.4 μm to 0.8 μm, and the absorption depth of green light in the monocrystalline silicon substrate is 0.9 μm to 1.7 μm, the depth of the first groove 237 can be set to 3.2 μm, and the depth of the second groove 238 can be set to 2.3 μm. The first groove 237 and the second groove 238 can be formed on the first substrate layer 230 by dry etching or wet etching processes, and the depth of the first groove 237 is greater than the depth of the second groove 238.

[0085] Step 2: Form a first gate corresponding to the first pixel, a second gate corresponding to the second pixel, and a third gate corresponding to the third pixel on the front side of the first substrate layer;

[0086] Please see Figure 8 Please see Figure 8 The first gate 241 includes a first portion, a second portion, and a third portion. The first portion of the first gate 241 is located outside the first groove 237. The upper end of the second portion of the first gate 241 is connected to one end of the first portion of the first gate 241, the second portion of the first gate 241 is in contact with the inner wall of the first groove 237, the lower end of the second portion of the first gate 241 is connected to one end of the third portion of the first gate 241, and the third portion of the first gate 241 is located at the bottom of the first groove 237. The second gate 241 includes a first portion, a second portion, and a third portion. The second gate 241 has four, five, and six parts. The fourth part of the second gate 241 is located outside the second groove 238. The upper end of the fifth part of the second gate 241 is connected to one end of the fourth part of the second gate 241. The fifth part of the second gate 241 is attached to the inner wall of the second groove 238. The lower end of the fifth part of the second gate 241 is connected to one end of the sixth part of the second gate 241. The sixth part of the second gate 241 is located at the bottom of the second groove 238. The third gate 243 is located on the front side of the first substrate layer 230.

[0087] Step 3: Ions are implanted into the first substrate layer on both sides of the first gate to form a first photoelectric conversion region and a first floating diffusion region. Ions are implanted into the first substrate layer on both sides of the second gate to form a second photoelectric conversion region and a second floating diffusion region. Ions are implanted into the first substrate layer on both sides of the third gate to form a third photoelectric conversion region and a third floating diffusion region. The first photoelectric conversion region corresponds to the first groove, and the second photoelectric conversion region corresponds to the second groove.

[0088] Please see Figure 9 For example, when the first substrate layer 230 is a p-type boron-doped silicon substrate, the implanted ions can be n-type doped elements such as phosphorus or arsenic. Specifically, the first photoelectric conversion region 231 is disposed between the first groove 237 and the back surface of the first substrate layer 230; the second photoelectric conversion region 233 is disposed between the second groove 238 and the back surface of the first substrate layer 230; and the third photoelectric conversion region 235 is disposed in the region of the first substrate layer 230 corresponding to the third pixel 213.

[0089] Step 4: Deposit dielectric material onto the front side of the first substrate to form the first sublayer of the dielectric layer, and grind the surface of the first sublayer smooth;

[0090] Please see Figure 10 For example, the formation of the first sublayer 2401 of the dielectric layer is usually carried out by chemical vapor deposition and requires multiple depositions. For example, silicon oxide with a thickness of about 20 to 40 nanometers is deposited first, followed by silicon nitride with a thickness of about 30 to 50 nanometers, and finally silicon oxide with a thickness of about 5 to 6 micrometers to fill all the depressions, including the first groove 237 and the second groove 238. Then the surface of the first sublayer 2401 is polished, usually by chemical mechanical polishing.

[0091] Step 5: Form a metal interconnect layer;

[0092] Please see Figure 11 For example, the dielectric layer 240 includes a metal interconnect layer 2402, which includes contact holes, a metal layer, and conductive vias. The metal interconnect layer 2402 may include multiple sub-layers, and each sub-layer is isolated from the others by an insulating dielectric material. The metal interconnect layer 2402 can apply control signals to the first gate 241, the second gate 242, and the third gate 243, and read out the charge quantity of the first floating diffusion region 232, the second floating diffusion region 234, and the third floating diffusion region 236.

[0093] Step 6: Bond the second substrate layer to the metal interconnect layer and thin the back side of the first substrate layer;

[0094] Please see Figure 12 For example, the front side of the second substrate layer 250 is planarized and then bonded to the metal interconnect layer 2402, and the back side of the first substrate layer 230 is thinned.

[0095] Step 7: Form an anti-reflection layer, a color filter layer, and a microlens on the back side of the first substrate.

[0096] Please see Figure 13For example, the anti-reflective layer 2301 and the microlens 2303 can be used to increase the amount of incident light, and the pattern of the color filter layer 2302 can be set as needed, for example, a Bayer array can be used.

[0097] The manufacturing method provided in this application embodiment, by setting a first groove 237 and a second groove 238 of reasonable depth in the regions of the first substrate layer 230 corresponding to the first pixel 211 and the second pixel 212, reasonably sets the effective thickness of the regions of the first substrate layer 230 corresponding to the first pixel 211 and the second pixel 212. This ensures that the light of the target wavelength band of the first pixel 211 and the second pixel 212 has a high absorption ratio and photoelectric conversion efficiency within the effective thickness of the corresponding regions of the first substrate layer 230, and reduces the absorption ratio and photoelectric conversion efficiency of the non-target wavelength band light (650nm~700nm red light) of the first pixel 211 and the second pixel 212 within the effective thickness of the corresponding regions of the first substrate layer 230. This reduces the interference of the non-target wavelength band light (650nm~700nm red light) on the first pixel 211 and the second pixel 212, thereby improving the accuracy of color image imaging of the CMOS image sensor 30.

[0098] Furthermore, by extending the first gate 241 and the second gate 242 to the bottom of the first groove 237 and the second groove 238 respectively, the transmission efficiency of the charge migration from the first photoelectric conversion region 231 to the first floating diffusion region 232 controlled by the first gate 141 can be improved, as can the transmission efficiency of the charge migration from the second photoelectric conversion region 233 to the second floating diffusion region 234 controlled by the second gate 242. This further improves the detection accuracy of the first pixel 211 and the second pixel 212, and enhances the accuracy of the CMOS image sensor in color image reproduction.

[0099] As one possible embodiment, this application provides another possible implementation of step two. Please refer to... Figure 14 For example, a first gate 141 is disposed outside the first recess 237, and one side of the first gate 141 is aligned with one side of the inner wall of the first recess 237; a second gate 142 is disposed outside the second recess 238, and one side of the second gate 142 is aligned with one side of the inner wall of the second recess 238; a third gate 143 is disposed on the front side of the first substrate layer 230. The materials of the first gate 141, the second gate 142, and the third gate 143 can be polysilicon, and the first gate 141, the second gate 142, and the third gate 143 can be formed by deposition of a polysilicon layer, photolithography of a polysilicon layer, and etching of a polysilicon layer.

[0100] It should be noted that, without conflict, the various embodiments and / or technical features described in this application can be arbitrarily combined with each other, and the resulting technical solutions should also fall within the protection scope of this application.

[0101] It should be understood that the specific examples in the embodiments of this application are only for the purpose of helping those skilled in the art to better understand the embodiments of this application, and are not intended to limit the scope of the embodiments of this application. Those skilled in the art can make various improvements and modifications based on the above embodiments, and all such improvements or modifications fall within the protection scope of this application.

[0102] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An image sensor, characterized in that, The image sensor includes a pixel array having multiple basic units, each basic unit including a first pixel, a second pixel, and a third pixel; the pixel array includes, in the vertical direction: A color filter layer includes a first filter sub-region, a second filter sub-region, and a third filter sub-region. The first filter sub-region corresponds to the first pixel and is used to transmit light in a first wavelength band and filter out light in other wavelength bands besides the first wavelength band. The second filter sub-region corresponds to the second pixel and is used to transmit light in a second wavelength band and filter out light in other wavelength bands besides the second wavelength band. The third filter sub-region corresponds to the third pixel and is used to transmit light in a third wavelength band and filter out light in other wavelength bands besides the third wavelength band. The wavelength of the first wavelength band is smaller than the wavelength of the second wavelength band, and the wavelength of the second wavelength band is smaller than the wavelength of the third wavelength band. A first substrate layer has a first groove extending toward the first substrate layer and corresponding to the first photofilter region, and a second groove corresponding to the second photofilter region, formed on the front side of the first substrate layer away from the color filter layer. A first photoelectric conversion region is formed between the first groove and the first photofilter region, a second photoelectric conversion region is formed between the second groove and the second photofilter region, and a third photoelectric conversion region is formed between the first substrate layer and the region corresponding to the third photofilter region. The depth of the first groove is set such that the effective thickness of the first photoelectric conversion region corresponds to the absorption depth of the first wavelength band light, and the depth of the second groove is set such that the effective thickness of the second photoelectric conversion region corresponds to the absorption depth of the second wavelength band light. The depth of the first groove is greater than the depth of the second groove. The dielectric layer includes a body and a first embedding portion and a second embedding portion connected to the body. The body is disposed on the side of the first substrate layer away from the color filter layer. The first embedding portion is located in the first groove, and the second embedding portion is located in the second groove. A first floating diffusion region, a second floating diffusion region, and a third floating diffusion region are formed within the first substrate layer. A first gate, a second gate, and a third gate are disposed within the dielectric layer and are connected to the first substrate layer. The first gate is located between the first photoelectric conversion region and the first floating diffusion region, the second gate is located between the second photoelectric conversion region and the second floating diffusion region, and the third gate is located between the third photoelectric conversion region and the third floating diffusion region. The first gate is used to control the migration of charge in the first photoelectric conversion region to the first floating diffusion region, the second gate is used to control the migration of charge in the second photoelectric conversion region to the second floating diffusion region, and the third gate is used to control the migration of charge in the third photoelectric conversion region to the third floating diffusion region. A second substrate layer is disposed on one side of the dielectric layer.

2. The image sensor according to claim 1, characterized in that, The light in the first band is short-wavelength visible light.

3. The image sensor according to claim 2, characterized in that, The light in the second band is mid-band visible light.

4. The image sensor according to claim 3, characterized in that, The pixel array is a Bayer array.

5. The image sensor according to any one of claims 1-4, characterized in that, The first gate includes a first part, a second part, and a third part. The first part is located outside the first groove. The upper end of the second part is connected to one end of the first part. The second part is in contact with the inner wall of the first groove. The lower end of the second part is connected to one end of the third part. The third part is located at the bottom of the first groove.

6. The image sensor according to claim 5, characterized in that, The second gate includes a fourth part, a fifth part, and a sixth part. The fourth part is located outside the second groove. The upper end of the fifth part is connected to one end of the fourth part. The fifth part is in contact with the inner wall of the second groove. The lower end of the fifth part is connected to one end of the sixth part. The sixth part is located at the bottom of the second groove.

7. The image sensor according to any one of claims 1-4 or 6, characterized in that, The image sensor is a back-illuminated image sensor or a stacked image sensor.

8. An imaging device, characterized in that, The imaging device includes an image sensor, circuit board, cutoff filter, lens assembly, and support body as described in any one of claims 1-4 or 6; The lens assembly is mounted above the cutoff filter via the bracket body to converge incident light; The cutoff filter is mounted above the image sensor via the bracket and is used to filter the incident light after it has been converged by the lens assembly. The image sensor is mounted on the circuit board and is used to receive light filtered by the cutoff filter and to form an image.

9. The imaging apparatus according to claim 8, characterized in that, The cutoff filter is a 700nm cutoff filter, which is used to filter out light with a wavelength of 700nm or higher.

10. A terminal device, characterized in that, The terminal device includes an image sensor as described in any one of claims 1-4 or 6, or an imaging device as described in any one of claims 8-9.

11. A method for manufacturing an image sensor, characterized in that, The image sensor is the image sensor according to any one of claims 1-4 or 6, and the method for manufacturing the image sensor includes: A first groove corresponding to a first pixel and a second groove corresponding to a second pixel are formed on the front side of the first substrate layer, extending toward the first substrate layer, wherein the depth of the first groove is greater than the depth of the second groove. A first gate corresponding to the first pixel, a second gate corresponding to the second pixel, and a third gate corresponding to the third pixel are formed on the front side of the first substrate layer; Ions are implanted into the first substrate layer on both sides of the first gate to form a first photoelectric conversion region and a first floating diffusion region. Ions are implanted into the first substrate layer on both sides of the second gate to form a second photoelectric conversion region and a second floating diffusion region. Ions are implanted into the first substrate layer on both sides of the third gate to form a third photoelectric conversion region and a third floating diffusion region. The first photoelectric conversion region corresponds to the first groove, and the second photoelectric conversion region corresponds to the second groove. A first sublayer of the dielectric layer is formed by depositing a dielectric material onto the positive surface of the first substrate layer, and the surface of the first sublayer is ground smooth. Forming a metal interconnect layer; The second substrate layer is bonded to the metal interconnect layer, and the back side of the first substrate layer is thinned. An anti-reflection layer, a color filter layer, and a microlens are formed on the back side of the first substrate layer.

12. The method for manufacturing an image sensor according to claim 11, characterized in that, The step of forming a first gate corresponding to the first pixel, a second gate corresponding to the second pixel, and a third gate corresponding to the third pixel on the front side of the first substrate layer includes: The first gate includes a first part, a second part, and a third part. The first part is located outside the first groove. The upper end of the second part is connected to one end of the first part. The second part is in contact with the inner wall of the first groove. The lower end of the second part is connected to one end of the third part. The third part is located at the bottom of the first groove. The second gate includes a fourth part, a fifth part, and a sixth part. The fourth part is located outside the second groove. The upper end of the fifth part is connected to one end of the fourth part. The fifth part is in contact with the inner wall of the second groove. The lower end of the fifth part is connected to one end of the sixth part. The sixth part is located at the bottom of the second groove.

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