A method for manufacturing a light-shielding semiconductor device and a light-shielding semiconductor device

Abstract

This application discloses a method for fabricating a light-shielding semiconductor device and the light-shielding semiconductor device itself, belonging to the field of semiconductor technology. By setting a light-shielding film on the surface of the photosensitive area of ​​the pixel requiring light shielding, less light enters the photosensitive area, thereby indirectly reducing the photosensitivity of the photosensitive area and achieving a wide dynamic range effect. Simultaneously, by setting the light-shielding film on the top surface of the metal grid, it can, on the one hand, block the light path refracted by the lens structure and forming crosstalk from reaching adjacent pixel sensing areas, thus preventing the generation of crosstalk light; on the other hand, it optimizes the overall pixel structure, ensuring a flat overall pixel structure, making subsequent color filter processes easier and preventing color filter depressions or protrusions, thereby improving image quality.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a method for fabricating a light-shielding semiconductor device and the light-shielding semiconductor device. Background Technology

[0002] With the development of autonomous driving technology in recent years, the demand for LFM (LED Flicker Mitigation) functionality in vehicle cameras, particularly in traffic light scenarios, is becoming increasingly strong. Because traffic lights use pulsed flashing, if the exposure time of the vehicle camera is less than 10ms, it will fail to capture the correct signal. Therefore, LFM functionality is crucial in the field of vehicle cameras, especially in autonomous driving. Simultaneously, high dynamic range is also required in autonomous driving. Preventing overexposure of the camera sensor when transitioning from a dark environment inside a tunnel to a bright, exposed scene outside is also an important technical indicator.

[0003] A current mainstream technical solution involves covering the photosensitive area of ​​each pixel in a back-illuminated image sensor with a light-shielding film to reduce the pixel's sensitivity. Due to this reduced sensitivity, it requires a longer exposure time to reach saturation compared to a normal pixel. Cameras using this structure can prevent interference from flashing traffic lights when capturing images. Furthermore, when exposed to strong light, the reduced sensitivity allows for a longer exposure time to reach saturation, effectively widening the sensor's dynamic range.

[0004] Generally, the light-shielding film 3 is as follows Figure 1 After the metal grid 2 is formed as shown, it is then processed as follows: Figure 2 and Figure 3 The thin film shown is formed by photolithography and etching using photoresist 6. This process is integrated into a traditional back-illuminated process flow, and like traditional back-illuminated (BSI) processes, it also has the following characteristics: Figure 4 The image crosstalk problem mentioned above: the crosstalk light path formed by the refraction of the lens structure 5 in the middle (dashed line in the figure) is transmitted to the area corresponding to the red color film 41 on the left through the dielectric layer 7 on top of the metal grid 2. This image crosstalk problem will affect the image quality.

[0005] One improvement is to integrate the light-shielding film into the back-illuminated color filter (BCF) process. The standard BCF process is as follows: Figure 5As shown, when integrating the light-shielding film process into the BCF process, there is a problem of over-etching of the oxide film layer 22. Since the structure of the metal grid 2 is a metal film layer 21-oxide film layer 22 structure, and the light-shielding film 3 covers the oxide film layer 22, when the light-shielding film 3 is etched away, the oxide film layer 22 cannot be well protected, often resulting in over-etching of the oxide film layer 22. For example... Figure 6 As shown, after the oxide film layer 22 is over-etched, it will affect the subsequent color filter process, causing the color filter layer to form protrusions or depressions, ultimately affecting the sensor image performance. Summary of the Invention

[0006] The purpose of this application is to provide a method for fabricating a light-shielding semiconductor device and the light-shielding semiconductor device, which can solve the problem of over-etching of the oxide film layer while ensuring light-shielding performance, thereby ensuring the stability of subsequent color filter processes and that the sensor image performance is not affected.

[0007] To achieve the above objectives, this application provides a method for fabricating a light-shielding semiconductor device, comprising:

[0008] A metal grid process is performed on the surface of a wafer to form a metal grid; the metal grid includes a metal film layer and an oxide film layer arranged sequentially along the thickness direction; the area not covered by the metal grid is the pixel photosensitive area; the pixel photosensitive area includes at least a first pixel photosensitive area that needs to be shielded from light.

[0009] A light-shielding film is deposited on the surface of the wafer having the metal grid, and the light-shielding film is made higher than the metal grid;

[0010] A portion of the light-shielding film on the surface of the photosensitive area of ​​the first pixel is etched away, while the light-shielding film on the top surface of the metal grille is retained;

[0011] After etching is completed, a color filter process is performed to form a color filter on the surface of the photosensitive area of ​​the pixel, and a lens structure is formed on the surface of the color filter to obtain a light-shielding semiconductor device.

[0012] Optionally, after depositing a light-shielding film on the wafer surface having the metal grid, such that the light-shielding film is higher than the metal grid, the method further includes:

[0013] The surface of the light-shielding film is subjected to a chemical mechanical polishing process, and the polished light-shielding film is made to be higher than the metal grid.

[0014] Optionally, the thickness of the light-shielding film on the surface of the metal grid after grinding is greater than 5000 Å.

[0015] Optionally, the pixel photosensitive area may further include a second pixel photosensitive area that does not require light blocking;

[0016] Accordingly, after depositing a light-shielding film on the wafer surface having the metal grid, and making the light-shielding film higher than the metal grid, the method further includes:

[0017] The light-shielding film on the surface of the photosensitive area of ​​the second pixel is etched away;

[0018] Accordingly, forming a color film on the surface of the photosensitive area of ​​the pixel includes:

[0019] The color filter is formed on the surface of the second pixel photosensitive area and on the surface of the first pixel photosensitive area.

[0020] Optionally, the etching away of a portion of the light-shielding film from the surface of the first pixel's photosensitive area includes:

[0021] The light-shielding film in the middle area of ​​the surface of the first pixel photosensitive area is etched away to form an opening; the opening penetrates the light-shielding film along the thickness direction; the area of ​​the opening is smaller than the area of ​​the first pixel photosensitive area; the size of the opening corresponds one-to-one with the photosensitivity of the first pixel photosensitive area;

[0022] Accordingly, forming a color film on the surface of the photosensitive area of ​​the pixel includes:

[0023] The color filter is filled into the opening.

[0024] Optionally, the etching away of a portion of the light-shielding film from the surface of the first pixel's photosensitive area includes:

[0025] The light-shielding film in multiple areas on the surface of the first pixel photosensitive area is etched away to form multiple independent light-shielding film pillars; the density of the light-shielding film pillars corresponds one-to-one with the photosensitivity of the first pixel photosensitive area;

[0026] Accordingly, forming a color film on the surface of the photosensitive area of ​​the pixel includes:

[0027] The colored film is filled between adjacent light-shielding film columns.

[0028] To achieve the above objectives, this application also provides a light-shielding semiconductor device, comprising: a wafer, wherein a metal grid is disposed on the surface of the wafer; the metal grid includes a metal film layer and an oxide film layer disposed sequentially along the thickness direction; the area not covered by the metal grid is a pixel photosensitive area; the pixel photosensitive area includes at least a first pixel photosensitive area that needs to be light-shielded;

[0029] The top surface of the metal grille is provided with a light-shielding film; the surface of the photosensitive area of ​​the first pixel is provided with the light-shielding film and a color filter; the surface of the color filter is provided with a lens structure.

[0030] Optionally, the pixel photosensitive area further includes a second pixel photosensitive area that does not require light blocking; the color film is disposed on the surface of the second pixel photosensitive area.

[0031] Optionally, the light-shielding film on the surface of the first pixel photosensitive area has an opening; the opening extends through the light-shielding film along the thickness direction; the opening is located in the middle region of the surface of the first pixel photosensitive area; the area of ​​the opening is smaller than the area of ​​the first pixel photosensitive area; the size of the opening corresponds one-to-one with the photosensitivity of the pixel photosensitive area.

[0032] The opening is filled with the color filter.

[0033] Optionally, multiple areas on the surface of the first pixel photosensitive area are each provided with an independent light-shielding film pillar; the density of the light-shielding film pillars corresponds one-to-one with the photosensitivity of the pixel photosensitive area;

[0034] The colored film is filled between adjacent light-shielding film columns.

[0035] This application provides a method for fabricating a light-shielding semiconductor device, comprising: performing a metal grid process on a wafer surface to form a metal grid; the metal grid includes a metal film layer and an oxide film layer sequentially disposed along the thickness direction; the area not covered by the metal grid is a pixel photosensitive area; the pixel photosensitive area includes at least a first pixel photosensitive area that needs to be light-shielded; depositing a light-shielding film on the wafer surface having the metal grid, such that the light-shielding film is higher than the metal grid; etching away a portion of the light-shielding film on the surface of the first pixel photosensitive area, while retaining the light-shielding film on the top surface of the metal grid; after etching, performing a color filter process to form a color filter on the surface of the pixel photosensitive area, and forming a lens structure on the surface of the color filter to obtain a light-shielding semiconductor device.

[0036] Obviously, by setting a light-shielding film on the surface of the photosensitive area of ​​the pixel that needs to be shielded, less light enters the photosensitive area of ​​the pixel, thereby indirectly reducing the photosensitivity of the photosensitive area of ​​the pixel and achieving a wide dynamic range effect. Simultaneously, by setting the light-shielding film on the top surface of the metal grid, it can, on the one hand, block the light path refracted by the lens structure and causing crosstalk from reaching the adjacent pixel sensing area, thus blocking the generation of crosstalk light; on the other hand, it optimizes the overall pixel structure, ensuring a flat overall pixel structure, making subsequent color filter processing easier and preventing color filter depressions or protrusions, thereby improving image quality. This application also provides a light-shielding semiconductor device with the above-mentioned beneficial effects. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figures 1 to 3 This is a schematic diagram of the traditional light-shielding film formation process;

[0039] Figure 4 This is a schematic diagram of the traditional BSI process.

[0040] Figure 5 This is a schematic diagram of the traditional BCF process;

[0041] Figure 6 A schematic diagram of the structure of a light-shielding film integrated using the traditional BCF process;

[0042] Figure 7 A flowchart illustrating a method for fabricating a light-shielding semiconductor device provided in this application embodiment;

[0043] Figures 8 to 15 This is a schematic flowchart illustrating a method for fabricating a light-shielding semiconductor device according to an embodiment of this application.

[0044] Figure 16 An optical path diagram of a light-shielding semiconductor device provided in an embodiment of this application.

[0045] The annotations in the attached figures are explained as follows:

[0046] 1-Wafer; 2-Metal grid; 21-Metal film layer; 22-Oxide film layer; 3-Light shielding film; 31-Opening; 32-Light shielding film pillar; 41-Red color film; 42-Blue color film; 43-Green color film; 5-Lens structure; 6-Photoresist; 7-Dielectric layer. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Please refer to Figure 7 , Figure 7 A flowchart illustrating a method for fabricating a light-shielding semiconductor device provided in this application embodiment, the method may include:

[0049] S101: A metal grid process is performed on the wafer surface to form a metal grid; the metal grid includes a metal film layer and an oxide film layer arranged sequentially along the thickness direction; the area not covered by the metal grid is the pixel photosensitive area; the pixel photosensitive area includes at least the first pixel photosensitive area that needs to be shielded from light.

[0050] Furthermore, in this embodiment, the photosensitive area of ​​a pixel may also include a second photosensitive area of ​​a pixel that does not require light blocking;

[0051] Accordingly, after step S102, the following may also be included:

[0052] The light-shielding film 3 on the surface of the photosensitive area of ​​the second pixel is etched away;

[0053] Accordingly, forming a color film on the surface of the pixel photosensitive area in step S104 may include:

[0054] A color film is formed on the surface of the second pixel photosensitive area, and a color film is also formed on the surface of the first pixel photosensitive area.

[0055] It should be noted that wafer 1 in this embodiment is wafer 1 prepared by back-illuminated process, which has already formed a photodiode structure in the front-end process and has completed the bonding, thinning and other processes in the back-illuminated process.

[0056] This embodiment does not limit the specific method of forming the metal grid 2, as long as it ensures that the metal grid 2 can be formed. For example, the following methods can be used:

[0057] A metal film layer 21 and an oxide film layer 22 are sequentially deposited along the thickness direction on the surface of wafer 1;

[0058] The metal film layer 21 and the oxide film layer 22 are subjected to photolithography, etching and cleaning processes to form a metal grid 2.

[0059] This embodiment does not limit the specific material of the metal film layer 21. For example, the material of the metal film layer 21 can be aluminum, tungsten or other metal media.

[0060] This embodiment does not limit the specific number of metal grids 2, which can be determined according to the actual situation. For example, four metal grids 2 can be formed. The area between adjacent metal grids 2 is not covered by the metal grids 2. This area is a pixel photosensitive area. This structure includes three pixel photosensitive areas.

[0061] S102: Deposit a light-shielding film on the surface of a wafer with a metal grid, and make the light-shielding film higher than the metal grid.

[0062] This embodiment does not limit the specific type of light-shielding film 3. The light-shielding film 3 can be, but is not limited to, a metal film, and the material of the metal film can be, but is not limited to, titanium oxide.

[0063] Furthermore, after step S102, this embodiment may further include: performing a chemical mechanical polishing process on the surface of the light-shielding film 3, so that the polished light-shielding film 3 is higher than the metal grid 2. It should be noted that, in this embodiment, performing a chemical mechanical polishing process on the light-shielding film 3 after deposition can ensure that the surface of the light-shielding film 3 is flat and free of protrusions and depressions.

[0064] This embodiment does not limit the specific thickness of the light-shielding film 3 after grinding, as long as the thickness of the light-shielding film 3 can achieve the purpose of light shielding. For example, the thickness of the light-shielding film 3 on the surface of the metal grid 2 after grinding can be greater than 5000 Å.

[0065] S103: Etch away part of the light-shielding film 3 on the surface of the first pixel photosensitive area, while retaining the light-shielding film 3 on the top surface of the metal grid 2.

[0066] This embodiment does not limit the specific etching method, as long as it ensures that only a portion of the light-shielding film 3 on the surface of the first pixel photosensitive area is etched away. For example, photolithography and etching processes can be used to etch away a portion of the light-shielding film 3 on the surface of the first pixel photosensitive area. Similarly, photolithography and etching processes can be used to etch away the light-shielding film 3 on the surface of the second pixel photosensitive area.

[0067] This embodiment does not limit the specific method of etching away the light-shielding film 3 on the surface of the first pixel photosensitive area; for example, the following two methods can be used:

[0068] (1) Please refer to Figure 14 The light-shielding film 3 in the middle area of ​​the first pixel photosensitive area is etched away to form an opening 31; the opening 31 penetrates the light-shielding film 3 along the thickness direction; the area of ​​the opening 31 is smaller than the area of ​​the first pixel photosensitive area; the size of the opening 31 corresponds one-to-one with the photosensitivity of the first pixel photosensitive area.

[0069] Accordingly, forming a color film on the surface of the pixel photosensitive area in step S104 may include:

[0070] Fill the opening 31 with a colored film.

[0071] It should be noted that in this embodiment, the photosensitivity of the first pixel photosensitive area can be controlled by controlling the size of the opening 31 (i.e., controlling the pixel photosensitivity ratio), thereby achieving the high dynamic range performance requirements of the image sensor. Furthermore, it should be noted that since the remaining light-shielding film 3 on the surface of the first pixel photosensitive area can simultaneously cover the sides of the metal grid 2 and the sides of the top surface of the metal grid 2, it can also block the crosstalk light path refracted by the lens structure 5 from reaching adjacent pixel sensing areas, thus preventing the generation of crosstalk light.

[0072] (2) Please refer to Figure 15The light-shielding film 3 of multiple areas on the surface of the first pixel photosensitive area is etched away to form multiple independent light-shielding film pillars 32; the density of the light-shielding film pillars 32 corresponds one-to-one with the photosensitivity of the first pixel photosensitive area.

[0073] Accordingly, forming a color film on the surface of the pixel photosensitive area in step S104 may include:

[0074] Fill the space between adjacent light-shielding film columns 32 with colored film.

[0075] This embodiment does not limit the specific shape of each light-shielding film column 32, and may include, but is not limited to, light-shielding film columns 32 with the same width, that is, the light-shielding film columns 32 have the same width from top to bottom.

[0076] It should be noted that this embodiment essentially controls the photosensitivity of the first pixel's photosensitive area (i.e., controls the pixel's photosensitivity ratio) by controlling the exposed area of ​​the first pixel's photosensitive area, thereby achieving the high dynamic range performance requirements of the image sensor. Specific methods for controlling the exposed area of ​​the first pixel's photosensitive area can include: controlling the density of the light-shielding film pillars 32 without changing the width of the pillars; or controlling the width of the light-shielding film pillars 32 without changing the density of the pillars. Furthermore, since the remaining light-shielding film 3 on the surface of the first pixel's photosensitive area can simultaneously cover the sides of the metal grid 2 and the top surface of the metal grid 2, it can also block crosstalk light refracted by the lens structure 5 from reaching adjacent pixel sensing areas, thereby preventing the generation of crosstalk light.

[0077] The two etching methods described above involve etching away all of the light-shielding film 3 covering one or more areas of the surface of the first pixel photosensitive area, i.e., etching away a portion of the light-shielding film 3 on the surface of the first pixel photosensitive area. Alternatively, this embodiment can also etch away a portion of the thickness of the light-shielding film 3 covering the entire surface of the first pixel photosensitive area.

[0078] S104: After etching, a color filter process is performed to form a color filter on the surface of the pixel photosensitive area, and a lens structure is formed on the surface of the color filter to obtain a light-shielding semiconductor device.

[0079] It should be noted that, in this embodiment, due to the protection of the metal grid 2 by the light-shielding film 3, no depressions or protrusions will be formed in the color filter process.

[0080] This embodiment does not intend to limit the specific number of color filters, as long as each pixel photosensitive area is covered with a color filter. This embodiment does not limit the specific color of the color filter; for example, the color filter can be a red color filter 41, a green color filter 43, or a blue color filter 42. This embodiment does not limit whether the colors of the color filters in different pixel photosensitive areas are the same; this can be determined according to the actual situation. For example, different colors of color filters can be formed on the surfaces of adjacent pixel photosensitive areas. Taking the formation of four metal grids 2 as an example, this structure includes three pixel sensing areas, where the middle pixel sensing area can be the first pixel sensing area, and the two side pixel sensing areas can be the second pixel sensing areas. A blue color filter 42 can be formed on the surface of the first pixel sensing area; a red color filter 41 and a green color filter 43 can be formed on the surfaces of the two side second pixel sensing areas, respectively.

[0081] Based on the above embodiments, this application, by setting a light-shielding film on the surface of the photosensitive area of ​​the pixel that needs to be shielded, reduces the amount of light entering the photosensitive area of ​​the pixel, thereby indirectly reducing the photosensitivity of the photosensitive area of ​​the pixel and achieving a wide dynamic range effect. Simultaneously, by setting a light-shielding film on the top surface of the metal grid, it can, on the one hand, block the light path refracted by the lens structure and forming crosstalk from reaching adjacent pixel sensing areas, thereby blocking the generation of crosstalk light; on the other hand, it optimizes the overall structure of the pixel, ensuring a flat overall pixel structure, making subsequent color filter processing easier and preventing color filter depressions or protrusions, thus improving image quality.

[0082] Please refer to Figure 14 and Figure 15 The light-shielding semiconductor device provided in this application embodiment may include: a wafer 1, on the surface of which a metal grid 2 is disposed; the metal grid 2 includes a metal film layer 21 and an oxide film layer 22 disposed sequentially along the thickness direction; the area not covered by the metal grid 2 is a pixel photosensitive area; the pixel photosensitive area includes at least a first pixel photosensitive area that needs to be light-shielded.

[0083] A light-shielding film 3 is provided on the top surface of the metal grille 2; a light-shielding film 3 and a color film are provided on the surface of the photosensitive area of ​​the first pixel; a lens structure 5 is provided on the surface of the color film.

[0084] Furthermore, in this embodiment, the photosensitive area of ​​a pixel may also include a second photosensitive area that does not require light blocking; the surface of the second photosensitive area may be provided with a color filter.

[0085] It should be noted that wafer 1 in this embodiment is wafer 1 prepared by back-illuminated process, which has already formed a photodiode structure in the front-end process and has completed the bonding, thinning and other processes in the back-illuminated process.

[0086] This embodiment does not limit the specific material of the metal film layer 21. For example, the material of the metal film layer 21 can be aluminum, tungsten or other metal media.

[0087] This embodiment does not limit the specific number of metal grids 2, which can be determined according to the actual situation. For example, four metal grids 2 can be set, and the area between adjacent metal grids 2 is not covered by the metal grids 2. This area is a pixel photosensitive area. This structure includes three pixel photosensitive areas.

[0088] This embodiment does not limit the specific type of light-shielding film 3. The light-shielding film 3 can be, but is not limited to, a metal film, and the material of the metal film can be, but is not limited to, titanium oxide.

[0089] This embodiment does not limit the specific thickness of the light-shielding film 3, as long as the thickness of the light-shielding film 3 is sufficient to achieve the purpose of light shielding. For example, the thickness of the light-shielding film 3 on the surface of the metal grid 2 can be greater than 5000 Å.

[0090] This embodiment does not intend to limit the specific number of color filters, as long as each pixel photosensitive area is covered with a color filter. This embodiment does not limit the specific color of the color filter; for example, the color filter can be a red color filter 41, a green color filter 43, or a blue color filter 42. This embodiment does not limit whether the colors of the color filters in different pixel photosensitive areas are the same; this can be determined according to the actual situation, for example, the colors of the color filters on the surfaces of adjacent pixel photosensitive areas can be different. Taking the case with four metal grids 2 as an example, this structure includes three pixel sensing areas, where the middle pixel sensing area can be the first pixel sensing area, and the two side pixel sensing areas can be the second pixel sensing areas. The surface of the first pixel sensing area can be provided with a blue color filter 42; the surfaces of the two side second pixel sensing areas can be provided with a red color filter 41 and a green color filter 43, respectively.

[0091] This embodiment does not limit the specific structure of the light-shielding film 3 in the first pixel photosensitive area; for example, the following two methods can be used:

[0092] (1) Please refer to Figure 14 The light-shielding film 3 on the surface of the first pixel photosensitive area has an opening 31; the opening 31 penetrates the light-shielding film 3 along the thickness direction; the opening 31 is located in the middle area of ​​the surface of the first pixel photosensitive area; the area of ​​the opening 31 is smaller than the area of ​​the first pixel photosensitive area; the size of the opening 31 corresponds one-to-one with the photosensitivity of the pixel photosensitive area.

[0093] The opening 31 is filled with a colored film.

[0094] It should be noted that in this embodiment, the photosensitivity of the first pixel photosensitive area can be controlled by controlling the size of the opening 31 (i.e., controlling the pixel photosensitivity ratio), thereby achieving the high dynamic range performance requirements of the image sensor. Furthermore, it should be noted that since the remaining light-shielding film 3 on the surface of the first pixel photosensitive area can simultaneously cover the sides of the metal grid 2 and the sides of the top surface of the metal grid 2, it can also block the crosstalk light path refracted by the lens structure 5 from reaching adjacent pixel sensing areas, thus preventing the generation of crosstalk light.

[0095] (2) Please refer to Figure 15 Each of the multiple areas on the surface of the first pixel photosensitive area has an independent light-shielding film pillar 32; the density of the light-shielding film pillar 32 corresponds one-to-one with the photosensitivity of the pixel photosensitive area.

[0096] The space between adjacent light-shielding film columns 32 is filled with colored film.

[0097] It should be noted that in this embodiment, the photosensitivity of the first pixel photosensitive area can be controlled by adjusting the density of the light-shielding film pillars 32 (i.e., controlling the pixel photosensitivity ratio), thereby achieving the high dynamic range performance requirements of the image sensor. Furthermore, it should be noted that since the remaining light-shielding film 3 on the surface of the first pixel photosensitive area can simultaneously cover both the sides of the metal grid 2 and the sides of the top surface of the metal grid 2, it can also block crosstalk light refracted by the lens structure 5 from reaching adjacent pixel sensing areas, thus preventing the generation of crosstalk light.

[0098] In both of the above-mentioned light-shielding film 3 structures, a portion of the surface of the first pixel photosensitive area is provided with the light-shielding film 3. Alternatively, in this embodiment, the entire surface of the first pixel photosensitive area can be provided with the light-shielding film 3, and the height of the light-shielding film 3 is less than the height of the metal grid 2.

[0099] Based on the above embodiments, the light-shielding semiconductor device of this application is obtained by the above-described light-shielding semiconductor device preparation method, and also has the above-described beneficial effects.

[0100] The fabrication process of the aforementioned light-shielding semiconductor device is illustrated below with specific examples. Please refer to [link / reference]. Figures 8 to 16 The process is as follows:

[0101] 1. For example Figure 8 As shown, a back-illuminated wafer 1 is prepared, which has already formed a photodiode structure in the front-end process and has completed the bonding, thinning and other processes in the back-illuminated process.

[0102] 2. For example Figure 9 As shown, the metal grid 2 process is carried out by first depositing a metal film layer 21, the material of which is usually aluminum, tungsten, etc., and then depositing an upper oxide film layer 22 in sequence.

[0103] 3. For example Figure 10 As shown, photolithography, etching and cleaning processes are performed to form a metal grid 2, wherein the area not covered by the metal grid 2 is the photosensitive area of ​​the pixel.

[0104] 4. For example Figure 11 As shown, a light-shielding film 3 is deposited over the entire photosensitive area of ​​the pixel. The height of the light-shielding film 3 must be higher than that of the metal grid 2. The material of the light-shielding film 3 is usually titanium oxide. After deposition, a chemical mechanical polishing process is performed to ensure that the surface of the light-shielding film 3 is flat and free of bumps and depressions. After final polishing, the height is still higher than the oxide film layer 22 of the metal grid 2, and the thickness of the light-shielding film 3 is sufficient to block light (usually greater than 5000 Å).

[0105] 5. For example Figure 12 and Figure 13 As shown, photolithography and etching processes are used to etch away the light-shielding film 3 on the photosensitive areas of the pixels that do not need to be shielded from light, while the light-shielding film 3 on the metal grid 2 needs to be retained. Figure 12 As shown, a small opening smaller than the area of ​​the photosensitive area of ​​the pixel that needs to be shielded can be made above it. The size of this opening 31 controls the photosensitivity of the photosensitive area of ​​that pixel. Figure 13 As shown, the middle can also be etched into several independent light-shielding film pillars 32, and the photosensitivity of the pixel photosensitive area can be controlled by the density of the light-shielding film pillars 32.

[0106] 6. For example Figure 14 and Figure 15 As shown, for Figure 12 and Figure 13 The two embodiments of the structure are subjected to color filter processing. The resulting structure effectively avoids crosstalk, and due to the protection of the metal grid 2 by the light-shielding film 3, no depressions or protrusions are formed during the color filter process. Figure 14 The optical path diagram of the structure shown is as follows Figure 16 As shown, the light path that would normally be refracted by the lens structure 5, causing crosstalk (dashed lines in the figure), is blocked from reaching the photosensitive area of ​​the adjacent pixel due to the presence of the light-shielding film 3 on the top layer of the metal grille 2. Simultaneously, the amount of light that would normally enter the photosensitive area of ​​the light-shielding pixel is reduced due to the presence of the light-shielding film 3, indirectly decreasing the sensitivity of that pixel's photosensitive area. Furthermore, the presence of the light-shielding film 3 ensures a flat overall pixel structure, which does not affect subsequent color filter processing, resulting in a color filter without depressions or protrusions.

[0107] This document uses specific examples to illustrate the principles and implementation methods of this application. The various embodiments are progressive, with each embodiment focusing on its differences from others. Similar or identical parts between embodiments can be referred to interchangeably. The descriptions of the embodiments above are merely illustrative of the method and core ideas of this application. For those skilled in the art, various improvements and modifications can be made to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this application.

[0108] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

Claims

1. A method for fabricating a light-shielding semiconductor device, characterized in that, include: A metal grid process is performed on the surface of a wafer to form a metal grid; the metal grid includes a metal film layer and an oxide film layer arranged sequentially along the thickness direction. The area not covered by the metal grille is the photosensitive area of ​​a pixel; the photosensitive area of ​​a pixel includes at least the first photosensitive area of ​​a pixel that needs to be shielded from light. A light-shielding film is deposited on the surface of the wafer having the metal grid, and the light-shielding film is made higher than the metal grid; A portion of the light-shielding film on the surface of the photosensitive area of ​​the first pixel is etched away, while the light-shielding film on the top surface of the metal grille is retained; After etching is completed, a color filter process is performed to form a color filter on the surface of the photosensitive area of ​​the pixel, and a lens structure is formed on the surface of the color filter to obtain a light-shielding semiconductor device.

2. The method for fabricating a light-shielding semiconductor device according to claim 1, characterized in that, After depositing a light-shielding film on the wafer surface having the metal grid, such that the light-shielding film is higher than the metal grid, the process further includes: The surface of the light-shielding film is subjected to a chemical mechanical polishing process, and the polished light-shielding film is made to be higher than the metal grid.

3. The method for fabricating a light-shielding semiconductor device according to claim 2, characterized in that, The thickness of the light-shielding film on the surface of the metal grid after grinding is greater than 5000 Å.

4. The method for fabricating a light-shielding semiconductor device according to claim 1, characterized in that, The photosensitive area of ​​a pixel also includes a second photosensitive area of ​​a pixel that does not require light blocking; Accordingly, after depositing a light-shielding film on the wafer surface having the metal grid, and making the light-shielding film higher than the metal grid, the method further includes: The light-shielding film on the surface of the photosensitive area of ​​the second pixel is etched away; Accordingly, forming a color film on the surface of the photosensitive area of ​​the pixel includes: The color filter is formed on the surface of the second pixel photosensitive area and on the surface of the first pixel photosensitive area.

5. The method for fabricating a light-shielding semiconductor device according to any one of claims 1 to 4, characterized in that, The portion of the light-shielding film that is etched away from the surface of the photosensitive area of ​​the first pixel includes: The light-shielding film in the middle area of ​​the surface of the first pixel photosensitive area is etched away to form an opening; the opening penetrates the light-shielding film along the thickness direction; the area of ​​the opening is smaller than the area of ​​the first pixel photosensitive area; the size of the opening corresponds one-to-one with the photosensitivity of the first pixel photosensitive area; Accordingly, forming a color film on the surface of the photosensitive area of ​​the pixel includes: The color filter is filled into the opening.

6. The method for fabricating a light-shielding semiconductor device according to any one of claims 1 to 4, characterized in that, The portion of the light-shielding film that is etched away from the surface of the photosensitive area of ​​the first pixel includes: The light-shielding film in multiple areas on the surface of the first pixel photosensitive area is etched away to form multiple independent light-shielding film pillars; the density of the light-shielding film pillars corresponds one-to-one with the photosensitivity of the first pixel photosensitive area; Accordingly, forming a color film on the surface of the photosensitive area of ​​the pixel includes: The colored film is filled between adjacent light-shielding film columns.

7. A light-shielding semiconductor device, characterized in that, include: A wafer, the surface of which is provided with a metal grid; the metal grid includes a metal film layer and an oxide film layer arranged sequentially along the thickness direction; the area not covered by the metal grid is a pixel photosensitive area; the pixel photosensitive area includes at least a first pixel photosensitive area that needs to be shielded from light. The top surface of the metal grille is provided with a light-shielding film; the surface of the photosensitive area of ​​the first pixel is provided with the light-shielding film and a color filter; the surface of the color filter is provided with a lens structure.

8. The light-shielding semiconductor device according to claim 7, characterized in that, The photosensitive area of ​​the pixel also includes a second photosensitive area that does not require light blocking; the color film is disposed on the surface of the second photosensitive area.

9. The light-shielding semiconductor device according to claim 7 or 8, characterized in that, The light-shielding film on the surface of the first pixel photosensitive area has an opening; the opening extends through the light-shielding film along the thickness direction; the opening is located in the middle region of the surface of the first pixel photosensitive area; the area of ​​the opening is smaller than the area of ​​the first pixel photosensitive area; the size of the opening corresponds one-to-one with the photosensitivity of the pixel photosensitive area. The opening is filled with the color filter.

10. The light-shielding semiconductor device according to claim 7 or 8, characterized in that, Each of the multiple areas on the surface of the first pixel photosensitive area is provided with an independent light-shielding film pillar; the density of the light-shielding film pillars corresponds one-to-one with the photosensitivity of the pixel photosensitive area; The colored film is filled between adjacent light-shielding film columns.

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