Backside illuminated image sensor and method of making the same

Abstract

The application provides a back-illuminated image sensor and a manufacturing method thereof, and the method comprises the following steps: providing a substrate, the substrate comprises a pixel area and a non-pixel area, and a plurality of pixel electrodes located in the pixel area and a plurality of metal interconnection layers located in the non-pixel area are formed in the substrate; forming a deep trench isolation structure in the substrate of the pixel area, forming a metal grid on the substrate of the pixel area, the metal grid is located above the deep trench isolation structure, the deep trench isolation structure is located above the pixel electrode, and the metal grid close to the non-pixel area extends to the non-pixel area; forming a metal pad in the substrate of the non-pixel area, the metal pad is connected with the metal interconnection layer, and the metal pad is connected with the metal grid extending to the non-pixel area. According to the application, the metal grid is connected with the metal pad, so that a grounding hole is not needed to ground the metal grid, the use of a mask is reduced, the process steps are reduced, and the process cost is saved.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to a back-illuminated image sensor and its fabrication method. Background Technology

[0002] CMOS (Complementary Metal Oxide Semiconductor) image sensors exhibit varying degrees of electronic and optical crosstalk among their pixels. Electronic crosstalk is caused by electrons diffusing or drifting into other pixels, while optical crosstalk is primarily caused by light incident on adjacent pixels. To mitigate optical crosstalk, existing back-illuminated image sensor technologies typically employ the addition of a metal grid.

[0003] In existing back-illuminated image sensors, aluminum is typically used as the metal grid material, and the aluminum and silicon substrate are connected through a dedicated grounding via to achieve metal grounding. However, this requires an additional mask to fabricate the grounding via structure, increasing the number of process steps and costs.

[0004] Figure 1 This is a schematic diagram of the structure of a back-illuminated image sensor, as shown below. Figure 1 As shown, the back-illuminated image sensor includes: a substrate 10, which contains a pixel region A and a non-pixel region B; a pixel electrode 11 and a metal interconnect layer 12 located within the substrate 10; the pixel electrode 11 being located in the pixel region A; and the metal interconnect layer 12 being located in the non-pixel region B. A deep trench isolation structure 13 and a metal pad 14 extend from the surface of the substrate 10 into the substrate 10. The deep trench isolation structure 13 is located above the pixel electrode 11 but not in contact with it. The metal pad 14 is located above the metal interconnect layer 12 and connected to it. A metal grid 15 is formed on the substrate 10 above the deep trench isolation structure 13. To connect the metal grid 15 to the substrate 10 for grounding, a grounding hole needs to be formed within the substrate 10 and then filled with metal to form a grounding hole structure 16. Therefore, an additional mask is required to form the grounding hole, thus increasing the process steps and cost. Summary of the Invention

[0005] The purpose of this invention is to provide a back-illuminated image sensor and its manufacturing method, so as to reduce the number of process steps and save process costs.

[0006] To address the aforementioned technical problems, this invention provides a method for manufacturing a back-illuminated image sensor, comprising the following steps:

[0007] A substrate is provided, the substrate includes a pixel region and a non-pixel region, and a plurality of pixel electrodes located in the pixel region and a plurality of metal interconnection layers located in the non-pixel region are formed in the substrate;

[0008] A deep trench isolation structure is formed in the substrate in the pixel region, a metal grid is formed on the substrate in the pixel region, the metal grid is located above the deep trench isolation structure, the deep trench isolation structure is located above the pixel electrodes, and the metal grid near the non-pixel region extends to the non-pixel region; and

[0009] A metal pad is formed in the substrate in the non-pixel region, the metal pad is connected with the metal interconnection layers, and the metal pad is connected with the metal grid extending to the non-pixel region.

[0010] Optionally, the method for forming the deep trench isolation structure in the substrate in the pixel region includes:

[0011] The substrate in the pixel region is etched to form a plurality of deep isolation trenches, each of the deep isolation trenches is located above each of the pixel electrodes, and the deep isolation trenches correspond to the pixel electrodes one by one;

[0012] A metal material is filled in the deep isolation trenches to form the deep trench isolation structure.

[0013] Optionally, after the deep isolation trenches are formed and before the metal material is filled, the method further includes:

[0014] A dielectric layer and a first protective layer are sequentially formed, the dielectric layer covers the sidewalls and bottom of the deep isolation trenches and covers the substrate, and the first protective layer covers the sidewalls and bottom of the deep isolation trenches.

[0015] Optionally, the method for forming the metal grid on the substrate in the pixel region includes:

[0016] A second protective layer and a metal grid material layer are sequentially formed, the second protective layer covers the dielectric layer and the deep trench isolation structure, and the metal grid material layer covers the second protective layer.

[0017] The metal grid material layer is etched to form a metal grid, the metal grid is located above the deep trench isolation structure, and the metal grid near the non-pixel region extends to the non-pixel region; and

[0018] A third protective layer is formed, the third protective layer covers the metal grid and the second protective layer.

[0019] Optionally, the first protective layer, the second protective layer and the third protective layer are made of the same material, and the dielectric layer is made of a high dielectric constant material.

[0020] Optionally, the method for forming the metal pad in the non-pixel region of the substrate comprises:

[0021] performing a first etching on the substrate in the non-pixel region to form a first opening, the first opening is above the metal interconnection layer and does not expose the metal interconnection layer, and a sidewall of the first opening exposes the metal grid extending to the non-pixel region;

[0022] performing a second etching on the substrate in the non-pixel region to form at least two second openings in the first opening, each of the second openings exposes part of the metal interconnection layer, and one sidewall of the second opening near the pixel region is connected with the sidewall of the first opening in a direction perpendicular to the substrate;

[0023] forming a metal material layer, the metal material layer covers the substrate, fills the second openings and fills the sidewall and bottom of the first opening, and the metal material layer is connected with the metal grid exposed by the sidewall of the first opening; and

[0024] etching the metal material layer to form a metal pad in the second openings and the first opening, and part of the metal material layer remains on the sidewall of the first opening near the pixel region, the metal pad is connected with the metal grid through the metal material layer.

[0025] Optionally, after the first opening is formed and before the second opening is formed, the method further comprises:

[0026] forming a fourth protective layer, the fourth protective layer covers the sidewall and bottom of the first opening.

[0027] Optionally, when the second etching is performed on the substrate in the non-pixel region to form the second opening, the method further comprises: etching to remove the fourth protective layer on the sidewall of the first opening near the pixel region to expose the metal grid extending to the non-pixel region.

[0028] Optionally, the metal material layer is formed by a physical vapor deposition method, and the thickness of the metal material layer on the sidewall of the first opening near the pixel region is greater than the thickness of the metal material layer on the other sidewall.

[0029] Correspondingly, the application also provides a back-illuminated image sensor made by the method for manufacturing a back-illuminated image sensor.

[0030] The back-illuminated image sensor and the manufacturing method thereof provided by the application, wherein the substrate comprises a pixel area and a non-pixel area, and a plurality of pixel electrodes in the pixel area and a plurality of metal interconnection layers in the non-pixel area are formed in the substrate; a deep trench isolation structure is formed in the substrate in the pixel area, a metal grid is formed on the substrate in the pixel area, the metal grid is above the deep trench isolation structure, the deep trench isolation structure is above the pixel electrode, and the metal grid extending to the non-pixel area is close to the non-pixel area; a metal pad is formed in the substrate in the non-pixel area, the metal pad is connected with the metal interconnection layer, and the metal pad is connected with the metal grid extending to the non-pixel area, so that a grounding hole is not needed to be additionally manufactured to ground the metal grid, the use of a mask is reduced, the process steps are reduced, and the process cost is saved.

[0031] In addition, the metal pad is connected with the metal grid extending to the non-pixel area, the metal pad connected with the metal grid can be grounded or connected with a potential, so that the potential of the metal grid can be adjusted, and the performance of the back-illuminated image sensor is improved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Those skilled in the art should understand that the drawings provided are used to better understand the application, and do not constitute any limitation on the scope of the application.

[0033] Figure 1 Fig. 1 is a structural schematic diagram of a back-illuminated image sensor.

[0034] Figure 2 Fig. 5 is a flow chart of a manufacturing method of a back-illuminated image sensor provided by an embodiment of the application.

[0035] Figures 3 to 8 Fig. 6 is a structural schematic diagram of each step of a manufacturing method of a back-illuminated image sensor provided by an embodiment of the application.

[0036] Figure 9 Fig. 7 is a top view of a back-illuminated image sensor provided by an embodiment of the application.

[0037] Reference signs:

[0038] Figure 1 10-substrate; 11-pixel electrode; 12-metal interconnection layer; 13-deep trench isolation structure; 14-metal pad; 15-metal grid; 16-grounding hole structure.

[0039] Figures 3 to 8100 - substrate; 101 - pixel electrode; 102 - metal interconnection layer; 103 - deep isolation trench; 104 - dielectric layer; 105 - first protective layer; 106 - deep trench isolation structure; 107 - second protective layer; 108 - metal grid material layer; 109 - metal grid; 110 - third protective layer; 111 - first opening; 112 - fourth protective layer; 113 - second opening; 114 - metal material layer; 115 - metal pad. DETAILED DESCRIPTION

[0040] In order to make the objects, advantages and features of the present application clearer, the following further describes the present application in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are very simplified and not drawn to scale, and are only used to facilitate and clarify the purpose of describing the embodiments of the present application. In addition, the structures shown in the drawings are often a part of the actual structures. In particular, the emphasis shown in each drawing is different, and sometimes different scales are used.

[0041] As used in the present application, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise. The term "at least two" is generally employed in its sense including "two or more" unless the content clearly dictates otherwise. In addition, the terms "first," "second," "third," are used only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first," "second," "third" can explicitly or implicitly include one or at least two of the features, unless the content clearly indicates otherwise.

[0042] Figure 2 is a flowchart of a manufacturing method of a back-illuminated image sensor provided by an embodiment of the present application.

[0043] As shown in Figure 2 the manufacturing method of the back-illuminated image sensor includes the following steps:

[0044] S1: providing a substrate, the substrate including a pixel region and a non-pixel region, and the substrate having a plurality of pixel electrodes formed in the pixel region and a plurality of metal interconnection layers formed in the non-pixel region;

[0045] S2: forming a deep trench isolation structure in the substrate in the pixel region, and forming a metal grid on the substrate in the pixel region, the metal grid being located above the deep trench isolation structure, the deep trench isolation structure being located above the pixel electrodes, and the metal grid near the non-pixel region extending to the non-pixel region;

[0046] S3: forming a metal pad in the substrate in the non-pixel region, the metal pad being connected with the metal interconnection layer, and the metal pad being connected with the metal grid extending to the non-pixel region.

[0047] Figures 3 to 8 is a schematic structural diagram of each step of a manufacturing method of a back-illuminated image sensor provided by an embodiment of the present application, Figure 9 is a top view of a back-illuminated image sensor provided by an embodiment of the present application. Next, the manufacturing method of the back-illuminated image sensor provided by an embodiment of the present application will be described in detail in combination with Figure 2 and Figures 3 to 9 the manufacturing method of the back-illuminated image sensor provided by an embodiment of the present application.

[0048] In step S1, referring to FIG. 1, a substrate 100 is provided, the substrate 100 comprises a pixel region A and a non-pixel region B, and the substrate 100 is formed with a plurality of pixel electrodes 101 in the pixel region A and a plurality of metal interconnection layers 102 in the non-pixel region B. Figure 3

[0049] The material of the substrate 100 can be silicon, germanium, germanium silicon, silicon carbide, gallium arsenide or indium gallium, and can also be silicon on insulator or germanium on insulator. In this embodiment, the material of the substrate 100 is preferably silicon.

[0050] The substrate 100 comprises the pixel region A and the non-pixel region B, and the non-pixel region B surrounds the pixel region A (see FIG. 1). The substrate 100 in the pixel region A is formed with a plurality of pixel electrodes 101, and the substrate 100 in the non-pixel region B is formed with a plurality of metal interconnection layers 102. Figure 9 Figures 3 to 8 Only one of the metal interconnection layers 102 is shown in FIG. 1. The pixel electrodes 101 and the metal interconnection layers 102 can be formed by using a manufacturing method known to those skilled in the art, which will not be described herein.

[0051] In step S2, referring to FIG. 2, a deep trench isolation structure 106 is formed in the substrate 100 in the pixel region A, and a metal grid 109 is formed on the substrate 100 in the pixel region A, the metal grid 109 being located above the deep trench isolation structure 106, the deep trench isolation structure 106 being located above the pixel electrodes 101, and the metal grid 109 extending to the non-pixel region B near the non-pixel region B. Figure 5 Specifically, first, referring to FIG. 2, a deep trench isolation structure 106 is formed in the substrate 100 in the pixel region A.

[0052] Figure 3 ​​​As shown, the substrate 100 is etched to form a plurality of deep isolation trenches 103, each of the deep isolation trenches 103 is located above each of the pixel electrodes 101, and the deep isolation trenches 103 correspond to the pixel electrodes 101 one by one. As an example, a photoresist layer (not shown) can be first coated on the substrate 100, the photoresist layer is exposed and developed to form a patterned photoresist layer, and the patterned photoresist layer exposes the areas of the substrate 100 where the deep isolation trenches 103 are to be formed; then, the substrate 100 is etched to a partial thickness to form a plurality of the deep isolation trenches 103, the deep isolation trenches 103 are located above the pixel electrodes 101 and do not expose the pixel electrodes 101; finally, the patterned photoresist layer is removed.

[0053] Next, please refer to Figure 4 As shown, a dielectric layer 104 and a first protective layer 105 are sequentially formed, the dielectric layer 104 covers the sidewalls and bottom of the deep isolation trenches 103 and covers the substrate 100, and the first protective layer 105 covers the sidewalls and bottom of the deep isolation trenches 103. Then, a metal material is filled in the deep isolation trenches 103 to form a deep trench isolation structure 106. In this embodiment, the material of the dielectric layer 104 includes a high dielectric constant material, such as hafnium oxide, aluminum oxide, or tantalum oxide, the material of the first protective layer 105 includes silicon oxide, and the metal material includes aluminum or tungsten.

[0054] Next, please continue to refer to Figure 4 As shown, a second protective layer 107 is formed on the substrate 100, the second protective layer 107 covers the dielectric layer 104 and the deep trench isolation structure 106. Then, a metal grid material layer 108 is formed, the metal grid material layer 108 covers the second protective layer 107. The material of the second protective layer 107 is the same as the material of the first protective layer 104, the material of the second protective layer 107 includes silicon oxide, and the material of the metal grid material layer 108 includes aluminum.

[0055] Next, please refer to Figure 5 As shown, the metal grid material layer 108 is etched to form a metal grid 109, the metal grid 109 is located above the deep trench isolation structure 106, and the metal grid 109 near the non-pixel area B extends to the non-pixel area B. Then, a third protective layer 110 is formed, the third protective layer 110 covers the metal grid 109 and the second protective layer 107. The material of the third protective layer 107 is the same as the material of the second protective layer 107 and the first protective layer 104, for example, the material of the third protective layer 107 includes silicon oxide.

[0056] In step S3, please refer to Figure 8 As shown in the figure, a metal pad 115 is formed in the substrate 100 of the non-pixel region B, the metal pad 115 is connected with the metal interconnection layer 102, and the metal pad 115 is connected with the metal grid 109 extending to the non-pixel region B.

[0057] First, please refer to Figure 6 As shown in the figure, the substrate 100 of the non-pixel region B is etched for the first time to form a first opening 111, the first opening 111 is located above the metal interconnection layer 102 and does not expose the metal interconnection layer 102, and the sidewall of the first opening 111 exposes the metal grid 109 extending to the non-display region B. For example, first, a photoresist layer is formed on the substrate 100, the photoresist layer is exposed and developed to form a patterned photoresist layer, and the patterned photoresist layer exposes the region of the substrate 100 where the metal pad is to be formed; then, using the patterned photoresist layer as a mask, etching a portion of the thickness of the substrate 100 to form the first opening 111; finally, removing the patterned photoresist layer.

[0058] Next, please continue to refer to Figure 6 As shown in the figure, a fourth protective layer 112 is formed, which covers the sidewall and bottom of the first opening 111, and the material of the fourth protective layer 112 includes silicon oxide.

[0059] Next, please continue to refer to Figure 6 As shown in the figure, the substrate 100 of the non-pixel region B is etched for the second time to form at least two second openings 113 in the first opening 111, Figure 6 Only two second openings 113 are shown in the figure, each of the second openings 113 exposes a portion of the metal interconnection layer 102, and one of the sidewalls of the second opening 113 near the pixel region A overlaps with the sidewall of the first opening 111. For example, a photoresist layer is formed on the substrate 100, the photoresist layer covers the substrate 100 and fills the first opening 111; then, the photoresist layer is exposed and developed to form a patterned photoresist layer, and the patterned photoresist layer exposes the region of the substrate 100 in the first opening where the second opening is to be formed; then, using the patterned photoresist layer as a mask, etching the substrate 100 to expose the metal interconnection layer 102 to form a plurality of second openings 113, wherein the sidewall of one of the second openings 113 near the pixel region A is connected with the sidewall of the first opening 111 in a direction perpendicular to the substrate 100, and the direction perpendicular to the substrate 100 means Figure 6The vertical direction in the substrate 100, i.e. etching the substrate 100 at the bottom of the first opening 111 along the sidewall of the first opening 111 close to the pixel region A, forms a second opening 113, and the fourth protective layer 112 on the sidewall of the first opening 111 close to the pixel region A is etched and removed.

[0060] Next, as shown in FIG. 7, a metal material layer 114 is formed, covering the substrate 100, filling the second opening 113 and the sidewall and bottom of the first opening 111, and the metal material layer 114 is connected with the metal grid 109 exposed by the sidewall of the first opening 111. The material of the metal material layer 114 includes aluminum, and the metal material layer 114 can be formed by physical vapor deposition. Due to the positional relationship between the first opening 111 and the second opening 113, the thickness of the metal material layer 114 on the sidewall of the first opening 111 close to the pixel region A is greater than the thickness of the metal material layer 114 on the other sidewall.

[0061] Finally, as shown in FIG. 8, the metal material layer 114 is etched to form a metal pad 115 in the second opening 113 and the first opening 111, and part of the metal material layer 114 remains on the sidewall of the first opening 111 close to the pixel region A, and the metal pad 115 is connected with the metal grid 109 through the metal material layer 114. Figure 8

[0062] The back-illuminated image sensor and the manufacturing method thereof provided by the present application, the substrate 100 includes a pixel region A and a non-pixel region B, and a plurality of pixel electrodes 101 located in the pixel region A and a plurality of metal interconnection layers 102 located in the non-pixel region B are formed in the substrate 100; a deep trench isolation structure 105 is formed in the substrate 100 in the pixel region A, a metal grid 109 is formed on the substrate 100 in the pixel region A, the metal grid 109 is located above the deep trench isolation structure 105, the deep trench isolation structure 105 is located above the pixel electrode 101, and the metal grid 109 close to the non-pixel region A extends to the non-pixel region B; a metal pad 115 is formed in the substrate 100 in the non-pixel region B, the metal pad 115 is connected with the metal interconnection layer 102, and the metal pad 115 is connected with the metal grid 109 extending to the non-pixel region B, so that a grounding hole is not needed to be additionally manufactured to ground the metal grid, the use of masks is reduced, the process steps are reduced, and the process cost is saved.

[0063] In addition, as shown in FIG. 9, the metal pad 115 is connected with the metal grid 109 through the metal material layer 114, and the metal pad 115 is connected with the metal interconnection layer 102. Figure 9 ​As shown, a plurality of metal pads 115 are formed in the non-pixel region B, and the metal grid 109 can be connected to one or more of the metal pads 115. The metal pad 115 connected to the metal grid 109 can be grounded or connected to a potential, so that the potential of the metal grid 109 can be adjusted to improve the performance of the back-illuminated image sensor.

[0064] Accordingly, the present application also provides a back-illuminated image sensor manufactured by the method as described above. Please refer to Figure 8 With Figure 9 As shown, the back-illuminated image sensor comprises:

[0065] a substrate 100 comprising a pixel region A and a non-pixel region B, and a plurality of pixel electrodes 101 formed in the pixel region A and a plurality of metal interconnection layers 102 formed in the non-pixel region B;

[0066] a deep trench isolation structure 106 formed in the substrate 100 in the pixel region A, and the deep trench isolation structure 106 is above the pixel electrode 101;

[0067] a metal grid 109 formed on the substrate 100 in the pixel region A, and the metal grid 109 is above the deep trench isolation structure 106, and the metal grid 109 near the non-pixel region B extends to the non-pixel region B;

[0068] a metal pad 115 formed in the substrate 100 in the non-pixel region B, and the metal pad 115 is connected to the metal grid 109 extending to the non-pixel region B.

[0069] The above description is only a description of the preferred embodiments of the present application, and is not any limitation on the scope of the present application. Any modification or change made by a person of ordinary skill in the art according to the above disclosure is within the protection scope of the claims.

Claims

1. A method for manufacturing a back-illuminated image sensor, characterized in that, Includes the following steps: A substrate is provided, the substrate comprising a pixel region and a non-pixel region, and a plurality of pixel electrodes located in the pixel region and a plurality of metal interconnect layers located in the non-pixel region are formed therein; A deep trench isolation structure is formed in the substrate of the pixel area, and a metal grid is formed on the substrate of the pixel area. The metal grid is located above the deep trench isolation structure, the deep trench isolation structure is located above the pixel electrode, and the metal grid near the non-pixel area extends into the non-pixel area. as well as A metal pad is formed in the substrate in the non-pixel area, the metal pad is connected to the metal interconnect layer, and the metal pad is connected to the metal grid extending to the non-pixel area; The method for forming a metal grid on the substrate in the pixel region includes: The substrate in the non-pixel region is etched for the first time to form a first opening, the first opening being located above the metal interconnect layer and not exposing the metal interconnect layer, and the sidewall of the first opening exposing the metal grille extending into the non-pixel region; The substrate in the non-pixel area is etched a second time to form at least two second openings in the first opening. Each second opening exposes a portion of the metal interconnect layer, and one sidewall of the second opening near the pixel area is connected to the sidewall of the first opening in a direction perpendicular to the substrate. A metal material layer is formed, which covers the substrate, fills the second opening, and fills the sidewalls and bottom of the first opening, and the metal material layer is connected to the metal grid exposed on the sidewalls of the first opening; and The metal material layer is etched to form metal pads in the second opening and the first opening, and a portion of the metal material layer remains on the sidewall of the first opening near the pixel area. The metal pads are connected to the metal grid through the metal material layer.

2. The method for manufacturing a back-illuminated image sensor as described in claim 1, characterized in that, A method for forming a deep trench isolation structure within the substrate of the pixel region includes: The substrate of the pixel area is etched to form a plurality of deep isolation trenches, each of which is located above each pixel electrode and corresponds one-to-one with the pixel electrode. Metal material is filled into the deep isolation trench to form a deep trench isolation structure.

3. The method for manufacturing a back-illuminated image sensor as described in claim 2, characterized in that, After forming the deep isolation trench and before filling it with the metallic material, the method further includes: A dielectric layer and a first protective layer are formed sequentially. The dielectric layer covers the sidewalls and bottom of the deep isolation trench and covers the substrate. The first protective layer covers the sidewalls and bottom of the deep isolation trench.

4. The method for manufacturing a back-illuminated image sensor as described in claim 3, characterized in that, A method for forming a metal grid on the substrate of the pixel region includes: A second protective layer and the metal grid material layer are formed sequentially, the second protective layer covering the dielectric layer and the deep trench isolation structure, and the metal grid material layer covering the second protective layer; The metal grid material layer is etched to form a metal grid, the metal grid being located above the deep trench isolation structure and extending into the non-pixel area; and A third protective layer is formed, which covers the metal grille and the second protective layer.

5. The method for manufacturing a back-illuminated image sensor as described in claim 4, characterized in that, The first protective layer, the second protective layer, and the third protective layer are made of the same material, and the dielectric layer is made of a material with a high dielectric constant.

6. The method for manufacturing a back-illuminated image sensor as described in claim 1, characterized in that, After forming the first opening and before forming the second opening, the method further includes: A fourth protective layer is formed, which covers the sidewalls and bottom of the first opening.

7. The method for manufacturing a back-illuminated image sensor as described in claim 6, characterized in that, When the substrate in the non-pixel region is etched a second time to form the second opening, the method further includes: etching away the fourth protective layer on the sidewall of the first opening near the pixel region, exposing the metal grille extending to the non-pixel region.

8. The method for manufacturing a back-illuminated image sensor as described in claim 7, characterized in that, The metal material layer is formed by physical vapor deposition, wherein the thickness of the metal material layer on the sidewall of the first opening near the pixel region is greater than the thickness of the metal material layer on the other sidewall.

9. A back-illuminated image sensor, characterized in that, It is manufactured using the method for manufacturing a back-illuminated image sensor as described in any one of claims 1 to 8.

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