Method for improving peripheral degumming of pixel region of CIS (Contact Image Sensor) and photoresist pattern structure

Abstract

The invention provides a method for improving degumming of the periphery of a pixel region of a CIS (Contact Image Sensor) and a photoresist pattern structure, and the method comprises the steps: carrying out the ion implantation technology of the pixel region through taking a patterned photoresist layer as a mask, so as to form an isolation region in the pixel region, the pattern of the patterned photoresist layer comprises a grid-type opening pattern, a plurality of I-type opening patterns and four V-type opening patterns, the grid-type opening pattern is located above the internal region, the V-type opening patterns are located above four corners of the peripheral region, the I-type opening patterns are located above the peripheral region and are communicated with the end parts of the grid-type opening pattern, and the V-type opening patterns are communicated with the end parts of the V-type opening patterns. According to the invention, the pattern design of the outermost periphery of the photoresist layer is optimized, so that the photoresist layer at the boundary of the pixel region can be buffered to a certain extent in the photoetching development process, the outermost periphery of the patterned photoresist layer is prevented from collapsing, falling off and stripping, the stability of ion implantation of the isolation region is ensured, and the reliability of the isolation region is improved. Therefore, the pixel performance and quality of the image sensor are improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, specifically to a method for improving the removal of photoresist from the periphery of the pixel area in a CIS and a photoresist pattern structure. Background Technology

[0002] The pixel size of an image sensor (CIS) is determined by the structure and size of the photodiode (PD). A PD is generally formed by its N-type electron collection region and P-type isolation region. In traditional non-stacked CIS, the PD isolation region (mesh isolation region) is formed by ion implantation of the substrate using a mesh-shaped photoresist formed by photolithography as a mask. The mesh isolation region completely isolates the N-type electron collection region of the PD.

[0003] However, as the pixels of high-pixel image sensors gradually become smaller, the challenges to the photolithography conditions of non-stacked small-sized PD structures are constantly increasing. The smaller the pixel size, the smaller the linewidth and grid space of the mesh photoresist will be. The outermost edge of this high aspect ratio mesh photoresist is prone to peeling and detachment during exposure, which seriously restricts the pixel performance and quality of image sensors. Summary of the Invention

[0004] This application provides a method and photoresist pattern structure to improve the periphery of the pixel area of ​​a CIS, which can solve the problem that the outermost edge of a high aspect ratio mesh-like photoresist is prone to peeling and detachment during exposure, thus severely restricting the pixel performance and quality of the image sensor.

[0005] On one hand, embodiments of this application provide a method for improving the delamination around the pixel area of ​​a CIS, including:

[0006] A substrate is provided, the substrate comprising at least a pixel region, the pixel region comprising: a peripheral region and an internal region surrounded by the peripheral region;

[0007] A photoresist layer is coated on the substrate;

[0008] The pattern on the photomask is transferred onto the photoresist layer using a photolithography process to form a patterned photoresist layer above the pixel area. The patterned photoresist layer includes a grid-shaped opening pattern, multiple I-shaped opening patterns, and four V-shaped opening patterns. The grid-shaped opening pattern is located above the inner region, the V-shaped opening patterns are located above the four corners of the outer region, and the I-shaped opening patterns are located above the outer region and connected to the ends of the grid-shaped opening pattern.

[0009] Using the patterned photoresist layer as a mask, an ion implantation process is performed on the pixel region to form an isolation region in the pixel region;

[0010] Remove the patterned photoresist layer.

[0011] Optionally, in the method for improving the descaling around the pixel area of ​​the CIS, the opening angle of the V-shaped opening pattern is 90°.

[0012] Optionally, in the method for improving the delamination around the pixel area of ​​the CIS, the opening of any one of the V-shaped opening patterns is directly opposite any one of the four corners of the peripheral area.

[0013] Optionally, in the method for improving the delamination around the pixel area of ​​CIS, the grid-type opening pattern includes a plurality of arrayed square-shaped opening pattern units.

[0014] Optionally, in the method for improving the delamination around the pixel area of ​​CIS, the width dimension of the U-shaped opening pattern unit along the Y direction is smaller than the width dimension of the I-shaped opening pattern along the Y direction.

[0015] Optionally, in the method for improving the delamination around the pixel area of ​​the CIS, the width dimension of the I-shaped opening pattern along the Y direction is twice the width dimension of the U-shaped opening pattern unit along the Y direction.

[0016] Optionally, in the method for improving the removal of photoresist from the pixel area of ​​the CIS, the ratio of the thickness of the photoresist layer to the maximum critical size of the photoresist unit of the island-shaped structure covering the inner region is greater than 10:1; the ratio of the thickness of the photoresist layer to the maximum critical size of the V-shaped structure photoresist unit covering the outer region is less than 10:1; and the ratio of the thickness of the photoresist layer to the maximum critical size of the elongated photoresist unit covering the outer region is less than 10:1.

[0017] On the other hand, this application embodiment also provides a photoresist pattern structure, including: a photoresist layer, a grid-type opening pattern, an I-type opening pattern, and a V-type opening pattern, wherein the grid-type opening pattern, the I-type opening pattern, and the V-type opening pattern are all located in the photoresist layer, the grid-type opening pattern is located above the inner region of the pixel area, the V-type opening pattern is located above the four corners of the outer region of the pixel area, and the I-type opening pattern is located above the outer region of the pixel area and is connected to the end of the grid-type opening pattern;

[0018] The photoresist pattern structure serves as a mask for the ion implantation process of the pixel area at the bottom of the photoresist pattern structure. The grid-shaped opening pattern, the I-shaped opening pattern, and the V-shaped opening pattern serve as ion implantation windows for the pixel area, thereby forming an isolation region in the pixel area through ion implantation.

[0019] The technical solution of this application has at least the following advantages:

[0020] This application utilizes a patterned photoresist layer as a mask to perform ion implantation on the pixel region to form an isolation region within the pixel region. The patterned photoresist layer includes a grid-shaped opening pattern, multiple I-shaped opening patterns, and four V-shaped opening patterns. The grid-shaped opening patterns are located above the inner region, the V-shaped opening patterns are located above the four corners of the outer region, and the I-shaped opening patterns are located above the outer region and connected to the ends of the grid-shaped opening patterns. By optimizing the outermost pattern design of the photoresist layer, this application provides a buffer for the photoresist layer at the pixel region boundary during the photolithography and development process. This prevents the outermost edge of the patterned photoresist layer from collapsing, detaching, or peeling off, thus solving the problem of peeling and detachment that easily occurs during exposure of high aspect ratio grid-shaped photoresists. This ensures the stability of ion implantation in the isolation region, thereby improving the pixel performance and quality of the image sensor. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a flowchart of a method for improving the delamination around the pixel area of ​​a CIS according to an embodiment of the present invention;

[0023] Figure 2 This is a top view of the pixel area according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the photoresist pattern structure according to an embodiment of the present invention;

[0025] The reference numerals in the attached figures are explained as follows:

[0026] 10- Patterned photoresist layer, 11- Mesh-shaped opening pattern, 12- I-shaped opening pattern, 13- V-shaped opening pattern, 20- Pixel area, 21- Inner area, 22- Outer area, 31- Island-shaped photoresist unit, 32- V-shaped photoresist unit, 33- Strip-shaped photoresist unit, 34- Square photoresist unit. Detailed Implementation

[0027] The technical solutions of this application 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 this application. 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.

[0028] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0031] This application provides a method for improving the removal of adhesive residue around the pixel area of ​​a CIS (CMOS Image Sensor). (Refer to...) Figure 1 , Figure 1 This is a flowchart of a method for improving the periphery adhesive removal of the pixel area in a CIS according to an embodiment of the present invention. The method for improving the periphery adhesive removal of the pixel area in a CIS includes:

[0032] First, perform step S1: Refer to Figure 2 , Figure 2This is a top view of a pixel region according to an embodiment of the present invention. A substrate is provided, the substrate including at least a pixel region 20, the pixel region 20 including: a peripheral region 22 and an inner region 21 surrounded by the peripheral region 22.

[0033] Then, step S2 is performed: a photoresist layer is coated on the substrate.

[0034] Next, proceed to step S3: (Refer to...) Figure 3 , Figure 3 This is a schematic diagram of the photoresist pattern structure according to an embodiment of the present invention. Through photolithography, the pattern on the photomask is transferred onto the photoresist layer to form a patterned photoresist layer 10 above the pixel area. The pattern of the patterned photoresist layer includes: a grid-type opening pattern 11, a plurality of I-type opening patterns 12, and four V-type opening patterns 13. The grid-type opening pattern 11 is located above the inner region 21, the V-type opening patterns 13 are located above the four corners of the outer region 22, and the I-type opening patterns 12 are located above the outer region 22 and are connected to the ends of the grid-type opening pattern 11.

[0035] Preferably, the opening of any one of the V-shaped opening patterns 13 is directly opposite any one of the four corners of the outer region 22.

[0036] In this embodiment, the opening angle of the V-shaped opening pattern 13 is 90°.

[0037] Preferably, the grid-type opening pattern 11 includes a plurality of arrayed square-shaped opening pattern units.

[0038] Furthermore, the width dimension of the U-shaped opening graphic unit along the Y direction is smaller than the width dimension of the I-shaped opening graphic along the Y direction.

[0039] In this embodiment, the width of the I-shaped opening pattern 12 along the Y direction is twice the width of the U-shaped opening pattern unit along the Y direction.

[0040] Preferably, the ratio of the thickness of the photoresist layer to the maximum critical dimension of the island-shaped photoresist unit 31 covering the inner region 21 is greater than 10:1; the ratio of the thickness of the photoresist layer to the maximum critical dimension of the V-shaped photoresist unit 32 covering the outer region 22 is less than 10:1; and the ratio of the thickness of the photoresist layer to the maximum critical dimension of the elongated photoresist unit 33 covering the outer region 22 is less than 10:1.

[0041] Specifically, any photoresist layer covering the internal region 21 is an island-shaped photoresist unit 31. In this embodiment, referencing... Figure 3Any photoresist layer covering the internal region 21 is rectangular. That is, the aspect ratio of any island-shaped photoresist unit 31 covering the internal region 21 is greater than 10:1.

[0042] Furthermore, the photoresist layer covering the peripheral region 22 has three structures: the first is a V-shaped photoresist unit 32, the second is a strip-shaped photoresist unit 33, and the third is a square photoresist unit 34 located at the four corners. In this embodiment, the aspect ratio of both the V-shaped photoresist unit 32 and the strip-shaped photoresist unit 33 is less than 10:1.

[0043] Further, step S4 is performed: using the patterned photoresist layer 10 as a mask, an ion implantation process is performed on the pixel region 20 to form an isolation region in the pixel region 20.

[0044] Finally, step S5 is performed: the patterned photoresist layer 10 is removed.

[0045] Based on the same inventive concept, this application also provides a photoresist pattern structure, see reference. Figure 3 The photoresist pattern structure includes: a patterned photoresist layer 10, a grid-shaped opening pattern 11, an I-shaped opening pattern 12, and a V-shaped opening pattern 13. The grid-shaped opening pattern 11, the I-shaped opening pattern 12, and the V-shaped opening pattern 13 are all located in the patterned photoresist layer 10. The grid-shaped opening pattern 11 is located above the inner region 21 of the pixel region 20. The V-shaped opening pattern 13 is located above the four corners of the outer region 22 of the pixel region. The I-shaped opening pattern 12 is located above the outer region 22 of the pixel region 20 and is connected to the end of the grid-shaped opening pattern 11.

[0046] The photoresist pattern structure is a mask for the ion implantation process of the pixel area at the bottom of the photoresist pattern structure. The grid-shaped opening pattern 11, the I-shaped opening pattern 12, and the V-shaped opening pattern 13 are ion implantation windows of the pixel area 20, so as to form an isolation region in the pixel area 20 through ion implantation.

[0047] Preferably, the opening of any one of the V-shaped opening patterns 13 is directly opposite any one of the four corners of the outer region 22.

[0048] In this embodiment, the opening angle of the V-shaped opening pattern 13 is 90°.

[0049] Preferably, the grid-type opening pattern 11 includes a plurality of arrayed square-shaped opening pattern units.

[0050] Furthermore, the width dimension of the U-shaped opening graphic unit along the Y direction is smaller than the width dimension of the I-shaped opening graphic along the Y direction.

[0051] In this embodiment, the width of the I-shaped opening pattern 12 along the Y direction is twice the width of the U-shaped opening pattern unit along the Y direction.

[0052] In this application, an ion implantation process is performed on the pixel area using a patterned photoresist layer as a mask to form an isolation region within the pixel area. The patterned photoresist layer includes a grid-shaped opening pattern, multiple I-shaped opening patterns, and four V-shaped opening patterns. The grid-shaped opening patterns are located above the inner region, the V-shaped opening patterns are located above the four corners of the outer region, and the I-shaped opening patterns are located above the outer region and connected to the ends of the grid-shaped opening patterns. By optimizing the outermost pattern design of the photoresist layer, this application increases the area of ​​each piece of photoresist in the outer region of the pixel area. This allows the photoresist layer at the pixel boundary to receive a certain buffer during the photolithography and development process, preventing the outermost edge of the patterned photoresist layer from collapsing, detaching, or peeling off. This solves the problem of peeling and detachment that easily occurs during exposure of high aspect ratio grid-shaped photoresist, ensuring the stability of ion implantation in the isolation region and thus improving the pixel performance and quality of the image sensor.

[0053] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for improving adhesive delamination around the pixel area of ​​a CIS (CMOS Image Sensor), characterized in that, include: A substrate is provided, the substrate comprising at least a pixel region, the pixel region comprising: a peripheral region and an internal region surrounded by the peripheral region; A photoresist layer is coated on the substrate; The pattern on the photomask is transferred onto the photoresist layer using a photolithography process to form a patterned photoresist layer above the pixel area. The patterned photoresist layer includes a grid-shaped opening pattern, multiple I-shaped opening patterns, and four V-shaped opening patterns. The grid-shaped opening pattern is located above the inner region, the V-shaped opening patterns are located above the four corners of the outer region, and the I-shaped opening patterns are located above the outer region and connected to the ends of the grid-shaped opening pattern. Using the patterned photoresist layer as a mask, an ion implantation process is performed on the pixel region to form an isolation region in the pixel region; Remove the patterned photoresist layer.

2. The method for improving the periphery of the pixel area of ​​CIS according to claim 1, characterized in that, The opening angle of the V-shaped opening pattern is 90°.

3. The method for improving the periphery of the pixel area of ​​CIS according to claim 1, characterized in that, The opening of any one of the V-shaped opening patterns is directly opposite any one of the four corners of the outer region.

4. The method for improving the periphery of the pixel area of ​​CIS according to claim 1, characterized in that, The grid-type opening pattern includes several arrayed square-shaped opening pattern units.

5. The method for improving the periphery of the pixel area of ​​CIS according to claim 4, characterized in that, The width dimension of the U-shaped opening graphic unit along the Y direction is smaller than the width dimension of the I-shaped opening graphic along the Y direction.

6. The method for improving the periphery of the pixel area of ​​CIS according to claim 4, characterized in that, The width of the I-shaped opening pattern along the Y direction is twice the width of the U-shaped opening pattern unit along the Y direction.

7. The method for improving the periphery of the pixel area of ​​CIS according to claim 1, characterized in that, The ratio of the thickness of the photoresist layer to the maximum critical dimension of the photoresist unit of the island-shaped structure covering the inner region is greater than 10:1; the ratio of the thickness of the photoresist layer to the maximum critical dimension of the V-shaped structure photoresist unit covering the outer region is less than 10:1; and the ratio of the thickness of the photoresist layer to the maximum critical dimension of the strip-shaped photoresist unit covering the outer region is less than 10:

1.

8. A photoresist pattern structure, characterized in that, include: The image contains a photoresist layer, a grid-shaped opening pattern, an I-shaped opening pattern, and a V-shaped opening pattern, wherein the grid-shaped opening pattern, the I-shaped opening pattern, and the V-shaped opening pattern are all located in the photoresist layer, the grid-shaped opening pattern is located above the inner region of the pixel area, the V-shaped opening pattern is located above the four corners of the outer region of the pixel area, and the I-shaped opening pattern is located above the outer region of the pixel area and is connected to the end of the grid-shaped opening pattern. The photoresist pattern structure serves as a mask for the ion implantation process of the pixel area at the bottom of the photoresist pattern structure. The grid-shaped opening pattern, the I-shaped opening pattern, and the V-shaped opening pattern serve as ion implantation windows for the pixel area, thereby forming an isolation region in the pixel area through ion implantation.

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