A photolithography mask and a method of forming the same

Abstract

The application provides a photolithography mask and a forming method thereof. The photolithography mask comprises a transparent substrate, the transparent substrate comprises an outer ring cutting path area, the outer ring cutting path area comprises an opaque area and a light transmission area, and the light transmission area is symmetrical about a horizontal or vertical middle axis of the transparent substrate; a first opaque layer is located on the transparent substrate surface of the opaque area; and a second opaque layer is located on part of the transparent substrate surface of the light transmission area. The application provides a photolithography mask and a forming method thereof. The second opaque layer is formed in the light transmission area of the outer ring cutting path area, and even if twice exposure is performed, overexposure does not occur, the chip close to the outer ring cutting path area is prevented from being etched, and damage to the chip is avoided.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a photomask and a method for forming the same. Background Technology

[0002] Photolithography is a key process in semiconductor manufacturing. The photolithography process mainly includes: applying photoresist, exposure, and development. During exposure, a photomask is required.

[0003] Current photolithography masks still have design flaws regarding the peripheral dicing area. Due to double exposure, areas of the chip near the peripheral dicing area that should be exposed are also exposed, potentially damaging this portion of the chip during subsequent etching.

[0004] Therefore, it is necessary to provide more effective and reliable technical solutions. Summary of the Invention

[0005] This application provides a photomask and a method for forming the same, which can prevent the chip near the peripheral dicing area from being etched and avoid damage to the chip.

[0006] One aspect of this application provides a photomask, comprising: a transparent substrate, the transparent substrate including an outer ring dicing region, the outer ring dicing region including a light-shielding region and a light-transmitting region, the light-transmitting region being symmetrical about a horizontal or vertical central axis of the transparent substrate; a first light-shielding layer located on the surface of the transparent substrate in the light-shielding region; and a second light-shielding layer located on a portion of the surface of the transparent substrate in the light-transmitting region.

[0007] In some embodiments of this application, the patterns of the second light-shielding layer in the light-transmitting areas located at mutually symmetrical positions are complementary in the light-transmitting areas.

[0008] In some embodiments of this application, the second light-shielding layer in the light-transmitting area located at mutually symmetrical positions is symmetrical about the center of the transparent substrate.

[0009] In some embodiments of this application, the second light-shielding layer of the light-transmitting area located in mutually symmetrical positions is located at the outer edge of the outer ring cutting channel area.

[0010] In some embodiments of this application, the area of ​​the second light-shielding layer accounts for more than 0 and less than or equal to 50% of the area of ​​the light-transmitting zone.

[0011] In some embodiments of this application, the area of ​​the second light-shielding layer accounts for 50% of the light-transmitting area.

[0012] Another aspect of this application provides a method for forming a photomask, comprising: providing a transparent substrate, the transparent substrate including an outer ring dicing region, the outer ring dicing region including a light-shielding region and a light-transmitting region, the light-transmitting region being symmetrical about a horizontal or vertical central axis of the transparent substrate; forming a first light-shielding layer and a second light-shielding layer on the surface of the transparent substrate, wherein the first light-shielding layer is located on the transparent substrate surface of the light-shielding region, and the second light-shielding layer is located on a portion of the transparent substrate surface of the light-transmitting region.

[0013] In some embodiments of this application, the patterns of the second light-shielding layer in the light-transmitting areas located at mutually symmetrical positions are complementary in the light-transmitting areas.

[0014] In some embodiments of this application, the second light-shielding layer in the light-transmitting area located at mutually symmetrical positions is symmetrical about the center of the transparent substrate.

[0015] In some embodiments of this application, the second light-shielding layer of the light-transmitting area located in mutually symmetrical positions is located at the outer edge of the outer ring cutting channel area.

[0016] In some embodiments of this application, the area of ​​the second light-shielding layer accounts for more than 0 and less than or equal to 50% of the area of ​​the light-transmitting zone.

[0017] In some embodiments of this application, the area of ​​the second light-shielding layer accounts for 50% of the light-transmitting area.

[0018] In some embodiments of this application, the method for forming the first light-shielding layer and the second light-shielding layer on the surface of the transparent substrate includes sputtering.

[0019] In some embodiments of this application, the method of forming a first light-shielding layer and a second light-shielding layer on the surface of the transparent substrate includes: forming a light-shielding material layer on the surface of the transparent substrate; and etching the light-shielding material layer to form the first light-shielding layer and the second light-shielding layer.

[0020] The photomask and its formation method described in this application form a complementary second light-shielding layer in the light-transmitting area of ​​the peripheral dicing zone. Even with two exposures, there will be no overexposure, which can prevent the chip near the peripheral dicing zone from being etched and avoid damage to the chip. Attached Figure Description

[0021] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale.

[0022] in:

[0023] Figure 1 This is a schematic diagram of a planar structure of a photomask;

[0024] Figure 2 This is a schematic diagram of a partial cross-sectional structure of a photolithography mask.

[0025] Figures 3 to 5 This is a schematic diagram of the steps in a photolithography method for wafers;

[0026] Figure 6 This is a schematic diagram of the planar structure of the photomask described in the embodiments of this application;

[0027] Figure 7 This is a partial cross-sectional structural diagram of the photomask described in an embodiment of this application;

[0028] Figure 8 and Figure 9 This refers to the second light-shielding layer pattern of the photomask described in some embodiments of this application;

[0029] Figures 10 to 12 This is a schematic diagram of each step in the method for photolithography of a wafer as described in the embodiments of this application;

[0030] Figures 13 to 15 This is a schematic diagram of each step in the method for forming a photomask according to an embodiment of this application. Detailed Implementation

[0031] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0032] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0033] Figure 1 This is a schematic diagram of a planar structure of a photomask. Figure 2 This is a schematic diagram of a partial cross-sectional structure of a photomask. Figure 2 For along Figure 1 Cross-sectional view created by the dashed line.

[0034] refer to Figure 1 and Figure 2As shown, a photomask 100 includes: a transparent substrate 101, the transparent substrate 101 including a main region 110 and an outer ring dicing region 120 surrounding the main region 110, the outer ring dicing region 120 including a light-shielding region 122 and a light-transmitting region 121, the light-transmitting region 121 being symmetrical about the horizontal or vertical central axis of the transparent substrate 101 (e.g., Figure 1 The four light-transmitting areas in the light-blocking area 121 are symmetrical vertically and horizontally, respectively; the light-blocking layer 102 is located on the surface of the transparent substrate 101 of the light-blocking area 121.

[0035] When performing the exposure step in the photolithography process using the photomask 100, the position on the chip to be exposed corresponding to the light-transmitting area 121 is exposed. The position on the chip to be exposed corresponding to the light-shielding area 122 is not exposed due to the blocking effect of the light-shielding layer 102.

[0036] Figures 3 to 5 This is a schematic diagram of the steps in a method for photolithography on a wafer.

[0037] refer to Figure 3 As shown, a wafer 200 to be exposed is provided. The wafer 200 includes regions A, B, C, and D separated by dicing channels 210. The area of ​​each region is the same as the area of ​​the main body region 110 of the photomask 100. The width of the dicing channel 210 is the same as the width of the outer dicing channel region 120 of the photomask 100.

[0038] refer to Figure 4 As shown, a photolithography mask 100 is used to expose region A and the dicing channel 210 surrounding region A. Specifically, the position on the wafer 200 corresponding to the light-transmitting region 121 is exposed. The position on the wafer 200 corresponding to the light-shielding region 122 is not exposed due to the shielding effect of the light-shielding layer 102.

[0039] refer to Figure 5 As shown, a photolithographic mask 100 is used to expose region B and the dicing channel 210 surrounding region B. Specifically, the position on the wafer 200 corresponding to the light-transmitting region 121 is exposed. The position on the wafer 200 corresponding to the light-shielding region 122 is not exposed due to the shielding effect of the light-shielding layer 102.

[0040] Similarly, the remaining regions C and D are exposed using photomask 100.

[0041] refer to Figure 5As shown, the cut channel 210 at the boundary between region A and region B is exposed twice, resulting in overexposure. This overexposure causes the chip near the cut channel 210 at the boundary to also be exposed, which will damage this part of the chip during subsequent etching and affect the chip's reliability. Similarly, the above situation will also occur at the boundary between region A and region C, the boundary between region C and region D, and the boundary between region B and region D.

[0042] To address the aforementioned issues, this application provides a photomask and its formation method, which forms a complementary second light-shielding layer in the light-transmitting area of ​​the peripheral dicing zone. Even with two exposures, overexposure will not occur, thus preventing the chip near the peripheral dicing zone from being etched and avoiding damage to the chip.

[0043] Figure 6 This is a schematic diagram of the planar structure of the photomask described in an embodiment of this application. Figure 7 This is a partial cross-sectional structural diagram of the photomask described in an embodiment of this application. Figure 7 For along Figure 6 Cross-sectional view created by the dashed line.

[0044] refer to Figure 6 and Figure 7 As shown, the photolithography mask 300 described in the embodiments of this application includes: a transparent substrate 301, the transparent substrate 301 including a main region 310 and an outer ring dicing region 320 surrounding the main region 310, the outer ring dicing region 320 including a light-shielding region 322 and a light-transmitting region 321, the light-transmitting region 321 being symmetrical about the horizontal or vertical central axis of the transparent substrate 301 (e.g., Figure 6 The four light-transmitting areas are symmetrical both vertically and horizontally.

[0045] In some embodiments of this application, the transparent substrate 301 is made of, for example, quartz glass. The transparent substrate 301 is a transparent material, allowing light of any wavelength to pass through.

[0046] Continue to refer to Figure 6 and Figure 7 As shown, the transparent substrate 301 includes a main region 310 and an outer dicing region 320 surrounding the main region 310. Generally, a wafer includes several chips and dicing lines separating these chips. During the exposure process, because the area of ​​the photomask is much smaller than the area of ​​the entire wafer, it is impossible to expose the entire wafer in one go. Therefore, the entire wafer is generally divided into several regions with a size equivalent to that of the photomask. A photomask is then used to sequentially expose these regions until the entire wafer has been exposed. The main region 310 corresponds to a region on the wafer, which includes several chips and dicing lines. The outer dicing region 320 corresponds to the dicing lines separating the several regions.

[0047] It should be noted that the technical solution of this application is mainly related to the outer ring cutting channel area 320. This application does not impose any restrictions on the structure on the main body area 310. Therefore, in this application, the description of the structure on the main body area 310 is omitted.

[0048] In some embodiments of this application, the structure on the main body region 310 is configured according to actual needs.

[0049] Continue to refer to Figure 6 and Figure 7 As shown, the outer ring cutting channel area 320 includes a light-shielding area 322 and a light-transmitting area 321, and the light-transmitting area 321 is symmetrical about the horizontal or vertical central axis of the transparent substrate 301.

[0050] On a wafer, in addition to the chips that form the main devices, some devices (such as those used for monitoring and detection) are also formed on the dicing ridges during the manufacturing process. Therefore, photolithography is also required on the dicing ridges.

[0051] The outer dicing area 320 mainly includes a light-shielding area 322 and a light-transmitting area 321. The light-shielding area 322 corresponds to the position on the wafer dicing track that does not require exposure. The light-transmitting area 321 corresponds to the position on the wafer dicing track that requires exposure. It should be noted that this application includes... Figure 6 The arrangement of the light-transmitting area 321 and the light-shielding area 322 in the diagram is for illustrative purposes only. In actual processes, the relative positions and number of the light-transmitting and light-shielding areas may vary.

[0052] Continue to refer to Figure 6 and Figure 7 As shown, the photolithography mask 300 further includes a first light-shielding layer 302, which is located on the surface of the transparent substrate 301 of the light-shielding area 322. The light-shielding area 322 corresponds to the position on the wafer dicing track that does not require exposure. That is, the light-shielding area 322 needs to block light. The first light-shielding layer 302 is used to block light.

[0053] In some embodiments of this application, the first light-shielding layer 302 is a material capable of blocking light, such as a metal material, for example, chromium.

[0054] Continue to refer to Figure 6 and Figure 7 As shown, the photolithography mask 300 further includes a second light-shielding layer 303, which is located on the surface of a portion of the transparent substrate 301 in the light-transmitting area 321.

[0055] In some embodiments of this application, the second light-shielding layer 303 is a material capable of blocking light, such as a metal material, for example, chromium.

[0056] In conventional photolithography masks (e.g.) Figure 1 In a traditional double exposure, the light-transmitting area is entirely transparent. Therefore, during two exposures, the exposed area will be overexposed. However, in the technical solution of this application, the light-transmitting area 321 is partially transparent, meaning that some areas of the light-transmitting area 321 are transparent while others are opaque. Thus, even with double exposure, each exposure will only expose a portion of the light-transmitting area, and the combined area of ​​the two exposures will be sufficient to cover the entire light-transmitting area.

[0057] Figure 8 and Figure 9 This is the pattern of the second light-shielding layer of the photomask described in some embodiments of this application.

[0058] In some embodiments of this application, reference is made to Figure 8 As shown, the light-transmitting areas 321 are located in mutually symmetrical positions (e.g. Figure 8 The second light-shielding layer 303 (with two light-transmitting areas symmetrically arranged at the top and bottom) is symmetrical about the center of the transparent substrate 302.

[0059] In some embodiments of this application, reference is made to Figure 9 As shown, the light-transmitting areas 321 are located in mutually symmetrical positions (e.g. Figure 9 The patterns of the second light-shielding layer 303 in the two symmetrical light-transmitting areas are complementary in the light-transmitting areas. The complementarity means that the combined patterns of the second light-shielding layer 303 in the two symmetrical light-transmitting areas equal the shape of the light-transmitting areas.

[0060] It should be noted that, Figure 8 and Figure 9 The pattern of the second light-shielding layer shown is for illustrative purposes only. The pattern of the second light-shielding layer can also be any other shape that meets the requirements.

[0061] In some embodiments of this application, reference is made to Figure 6 As shown, the second light-shielding layer 303, located in a mutually symmetrical position within the light-transmitting area 321, is situated at the outer edge of the outer ring cutting channel area. The area of ​​the second light-shielding layer 303 accounts for 50% of the light-transmitting area, meaning that the patterns of the second light-shielding layer 303 in the mutually symmetrical light-transmitting area 321 are both complementary and centrally symmetrical.

[0062] In some embodiments of this application, reference is made to Figure 8As shown, the area of ​​the second light-shielding layer 303 accounts for more than 0% and less than 50% of the area in the light-transmitting region. In this structure, the position in the light-transmitting region 321 that is exposed twice is close to the center of the light-transmitting region, which will not cause the chip near the outer ring cutting channel area to be exposed.

[0063] Figures 10 to 12 This is a schematic diagram of each step in the method for photolithography of a wafer as described in the embodiments of this application.

[0064] refer to Figure 10 As shown, a wafer 400 to be exposed is provided. The wafer 400 includes regions A, B, C, and D separated by dicing channels 410. The area of ​​each region is the same as the area of ​​the main body region 310 of the photomask 300. The width of the dicing channel 410 is the same as the width of the outer dicing channel region 320 of the photomask 300. Each region includes a plurality of chips and dicing channels (not shown) separating the plurality of chips.

[0065] It should be noted that the wafer region division in this embodiment is merely illustrative. In practice, other suitable divisions can also be used for the wafer region division.

[0066] refer to Figure 11 As shown, a photomask 300 is used to expose region A and the cut path 410 surrounding region A.

[0067] refer to Figure 12 As shown, a photomask 300 is used to expose region B and the cut path 410 surrounding region B.

[0068] Similarly, the remaining regions C and D are exposed using photomask 300.

[0069] refer to Figure 11 and Figure 12 As shown, although the dicing channel 410 at the junction of region A and region B is exposed twice, each exposure only exposes a portion of the light-transmitting area. The combined area of ​​the two exposures equals the area of ​​the light-transmitting area, therefore the wafer position corresponding to the light-transmitting area is not overexposed. Similarly, the junctions of region A and region C, region C and region D, and region B and region D will not be overexposed.

[0070] The photomask described in this application forms a complementary second light-shielding layer in the light-transmitting area of ​​the peripheral dicing zone. Even with two exposures, there will be no overexposure, which can prevent the chip near the peripheral dicing zone from being etched and avoid damage to the chip.

[0071] Figures 13 to 15 This is a schematic diagram of each step in the method for forming a photomask according to an embodiment of this application. Figures 13 to 15 For along Figure 6 Cross-sectional view created by the dashed line.

[0072] refer to Figure 13 As shown, a transparent substrate 501 is provided. The transparent substrate 501 includes a main body region 510 and an outer ring cutting channel region 520 surrounding the main body region 510. The outer ring cutting channel region 520 includes a light-shielding region 522 and a light-transmitting region 521. The light-transmitting region 521 is symmetrical about the horizontal or vertical central axis of the transparent substrate 501.

[0073] In some embodiments of this application, the transparent substrate 501 is made of, for example, quartz glass. The transparent substrate 501 is a transparent material, allowing light of any wavelength to pass through.

[0074] Continue to refer to Figure 13 As shown, the transparent substrate 501 includes a main region 510 and an outer dicing region 520 surrounding the main region 510. Generally, a wafer includes several chips and dicing lines separating these chips. During the exposure process, because the area of ​​the photomask is much smaller than the area of ​​the entire wafer, it is impossible to expose the entire wafer at once. Therefore, the entire wafer is typically divided into several regions with dimensions comparable to the photomask. A photomask is then used to sequentially expose these regions until the entire wafer has been exposed. The main region 510 corresponds to a region on the wafer, which includes several chips and dicing lines. The outer dicing region 520 corresponds to the dicing lines separating the several regions.

[0075] Continue to refer to Figure 13 As shown, the outer ring cutting channel area 520 includes a light-shielding area 522 and a light-transmitting area 521, and the light-transmitting area 521 is symmetrical about the horizontal or vertical central axis of the transparent substrate 501.

[0076] On a wafer, in addition to the chips that form the main devices, some devices (such as those used for monitoring and detection) are also formed on the dicing ridges during the manufacturing process. Therefore, photolithography is also required on the dicing ridges.

[0077] The outer dicing area 520 mainly includes a light-shielding area 522 and a light-transmitting area 521. The light-shielding area 522 corresponds to the position on the wafer dicing track that does not require exposure. The light-transmitting area 521 corresponds to the position on the wafer dicing track that requires exposure.

[0078] refer to Figure 14 and Figure 15As shown, a first light-shielding layer 502 and a second light-shielding layer 503 are formed on the surface of the transparent substrate 501, wherein the first light-shielding layer 502 is located on the surface of the transparent substrate in the light-shielding area, and the second light-shielding layer 503 is located on a portion of the transparent substrate surface in the light-transmitting area.

[0079] In some embodiments of this application, the method of forming a first light-shielding layer 502 and a second light-shielding layer 503 on the surface of the transparent substrate 501 includes: referring to Figure 14 As shown, a light-shielding material layer 504 is formed on the surface of the transparent substrate 501; Reference Figure 15 The light-shielding material layer 504 is etched to form the first light-shielding layer 502 and the second light-shielding layer 503.

[0080] In some embodiments of this application, the method for forming a light-shielding material layer 504 on the surface of the transparent substrate 501 includes sputtering.

[0081] In some embodiments of this application, the first light-shielding layer 502 is a material capable of blocking light, such as a metal material, for example, chromium.

[0082] In some embodiments of this application, the second light-shielding layer 503 is a material capable of blocking light, such as a metal material, for example, chromium.

[0083] In conventional photolithography masks (e.g.) Figure 1 In a traditional double exposure, the light-transmitting area is entirely transparent. Therefore, during two exposures, the exposed area will be overexposed. However, in the technical solution of this application, the light-transmitting area 521 is partially transparent, meaning that some areas of the light-transmitting area 521 are transparent while others are opaque. Thus, even with double exposure, each exposure will only expose a portion of the light-transmitting area, and the combined area of ​​the two exposures will be sufficient to cover the entire light-transmitting area.

[0084] In some embodiments of this application, the second light-shielding layer 503 of the light-transmitting area 521, located in mutually symmetrical positions, is situated at the outer edge of the outer ring cutting channel area. The area of ​​the second light-shielding layer 503 accounts for 50% of the light-transmitting area, meaning that the patterns of the second light-shielding layer 503 in the mutually symmetrical light-transmitting area 521 are both complementary and centrally symmetrical.

[0085] In some embodiments of this application, the area of ​​the second light-shielding layer 503 accounts for more than 0% and less than 50% of the area in the light-transmitting region. In this structure, the location in the light-transmitting region 521 that is exposed twice is close to the center of the light-transmitting region, which will not cause the chip near the outer ring cutting channel area to be exposed.

[0086] This application provides a photomask and a method for forming the same, which forms a complementary second light-shielding layer in the light-transmitting area of ​​the peripheral dicing zone. Even with two exposures, there will be no overexposure, which can prevent the chip near the peripheral dicing zone from being etched and avoid damage to the chip.

[0087] In summary, after reading this application, those skilled in the art will understand that the foregoing application content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.

[0088] It should be understood that the term "and / or" as used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element.

[0089] Similarly, it should be understood that when an element such as a layer, region, or substrate is referred to as being "on" another element, it may be directly on that other element, or there may be intermediate elements present. Conversely, the term "directly" means without intermediate elements. It should also be understood that the terms "comprising," "including," "including," or "comprises," when used in this application, indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0090] It should also be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this application, a first element in some embodiments may be referred to as a second element in other embodiments. The same reference numerals or the same reference signs denote the same elements throughout the specification.

[0091] Furthermore, this application specification describes exemplary embodiments by referring to idealized exemplary cross-sectional views and / or plan views and / or perspective views. Therefore, differences from the illustrated shapes are foreseeable due to factors such as manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but should include deviations in shape caused, for example, by manufacturing processes. For instance, etched areas shown as rectangular typically have circular or curved features. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to illustrate the actual shape of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

Claims

1. A photolithographic mask, characterized in that, include: A transparent substrate, the transparent substrate including an outer ring cutting channel area, the outer ring cutting channel area including a light-shielding area and a light-transmitting area, the light-transmitting area being symmetrical about the horizontal or vertical central axis of the transparent substrate; A first light-shielding layer is located on the surface of a transparent substrate in the light-shielding area; The second light-shielding layer is located on a portion of the transparent substrate surface in the light-transmitting area. The patterns of the second light-shielding layers in the light-transmitting areas located at mutually symmetrical positions are complementary in the light-transmitting areas, and / or the second light-shielding layers in the light-transmitting areas located at mutually symmetrical positions are symmetrical about the center of the transparent substrate.

2. The photolithographic mask as described in claim 1, characterized in that, The second light-shielding layer, located in a mutually symmetrical position within the light-transmitting area, is situated at the outer edge of the outer ring cutting channel area.

3. The photolithographic mask as described in claim 2, characterized in that, The area of ​​the second light-shielding layer accounts for more than 0 and less than or equal to 50% of the area of ​​the light-transmitting zone.

4. The photolithographic mask as described in claim 3, characterized in that, The area of ​​the second light-shielding layer accounts for 50% of the area of ​​the light-transmitting zone.

5. A method for forming a photomask, characterized in that, include: A transparent substrate is provided, the transparent substrate including an outer ring dicing area, the outer ring dicing area including a light-shielding area and a light-transmitting area, the light-transmitting area being symmetrical about the horizontal or vertical central axis of the transparent substrate; A first light-shielding layer and a second light-shielding layer are formed on the surface of the transparent substrate, wherein the first light-shielding layer is located on the surface of the transparent substrate in the light-shielding area, and the second light-shielding layer is located on a portion of the surface of the transparent substrate in the light-transmitting area. The patterns of the second light-shielding layers in the light-transmitting areas located at mutually symmetrical positions are complementary in the light-transmitting areas, and / or the patterns of the second light-shielding layers in the light-transmitting areas located at mutually symmetrical positions are symmetrical about the center of the transparent substrate.

6. The forming method as described in claim 5, characterized in that, The second light-shielding layer, located in a mutually symmetrical position within the light-transmitting area, is situated at the outer edge of the outer ring cutting channel area.

7. The forming method as described in claim 6, characterized in that, The area of ​​the second light-shielding layer accounts for more than 0 and less than or equal to 50% of the area of ​​the light-transmitting zone.

8. The forming method as described in claim 7, characterized in that, The area of ​​the second light-shielding layer accounts for 50% of the area of ​​the light-transmitting zone.

9. The forming method as described in claim 5, characterized in that, Methods for forming a first light-shielding layer and a second light-shielding layer on the surface of the transparent substrate include sputtering.

10. The forming method as described in claim 5, characterized in that, The method for forming a first light-shielding layer and a second light-shielding layer on the surface of the transparent substrate includes: A light-shielding material layer is formed on the surface of the transparent substrate; The light-shielding material layer is etched to form the first light-shielding layer and the second light-shielding layer.

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