Photomask and method for manufacturing the same

Abstract

The application discloses a photomask and a manufacturing method thereof. The photomask comprises a transparent substrate, the transparent substrate comprises a first surface and a second surface opposite to the first surface; a plurality of discrete shielding patterns are arranged on the first surface of the transparent substrate; when the interval between two adjacent shielding patterns is abnormal, the first surface of the transparent substrate between the two adjacent shielding patterns with abnormal interval further comprises a linear Fresnel lens structure, the linear Fresnel lens structure is used for converging or diverging the exposure light rays into normal size after the exposure light rays are incident through the second surface of the transparent substrate and pass through the first surface of the transparent substrate between the two adjacent shielding patterns with abnormal interval. The application can repair the large interval or small interval between two shielding patterns.

Description

Technical Field

[0001] This application relates to the field of photomasks, and more particularly to a photomask capable of repairing abnormal sizes or abnormal spacing and a method for manufacturing the same. Background Technology

[0002] Photolithography is an indispensable and crucial technology in integrated circuit manufacturing. The photolithography process typically includes the following steps: first, a photoresist or other photosensitive material is coated onto the wafer surface; after the photoresist material dries, a mask pattern on a photomask is exposed onto the photoresist photosensitive material using a specific light source through an exposure machine; subsequently, the photoresist photosensitive material is developed with a developer, forming a photoresist pattern on the wafer surface. This photoresist pattern serves as a mask pattern in subsequent ion implantation or etching processes.

[0003] Existing photomasks generally include: a transparent substrate; a plurality of discrete masking patterns (or masking patterns) formed on the surface of the transparent substrate; an annular frame on the surface of the transparent substrate, the annular frame surrounding the masking patterns; and a protective film on the top surface of the annular frame, the protective film and the annular frame being used to seal the photomask.

[0004] However, defects can easily be introduced into the photomask during the photomask fabrication process. These defects cause errors in the pattern of the photomask, such as miss size defects, which are specifically the gap between two adjacent masking patterns that is too large or too small. Therefore, it is necessary to repair the defects on the photomask to reduce the pattern error in the photomask and obtain a photomask that meets the design requirements. Summary of the Invention

[0005] Some embodiments of this application provide a method for fabricating a photomask, including:

[0006] A transparent substrate is provided, the transparent substrate including a first surface and a second surface opposite to the first surface;

[0007] Several discrete masking patterns are formed on the first surface of the transparent substrate;

[0008] When there is an abnormality in the spacing between two adjacent masking patterns, a linear Fresnel lens structure is formed on the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing. The linear Fresnel lens structure is used to converge or diverge the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing.

[0009] In some embodiments, the anomaly includes a spacing between two adjacent occlusion patterns that is greater than a standard value, or a spacing between two adjacent occlusion patterns that is less than a standard value.

[0010] In some embodiments, when the spacing between two adjacent masking patterns is greater than a standard value, the surface of the formed linear Fresnel lens structure is a plurality of convex lens structures that are centrally symmetrical, and the linear Fresnel lens structure is used to converge the exposure light incident through the second surface of the transparent substrate to a normal size after passing through the first surface of the transparent substrate between two adjacent masking patterns with abnormal spacing.

[0011] In some embodiments, when the spacing between two adjacent masking patterns is greater than a standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

[0012] In some embodiments, when the spacing between two adjacent masking patterns is less than a standard value, the surface of the formed linear Fresnel lens structure is a plurality of concave lens structures that are centrally symmetrical, and the linear Fresnel lens structure is used to diffuse the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between two adjacent masking patterns with abnormal spacing.

[0013] In some embodiments, when the spacing between two adjacent masking patterns is less than a standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

[0014] In some embodiments, the linear Fresnel lens structure is formed by directly processing the first surface of a transparent substrate between two adjacent shielding patterns with an abnormal spacing.

[0015] In some embodiments, the linear Fresnel lens structure is formed by processing the first surface of the transparent substrate using a femtosecond laser etching process or an electron beam etching process.

[0016] Some embodiments of this application also provide a photomask, including:

[0017] A transparent substrate, the transparent substrate including a first surface and a second surface opposite to the first surface;

[0018] A plurality of discrete masking patterns located on the first surface of the transparent substrate;

[0019] When there is an abnormality in the spacing between two adjacent masking patterns, the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing also has a linear Fresnel lens structure. The linear Fresnel lens structure is used to converge or diverge the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing.

[0020] In some embodiments, the anomaly includes a spacing between two adjacent occlusion patterns that is greater than a standard value, or a spacing between two adjacent occlusion patterns that is less than a standard value.

[0021] In some embodiments, when the spacing between two adjacent masking patterns is greater than a standard value, the surface of the linear Fresnel lens structure is a plurality of convex lens structures that are centrally symmetrical, and the linear Fresnel lens structure is used to converge the exposure light incident through the second surface of the transparent substrate to a normal size after passing through the first surface of the transparent substrate between two adjacent masking patterns with abnormal spacing.

[0022] In some embodiments, when the spacing between two adjacent masking patterns is greater than a standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

[0023] In some embodiments, when the spacing between two adjacent masking patterns is less than a standard value, the surface of the linear Fresnel lens structure is a plurality of concave lens structures that are centrally symmetrical, and the linear Fresnel lens structure is used to diffuse the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between two adjacent masking patterns with abnormal spacing.

[0024] In some embodiments, when the spacing between two adjacent masking patterns is less than a standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

[0025] In some embodiments, it further includes: an annular frame surrounding the shielding pattern located on an edge region of a first surface of the transparent substrate; and a protective film located on the top surface of the annular frame to enclose the space within the annular frame.

[0026] The photomask in some of the foregoing embodiments of this application includes: a transparent substrate, the transparent substrate including a first surface and a second surface opposite to the first surface; a plurality of discrete masking patterns located on the first surface of the transparent substrate; when there is an abnormality in the spacing between two adjacent masking patterns, the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing also has a linear Fresnel lens structure, the linear Fresnel lens structure being used to converge or diverge the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing. When there is an abnormality in the spacing between two adjacent masking patterns, because the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing has a linear Fresnel lens structure, the exposure light incident through the second surface of the transparent substrate is converged or diverged into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing through the linear Fresnel lens structure, thereby correcting the excessively large or small spacing between the two masking patterns. Attached Figure Description

[0027] Figures 1-15 This is a schematic diagram of the photomask fabrication process in some embodiments of this application. Detailed Implementation

[0028] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. In describing the embodiments of this application in detail, for ease of explanation, the schematic diagrams may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of this application. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0029] This application first provides a method for fabricating a photomask, and the photomask fabrication process will be described in detail below with reference to the accompanying drawings.

[0030] refer to Figure 1 A transparent substrate 201 is provided, the transparent substrate 201 including a first surface 11 and a second surface 12 opposite to the first surface 11.

[0031] The transparent substrate 201 serves as the carrier of the photomask. The transparent substrate 201 is made of a light-transmitting material with a light transmittance greater than 90%. In some embodiments, the transparent substrate 201 can be made of quartz glass or soda glass. In other embodiments, the transparent substrate 201 can also be made of fused silica, calcium fluoride, silicon nitride, titanium dioxide alloy, or sapphire.

[0032] In some embodiments, the transparent substrate 201 may include a central region and an edge region surrounding the central region. The central region may be square, circular, or other suitable shapes, and the edge region may be annular, surrounding the central region. The central region may subsequently be used to form a masking pattern (or a masking pattern), and the central region may also be used to form a phase-shifting layer. The edge region may subsequently be used to form an annular frame.

[0033] refer to Figure 2 A masking pattern material layer 207 is formed on the first surface 21 of the transparent substrate 201. The masking pattern material layer 207 is subsequently used to form a masking pattern.

[0034] The material of the masking pattern material layer 207 is an opaque material. The masking pattern material layer 207 can be a single-layer or multi-layer stacked structure (e.g., a stacked structure of two or more layers), and the subsequently formed masking pattern is also a single-layer or multi-layer stacked structure (e.g., a stacked structure of two or more layers). In some embodiments, the material of the masking pattern material layer 207 can be one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, or tantalum. In other embodiments, the material of the masking pattern material layer 207 can also be one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, tantalum, chromium oxide, iron oxide, niobium oxide, chromium nitride, molybdenum trioxide, molybdenum nitride, chromium oxide, titanium nitride, zirconium nitride, titanium oxide, tantalum nitride, tantalum oxide, silicon dioxide, niobium nitride, silicon nitride, neutral alumina, and alumina.

[0035] In some embodiments, the masking pattern material layer 207 is formed by a sputtering process, an electroplating process, or a vapor deposition process.

[0036] In some embodiments, before forming the masking pattern material layer 207, a phase-shifting layer (not shown) may be formed on the surface of the intermediate region 21 of the transparent substrate 201. The phase-shifting layer is used to change the phase of the exposure light incident on the substrate to improve the resolution during exposure. The material of the phase-shifting layer is MoSi or MoSiON.

[0037] refer to Figure 3 Etching the masking pattern material layer 207 (reference) Figure 2 A plurality of discrete masking patterns 202 are formed on the first surface 11 of the transparent substrate 201.

[0038] The etching of the masking pattern material layer 207 can be performed using anisotropic dry etching or other suitable etching processes.

[0039] The formed plurality of occlusion patterns 202 are mutually independent, and the occlusion pattern 202 can be a rectangle, a square, a composite pattern composed of multiple rectangles, a composite pattern composed of multiple squares, or a composite pattern composed of multiple rectangles and squares.

[0040] During the fabrication of photomasks, the process is mostly normal, but abnormalities can sometimes occur. Therefore, it is necessary to monitor the photomask fabrication process. Measuring the distance between two adjacent masking patterns 202 is one relatively effective monitoring method. The distance between adjacent masking patterns is generally the straight-line distance between the two opposite sides of two adjacent masking patterns 202, for example... Figure 3 The spacing between adjacent occlusion patterns 202a and 202b is denoted by D1.

[0041] Because the manufacturing process can have both normal and abnormal states, the spacing between adjacent masking patterns may be normal or abnormal. Normal spacing between adjacent masking patterns means that the spacing between adjacent masking patterns is equal to the standard value. Abnormal spacing between adjacent masking patterns means that the spacing between adjacent masking patterns is greater than or less than the standard value. The standard value is a specific numerical value A, such as 100nm. The standard value can also be a range value A±B%, such as 100nm±10%.

[0042] When the spacing between adjacent masking patterns 202 is abnormal, using such an abnormal photomask for semiconductor chip fabrication will also result in abnormal spacing between the photolithographic patterns formed on the wafer, easily leading to wafer scrap. Therefore, when the spacing between adjacent masking patterns 202 is abnormal, the photomask needs to be reworked or repaired. Repair processing is widely used due to its low cost and minimal damage to the photomask. Specifically, in this embodiment, referring to... Figure 4If the spacing D1 between adjacent masking patterns 202a and 202b is too large (spacing D1 is greater than the standard value), when the exposure light 21 is incident from the second surface 12 of the transparent substrate 201, part of the exposure light is blocked by the masking pattern after passing through the transparent substrate 201, and another part of the exposure light 22 passes through the transparent substrate 201 and is emitted from the first surface 11 of the transparent substrate 201 between the masking patterns 202, reaching the target position 23 (the target position 23 is a specific position below the photomask or the incident end of the optical system of the exposure equipment. The exposure light 22 transmitted between the masking patterns 202 needs to be transmitted through the optical system to reach the photoresist layer on the wafer surface to expose the photoresist layer). Since the spacing D1 between adjacent masking patterns 202a and 202b is too large, the size D2 of the exposure light 22 transmitted through the first surface 11 of the transparent substrate 201 between the adjacent masking patterns 202a and 202b at the target position 23 will also be too large.

[0043] In other embodiments, reference is made to Figure 9 and Figure 10 The spacing D1 between adjacent masking patterns 202a and 202b may also be too small (spacing D1 is less than the standard value), so the size D2 of the exposure light 22 passing through the first surface 11 of the transparent substrate 201 between adjacent masking patterns 202a and 202b at the target position 23 will also be too small.

[0044] refer to Figure 5 and Figure 6 Or refer to Figure 11 and Figure 12 , Figure 6 for Figure 5 A top view of the middle section of the structure. Figure 12 for Figure 11 The enlarged schematic diagram of the linear Fresnel lens structure shows that when there is an abnormality in the spacing D1 between two adjacent shielding patterns (202a, 202b), a linear Fresnel lens structure 205 is formed on the first surface 11 of the transparent substrate 201 between the two adjacent shielding patterns (202a, 202b) with abnormal spacing D1. The linear Fresnel lens structure 205 is used to converge or diverge the exposure light incident through the second surface 12 of the transparent substrate 201 into a normal size after passing through the first surface 11 of the transparent substrate 201 between the two adjacent shielding patterns (202a, 202b) with abnormal spacing.

[0045] When using the photomask of this application for exposure or photolithography, the exposure light enters from the second surface 12 of the transparent substrate 201 and exits from the first surface 11 of the transparent substrate 201 between adjacent masking patterns 202.

[0046] The anomaly includes a spacing D1 between two adjacent occlusion patterns (202a, 202b) that is greater than a standard value, or a spacing D1 between two adjacent occlusion patterns (202a, 202b) that is less than a standard value. In one embodiment, reference... Figure 5 , Figure 6 and Figure 8 When the distance D1 between two adjacent masking patterns (202a, 202b) is greater than the standard value (distance D1 is too large), the surface of the formed linear Fresnel lens structure 205 is a plurality of convex lens structures that are symmetrical about the central axis. The linear Fresnel lens structure 205 is used to converge the exposure light incident through the second surface 12 of the transparent substrate 201 to the normal size D2 after passing through the first surface 11 of the transparent substrate 201 between the two adjacent masking patterns (202a, 202b) with abnormal spacing. This allows the excessive distance D1 between the two masking patterns (202a, 202b) to be corrected.

[0047] In one specific embodiment, reference is made to Figure 6 The linear Fresnel lens structure 205 has a series of serrated grooves 21 on its surface, and the surfaces between adjacent grooves 21 are upwardly convex, forming multiple convex lens structures 22. The multiple convex lens structures 22 are symmetrical about a central axis 24. In some embodiments, the width of the middle convex lens structure 22 in the linear Fresnel lens structure 205 is greater than the width of the two convex lens structures 22 on both sides, and the angles of the multiple grooves 21 can be different in the direction from the central axis 24 to both sides.

[0048] In some embodiments, reference Figure 7 When the distance D1 between two adjacent occlusion patterns (202a, 202b) is greater than a standard value, and the distance D1 gradually decreases or increases along the two occlusion patterns (202a, 202b), the linear Fresnel lens structure 205 also gradually decreases or increases along the two occlusion patterns (202a, 202b) accordingly, so that the repair of the distance between the two occlusion patterns (202a, 202b) is more accurate. Specifically, Figure 7 In the process, the distance D1 between the two masking patterns (202a, 202b) gradually increases along the extension direction Y of the two masking patterns (202a, 202b), and the linear Fresnel lens structure 205 also gradually increases along the extension direction Y of the two masking patterns (202a, 202b).

[0049] In some embodiments, when the spacing between two adjacent masking patterns is less than a standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

[0050] In one embodiment, reference Figure 11 , Figure 12 and Figure 13 When the distance D1 between two adjacent masking patterns (202a, 202b) is less than the standard value (distance D1 is too small), the surface of the formed linear Fresnel lens structure 205 is a plurality of concave lens structures that are symmetrical about the central axis. The linear Fresnel lens structure 205 is used to diverge the exposure light incident through the second surface 12 of the transparent substrate 201 into a normal size D2 after passing through the first surface 11 of the transparent substrate 201 between the two adjacent masking patterns (202a, 202b) with abnormal spacing, thereby correcting the small distance D1 between the two masking patterns (202a, 202b).

[0051] In one specific embodiment, reference is made to Figure 12 The linear Fresnel lens structure 205 has a series of serrated grooves 25 on its surface, with the surfaces between adjacent grooves 25 being concave downwards, forming multiple concave lens structures 26. These multiple concave lens structures 26 are symmetrical about a central axis 24. In some embodiments, the width of the middle concave lens structure 26 in the linear Fresnel lens structure 205 is greater than the width of the concave lens structures 26 on either side. The angles of the multiple grooves 25 can be different in the direction from the central axis 24 to both sides.

[0052] In some embodiments, reference Figure 5 or Figure 11 The linear Fresnel lens structure 205 is formed by directly processing the first surface 11 of the transparent substrate 201 between two adjacent shielding patterns (202a, 202b) with abnormal spacing, making the formation process simple and convenient. Furthermore, the formed linear Fresnel lens structure 205 effectively converges or diverges the exposure light incident through the second surface 12 of the transparent substrate 201 into a normal size after passing through the first surface 11 of the transparent substrate 201 between the two adjacent shielding patterns (202a, 202b) with abnormal spacing.

[0053] In one specific embodiment, the linear Fresnel lens structure 205 is formed by processing the first surface 11 of the transparent substrate 201 through a femtosecond laser etching process or an electron beam etching process. The formed linear Fresnel lens structure 205 has a good structure and does not affect the transmittance of the exposed light or has a small impact.

[0054] In some embodiments, reference Figure 14 or Figure 15 In some embodiments, reference is made to Figure 4 It also includes: forming an annular frame 204 surrounding the shielding pattern 202 on the edge region surface of the first surface 11 of the transparent substrate 201; and forming a protective film 206 on the top surface of the annular frame 204 to close the space inside the annular frame 204.

[0055] The annular frame 204 is used to support the protective film that is subsequently formed. The annular frame 204 and the protective film that are subsequently formed can isolate the masking pattern 202 on the photomask 201 and the surface of the middle area of ​​the photomask 201 from the external environment, preventing pollution from the external environment.

[0056] The annular frame 204 is a hollow ring, and the material of the annular frame 204 is a material with a certain mechanical strength. In some embodiments, the material of the annular frame 204 is aluminum. In other embodiments, the material of the annular frame 204 can be aluminum alloy, ceramic, carbon steel, or other suitable metallic or non-metallic materials.

[0057] In some embodiments, the annular frame 204 is adhered to the edge region of the transparent substrate by an adhesive layer 203.

[0058] The material of the adhesion layer 203 is an organic adhesive. In some embodiments, the organic adhesive is a rubber adhesive, a polyurethane adhesive, an acrylic adhesive, a SEBS (styrene-vinyl butene-styrene) adhesive, a SEPS (styrene-vinyl propylene-styrene) adhesive, or a siloxane adhesive.

[0059] The protective film 206 is made of a light-transmitting material.

[0060] Some embodiments of this application also provide a photomask, see reference. Figure 5 and Figure 6 Or refer to Figure 11 and Figure 12 ,include:

[0061] A transparent substrate 201, the transparent substrate 201 including a first surface 11 and a second surface 12 opposite to the first surface 11;

[0062] A plurality of discrete masking patterns 202 located on the first surface 11 of the transparent substrate 201;

[0063] When there is an abnormality in the spacing D1 between two adjacent masking patterns (202a, 202b), the first surface 11 of the transparent substrate 201 between the two adjacent masking patterns (202a, 202b) with abnormal spacing D1 also has a linear Fresnel lens structure 205. The linear Fresnel lens structure 205 is used to converge or diverge the exposure light incident through the second surface 12 of the transparent substrate 201 into a normal size after passing through the first surface 11 of the transparent substrate 201 between the two adjacent masking patterns (202a, 202b) with abnormal spacing.

[0064] In some embodiments, the anomaly includes a spacing between two adjacent occlusion patterns that is greater than a standard value, or a spacing between two adjacent occlusion patterns that is less than a standard value.

[0065] In some embodiments, reference Figure 5 , Figure 6 and Figure 8 When the distance D1 between two adjacent masking patterns (202a, 202b) is greater than the standard value, the surface of the linear Fresnel lens structure 205 is a plurality of convex lens structures that are centrally symmetrical. The linear Fresnel lens structure 205 is used to converge the exposure light incident through the second surface 12 of the transparent substrate 201 to a normal size D2 (reference value) after passing through the first surface 11 of the transparent substrate 201 between two adjacent masking patterns (202a, 202b) with abnormal spacing. Figure 8 ).

[0066] In some embodiments, reference Figure 7 When the spacing between two adjacent occlusion patterns (202a, 202b) is greater than the standard value, and the spacing D1 gradually decreases or increases along the two occlusion patterns (202a, 202b), the linear Fresnel lens structure 205 also gradually decreases or increases along the two occlusion patterns (202a, 202b).

[0067] In some embodiments, reference Figures 11-13 When the distance D1 between two adjacent masking patterns (202a, 202b) is less than a standard value, the surface of the linear Fresnel lens structure 205 is a plurality of concave lens structures that are centrally symmetrical. The linear Fresnel lens structure 205 is used to diverge the exposure light incident through the second surface 12 of the transparent substrate 201 into a normal size D2 (reference value) after passing through the first surface 11 of the transparent substrate 201 between two adjacent masking patterns (202a, 202b) with abnormal spacing. Figure 13 ).

[0068] In some embodiments, when the spacing between two adjacent masking patterns is less than a standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

[0069] In some embodiments, reference Figure 14 or Figure 15 It also includes: an annular frame 204 surrounding the shielding pattern 202 on the edge region of the first surface 11 of the transparent substrate 201; and a protective film 206 on the top surface of the annular frame 204 that closes the space inside the annular frame.

[0070] It should be noted that the limitations or descriptions of the same or similar parts in some embodiments of the photomask of this application and some embodiments of the aforementioned photomask formation method will not be repeated here. For details, please refer to the limitations or descriptions of the corresponding parts in some embodiments of the aforementioned photomask formation method.

[0071] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.

Claims

1. A method for fabricating a photomask, characterized in that, include: A transparent substrate is provided, the transparent substrate including a first surface and a second surface opposite to the first surface; Several discrete masking patterns are formed on the first surface of the transparent substrate; When there is an abnormality in the spacing between two adjacent masking patterns, a linear Fresnel lens structure is formed on the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing. The linear Fresnel lens structure is used to converge or diverge the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing. The linear Fresnel lens structure is formed by directly processing the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing. No linear Fresnel lens structure is formed on the first surface of the transparent substrate between two adjacent masking patterns with normal spacing.

2. The method for fabricating a photomask as described in claim 1, characterized in that, The anomaly includes a spacing between two adjacent occlusion patterns that is greater than the standard value, or a spacing between two adjacent occlusion patterns that is less than the standard value.

3. The method for fabricating a photomask as described in claim 2, characterized in that, When the spacing between two adjacent masking patterns is greater than the standard value, the surface of the formed linear Fresnel lens structure is a plurality of convex lens structures that are symmetrical about the central axis. The linear Fresnel lens structure is used to converge the exposure light incident through the second surface of the transparent substrate to the normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing.

4. The method for fabricating a photomask as described in claim 3, characterized in that, When the spacing between two adjacent masking patterns is greater than the standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

5. The method for fabricating a photomask as described in claim 2, characterized in that, When the spacing between two adjacent masking patterns is less than the standard value, the surface of the formed linear Fresnel lens structure is a plurality of concave lens structures that are symmetrical about the central axis. The linear Fresnel lens structure is used to diverge the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing.

6. The method for fabricating a photomask as described in claim 5, characterized in that, When the spacing between two adjacent masking patterns is less than the standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

7. The method for fabricating a photomask as described in claim 1, characterized in that, The linear Fresnel lens structure is formed by processing the first surface of the transparent substrate using femtosecond laser etching or electron beam etching.

8. A photomask, characterized in that, include: A transparent substrate, the transparent substrate including a first surface and a second surface opposite to the first surface; A plurality of discrete masking patterns located on the first surface of the transparent substrate; When there is an abnormality in the spacing between two adjacent masking patterns, the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing also has a linear Fresnel lens structure. The linear Fresnel lens structure is used to converge or diverge the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing. The linear Fresnel lens structure is formed by directly processing the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing. No linear Fresnel lens structure is formed on the first surface of the transparent substrate between two adjacent masking patterns with normal spacing.

9. The photomask as described in claim 8, characterized in that, The anomaly includes a spacing between two adjacent occlusion patterns that is greater than the standard value, or a spacing between two adjacent occlusion patterns that is less than the standard value.

10. The photomask as described in claim 9, characterized in that, When the spacing between two adjacent masking patterns is greater than the standard value, the surface of the linear Fresnel lens structure is a plurality of convex lens structures that are symmetrical about the central axis. The linear Fresnel lens structure is used to converge the exposure light incident through the second surface of the transparent substrate to the normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing.

11. The photomask as described in claim 10, characterized in that, When the spacing between two adjacent masking patterns is greater than the standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

12. The photomask as described in claim 11, characterized in that, When the spacing between two adjacent masking patterns is less than the standard value, the surface of the linear Fresnel lens structure is a plurality of concave lens structures that are symmetrical about the central axis, and the linear Fresnel lens structure is used to diverge the exposure light incident through the second surface of the transparent substrate into a normal size after passing through the first surface of the transparent substrate between the two adjacent masking patterns with abnormal spacing.

13. The photomask as described in claim 12, characterized in that, When the spacing between two adjacent masking patterns is less than the standard value, and the spacing gradually decreases or increases along the two masking patterns, the linear Fresnel lens structure also gradually decreases or increases along the two masking patterns accordingly.

14. The photomask as described in claim 9, characterized in that, Also includes: An annular frame surrounding the masking pattern located on the edge region of the first surface of the transparent substrate; A protective membrane located on the top surface of the annular frame to enclose the space inside the annular frame.

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