Photomask and method for making the same

Abstract

A photomask and a method for forming the same, wherein the method comprises: providing a transparent substrate, the transparent substrate comprising a middle region and an edge region surrounding the middle region; forming a plurality of discrete shielding patterns on the surface of the middle region of the transparent substrate; forming an aerogel layer on the top surface of the shielding patterns; providing an annular frame, adhering the annular frame to the edge region surface of the transparent substrate, the annular frame surrounding the shielding patterns and the aerogel layer; and forming a protective film on the top surface of the annular frame to close the inner space of the annular frame. The method of the present application can prevent the generation of "haze" defects.

Description

Technical Field

[0001] The present application relates to the field of photomasks, and in particular to a photomask capable of preventing the generation of "haze" defects and a method for manufacturing the same. Background Art

[0002] The photolithography process is an indispensable and important technology in the integrated circuit manufacturing process. The photolithography process generally includes the following steps: first, a photosensitive material such as a photoresist is coated on the surface of the wafer. After the photoresist material is dried, the mask pattern on the photomask is exposed to the photoresist photosensitive material with a specific light source by an exposure machine. Subsequently, the photoresist photosensitive material is developed with a developer to form a photoresist pattern on the surface of the wafer. The photoresist pattern is used as a mask pattern in the subsequent ion implantation process or etching process.

[0003] The existing photomask protective film structure generally includes: a transparent substrate; a plurality of discrete shielding patterns (or mask patterns) formed on the surface of the transparent substrate; an annular frame located on the surface of the transparent substrate, the annular frame surrounding the shielding patterns; a protective film located on the top surface of the annular frame, the protective film and the annular frame being used to seal the photomask.

[0004] However, during the use of existing photomasks, foreign body-like growth defects may form on the photomasks. These growth defects are also called "haze", which affects the precision and accuracy of exposure. Summary of the invention

[0005] Some embodiments of the present application provide a method for manufacturing a photomask, including:

[0006] Providing a transparent substrate, the transparent substrate comprising a middle area and an edge area surrounding the middle area;

[0007] forming a plurality of discrete shielding patterns on the surface of the middle region of the transparent substrate;

[0008] forming an aerogel layer on a top surface of the shielding pattern;

[0009] Providing an annular frame, adhering the annular frame to the edge area surface of the transparent substrate, the annular frame surrounding the shielding pattern and the aerogel layer;

[0010] A protective film is formed on the top surface of the annular frame to close the inner space of the annular frame.

[0011] In some embodiments, the size of the top of the aerogel layer is the same as that of the bottom, or the size of the top is smaller than that of the bottom.

[0012] In some embodiments, the top of the aerogel layer is in an upward convex arc shape.

[0013] In some embodiments, the aerogel is a silicon-based aerogel or a carbon-based aerogel.

[0014] In some embodiments, the pore size of the aerogel layer is 1-100 nm, and the density is less than 3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame.

[0015] In some embodiments, the silicon-based aerogel comprises silicon dioxide aerogel.

[0016] In some embodiments, the silica aerogel has a refractive index of <1.01, a transmittance of >=80%, a pore size of 1-50 nm, and a density of <3 kg / m 3 .

[0017] In some embodiments, the formation process of the aerogel layer includes a sol-gel method, a solvent deposition method or a chemical vapor deposition method.

[0018] In some embodiments, the process of forming the aerogel layer using the sol-gel method includes: providing a reaction tank, into which the precursor required by the sol-gel method is introduced; inverting a transparent substrate formed with a shielding layer on top of the reaction tank so that the top surface of the shielding layer is in contact with the precursor; performing a sol-gel reaction process to form an initial aerogel on the top surface of the shielding layer, and applying an electric current to the shielding layer during the sol-gel reaction process; removing the transparent substrate formed with the initial aerogel from the reaction tank, modifying and drying the initial aerogel, and forming an aerogel.

[0019] In some embodiments, the aerogel layer is used to adsorb ammonium ions and sulfate ions as well as contamination particles to prevent "haze" defects from being generated on the surface of the middle area of ​​the photomask and the surface of the shielding pattern.

[0020] In some embodiments, the annular frame is adhered to an edge region of the transparent substrate via an adhesive layer.

[0021] Some embodiments of the present application further provide a photomask, including:

[0022] A transparent substrate, the transparent substrate comprising a middle area and an edge area surrounding the middle area;

[0023] a plurality of discrete shielding patterns located on the surface of the middle region of the transparent substrate;

[0024] an aerogel layer located on the top surface of the shielding pattern

[0025] an annular frame adhered to the surface of the edge region of the transparent substrate, the annular frame surrounding the shielding pattern and the aerogel layer;

[0026] A protective film is located on the top surface of the annular frame to close the inner space of the annular frame.

[0027] In some embodiments, the size of the top of the aerogel layer is the same as that of the bottom, or the size of the top is smaller than that of the bottom.

[0028] In some embodiments, the top of the aerogel layer is in an upward convex arc shape.

[0029] In some embodiments, the aerogel is a silicon-based aerogel or a carbon-based aerogel.

[0030] In some embodiments, the pore size of the aerogel layer is 1-100 nm, and the density is less than 3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame.

[0031] In some embodiments, the silicon-based aerogel comprises silicon dioxide aerogel.

[0032] In some embodiments, the silica aerogel has a refractive index of <1.01, a transmittance of >=80%, a pore size of 1-50 nm, and a density of <3 kg / m 3 .

[0033] In some embodiments, the aerogel layer is used to adsorb ammonium ions and sulfate ions as well as contamination particles to prevent "haze" defects from being generated on the surface of the middle area of ​​the photomask and the surface of the shielding pattern.

[0034] In some embodiments, an adhesive layer is located between the annular frame and a surface of an edge region of the transparent substrate.

[0035] The method for forming a photomask in some of the aforementioned embodiments of the present application provides a transparent substrate, wherein the transparent substrate includes a middle area and an edge area surrounding the middle area; a plurality of discrete shielding patterns are formed on the surface of the middle area of ​​the transparent substrate; an aerogel layer is formed on the top surface of the shielding patterns; an annular frame is provided, the annular frame is adhered to the surface of the edge area of ​​the transparent substrate, the annular frame surrounds the shielding patterns and the aerogel layer; and a protective film that closes the internal space of the annular frame is formed on the top surface of the annular frame. Since the formed aerogel layer is located on the top surface of the shielding pattern, it will not affect or have little effect on the exposure light during the exposure process, and the formed aerogel layer has the characteristics of high porosity and high adsorption, so that the formed aerogel layer can absorb the ammonium ions, sulfate ions and pollution particles (particles) entering from the outside through the pores at the connection of the protective film of the photomask, and can absorb the pollution particles (particles) adsorbed by the protective film (facing the transparent substrate side), the pollution particles (particles) generated by the metal frame due to the environment, and the pollution particles (particles) generated by the embrittlement of the adhesive due to long-term ultraviolet light exposure, and the chemicals (S, N, ammonium ions and sulfur ions, etc.) remaining in the photomask production process can be absorbed by the aerogel, thereby preventing the formation of "haze" defects on the surface of the shielding pattern, the surface of the middle area 21 of the photomask and / or the surface of the phase shift layer during the use of the photomask, thereby improving the precision and accuracy of exposure.

[0036] In one embodiment, the pore size of the aerogel layer is 1-100 nm, and the density is less than 3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame. Under this specific parameter, the aerogel layer can better adsorb ammonium ions, sulfate ions and corresponding pollution particles, while having minimal impact on exposure light. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1-Figure 7 This is a structural schematic diagram of a photomask manufacturing process in some embodiments of the present application;

[0038] Figure 8 Schematic diagram of the formation process of silica aerogel in some embodiments of the present application. DETAILED DESCRIPTION

[0039] During the use of existing photomasks, foreign body-like growth defects may form on the photomasks. These growth defects are also called "haze", which affects the precision and accuracy of exposure.

[0040] Research has found that during the use of photomasks, high-energy photons generated by the exposure light source can cause foreign body-like growth defects to form on the photomask (located on the transparent substrate and / or the surface of the masking pattern). These growth defects are also called "haze" defects.

[0041] Further research found that the material of the "haze" defect includes ammonium sulfate crystals. The "haze" defect is caused by several reasons: 1) During the use of the photomask, ammonium and sulfate ions in the external environment will enter the internal air through the pores at the connection of the protective film, react under the excitation of the high-energy photons generated by the exposure light source, and finally adhere to the photomask to form "haze" (ammonium sulfate crystals). 2) During the use of the photomask, the polluted particles (particles) adsorbed by the protective film (facing the transparent substrate side), the polluted particles (particles) generated by the metal frame due to the environment, and the polluted particles (particles) generated by the adhesive due to long-term ultraviolet light irradiation will enter the air inside the protective film, and finally adhere to the masking pattern or transparent substrate or halftone phase shift film, resulting in adhesion defects. 3) In the existing technology, when making photomasks, a variety of chemicals are used in the process, and some compounds remain in the photomask. These compounds include ammonium ions and sulfur ions. They react under the excitation of high-energy photons generated by the exposure light source to generate "haze" (ammonium sulfate crystals).

[0042] To this end, the present application provides a photomask and a method for manufacturing the same, which can prevent the photomask from generating "haze" defects during use.

[0043] The specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. When describing the embodiments of the present application in detail, for the sake of convenience, the schematic diagrams will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0044] Some embodiments of the present application firstly provide a method for manufacturing a photomask, and the photomask manufacturing process is described in detail below with reference to the accompanying drawings.

[0045] refer to Figure 1 , providing a transparent substrate 201, wherein the transparent substrate 201 includes a middle area 21 and an edge area 22 surrounding the middle area 21; and forming a plurality of discrete shielding patterns 202 on the surface of the middle area 21 of the transparent substrate 201.

[0046] The transparent substrate 201 is used as a carrier of the photomask. The material of the transparent substrate 201 is a light-transmitting material, and the light transmittance of the transparent substrate 201 is greater than 90%. In some embodiments, the material of the transparent substrate 201 can be quartz glass or soda glass. In some other embodiments, the material of the transparent substrate 201 can also be fused silica, calcium fluoride, silicon nitride, titanium oxide alloy, and sapphire.

[0047] The transparent substrate 201 includes a middle area 21 and an edge area 22 surrounding the middle area 21. The middle area 21 may be in a square, circular or other suitable shape, and the edge area 22 is in an annular shape surrounding the middle area 21. The middle area 21 is used to form a shielding pattern (or mask push) 202, and the middle area 21 may also be used to form a phase shift layer, and the edge area 22 is subsequently used to form an annular frame.

[0048] The material of the shielding pattern 202 is an opaque material, and the shielding pattern 202 can be a single-layer or multi-layer stacked structure (such as a stacked structure of two or more layers). In some embodiments, the material of the shielding pattern 202 can be one or more of nickel, aluminum, ruthenium, molybdenum, titanium or tantalum. In some other embodiments, the material of the shielding pattern 202 can also be one or more of 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 aluminum oxide, and aluminum oxide.

[0049] In some embodiments, the formation process of the shielding pattern 202 may include: forming a shielding material layer (not shown in the figure) on the surface of the transparent substrate 201 by a sputtering or deposition process; forming a patterned mask layer (such as a patterned photoresist layer) (not shown in the figure) on the surface of the shielding material layer, wherein the patterned mask layer exposes the area of ​​the shielding material layer that needs to be etched; using the patterned mask layer as a mask, etching away the exposed shielding material layer, and the remaining shielding material layer on the surface of the transparent substrate 201 serves as the shielding pattern 202.

[0050] In other embodiments, before forming the shielding pattern 202, a phase shift layer (not shown in the figure) may be formed on the surface of the middle region 21 of the transparent substrate 201, and the phase shift layer is used to change the phase of the exposure light incident into the substrate to improve the resolution during exposure. The material of the phase shift layer is MoSi or MoSiON.

[0051] refer to Figure 2-Figure 5 , an aerogel layer 205 is formed on the top surface of the shielding pattern 202.

[0052] Since the formed aerogel layer 205 is located on the top surface of the shielding pattern 202, it will not affect or have little effect on the exposure light during the exposure process, and the formed aerogel layer 205 has the characteristics of high porosity and high adsorption, so that the formed aerogel layer 205 can absorb the ammonium ions, sulfate ions and pollution particles (particles) entering from the outside through the pores at the connection of the protective film of the photomask, and can absorb the pollution particles (particles) adsorbed by the protective film (facing the transparent substrate side), the pollution particles (particles) generated by the metal frame due to the environment, and the pollution particles (particles) generated by the embrittlement of the adhesive due to long-term ultraviolet light exposure, and the chemicals (S, N, ammonium ions and sulfur ions, etc.) remaining in the photomask production process can be absorbed by the aerogel, thereby preventing the formation of "haze" defects on the surface of the shielding pattern 202, the surface of the middle area 21 of the photomask 201 and / or the surface of the phase shift layer during the use of the photomask, thereby improving the precision and accuracy of exposure.

[0053] In one embodiment, the aerogel layer 205 has a pore size of 1-100 nm and a density of <3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame. Under this specific parameter, the aerogel layer 205 can better adsorb ammonium ions, sulfate ions and corresponding pollution particles, while having the least impact on the exposure light.

[0054] The size of the top of the aerogel layer 205 is consistent with the size of the bottom, or the size of the top is smaller than the size of the bottom. In this embodiment, the size of the top of the aerogel layer 205 is smaller than the size of the bottom to further reduce the impact on the exposure light. In a specific embodiment, the size of the aerogel layer 205 gradually decreases from the top to the bottom. In another specific embodiment, the top of the aerogel layer 205 is an upward convex arc, which can be a circular arc or an elliptical arc, so that the surface area of ​​the aerogel layer 205 can be increased, thereby enhancing the adsorption performance of the aerogel layer 205. In some other embodiments, the top and / or side wall surface of the aerogel layer 205 can be uneven, which can also increase the surface area of ​​the aerogel layer 205, thereby enhancing the adsorption performance of the aerogel layer 205.

[0055] The aerogel is a silicon-based aerogel or a carbon-based aerogel. In one embodiment, the silicon-based aerogel includes silicon dioxide aerogel.

[0056] In some embodiments, the silica aerogel has a refractive index of <1.01, a transmittance of >=80%, a pore size of 1-50 nm, and a density of <3 kg / m3 When the aerogel layer 205 is made of silica aerogel, its refractive index is small and its light transmittance is high, so that the impact on the exposure light will be smaller, and at the same time, it can ensure a high performance of adsorbing ammonium ions, sulfate ions and corresponding pollution particles.

[0057] The formation process of the aerogel layer 205 includes a sol-gel method, a solvent deposition method or a chemical vapor deposition method.

[0058] The sol-gel method uses compounds containing highly chemically active components as precursors. These raw materials are evenly mixed in the liquid phase, and undergo hydrolysis and condensation chemical reactions to form a stable transparent sol system in the solution. After aging, the sol particles slowly polymerize to form a gel with a three-dimensional spatial network structure. The gel network is filled with solvents that have lost their fluidity. The gel is dried, sintered and solidified to prepare molecular or even nano-substructured or nano-structured aerogels.

[0059] In some embodiments, the process of forming the aerogel layer 205 by the sol-gel method includes: Figure 2 , providing a reaction tank 101, into which a precursor 102 required for a sol-gel method is introduced, for example, when forming an aerogel layer 205 of a silica aerogel material, the precursor 102 includes a silicon source, ethanol and water, and the silicon source includes methyl orthosilicate, ethyl orthosilicate, silica sol or water glass; referring to Figure 3 , the transparent substrate 201 formed with the shielding layer 202 is flipped on the reaction tank 101, so that the top surface of the shielding layer 202 is in contact with the precursor 102; continue to refer to Figure 3 , a sol-gel reaction process is performed to form an initial aerogel 208 on the top surface of the shielding layer 202, such as when an aerogel layer 205 of a silica aerogel material is formed, the initial aerogel 208 is a SiO2 alcohol gel, and a current is applied to the shielding layer during the sol-gel reaction, and the applied current is a weak current (less than 50 mA) to increase the adsorption capacity of the top surface of the shielding layer 202 to the precursor; refer to Figure 4 and Figure 5 The transparent substrate 210 formed with the initial aerogel 208 is removed from the reaction tank 101, and the initial aerogel 208 is modified and dried to form an aerogel 205 (refer to Figure 5 ).

[0060] In some embodiments, reference Figure 8The specific process of forming the aerogel layer 202 of the silica aerogel material by the sol-gel method and using tetraethyl orthosilicate as the silicon source may include: mixing TEOS (tetraethyl orthosilicate), EtOH (ethanol) and H2O (water); adding acid to adjust the pH value, mixing and stirring, and sealing at a constant temperature to form SiO2 alcohol gel; after aging and surface modification, a modified alcohol gel is formed; after solvent replacement and normal pressure drying, SiO2 aerogel is formed.

[0061] In other embodiments, an aerogel material layer covering the surface of the middle area 21 of the shielding layer 202 and the transparent substrate 201 can be directly formed in the annular frame 204, and then the aerogel material layer around the shielding layer 202 is removed, retaining the aerogel material layer on the top surface of the shielding layer 202 as the aerogel layer 205.

[0062] In this embodiment, the top surface of the aerogel layer 205 is lower than the annular frame 204 formed subsequently (refer to Figure 7 In some other embodiments, the top surface of the aerogel layer 205 is flush with the top surface of the annular frame 204 formed subsequently, and the aerogel layer 205 can also be used to support the protective film formed subsequently.

[0063] refer to Figure 6 , provide an annular frame 204, adhere the annular frame 204 to the surface of the edge area 22 of the transparent substrate 201, and the annular frame 204 surrounds the shielding pattern.

[0064] The annular frame 204 is used to support the protective film formed subsequently. The annular frame 204 and the protective film formed subsequently can isolate the shielding pattern 202 on the photomask 201 and the surface of the middle area of ​​the photomask 201 from the external environment to prevent contamination of the external environment.

[0065] The annular frame 202 is in a hollow annular shape, and the material of the annular frame 202 is a material with a certain mechanical strength. In some embodiments, the material of the annular frame 202 is aluminum. In some other embodiments, the material of the annular frame 202 can be aluminum alloy, ceramic, carbon steel or other suitable metal materials or non-metal materials.

[0066] In some embodiments, the annular frame 204 is adhered to the edge region of the transparent substrate through an adhesive layer 203 .

[0067] 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 ethylene butylene styrene) adhesive, a SEPS (styrene ethylene propylene styrene) adhesive or a silicone adhesive.

[0068] Next reference Figure 7 A protective film 206 is formed on the top surface of the annular frame 204 to close the inner space of the annular frame 204 .

[0069] In this embodiment, the top surface of the aerogel layer 205 is flush with the top surface of the annular frame 204, the edge portion of the protective film 206 is located on the top surface of the annular frame 204, and the middle portion of the protective film 206 is located on the top surface of the aerogel layer 205. In other embodiments, when the top surface of the aerogel layer 205 is lower than the top surface of the annular frame 204, the edge portion of the protective film 206 is located on the top surface of the annular frame 204, and the middle portion of the protective film 206 is suspended on the top surface of the aerogel layer 205.

[0070] The material of the protection film 206 is a light-transmitting material.

[0071] Some embodiments of the present invention further provide a photomask, referring to Figure 7 ,include:

[0072] A transparent substrate 201, wherein the transparent substrate 201 includes a middle region 21 and an edge region 22 surrounding the middle region 21;

[0073] A plurality of discrete shielding patterns 202 located on the surface of the middle region 21 of the transparent substrate 201;

[0074] an aerogel layer 205 located on the top surface of the shielding pattern 202;

[0075] An annular frame 204 adhered to the surface of the edge region 22 of the transparent substrate 201, the annular frame 204 surrounding the shielding pattern 202 and the aerogel layer 205;

[0076] A protective film 206 is located on the top surface of the annular frame 204 to seal the inner space of the annular frame.

[0077] In the photomask of the present application, since the aerogel layer 205 is located on the top surface of the shielding pattern 202, it will not affect or have little effect on the exposure light during the exposure process, and the formed aerogel layer 205 has the characteristics of high porosity and high adsorption, so that the formed aerogel layer 205 can absorb the ammonium ions, sulfate ions and pollution particles (particles) from the outside entering through the pores at the connection of the protective film of the photomask, and can absorb the pollution particles (particles) adsorbed by the protective film (facing the transparent substrate side), the pollution particles (particles) generated by the metal frame due to the environment, and the pollution particles (particles) generated by the embrittlement of the adhesive due to long-term ultraviolet light irradiation, and the chemicals (S, N, ammonium ions and sulfur ions, etc.) remaining in the photomask production process can be absorbed by the aerogel, thereby preventing the formation of "haze" defects on the surface of the shielding pattern 202, the surface of the middle area 21 of the photomask 201 and / or the surface of the phase shift layer during the use of the photomask, thereby improving the precision and accuracy of exposure.

[0078] In one embodiment, the aerogel layer 205 has a pore size of 1-100 nm and a density of <3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame. Under this specific parameter, the aerogel layer 205 can better adsorb ammonium ions, sulfate ions and corresponding pollution particles, while having the least impact on the exposure light.

[0079] In some embodiments, the size of the top of the aerogel layer 205 is consistent with that of the bottom, or the size of the top is smaller than that of the bottom. In a specific embodiment, the top of the aerogel layer 205 is in an upward convex arc shape.

[0080] In some embodiments, the aerogel 205 is a silicon-based aerogel or a carbon-based aerogel.

[0081] In some embodiments, the aerogel layer 205 has a pore size of 1 to 100 nm and a density of less than 3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame.

[0082] In some embodiments, the silicon-based aerogel comprises silicon dioxide aerogel.

[0083] In some embodiments, the silica aerogel has a refractive index of <1.01, a transmittance of >=80%, a pore size of 1-50 nm, and a density of <3 kg / m 3 .

[0084] In some embodiments, the method further includes an adhesive layer 201 located between the annular frame 204 and a surface of the edge region 22 of the transparent substrate 201 .

[0085] In some embodiments, the wavelength of the exposure light when using the photomask of the present application for exposure is 193nm-436nm.

[0086] It should be noted that the limitations or descriptions of the same or similar parts in some embodiments of the photomask of the present application and in some embodiments of the aforementioned photomask forming method are not repeated here. Please refer to the limitations or descriptions of the corresponding parts in some embodiments of the aforementioned photomask forming method for details.

[0087] Although the present application has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present application. Any technical personnel in this field can use the methods and technical contents disclosed above to make possible changes and modifications to the technical solution of the present application without departing from the spirit and scope of the present application. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are within the protection scope of the technical solution of the present application.

Claims

1. A method for making a photomask, characterized in that: include: Providing a transparent substrate, the transparent substrate comprising a middle area and an edge area surrounding the middle area; forming a plurality of discrete shielding patterns on the surface of the middle region of the transparent substrate; forming an aerogel layer on the top surface of the shielding pattern, wherein the coverage area of ​​the aerogel layer is equal to or smaller than the top surface area of ​​the shielding pattern; Providing an annular frame, adhering the annular frame to the edge area surface of the transparent substrate, the annular frame surrounding the shielding pattern and the aerogel layer; A protective film is formed on the top surface of the annular frame to close the inner space of the annular frame.

2. The method for manufacturing a photomask according to claim 1, wherein: The size of the top of the aerogel layer is consistent with that of the bottom, or the size of the top is smaller than that of the bottom.

3. The method for manufacturing a photomask according to claim 1 or 2, characterized in that: The top of the aerogel layer is in an upward convex arc shape.

4. The method for manufacturing a photomask according to claim 1, wherein: The aerogel is a silicon-based aerogel or a carbon-based aerogel.

5. The method for manufacturing a photomask according to claim 4, wherein: The pore size of the aerogel layer is 1-100 nm, and the density is less than 3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame.

6. The method for manufacturing a photomask according to claim 4, wherein: The silicon-based aerogel includes silicon dioxide aerogel.

7. The method for manufacturing a photomask according to claim 6, wherein: The silica aerogel has a refractive index of <1.01, a light transmittance of >=80%, a pore size of 1-50 nm, and a density of <3 kg / m 3 .

8. The method for manufacturing a photomask according to claim 1, wherein: The formation process of the aerogel layer includes a sol-gel method, a solvent deposition method or a chemical vapor deposition method.

9. The method for manufacturing a photomask according to claim 8, wherein: The process of forming the aerogel layer by the sol-gel method includes: providing a reaction tank, into which the precursor required by the sol-gel method is introduced; placing a transparent substrate with a shielding layer invertedly on top of the reaction tank so that the top surface of the shielding layer contacts the precursor; performing a sol-gel reaction process to form an initial aerogel on the top surface of the shielding layer, and applying an electric current to the shielding layer during the sol-gel reaction process; removing the transparent substrate with the initial aerogel from the reaction tank, modifying and drying the initial aerogel, and forming an aerogel.

10. The method for manufacturing a photomask according to claim 1, wherein: The aerogel layer is used to adsorb ammonium ions, sulfate ions and contamination particles to prevent haze defects from occurring on the surface of the middle area of ​​the photomask and the surface of the shielding pattern.

11. The method for manufacturing a photomask according to claim 1, wherein: The annular frame is adhered to the edge region of the transparent substrate through an adhesive layer.

12. A photomask, characterized in that: include: A transparent substrate, the transparent substrate comprising a middle area and an edge area surrounding the middle area; a plurality of discrete shielding patterns located on the surface of the middle region of the transparent substrate; The aerogel layer on the top surface of the shielding pattern is adhered to a ring-shaped frame on the surface of the edge area of ​​the transparent substrate, and the ring-shaped frame surrounds the shielding pattern and the aerogel layer; A protective film is located on the top surface of the annular frame to close the inner space of the annular frame.

13. The photomask according to claim 12, wherein: The size of the top of the aerogel layer is consistent with that of the bottom, or the size of the top is smaller than that of the bottom.

14. The photomask according to claim 12 or 13, wherein: The top of the aerogel layer is in an upward convex arc shape.

15. The photomask according to claim 12, wherein: The aerogel is a silicon-based aerogel or a carbon-based aerogel.

16. The photomask according to claim 15, wherein: The pore size of the aerogel layer is 1-100 nm, and the density is less than 3 kg / m 3 , the height of the aerogel layer is less than or equal to the height of the annular frame.

17. The photomask according to claim 16, wherein: The silicon-based aerogel includes silicon dioxide aerogel.

18. The method for manufacturing a photomask according to claim 17, wherein: The silica aerogel has a refractive index of <1.01, a light transmittance of >=80%, a pore size of 1-50 nm, and a density of <3 kg / m 3 .

19. The photomask according to claim 12, wherein: The aerogel layer is used to adsorb ammonium ions, sulfate ions and contamination particles to prevent haze defects from occurring on the surface of the middle area of ​​the photomask and the surface of the shielding pattern.

20. The photomask according to claim 12, wherein: An adhesive layer is located between the annular frame and the edge region surface of the transparent substrate.

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