Photomask and manufacturing method thereof

Abstract

The invention relates to a photomask plate and a preparation method thereof. The photomask plate comprises a light-transmitting substrate; the mask pattern is positioned on the surface of the light-transmitting substrate; one end of the photomask protection frame is fixed on the light-transmitting substrate, the other end of the photomask protection frame is connected with a protection film, the photomask protection frame completely surrounds the mask pattern area, the protection film is a photomask function film, an anti-atomization layer is arranged on the surface of the mask pattern, and the anti-atomization layer is a transparent polyimide layer. According to the photomask, the anti-fogging layer is arranged on the mask pattern and the light-transmitting substrate, the specific structure of the photomask is combined, the anti-fogging effect is enhanced, meanwhile, the interface of the functional film and the mask pattern is protected, the overall performance is improved, and the photomask is excellent in anti-fogging performance, good in optical performance, high in structural stability, mature in preparation technology and suitable for large-scale production. And the large-scale production can be realized, the quality is controllable, and the diversified requirements of different photoetching processes and environments on the photomask are met.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing technology, particularly to the field of photomasks, and more particularly to a photomask and a method for manufacturing the same. The photomask solves the problems of being easily contaminated and prone to atomization in traditional photomasks, can achieve a higher level of protection for the photomask, and improves the quality, service life and reliability of the photomask. Background Art

[0002] A photomask is a template used for batch printing circuits in the manufacturing of integrated circuit chips. Through the photolithography process, the circuit patterns on the photomask are printed in large quantities onto a silicon wafer. Therefore, any defect on the photomask will have a great impact on the yield of the chips. As semiconductor devices become more highly integrated, the size of the patterns formed on the wafers continues to decrease. In order to form such fine patterns, a more precise, higher-quality and more stable photomask is required.

[0003] A photomask is a consumable in the semiconductor industry. This is because after long-term use or exposure to a specific environment, micron- or nano-scale contaminants or crystalline layers will gradually form on the surface of the photomask, that is, fog-like defects will occur. These contaminants may be inorganic salts, organic substances or metal oxides, etc. They will absorb or scatter light, resulting in a decrease in the light transmittance of the photomask and a deterioration in the quality of the lithography pattern, and leading to a decrease in the service life of the photomask. Simply put, in the photolithography process, with the accumulation of exposure energy, the surface of the photomask is prone to adsorb and crystallize due to contaminants (SO4 2- / NH4 + / H2O). The fog-like crystals adhering to the photomask gradually grow large enough to become point defects, and then are printed onto the wafer by photolithography, which has a significant impact on the wafer yield. Fog-like defects are very common in the current photolithography process and are inversely proportional to the exposure wavelength. With the continuous development of semiconductor processes, the lithography wavelength is increasingly shortened, and the occurrence frequency of fog-like defects has increased significantly accordingly. Fog-like defects will cause distortion of the lithography pattern, a decrease in chip yield, and a decrease in the life of the photomask. The traditional anti-atomization method is to improve the cleaning method of the photomask, such as replacing high-temperature pickling and alkali washing with O3, reducing the sources of acid and alkali in the photomask atomization reaction. However, O3 is toxic, and the cost of this process is 5 to 10 times that of traditional cleaning equipment, and the cleaning speed and the removal of particulate contaminants are inferior to sulfuric acid cleaning. The sources of the substances generated in the photomask atomization reaction are not only in the cleaning stage, but also in the acid, alkali and water in the environment, which is also the reason why the traditional anti-atomization method cannot effectively avoid atomization.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] To solve the defects in the prior art, the present disclosure provides a photomask, comprising: a light-transmitting substrate; a mask pattern located on the surface of the light-transmitting substrate; a mask protection frame, one end of the mask protection frame is fixed on the light-transmitting substrate, and the other end is connected to a protective film. The mask protection frame completely surrounds the mask pattern area. The protective film is a mask functional film, and an anti-fogging layer is provided on the surface of the mask pattern. The anti-fogging layer is a transparent polyimide layer.

[0006] In some embodiments, the light-transmitting substrate is borosilicate glass or quartz.

[0007] In some embodiments, the mask pattern material is at least one of chromium or molybdenum silicide.

[0008] In some embodiments, the mask protection frame is an aluminum frame. One end of the aluminum frame is fixedly bonded to the light-transmitting substrate through an adhesive, and the other end is bonded to the protective film through an adhesive.

[0009] In some embodiments, the mask functional film is at least one of a dust-proof film and an anti-reflection film.

[0010] In some embodiments, the thickness of the anti-fogging layer is 1-50 nm, and it is uniformly distributed on the transparent substrate and the mask pattern inside the mask protection frame.

[0011] In some embodiments, the anti-fogging layer is also provided on the side of the mask functional film facing the mask pattern, and the thickness of the transparent polyimide layer on this side is 10-500 nm.

[0012] In some embodiments, the light-transmitting substrate, the mask protection frame, and the protective film enclose a closed area, and a protective gas is filled in the closed area. The protective gas is selected from one of argon, nitrogen, and helium.

[0013] Some embodiments of the present application also provide a method for manufacturing a photomask, comprising the following steps:

[0014] Provide a light-transmitting substrate, and the light-transmitting substrate is selected from borosilicate glass or quartz;

[0015] Form a mask pattern on the surface of the light-transmitting substrate, and the mask pattern material is at least one of chromium or molybdenum silicide;

[0016] Form a transparent polyimide layer on the mask pattern, and the thickness of the transparent polyimide layer is 1-50 nm;

[0017] Provide a photomask functional film, provide a photomask protection frame, fix the photomask protection frame on the light-transmitting substrate through an adhesive, and fixedly connect the other end of the photomask protection frame to the photomask functional film through an adhesive, so that the light-transmitting substrate, the photomask protection frame, and the protective film enclose a sealed area, and the photomask protection frame completely surrounds the mask pattern area.

[0018] Some embodiments of the present application also provide a method for manufacturing a photomask, including the following steps:

[0019] Provide a light-transmitting substrate, and the light-transmitting substrate is selected from borosilicate glass or quartz;

[0020] Form a mask pattern on the surface of the light-transmitting substrate, and the mask pattern material is at least one of chromium or molybdenum silicide;

[0021] Form a transparent polyimide layer on the mask pattern, and the thickness of the transparent polyimide layer is 1-50 nm;

[0022] Provide a photomask functional film, and form a transparent polyimide layer with a thickness of 10-500 nm on one side of the photomask functional film;

[0023] Provide a photomask protection frame, fix the photomask protection frame on the light-transmitting substrate through an adhesive, and fixedly connect the other end of the photomask protection frame to the photomask functional film through an adhesive, so that the light-transmitting substrate, the photomask protection frame, and the protective film enclose a sealed area, the side of the photomask functional film with the transparent polyimide layer faces the mask pattern, and the photomask protection frame completely surrounds the mask pattern area.

[0024] Some embodiments of the present application also provide a method for manufacturing a photomask, including the following steps:

[0025] Provide a light-transmitting substrate, and the light-transmitting substrate is selected from borosilicate glass or quartz;

[0026] Form a mask pattern on the surface of the light-transmitting substrate, and the mask pattern material is at least one of chromium or molybdenum silicide;

[0027] Form a transparent polyimide layer on the mask pattern, and the thickness of the transparent polyimide layer is 1-50 nm;

[0028] Provide a photomask functional film, and form a transparent polyimide layer with a thickness of 10-500 nm on one side of the photomask functional film;

[0029] A photomask protection frame is provided. The photomask protection frame is fixed on a light-transmitting substrate through an adhesive. The other end of the photomask protection frame is fixedly connected to the photomask functional film through an adhesive, so that the light-transmitting substrate, the photomask protection frame, and the protective film enclose a sealed area. The side of the photomask functional film with the transparent polyimide layer faces the mask pattern, and the photomask protection frame completely surrounds the mask pattern area.

[0030] The sealed area is evacuated and filled with a protective gas, and then sealed.

[0031] Some embodiments of the present application also provide a lithography apparatus. The lithography apparatus uses a photomask for exposure. An anti-fogging layer is provided on the surface of the mask pattern of the photomask, and the anti-fogging layer is a transparent polyimide layer.

[0032] The photomask of the present application integrates a variety of protection and optimization measures, aiming to improve the durability, stability, and optical performance of the mask. First, an anti-fogging layer (transparent polyimide layer) is provided on the surface of the mask pattern, which can effectively prevent the condensation of water vapor caused by changes in environmental humidity. This is crucial for maintaining the clarity of the mask pattern, especially when operating in a high-humidity environment. In addition, the transparent polyimide material has good optical transparency and chemical stability, and will not have a negative impact on the lithography process. The light-transmitting substrate used in the solution of the present application has excellent optical transparency and thermal stability, can withstand high temperatures without deformation, and has an extremely high transmittance in the ultraviolet range, making it suitable for the transfer of fine patterns. Using an aluminum frame and fixing it on the light-transmitting substrate through an adhesive not only provides physical protection but also ensures the sealing of the entire structure, helping to prevent external contaminants from entering the mask area, thereby extending its service life. Further, the setting of two anti-fogging layers with different thicknesses can better meet the requirements of different application scenarios. The thinner layer (1 - 50 nm) is suitable for directly covering the surface of the mask pattern to provide basic anti-fog protection; while the thicker layer (10 - 500 nm) is more suitable as an additional protective layer on the photomask functional film to enhance the overall protection ability. Filling with inert gases (such as argon, nitrogen, or helium) can effectively isolate moisture and oxygen in the air and prevent oxidation reactions. This not only extends the service life of the mask but also improves its stability under long-term storage conditions. It can be seen that such a photomask can provide higher resolution and more stable imaging effects during the lithography process, is particularly suitable for manufacturing high-performance semiconductor devices, reduces defects caused by contamination or environmental factors, and improves the yield of products.

[0033] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. Description of the Drawings

[0034] The accompanying drawings herein are incorporated into and form a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0035] Figure 1 Schematic diagram of a photomask structure in some embodiments of the present application;

[0036] Figure 2 Schematic diagram of a photomask structure in some embodiments of the present application.

[0037] Explanation of reference numerals: 1 - light-transmitting substrate; 2 - mask pattern; 3 - binder; 4 - photomask protection frame; 5 - transparent polyimide layer; 6 - protective film. Detailed implementation manners

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar structures, and thus their detailed descriptions will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0039] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of an icon to another component, these terms are used in this specification only for convenience, for example, according to the directions of the examples described in the accompanying drawings. It can be understood that if the device of the icon is turned upside down, the component described as "upper" will become the component described as "lower". When a structure is "on" another structure, it may mean that a structure is integrally formed on another structure, or that a structure is "directly" disposed on another structure, or that a structure is "indirectly" disposed on another structure through another structure.

[0040] The terms "a", "an", "the", "said" and "at least one" are used to indicate the existence of one or more elements / components / etc.; the terms "comprising" and "having" are used to mean an open inclusion and mean that there may be additional elements / components / etc. in addition to the listed elements / components / etc.; the terms "first" and "second" are used only as labels and are not a limitation on the quantity of their objects.

[0041] In one embodiment, please refer to Figure 1 , Figure 1The following is a schematic diagram of a photomask structure in some embodiments of the present invention, including: a transparent substrate 1; a mask pattern 2 located on the surface of the transparent substrate; a mask protection frame 3, one end of the mask protection frame 3 is fixed on the transparent substrate 1, and the other end is connected to a protective film 6. The mask protection frame 3 completely surrounds the area of the mask pattern 2. The protective film 6 is a mask functional film. An anti-fogging layer 5 is provided on the surface of the mask pattern, and the anti-fogging layer is a transparent polyimide layer. Due to its excellent heat resistance, mechanical properties, good chemical stability, moisture and heat resistance, radiation resistance, good dielectric properties, low temperature resistance, low expansion coefficient, flame retardancy and other characteristics, the polyimide film is called the "golden film" and can be widely used in space technology, motors, electrical insulation, FPC (flexible printed circuit board), PTC electrothermal film, TAB (pressure-sensitive tape substrate), aerospace, aviation, computer and other industries. In an embodiment of this application, it is creatively proposed to use a transparent polyimide film as the anti-fogging layer. After experimental verification, this structure can resist mechanical damage during photomask cleaning, be compatible with wet / dry photomask cleaning processes, inhibit pollutant adsorption, and block and separate ammonium-containing substances remaining or internally decomposed after photoresist stripping and cleaning processes. It greatly inhibits the adsorption and crystallization of fog-like pollutants such as ammonium sulfate, and reduces the occurrence of fog-like defects.

[0042] The transparent substrate 1 is the carrier of the photomask and plays an important role in the accuracy and quality of the photomask product. The material of the transparent substrate can be a quartz substrate, a glass substrate, an organic substrate, etc. Among them, the glass substrate includes synthetic quartz, borosilicate glass, and soda glass, etc. Quartz has obvious advantages in physical properties such as light transmittance, thermal expansion, and hardness, making it have a relatively large tolerance to the influence of the natural environment such as temperature, humidity, and pressure. The quartz substrate photomask can maintain chemical stability and high penetration under the irradiation of a specific wavelength light source. In addition, borosilicate glass also has high thermal stability and is also commonly used in photomask substrates. In some embodiments, the transparent substrate 1 is borosilicate glass or quartz. The surface roughness of the transparent substrate affects the deposition of subsequent coatings. In an embodiment of this application, the transparent substrate is cleaned and subjected to two-step polishing before use. The cleaning is conventional cleaning, such as water washing, organic solvent washing, etc. The two-step polishing process is mechanical polishing and chemical polishing. Among them, mechanical polishing is to use abrasive for grinding and polishing, and chemical polishing is to soak and treat with a HF / HNO3 mixed solution with a volume ratio of 1:3 for 120 s.

[0043] The mask pattern 2 located on the surface of the light-transmitting substrate is a light-shielding film. The materials of the light-shielding film mainly include: metal chromium, silicon, iron oxide, molybdenum silicide, etc. The selection of the light-shielding film materials mainly depends on factors such as the pattern accuracy, transmittance, and chemical resistance of the product. Among them, chromium is the most commonly used light-shielding film material. This is because chromium has good optical properties and physical and chemical stability, has a high absorption rate for ultraviolet light (especially the commonly used lithography wavelength), can form clear light and dark contrasts, thus accurately transmitting pattern information during the lithography process, making the boundary between the light-transmitting area and the light-blocking area of the mask pattern distinct, ensuring the pattern resolution during exposure, and at the same time having high hardness and wear resistance, being able to withstand the slight friction and collision that may occur during the lithography process, avoiding damage to the mask pattern. It has good chemical stability, is not easily oxidized in the air, and can maintain good performance for a long time. In addition, chromium has good adhesion to the light-transmitting substrate (such as borosilicate glass, quartz), and can be firmly attached to the substrate surface through appropriate preparation processes, ensuring the stability of the mask pattern during long-term use. In addition, silicon is also a light-shielding film material, which is suitable for manual alignment operations, but its microfabrication performance is not as good as that of chromium, and it is mostly used in low-end hard photomasks. For the pattern of the light-shielding film, it can be designed according to the specific circuit pattern, that is, the target pattern to be transferred. In some embodiments, the material of the mask pattern 2 is at least one of chromium or molybdenum silicide. When the mask pattern material is one kind, the mask pattern is a single-layer structure; when the mask pattern material is two kinds, the mask pattern is a two-layer stacked structure formed by a Cr layer and a MoSi layer, such as the mask pattern is a MoSi layer stacked on the light-transmitting substrate in sequence and a Cr layer located on the MoSi layer.

[0044] The preparation of the mask pattern is carried out through mask layer deposition, lithography, and etching. Taking chromium as the mask pattern material as an example, a chromium layer is usually formed on the surface of the light-transmitting substrate by sputtering deposition process. High-energy ions are used to bombard the chromium target, causing chromium atoms to sputter out and deposit on the substrate surface. During the deposition process, parameters such as sputtering power, sputtering time, the distance between the target and the substrate, and vacuum degree need to be precisely controlled to ensure the thickness uniformity and surface flatness of the chromium layer. For example, in order to obtain a chromium layer with uniform thickness, the sputtering power needs to be kept stable, generally controlled between 100 and 500 W; the vacuum degree is maintained at 10 -3 ~10 -4Pa to reduce the contamination of the chromium layer by impurities in the air. A photoresist is coated on the deposited chromium layer, and a photoresist template with the required mask pattern is formed through photolithography processes such as exposure and development. Then, the chromium layer is etched using dry etching (such as reactive ion etching, RIE) or wet etching processes to remove the unprotected parts by the photoresist, thereby forming an accurate mask pattern on the substrate. Dry etching has high etching accuracy and anisotropy, enabling the etching of fine lines (such as sub-micron level); wet etching has the advantages of fast etching speed and simple equipment, but relatively low etching accuracy. In actual production, the appropriate etching process needs to be selected according to the accuracy requirements of the mask pattern. The thickness of the chromium layer of the mask pattern is usually controlled according to the requirements of the photolithography process, generally between 100 and 500 nm. A thicker chromium layer can improve the light-blocking ability but increase the etching difficulty; a thinner chromium layer is relatively easy to etch but may affect the light-shielding effect. By precisely controlling the sputtering deposition time and rate, accurate control of the chromium layer thickness can be achieved.

[0045] One end of the reticle protection frame 3 is fixed on the transparent substrate 1, and the other end is connected to the protective film 6. The reticle protection frame 3 completely surrounds the mask pattern 2 area. In some embodiments, the reticle protection frame is made of an aluminum frame. Aluminum has the advantages of low density, high strength, easy processing, and low cost. It can reduce the overall weight of the photomask, facilitating handling and installation. At the same time, aluminum has good mechanical strength and rigidity, which can effectively support the protective film and maintain the overall structural stability of the photomask. Aluminum has good corrosion resistance, and a dense aluminum oxide film is easily formed on the surface in the air, which can block the intrusion of moisture and corrosive gases and extend the service life of the reticle protection frame. The shape of the aluminum frame is usually rectangular or circular, customized according to the sizes of the transparent substrate and the mask pattern. The thickness and width of the frame body need to be designed according to the size and usage requirements of the photomask to ensure sufficient strength and rigidity. For example, for a larger-sized photomask (such as a square photomask with a side length of 300 mm), the thickness of the aluminum frame is generally 5 - 10 mm, and the width is 10 - 20 mm to prevent deformation during handling and use. In addition, the inner edge of the aluminum frame needs to be precisely processed to ensure complete surrounding of the mask pattern area and a flat and smooth bonding part with the transparent substrate and the protective film to ensure the sealing and reliability of the bonding. To improve the overall rigidity of the aluminum frame, ribs can be set on the frame body or a hollow structure can be adopted to reduce the weight without reducing the strength.

[0046] The binder should have good bonding strength, heat resistance, chemical resistance and sealing performance. Commonly used binders include epoxy resin adhesives, silicone rubber adhesives, etc. Epoxy resin adhesives have relatively high bonding strength and heat resistance (able to withstand temperatures of 100 - 200 °C), and are suitable for occasions requiring high-strength bonding; silicone rubber adhesives have good elasticity and sealing performance, can adapt to certain temperature changes and mechanical vibrations, and prevent the leakage of protective gas in the sealed area. After bonding, the sealing performance of the bonded part needs to be detected (such as helium leak detection method) to ensure the long-term stability of the protective gas.

[0047] In one embodiment, the protective film is a dust-proof film. The dust-proof film blocks external dust particles from entering the sealed area, preventing dust from adhering to the surface of the mask pattern and affecting the lithography accuracy. The dust-proof film usually adopts microporous filter materials, such as polytetrafluoroethylene (PTFE) film, polypropylene (PP) film, etc. The pore size is selected according to the size of the dust particles to be filtered. The dust-proof film has good air permeability, can allow the protective gas to pass through, and effectively blocks dust particles, and its filtration efficiency can reach more than 99.9%.

[0048] In one embodiment, the protective film is an antireflection film. The function of the antireflection film is to reduce the reflection of light on the surface of the protective film, improve the light transmittance, and thus enhance the exposure effect. The antireflection film usually consists of multiple layers of optical thin films with different refractive indices, such as a multi-layer film structure of silicon dioxide (SiO₂) and titanium dioxide (TiO₂). By reasonably designing the thickness and refractive index of each layer of thin film, the lowest reflectivity can be achieved at a specific exposure wavelength.

[0049] According to different usage environments and lithography process requirements, a single-function film or a combination of multiple-function films can be selected. In an environment with more dust, a dust-proof film is preferably selected to ensure the cleanliness of the mask pattern surface; in deep ultraviolet lithography processes with high requirements for exposure efficiency, an antireflection film can be used to improve the light transmittance; for complex environments with both dust pollution and light reflection problems, a dust-proof film and an antireflection film can be used in combination to form a composite function film. When used in combination, attention should be paid to the compatibility between the two function films to ensure firm bonding and no impact on their respective performances. For example, the antireflection film can be set on the side facing the light source, the dust-proof film can be set on the side facing the outside, and they are connected to the photomask protection frame through a binder in the middle to form a multi-layer protection structure.

[0050] The anti-fogging layer is set as a transparent polyimide layer, which has good transparency and anti-fogging performance. The anti-fogging layer is evenly distributed on the transparent substrate and the mask pattern inside the mask protection frame, with a thickness of 1 - 50 nm. The thinner anti-fogging layer in contact with the mask pattern can completely cover the mask pattern without affecting the optical performance, effectively isolating external sulfate ions, ammonium ions, water, etc., and inhibiting the deposition and formation of impurities such as ammonium sulfate that cause foggy defects on the mask pattern, having good anti-fogging ability. During the preparation process, the thickness of the transparent polyimide layer is controlled by methods such as spin coating, spraying, or chemical vapor deposition to ensure its uniformity. At the same time, a transparent polyimide layer with a thickness of 10 - 500 nm can also be deposited on the side of the mask pattern facing the mask function film. This thicker anti-fogging layer can, on the one hand, further enhance the absorption and blocking of moisture, and on the other hand, protect the interface between the mask function film and the mask pattern, reducing the influence of the external environment on the interface. At the same time, the setting of the two transparent polyimide layers can achieve a synergistic anti-fogging effect, reducing the fogging phenomenon and pattern defects caused by dust adsorption. Further, the surface of the transparent polyimide layer can also be modified, such as ultraviolet ozone treatment, plasma treatment, etc., to improve its hydrophilicity or hydrophobicity. Hydrophilic treatment can enhance the ability to absorb and evenly distribute moisture and is suitable for high-humidity environments; hydrophobic treatment can reduce the adhesion of moisture on the surface and is suitable for humid but easily condensable environments. Through surface modification, the performance of the anti-fogging layer can be further optimized to meet the requirements of different usage scenarios. In some embodiments, the thickness of the anti-fogging layer is 1 - 50 nm and is evenly distributed on the transparent substrate and the mask pattern inside the mask protection frame; in another embodiment, the anti-fogging layer is also provided on the side of the mask function film facing the mask pattern, and the thickness of the transparent polyimide layer on this side is 10 - 500 nm.

[0051] In some embodiments, the transparent substrate, the mask protection frame, and the protective film enclose a sealed area. This sealed area can ensure that there is no leakage at the bonding parts between the mask protection frame and the transparent substrate and the protective film. At the same time, the protective film itself has good gas barrier performance, reducing the occurrence of internal impurity gases and also inhibiting the generation of foggy defects to a certain extent. The size of the sealed area is designed according to the size of the mask pattern and the structure of the mask protection frame to ensure that the mask pattern is completely located within the sealed area and there is enough space around to accommodate the protective gas. A protective gas is filled in the sealed area, and the protective gas is selected from one of argon, nitrogen, and helium. These gases are all inert gases with stable chemical properties and are not easily chemically reactive with the mask pattern, anti-fogging layer, etc. For general semiconductor manufacturing scenarios, nitrogen is a commonly used choice due to its low cost and stable performance; in cases where higher heat dissipation requirements or rapid gas replacement are needed, helium can be selected; in special scenarios with higher requirements for gas density and temperature stability, argon is more suitable.

[0052] When preparing the photomask, first evacuate the enclosed area to a vacuum level below 1×10-3Pa to remove as much air and moisture as possible from the area. Then slowly inject the selected protective gas into the enclosed area through a gas injection device, and control the injection pressure to be slightly higher than atmospheric pressure (such as 1.1-1.2atm) to form a positive pressure environment to prevent external gas from entering. After the injection is completed, a high-precision sealing process (such as laser welding and glue sealing) is used to seal the gas injection hole to ensure the long-term sealing of the enclosed area. During use, the gas pressure and composition in the enclosed area can be regularly tested. If the pressure drops or the impurity gas content increases, replenish the gas or replace the photomask in time.

[0053] In another embodiment, see Figure 2 , Figure 2 The figure shows a schematic diagram of the photomask structure in some embodiments of the present invention, including: a transparent substrate 1; a mask pattern 2 located on the surface of the transparent substrate; a mask protection frame 3, one end of the mask protection frame 3 is fixed on the transparent substrate 1, and the other end is connected to a protective film 6, the mask protection frame 3 completely surrounds the mask pattern 2 area, the protective film 6 is an anti-reflection film, and an anti-fogging layer 5 is provided on the surface of the mask pattern, and the anti-fogging layer is a transparent polyimide layer.

[0054] Some embodiments of the present application also provide a method for preparing a photomask, comprising the following steps:

[0055] Providing a light-transmitting substrate 1, wherein the light-transmitting substrate is borosilicate glass; performing mechanical polishing and chemical polishing on the light-transmitting substrate, and then washing and drying;

[0056] A mask pattern 2 is formed on the surface of the light-transmitting substrate 1, wherein the mask pattern is formed by stacking a MoSi layer and a chromium layer thereon;

[0057] A transparent polyimide layer 5 is formed on the mask pattern 2, wherein the thickness of the transparent polyimide layer is 1-50 nm; the transparent polyimide layer is prepared by spraying with a coating machine, wherein the spraying pressure is 2.0-5.0 kg / cm 2 The spraying speed is 3500-6500 mm / min, the viscosity of the polyimide is 5-20 cp, the spraying time is 5-20 s, and the coating is dried and solidified after spraying, wherein the drying temperature is 50-120°C and the drying time is 60 s. The coating and curing are performed multiple times according to the required thickness to obtain a transparent polyimide layer of the required thickness.

[0058] Provide a photomask functional film 6, provide a photomask protection frame 4, fix the photomask protection frame on the transparent substrate through an adhesive 3, and fixedly connect the other end of the photomask protection frame to the photomask functional film through the adhesive 3, so that the transparent substrate, the photomask protection frame, and the protective film enclose a sealed area, and the photomask protection frame completely surrounds the mask pattern area.

[0059] Some embodiments of the present application also provide a method for manufacturing a photomask, including the following steps:

[0060] Provide a transparent substrate 1, and the transparent substrate is quartz; perform mechanical polishing and chemical polishing on the transparent substrate, and then wash and dry it;

[0061] Form a mask pattern 2 on the surface of the transparent substrate, and the mask pattern material is at least one of chromium or molybdenum silicide;

[0062] Form a transparent polyimide layer on the mask pattern, and the thickness of the transparent polyimide layer is 1 - 50 nm; the transparent polyimide layer is prepared by spraying with a coater, wherein the spraying pressure is 2.0 - 5.0 kg / cm 2 , the spraying speed is 3500 - 6500 mm / min, the viscosity of the polyimide is 5 - 20 cp, the spraying time is 5 - 20 S, and after spraying, it is dried and cured, wherein the drying temperature is 50 - 120 °C, the drying time is 60 s, and spraying and curing are performed multiple times according to the required thickness to obtain a transparent polyimide layer with the required thickness.

[0063] Provide a photomask functional film, and form a transparent polyimide layer with a thickness of 100 - 500 nm on one side of the photomask functional film; the transparent polyimide layer is prepared by roll coating with a coater, and the coating pressure for roll coating is 0.5 - 3 kg / cm 2 , the transmission speed is 1000 - 3500 mm / min, the viscosity of the polyimide is 15 - 40 cp, and after roll coating, it is dried and cured, wherein the drying temperature is 80 - 120 °C, the drying time is 60 s, and spraying and curing are performed multiple times according to the required thickness to obtain a transparent polyimide layer with the required thickness.

[0064] Provide a photomask protection frame, fix the photomask protection frame on the transparent substrate through an adhesive, and fixedly connect the other end of the photomask protection frame to the photomask functional film through the adhesive, so that the transparent substrate, the photomask protection frame, and the protective film enclose a sealed area, the side of the photomask functional film with the transparent polyimide layer faces the mask pattern, and the photomask protection frame completely surrounds the mask pattern area.

[0065] Some embodiments of the present application also provide a method for manufacturing a photomask, including the following steps:

[0066] Provide a light-transmitting substrate 1, where the light-transmitting substrate is quartz; perform mechanical polishing and chemical polishing on the light-transmitting substrate, then wash it with water and dry it;

[0067] Form a mask pattern 2 on the surface of the light-transmitting substrate, and the mask pattern material is one of chromium or molybdenum silicide;

[0068] Form a transparent polyimide layer on the mask pattern, and the thickness of the transparent polyimide layer is 1 - 50 nm; the transparent polyimide layer is prepared by spraying with a coater, where the spraying pressure is 2.0 - 5.0 kg / cm 2 , the spraying speed is 3500 - 6500 mm / min, the viscosity of the polyimide is 5 - 20 cp, the spraying time is 5 - 20 S, and after spraying, it is dried and cured, where the drying temperature is 50 - 120 °C and the drying time is 60 s. Spray and cure multiple times according to the required thickness to obtain a transparent polyimide layer with the required thickness.

[0069] Provide a photomask functional film, and form a transparent polyimide layer with a thickness of 100 - 500 nm on one side of the photomask functional film; the transparent polyimide layer is prepared by roll coating with a coater, and the coating pressure for roll coating is 0.5 - 3 kg / cm 2 , the transmission speed is 1000 - 3500 mm / min, the viscosity of the polyimide is 15 - 40 cp, and after roll coating, it is dried and cured, where the drying temperature is 80 - 120 °C and the drying time is 60 s. Spray and cure multiple times according to the required thickness to obtain a transparent polyimide layer with the required thickness.

[0070] Provide a photomask protection frame, fix the photomask protection frame on the light-transmitting substrate through an adhesive, and the other end of the photomask protection frame is fixedly connected to the photomask functional film through an adhesive, so that the light-transmitting substrate, the photomask protection frame, and the protective film enclose a closed area. The side of the photomask functional film with the transparent polyimide layer faces the mask pattern, and the photomask protection frame completely surrounds the mask pattern area.

[0071] Vacuum the closed area, and the vacuum degree needs to reach below 1×10 - 3 Pa. Then, slowly inject the selected protective gas nitrogen into the closed area through a gas injection device, and control the injection pressure slightly higher than the atmospheric pressure to form a positive pressure environment to prevent external gas from entering. After the injection is completed, seal the gas injection hole to ensure the long-term sealing of the closed area.

[0072] Some embodiments of the present application also provide a method for preparing a photomask, including the following steps:

[0073] Provide a light-transmitting substrate 1, where the light-transmitting substrate is quartz; perform mechanical polishing and chemical polishing on the light-transmitting substrate, then wash it with water and dry it;

[0074] A mask pattern 2 is formed on the surface of the light-transmitting substrate, and the mask pattern material is one of chromium or molybdenum silicide;

[0075] A transparent polyimide layer is formed on the mask pattern, and the thickness of the transparent polyimide layer is 30 nm; the transparent polyimide layer is prepared by spraying with a coater, wherein the spraying pressure is 4.0 kg / cm 2 , the spraying speed is 4500 mm / min, the viscosity of the polyimide is 10 cp, the spraying time is 10 s, and after spraying, it is dried and cured, wherein the drying temperature is 70 °C and the drying time is 60 s. Spraying and curing are carried out multiple times according to the required thickness to obtain a 30-nm transparent polyimide layer.

[0076] A photomask functional film is provided, and a 400-nm-thick transparent polyimide layer is formed on one side of the photomask functional film; the transparent polyimide layer is prepared by roll coating with a coater, and the coating pressure for roll coating is 1 kg / cm 2 , the driving speed is 1500 mm / min, the viscosity of the polyimide is 40 cp, and after roll coating, it is dried and cured, wherein the drying temperature is 120 °C and the drying time is 60 s. Spraying and curing are carried out multiple times according to the required thickness to obtain a 400-nm transparent polyimide layer.

[0077] A photomask protection frame is provided, and the photomask protection frame is fixed on the light-transmitting substrate through an adhesive. The other end of the photomask protection frame is fixedly connected to the photomask functional film through an adhesive, so that the light-transmitting substrate, the photomask protection frame, and the protective film enclose a sealed area. The side of the photomask functional film with the transparent polyimide layer faces the mask pattern, and the photomask protection frame completely surrounds the mask pattern area.

[0078] The sealed area is evacuated, and the vacuum degree needs to reach 0.5×10-3 Pa. Then, the selected protective gas argon is slowly injected into the sealed area through a gas injection device, and the injection pressure is controlled slightly higher than the atmospheric pressure to form a positive pressure environment to prevent external gas from entering. After the injection is completed, the gas injection hole is sealed to ensure the long-term sealing of the sealed area.

[0079] Some embodiments of the present application also provide a lithography device. The lithography device uses a photomask for exposure, and an anti-fogging layer is provided on the surface of the mask pattern of the photomask, and the anti-fogging layer is a transparent polyimide layer.

[0080] The photomask of the present application is applicable to lithography processes in fields such as semiconductor manufacturing, flat panel display, and microelectromechanical systems (MEMS), can meet the requirements of high-end lithography processes, and provides key support for the manufacturing of advanced integrated circuits. With the continuous development of semiconductor and micro-nano manufacturing technologies, the demand for high-performance photomasks will continue to grow, and this technical solution has broad application prospects and market potential.

[0081] The above has introduced in detail a photomask and a method for preparing the same. The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the art to which the present invention pertains, without departing from the concept of the present invention, its architecture form can be flexibly changed and a series of products can be derived. Just making several simple deductions or substitutions should be regarded as belonging to the patent protection scope determined by the claims submitted by the present invention.

[0082] Those skilled in the art will readily conceive of other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. The present disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

Claims

1. A photomask, comprising: Light-transmissive substrate; Mask pattern located on the surface of the light-transmissive substrate; Mask protection frame, one end of the mask protection frame is fixed on the light-transmissive substrate, and the other end is connected to a protective film. The mask protection frame completely surrounds the mask pattern area. The protective film is a mask functional film, characterized in that, An anti-fogging layer is provided on the surface of the mask pattern, and the anti-fogging layer is a transparent polyimide layer.

2. The photomask according to claim 1, wherein The light-transmissive substrate is borosilicate glass or quartz.

3. The photomask according to claim 1, wherein The mask pattern material is at least one of chromium or molybdenum silicide.

4. The photomask according to claim 1, characterized in that, The mask protection frame is an aluminum frame. One end of the aluminum frame is fixedly bonded to the light-transmissive substrate through an adhesive, and the other end is bonded to the protective film through an adhesive.

5. The photomask according to claim 1, characterized in that, The mask functional film is at least one of a dust-proof film and an anti-reflection film.

6. The photomask according to claim 1, wherein The thickness of the anti-fogging layer is 1-50 nm, and it is evenly distributed on the transparent substrate and the mask pattern inside the mask protection frame.

7. The photomask according to claim 6, wherein The anti-fogging layer is also provided on the side of the mask functional film facing the mask pattern, and the thickness of the transparent polyimide layer on this side is 10-500 nm.

8. The photomask according to any one of claims 1-7, characterized in that, The light-transmissive substrate, the mask protection frame, and the protective film enclose a sealed area, and a protective gas is filled in the sealed area. The protective gas is selected from one of argon, nitrogen, and helium.

9. A method for preparing a photomask according to any one of claims 1-8, characterized in that, Including the following steps: Provide a light-transmissive substrate, and the light-transmissive substrate is selected from borosilicate glass or quartz; Form a mask pattern on the surface of the light-transmissive substrate, and the mask pattern material is at least one of chromium or molybdenum silicide; Form a transparent polyimide layer on the mask pattern, and the thickness of the transparent polyimide layer is 1-50 nm; Provide a mask functional film, and form a transparent polyimide layer with a thickness of 10-500 nm on one side of the mask functional film; Provide a mask protection frame, fix the mask protection frame on the light-transmissive substrate through an adhesive, and the other end of the mask protection frame is fixedly connected to the mask functional film through an adhesive, so that the light-transmissive substrate, the mask protection frame, and the protective film enclose a sealed area. The side of the mask functional film with the transparent polyimide layer faces the mask pattern, and the mask protection frame completely surrounds the mask pattern area; Vacuum the sealed area and inject a protective gas, and then seal it.

10. A lithographic apparatus, characterized in that, The lithography equipment uses the photomask as described in any one of claims 1-8 for exposure.

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