Photoetching mask protective film for semiconductor and preparation method thereof

Abstract

The invention relates to the field of semiconductor protection films, and discloses a photoetching mask protection film for a semiconductor and a preparation method of the photoetching mask protection film. The photoetching mask protective film for the semiconductor is prepared from the following raw materials in parts by weight: 20-30 parts of fluorinated ethylene propylene dispersion liquid, 18-28 parts of polytetrafluoroethylene dispersion liquid, 12-20 parts of a heat-resistant agent, 4.5-8.5 parts of an antistatic agent and 1-3 parts of an antioxidant, the heat-resistant agent is prepared from perfluorooctyl ethyl acrylate, alkenyl phenyl glycidyl ether, a solvent and a catalyst through a reaction; the preparation method comprises the following steps: S1, uniformly mixing all the components to prepare dispersion liquid; and S2, carrying out film casting on the dispersion liquid, and drying. The protective film prepared by the invention is applied to a semiconductor photoetching process, has relatively good light and heat resistance, antistatic property and light transmittance, can play a relatively good protection role on a mask plate, and meanwhile, improves the precision of a photoetching pattern.

Description

Technical Field

[0001] The present application relates to the field of semiconductor protective films, and more specifically, to a protective film for a photolithography mask for semiconductors and a preparation method thereof. Background Art

[0002] In the semiconductor lithography process, the light source needs to pass through the photolithography mask to map the circuit structure onto the photoresist in order to achieve circuit construction at the microscale. The mask protective film is a transparent film that covers the surface of the mask during production to protect the pattern on the mask surface from physical damage during handling or use, prevent dust and other contaminants from falling on the mask surface, and at the same time prevent chemical reagents or corrosive gases from reacting with the mask surface, avoiding affecting the accuracy and stability of pattern transfer in the semiconductor lithography process.

[0003] Currently, the commonly used mask protective films are divided into two types: hard mask protective films and soft mask protective films. Hard mask protective films are usually composed of materials with high corrosion resistance and hardness, such as Si3N4, SiO2, polysilicon, etc. Soft mask protective films are composed of polymer materials, and fluororesins, such as polytetrafluoroethylene and other F-containing polymers, are widely used in mask protective films.

[0004] However, due to the excellent insulation properties of fluororesins, static charges are likely to accumulate during use, causing periodic discharges on the mask surface, and the lithography pattern may be damaged due to the heat generated by the discharge; moreover, under the irradiation conditions of high-energy ultraviolet light in lithography, the protective film is prone to aging due to the thermal effect, resulting in a reduction in the accuracy of the lithography pattern. Summary of the Invention

[0005] In order to solve the problems of low light and heat resistance and antistatic properties of the protective film for a photolithography mask for semiconductors, the present application provides a protective film for a photolithography mask for semiconductors and a preparation method thereof.

[0006] In a first aspect, the present application provides a protective film for a photolithography mask for semiconductors, adopting the following technical solution: A protective film for a photolithography mask for semiconductors is prepared from the following raw materials in parts by weight: Perfluoroethylenepropylene dispersion 20 - 30 parts Polytetrafluoroethylene dispersion 18 - 28 parts Heat-resistant agent 12 - 20 parts Antistatic agent 4.5 - 8.5 parts Antioxidant 1 - 3 parts; The heat-resistant agent is prepared by reacting perfluorooctylethyl acrylate, alkenyl phenyl glycidyl ether, a solvent and a catalyst.

[0007] By adopting the above technical solution, the protective film in the present application uses perfluorinated ethylene-propylene copolymer dispersion and polytetrafluoroethylene dispersion as the main raw materials. The perfluorinated ethylene-propylene copolymer dispersion has good corrosion resistance and transparency, and the polytetrafluoroethylene dispersion has good light and heat resistance. The compounding can improve the light transmittance, corrosion resistance and light and heat resistance of the protective film. However, after the perfluorinated ethylene-propylene copolymer dispersion and the polytetrafluoroethylene dispersion are compounded, the insulation is good, which reduces the antistatic performance of the protective film. The static charges generated on the protective film are easy to accumulate and then cause periodic discharge, so that the lithographic pattern may be damaged due to the discharge heat; and under the irradiation condition of high-energy ultraviolet light for lithography, the protective film is still prone to aging due to the thermal effect. Therefore, the present application further introduces an antistatic agent and a heat-resistant agent prepared by reacting perfluorooctylethyl acrylate, alkenylphenyl glycidyl ether, a solvent and a catalyst into the main raw materials. The heat-resistant agent and the antistatic agent have a good synergistic effect. The antistatic agent is stably dispersed in the system of the heat-resistant agent, perfluorinated ethylene-propylene copolymer dispersion and polytetrafluoroethylene dispersion, so that the protective film has a relatively stable antistatic performance while having good light and heat stability, avoiding the problem of damage to the lithographic pattern caused by electrostatic discharge or ultraviolet light irradiation thermal reaction, being applicable to the protection of lithographic masks, and at the same time the moderate light transmittance can also improve the accuracy of the lithographic pattern.

[0008] Preferably, the heat-resistant agent is prepared from the following raw materials in parts by weight: Perfluorooctylethyl acrylate 20 - 30 parts Alkenylphenyl glycidyl ether 6 - 12 parts Solvent 35 - 45 parts Catalyst 0.05 - 0.15 parts.

[0009] By adopting the above technical solution, the heat-resistant agent of the present application is prepared by carrying out a polymerization reaction of perfluorooctylethyl acrylate and alkenylphenyl glycidyl ether in a solvent environment under the catalysis of a catalyst, introducing phenyl and ether groups into perfluorooctylethyl acrylate. The prepared heat-resistant agent can be intertwined and dispersed with perfluorinated ethylene-propylene copolymer dispersion and polytetrafluoroethylene dispersion. Under the action of the phenyl and ether groups, the molecular chain segments can fully stretch and form a certain steric hindrance, which is beneficial to the uniform dispersion of the antistatic agent in the system, and can have a good synergistic effect with the long-chain perfluoro groups of perfluorooctylethyl acrylate, further improving the light and heat resistance and flexibility of the prepared protective film while enhancing the antistatic property of the protective film, and preventing the antistatic agent from migrating during the ultraviolet light irradiation thermal reaction process, resulting in a reduction in the antistatic property of the protective film.

[0010] Preferably, the alkenylphenyl glycidyl ether is 4-vinylphenyl glycidyl ether and / or diisopropenylphenyl glycidyl ether.

[0011] By adopting the above technical solution, 4-vinylphenyl glycidyl ether and / or diisopropenylphenyl glycidyl ether, as alkenylphenyl glycidyl ethers, can stably polymerize with perfluorooctylethyl acrylate to form a stable heat-resistant structure, improving the light and heat stability while enhancing the antistatic property.

[0012] Preferably, the solvent is any one of N,N-dimethylacetamide, N-methylpyrrolidone, and N,N-dimethylformamide; the catalyst is benzoyl peroxide.

[0013] By adopting the above technical solution, N,N-dimethylacetamide, N-methylpyrrolidone, and N,N-dimethylformamide as solvents have good dissolution properties, which can ensure the full dispersion of reactants. And benzoyl peroxide as a catalyst can efficiently initiate the reaction at an appropriate temperature, improving the reaction efficiency and reaction stability.

[0014] Preferably, the heat-resistant agent is prepared by the following steps: Add perfluorooctylethyl acrylate and alkenylphenyl glycidyl ether to the solvent, disperse them, then add the catalyst, raise the temperature to 70 - 85 °C, react for 1 - 3 h, and remove the solvent after the reaction is completed to obtain the heat-resistant agent.

[0015] By adopting the above technical solution, controlling the optimal post-reaction temperature and reaction time enables the reaction of perfluorooctylethyl acrylate and alkenylphenyl glycidyl ether in the solvent, which can improve the reaction efficiency of perfluorooctylethyl acrylate and alkenylphenyl glycidyl ether and enhance the light and heat stability of the prepared protective film.

[0016] Preferably, the antistatic agent consists of a dimethyldiallylammonium chloride-acrylamide copolymer and 1-ethyl-3-methylimidazolium ethyl sulfate with a weight ratio of 1:(2 - 3).

[0017] By adopting the above technical solution, using a dimethyldiallylammonium chloride-acrylamide copolymer and 1-ethyl-3-methylimidazolium ethyl sulfate with an optimal weight ratio as the antistatic agent can be evenly dispersed in the system composed of the heat-resistant agent, perfluoroethylenepropylene dispersion, and polytetrafluoroethylene dispersion, and is not prone to problems such as diffusion and migration, having good light and heat stability and antistatic performance.

[0018] Preferably, the antioxidant is antioxidant 1010 and / or antioxidant 168.

[0019] By adopting the above technical solution, antioxidant 1010 and / or antioxidant 168 can effectively inhibit the thermal decomposition and oxidative degradation of perfluoroethylene-propylene copolymer dispersion, polytetrafluoroethylene dispersion, heat-resistant agent and antistatic agent under high-energy irradiation conditions, thereby improving the light and heat stability and service life of the protective film.

[0020] Preferably, the thickness of the photolithography mask protective film is 5-12 μm.

[0021] By adopting the above technical solution, the protective film with a preferable thickness has good light transmission performance in semiconductor lithography process, and at the same time maintains sufficient mechanical strength to protect the surface pattern of the mask from physical damage, improving the accuracy of the lithography pattern.

[0022] In a second aspect, the present application provides a preparation method for a photolithography mask protective film for semiconductors, adopting the following technical solution: A preparation method for a photolithography mask protective film for semiconductors includes the following steps: S1. Add perfluoroethylene-propylene copolymer dispersion, polytetrafluoroethylene dispersion, heat-resistant agent, antistatic agent and antioxidant into a mixing device, disperse evenly to obtain a dispersion; S2. Cast the dispersion into a film and dry it to obtain a photolithography mask protective film for semiconductors.

[0023] By adopting the above technical solution, in the preparation process, first, perfluoroethylene-propylene copolymer dispersion, polytetrafluoroethylene dispersion, heat-resistant agent, antistatic agent and antioxidant are fully mixed to form a uniform dispersion. Then the dispersion is cast into a film and dried, and the obtained protective film has good film-forming uniformity.

[0024] Preferably, the dispersion temperature in step S1 is 45-55 °C, and the drying in step S2 is divided into two stages. The drying temperature in the first stage is 90-110 °C, and the drying temperature in the second stage is 120-140 °C.

[0025] By adopting the above technical solution, a preferable dispersion temperature can promote the uniform dispersion of each raw material and improve the uniformity of the protective film. Dividing the drying process into two stages and respectively controlling the preferable segmented drying temperature can avoid the deformation or performance deterioration of the protective film due to too high temperature during drying, and at the same time ensure the full volatilization of the solvent in the system, improve the denseness and mechanical strength of the protective film, thereby improving the optical performance, light and heat stability and antistatic performance of the protective film.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. The protective film for a semiconductor lithography mask plate of the present application is synergistically combined with a perfluoroethylene-propylene copolymer dispersion and a polytetrafluoroethylene dispersion, and the heat-resistant agent and the antistatic agent have a good synergistic effect. The antistatic agent is stably dispersed in the system of the heat-resistant agent, the perfluoroethylene-propylene copolymer dispersion and the polytetrafluoroethylene dispersion, so that the protective film has good light and heat stability while having good antistatic performance, avoiding the problem of damage to the lithography pattern caused by electrostatic discharge or ultraviolet light irradiation thermal reaction, being applicable to the protection of lithography mask plates, and at the same time the moderate light transmittance performance can also improve the accuracy of the lithography pattern.

[0027] 2. The heat-resistant agent is prepared by reacting perfluorooctylethyl acrylate with alkenyl phenyl glycidyl ether through a solvent and a catalyst. By introducing phenyl and ether groups into perfluorooctylethyl acrylate, the prepared heat-resistant agent can be intertwined and dispersed with the perfluoroethylene-propylene copolymer dispersion and the polytetrafluoroethylene dispersion. The molecular chain segments can fully stretch and form a certain steric hindrance, which is beneficial to the uniform dispersion of the antistatic agent in the system, improving the light and heat resistance and flexibility of the prepared protective film while enhancing the antistatic property of the protective film, and preventing the migration of the antistatic agent during the thermal reaction, resulting in a reduction in the antistatic property of the protective film.

[0028] 3. The antistatic agent is compounded by dimethyldiallylammonium chloride-acrylamide copolymer and 1-ethyl-3-methylimidazolium ethyl sulfate in a specific ratio, and can be uniformly dispersed in the system composed of the heat-resistant agent, the perfluoroethylene-propylene copolymer dispersion and the polytetrafluoroethylene dispersion, without easily occurring problems of diffusion and migration, and having good light and heat stability and antistatic performance.

[0029] 4. In the preparation method, through a staged drying process, the solvent is initially removed at a lower temperature and then cured at a higher temperature to ensure that all raw materials are fully dispersed and form a uniform and stable film layer structure, further improving the comprehensive performance of the protective film. Specific Embodiments

[0030] The following further elaborates on the present application in conjunction with embodiments.

[0031] The following are the sources and specifications of some raw materials of the present application. The raw materials used in the preparation examples and embodiments of the present application can all be obtained commercially, including but not limited to the raw materials of the following models and manufacturers, and raw materials with the same performance can all be used: 1. Perfluoroethylene-propylene copolymer dispersion: Model DS603A, solid content 55wt%; 2. Polytetrafluoroethylene dispersion: Model D2510F, solid content 60wt%; 3. Perfluorooctylethyl acrylate: CAS No. 27905-45-9, content 99%; 4. Dimethyldiallylammonium Chloride - Acrylamide Copolymer: Model M550; 5. 1 - Ethyl - 3 - methylimidazolium Ethyl Sulfate: CAS No. 342573 - 75 - 5, Content 99%.

[0032] Preparation Example of Heat - resistant Agent Preparation Example 1 Preparation Example 1 discloses a heat - resistant agent, which is prepared by the following steps: Add 2 kg of perfluorooctylethyl acrylate and 0.9 kg of alkenylphenyl glycidyl ether to 3.5 kg of N,N - dimethylformamide. After dispersion, add 0.005 kg of benzoyl peroxide as a catalyst, heat up to 70 °C, react for 3 h, and remove the solvent after the reaction to obtain the heat - resistant agent.

[0033] Preparation Examples 2 - 3 The differences between Preparation Examples 2 - 3 and Preparation Example 1 are that the raw material dosages and preparation conditions are different. For details, see Table 1 below.

[0034] Table 1 Parameter Table of Preparation Examples 1 - 3 Preparation Comparative Example 1 The difference between Preparation Comparative Example 1 and Preparation Example 1 is that 4 - vinylphenyl glycidyl ether is replaced with allyl glycidyl ether in equal amounts, and the others are the same as Preparation Example 1.

[0035] Preparation Comparative Example 2 The difference between Preparation Comparative Example 2 and Preparation Example 1 is that perfluorooctylethyl acrylate is replaced with trifluoroethyl methacrylate in equal amounts, and the others are the same as Preparation Example 1. Examples

[0036] Example 1 Example 1 discloses a preparation method of a protective film for a semiconductor lithography mask plate, which is prepared by the following steps: S1. Add 2 kg of perfluoroethylene - propylene copolymer dispersion, 2.8 kg of polytetrafluoroethylene dispersion, 1.2 kg of the heat - resistant agent prepared in Preparation Example 1, 0.45 kg of an antistatic agent (composed of a dimethyldiallylammonium chloride - acrylamide copolymer and dodecyl dimethyl benzyl ammonium chloride with a weight ratio of 1:2), and 0.1 kg of an antioxidant (composed of antioxidant 1010 and antioxidant 168 with a weight ratio of 1:1) to a mixer, and disperse evenly under the condition of a temperature of 45 °C to obtain a dispersion; S2. Cast the dispersion into a film, and then dry it in stages. Control the drying temperature in the first stage to be 90 °C and dry for 10 min, and the drying temperature in the second stage to be 140 °C and dry for 10 min to obtain a protective film for a semiconductor lithography mask plate with a thickness of 10 μm.

[0037] Example 2-3 The difference between Example 2-3 and Example 1 lies in the different amounts of raw materials used and preparation conditions. See Table 2 below for details.

[0038] Table 2 Parameter Table of Examples 1-3 Example 4 The difference between Example 4 and Example 1 is that the antistatic agent consists of a dimethyldiallylammonium chloride-acrylamide copolymer and 1-ethyl-3-methylimidazolium ethyl sulfate with a weight ratio of 1:2, and the others are the same as Example 1.

[0039] Example 5 The difference between Example 5 and Example 1 is that the antistatic agent consists of a dimethyldiallylammonium chloride-acrylamide copolymer and 1-ethyl-3-methylimidazolium ethyl sulfate with a weight ratio of 1:3, and the others are the same as Example 1.

[0040] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the heat-resistant agent is sourced from the preparation of Comparative Example 1, and the others are the same as Example 1.

[0041] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the heat-resistant agent is sourced from the preparation of Comparative Example 2, and the others are the same as Example 1.

[0042] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the heat-resistant agent is equally replaced with polytetrafluoroethylene dispersion, and the others are the same as Example 1.

[0043] The difference between Comparative Example 4 and Example 1 is that the perfluoroethylenepropylene copolymer dispersion is equally replaced with polytetrafluoroethylene dispersion, and the others are the same as Example 1.

[0044] Performance Detection Test The following is a performance test on the photomask protective film for semiconductors prepared in Examples 1-5 and Comparative Examples 1-4: 1. Initial Volume Resistivity Test Use a volume resistivity tester to test the initial volume resistivity (unit: Ω·cm) of the protective film, and test and record the test results; 2. Heat-resistant Volume Resistivity Test Place the protective film in an ultraviolet aging test chamber, adjust the ultraviolet wavelength to 340 nm, the humidity to 85%, and the temperature to 65 °C. Place it for 8 h, take it out, dry it, and use a volume resistivity tester to measure the heat-resistant volume resistivity of the protective film (unit: Ω·cm). Test and record the test results; 3. Light transmittance test: Use a light transmittance tester to measure the light transmittance (unit: %) of the protective film. Test and record the test results.

[0045] The following are the performance test data of the photolithography mask protective films for semiconductors prepared in Examples 1-5 and Comparative Examples 1-4. See Table 3 below for details.

[0046] Table 3 Performance test table of Examples 1-5 and Comparative Examples 1-4 Combining Examples 1-3, Examples 4-5, and Comparative Examples 1-3 and referring to Table 3, it can be concluded that by compounding the heat-resistant agent and antistatic agent of the present application, the photolithography light and heat stability of the prepared protective film can be improved, and at the same time, it can also have good light transmittance. Compared with Example 1, Examples 4-5 optimized the proportion of the antistatic agent, resulting in a decrease in the volume resistivity of the prepared protective film and an improvement in the antistatic performance. After the ultraviolet and heat resistance test, the volume resistivity increased slightly, but it still remained within 10 7 range, and its light transmittance also reached 92.3%, indicating that the antistatic agent with better components has good antistatic stability in the protective film system of the present application. In Comparative Examples 1-2, the preparation of the heat-resistant agent was changed. In Comparative Example 3, the heat-resistant agent was directly not added and replaced with polytetrafluoroethylene dispersion liquid. The volume resistivity of the prepared protective film increased, the antistatic performance decreased, and the volume resistivity increased significantly after the ultraviolet and heat resistance test, indicating that the heat-resistant agent of the present application plays a crucial role in the light and heat resistance performance of the protective film.

[0047] Combining Example 1 and Comparative Example 4 and referring to Table 3, it can be concluded that in Comparative Example 4, the polytetrafluoroethylene dispersion liquid was replaced with an equal amount of polytetrafluoroethylene dispersion liquid, resulting in an increase in the initial volume resistivity of the prepared protective film and an increase in the volume resistivity after the light and heat resistance test, indicating that the compounding of the heat-resistant agent, polytetrafluoroethylene propylene dispersion liquid, and polytetrafluoroethylene dispersion liquid in the optimal proportion of the present application can better improve the dispersion uniformity of the antistatic agent and at the same time improve the antistatic performance of the protective film.

[0048] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A photolithography mask protective film for semiconductors, characterized in that: Made from the following raw materials in parts by weight: 20-30 parts of polyperfluoroethylene propylene dispersion 18-28 parts of polytetrafluoroethylene dispersion Heat resistant agent 12-20 parts Antistatic agent 4.5-8.5 parts 1-3 parts of antioxidants; The heat-resistant agent is prepared by reacting perfluorooctyl ethyl acrylate, alkenyl phenyl glycidyl ether, a solvent and a catalyst.

2. The photolithography mask protective film for semiconductor according to claim 1, characterized in that: The heat-resistant agent is prepared from the following raw materials in parts by weight: Perfluorooctyl ethyl acrylate 20-30 parts 6-12 parts of alkenylphenyl glycidyl ether 35-45 parts of solvent Catalyst 0.05-0.15 parts.

3. The photolithography mask protective film for semiconductor according to claim 2, characterized in that: The alkenylphenyl glycidyl ether is 4-vinylphenyl glycidyl ether and / or diisopropenylphenyl glycidyl ether.

4. The photolithography mask protective film for semiconductor according to claim 2, characterized in that: The solvent is any one of N,N-dimethylacetamide, N-methylpyrrolidone and N,N-dimethylformamide; and the catalyst is dibenzoyl peroxide.

5. A photolithography mask protective film for semiconductors according to any one of claims 1 to 4, characterized in that: The heat-resistant agent is prepared by the following steps: Perfluorooctyl ethyl acrylate and alkenylphenyl glycidyl ether are added to a solvent, and after dispersion, a catalyst is added, and the temperature is raised to 70-85° C. and the reaction is carried out for 1-3 hours. After the reaction is completed, the solvent is removed to obtain a heat-resistant agent.

6. The photolithography mask protective film for semiconductor according to claim 1, characterized in that: The antistatic agent is composed of dimethyldiallylammonium chloride-acrylamide copolymer and 1-ethyl-3-methylimidazole ethyl sulfate in a weight ratio of 1:(2-3).

7. The photolithography mask protective film for semiconductor according to claim 1, characterized in that: The antioxidant is antioxidant 1010 and / or antioxidant 168.

8. The photolithography mask protective film for semiconductor according to claim 1, characterized in that: The thickness of the photolithography mask protective film is 5-12 μm.

9. A method for preparing a photolithography mask protective film for semiconductors according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, adding a polyperfluoroethylene propylene dispersion, a polytetrafluoroethylene dispersion, a heat-resistant agent, an antistatic agent and an antioxidant into a mixing device, dispersing them evenly to obtain a dispersion; S2. Casting the dispersion into a film, drying it, and obtaining a photolithography mask protective film for semiconductors.

10. The method for preparing a semiconductor photolithography mask protective film according to claim 9, characterized in that: The dispersion temperature in step S1 is 45-55°C, and the drying temperature in step S2 is divided into two stages, the drying temperature in the first stage is 90-110°C, and the drying temperature in the second stage is 120-140°C.

Images