Poly (p-hydroxystyrene) photoresist film-forming resin and preparation method thereof

Abstract

The invention relates to poly (p-hydroxystyrene) photoresist film-forming resin and a preparation method thereof, relates to the technical field of photoresist materials, and is used for solving at least one of the problems of relatively wide molecular weight distribution, uncontrollable molecular weight and the like of the film-forming resin prepared by the existing method. According to the method disclosed by the invention, free radical polymerization reaction is carried out under photo-initiation through a reversible addition-fragmentation chain transfer polymerization technology, so that the reversible inactivation reaction of free radicals in a polymerization reaction system is controlled, the molecular weight distribution of the synthesized deep ultraviolet photoresist film-forming resin (poly-p-hydroxystyrene photoresist film-forming resin) is narrow, the PDI is less than 1.2, the reaction is instantly controlled, and the film-forming effect is good. The reaction conditions are mild; the energy consumption is low; and the product is easy to separate and purify.

Description

Technical Field

[0001] The invention relates to the technical field of photoresist materials, and in particular to a poly(p-hydroxystyrene) photoresist film-forming resin and a preparation method thereof. Background Art

[0002] Photoresist, also known as photoresist, is a polymer material that is highly sensitive to light and radiation. Under the irradiation or radiation of ultraviolet rays, electron beams, excimer laser beams, ion beams, X-rays, etc., the material can undergo photochemical changes, resulting in changes in the solubility characteristics of its film before and after exposure. Based on this, it can be divided into positive photoresist and negative photoresist. The composition of photoresist usually includes film-forming resin, photosensitizer, inhibitor, solvent and some additives. Among them, film-forming resin is the key component of photoresist, and different types of resins will have different influences and effects on the performance of photoresist.

[0003] Among them, deep ultraviolet photoresist resin is a type of photoresist film-forming resin specially designed for deep ultraviolet lithography. It is usually required that this type of resin has high transparency within the deep ultraviolet wavelength range (usually at 248nm or 193nm) so that light can effectively penetrate and achieve the etching of fine patterns. At the same time, before and after exposure, the solubility can change significantly, so as to facilitate the development process, and can withstand high temperature environments during the photolithography process to maintain structural stability. Poly (p-hydroxystyrene) (poly (p-hydroxystyrene, PHS) type photoresist film-forming resin is a commonly used deep ultraviolet photoresist resin, which is usually prepared by free radical polymerization method, with p-hydroxystyrene as monomer, in a suitable solvent, by adding a free radical initiator (such as AIBN) to carry out solution polymerization or bulk polymerization.

[0004] In order to achieve excellent lithography effects, the molecular weight of PHS resin needs to be precisely controlled to ensure the performance consistency and repeatability of the photoresist during exposure and development. At the same time, the regularity of the molecular structure of the polymer chain segment has a great influence on the performance of the resin. A narrow molecular weight distribution helps to improve the performance uniformity of the photoresist and reduce batch-to-batch differences. This helps to achieve high-resolution patterning and reduce defects. For deep ultraviolet photoresists, PDI is usually required to be less than 1.3, and ideally less than 1.1. However, the molecular weight of PHS synthesized by traditional free radical polymerization technology is uncontrollable, and the molecular weight distribution is wide, making it impossible to finely control the composition and structure of the resin. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a poly(p-hydroxystyrene) photoresist film-forming resin and a preparation method thereof, so as to solve at least one of the problems of the film-forming resin prepared by the existing method, such as wide molecular weight distribution and uncontrollable molecular weight.

[0006] In a first aspect, the present invention provides a method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin, comprising subjecting a polymerization reaction system to a free radical polymerization reaction under light initiation to obtain the film-forming resin;

[0007] Wherein, the polymerization reaction system comprises a photocatalyst, a polymerization monomer, a chain transfer agent and a solvent, and the photocatalyst is polythiol.

[0008] Furthermore, the photoinitiation is a free radical polymerization reaction in the absence of oxygen, ultraviolet light or visible light.

[0009] Furthermore, the wavelength of the ultraviolet light is 260-390 nm, and the wavelength of the visible light is 340-540 nm.

[0010] Furthermore, the polythiol includes one or more of 1,2-ethanedithiol, 1,3-propanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakisthioacetate and pentaerythritol tetrakis-3-mercaptopropionate.

[0011] Furthermore, the polymerization reaction temperature is 25-45°C.

[0012] Furthermore, the polymerizable monomer includes a tert-butyloxycarbonyl-protected p-hydroxystyrene monomer. Preferably, the mass fraction of the tert-butyloxycarbonyl-protected p-hydroxystyrene monomer in the polymerization reaction system is 10 to 60%.

[0013] Furthermore, the polymerizable monomers also include comonomers. Preferably, the comonomers include one or more of methyl acrylate, ethyl acrylate, tert-butyl acrylate and tert-butyl methacrylate.

[0014] Furthermore, the molar ratio of the comonomer to the tert-butyloxycarbonyl-protected p-hydroxystyrene monomer is 0.05 to 1:1;

[0015] and or, the molar ratio of the polymerization monomer to the chain transfer agent is 100 to 1200:1;

[0016] And / or, the solvent is one or more of tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

[0017] Furthermore, the method further comprises, after the polymerization reaction is completed, adding the polymerization solution into a poor solvent for precipitation treatment, filtering, and drying to obtain the film-forming resin.

[0018] In a second aspect, the present invention provides a poly(p-hydroxystyrene) photoresist film-forming resin prepared by the above method, wherein the PDI of the film-forming resin is less than 1.2 and the number average molecular weight is 2000-100000.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] (1) The method of the present invention uses reversible addition-fragmentation chain transfer (RAFT) polymerization technology to carry out free radical polymerization under light initiation, so that the reversible deactivation reaction of free radicals in the polymerization reaction system is controlled, the molecular weight distribution of the synthesized deep ultraviolet photoresist film-forming resin (poly(p-hydroxystyrene) photoresist film-forming resin) is narrow, PDI < 1.2, the reaction is immediately controlled, the response rate is fast, the reaction conditions are mild, the energy consumption is low, and the product is easy to separate and purify;

[0021] (2) When the polythiol described in the present invention is used as a photocatalyst, based on the unique photochemical properties of this type of compound, free radicals can be formed under irradiation of visible light or ultraviolet light of a specific wavelength to provide electrons, thereby regulating the reversible deactivation balance of free radicals in the RAFT system, thereby achieving efficient polymerization of p-hydroxystyrene and its comonomers;

[0022] (3) The polymerization reaction conditions of the present invention are mild, and the reaction temperature is lower than that of the traditional RAFT polymerization reaction (usually not less than 65° C.). In particular, the use of visible light as the light source can reduce the cost of the reactor, and there is no need to use high-transmittance quartz glass as the material of the reactor body. At the same time, the background absorption and the loss in the transmission path are greatly reduced, thereby improving the photon utilization efficiency.

[0023] (4) The photopolymerization reaction system of the present invention is simple and does not require the introduction of metal ions. After the reaction is completed, the product is separated by precipitation and filtration, which is easy to scale up. The protecting group can be removed by heating for a short time, and the operation is convenient.

[0024] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0026] Figure 1 This is a molecular weight distribution diagram of the poly(p-hydroxystyrene) product without removing the BOC protecting group measured by gel permeation chromatography (GPC) in Example 1;

[0027] Figure 2 This is the molecular weight distribution diagram of the poly(p-hydroxystyrene) product after removal of the BOC protecting group measured by GPC in Example 1. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0029] A specific embodiment of the present invention discloses a method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin, comprising subjecting a polymerization reaction system to a free radical polymerization reaction under light initiation to obtain the film-forming resin;

[0030] Wherein, the polymerization reaction system comprises a photocatalyst, a polymerization monomer, a chain transfer agent and a solvent, and the photocatalyst is polythiol.

[0031] The method of the invention uses reversible addition-fragmentation chain transfer (RAFT) polymerization technology to carry out free radical polymerization reaction under light initiation, so that the reversible deactivation reaction of free radicals in the polymerization reaction system is controlled, the molecular weight distribution of the synthesized deep ultraviolet photoresist film-forming resin (poly(p-hydroxystyrene) photoresist film-forming resin) is narrow, PDI is less than 1.2, the reaction is instantly controlled, the response rate is fast, the reaction conditions are mild, the energy consumption is low, and the product is easy to separate and purify.

[0032] It should be noted that the method of the present invention can control the growth process of the polymerization chain by controlling the on and off of the light source.

[0033] In a specific embodiment, the photoinitiation is a free radical polymerization reaction in the absence of oxygen, ultraviolet light or visible light.

[0034] Specifically, the light power density is 1 to 20 mW / cm 2 , for example, 1mW / cm 2 、3mW / cm 2 , 5mW / cm 2 , 7mW / cm 2 , 9mW / cm 2 、11mW / cm 2 、13mW / cm 2 、15mW / cm 2、17mW / cm 2 、19mW / cm 2 , 20mW / cm 2 The illumination time is 5 to 48 hours, for example, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, and 48 hours.

[0035] It should be noted that if the illumination power density is too low, the reaction cannot be initiated or the reaction efficiency is low; if it is too high, the molecular weight distribution becomes wider; if the illumination time is too short, the degree of polymerization is not reached; if the time is too long, energy consumption increases.

[0036] Specifically, the wavelength of the ultraviolet light is 260-390nm, for example, 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, and the wavelength of the visible light is 340-540nm, for example, 340nm, 360nm, 380nm, 400nm, 420nm, 440nm, 460nm, 480nm, 500nm, 520nm, 540nm.

[0037] The present invention has been found through a large number of tests that when the wavelength is within the above range, the reaction material of the present invention proceeds and the initiation efficiency is relatively high.

[0038] In a specific embodiment, the polythiol includes one or more of 1,2-ethanedithiol, 1,3-propanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakisthioacetate and pentaerythritol tetrakis-3-mercaptopropionate.

[0039] Preferably, the concentration of the polythiol in the polymerization reaction system is 0.2-10 μL / mL, for example, 0.2 μL / mL, 0.5 μL / mL, 1.0 μL / mL, 1.5 μL / mL, 2.0 μL / mL, 2.5 μL / mL, 3.0 μL / mL, 3.5 μL / mL, 4.0 μL / mL, 4.5 μL / mL, 5.0 μL / mL, 5.5 μL / mL, 6.0 μL / mL, 6.5 μL / mL, 7.0 μL / mL, 7.5 μL / mL, 8.0 μL / mL, 8.5 μL / mL, 9.0 μL / mL, 9.5 μL / mL, 10 μL / mL.

[0040] It should be noted that after a large number of experiments, it was found that when the above-mentioned polythiol is used as a photocatalyst, based on the unique photochemical properties of this type of compound, free radicals can be formed under irradiation of visible light or ultraviolet light of a specific wavelength to provide electrons, thereby regulating the reversible deactivation balance of free radicals in the RAFT system, thereby achieving efficient polymerization of hydroxystyrene and its copolymers.

[0041] In a specific embodiment, the polymerization reaction temperature is 25-45°C.

[0042] The polymerization reaction conditions of the present invention are mild, and the reaction temperature is lower than that of the traditional RAFT polymerization reaction (usually not less than 65°C). In particular, the use of visible light as a light source can reduce the cost of the reactor, and there is no need to use high-transmittance quartz glass as the material of the reactor body. At the same time, the background absorption and the loss in the transmission path are greatly reduced, and the photon utilization efficiency is improved.

[0043] In a specific embodiment, the polymerizable monomer includes a tert-butyloxycarbonyl-protected p-hydroxystyrene monomer.

[0044] Preferably, the tert-butoxycarbonyl-protected p-hydroxystyrene monomer is 4-(tert-butoxycarbonyloxy)styrene.

[0045] The present invention can avoid the influence of phenolic hydroxyl group on polymerization reaction by protecting tert-butyloxycarbonyl group.

[0046] In a specific embodiment, the mass fraction of the tert-butyloxycarbonyl protected p-hydroxystyrene monomer in the polymerization reaction system is 10-60%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%. If the mass fraction is low, polymerization is not easy to occur, and if the mass fraction is too high, the system viscosity is too high, which affects the polymerization reaction.

[0047] Preferably, the polymerizable monomer further comprises a comonomer.

[0048] In a specific embodiment, the comonomer includes one or more of methyl acrylate, ethyl acrylate, tert-butyl acrylate and tert-butyl methacrylate.

[0049] Preferably, the molar ratio of the comonomer to the tert-butyloxycarbonyl-protected p-hydroxystyrene monomer is 0.05 to 1:1, for example, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1.

[0050] It should be noted that the tert-butyloxycarbonyl-protected p-hydroxystyrene monomer and comonomer are filtered with neutral alumina particles before use to remove the polymerization inhibitor in the monomer.

[0051] In a specific embodiment, the chain transfer agent includes one or more of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid and methyl(phenyl)aminodithiocarboxylic acid cyanomethyl ester.

[0052] Preferably, the molar ratio of the polymerizable monomer to the chain transfer agent is 100 to 1200:1, for example, 100:1, 200:1, 300:1, 400:1, 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, 1200:1, and the molecular weight is controlled by controlling the ratio of the polymerizable monomer to the chain transfer agent.

[0053] It should be noted that in the light-controlled RAFT polymerization reaction system of the present invention, the molecular weight and molecular weight distribution of the poly(p-hydroxystyrene) and its copolymers are controlled by light intensity, light exposure time, monomer concentration, and the amount of catalyst and chain transfer agent used, and the controllability is relatively strong.

[0054] In a specific embodiment, the solvent is one or more of tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

[0055] In a specific embodiment, the method further comprises, after the polymerization reaction is completed, adding the polymerization solution into a poor solvent for precipitation treatment, filtering, and drying to obtain the film-forming resin.

[0056] Specifically, the poor solvent is one or more of ether, petroleum ether, n-hexane, n-pentane, n-heptane, methanol, ethanol, water and isopropanol.

[0057] Specifically, the drying temperature is 60° C., and the drying time is greater than 6 hours, such as 6-8 hours.

[0058] Preferably, the film-forming resin is subjected to a heat treatment to obtain a film-forming resin with some protecting groups removed.

[0059] Preferably, the heating temperature is 130-220°C, for example, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, and the heating time is 5-30min, for example, 5min, 7min, 9min, 11min, 13min, 15min, 17min, 19min, 21min, 23min, 25min, 27min, 29min, 30min.

[0060] By controlling the heating temperature and heating time, some protective groups can be removed to obtain resins with different structures, matching different photoresist lithography processes. The removal of some protective groups can be determined by weight loss test, and the molecular weight of the film-forming resin with some protective groups removed can be obtained by existing calculation methods through nuclear magnetic resonance or weight ratio of the removed groups.

[0061] It should be noted that the photoinitiated polymerization reaction system of the present invention is simple, does not require the introduction of metal ions, and the product separation after the reaction is completed is carried out by precipitation and filtration, which is easy to scale up. The protecting group can be removed by heating for a short time, and the operation is convenient. The monomer conversion rate of the method of the present invention is 50-90%.

[0062] Another specific embodiment of the present invention discloses a poly(p-hydroxystyrene) photoresist film-forming resin prepared by the above method, wherein the PDI of the film-forming resin is less than 1.2, preferably, the PDI is less than 1.1, and the number average molecular weight is 2000-100000.

[0063] The technical scheme of the present invention is further explained below in conjunction with specific examples. In the following examples, the p-hydroxystyrene protected by tert-butyloxycarbonyl group is selected as 4-(tert-butyloxycarbonyloxy)styrene.

[0064] Example 1

[0065] The preparation method of a poly(p-hydroxystyrene) photoresist film-forming resin of the present embodiment specifically comprises the following steps:

[0066] First, the tert-butyloxycarbonyl-protected p-hydroxystyrene was filtered with neutral alumina particles, and then 1.186 g of tert-butyloxycarbonyl-protected p-hydroxystyrene monomer and 4.21 mL of tetrahydrofuran solvent were added to a 10 mL glass reaction tube, followed by 6.8 μL of trimethylolpropane tris(3-mercaptopropionate) and 12.4 μL of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, which was sealed with a rubber stopper and passed nitrogen for 10 min to remove oxygen in the solvent system. At an illumination power density of 4 mW / cm 2 The reaction was carried out under irradiation with blue visible light of wavelength 450nm for 48h and the reaction temperature was 30℃.

[0067] After the reaction is completed, the polymer solution is added dropwise to 50 mL of petroleum ether to precipitate the polymer, and the polymer solid is separated by filtration. The obtained solid is dissolved in tetrahydrofuran again and precipitated in petroleum ether, and after repeated three times, it is placed in a vacuum oven at 60°C and dried for 8 hours. The dried polymer solid product is dissolved in N,N-dimethylacetamide, and the molecular weight and molecular weight distribution parameters are tested by gel permeation chromatography. The test results are shown in Figure 1 , and are summarized in Table 1 together with the experimental conditions. Among them, M in the horizontal and vertical axes is the number average molecular weight (i.e., Mn,GPC in Table 1), and the vertical axis is the normalized mass fraction of polymers with different molecular weights. From the test results, it can be seen that the molecular weight distribution of the polymer product obtained in the above visible light controlled polymerization system is very narrow.

[0068] The polymer product was dried in an oven at 200°C for 5 minutes and then taken out. The molecular weight and molecular weight distribution were further tested using a gel permeation chromatography analyzer. The test results are shown in Figure 2 The results showed that the poly(p-hydroxystyrene) removed some tert-butyloxycarbonyl groups, with a weight loss rate of about 46%.

[0069] Example 2

[0070] The preparation method of a poly(p-hydroxystyrene) photoresist film-forming resin of the present embodiment specifically comprises the following steps:

[0071] tert-Butoxycarbonyl-protected p-hydroxystyrene and tert-butyl acrylate were filtered with neutral alumina particles. 0.874 g of tert-Butoxycarbonyl-protected p-hydroxystyrene, 0.373 g of tert-butyl acrylate and 3.5 mL of N,N-dimethylformamide were added to a 10 mL glass reaction tube. Then 8.3 μL of 1,3-propanedithiol and 14.7 μL of 4-cyano-4-[(dodecylsulfanylsulfanyl)sulfanyl]pentanoic acid were added. The tube was sealed with a rubber stopper and nitrogen was passed through for 10 min to remove excess oxygen in the system. The reaction mixture was stirred at a light power density of 6 mW / cm 2 , under ultraviolet light with a wavelength of 380nm, the reaction was carried out for 24h at a reaction temperature of 35℃.

[0072] After the reaction is completed, the polymer solution is added dropwise to 70 mL of deionized water to precipitate the polymer, and the polymer solid is separated by filtration. The obtained solid is dissolved in N, N-dimethylformamide again and precipitated in deionized water. After repeated three times, it is placed in a vacuum oven at 60°C for drying. The drying time is 8 hours. The dried polymer solid product is dissolved in N, N-dimethylacetamide, and the molecular weight and molecular weight distribution parameters are tested by gel permeation chromatography. The test results are summarized in Table 1. The dried polymer product is placed in an oven at 210°C and dried for 10 minutes and then taken out. The poly(p-hydroxystyrene) removes the tert-butyloxycarbonyl group, and the weight loss rate is about 40%.

[0073] Example 3

[0074] The preparation method of a poly(p-hydroxystyrene) photoresist film-forming resin of the present embodiment specifically comprises the following steps:

[0075] tert-Butyloxycarbonyl protected p-hydroxystyrene and methyl acrylate were filtered with neutral alumina particles. 1.641 g of tert-Butyloxycarbonyl protected p-hydroxystyrene, 0.583 g of methyl acrylate and 3.0 mL of toluene were added to a 10 mL glass reaction tube. Then 4.6 μL of pentaerythritol tetrathioglycolate and 18.3 μL of methyl (phenyl) amino dithiocarboxylic acid cyanomethyl ester were added. The tube was sealed with a rubber stopper and nitrogen was passed through for 10 min to remove excess oxygen in the system. The reaction was carried out at an illumination power density of 4 mW / cm 2 , under irradiation of blue visible light with a wavelength of 450nm, the reaction was carried out for 48h at a reaction temperature of 30℃.

[0076] After the reaction is completed, the polymer solution is added dropwise to 50 mL of methanol to precipitate the polymer, and the polymer solid is separated by filtration. The obtained solid is dissolved in toluene again and precipitated in methanol, and after repeated three times, it is placed in a vacuum oven at 60°C for 8 hours. The dried polymer solid product is dissolved in N,N-dimethylacetamide, and the molecular weight and molecular weight distribution parameters are tested by gel permeation chromatography. The test results are summarized in Table 1. The dried polymer product is placed in an oven at 180°C and dried for 4 minutes and then taken out. The poly(p-hydroxystyrene) removes part of the tert-butyloxycarbonyl group, and the weight loss rate is about 37%.

[0077] Example 4

[0078] The preparation method of a poly(p-hydroxystyrene) photoresist film-forming resin of the present embodiment specifically comprises the following steps:

[0079] The tert-butyloxycarbonyl-protected p-hydroxystyrene was filtered with neutral alumina particles. 2.641 g of tert-butyloxycarbonyl-protected p-hydroxystyrene and 2.4 mL of N,N-dimethylacetamide were added to a 10 mL glass reaction tube. Then, 5.2 μL of pentaerythritol tetra-3-mercaptopropionate and 24.8 μL of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid were added. The tube was sealed with a rubber stopper and nitrogen was passed through for 10 min to remove excess oxygen in the system. The reaction mixture was stirred at a light power density of 4 mW / cm 2 , under irradiation with blue visible light of wavelength 430nm, the reaction was carried out for 48h at a reaction temperature of 30℃.

[0080] After the reaction is completed, the polymer solution is added dropwise to 50 mL of deionized water to precipitate the polymer, and the polymer solid is separated by filtration. The obtained solid is dissolved in N, N-dimethylacetamide again and precipitated in deionized water. After repeated three times, it is placed in a vacuum oven at 60°C for drying for 6 hours. The dried polymer solid product is dissolved in N, N-dimethylacetamide, and the molecular weight and molecular weight distribution parameters are tested by gel permeation chromatography. The test results are summarized in Table 1. The dried polymer product is placed in an oven at 210°C and dried for 10 minutes and then taken out. The poly(p-hydroxystyrene) removes part of the tert-butyloxycarbonyl group, and the weight loss rate is about 48%.

[0081] Comparative Example 1

[0082] The preparation method of the poly(p-hydroxystyrene) photoresist film-forming resin in this comparative example is the same as that in Example 1, except that there is no light polymerization.

[0083] The experimental results show that when there is no light, the reaction cannot proceed normally and no polymerization product is generated. The results are shown in Table 1.

[0084] Comparative Example 2

[0085] The preparation method of the poly(p-hydroxystyrene) photoresist film-forming resin of this comparative example is the same as that of Example 1, except that trimethylolpropane tris(3-mercaptopropionate) is replaced by a monothiol compound dodecyl mercaptan as a photocatalyst.

[0086] The experimental results show that the monothiol compound as a photocatalyst has low initiation efficiency and monomer conversion rate, the molecular weight of the polymerized product is smaller than that of Example 1, the molecular weight distribution becomes wider, and the reaction controllability is poor. The results are shown in Table 1. It shows that only by using the photocatalyst of the present invention can a film-forming resin with a narrow molecular weight distribution be prepared.

[0087] Comparative Example 3

[0088] The preparation method of the poly(p-hydroxystyrene) photoresist film-forming resin of this comparative example is the same as that of Example 1, except that the light source is replaced from blue visible light to red visible light with a wavelength of 620 nm.

[0089] The experimental results show that the photon energy of red visible light is relatively low and cannot effectively initiate the polymerization reaction, and no polymerization product is generated in the system. The results are shown in Table 1. This shows that the polymerization reaction can only be carried out under the illumination conditions of the present invention.

[0090] Table 1 Results of photo-controlled free radical polymerization of poly(p-hydroxystyrene)

[0091] Group Wavelength / nm <![CDATA[Illumination intensity / mW·cm -2 > Time / h <![CDATA[M n,GPC ]]> PDI Example 1 450 4 48 26,630 1.07 Example 2 380 6 24 29,510 1.09 Example 3 450 4 48 31,240 1.05 Example 4 430 4 48 33,580 1.07 Comparative Example 1 — 0 24 — — Comparative Example 2 450 4 48 12,410 1.52 Comparative Example 3 620 4 48 — —

[0092] Test Example 1

[0093] In this test example, only the polymerization temperature was changed. Other methods were the same as those in Example 1. The poly(p-hydroxystyrene) photoresist film-forming resin was used to investigate the effect of temperature on the molecular weight distribution. The results are shown in Table 2.

[0094] Table 2

[0095]

[0096]

[0097] It can be seen from the above table that when the polymerization temperature is between 25 and 45°C, the molecular weight and PDI of the prepared film-forming resin are both excellent, PDI < 1.2, and when the temperature is ≥ 50°C, PDI > 1.2.

[0098] The above test was also conducted on other embodiments, and the results were basically the same. Due to limited space, they are not listed one by one.

[0099] Test Example 2

[0100] In this test example, only the light power density was changed. Other methods were the same as those in Example 1. The poly(p-hydroxystyrene) photoresist film-forming resin was used to investigate the effect of temperature on the molecular weight distribution. The results are shown in Table 3.

[0101] Table 3

[0102]

[0103] It can be seen from the table above that when the light density is between 1 and 20 mW / cm 2 When the light density is too high or too low, the PDI is large. When the light density is too low, the molecular weight decreases.

[0104] The above tests were also conducted on other embodiments, and the results were basically the same. Due to limited space, they are not listed one by one.

[0105] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin, characterized in that: The method comprises subjecting the polymerization reaction system to a free radical polymerization reaction under light initiation to obtain the film-forming resin; Wherein, the polymerization reaction system comprises a photocatalyst, a polymerization monomer, a chain transfer agent and a solvent, and the photocatalyst is polythiol.

2. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 1, characterized in that: The photoinitiation is a free radical polymerization reaction in the absence of oxygen, ultraviolet light or visible light.

3. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 2, characterized in that: The wavelength of the ultraviolet light is 260-390 nm, and the wavelength of the visible light is 340-540 nm.

4. A method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to any one of claims 1 to 3, characterized in that: The polythiol includes one or more of 1,2-ethanedithiol, 1,3-propanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrathioglycolate and pentaerythritol tetra-3-mercaptopropionate.

5. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to any one of claims 1 to 3, characterized in that: The polymerization reaction temperature is 25-45°C.

6. A method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to any one of claims 1 to 3, characterized in that: The polymerizable monomers include tert-butyloxycarbonyl-protected p-hydroxystyrene monomers. Preferably, the mass fraction of the tert-butyloxycarbonyl-protected p-hydroxystyrene monomers in the polymerization reaction system is 10-60%.

7. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 6, characterized in that: The polymerizable monomers also include comonomers. Preferably, the comonomers include one or more of methyl acrylate, ethyl acrylate, tert-butyl acrylate and tert-butyl methacrylate.

8. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 7, characterized in that: The molar ratio of the comonomer to the tert-butyloxycarbonyl protected p-hydroxystyrene monomer is 0.05 to 1:1; and or, the molar ratio of the polymerization monomer to the chain transfer agent is 100 to 1200:1; And / or, the solvent is one or more of tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

9. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 1, characterized in that: The method further comprises adding the polymer solution into a poor solvent for precipitation treatment after the polymerization reaction is completed, filtering, and drying to obtain the film-forming resin.

10. A poly(p-hydroxystyrene) photoresist film-forming resin prepared by the method of any one of claims 1 to 9, characterized in that: The PDI of the film-forming resin is less than 1.2.

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