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

Abstract

The present invention relates to a poly(p-hydroxystyrene) photoresist film-forming resin and a preparation method thereof, and relates to the technical field of photoresist materials. The invention is used to solve at least one of the problems of a wide molecular weight distribution and uncontrollable molecular weight of the film-forming resin prepared by existing methods. The method of the present invention uses reversible addition-fragmentation chain transfer polymerization technology to carry out a free radical polymerization reaction under light initiation, thereby controlling the reversible deactivation reaction of free radicals in the polymerization reaction system. The synthesized deep ultraviolet photoresist film-forming resin (poly(p-hydroxystyrene) photoresist film-forming resin) has a narrow molecular weight distribution, a PDI of less than 1.2, instant reaction control, a fast response rate, mild reaction conditions, low energy consumption, and easy separation and purification of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of photoresist materials, 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. When exposed to ultraviolet light, electron beams, excimer laser beams, ion beams, X-rays, or other radiation, the material undergoes photochemical changes, resulting in shifts in the solubility properties of the film before and after exposure. Based on this, photoresists can be categorized as positive-working and negative-working. Photoresists typically consist of a film-forming resin, a photosensitizer, inhibitors, a solvent, and additives. The film-forming resin is a key component of photoresist, and different resin types can have varying effects on the performance of the photoresist.

[0003] Among them, deep ultraviolet photoresist resin is a type of photoresist film-forming resin designed specifically for deep ultraviolet lithography technology. 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 etching of fine patterns. At the same time, the solubility can change significantly before and after exposure 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, using p-hydroxystyrene as monomer, in an appropriate solvent, by adding a free radical initiator (such as AIBN) to carry out solution polymerization or bulk polymerization.

[0004] In order to achieve excellent photolithography 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 segments 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 usually needs to be less than 1.3, and ideally should be 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 a 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 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 to 390 nm, and the wavelength of the visible light is 340 to 540 nm.

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

[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 traditional RAFT polymerization (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 eliminate the need to use high-transmittance quartz glass as the material of the reactor body. At the same time, background absorption and loss in the transmission path are greatly reduced, thereby improving 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 be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying 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 parts throughout the drawings.

[0026] Figure 1 : is the molecular weight distribution diagram of the poly(p-hydroxystyrene) product without removal of 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 with reference to 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 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 present invention uses reversible addition-fragmentation chain transfer (RAFT) polymerization technology to carry out a free radical polymerization reaction under light initiation, so that the reversible deactivation reaction of free radicals in the polymerization reaction system is controlled. The synthesized deep ultraviolet photoresist film-forming resin (poly(p-hydroxystyrene) photoresist film-forming resin) has a narrow molecular weight distribution, PDI < 1.2, instant reaction control, fast response rate, mild reaction conditions, low energy consumption, and easy separation and purification of the product.

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

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

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

[0039] Preferably, the concentration of the polythiol in the polymerization reaction system is 0.2 to 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, and 10 μL / mL.

[0040] It should be noted that after a large number of experiments, it was found that when the above-mentioned polythiols are used as photocatalysts, 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 and then provide electrons, thereby regulating the reversible deactivation balance of free radicals in the RAFT system, thereby achieving efficient polymerization of hydroxystyrene and its comonomers.

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

[0042] The polymerization reaction conditions of the present invention are mild, with a reaction temperature lower than that of traditional RAFT polymerization (typically no less than 65°C). In particular, the use of visible light as a light source can reduce reactor costs, eliminating the need for high-transmittance quartz glass as the reactor body material. It also significantly reduces background absorption and transmission path losses, thereby improving photon utilization efficiency.

[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 the tert-butyloxycarbonyl group.

[0046] In one 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%, or 60%. If the mass fraction is too low, polymerization is unlikely to occur. If the mass fraction is too high, the system viscosity is too high, affecting the polymerization reaction.

[0047] Preferably, the polymerizable monomer further includes 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. The molecular weight can be 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, illumination time, monomer concentration, and the amount of catalyst and chain transfer agent used, which has high controllability.

[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 polymer 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, for example, 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 5-30 min, for example, 5 min, 7 min, 9 min, 11 min, 13 min, 15 min, 17 min, 19 min, 21 min, 23 min, 25 min, 27 min, 29 min, 30 min.

[0060] By controlling the heating temperature and duration described above, some protecting groups can be removed to obtain resins with different structures, compatible with different photoresist lithography processes. Weight loss testing can confirm the removal of some protecting groups. The molecular weight of the film-forming resin after partial removal of protecting groups can be calculated using existing methods, such as nuclear magnetic resonance (NMR) or the specific gravity of the removed weight.

[0061] It should be noted that the photoinitiated polymerization 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. 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 film-forming resin has a PDI of less than 1.2, preferably less than 1.1, and a number average molecular weight of 2,000-100,000.

[0063] The technical solution of the present invention is further explained below with reference to specific examples. In the following examples, the tert-butyloxycarbonyl-protected p-hydroxystyrene is all 4-(tert-butyloxycarbonyloxy)styrene.

[0064] Example 1

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

[0066] First, the tert-butyloxycarbonyl-protected p-hydroxystyrene was filtered through neutral alumina particles. Then, 1.186 g of the tert-butyloxycarbonyl-protected p-hydroxystyrene monomer and 4.21 mL of tetrahydrofuran solvent were added to a 10 mL glass reaction tube. 6.8 μL of trimethylolpropane tris(3-mercaptopropionate) and 12.4 μL of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid were added. The tube was sealed with a rubber stopper and nitrogen was passed through for 10 minutes to remove oxygen from 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 450 nm for 48 h at a reaction temperature of 30°C.

[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, repeated three times, and then placed in a vacuum oven to dry 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 shown in the figure. Figure 1 , and are summarized in Table 1 along with the experimental conditions. M represents the number-average molecular weight (i.e., Mn,GPC in Table 1) on the horizontal and vertical axes, and the vertical axis represents the normalized mass fraction of polymers of varying molecular weights. The test results demonstrate that the polymer products obtained in this visible light-controlled polymerization system exhibit a very narrow molecular weight distribution.

[0068] The dried polymer product was placed 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 tert-butyloxycarbonyl groups of poly(p-hydroxystyrene) were partially removed, and the weight loss rate was about 46%.

[0069] Example 2

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

[0071] The tert-butyloxycarbonyl-protected p-hydroxystyrene and tert-butyl acrylate were filtered with neutral alumina particles. 0.874 g of tert-butyloxycarbonyl-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. 8.3 μL of 1,3-propanedithiol and 14.7 μL of 4-cyano-4-[(dodecylsulfanylsulfanyl)sulfanyl]pentanoic acid were then 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 under 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, the polymer solution was added dropwise to 70 mL of deionized water to precipitate the polymer, which was then separated by filtration to obtain a polymer solid. The resulting solid was redissolved in N,N-dimethylformamide and precipitated in deionized water three times, and then dried in a vacuum oven at 60°C. The drying time was 8 hours. The dried polymer solid product was dissolved in N,N-dimethylacetamide and tested for parameters such as molecular weight and molecular weight distribution using a gel permeation chromatography analyzer. The test results are summarized in Table 1. The dried polymer product was placed in a 210°C oven and dried for 10 minutes before removal. The tert-butyloxycarbonyl group of poly(p-hydroxystyrene) was removed, and the weight loss rate was approximately 40%.

[0073] Example 3

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

[0075] tert-Butoxycarbonyl-protected p-hydroxystyrene and methyl acrylate were filtered with neutral alumina particles. 1.641 g of tert-Butoxycarbonyl-protected p-hydroxystyrene, 0.583 g of methyl acrylate and 3.0 mL of toluene were added to a 10 mL glass reaction tube. 4.6 μL of pentaerythritol tetrathioglycolate and 18.3 μL of methyl (phenyl) aminodithiocarbamate cyanomethyl ester were then 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 under a light 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, the polymer solution was added dropwise to 50 mL of methanol to precipitate the polymer, which was then separated by filtration to obtain a polymer solid. The resulting solid was redissolved in toluene and precipitated in methanol three times, and then dried in a vacuum oven at 60°C for 8 hours. The dried polymer solid product was dissolved in N,N-dimethylacetamide and tested for parameters such as molecular weight and molecular weight distribution using gel permeation chromatography. The test results are summarized in Table 1. The dried polymer product was placed in an oven at 180°C and dried for 4 minutes before removal. The poly(p-hydroxystyrene) had partially lost its tert-butyloxycarbonyl group, resulting in a weight loss of approximately 37%.

[0077] Example 4

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

[0079] The tert-butyloxycarbonyl-protected p-hydroxystyrene was filtered through 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. 5.2 μL of pentaerythritol tetrakis-3-mercaptopropionate and 24.8 μL of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid were then 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 under a light power density of 4 mW / cm 2 , under irradiation of blue visible light with a wavelength of 430nm, the reaction was carried out for 48h at a reaction temperature of 30℃.

[0080] After the reaction, the polymer solution was added dropwise to 50 mL of deionized water to precipitate the polymer, which was then separated by filtration to obtain a polymer solid. The resulting solid was redissolved in N,N-dimethylacetamide and precipitated in deionized water three times before being dried in a vacuum oven at 60°C for 6 hours. The dried polymer solid product was dissolved in N,N-dimethylacetamide and tested for parameters such as molecular weight and molecular weight distribution using a gel permeation chromatography analyzer. The test results are summarized in Table 1. The dried polymer product was placed in a 210°C oven and dried for 10 minutes before removal. The poly(p-hydroxystyrene) partially lost its tert-butyloxycarbonyl group, resulting in a weight loss of approximately 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 no light polymerization is performed.

[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] Experimental results demonstrate that the monothiol compound used as a photocatalyst exhibits low initiation efficiency and monomer conversion, resulting in a lower molecular weight of the polymerized product compared to Example 1, a broader molecular weight distribution, and poor reaction controllability. The results are shown in Table 1. This demonstrates that only the photocatalyst of the present invention can produce a film-forming resin with a narrow molecular weight distribution.

[0087] Comparative Example 3

[0088] 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 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. 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 in Example 1. The effect of temperature on the molecular weight distribution of poly(p-hydroxystyrene) photoresist film-forming resin was investigated. 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 better, PDI < 1.2; 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 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] From the table above, we can see 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 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.

[0105] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection 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; The polymerization reaction system includes a photocatalyst, a polymerization monomer, a chain transfer agent and a solvent, the photocatalyst is a polythiol, and the polythiol includes one or more of 1,2-ethanedithiol, 1,3-propylenedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrathioglycolate and pentaerythritol tetra-3-mercaptopropionate; The concentration of the polythiol in the polymerization reaction system is 0.2 to 10 μL / mL; 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; The polymerizable monomer includes a tert-butyloxycarbonyl-protected p-hydroxystyrene monomer; The photoinitiation is a free radical polymerization reaction in the absence of oxygen, ultraviolet light or visible light; the wavelength of the ultraviolet light is 260-390 nm, the wavelength of the visible light is 340-540 nm, and the light power density is 1-20 mW / cm 2 ; The preparation method uses reversible addition-fragmentation chain transfer polymerization technology to carry out free radical polymerization reaction under light initiation.

2. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 1, wherein: The polymerization reaction temperature is 25-45°C.

3. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 1, wherein: The mass fraction of the tert-butyloxycarbonyl-protected p-hydroxystyrene monomer in the polymerization reaction system is 10-60%.

4. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 1, wherein: The polymerizable monomers also include comonomers.

5. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 4, characterized in that: The comonomer includes one or more of methyl acrylate, ethyl acrylate, tert-butyl acrylate and tert-butyl methacrylate.

6. The method for preparing a poly(p-hydroxystyrene) photoresist film-forming resin according to claim 4, wherein: 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 100-1200:1; And / or, the solvent is one or more of tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

7. 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.

8. A poly(p-hydroxystyrene) photoresist film-forming resin prepared by the method according to any one of claims 1 to 7, characterized in that: The PDI of the film-forming resin is less than 1.2.

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