Acrylate copolymer, preparation method and application thereof, and photoresist composition

Abstract

The invention belongs to the field of semiconductor manufacturing, and particularly provides an acrylate copolymer, a preparation method and application thereof and a photoresist composition. The acrylate copolymer comprises a structural unit I with a structure shown in a formula 1, a structural unit II with a structure shown in a formula 2 and a structural unit III with a structure shown in a formula 3, and when the acrylate copolymer is used as ArF photoresist resin, the photoresist has high light transmittance and high resolution under the wavelength of 193 nm and also has excellent etching resistance.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing, specifically relating to an acrylate copolymer, its preparation method and application, and a photoresist composition. Background Technology

[0002] The continuous advancement of semiconductor manufacturing processes is driving the shrinking of integrated circuit feature sizes, with process nodes now reaching 7nm, 5nm, and even more advanced stages. In this process, photolithography, as a crucial step in pattern transfer, faces increasingly stringent requirements for precision and resolution. ArF lithography, based on a 193nm wavelength, has become an indispensable patterning method in advanced processes due to its ability to achieve higher pattern resolution with a shorter exposure wavelength.

[0003] Photoresist is the core material in photolithography, and its performance directly determines the accuracy of pattern transfer and the final characteristics of the device. Photoresist typically comprises a resin matrix, photosensitive components, and solvents. The photoresist resin is usually a polymer with specific functions formed by the polymerization of one or more monomers. As a film-forming material, the resin constitutes the backbone of the photoresist, and its molecular structure directly determines the mechanical properties, optical characteristics, thermal stability, and chemical resistance of the photoresist. Therefore, the design and synthesis of photoresist resins are central to the development of photoresist technology. In ArF lithography, the photoresist resin needs to possess high transmittance, high resolution, good film-forming properties, and excellent etch resistance at a wavelength of 193nm. These properties collectively ensure that the photoresist can achieve high-fidelity pattern transfer during exposure, development, and subsequent etching steps.

[0004] In traditional KrF lithography (248nm), poly(p-hydroxystyrene) (PHS) resins are commonly used. Their benzene ring structure provides good etch resistance, but this structure exhibits strong absorption at 193nm, leading to a significant decrease in transmittance. To address this, ArF photoresist systems have been proposed, using alicyclic polymers as a resin base. By introducing alicyclic structural units such as norbornene and adamantyl, they achieve a certain level of mechanical strength and etch resistance while maintaining high transmittance. However, as integrated circuit manufacturing processes move towards higher aspect ratios and finer patterns, especially in nanoscale pattern fabrication and advanced plasma etching processes, the molecular architecture of existing alicyclic resin systems faces significant bottlenecks in the synergistic optimization of etch resistance, resolution, and transmittance. It is difficult to further improve etching durability while maintaining high transmittance and high resolution, which severely restricts the fidelity of pattern transfer and the expansion of the process window.

[0005] Therefore, it is necessary to develop new photoresist resin systems to better meet the requirements of continuous miniaturization processes. Summary of the Invention

[0006] The present invention aims to provide an acrylate copolymer, its preparation method and application, and a photoresist composition thereof. When the acrylate copolymer is used as an ArF photoresist resin, the photoresist can exhibit both high transmittance and high resolution at a wavelength of 193 nm, while also possessing excellent etching resistance.

[0007] A first aspect of the present invention provides an acrylate copolymer comprising structural unit I as shown in Formula 1, structural unit II as shown in Formula 2, and structural unit III as shown in Formula 3:

[0008] in," " indicates a connecting bond, R1, R2 and R4 are each independently hydrogen or methyl, L is -O-, a single bond or an alkylene group with 1 to 4 carbon atoms, R3 is selected from substituted cycloalkyl groups with 7 to 15 carbon atoms, oxygen-containing heterocycloalkyl groups with 3 to 8 carbon atoms, and cycloalkyl ester groups with 4 to 8 carbon atoms, and the substituent in R3 is methyl; R5 is an alkylene group with 1 to 8 carbon atoms or a cycloalkylene group with 5 to 10 carbon atoms, and n is 0 or 1.

[0009] In some embodiments of the present invention, the molar ratio of structural unit I, structural unit II and structural unit III is c1 / c2 / c3, where c1 is 3~5, c2 is 2~4, c3 is 2~4, and c1+c2+c3=10.

[0010] In some embodiments of the present invention, the acrylate copolymer has a weight-average molecular weight of 5,000 to 20,000 and a molecular weight distribution index of 1.20 to 2.50.

[0011] In some embodiments of the present invention, L is -O-, methylene, or ethylene.

[0012] In some embodiments of the present invention, R3 is selected from any one of the following groups:

[0013] In some embodiments of the present invention, R5 is selected from methylene, ethylene, n-propylene, n-butylene, cyclopentylene, cyclohexylene, or adamantylene.

[0014] A second aspect of the present invention provides a method for preparing the acrylate copolymer described in the first aspect of the present invention, comprising: polymerizing a comonomer in the presence of a first organic solvent and an initiator to form the acrylate copolymer, wherein the comonomer comprises a first monomer with a structure as shown in formula a, a second monomer with a structure as shown in formula b, and a third monomer with a structure as shown in formula c.

[0015] In formulas a to c, R1, R2, and R4 are each independently hydrogen or methyl, L is -O-, a single bond, or an alkylene group with 1 to 4 carbon atoms, R3 is selected from substituted cycloalkyl groups with 7 to 15 carbon atoms, oxygen-containing heterocycloalkyl groups with 3 to 8 carbon atoms, or cycloalkyl ester groups with 4 to 8 carbon atoms, and the substituent of R3 is methyl; R5 is an alkylene group with 1 to 8 carbon atoms or a cycloalkylene group with 5 to 10 carbon atoms, and n is 0 or 1.

[0016] In some embodiments of the present invention, based on the total molar amount of the comonomers, the molar amount of the first monomer accounts for 30% to 50%, the molar amount of the second monomer accounts for 20% to 40%, and the molar amount of the third monomer accounts for 20% to 40%.

[0017] In some embodiments of the present invention, the polymerization reaction is carried out at a temperature of 50-80°C and for a reaction time of 1-8 hours.

[0018] In some embodiments of the present invention, the initiator is one or more of azobisisobutyronitrile, benzoyl peroxide, tert-butyl peroxide-2-ethylhexanoate, azobisisoheptanenitrile, dimethyl azobisisobutyronitrile, tert-butyl peroxide, and dicumyl peroxide.

[0019] In some embodiments of the present invention, the initiator is used in an amount of 0.1% to 3% of the total mass of the comonomer.

[0020] In some embodiments of the present invention, the first organic solvent is selected from one or more of tetrahydrofuran, propylene glycol methyl ether acetate, propylene glycol methyl ether, cyclohexanone, ethyl lactate, N,N-dimethylformamide, and N-methylpyrrolidone.

[0021] A third aspect of the present invention provides the application of the acrylate copolymers described in the first aspect of the present invention in the preparation of photoresists.

[0022] A fourth aspect of the present invention provides a photoresist composition comprising an ArF photoresist resin and a second organic solvent, wherein the ArF photoresist resin is an acrylate copolymer as described in the first aspect of the present invention.

[0023] In some embodiments of the present invention, the photoresist composition further comprises a photoacid-generating agent.

[0024] In some embodiments of the present invention, based on the total weight of the photoresist composition, the mass content of the photoresist resin is 6% to 20%, the mass content of the photoacid generator is 0.1% to 2%, and the mass content of the second organic solvent is 78% to 93%.

[0025] The acrylate copolymer provided by this invention can be used as an ArF photoresist resin. This copolymer is formed by copolymerizing a sulfur-containing lactone-based monomer (first monomer), an acid-protected monomer (second monomer), and a polar monomer (third monomer). The sulfur-containing lactone-based monomer introduces structural units with a thiooxadiabicycloalkanone backbone into the copolymer. These units, through the synergistic effect of a high-carbon content rigid bridging ring and a saturated lactone ring, significantly improve plasma etching resistance while regulating light absorption behavior at 193 nm wavelength by leveraging the electronic properties of sulfur atoms and the saturated ring, ensuring high transmittance during exposure. The appropriate polarity provided by the lactone ring allows the resin to achieve excellent solubility contrast in alkaline developer, resulting in clear patterns with regular edges and low line roughness. The acid-protected monomer in the resin undergoes a deprotection reaction after exposure to achieve patterning. The hydroxyl-containing monomer (i.e., the polar monomer) improves the adhesion between the photoresist and the substrate, preventing pattern detachment during development. While maintaining high light transmittance and high etching resistance, this resin enables the polymer chains to exhibit good solubility contrast in alkaline developing solutions, which is beneficial for achieving high-resolution imaging.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0027] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] The "scope" disclosed in this invention is defined in the form of a lower limit and / or an upper limit, whereby a given scope is defined by selecting a lower limit and / or an upper limit. This scope may or may not include endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form an undefined scope, and any lower limit can be combined with other lower limits to form an undefined scope, similarly, any upper limit can be combined with any other upper limit to form an undefined scope. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and can be combined with any other point or single value, or with other lower or upper limits, to form an undefined scope.

[0029] In this invention, the terms "first", "second", "third", "I", "II", and "III" are used only for distinguishing and descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0030] Unless otherwise specified, all embodiments and optional embodiments of the present invention may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present invention.

[0031] In a first aspect, the present invention provides an acrylate copolymer comprising structural unit I as shown in Formula 1, structural unit II as shown in Formula 2, and structural unit III as shown in Formula 3:

[0032] in," " indicates a connection key.

[0033] In Formula 1, R1 is hydrogen or methyl. Specifically, the structural unit I is:

[0034] In Formula 2, R2 is hydrogen or methyl, and L is -O-, a single bond, or an alkylene group having 1 to 4 carbon atoms (e.g., methylene, ethylene, n-propylene, n-butylene). As some preferred examples, L is -O-, a single bond, methylene, or ethylene.

[0035] In Formula 2, R3 represents an acid-unstable group and is selected from substituted cycloalkyl groups with 7 to 15 carbon atoms, oxygen-containing heterocycloalkyl groups with 3 to 8 carbon atoms, and cycloalkyl ester groups with 4 to 8 carbon atoms. The substituent in R3 is methyl. The number of substituents in R3 can be one or more (e.g., 2, 3, 4, 5). When the number of substituents is ≥2, the types of substituents can be the same or different.

[0036] In some embodiments, R3 is selected from any one of the following groups: .

[0037] In Formula 3, R4 is hydrogen or methyl, R5 is an alkylene group with 1 to 8 carbon atoms or a cycloalkylene group with 5 to 10 carbon atoms, and n is 0 or 1.

[0038] In some embodiments, R5 is selected from methylene (-CH2-), ethylene (-CH2CH2-), n-propylene (-CH2CH2CH2-), n-butylene (-CH2CH2CH2CH2-), cyclopentylene, cyclohexylene, or adamantylene.

[0039] In some embodiments, the molar ratio of structural unit I, structural unit II, and structural unit III in the acrylate copolymer is c1 / c2 / c3. Wherein, c1 is 3 to 5, for example, 3, 4, or 5; c2 is 2 to 4, for example, 2, 2.5, 3, or 4; c3 is 2 to 4, for example, 2, 2.5, 3, or 4; and c1 + c2 + c3 = 10.

[0040] In some embodiments, the weight-average molecular weight (Mw) of the acrylate copolymer is 5000~20000, for example 6000, 7000, 7200, 7500, 8000, 8200, 8600, 9150, 9400, 9600, 10050, 11500, 12000, 12800, 13000, 15000, 17500, 18000, etc., and the molecular weight distribution index (PDI) is 1.20~2.50, for example 1.20, 1.45, 1.52, 1.55, 1.65, 1.72, 1.75, 1.83, 1.85, 1.90, 1.94, 2.02, etc. The molecular weight and distribution of the acrylate copolymer can be determined by gel permeation chromatography (GPC).

[0041] In a second aspect, the present invention provides a method for preparing the acrylate copolymer described in the first aspect of the present invention, the method comprising: polymerizing a comonomer in the presence of a first organic solvent and an initiator to form the acrylate copolymer, wherein the comonomer comprises a first monomer with a structure as shown in formula a, a second monomer with a structure as shown in formula b, and a third monomer with a structure as shown in formula c.

[0042] The definitions of R1~R5, L and n are as described in the first aspect of this invention and will not be repeated here.

[0043] In this invention, based on the total molar amount of the comonomers, the first monomer accounts for 30% to 50% of the molar amount, for example, 30%, 35%, 40%, 50%, etc.; the second monomer accounts for 20% to 40% of the molar amount, for example, 20%, 25%, 30%, 40%, etc.; and the third monomer accounts for 20% to 40% of the molar amount, for example, 20%, 25%, 30%, 40%, etc. Furthermore, the molar ratio of each structural unit in the acrylate copolymer can be calculated based on the amount of each monomer added.

[0044] The method of the present invention prepares the acrylate copolymer by solution free radical polymerization. The first organic solvent is not particularly limited, as long as it can uniformly dissolve each comonomer and initiator. Specific examples of the first organic solvent include, but are not limited to, one or more of tetrahydrofuran (THF), propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME), cyclohexanone, ethyl lactate, N,N-dimethylformamide, and N-methylpyrrolidone. As some examples, the ratio of the amount of the first organic solvent to the total mass of the comonomer is (1.5~5):1, for example, 1.5:1, 1.8:1, 2.0:1, 2.5:1, 2.7:1, 3.2:1, 3.8:1, 4:1, 5:1, etc.

[0045] In this invention, the polymerization reaction can be carried out in the presence of an inert gas, such as nitrogen or argon.

[0046] In this invention, the initiator can be selected from various oil-soluble initiators. As some preferred examples, the initiator is selected from one or more of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), tert-butyl peroxide-2-ethylhexanoate (TBPEH), azobisisoheptanenitrile (ABVN), dimethyl azobisisobutyrate, tert-butyl peroxide, and dicumyl peroxide.

[0047] In some embodiments, the initiator is used in an amount of 0.1% to 3% of the total mass of the comonomer, for example, 0.1%, 0.3%, 0.5%, 0.8%, 0.9%, 1%, 1.5%, 1.8%, 2%, 2.5%, 3%, etc.

[0048] In some embodiments, the polymerization reaction temperature is 50~80℃, for example 55℃, 60℃, 65℃, 70℃, 72℃, 75℃, 77℃, 80℃, etc., and the reaction time is 1~8h, for example 1h, 1.5h, 2h, 2.5h, 3h, 4h, 5h, 7h, 8h, etc.

[0049] In some implementations, the method includes the following steps: (1) Dissolve the first monomer, the second monomer and the third monomer in the first organic solvent to obtain a monomer solution; (2) Under the protection of an inert gas, an initiator is added to the monomer solution and stirred until homogeneous. Then, the temperature is raised to 50-80°C and stirred for 1-8 hours to form an acrylate copolymer.

[0050] To obtain a high-purity product, the method preferably further includes: (3) After cooling the reaction solution obtained in step (2), add an undesirable solvent (such as methanol) to precipitate the solid precipitate, then separate the solid precipitate and dry it to obtain a solid acrylate copolymer.

[0051] Thirdly, the present invention provides the application of the acrylate copolymers described in the first aspect of the present invention in the preparation of photoresists.

[0052] A fourth aspect of the present invention provides a photoresist resin composition comprising an ArF photoresist resin and a second organic solvent, wherein the ArF photoresist resin is an acrylate copolymer as described in the first aspect of the present invention.

[0053] In some embodiments, the photoresist composition further comprises a photoacid-generating agent. Under these conditions, the photoresist resin composition is a chemically amplified positive system. During exposure, the photoacid-generating agent decomposes under light to produce a strong acid; this strong acid acts as a catalyst in subsequent heat treatment, initiating a deprotection reaction of the acid-protecting groups in the copolymer, resulting in a significant increase in the polarity of the polymer in the exposed area. This makes its dissolution rate in the alkaline developer much higher than that in the unexposed area, thereby forming a positive pattern after development.

[0054] In some embodiments, the mass content of the photoresist resin can be 6% to 20% based on the total weight of the photoresist resin composition, for example, 6%, 7%, 8%, 10%, 12%, 14%, 15%, 15%, 18%, etc.

[0055] In this invention, the photo-induced acid-producing agent is typically selected from one or more of onium salts, oxime sulfonates, and N-sulfonyloxyimides. Specific examples of onium salt acid-producing agents include, but are not limited to, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluorobutanesulfonate, and 4-tert-butylphenyl diphenylsulfonium trifluoromethanesulfonate. Specific examples of oxime sulfonate acid-producing agents include, but are not limited to, α-(benzenesulfonyloxyimino)-4-methylacetophenone and α-(camphorsulfonyloxyimino)-4-methoxyacetophenone. Specific examples of N-sulfonyloxyimide acid-producing agents include, but are not limited to, N-hydroxy-5-norbornene-2,3-dicarboximide trifluoromethanesulfonate and N-hydroxynaphthalimide p-toluenesulfonate.

[0056] In some embodiments, the mass content of the photoacid generator can be 0.1% to 2% based on the total weight of the photoresist resin composition, for example, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 2%, etc.

[0057] The present invention does not particularly limit the type of the second organic solvent, as long as it can sufficiently dissolve or disperse the other components in the composition. As some specific examples, the second organic solvent may be selected from one or more of propylene glycol methyl ether acetate, propylene glycol methyl ether, ethyl lactate, butyl lactate, cyclohexanone, and N-methylpyrrolidone. As some specific examples, the second organic solvent is a mixed solvent of propylene glycol methyl ether acetate and propylene glycol methyl ether, and the mass ratio of the two is (3~7):1.

[0058] In some embodiments, the mass content of the second organic solvent can be 78% to 93% based on the total weight of the photoresist resin composition, for example, 80%, 82%, 84%, 85%, 88%, 90%, 92%, 93%, etc.

[0059] In some embodiments, the photoresist resin composition can typically be prepared by uniformly mixing the photoresist resin, the photoacid generator, and the second organic solvent, and optionally by filtration.

[0060] The following describes embodiments of the present invention. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0061] The following synthesis examples are used to illustrate the lactone monomers C1-C2 used in the examples and their preparation methods.

[0062] Synthesis Example 1: Synthesis of lactone monomer C1

[0063] (1) Under nitrogen protection, thiophene (296g, 3.52mol) and methyl acrylate (100g, 1.16mol) were placed in a 500mL round-bottom flask, placed in an ice-salt bath at -20°C and stirred. 15mL of boron trifluoride ether solution (BF3 concentration 47%) was slowly added to the flask with a syringe, and then the reaction was stirred in an ice bath at 5°C for 10h. After the reaction was completed, the resulting reaction solution was transferred to a separatory funnel, diluted with 200 mL of ethyl acetate, shaken thoroughly, allowed to stand for separation, and the organic phase was separated. The organic phase was washed successively with distilled water (150 mL × 2), 5 wt% sodium bicarbonate aqueous solution (150 mL × 2), and saturated sodium chloride aqueous solution (150 mL), then dried with anhydrous sodium sulfate, filtered to remove the drying agent, and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was separated by column chromatography (eluent: petroleum ether (PE) / ethyl acetate (EA) = 7 / 2, v / v) to obtain a transparent light yellow oily substance, namely product methyl 7-thiabicyclo[2.2.1]hept-5-ene-2-carboxylate (166.9 g, yield 84.1%), abbreviated as product a1. The mass spectrometry (LCMS (ESI) m / z) of product a1 is [M+H].+ : 171.2378.

[0064]

[0065] (2) Product a1 (165 g, 0.96 mol) and 0.6 L of 10 wt% sodium hydroxide aqueous solution were added to a 2 L reaction flask and stirred at room temperature for about 12 h until the reaction of product a1 was complete as monitored by TLC (developing solvent: PE / EA = 1 / 1, v / v). After the reaction was completed, dilute hydrochloric acid was added until the pH of the reaction solution was lower than 2, and then extracted with ethyl acetate (250 mL × 3). The organic phases were combined, washed with saturated NaCl aqueous solution (200 mL), dried with anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain product 7-thiabicyclo[2.2.1]hept-5-en-2-carboxylic acid (140 g, yield 92.9%), abbreviated as product a2. The mass spectrometry LCMS (ESI) m / z [M+H]+ of product a2 was 157.2078.

[0066]

[0067] (3) Product a2 (130 g, 0.83 mol) was placed in a 1 L round-bottom flask, and 200 mL of formic acid and 320 mL of 35 wt% hydrogen peroxide were added. The mixture was heated to 45 °C and stirred until gas was generated. Then, it was cooled to room temperature and stirred for 30 min. After the complete consumption of product a2 was detected by LCMS, the reaction solution was evaporated under reduced pressure to obtain a solid. The solid was recrystallized from ethanol to obtain product 6-hydroxytetrahydro-3,5-methanethiopheno[3,2-b]furan-2(3H)-one (85 g, yield 59.2%), abbreviated as product a3. The mass spectrometry of product a3 was LCMS (ESI) m / z [M+H]. + : 173.2078.

[0068]

[0069] (4) Add product a3 (85g, 0.49mol), triethylamine 101g and dichloromethane 100mL to a reaction flask, stir well, place in an ice-water bath, under nitrogen protection, add methacrylamide chloride (100g, 0.96mol) and stir for 0.5h, then heat to room temperature and continue stirring for 4h. Then use TLC to detect until product a3 is completely consumed and the reaction is complete (developing solvent: PE / EA = 1 / 1, v / v), then add 300mL of 10wt% NaHCO3 aqueous solution and stir for 1h, then extract with ethyl acetate (200mL×3), combine the organic phases, wash with saturated NaCl solution (150mL), add anhydrous sodium sulfate to dry, filter the drying agent, and concentrate the filtrate under reduced pressure to obtain the crude product. The crude product was separated by column chromatography (eluent: PE / EA = 1 / 1, v / v) to give the product 2-oxohexahydro-3,5-methyl-bridged thiophene[3,2-]methacrylic acid. b Furan-6-yl ester (92.5 g, yield 78.5%), i.e. lactone monomer C1.

[0070] NMR characterization results of monomer C1, 1 H NMR (500 MHz, Chloroform- d ) δ: 6.20-6.19(m,1H), 6.09-5.98(m, 1H), 5.51-5.41 (m, 2H), 4.45-4.36(m, 1H), 4.50-4.41(m, 1H),3.22-3.31 (m, 1H), 2.87-2.96(m, 1H), 2.51-2.43(m, 1H), 2.05(s, 3H). LCMS (ESI) mass spectrometry of monomer C1 m / z [M+H] + : 241.2778.

[0071] Synthesis Example 2: Synthesis of lactone monomer C2 The lactone monomer C2 was synthesized according to the method of Synthesis Example 1, except that in step (4), methacryloyl chloride was replaced with the same molar amount of acryloyl chloride, thereby obtaining lactone monomer C2 with the structure shown below (81.3 g, yield 73.1%). LCMS (ESI) m / z [M+H] + :227.2475.

[0072]

[0073] Preparation Example 1 Add lactone monomer C1 (48.05 g, 0.20 mol), 2-tetrahydrofuranyl methacrylate (23.43 g, 0.15 mol), 4-hydroxycyclohexyl methacrylate (27.63 g, 0.15 mol), and 350 mL of anhydrous tetrahydrofuran (THF) to a round-bottom flask equipped with a reflux condenser. Stir until dissolved. Then, under argon protection, add 1.24 g of azobisisobutyronitrile and stir until homogeneous. Heat to 65 °C and stir for 2 h. After the reaction is complete, cool the resulting reaction solution to room temperature and add it dropwise to 500 mL of methanol over 30 min with stirring. A precipitate forms. After the addition is complete, continue stirring for 30 min, and collect the precipitate by filtration. After vacuum drying of the precipitate, acrylate copolymer P1 (80.23 g, yield 81%) was obtained. P1 has the structure shown in Formula 1-a below, with the molar ratio of the three structural units x∶y∶z being 4∶3∶3. P1 has Mw=8380 and PDI=1.84.

[0074] Formula 1-a Preparation Example 2 Add lactone monomer C1 (48.05 g, 0.20 mol), 2-oxotetrahydro-2H-pyran-3-yl acrylate (CAS: 1370460-77-7, 25.52 g, 0.15 mol), methacrylic acid (12.91 g, 0.15 mol), and 350 mL of anhydrous THF to a round-bottom flask equipped with a reflux condenser. Stir until dissolved. Then, under argon protection, add 1.24 g of azobisisobutyronitrile and stir until homogeneous. Heat to 60 °C and stir for 3 h. After the reaction is complete, cool the resulting reaction solution to room temperature and add it dropwise to 500 mL of methanol over 30 min with stirring. A precipitate forms. After the addition is complete, continue stirring for 30 min, and collect the precipitate by filtration. After vacuum drying of the precipitate, acrylate copolymer P2 (66.01 g, yield 76%) was obtained. P2 has the structure shown in Formula 1-b below, with the molar ratio of the three structural units x∶y∶z being 4∶3∶3. P2 has Mw=11300 and PDI=1.75.

[0075] Formula 1-b Preparation Example 3 Add lactone monomer C1 (48.05 g, 0.20 mol), 2-tetrahydropyranoacrylate (23.43 g, 0.15 mol), and methacrylic acid (12.91 g, 0.15 mol) to a round-bottom flask equipped with a reflux condenser, and then to 300 mL of anhydrous THF. Stir until dissolved. Then, under argon protection, add 1.15 g of azobisisobutyronitrile and stir until homogeneous. Heat to 60 °C and stir for 2 h. After the reaction is complete, cool the resulting reaction solution to room temperature and add it dropwise to 500 mL of methanol over 30 min with stirring. A precipitate forms. After the addition is complete, continue stirring for 30 min, and collect the precipitate by filtration. Dry the precipitate under vacuum. ， Acrylate copolymer P3 (66.16 g, 78% yield) was obtained. P3 has the structure shown in Formula 1-c below, with the molar ratio of the three structural units x∶y∶z being approximately 4∶3∶3. P3 has Mw=9780 and PDI=1.94.

[0076] Formula 1-c Preparation Example 4 To a round-bottom flask equipped with a reflux condenser, lactone monomer C1 (48.05 g, 0.20 mol), 2-methyl-2-adamantyl methacrylate (35.15 g, 0.15 mol), hydroxyethyl methacrylate (19.52 g, 0.15 mol), and 370 mL of anhydrous THF were added and stirred until dissolved. Then, under argon protection, 1.54 g of azobisisobutyronitrile was added and stirred until homogeneous. The mixture was heated to 70 °C and stirred for 2 h. After the reaction was complete, the resulting reaction solution was cooled to room temperature and added dropwise to 500 mL of methanol over 30 min with stirring. A precipitate formed. After the addition was complete, stirring was continued for 30 min, and the precipitate was collected by filtration. The precipitate was dried under vacuum to obtain acrylate copolymer P4 (86.28 g, yield 84%). P4 has the structure shown in Equation 1-d, with the molar ratio of the three structural units x∶y∶z=4∶3∶3, Mw=10560, and PDI=2.02.

[0077] Equation 1-d Preparation Example 5 To a round-bottom flask equipped with a reflux condenser, lactone monomer C2 (56.66 g, 0.25 mol), 1-methylcyclohexyl methacrylate (27.33 g, 0.15 mol), hydroxyethyl methacrylate (13.01 g, 0.10 mol), and 320 mL of anhydrous THF were added and stirred until dissolved. Then, under argon protection, 1.84 g of azobisisobutyronitrile was added and stirred until homogeneous. The mixture was heated to 75 °C and stirred for 2 h. After the reaction was complete, the resulting reaction solution was cooled to room temperature and added dropwise to 500 mL of methanol over 30 min with stirring. A precipitate formed. After the addition was complete, stirring was continued for 30 min, and the precipitate was collected by filtration. After drying the precipitate, acrylate copolymer P5 (75.87 g, 78% yield) was obtained. P5 has the structure shown in Equation 1-e, with the molar ratio of the three structural units x∶y∶z=5∶3∶2, Mw=7460, and PDI=1.92.

[0078] Equation 1-e Comparative Preparation Example 1 Acrylate copolymers were prepared according to the method of Preparation Example 1, except that the lactone monomer C1 was replaced with an equimolar amount of 4-hydroxycyclohexyl methacrylate. The prepared acrylate copolymer (68.33 g) was designated as DP1, which had the structure shown in Formula 1-f, with a molar ratio of the two structural units y∶z=3∶7, Mw=8732, and PDI=1.80.

[0079] Equation 1-f Comparative Preparation Example 2 Acrylate copolymers were prepared according to the method of Preparation Example 1, except that the lactone monomer C1 was replaced with an equimolar amount of 2-tetrahydrofuranyl methacrylate. The prepared acrylate copolymer (56.43 g) was designated as DP2, which had the structure shown in Formula 1-f. The molar ratio of the two structural units y:z was 7:3, and DP2 had Mw = 11500 and PDI = 1.91.

[0080] Comparative preparation example 3 Acrylate copolymers were prepared according to the method of Preparation Example 4, except that the lactone monomer C1 was replaced with an equimolar amount of 2-carboxy-4-norbornolactone-5-methacrylate. The prepared acrylate copolymer (74.73 g) was designated as DP3, which had the structure shown in Formula 1-g, with a molar ratio of x∶y∶z of 4∶3∶3. DP3 had Mw=9460 and PDI=1.77.

[0081] Formula 1-g Example 1 At room temperature, 2.5g of acrylate copolymer P1, 0.2g of photoacid generator (triphenylsulfonium trifluoromethanesulfonate, CAS: 66003-78-9), 12g of propylene glycol methyl ether acetate and 3g of propylene glycol methyl ether were sequentially added to a container, sealed, and placed on a magnetic stirrer. The mixture was stirred continuously at room temperature for 5 hours to form a homogeneous solution. The solution was then filtered through a 0.2μm filter membrane to obtain the photoresist composition, denoted as A1.

[0082] Examples 2-5 The photoresist compositions were prepared according to the method of Example 1, except that copolymer P1 was replaced sequentially with copolymers P2, P3, P4, and P5, and the prepared photoresist compositions were denoted as A2, A3, A4, and A5, respectively.

[0083] Comparative Examples 1-3 The photoresist composition was prepared according to the method of Example 1, except that copolymer P1 was replaced with DP1, DP2, and DP3 respectively, and the prepared photoresist compositions were denoted as B1, B2, and B3 respectively.

[0084] Test case The test examples were used to perform performance tests on the photoresist compositions A1~A5 and B1~B3 of the above embodiments and comparative examples.

[0085] 1. Etching resistance test Photoresist compositions A1-A5 and B1-B3 were spin-coated onto a silicon wafer and baked at 105°C for 100 seconds to form a film. The thickness of this film was measured to obtain the initial film thickness, denoted as L1. The film was then etched using CF4 gas under the following conditions: processing chamber pressure 40 Pa, RF power 1300 W, CF4 gas flow rate 25 mL / min, and etching time 50 seconds. After etching, the film thickness was measured again to obtain the post-etched thickness, denoted as L2. The etching rate was calculated using the formula: Etching rate = (L1 - L2) / Etching time.

[0086] 2. Photolithography performance testing Photoresist compositions A1-A5 and B1-B3 were spin-coated onto a silicon wafer, and then pre-baked at 95°C for 100 seconds. The photoresist film was then exposed using an ArF laser expocer, followed by post-baking at 110°C for 90 seconds. Finally, it was developed using a 2.38 wt% tetramethylammonium hydroxide (TMAH) developer for 60 seconds to obtain the corresponding photolithographic pattern.

[0087] Resolution: By using a scanning electron microscope at the optimal focal length and adjusting the exposure dose, the smallest feature size that can clearly and stably form a 1:1 linewidth / line spacing pattern is found, and this size is denoted as the resolution.

[0088] 3. Transmittance Test: Photoresist compositions A1~A5 and B1~B3 were spin-coated onto a silicon wafer, respectively. The wafer was then baked at 105℃ for 90 seconds to form a photoresist film with a thickness of 0.3μm. The transmittance of the photoresist film was tested at a wavelength of 193nm using a UV-Vis spectrophotometer. This transmittance was used as a measure of transparency in the far-ultraviolet region; higher transmittance indicates better transparency. The transmittance (T) is calculated as follows: T = (I / I0) × 100%, where I represents the intensity of light transmitted through the resist film, and I0 represents the intensity of the incident light.

[0089] The test results are shown in Table 1.

[0090] Table 1

[0091] As shown in Table 1, the acrylate copolymers P1-P5 prepared in Examples 1-5, when used as photoresist resins in photoresist compositions, exhibit significantly better transmittance and resolution than Comparative Examples 1-3 under ArF (193nm) lithography conditions, while also having lower etching rates. This demonstrates that when acrylate copolymers P1-P5 are used as ArF photoresist resins, they enable the photoresist to possess both high transmittance and high resolution, along with excellent etching resistance.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An acrylate copolymer, characterized in that, This includes structural unit I as shown in Equation 1, structural unit II as shown in Equation 2, and structural unit III as shown in Equation 3: in," " indicates a connection key. R1, R2, and R4 are each independently hydrogen or methyl. L is -O-, a single bond, or an alkylene group having 1 to 4 carbon atoms. R3 represents an acid-unstable group, and is selected from substituted cycloalkyl groups with 7 to 15 carbon atoms, oxygen-containing heterocycloalkyl groups with 3 to 8 carbon atoms, and cycloalkyl ester groups with 4 to 8 carbon atoms, and the substituent in R3 is methyl; R5 is an alkylene group with 1 to 8 carbon atoms or a cycloalkylene group with 5 to 10 carbon atoms, and n is 0 or 1.

2. The acrylate copolymer according to claim 1, characterized in that, The molar ratio of structural unit I, structural unit II and structural unit III is c1 / c2 / c3, where c1 is 3~5, c2 is 2~4, c3 is 2~4, and c1+c2+c3=10. Preferably, the acrylate copolymer has a weight-average molecular weight of 5,000 to 20,000 and a molecular weight distribution index of 1.20 to 2.

50.

3. The acrylate copolymer according to claim 1 or 2, characterized in that, L represents -O-, methylene, or ethylene; Preferably, R3 is selected from the group consisting of: 。 4. The acrylate copolymer according to any one of claims 1-3, characterized in that, R5 is selected from methylene, ethylene, n-propylene, n-butylene, cyclopentylene, cyclohexylene, or adamantylene.

5. A method for preparing the acrylate copolymer according to any one of claims 1-4, characterized in that, include: In the presence of a first organic solvent and an initiator, the comonomers are polymerized to form the acrylate copolymer, wherein the comonomers comprise a first monomer with the structure shown in formula a, a second monomer with the structure shown in formula b, and a third monomer with the structure shown in formula c. In formulas a to c, R1, R2, and R4 are each independently hydrogen or methyl. L is -O-, a single bond, or an alkylene group with 1 to 4 carbon atoms; R3 is selected from substituted cycloalkyl groups with 7 to 15 carbon atoms, oxygen-containing heterocycloalkyl groups with 3 to 8 carbon atoms, or cycloalkyl ester groups with 4 to 8 carbon atoms, and the substituent of R3 is methyl. R5 is an alkylene group with 1 to 8 carbon atoms or a cycloalkylene group with 5 to 10 carbon atoms, and n is 0 or 1.

6. The method according to claim 5, characterized in that, Based on the total molar amount of the comonomers, the molar amount of the first monomer accounts for 30% to 50%, the molar amount of the second monomer accounts for 20% to 40%, and the molar amount of the third monomer accounts for 20% to 40%.

7. The method according to claim 5 or 6, characterized in that, The polymerization reaction is carried out at a temperature of 50-80°C for 1-8 hours. Preferably, the initiator is one or more selected from azobisisobutyronitrile, benzoyl peroxide, tert-butyl peroxide-2-ethylhexanoate, azobisisoheptanenitrile, dimethyl azobisisobutyronitrile, tert-butyl peroxide, and dicumyl peroxide. Preferably, the initiator is used in an amount of 0.1% to 3% of the total mass of the comonomer; Preferably, the first organic solvent is selected from one or more of tetrahydrofuran, propylene glycol methyl ether acetate, propylene glycol methyl ether, cyclohexanone, ethyl lactate, N,N-dimethylformamide, and N-methylpyrrolidone.

8. The use of the acrylate copolymer according to any one of claims 1-4 in the preparation of photoresists.

9. A photoresist composition, characterized in that, It comprises ArF photoresist resin and a second organic solvent, wherein the ArF photoresist resin is an acrylate copolymer as described in any one of claims 1-4.

10. The photoresist composition according to claim 9, characterized in that, The photoresist composition further includes a photoacid-generating agent; Preferably, based on the total weight of the photoresist composition, the mass content of the ArF photoresist resin is 6% to 20%, the mass content of the photoacid generator is 0.1% to 2%, and the mass content of the second organic solvent is 78% to 93%.

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