Sulfonium salt type photoacid generator and photoresist composition as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photoetching materials, and particularly relates to a sulfonium salt type photoacid generator, a photoresist composition and a preparation method and application of the sulfonium salt type photoacid generator and the photoresist composition. The sulfonium salt type photoacid generator has a structure as shown in a formula (1). The photoresist composition comprises polymer resin containing an acid-sensitive group, a sulfonium salt type photoacid generator with a structure as shown in a formula (1), an acid diffusion inhibitor and a second organic solvent. The key of the invention lies in providing the sulfonium salt type photoacid generator with a specific structure, the anion part of the sulfonium salt type photoacid generator has a conjugated skeleton structure of a thiaxanthene ring and an ethynyl group, and the sulfonium salt type photoacid generator with the anion part having the thiaxanthene ring and the ethynyl group is adopted in a photoresist composition. The sensitivity, the critical dimension uniformity (CDU) and the thermal stability are improved, the line width roughness (LER) is reduced, a photoetching pattern with excellent morphology is obtained, and the method has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoetching materials, and particularly relates to a sulfonium salt type photoacid generator and a photoresist composition as well as a preparation method and application thereof. BACKGROUND

[0002] Photoresist, also known as photoresist, is a kind of etching-resistant film material whose solubility changes through the irradiation or radiation of ultraviolet light, excimer laser, X-ray, electron beam, ion beam, etc., and is mainly used for the processing of integrated circuits and semiconductor discrete devices in the electronic industry. The chemical amplification type photoresist system was proposed by Ito et al. of IBM Corporation Almanden Research Center in the early 1980s. The so-called chemical amplification is to add a photoacid generator to the photosensitive composition, which undergoes a photochemical reaction under light to generate a chemical amplification agent, such as a protonic acid or a Lewis acid. This chemical amplification agent, after the light stops, acts as a catalyst for further chemical reactions of the polymer through heating or hydrolysis, etc., to achieve the purpose of amplification, greatly improving the initial photochemical quantum efficiency. It can be seen that the photoacid generator plays a dominant role in the chemical amplification resist system, and an excellent photoacid generator will greatly improve the photosensitivity, improve the imaging quality, and be well used in industrial production.

[0003] Photoacid generator (PAG) is a kind of compound that can generate a specific acid under the irradiation of light, rays, plasma, etc. The generated acid can cause the decomposition or crosslinking reaction of acid-sensitive resin, so as to increase the solubility contrast between the light-exposed part and the non-light-exposed part. The photoacid generator is one of the key components in the chemical amplification type photoresist, and its structure and properties have a great influence on the image formed by the photoresist system. It should meet the conditions of good chemical stability, good thermal stability and high acid generation efficiency. At present, the photoacid generators of sulfonium salt and sulfonate occupy a dominant position.

[0004] The commonly used sulfonium salt type photoacid generator at present, such as triphenylsulfonium triflate, has low absorption efficiency for deep ultraviolet light (such as 193 nm, 248 nm) and EUV (13.5 nm), and requires a higher exposure dose to generate sufficient acid, so the photoetching sensitivity is low, which restricts the process efficiency. For the sulfonate type photoacid generator, the perfluorosulfonic acid molecule generated after light exposure has small volume and extremely strong acidity, and the acid diffusion rate is too fast, which leads to blurred pattern edges, increased line width roughness (LER) and poor critical dimension uniformity (CDU). SUMMARY

[0005] The present application aims at the problems of low sensitivity, poor thermal stability, large line width roughness and poor critical dimension uniformity of the existing photoacid generators in the application of photoresist, and provides a new sulfonium salt type photoacid generator, which is added into a photoresist composition, can endow the photoresist with improved thermal stability and sensitivity, and obtain a photoresist pattern with good line width roughness and critical dimension uniformity.

[0006] In a first aspect, the present application provides a sulfonium salt type photoacid generator having a structure shown in formula (1): Formula (1), In formula (1), R1, R2, R3 are each independently selected from C1-C12 alkyl, C1-C12 alkoxy or C3-C20 cycloalkyl, and a, b, c are each independently an integer from 0 to 5.

[0007] In a second aspect, the present application provides a preparation method of the above-mentioned sulfonium salt type photoacid generator. The preparation method comprises the following steps: S1. 9-ethynyl-9-thioxanthanol having a structure shown in formula (2) is subjected to a metallization reaction with an alkali metal hydride and a first organic solvent under an inert gas condition to obtain an intermediate product M1 shown in formula (3); S2. The intermediate product M1 is subjected to an ion exchange reaction with a compound M2 shown in formula (4), and the obtained reaction product is the sulfonium salt type photoacid generator shown in formula (1); Formula (2), Formula (3), Formula (4), In formula (4), R1, R2, R3 are each independently selected from C1-C12 alkyl, C1-C12 alkoxy or C3-C20 cycloalkyl, and a, b, c are each independently an integer from 0 to 5, and X - is a halogen ion.

[0008] In a preferred embodiment, in step S1, the molar ratio of the 9-ethynyl-9-thioxanthanol to the alkali metal hydride is 1:(1.1-1.3).

[0009] In a preferred embodiment, in step S1, the conditions of the metallization reaction include: the first reaction temperature is -5-5℃, and the first reaction time is 0.5-1.0h; the second reaction temperature is 15-25℃, and the second reaction time is 0.5-2.0h.

[0010] In a preferred embodiment, in step S1, the alkali metal hydride is potassium hydride and / or sodium hydride.

[0011] In a preferred embodiment, in step S1, the first organic solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide, diethyldimethyl ether, and toluene.

[0012] In a preferred embodiment, in step S2, the molar ratio of the compound M2 to the intermediate M1 is (1.3~1.8):1.

[0013] In a preferred embodiment, in step S2, the ion exchange reaction is carried out at a temperature of 15~25℃ for 12~24h.

[0014] In a third aspect, the present application provides a photoresist composition. The photoresist composition comprises a polymer resin containing acid-sensitive groups, the above-mentioned sulfonium salt photoacid generator, an acid diffusion inhibitor, and a second organic solvent.

[0015] In a preferred embodiment, the content of the polymer resin is 50~200 parts by weight, the content of the sulfonium salt photoacid generator is 1~30 parts by weight, the content of the acid diffusion inhibitor is 1~5 parts by weight, and the content of the second organic solvent is 1000~4000 parts by weight.

[0016] In a preferred embodiment, the polymer resin contains structural unit one represented by formula (5) and structural unit two represented by formula (6), or, contains structural unit one represented by formula (5) and structural unit three represented by formula (7), or, contains structural unit two represented by formula (6) and structural unit three represented by formula (7). Formula (5), Formula (6), Formula (7), In formula (5), R4 is a hydrogen atom or a C1~C3 alkyl group; In formula (6), R5 is a hydrogen atom or a C1~C3 alkyl group, and R6 is an acid-labile group; In formula (7), R7 is a hydrogen atom or a C1~C3 alkyl group, and R8 is an acid-labile group.

[0017] In a preferred embodiment, when the polymer resin contains structural unit one represented by formula (5) and structural unit two represented by formula (6), the molar ratio of structural unit one to structural unit two is (1~3):1.

[0018] In a preferred embodiment, when the polymer resin contains structural unit one represented by formula (5) and structural unit three represented by formula (7), the molar ratio of structural unit one to structural unit three is (1~3):1. In a preferred embodiment, when the polymer resin contains structural unit two represented by formula (6) and structural unit three represented by formula (7), the molar ratio of structural unit two to structural unit three is (0.5-1.5):1.

[0019] In a preferred embodiment, the acid-labile group is selected from at least one of the following structures: .

[0020] In a fourth aspect, the present application also provides the use of the above-mentioned sulfonium salt type photo-acid generator and / or photoresist composition in photolithography technology.

[0021] Beneficial effects: The key of the present application is to provide a sulfonium salt type photo-acid generator with a specific structure, the anion part of which has a conjugated skeleton structure of thioxanthene ring and ethynyl group, which on the one hand can endow the photo-acid generator with good thermal stability, and is also conducive to improving the thermal stability of the photoresist composition containing the photo-acid generator during storage and pretreatment, avoiding acid generation in the unexposed state, and improving the stability of the photoresist composition, and on the other hand, due to the presence of the conjugated skeleton structure of thioxanthene ring and ethynyl group, the sulfonium salt type photo-acid generator has a large molecular volume and rigid structure, which can limit the diffusion range of the acid in the photoresist film, improve the problems of pattern edge blur and line width roughness caused by acid diffusion, and improve the critical dimension uniformity, in addition, the sulfonium salt type photo-acid generator with the specific structure can effectively improve the light absorption efficiency and enhance the acid generation efficiency, significantly improving the sensitivity of the photoresist composition. In summary, the use of the sulfonium salt type photo-acid generator with the anion part of thioxanthene ring and ethynyl group provided by the present application in the photoresist composition is conducive to improving its sensitivity, critical dimension uniformity (CDU) and thermal stability, and reducing line width roughness (LER), obtaining a photoetching pattern with excellent morphology, and having good application prospect DETAILED DESCRIPTION The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. In addition, if not specifically stated, all embodiments and optional embodiments of the present application can 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 application.

[0022] The sulfonium salt type photo-acid generator provided by the present application has a structure represented by formula (1): Formula (1), In formula (1), R1, R2, R3 are each independently selected from C1-C12 alkyl, C1-C12 alkoxy or C3-C20 cycloalkyl. a, b, c are each independently an integer from 0 to 5, such as 0, 1, 2, 3, 4 or 5. Specific examples of C1-C12 alkyl include, but are not limited to, any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, sec-butyl, isobutyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, n-heptyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl. The chemical formula of C1-C12 alkoxy is -O-R, wherein R is C1-C12 alkyl, and specific examples of R are as described above, which will not be repeated here. Specific examples of C3-C20 cycloalkyl include, but are not limited to, any one of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl.

[0023] The preparation method of the above-mentioned sulfonium salt type photoacid generator provided by the application comprises the following steps: S1. 9-ethynyl-9-thioxanthanol having a structure shown in formula (2) is subjected to metallization reaction with alkali metal hydride and a first organic solvent under inert gas condition to obtain an intermediate product M1 shown in formula (3); S2. The intermediate product M1 is subjected to ion exchange reaction with a compound M2 shown in formula (4), and the obtained reaction product is the sulfonium salt type photoacid generator shown in formula (1).

[0024] Formula (2), Formula (3), Formula (4).

[0025] In formula (4), R1, R2, R3 are each independently selected from C1-C12 alkyl, C1-C12 alkoxy or C3-C20 cycloalkyl. a, b, c are each independently an integer from 0 to 5, such as 0, 1, 2, 3, 4 or 5. X - is any one of F - , Cl - , Br - , I - .

[0026] In the present application, in step S1, the molar ratio of 9-ethynyl-9-thioxanthanol to alkali metal hydride is preferably 1:(1.1~1.3), such as 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3 or any ratio therebetween.

[0027] In the present application, in step S1, the conditions of the metallization reaction preferably include: the first reaction temperature is -5~5℃, such as -5℃, -2℃, 0℃, 2℃, 5℃ or any value therebetween; the first reaction time is 0.5~1.0h, such as 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1.0h or any value therebetween; the second reaction temperature is 15~25℃, such as 15℃, 18℃, 20℃, 22℃, 25℃ or any value therebetween; the second reaction time is 0.5~2.0h, such as 0.5h, 1.0h, 1.5h, 2.0h or any value therebetween.

[0028] In a specific embodiment, the process of the metallization reaction can be as follows: under the protection of inert gas, 9-ethynyl-9-thioxanthanol is mixed with alkali metal hydride and first organic solvent, and then reacted at the first reaction temperature of -5~5℃ for 0.5~1.0h, followed by warming to the second reaction temperature of 15~25℃ for 0.5~2.0h, and then the intermediate product M1 is obtained. The inert gas is preferably argon and / or nitrogen.

[0029] In the present application, the alkali metal hydride is preferably potassium hydride and / or sodium hydride.

[0030] In the present application, the type of the first organic solvent is not particularly limited, as long as it can form a homogeneous system with 9-ethynyl-9-thioxanthanol and alkali metal hydride and will not hinder the metallization reaction, and specific examples include but are not limited to at least one of tetrahydrofuran, N,N-dimethylformamide, diethyl glycol dimethyl ether, toluene.

[0031] In the present application, in step S2, the molar ratio of the compound M2 to the intermediate product M1 is preferably (1.3~1.8):1, such as 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1 or any ratio therebetween.

[0032] In the present application, in step S2, the conditions of the ion exchange reaction preferably include: the temperature is 15~25℃, such as 15℃, 18℃, 20℃, 22℃, 25℃ or any value therebetween; the time is 12~24h, such as 12h, 15h, 18h, 20h, 22h, 24h or any value therebetween.

[0033] In a specific embodiment, the ion exchange reaction can be carried out as follows: under inert gas protection, compound M2 is mixed with a first organic solvent to form a solution, the mixed solution is mixed with intermediate product M1 at -5-5℃, and then the temperature is raised to 15-25℃ for ion exchange reaction for 12-24h. The reaction product mixture obtained after ion exchange reaction is preferably subjected to extraction, drying, concentration, and purification treatment to obtain the sulfonium salt type photoacid generator. More preferably, the reaction product mixture obtained after ion exchange reaction is preferably subjected to dichloromethane extraction, Na2SO4 drying, evaporation concentration, and silica gel column chromatography purification treatment to obtain the sulfonium salt type photoacid generator.

[0034] In the present application, the compound M2 can be any compound having the structure shown in formula (4), and specific examples thereof include, but are not limited to, at least one of triphenylsulfonium chloride, triphenylsulfonium bromide, triphenylsulfonium iodide, 4-tert-butylphenyl-diphenylsulfonium chloride, 4-tert-butylphenyl-diphenylsulfonium bromide, mesitylsulfonium chloride, (4-cyclohexylphenyl)diphenylsulfonium bromide, and (4-cyclohexylphenyl)diphenylsulfonium chloride.

[0035] The photoresist composition provided by the present application comprises a polymer resin containing an acid-sensitive group, a sulfonium salt type photoacid generator having the structure shown in formula (1), an acid diffusion inhibitor, and a second organic solvent.

[0036] In the present application, the content of the polymer resin is preferably 50-200 parts by weight, such as 50, 80, 100, 120, 150, 180, 200 parts by weight, or any value therebetween. The content of the sulfonium salt type photoacid generator is preferably 1-30 parts by weight, such as 1, 5, 10, 15, 20, 25, 30 parts by weight, or any value therebetween. The content of the acid diffusion inhibitor is preferably 1-5 parts by weight, such as 1, 2, 3, 4, 5 parts by weight, or any value therebetween. The content of the second organic solvent is preferably 1000-4000 parts by weight, such as 1000, 1500, 2000, 2500, 3000, 3500, 4000 parts by weight, or any value therebetween.

[0037] In the present application, the kind and structure of the polymer resin are not particularly limited, and any of the resin materials used in the conventional photoresist materials containing acid-sensitive groups can be used. The polymer resin preferably contains structural unit one represented by formula (5) and structural unit two represented by formula (6), or contains structural unit one represented by formula (5) and structural unit three represented by formula (7), or contains structural unit two represented by formula (6) and structural unit three represented by formula (7). In formula (5), R4 is a hydrogen atom or a C1-C3 alkyl group. In formula (6), R5 is a hydrogen atom or a C1-C3 alkyl group, and R6 is an acid-labile group. In formula (7), R7 is a hydrogen atom or a C1-C3 alkyl group, and R8 is an acid-labile group. Specific examples of the C1-C3 alkyl group include, but are not limited to, any of a methyl group, an ethyl group, a n-propyl group, and an i-propyl group.

[0038] Formula (5), Formula (6), Formula (7).

[0039] In the present application, when the polymer resin contains structural unit one represented by formula (5) and structural unit two represented by formula (6), the molar ratio of the structural unit one to the structural unit two is preferably (1-3):1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or any ratio therebetween. When the polymer resin contains structural unit one represented by formula (5) and structural unit three represented by formula (7), the molar ratio of the structural unit one to the structural unit three is preferably (1-3):1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or any ratio therebetween. When the polymer resin contains structural unit two represented by formula (6) and structural unit three represented by formula (7), the molar ratio of the structural unit two to the structural unit three is preferably (0.5-1.5):1, such as 0.5:1, 1.5:1, 1.0:1, 1.2:1, 1.5:1, or any ratio therebetween.

[0040] In the present application, the weight average molecular weight (Mw) of the polymer resin is preferably 6000-20000 Da, such as 6000 Da, 8000 Da, 10000 Da, 12000 Da, 15000 Da, 18000 Da, 20000 Da, or any value therebetween; and the PDI is preferably 1.5-2.5, such as 1.5, 1.8, 2.0, 2.2, 2.5, or any value therebetween.

[0041] In the present application, the acid-labile group is a group that can be decomposed under acidic conditions for the purpose of deprotection, and can be selected from at least one of the following structures:

[0042]

[0043] .

[0044] In the present application, the acid diffusion inhibitor can be an amine compound, specific examples of which include, but are not limited to, at least one of the following: single alkyl amines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, etc.; dialkyl amines such as di-n-butylamine, di-n-pentylamine, di-n-hexylamine, di-n-heptylamine, di-n-octylamine, di-n-nonylamine, di-n-decylamine, etc.; trialkyl amines such as triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, etc.; aromatic amines such as aniline, N-methylaniline, N,N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, diphenylamine, triphenylamine, 1-naphthylamine, 2-(4-aminophenyl)-2-(3-hydroxyphenyl)propane, 2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, etc.

[0045] In the present application, the second organic solvent can be any one of the organic solvents used in the existing photoresist compositions, specific examples of which include, but are not limited to, at least one of the following: propylene glycol methyl ether, ethyl lactate, butyl acetate, propylene glycol methyl ether acetate, propylene glycol dimethyl ether, ethylene glycol monomethyl ether, cyclohexanone, methyl isopropyl ketone, cyclopentanone, ethanol, acetonitrile, isopropyl alcohol, acetone, etc.

[0046] The present application will be described in detail below through specific examples. The examples are intended to explain the present application and should not be construed as limiting the present application. If a specific technique or condition is not specified in the examples, the technique or condition described in the literature in the art or according to the product manual is used. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be commercially available.

[0047] Synthesis of thionyl salt type photoacid generator S1 This synthesis example is used to illustrate the preparation process of a thionyl salt type photoacid generator, the specific process and the synthetic route are as follows: Under the protection of argon, 9-ethynyl-9-thioxanthanol (1.0 mmol, 254.30 mg) and anhydrous tetrahydrofuran (THF) 10 mL were added to a reaction bottle, the reaction bottle was cooled in an ice water bath, potassium hydride (1.2 mmol, 48.00 mg) was added to the reaction solution in small portions, the reaction mixture was first stirred at 0°C for 30 min, then the temperature was raised to room temperature (25°C) and the reaction was continued for 1 h, obtaining a THF solution of 9-ethynyl-9H-thioxanth-9-ol potassium salt, denoted as intermediate product M1.

[0048] Another dry Schlenk tube, under argon protection, triphenylsulfonium chloride (1.5 mmol, 448.20 mg) was dissolved in 10 mL of anhydrous THF, the above-mentioned intermediate M1 solution was cooled to 0°C, and the THF solution of triphenylsulfonium chloride was slowly added dropwise to the intermediate M1 solution. After the addition was completed, the reaction was raised to room temperature, and stirred at room temperature (25°C) for 18 h. The mixture after the reaction was completed was transferred to a separatory funnel, extracted with 30 mL of dichloromethane, dried with anhydrous Na2SO4, filtered to remove the drying agent, and the filtrate was concentrated under reduced pressure using a rotary evaporator. The obtained crude product was purified using silica gel column chromatography to obtain a sulfonium salt type photoacid generator having the structure shown below, denoted as S1.

[0049]

[0050] Synthesis of sulfonium salt type photoacid generator S2 This synthesis example is used to illustrate the preparation process of a sulfonium salt type photoacid generator, the specific process and synthesis route are as follows: The sulfonium salt type photoacid generator was prepared according to the method of synthesis example 1, except that the same molar amount of 4-tert-butylphenyl-diphenylsulfonium chloride (1.5 mmol, 532.40 mg) was used instead of triphenylsulfonium chloride (1.5 mmol, 448.20 mg), and the other conditions were the same as in synthesis example 1. Thus, a sulfonium salt type photoacid generator having the structure shown below, denoted as S2, was obtained.

[0051]

[0052] Synthesis of sulfonium salt type photoacid generator S3 This synthesis example is used to illustrate the preparation process of a sulfonium salt type photoacid generator, the specific process and synthesis route are as follows: The sulfonium salt type photoacid generator was prepared according to the method of synthesis example 1, except that the same molar amount of triphenylsulfonium chloride (1.5 mmol, 448.20 mg) was used instead of triphenylsulfonium chloride (1.5 mmol, 448.20 mg), and the other conditions were the same as in synthesis example 1. Thus, a sulfonium salt type photoacid generator having the structure shown below, denoted as S2, was obtained.

[0053]

[0054] Synthesis of sulfonium salt type photoacid generator S4 This synthesis example is used to illustrate the preparation process of a sulfonium salt type photoacid generator, the specific process and synthesis route are as follows: The sulfonium salt type photoacid generator was prepared according to the method of synthesis example 1, except that the same molar amount of (4-cyclohexylphenyl) diphenyl sulfonium bromide (1.5 mmol, 638.14 mg) was used instead of triphenylsulfonium chloride (1.5 mmol, 448.20 mg), and the other conditions were the same as those of synthesis example 1, thereby obtaining the sulfonium salt type photoacid generator with the structure shown below, which is denoted as S4.

[0055]

[0056] Comparative synthesis example 1 reference sulfonium salt type photoacid generator DS1 The reference sulfonium salt type photoacid generator was prepared according to the method of synthesis example 1, except that the same molar amount of 9-hydroxythioxanthene (1.0 mmol, 214.28 mg) was used instead of 9-ethynyl-9-thioxanthanol (1.0 mmol, 254.30 mg), and the other conditions were the same as those of synthesis example 1, thereby obtaining the reference sulfonium salt type photoacid generator with the structure shown below, which is denoted as DS1.

[0057]

[0058] Preparation example 1 preparation of polymer resin P1 This preparation example is used to illustrate the preparation process of a polymer resin, and the specific process is as follows: At room temperature, t-butoxy styrene 7.93 g (45 mmol), p-hydroxystyrene 6.60 g (55 mmol) and initiator azobisisobutyronitrile 0.16 g (1 mmol) were sequentially added to 30 g of tetrahydrofuran solvent, and the reaction system was heated to 70°C under nitrogen atmosphere for 6 h. After cooling to room temperature, 500 g of methanol was added dropwise, and the polymer was precipitated by stirring, and then repeatedly washed with hexane, separated and dried to obtain the polymer resin P1 containing the structural units shown below and the molar content of each structural unit as shown below. It was detected that the Mw of the polymer resin P1 was 8900 Da and the PDI was 2.0.

[0059]

[0060] Preparation example 2 preparation of polymer resin P2 This preparation example is used to illustrate the preparation process of a polymer resin, and the specific process is as follows: Under the condition of room temperature, 1-methylcyclopentyl methyl acrylate 7.57 g (45 mmol), p-hydroxystyrene 6.60 g (55 mmol) and initiator azobisisobutyronitrile 0.16 g (1 mmol) are sequentially added into 30 g of tetrahydrofuran solvent, the reaction system is heated to 70 ℃ under nitrogen atmosphere for 6 h, after cooling to room temperature, 500 g of methanol is added dropwise, the polymer is precipitated by stirring, and then separated, dried after repeatedly washing with hexane, the obtained polymer resin P2 contains the following structural units and the molar content of each structural unit is as follows. It is detected that the Mw of the polymer resin P2 is 10500 Da, and the PDI is 1.8.

[0061]

[0062] Preparation of polymer resin P3 This preparation example is used to illustrate the preparation process of a polymer resin, and the specific process is as follows: Under the condition of room temperature, 5.10 g (30 mmol) of 2-carbonyl-tetrahydrofuran-3-hydroxyl-methyl acrylate, p-hydroxystyrene 8.41 g (70 mmol) and initiator azobisisobutyronitrile 0.16 g (1 mmol) are sequentially added into 30 g of tetrahydrofuran solvent, the reaction system is heated to 70 ℃ under nitrogen atmosphere for 6 h, after cooling to room temperature, 500 g of methanol is added dropwise, the polymer is precipitated by stirring, and then separated, dried after repeatedly washing with hexane, the obtained polymer resin P3 contains the following structural units and the molar content of each structural unit is as follows. It is detected that the Mw of the polymer resin P3 is 15600 Da, and the PDI is 2.2.

[0063]

[0064] Preparation of polymer resin P4 This preparation example is used to illustrate the preparation process of a polymer resin, and the specific process is as follows: Under the condition of room temperature, 5.47 g (35 mmol) of 2-tetrahydrofuryl methyl acrylate, p-hydroxystyrene 7.80 g (65 mmol) and initiator azobisisobutyronitrile 0.16 g (1 mmol) are sequentially added into 30 g of tetrahydrofuran solvent, the reaction system is heated to 70 ℃ under nitrogen atmosphere for 6 h, after cooling to room temperature, 500 g of methanol is added dropwise, the polymer is precipitated by stirring, and then separated, dried after repeatedly washing with hexane, the obtained polymer resin P4 contains the following structural units and the molar content of each structural unit is as follows. It is detected that the Mw of the polymer resin P4 is 13000 Da, and the PDI is 1.75.

[0065]

[0066] Preparation of polymer resin P5 This preparation example is used to illustrate the preparation process of a polymer resin, the specific process is as follows: At room temperature, 1-methylcyclopentyl methacrylate 7.57 g (45 mmol), tert-butoxy styrene 9.69 g (55 mmol) and initiator azobisisobutyronitrile 0.16 g (1 mmol) were sequentially added to 30 g of tetrahydrofuran solvent, and the 2-carbonyl-tetrahydrofuran-3-hydroxyl-methacrylate reaction system was heated to 70°C under nitrogen atmosphere for 6h, and then cooled to room temperature. 500 g of methanol was added dropwise, and the polymer was precipitated by stirring. After repeated washing with hexane, the polymer was separated and dried to obtain the polymer resin P5 containing the structural units shown below and the molar content of each structural unit as shown below. The Mw of the polymer resin P5 was 87500 Da, and the PDI was 1.8.

[0067]

[0068] Examples 1-7 and Comparative Examples 1-2 100 parts by weight of the polymer resin, 6 parts by weight of the photoacid generator, 1 part by weight of the acid diffusion inhibitor, and 2000 parts by weight of propylene glycol methyl ether acetate (PGMEA) were weighed and mixed and stirred to dissolve. The resulting dissolved product was filtered with a filter having a pore size of 0.5 μm to obtain a photoresist composition. The specific types of the polymer resin and the photoacid generator are shown in Table 1.

[0069] Table 1

[0070] Test Example The photoresist compositions prepared in the above examples and comparative examples were used to form a photoetching pattern and evaluate the sensitivity, LER, CDU and thermal stability according to the following method, and the results are shown in Table 2.

[0071] (1) Formation method of photoresist pattern: The photoresist compositions prepared in the above examples and comparative examples were spin-coated onto a substrate, respectively, and baked on a hot plate at 110°C for 60 seconds to form a photoresist film having a thickness of 0.10 μm. Exposure was performed using a Nikon KrF excimer laser exposure system (numerical aperture 0.8). Thereafter, baking was performed at 90°C for 60 seconds, and then development was performed at 23°C for 4 seconds using a 2.38 wt% aqueous solution of tetramethylammonium hydroxide (TMAH developer), followed by water washing and drying to form a positive resist photoresist pattern. The pattern formed after development was observed by scanning electron microscopy CDSEM (CG6300).

[0072] (2) Sensitivity test: The exposure amount for forming a line-and-space pattern (1L / 1S) having a line width of 100 nm and a line width of 1:1 was defined as the optimum exposure amount, and the optimum exposure amount was defined as the sensitivity. The smaller the optimum exposure amount, the higher the sensitivity.

[0073] (3) LWR test: When the 100 nm 1L / 1S pattern resolved at the optimum exposure dose was observed from the top of the pattern using CDSEM (CG6300), the line width was observed at any 10 points, and the standard deviation (σ) was calculated from the results, and 3σ was used as the measurement value of LWR. The smaller the value, the better the linearity of the pattern after development.

[0074] (4) CDU test: The linear pattern formed by the above method was observed under CDSEM, and the width of 100 lines was tested at different test points, and the average line width value of each test point line was calculated, and the three times value (3σ) of the standard deviation (σ) was calculated, and the value was recorded as the critical dimension uniformity (CDU). The smaller the value, the better the size uniformity of the pattern, and the higher the process stability.

[0075] (5) Thermal stability test: The photoresist compositions prepared in the above examples and comparative examples were coated on silicon wafer using a spin coater, and the photoresist film was formed by heat treatment at 110°C for 1 minute; the photoresist film was scraped from the silicon wafer, and the powder obtained was tested by thermogravimetric analysis (TGA) under nitrogen atmosphere from 30°C to 400°C, and the initial mass and the mass at 400°C of each powder were recorded, and the mass loss rate was calculated by the formula: mass loss rate = (initial mass - mass at 400°C) / initial mass x 100%.

[0076] Table 2

[0077] As can be seen from the results of Table 1, the photoresist compositions provided by Examples 1 to 7 exhibit significantly improved sensitivity, critical dimension uniformity (CDU) and thermal stability and reduced line width roughness (LER) due to the use of the specific structure of the sulfonium salt type photoacid generator, compared to Comparative Examples 1 to 2.

[0078] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary, and should not be construed as limiting the present application, and those ordinarily skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments without departing from the principles and spirit of the present application within the scope of the present application.

Claims

1. A sulfonium salt type photo-acid generator characterized by, having a structure represented by formula (1): formula (1), In formula (1), R1, R2, R3are each independently selected from C1-C12 alkyl, C1-C12 alkoxy or C3-C20 cycloalkyl, and a, b, c are each independently an integer of 0-5.

2. The method for producing a sulfonium salt photo-acid generator according to claim 1, characterized by, The preparation method comprises the following steps: S1. 9-ethynyl-9-thioxanthanol having a structure represented by formula (2) is subjected to a metallation reaction with an alkali metal hydride and a first organic solvent under an inert gas condition to obtain an intermediate product M1 represented by formula (3); S2. The intermediate product M1 is subjected to an ion exchange reaction with a compound M2 represented by formula (4), and the obtained reaction product is a sulfonium salt type photo-acid generator represented by formula (1); formula (2), formula (3), Equation (4), In formula (4), R1, R2, R3are each independently selected from C1-C12 alkyl, C1-C12 alkoxy, or C3-C20 cycloalkyl, a, b, c are each independently an integer of 0-5, X - is a halogen ion.

3. The method for producing a sulfonium salt photo-acid generator according to claim 2, characterized by, In step S1, the molar ratio of the 9-ethynyl-9-thioxanthanol to the alkali metal hydride is 1:(1.1-1.3); Preferably, the conditions of the metallation reaction include that the first reaction temperature is -5-5℃, and the first reaction time is 0.5-1.0h; and the second reaction temperature is 15-25℃, and the second reaction time is 0.5-2.0h.

4. The method for producing a sulfonium salt photo-acid generator according to claim 2, characterized by, In step S1, the alkali metal hydride is potassium hydride and / or sodium hydride; Preferably, the first organic solvent is at least one selected from tetrahydrofuran, N,N-dimethylformamide, diethyldimethyl ether and toluene.

5. The method for producing a sulfonium salt photo-acid generator according to claim 2, wherein In step S2, the molar ratio of the compound M2 to the intermediate product M1 is (1.3-1.8):1; Preferably, the conditions of the ion exchange reaction include that the temperature is 15-25℃, and the time is 12-24h.

6. A photoresist composition characterized by comprising: The photoresist composition comprises a polymer resin containing an acid-sensitive group, the sulfonium salt type photo-acid generator according to claim 1, an acid diffusion inhibitor and a second organic solvent.

7. The photoresist composition of claim 6, wherein The content of the polymer resin is 50-200 parts by weight, the content of the sulfonium salt type photo-acid generator is 1-30 parts by weight, the content of the acid diffusion inhibitor is 1-5 parts by weight, and the content of the second organic solvent is 1000-4000 parts by weight.

8. The photoresist composition of claim 6, wherein The polymer resin contains structural unit one represented by formula (5) and structural unit two represented by formula (6), or contains structural unit one represented by formula (5) and structural unit three represented by formula (7), or contains structural unit two represented by formula (6) and structural unit three represented by formula (7); Formula (5), Formula (6), Formula (7), In formula (5), R4is a hydrogen atom or C1-C3 alkyl; In formula (6), R5is a hydrogen atom or C1-C3 alkyl, and R6is an acid-labile group; In formula (7), R7is a hydrogen atom or C1-C3 alkyl, and R8is an acid-labile group; Preferably, when the polymer resin contains structural unit one represented by formula (5) and structural unit two represented by formula (6), the molar ratio of the structural unit one to the structural unit two is (1-3):1; Preferably, when the polymer resin contains structural unit one represented by formula (5) and structural unit three represented by formula (7), the molar ratio of the structural unit one to the structural unit three is (1-3):1; Preferably, when the polymer resin contains structural unit two represented by formula (6) and structural unit three represented by formula (7), the molar ratio of structural unit two to structural unit three is (0.5-1.5):

1.

9. The photoresist composition of claim 6, wherein The acid-labile group is selected from at least one of the following structures: 。 10. Use of the sulfonium salt type photo-acid generator according to claim 1 and / or the photoresist composition according to claims 6-9 in photolithography.

Images