Photoinduced acid generator, preparation method thereof and photoresist based on photoinduced acid generator

Abstract

The invention provides a photoacid generator, a preparation method thereof and a photoresist based on the photoacid generator. The photoacid generator is 4-alkyl-N-hydroxyl naphthalimide fluoroalkyl sulfonate, and the molecular structural formula of the photoacid generator is # imgabs 0 #, and in the formula, R is alkyl. The preparation method of the photoacid generator comprises the following steps: S1, dissolving 5-alkyl acenaphthene in a first solvent, heating, adding potassium permanganate in the heating process, then heating to reflux for reaction, and after the reaction is finished, purifying to obtain 4-alkyl-1, 8-naphthalic anhydride; s2, dissolving the 4-alkyl-1, 8-naphthalic anhydride, hydroxylamine hydrochloride and a first inorganic base in a second solvent for reaction, and after the reaction is finished, purifying to obtain 4-alkyl-N-hydroxy-1, 8-naphthalic imide; and S3, adding the 4-alkyl-N-hydroxy-1, 8-naphthalimide and an organic alkali into a third solvent, dropwise adding fluoroalkyl sulfonic anhydride, heating to react after dropwise adding is completed, and purifying after the reaction is completed to obtain the 4-alkyl-N-hydroxy-1, 8-naphthalimide. The photoresist based on the photoacid generator provided by the invention is large in ADR, and the negative photoresist development defect and the standing wave are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photolithographic materials, and in particular relates to a photoacid generator and a preparation method thereof, and a photoresist based on the photoacid generator. Background Art

[0002] Sulfonate derivative compounds with N-hydroxynaphthalimide functional groups are mainly used as cationic photoinitiators, non-ionic photoacid generators, etc., and are a widely used optical material. Photoacid generator is a special compound, which is the core component of chemically amplified photoresist system. When it is exposed to light of a specific wavelength, it can decompose to produce protons (H+) or other strong acidic substances. When a light source of a specific wavelength is used to irradiate a wafer coated with photoresist, the photoacid generator decomposes under the excitation of light to generate strong acid. The generated acid can catalyze subsequent chemical reactions. Specifically, after the acid catalysis of the photoresist in the exposed area, the cross-linking or solubility of the photoresist is promoted, so that the specific area can be dissolved by the developer during the development process, thereby realizing the transfer of the pattern.

[0003] However, the sulfonate derivative compounds of the N-hydroxynaphthaleneimide functional group of the photoacid generator in the prior art have poor solubility and obvious dissolution inhibition, resulting in a small ADR of the prepared photoresist, obvious negative resist development defects, and a standing wave effect. Summary of the invention

[0004] In order to solve the problems in the prior art, the present invention provides a photoacid generator and a preparation method thereof, and a photoresist based on the photoacid generator.

[0005] The specific technical solutions of the present invention are as follows:

[0006] The photoacid generator provided by the present invention is characterized in that the photoacid generator is 4-alkyl-N-hydroxynaphthalene imide fluoroalkyl sulfonate, and its molecular structure is: In the formula, R is an alkyl group.

[0007] The photoacid generator provided by the present invention also has the following technical feature, wherein the alkyl group is ethyl, propyl, butyl, pentyl or hexyl.

[0008] The present invention also provides a method for preparing the above-mentioned photoacid generator, characterized in that it comprises the following steps:

[0009] Step S1, dissolving 5-alkylacenaphthene in a first solvent, heating and heating, adding potassium permanganate during the heating process, and then heating to reflux for reaction, and after the reaction is completed, purifying to obtain 4-alkyl-1,8-naphthalene dicarboxylic anhydride;

[0010] Step S2: dissolving 4-alkyl-1,8-naphthalene dicarboxylic anhydride, hydroxylamine hydrochloride and the first inorganic base in a second solvent for reaction, and after the reaction is completed, purifying to obtain 4-alkyl-N-hydroxy-1,8-naphthalene dicarboximide;

[0011] Step S3: adding 4-alkyl-N-hydroxy-1,8-naphthalene diimide and an organic base to a third solvent, and dropping fluoroalkylsulfonic anhydride. After the dropping is completed, heating is carried out to react. After the reaction is completed, purification is performed to obtain 4-alkyl-N-hydroxynaphthalene imide fluoroalkylsulfonic acid ester, i.e., a photoacid generator.

[0012] The method for preparing the photoacid generator provided by the present invention is characterized in that it also includes at least one of the following technical features:

[0013] a1) in step S1, the 5-alkylacenaphthene is 5-ethylacenaphthene, 5-propylacenaphthene, 5-butylacenaphthene, 5-pentylacenaphthene or 5-hexylacenaphthene;

[0014] a2) in step S1, the first solvent is acetic acid;

[0015] a3) in step S1, the molar ratio of 5-alkylacenaphthene to potassium permanganate is 1:1.2 to 1:2.5;

[0016] a4) In step S1, the purification process is as follows: adding dichloromethane to the reaction solution, filtering, washing the filter cake with dichloromethane, combining the filtrate, washing with water, washing with saturated sodium bicarbonate water, drying the organic phase, concentrating, adding methyl tert-butyl ether for pulping, filtering, and drying;

[0017] a5) in step S2, the first inorganic base is sodium bicarbonate;

[0018] a6) in step S2, the second solvent is N,N-dimethylformamide;

[0019] a7) In step S2, the reaction temperature is 40-50°C;

[0020] a8) in step S2, the molar ratio of 4-alkyl-1,8-naphthalene dicarboxylic anhydride, hydroxylamine hydrochloride and the first inorganic base is 1:1:1 to 1:2:2;

[0021] a9) In step S2, the purification process is as follows: pouring the reaction solution into ice water, filtering, drying, beating with methanol, filtering, and drying;

[0022] a10) in step S3, the organic base is pyridine;

[0023] a11) in step S3, the third solvent is dichloromethane;

[0024] a12) in step S3, the fluoroalkylsulfonic anhydride is trifluoromethanesulfonic anhydride or nonafluorobutylsulfonic anhydride;

[0025] a13) in step S3, the molar ratio of 4-alkyl-N-hydroxy-1,8-naphthalimide, the organic base and the fluoroalkylsulfonic anhydride is 1:1:1 to 1:2:2;

[0026] a14) in step S3, the temperature for adding fluoroalkylsulfonic anhydride dropwise is 0-5°C;

[0027] a15) in step S3, the reaction temperature for heating the reaction is room temperature;

[0028] a16) In step S3, the purification process is as follows: adding water to the reaction solution, separating the liquids, washing the organic phase with water, washing with saturated sodium bicarbonate water, concentrating, and drying.

[0029] The preparation method of the photoacid generator provided by the present invention also has the following technical features: the preparation method of 5-alkylacenaphthene in step S1 comprises the following steps:

[0030] Step S1-1, dissolving acenaphthene in a fourth solvent, adding dropwise a solution prepared by N-bromosuccinimide and the fourth solvent to carry out a bromination reaction, and after the reaction is completed, purifying to obtain 5-bromoacenaphthene;

[0031] Step S1-2, dissolving 5-bromoacenaphthene, alkylboric acid, a second inorganic base and a phase transfer catalyst in a fifth solvent and water, adding a palladium catalyst, heating to reflux for reaction, and after the reaction is completed, purifying to obtain 5-alkylacenaphthene.

[0032] The method for preparing the photoacid generator provided by the present invention is characterized in that it also includes at least one of the following technical features:

[0033] b1) in step S1-1, the fourth solvent is N,N-dimethylformamide;

[0034] b2) in step S1-1, the temperature of the bromination reaction is room temperature;

[0035] b3) in step S1-1, the molar ratio of acenaphthene to N-bromosuccinimide is 1:1 to 1:2;

[0036] b4) In step S1-1, the purification process is as follows: pouring the reaction solution into ice water, filtering, washing the filter cake with water, adding the filter cake into methanol for recrystallization, cooling to 0-10°C, filtering, and draining the filter cake;

[0037] b5) in step S1-2, the alkyl boronic acid is ethyl boronic acid, propyl boronic acid, butyl boronic acid, pentyl boronic acid or hexyl boronic acid;

[0038] b6) In step S1-2, the second inorganic base is potassium carbonate;

[0039] b7) in step S1-2, the phase transfer catalyst is tetramethylammonium chloride, 18-crown-6 or tetrabutylammonium chloride;

[0040] b8) In step S1-2, the fifth solvent is toluene;

[0041] b9) in step S1-2, the palladium catalyst is PdCl2(dppf);

[0042] b10) In step S1-2, the molar ratio of 5-bromoacenaphthene, alkylboric acid and the second inorganic base is 1:1.5:1.5 to 1:2:3;

[0043] b11) In step S1-2, the purification process is as follows: separating the reaction solution, concentrating the organic phase to dryness, dissolving it in petroleum ether, filtering it with silica gel, concentrating the filtrate, adding methanol to pulp, filtering, and drying it.

[0044] The present invention also provides a photoresist comprising the photoacid generator.

[0045] The photoresist provided by the present invention also has the following technical features: the photoresist also includes a polymer resin, a cross-linking agent, an acid diffusion inhibitor, an additive and a solvent.

[0046] The photoresist provided by the present invention also has such a technical feature that the photoresist comprises the following components in percentage by mass:

[0047] Polymer resin 5-15%,

[0048] Photoacid generator 0.1~0.5%,

[0049] Crosslinking agent 0.6~1.0%,

[0050] Acid diffusion inhibitor 0.01~0.05%,

[0051] Additives 0.005~0.015%,

[0052] Solvent Residue.

[0053] The photoresist provided by the present invention also includes at least one of the following technical features:

[0054] c1) The molecular structure formula of the polymer resin is: Wherein x=60~95, y=5~40;

[0055] c2) The molecular structural formula of the cross-linking agent is:

[0056] c3) the acid diffusion inhibitor is triethanolamine;

[0057] c4) the additive is a fluorocarbon surfactant;

[0058] c5) The solvent is propylene glycol methyl ether acetate (PGMEA).

[0059] Functions and Effects of the Invention

[0060] Compared with the prior art, the technical advantages of the present invention are as follows:

[0061] The photoacid generator provided by the invention has good solubility and no dissolution inhibition effect, so the photoresist prepared by the photoacid generator has a large ADR, and the negative resist development defects and standing waves are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is the HNMR spectrum of 5-bromoacenaphthene prepared in Example 1 of the present invention.

[0063] Figure 2 This is the HNMR spectrum of 5-butylacenaphthene prepared in Example 1 of the present invention.

[0064] Figure 3 It is the HNMR spectrum of 4-butyl-1,8-naphthalene dicarboxylic anhydride prepared in Example 1 of the present invention.

[0065] Figure 4 It is the HNMR spectrum of 4-butyl-N-hydroxynaphthalimide trifluorosulfonate prepared in Example 1 of the present invention.

[0066] Figure 5 It is the photolithography pattern of Example 2 of the present invention.

[0067] Figure 6 It is a photolithography pattern of a comparative example of the present invention. DETAILED DESCRIPTION

[0068] The terms used in the present invention, unless otherwise specified, generally have the meanings that are commonly understood by those of ordinary skill in the art.

[0069] In the following examples, various processes and methods not described in detail are conventional methods well known in the art.

[0070] The reagents used in the following examples were purchased from common commercial sources, and the experimental operations and experimental conditions not specified were referred to the conventional operations and conventional conditions in the art.

[0071] The specific implementation of the present invention is described below in conjunction with embodiments and drawings.

[0072] <Example 1>

[0073] This embodiment provides a photoacid generator and a preparation method thereof. The photoacid generator is 4-butyl-N-hydroxynaphthalimide trifluorosulfonate, and its molecular structure is:

[0074] The preparation method of the above-mentioned photoacid generator is as follows:

[0075] Step S1, dissolving 5-alkylacenaphthene in a first solvent, heating and heating the solvent, adding potassium permanganate during the heating process, and then heating the solvent to reflux for reaction. After the reaction is completed, purifying the solvent to obtain 4-alkyl-1,8-naphthalene dicarboxylic anhydride.

[0076] The specific process is:

[0077] 5-Butylacenaphthene (100.00 g, 0.47 mol) and acetic acid (1 L, the first solvent) were added to a 2 L four-necked bottle, mechanically stirred and dissolved, and the temperature was gradually raised from room temperature to reflux. Potassium permanganate (74 g, 0.94 mol) was added in batches during the heating process. After the addition, the reaction was stirred under reflux for 20 hours. After the reaction was completed, the temperature was lowered to room temperature, 1 L of dichloromethane was added, filtered, the filter cake was washed with dichloromethane, the filtrate was combined, washed once with water, washed once with saturated sodium bicarbonate water, the organic phase was dried, concentrated, methyl tert-butyl ether was added for pulping, filtered, and dried to obtain 4-butyl-1,8-naphthalene dicarboxylic anhydride (solid, 98 g), with a molar yield of 81.67%.

[0078] Figure 3 It is the HNMR spectrum of 4-butyl-1,8-naphthalene dicarboxylic anhydride prepared in Example 1 of the present invention.

[0079] HNMR spectrum analysis:

[0080] 1H NMR(400MHz,Chloroform-d)δ8.74–8.59(m,1H),8.59–8.40(m,2H),7.83(dd,J=8.5,7.3Hz,1 H),7.65(d,J=7.5Hz,1H),3.31–3.09(m,2H),1.87–1.66(m,2H),1.48(dt,J=14.7,7.4Hz,2H).

[0081] The molecular structure of 4-butyl-1,8-naphthalene dicarboxylic anhydride is:

[0082] Wherein, the preparation method of 5-butylacenaphthene is:

[0083] Step S1-1, dissolving acenaphthene in a fourth solvent, adding dropwise a solution prepared by N-bromosuccinimide and the fourth solvent, and performing a bromination reaction. After the reaction is completed, 5-bromoacenaphthene is purified. The specific process is:

[0084] Add acenaphthene (10.00 g, 64.8 mmol) and N,N-dimethylformamide (50 mL, fourth solvent) to a 250 mL reaction bottle, stir at room temperature to dissolve. Prepare a solution of N-bromosuccinimide (13.84 g, 77.8 mmol) and N,N-dimethylformamide (50 mL, fourth solvent), then add dropwise to the reaction system, controlling the internal temperature not to exceed 30°C. After the addition is complete, stir and react at room temperature for 6 hours. After the reaction is completed, pour the reaction solution into 300 mL of ice water, filter, wash the filter cake with water 3 times, add 2 times the volume of methanol for recrystallization, cool to 0-10°C for filtration, and drain the filter cake to obtain 5-bromoacenaphthene (brown solid, 15 g), with a molar yield of 98.8%.

[0085] Figure 1 It is the HNMR spectrum of 5-bromoacenaphthene prepared in Example 1 of the present invention.

[0086] HNMR spectrum analysis:

[0087] 1H NMR(400MHz,Chloroform-d)δ7.75(d,J=8.3Hz,1H),7.64(d,J=7.3Hz,1H),7.53(dd,J=8.4,6.9Hz,1H), 7.30(d,J=6.8Hz,1H),7.11(dt,J=7.3,1.5Hz,1H),3.39(ddd,J=7.0,4.1,1.4Hz,2H),3.35–3.27(m,2H).

[0088] The molecular structure of 5-bromoacenaphthene is:

[0089] Step S1-2, dissolving 5-bromoacenaphthene, alkylboric acid, a second inorganic base and a phase transfer catalyst in a fifth solvent and water, adding a palladium catalyst, heating to reflux for reaction, and purifying to obtain 5-alkylacenaphthene after the reaction is completed. The specific process is:

[0090] 5-bromoacenaphthene (100.00 g, 0.429 mol), n-butylboric acid (65.60 g, 0.643 mol), potassium carbonate (148.23 g, 1.072 mol, second inorganic base), toluene (500 mL, fifth solvent), water (500 mL) and phase transfer catalyst tetramethylammonium chloride were added to a 2L reaction bottle, and PdCl2 (dppf) (palladium catalyst) was added after argon replacement, and then heated to reflux reaction for 20 h. After the reaction was completed, it was cooled to room temperature, separated, the organic phase was concentrated to dryness, dissolved in 500 mL of petroleum ether, filtered with silica gel, the filtrate was concentrated, 200 mL of methanol was added for pulping, filtered, and dried to obtain 5-butylacenaphthene (light yellow solid, 81.3 g), with a molar yield of 90.4%.

[0091] Figure 2 This is the HNMR spectrum of 5-butylacenaphthene prepared in Example 1 of the present invention.

[0092] HNMR spectrum analysis:

[0093] 1H NMR(400MHz,Chloroform-d)δ7.70(d,J=8.3Hz,1H),7.44(dd,J=8.4,6.8Hz,1H),7.30–7.22(m,2H),7.19(dt,J=6.9,1.4Hz, 1H),3.37(tq,J=9.1,4.5Hz,4H),3.13–2.84(m,2H),1.85–1.60(m,2H),1.43(dt,J=14.7,7.4Hz,2H),0.96(t,J=7.3Hz,3H).

[0094] The molecular structure of 5-butylacenaphthene is:

[0095] Step S2: Dissolve 4-alkyl-1,8-naphthalene dicarboxylic acid, hydroxylamine hydrochloride and the first inorganic base in the second solvent for reaction, and purify to obtain 4-alkyl-N-hydroxy-1,8-naphthalene dicarboxylic acid after the reaction is completed. The specific process is:

[0096] 4-Butyl-1,8-naphthalene dicarboxylic anhydride (34 g, 0.134 mol), hydroxylamine hydrochloride (11.1 g, 0.160 mol), sodium bicarbonate (13.5 g, 0.160 mol, first inorganic base) and N,N-dimethylformamide (200 mL, second solvent) were added to a 500 mL reaction bottle, stirred magnetically, and heated to 45 ° C for 1 h. After the reaction was completed, the temperature was cooled to room temperature, poured into 500 mL of ice water, filtered, dried, slurried with 100 mL of methanol, filtered, and dried to obtain 4-butyl-N-hydroxy-1,8-naphthalene dicarboximide (off-white solid, 33 g), with a molar yield of 91.67%.

[0097] The molecular structure of 4-butyl-N-hydroxy-1,8-naphthalimide is:

[0098] Step S3: Add 4-alkyl-N-hydroxy-1,8-naphthalene dicarboximide and an organic base to the third solvent, add fluoroalkylsulfonic anhydride dropwise, and heat to react after the addition is complete. After the reaction is complete, purify to obtain 4-alkyl-N-hydroxynaphthalene imide fluoroalkylsulfonic acid ester, i.e., photoacid generator. The specific process is:

[0099] Add 4-butyl-N-hydroxy-1,8-naphthalimide (30.00 g, 0.111 mol), pyridine (14.1 g, 0.178 mol, organic base) and dichloromethane (300 mL, third solvent) to a 500 mL reaction bottle, cool to 0-5 ° C, add trifluoromethanesulfonic anhydride (40.8 g, 0.145 mol), add dropwise, warm to room temperature and react for 1 hour. Take a sample of TLC control (control 1), the raw material is basically reacted, add 200 mL of water, separate the liquid, wash the organic phase with water once, wash with saturated sodium bicarbonate once, concentrate, and dry to obtain 4-butyl-N-hydroxynaphthalimide trifluorosulfonate (off-white solid, 40 g), the molar yield is 89.48%, and the sampling HPLC purity is HPLC>99%.

[0100] Figure 4 It is the HNMR spectrum of 4-butyl-N-hydroxynaphthalimide trifluorosulfonate prepared in Example 1 of the present invention.

[0101] HNMR spectrum analysis:

[0102] 1H NMR(400MHz,Chloroform-d)δ8.67(ddt,J=6.7,4.5,1.1Hz,1H),8.63–8.55(m,1H),8.53(dt,J=8.5,1.2Hz,1H),7.84(ddd,J=8.7,7. 2,1.6Hz,1H),7.67(dd,J=7.6,1.6Hz,1H),3.30–3.14(m,2H),1.85–1.69(m,2H),1.48(dt,J=14.8,7.4Hz,2H),1.00(t,J=7.3Hz,3H).

[0103] The molecular structure of 4-butyl-N-hydroxynaphthaleneimide trifluorosulfonate is:

[0104]

[0105] <Example 2>

[0106] This embodiment provides a photoresist, and the components of the photoresist are listed in Table 1.

[0107] Table 1

[0108]

[0109]

[0110] Note: In Table 1, the molecular structure formula of polymer resin A is: Wherein x=95, y=5; the molecular structure of crosslinking agent B is:

[0111] The above components are mixed evenly, and filtered through three PTFE membranes of 0.45 μm + 0.05 μm + 0.05 μm to obtain a photoresist.

[0112] The prepared photoresist was spin-coated at 1000-3000 rpm on an 8-inch bare silicon wafer provided with a HDMS primer to form a 9000 Å film. Pre-baked on a 90°C hot plate for 60 seconds, then selectively exposed (450nm Line / Space) using a KrF exposure machine S204 (Conventional: NA0.55Sigma 0.6), then post-baked on a 120°C hot plate for 60 seconds, and after the wafer was cooled to room temperature, developed with a 2.38% TMAH developer for 60 seconds, and finally rinsed with deionized water for 30 seconds to form a photolithography pattern, as shown in FIG. Figure 5 shown.

[0113] <Comparative Example>

[0114] In this comparative example, the photoresist is prepared using triphenylsulfur trifluoromethanesulfonate (TPS-TF), a photoacid generator in the prior art. The components of the photoresist are the same, and the amounts used are also the same, except that the photoacid generator (4-butyl-N-hydroxynaphthalimide trifluorosulfonate) in Example 2 is replaced by TPS-TF.

[0115] The photoresist prepared in this comparative example is used according to the method for using the photoresist in Example 2 to form a photolithographic pattern such as Figure 6 shown.

[0116] Depend on Figure 5 , 6 By comparison, it can be seen that compared with the photoacid generator triphenylsulfur trifluoromethanesulfonate in the prior art, the photoresist prepared using the photoacid generator 4-butyl-N-hydroxynaphthalimide trifluorosulfonate provided by the present invention has a larger ADR, and no negative resist development defects and standing wave effect are observed.

[0117] The above is a detailed description of the embodiments, which is convenient for those skilled in the art to correctly understand and use the present invention. Any improvements or modifications to the technical solutions obtained by those skilled in the art based on the present invention on the basis of the prior art, without innovative work, only through analysis, analogy or limited enumeration, etc., should be within the scope of protection determined by the claims.

Claims

1. A photoacid generator, characterized in that: The photoacid generator is 4-alkyl-N-hydroxynaphthalene imide fluoroalkyl sulfonate, and its molecular structure is: In the formula, R is an alkyl group.

2. The photoacid generator according to claim 1, characterized in that in, The alkyl group is ethyl, propyl, butyl, pentyl or hexyl.

3. A method for preparing a photoacid generator as claimed in claim 1 or 2, characterized in that: The steps include: Step S1, dissolving 5-alkylacenaphthene in a first solvent, heating and heating, adding potassium permanganate during the heating process, and then heating to reflux for reaction, and after the reaction is completed, purifying to obtain 4-alkyl-1,8-naphthalene dicarboxylic anhydride; Step S2: dissolving the 4-alkyl-1,8-naphthalene dicarboxylic anhydride, hydroxylamine hydrochloride and the first inorganic base in a second solvent for reaction, and after the reaction is completed, purifying to obtain 4-alkyl-N-hydroxy-1,8-naphthalene dicarboximide; Step S3: adding the 4-alkyl-N-hydroxy-1,8-naphthalimide and an organic base to a third solvent, adding fluoroalkylsulfonic anhydride dropwise, heating to react after the addition is complete, and purifying to obtain 4-alkyl-N-hydroxynaphthalimide fluoroalkylsulfonate, i.e., the photoacid generator.

4. The method for preparing the photoacid generator according to claim 3, characterized in that: It also includes at least one of the following technical features: a1) in step S1, the 5-alkylacenaphthene is 5-ethylacenaphthene, 5-propylacenaphthene, 5-butylacenaphthene, 5-pentylacenaphthene or 5-hexylacenaphthene; a2) in step S1, the first solvent is acetic acid; a3) in step S1, the molar ratio of the 5-alkylacenaphthene to the potassium permanganate is 1:1.2 to 1:2.5; a4) In step S1, the purification process is as follows: adding dichloromethane to the reaction solution, filtering, washing the filter cake with dichloromethane, combining the filtrate, washing with water, washing with saturated sodium bicarbonate water, drying the organic phase, concentrating, adding methyl tert-butyl ether for pulping, filtering, and drying; a5) in step S2, the first inorganic base is sodium bicarbonate; a6) in step S2, the second solvent is N,N-dimethylformamide; a7) In step S2, the reaction temperature is 40-50°C; a8) in step S2, the molar ratio of the 4-alkyl-1,8-naphthalene dicarboxylic anhydride, the hydroxylamine hydrochloride and the first inorganic base is 1:1:1 to 1:2:2; a9) In step S2, the purification process is: pouring the reaction solution into ice water, filtering, drying, beating with methanol, filtering, and drying; a10) in step S3, the organic base is pyridine; a11) in step S3, the third solvent is dichloromethane; a12) in step S3, the fluoroalkylsulfonic anhydride is trifluoromethanesulfonic anhydride or nonafluorobutylsulfonic anhydride; a13) in step S3, the molar ratio of the 4-alkyl-N-hydroxy-1,8-naphthalimide, the organic base and the fluoroalkylsulfonic anhydride is 1:1:1 to 1:2:2; a14) in step S3, the temperature of adding fluoroalkylsulfonic anhydride dropwise is 0-5°C; a15) in step S3, the reaction temperature for the heating reaction is room temperature; a16) In step S3, the purification process is: adding water to the reaction solution, separating the liquids, washing the organic phase with water, washing with saturated sodium bicarbonate water, concentrating, and drying.

5. The method for preparing the photoacid generator according to claim 3, characterized in that: The preparation method of 5-alkylacenaphthene in step S1 comprises the following steps: Step S1-1, dissolving acenaphthene in a fourth solvent, adding dropwise a solution prepared by N-bromosuccinimide and the fourth solvent to carry out a bromination reaction, and after the reaction is completed, purifying to obtain 5-bromoacenaphthene; Step S1-2, dissolving the 5-bromoacenaphthene, alkylboric acid, a second inorganic base and a phase transfer catalyst in a fifth solvent and water, adding a palladium catalyst, heating to reflux for reaction, and after the reaction is completed, purifying to obtain the 5-alkylacenaphthene.

6. The method for preparing a photoacid generator according to claim 5, characterized in that: It also includes at least one of the following technical features: b1) in step S1-1, the fourth solvent is N,N-dimethylformamide; b2) in step S1-1, the temperature of the bromination reaction is room temperature; b3) In step S1-1, the molar ratio of the acenaphthene to the N-bromosuccinimide is 1:1 to 1:2; b4) In step S1-1, the purification process is as follows: pouring the reaction solution into ice water, filtering, washing the filter cake with water, adding the filter cake into methanol for recrystallization, cooling to 0-10°C, filtering, and draining the filter cake; b5) in step S1-2, the alkyl boronic acid is ethyl boronic acid, propyl boronic acid, butyl boronic acid, pentyl boronic acid or hexyl boronic acid; b6) In step S1-2, the second inorganic base is potassium carbonate; b7) In step S1-2, the phase transfer catalyst is tetramethylammonium chloride, 18-crown-6 or tetrabutylammonium chloride; b8) In step S1-2, the fifth solvent is toluene; b9) in step S1-2, the palladium catalyst is PdCl2(dppf); b10) in step S1-2, the molar ratio of the 5-bromoacenaphthene, the alkylboric acid and the second inorganic base is 1:1.5:1.5 to 1:2:3; b11) In step S1-2, the purification process is as follows: separating the reaction solution, concentrating the organic phase to dryness, dissolving it in petroleum ether, filtering it with silica gel, concentrating the filtrate, adding methanol to pulp, filtering, and drying it.

7. A photoresist, characterized in that: The method comprises the photoacid generator as claimed in claim 1 or 2.

8. The photoresist according to claim 7, characterized in that Also included are polymer resins, crosslinking agents, acid diffusion inhibitors, additives and solvents.

9. The photoresist according to claim 8, characterized in that The photoresist comprises the following components in percentage by mass:

10. The photoresist according to claim 9, characterized in that It also includes at least one of the following technical features: c1) The molecular structural formula of the polymer resin is: Wherein x=60~95, y=5~40; c2) The molecular structural formula of the cross-linking agent is: c3) the acid diffusion inhibitor is triethanolamine; c4) the additive is a fluorocarbon surfactant; c5) The solvent is propylene glycol methyl ether acetate.

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