Sulfonimide salt photo-acid generator and application thereof in photoresist

Abstract

The invention discloses a sulfonyl imide salt photo-acid generator and an application of the sulfonyl imide salt photo-acid generator in a deep ultraviolet chemical amplification type photoresist. The structure of the photoacid generator is shown as a formula I, wherein R is an aromatic group. The sulfonimide salt is used as a photoacid generator and is mixed with polymer resin and a solvent to prepare the photoresist, and the photoetching effect is excellent. The excellent photoetching effect is based on that the sulfonyl imide salt anions contain aromatic groups, so that the intensity, boiling point and volume of the photogenerated acid can be further increased, and the volatilization and migration of the photogenerated acid are reduced, thereby reducing the line edge roughness; by introducing aromatic groups, the conjugation degree of the PAG can be improved, and the stability of the PAG is enhanced; the aromatic group can also change the polarity of the PAG and improve the solubility of the PAG in the photoresist, so that the PAG is more uniformly distributed in a photoresist system; the aromatic groups can also increase the C / H ratio of PAG, and improve the etching resistance of the photoresist. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of photolithography in micro-fabrication, and in particular relates to a photoacid generator and application thereof in deep ultraviolet chemical amplification type photoresist. Background Art

[0002] Photolithography is a process that uses the photochemical reaction principle of photoresist and chemical and physical etching methods to transfer the pattern on the mask to the wafer. Photoresist, also known as photoresist, refers to an etching-resistant photosensitive material whose solubility changes significantly when exposed to ultraviolet light, electron beam, etc.

[0003] According to the chemical reaction mechanism, photoresists can be divided into positive photoresists and negative photoresists. Positive photoresists refer to photoresists in which, after exposure and development in the photolithography process, the exposed part of the coating is dissolved in the developer while the unexposed part is retained to form an image; negative photoresists are the opposite of positive photoresists, in which the unexposed part is dissolved while the exposed part forms an image.

[0004] The traditional photolithography resolution follows the Rayleigh formula: d = kλ / NA, where d is the minimum line width of the photolithography, k is the process coefficient, λ is the exposure wavelength in the photolithography process, and NA is the aperture size. Improving the minimum line width in the traditional photolithography process can be achieved by increasing the aperture of the lens of the photolithography equipment or by reducing the exposure wavelength used in the photolithography process. According to the different wavelengths of the exposure light source, photoresists can be divided into ultraviolet, deep ultraviolet and extreme ultraviolet photoresists.

[0005] Compared with ultraviolet light, deep ultraviolet light has a lower intensity. In order to meet the photosensitivity requirements, deep ultraviolet photoresists are generally chemically amplified photoresists. The working mechanism of chemically amplified photoresists is that the photoacid generator decomposes to produce acid during the exposure process. During the post-baking process, the acid catalyzes the acid-labile groups in the polymer resin to undergo a chemical reaction. After the catalytic reaction is completed, the acid is released again to continue to catalyze the reaction of other acid-labile groups until all acid-labile groups in the polymer resin in the exposed area are completely removed. Therefore, a small amount of photoacid generator can remove all acid-labile groups in the polymer resin after exposure, thereby changing the solubility of the polymer resin in the developer and achieving the effect of chemical amplification. This reduces the requirements for the photoacid generator content and exposure energy in the photoresist.

[0006] Chemically amplified photoresists are mainly composed of polymer resins, photoacid generators and solvents. The polymer resin is the skeleton of the photoresist and determines the basic properties of the photoresist, such as hardness, flexibility, and adhesion. The photoacid generator (PAG) produces a trace amount of acid during the exposure process to react with the main resin for deprotection, increasing the solubility difference between the exposed area and the non-exposed area in the developer. The solvent is the largest component in the photoresist, which keeps the photoresist in a liquid state and has almost no effect on the chemical properties of the photoresist.

[0007] Photoacid generator is the core component of chemically amplified photoresist. Its structure and properties have a great influence on the photolithographic performance of photoresist. Photoacid generators are mainly divided into non-ionic and ionic types. Non-ionic PAG has high solubility in organic solvents, good compatibility with polymer resins, low acid toxicity, wide absorption spectrum, simple synthesis, and is mostly used in UV photoresists; ionic PAG has higher thermal stability and photosensitivity, stronger acid production ability, and is mostly used in deep ultraviolet photoresists. Although the anion of ionic PAG is usually not optically active, it is crucial to the performance of PAG. The structure of the anion determines the various properties of the photogenerated acid generated after the PAG is irradiated, such as acidity, volume, volatility, diffusivity, solubility and stability, etc. These properties have a direct impact on the morphology of the photolithographic pattern.

[0008] The traditional anion of ionic photoacid generator is SbF 6 - , AsF 6 - PF 6 - However, they have poor solubility in organic media and are incompatible with semiconductor processing because the presence of group V doping atoms can change the electronic properties of silicon, and antimony, arsenic, etc. are toxic heavy metals. Commonly used ionic photoacid generator anions also include perfluoroalkyl sulfonic acid anions, which have good compatibility with semiconductors, but there are problems such as the photoacid generator is easy to segregate above the photoresist film, the generated photoacid is easy to volatilize, and the acid migration during the post-baking process, which leads to uneven acid-catalyzed photochemical reactions in the exposure area, large roughness of the edges of the photolithography pattern lines, and low resolution.

[0009] Patent CN114702458A discloses a benzopentacyclic-phenylalkynylsulfonium salt derivative and a preparation method thereof. The prepared sulfonium salt has good light absorption and photoacid generation efficiency in the near ultraviolet-visible light region.

[0010] Patent CN111077731A discloses a sulfonate compound containing a phytol structure and a preparation method thereof, which has a good hydrophilic-lipophilic balance and low diffusivity.

[0011] Patent CN111116546A discloses a sulfonium sulfonate photoacid generator synthesized from beta-eucalyptol and a synthesis method thereof. The synthetic raw material beta-eucalyptol contains aliphatic rings and has excellent etching resistance.

[0012] Patent CN111138408A discloses a sulfonium sulfonate photoacid generator synthesized from cedar alcohol and a synthesis method thereof. The structure of the sulfonium sulfonate photoacid generator contains an ester group, which can increase the fat solubility of the photoacid generator and is conducive to forming a more uniform photoresist.

[0013] However, the above patents all have problems such as poor compatibility between the photoacid generator and the polymer resin, low sensitivity, and diffusion of the photogenerated acid during the post-exposure baking process, which leads to greater line edge roughness and lower photoresist resolution. Summary of the invention

[0014] In view of the problems and shortcomings in the prior art, the present invention provides a sulfonyl imide salt photoacid generator and its application in deep ultraviolet chemical amplified photoresist. The photoacid generator of the present invention achieves excellent effects in improving photochemical reaction efficiency, reducing acid volatilization and migration, stability, etc.; and the photoresist prepared by using the sulfonyl imide salt as the photoacid generator has excellent photolithography effect.

[0015] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0016] First, the present invention provides a photoacid generator, wherein the photoacid generator is a sulfonimide salt, and the sulfonimide salt is a compound as shown in Formula I:

[0017]

[0018] In formula I, R is an aromatic group.

[0019] Further, the R is selected from any one of the following groups:

[0020]

[0021] That is, the sulfonimide salt is any one of the following compounds of structures A1, A2, A3 and A4:

[0022]

[0023] In addition, the present invention also provides a deep ultraviolet chemical amplification type photoresist, which comprises the following components: the above-mentioned sulfonyl imide salt photoacid generator, a polymer resin and a solvent.

[0024] Wherein, the polymer resin can be a polymer that can be used for deep ultraviolet (DUV) light to undergo photochemical reaction. For example, the polymer resin can be a polymer mixed with a photoacid generator, which generates an acid when exposed to light such as deep ultraviolet light and reacts chemically with it, and the acid generated in this way causes the polymer to undergo a chemical reaction so that the polymer increases its hydrophilicity or hydrophobicity. It should be understood that the polymer resin does not have to be directly sensitive to light; for example, exposure of the polymer resin to light does not necessarily change the chemical composition of the polymer resin, although the chemical composition of the polymer resin can be changed due to the acid generated by the exposed photoacid generator mixed with the polymer resin. In some embodiments, the solubility of the polymer resin in alkali can be increased due to a photochemical reaction. In some embodiments, the polymer resin can have a structure in which a protecting group is bonded to a repeating unit, and the protecting group can be deprotected during the exposure process, so that the polymer resin is well soluble in alkali; the deprotected protecting group can generate a new acid for chemical amplification.

[0025] More specifically, the polymer resin may be a polystyrene resin, a polyacrylic resin or a combination thereof. The polystyrene resin may be a resin having a repeating unit as shown in formula (II). 3a is a hydrogen atom or C 1-6 Alkyl, and R 3b It is an acid-dissociated protecting group.

[0026]

[0027] More specifically, the polystyrene resin may include any of the following polymerizable compounds as a repeating unit, examples of which may include but are not limited to: monocarboxylic acids, such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids, such as maleic acid, fumaric acid, and itaconic acid; methacrylic acid derivatives having a carboxyl group and an ester bond, such as 2-methacryloyloxyethylsuccinic acid, 2-methacryloyloxyethylmaleic acid, 2-methacryloyloxyethylphthalic acid, and 2-methacryloyloxyethylhexahydrophthalic acid; (meth) alkyl acrylates, such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate; hydroxyalkyl (meth) acrylates, such as 2-hydroxyethyl (meth) acrylate and (meth) acrylate. The present invention also includes 2-hydroxypropyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate; dicarboxylic acid diesters such as diethyl maleate and dibutyl fumarate; vinyl-containing aromatic compounds such as styrene, α-methylstyrene, chlorostyrene, chloromethylstyrene, vinyltoluene, hydroxystyrene, tert-butoxycarbonyloxystyrene, α-methylhydroxystyrene and α-ethylhydroxystyrene; vinyl-containing aliphatic compounds such as vinyl acetate; conjugated dienes such as butadiene and isoprene; nitrile-containing polymerizable compounds such as acrylonitrile and methacrylonitrile; chlorine-containing polymerizable compounds such as vinyl chloride and vinylidene chloride; and amide bond-containing polymerizable compounds such as acrylamide and methacrylamide.

[0028] The polyacrylic acid resin may be a resin having a repeating unit represented by formula (III).

[0029]

[0030] In formula (III), R 4a is a hydrogen atom, C 1 -C 6 Straight or branched alkyl, fluorine atom or C 1 -C 6 A linear or branched fluorinated alkyl group, and R 4b It is an acid-dissociated protecting group.

[0031] In the embodiment of the photoresist, the polymer resin may also include a (meth)acrylate-based polymer. The (meth)acrylate-based polymer may be an aliphatic (meth)acrylate-based polymer, and may include, for example, polymethyl methacrylate (PMMA), poly(tert-butyl methacrylate), poly(methacrylic acid), poly(norbornyl methacrylate), a binary or ternary copolymer polymer resin of repeating units of the above-mentioned (meth)acrylate-based polymers, or a combination thereof.

[0032] More specifically, the polyacrylic resin may include any of the following polymerizable compounds as repeating units. Examples of polymerizable compounds may include, but are not limited to: acrylates having ether bonds, such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate; monocarboxylic acids, such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids, such as maleic acid, fumaric acid, and itaconic acid; methacrylic acid derivatives having carboxyl groups and ester bonds, such as 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid, 2-methacryloyloxyethyl phthalic acid, and 2-methacryloyloxyethyl hexahydrophthalic acid; alkyl (meth)acrylates, such as (meth)acrylic acid; The present invention also includes methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate and cyclohexyl (meth)acrylate; hydroxyalkyl (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; aryl (meth)acrylates, such as phenyl (meth)acrylate and benzyl (meth)acrylate; dicarboxylic acid diesters, such as diethyl maleate and dibutyl fumarate; aromatic compounds containing vinyl groups, such as styrene, α-methylstyrene, chlorostyrene, chloromethylstyrene, vinyltoluene, hydroxystyrene, α-methylhydroxystyrene and α-ethylhydroxystyrene; aliphatic compounds containing vinyl groups, such as vinyl acetate; conjugated dienes, such as butadiene and isoprene; polymerizable compounds containing nitrile groups, such as acrylonitrile and methacrylonitrile; polymerizable compounds containing chlorine, such as vinyl chloride and vinylidene chloride; and polymerizable compounds containing amide bonds, such as acrylamide and methacrylamide.

[0033] In the embodiment of the photoresist, the weight average molecular weight (Mw) of the polymer resin may be 5000 to 100,000, for example 7000 to 10,000, for example 8000. The Mw value may be a value measured by gel permeation chromatography (GPC) by setting polystyrene as a standard.

[0034] Furthermore, in the deep ultraviolet chemically amplified photoresist, the solvent may be one or more of propylene glycol methyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, ethyl acetate, ethylene glycol monomethyl ether acetate, tetrahydrofuran, acetone, cyclohexanone or methanol, preferably propylene glycol monomethyl ether acetate.

[0035] In the deep ultraviolet chemical amplified photoresist, the weight ratio of the sulfonimide salt photoacid generator, the polymer resin and the solvent is 5-100:100:500-1500, and a photoresist with good photolithography effect can be obtained. Furthermore, the weight of the polymer resin can be 60 parts; in the deep ultraviolet chemical amplified photoresist, the weight of the sulfonimide salt can be 40 parts, based on 60 parts by weight of the polymer resin; in the deep ultraviolet chemical amplified photoresist, the weight of the solvent can be 900 parts, based on 60 parts by weight of the polymer resin. For example, in a preferred embodiment of the present invention, the deep ultraviolet chemical amplified photoresist is prepared by dissolving 40 parts by weight of the sulfonimide salt and 60 parts by weight of the polymer resin into 600 parts by weight of propylene glycol monomethyl ether acetate and 300 parts by weight of ethyl lactate.

[0036] The preparation method of the deep ultraviolet chemically amplified photoresist may include the following steps: uniformly mixing the sulfonimide salt, the polymer resin and the solvent. The mixing is a conventional operation in the art. The mixing temperature is room temperature. After the mixing is completed, filtering may also be included. The filtering method is a conventional filtering method in the art, preferably using a filter, and the filter membrane pore size of the filter is 150 to 250 nm, preferably 220 nm.

[0037] The present invention also provides a method for using the above-mentioned photoresist, wherein the method comprises the following steps:

[0038] Step 1: coating the above-mentioned deep ultraviolet chemically amplified photoresist on the surface of the substrate to form a photoresist layer;

[0039] Step 2: pre-baking the photoresist layer;

[0040] Step 3: Copy the pattern on the mask to the pre-baked photoresist layer by exposure;

[0041] Step 4: baking the exposed photoresist layer;

[0042] Step 5: Apply a developer to the baked photoresist layer for development to obtain a photolithography pattern.

[0043] In step 1, the substrate is a silicon wafer;

[0044] In step 1, the coating method is spin coating;

[0045] In step 1, the thickness of the photoresist layer is 100 to 500 nm, preferably 200 nm;

[0046] In step 2, the pre-baking temperature is 80-130° C., preferably 100° C.;

[0047] In step 3, the exposure wavelength is 190 to 260 nm, preferably 254 nm;

[0048] In step 4, the baking temperature is 80-130° C., preferably 100° C.;

[0049] In step 5, the developer is a tetramethylammonium hydroxide aqueous solution, for example, a tetramethylammonium hydroxide aqueous solution with a mass percentage of 2.38%;

[0050] In step 5, the developing temperature is 20-25° C., preferably 23° C.;

[0051] In step 5, the development time is 5 to 60 seconds, preferably 10 seconds.

[0052] Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The sulfonimide salt of the present invention has high lipophilicity, high solubility in common photoresist solvents, and good compatibility with polymer resins.

[0055] (2) The sulfonimide salt anion of the present invention is highly delocalized and weakly coordinated with nitrogen as the center, and the corresponding photogenerated acid is a superacid, which can increase the efficiency of acid-catalyzed photochemical reactions.

[0056] (3) The photogenerated acid corresponding to the sulfonimide salt of the present invention is a high-boiling-point acid, which can reduce the volatilization of the photogenerated acid, thereby improving the trapezoidal morphology of the pattern and reducing the pollution to the photolithography equipment.

[0057] (4) The sulfonimide salt and conjugate acid of the present invention are highly stable and can remain stable under high temperature, high reduction or oxidation and extreme pH.

[0058] (5) The aromatic group contained in the sulfonimide salt anion of the present invention can further increase the intensity, boiling point and volume of the photogenerated acid, reduce the volatilization and migration of the photogenerated acid, and thus reduce the line edge roughness; the introduction of the aromatic group can increase the conjugation degree of PAG and enhance its stability; the aromatic group can also change the polarity of PAG, increase its solubility in the photoresist, and make PAG more evenly distributed in the photoresist system; the aromatic group can also increase the C / H ratio of PAG and increase the etching resistance of the photoresist. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 This is the H NMR spectrum of the photoacid generator in Example 1 of the present invention.

[0061] Figure 2 This is the H NMR spectrum of the photoacid generator in Example 2 of the present invention.

[0062] Figure 3 This is the H NMR spectrum of the photoacid generator in Example 3 of the present invention.

[0063] Figure 4 This is the H NMR spectrum of the photoacid generator in Example 4 of the present invention.

[0064] Figure 5 This is the H NMR spectrum of the photoacid generator in Comparative Example 1 of the present invention.

[0065] Figure 6 Thermogravimetric analysis curves of the photoacid generators in Examples 1 to 4 and Comparative Example 1 of the present invention.

[0066] Figure 7 The ultraviolet absorption curves of the photoacid generators in Examples 1 to 4 and Comparative Example 1 of the present invention are shown.

[0067] Figure 8 The deep ultraviolet photoresist acid diffusion length curves in Examples 1 to 4 of the present invention and Comparative Example 1 are shown.

[0068] Fig. 9 These are optical microscope patterns of the photolithography morphology obtained by the deep ultraviolet photoresists in Examples 1 to 4 of the present invention and Comparative Example 1.

[0069] Fig.10 The lithography atomic force microscope patterns obtained by the deep ultraviolet photoresists in Examples 1 to 4 of the present invention and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0070] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0071] In various embodiments of the present invention, a sulfonyl imide salt of any structure of A1, A2, A3 and A4 is prepared, and the sulfonyl imide salt is used as a photoacid generator in the preparation of a deep ultraviolet chemically amplified photoresist.

[0072]

[0073] Example 1

[0074] In this embodiment, the sulfonyl imide salt of the A1 structure is prepared, and the deep ultraviolet chemically amplified photoresist is prepared using the sulfonyl imide salt as a photoacid generator, as follows.

[0075] First, the sulfonimide salt of structure A1 is synthesized, and the synthesis route is as follows:

[0076]

[0077] According to the synthetic route, the specific synthetic steps include:

[0078] (1) 10.00 g of benzenesulfonyl chloride and 150.00 g of 25 wt% ammonia water were mixed and reacted at room temperature for 2 h, and the reaction solution was extracted with 150 ml of dichloromethane. After separation, the aqueous phase was extracted again with 50 ml of dichloromethane, and then the organic phases obtained from the two extractions were combined and washed with 50 ml of saturated NaCl solution, and then the organic phase was removed from the solvent by rotary evaporation at 30° C. to obtain a beige solid, which is the intermediate (a) in the above synthetic route.

[0079] (2) Add 7.80g of intermediate a and 80mL of dichloromethane to a flask, then add 10.00g of triethylamine, pass nitrogen gas for protection, use an ice-water bath to lower the internal temperature of the flask to 0°C, slowly inject 16.80g of trifluoromethanesulfonic anhydride, and keep the internal temperature of the flask at 0°C, then slowly heat the flask to room temperature for 2h. Extract the reaction solution with 80ml of deionized water. After separation, wash the organic phase with 80ml of saturated NaCl solution, and then remove the solvent from the organic phase by rotary evaporation at 30°C to obtain a brown-black solid, which is the intermediate (b) in the above-mentioned synthetic route;

[0080] (3) 11.00 g of intermediate b was dissolved in 30 ml of methanol, and then slowly added dropwise to an alkaline solution prepared by 16.00 g of potassium hydroxide and 100 ml of deionized water. After reacting for 0.5 h, the filter cake was filtered. The filter cake was washed with deionized water until neutral, then rinsed with ether, and then dried in a vacuum oven at 65°C for 24 h to obtain a brown solid, which is the intermediate (c) in the above synthetic route;

[0081] (4) 5.08 g of intermediate c and 7.99 g of triphenylsulfonium bromide were dispersed in a mixed solvent of 70 mL of dichloromethane and 70 mL of deionized water, and reacted at room temperature for 10 h. After the reaction, the liquids were separated, and the organic phase was washed three times with deionized water. The organic phase was subjected to rotary evaporation at 30° C. to remove the solvent, and then dried in a vacuum oven at 65° C. for 24 h to obtain a brownish yellow solid, namely, the sulfonimide salt of structure A1.

[0082] Next, the sulfonimide salt synthesized in this example was used as a photoacid generator to prepare a photoresist.

[0083] The details are as follows:

[0084] 40 parts by weight of the sulfonimide salt and 60 parts by weight of the polymer resin are dissolved in 600 parts by weight of propylene glycol monomethyl ether acetate and 300 parts by weight of ethyl lactate, mixed evenly, and filtered using a 0.22 μm filter to prepare a deep ultraviolet chemically amplified photoresist.

[0085] Among them, in the present invention, the inventors explored that when the sulfonyl imide salt photoacid generator of each embodiment of the present invention is used to prepare a photoresist, the weight ratio of the photoacid generator, the polymer resin and the solvent satisfies the mixing ratio of 5 to 100:100:500 to 1500, and a photoresist with a photolithography effect equivalent to that of the present embodiment can be obtained.

[0086] In this embodiment, the preparation method of the polymer resin used in preparing the photoresist is as follows:

[0087] (1) About 22.74 g of p-acetoxystyrene and about 1.02 g of 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid were added to a flask filled with nitrogen, and then 31 g of dioxane was added to the flask. After stirring evenly, the flask was heated to 70° C., and then a mixed solution of dioxane (5 g) and azobisisobutyronitrile (0.24 g) was slowly injected into the flask. The reaction was carried out at 70° C. for 8 hours, and the reaction was stopped;

[0088] (2) Then the reaction solution was added dropwise to a beaker containing n-hexane (500 ml) and stirred continuously to produce precipitation. The addition was completed in 30 minutes. After 1 hour, the stirring was stopped and the solid precipitate was obtained by filtration. The solid precipitate was placed in a vacuum drying oven at 100°C and dried for 24 hours to obtain polymerized para-acetoxystyrene;

[0089] (3) Add about 14.00 g of poly(p-acetoxystyrene) and about 7.26 g of sodium hydroxide into a flask, then add 60 ml of tetrahydrofuran and 45 ml of deionized water into the flask, stir evenly, and heat the flask to 40° C. React at 40° C. for 6 hours, stop the reaction, add hydrochloric acid dropwise to adjust the solution pH to 7, and let stand until the solution separates;

[0090] (4) The organic phase of the reaction solution was then added dropwise to a beaker containing deionized water (500 ml) and stirred continuously to produce a precipitate. The addition was completed in 30 minutes. After 1 hour, the stirring was stopped and the solid precipitate was obtained by filtration. The solid precipitate was placed in a vacuum drying oven at 65°C and dried for 24 hours to obtain poly(p-hydroxystyrene).

[0091] (5) Add about 9.00 g of poly(p-hydroxystyrene), about 0.92 g of 4-dimethylaminopyridine and about 10.63 g of di-tert-butyl dicarbonate into a flask, then add 120 ml of acetone into the flask, stir evenly and heat the flask to 25° C. React at 25° C. for 6 hours and then stop the reaction;

[0092] (6) The reaction solution was then added dropwise to a beaker containing n-hexane (500 ml) and stirred continuously to produce a precipitate. The addition was completed in 30 minutes. After 1 hour, stirring was stopped, and the solid precipitate was filtered and dissolved in 50 ml of acetone;

[0093] (7) Repeat step (6) twice, and then add the reaction solution dropwise into a beaker containing n-hexane (500 ml) for 30 minutes. After 1 hour, stop stirring, filter to obtain a solid precipitate, and dry the solid precipitate in a vacuum drying oven at 65°C for 24 hours to obtain a polymer resin. The structural formula of the polymer resin finally prepared is as follows:

[0094]

[0095] Wherein x:y=40.9:59.1; its weight average molecular weight (Mw) is 9760; and its polydispersity index (PDI) is 1.42.

[0096] Example 2

[0097] In this embodiment, the sulfonyl imide salt of the A2 structure is prepared, and the deep ultraviolet chemically amplified photoresist is prepared using the sulfonyl imide salt of the A2 structure as a photoacid generator.

[0098] The specific route for synthesizing the sulfonimide salt of structure A2 is as follows:

[0099]

[0100] The synthesis steps were the same as those in Example 1, except that benzenesulfonyl chloride in step (1) of synthesizing the sulfonyl imide salt was replaced with naphthalenesulfonyl chloride. The rest was the same as in Example 1.

[0101] Again, the sulfonimide salt of structure A2 synthesized in this example is used as a photoacid generator to prepare a photoresist, and the preparation process is the same as that in Example 1.

[0102] Example 3

[0103] In this embodiment, the sulfonyl imide salt of the A3 structure is prepared, and the deep ultraviolet chemically amplified photoresist is prepared using the sulfonyl imide salt of the A3 structure as a photoacid generator.

[0104] The specific route for synthesizing the sulfonimide salt of structure A3 is as follows:

[0105]

[0106] The synthesis steps were the same as those in Example 1, except that benzenesulfonyl chloride in step (1) of synthesizing the sulfonyl imide salt was replaced with o-fluorobenzenesulfonyl chloride. The rest was the same as in Example 1.

[0107] Again, the sulfonimide salt of the A3 structure synthesized in this example is used as a photoacid generator to prepare a photoresist, and the preparation process is the same as that in Example 1.

[0108] Example 4

[0109] In this embodiment, the sulfonyl imide salt of the A4 structure is prepared, and the deep ultraviolet chemically amplified photoresist is prepared using the sulfonyl imide salt of the A4 structure as a photoacid generator.

[0110] The specific route for synthesizing the sulfonimide salt of structure A4 is as follows:

[0111]

[0112] The synthesis steps were the same as those in Example 1, except that benzenesulfonyl chloride in step (1) of synthesizing the sulfonyl imide salt was replaced with o-toluenesulfonyl chloride. The rest was the same as in Example 1.

[0113] Again, the sulfonimide salt of the A4 structure synthesized in this example is used as a photoacid generator to prepare a photoresist, and the preparation process is the same as that in Example 1.

[0114] Comparative Example 1

[0115] In this comparative example, a sulfonyl imide salt having a C1 structure is prepared, and a deep ultraviolet chemically amplified photoresist is prepared using the sulfonyl imide salt having a C1 structure as a photoacid generator.

[0116] Among them, the structure of C1 is as follows:

[0117]

[0118] The specific synthesis route of the sulfonimide salt of the C1 structure is as follows:

[0119]

[0120] According to the above synthesis route, the specific steps for synthesizing the sulfonimide salt of the C1 structure are:

[0121] 5.15 g of triphenylsulfonium bromide and 3.19 g of potassium bis(trifluoromethanesulfonyl)imide were dispersed in a mixed solvent of 50 mL of dichloromethane and 50 mL of deionized water, and reacted at room temperature for 10 h. After the reaction, the liquid was separated, and the organic phase was washed three times with deionized water. The organic phase was removed from the solvent by rotary evaporation at 30 ° C, and then dried in a vacuum oven at 65 ° C for 24 h to obtain a white solid, i.e., a sulfonyl imide salt having a C1 structure.

[0122] Again, the sulfonimide salt of the C1 structure synthesized in this comparative example was used as a photoacid generator to prepare a photoresist, and the preparation process was the same as that of Example 1.

[0123] Structural characterization, performance testing and analysis of the photoacid generators of various embodiments and comparative examples:

[0124] The structures of the sulfonyl imide salt photoacid generators synthesized in the above embodiments and comparative examples were characterized by H-NMR spectroscopy. In addition, the performance of the sulfonyl imide salt photoacid generators synthesized in the above embodiments and comparative examples was tested, and the acid diffusion length and photolithography effect of the photoresists prepared in the embodiments and comparative examples were compared and analyzed. The details are as follows.

[0125] 1) Characterization of sulfonyl imide photoacid generator by H NMR spectrum

[0126] Test method: The sulfonyl imide photoacid generators synthesized in each example and comparative example were used as test objects. 0.005 g of the photoacid generator was weighed and dissolved in 0.6 ml of deuterated solvent. 1 The molecular structure of the photoacid generator was characterized by H NMR.

[0127] The test results of Examples 1 to 4 and Comparative Example 1 correspond to Figure 1-5 , the results are as follows:

[0128] Embodiment 1: 1 H-NMR (400MHz, CDCl3) δ (ppm): 7.99–7.87 (m, 2H), 7.77–7.62 (m, 15H), 7.42–7.30 (m, 3H);

[0129] Embodiment 2: 1 H-NMR (400MHz, CDCl 3 )δ(ppm):8.97–8.86(m,1H),8.23(d,J=7.3Hz,1H),7.85(d,J=8.2Hz,1H),7.81–7.74(m ,1H),7.72–7.61(m,3H),7.60–7.50(m,12H),7.48–7.38(m,2H),7.34(t,J=7.8Hz,1H);

[0130] Embodiment 3: 1 H-NMR (400MHz, CDCl 3 )δ(ppm):7.90–7.81(m,1H),7.70–7.55(m,15H),7.38–7.30(m,1H),7.06–6.99(m,1H),6.99–6.90(m,1H).;

[0131] Embodiment 4: 1 H-NMR (400MHz, CDCl 3 )δ(ppm):7.95(d,J=8.0Hz,1H),7.64(dt,J=14.8,7.6Hz,15H),7.23(t,J=7.4Hz,1H),7.12(d,J=7.4Hz,1H),7.06(t,J=8.3Hz,1H),2.63(s,3H);

[0132] Comparative Example 1: 1 H-NMR (500MHz, CDCl3) δ (ppm): 7.80 (t, J = 7.4Hz, 3H), 7.72 (t, J = 7.8Hz, 6H), 7.66 (d, J = 7.7Hz, 6H).

[0133] 2) Solubility test of sulfonimide photoacid generator

[0134] Test method: The sulfonimide photoacid generators synthesized in each embodiment and comparative example were used as test objects, 0.3 g of the photoacid generator was weighed, added to 10 g of propylene glycol monomethyl ether, and magnetically stirred for 20 minutes to observe the solubility. The test results are shown in Table 1 below. The sulfonimide photoacid generators in each embodiment and comparative example all have good solubility.

[0135] 3) Thermal stability test of sulfonimide photoacid generator

[0136] Test method: The sulfonyl imide salt photoacid generators synthesized in each example and comparative example were used as test objects, 0.005 g of the photoacid generator was weighed, and a thermogravimetric analyzer was used to analyze the N 2 The temperature was raised from 50°C to 600°C at a rate of 10°C / min to measure the thermal decomposition temperature of the photoacid generator. Figure 6 2 is the thermogravimetric analysis curve of the sulfonyl imide salt photoacid generator in Examples 1 to 4 and Comparative Example 1. It can be seen from the figure that the photoacid generators in each Example and Comparative Example have a relatively high thermal decomposition temperature. The specific thermal decomposition temperatures are shown in Table 1.

[0137] 4) Sulfonyl imide photoacid generator UV absorption test

[0138] Test method: The sulfonyl imide salt photoacid generators synthesized in each embodiment and comparative example were used as test objects, and ethanol was used as a solution to prepare a solution with a concentration of 5x10 -5 mol / L solution, and use a UV-visible spectrophotometer to measure the ultraviolet absorption of the photoacid generator, with the scanning range set to 190-400nm. The test results are as follows Figure 7 , the figure shows the ultraviolet absorption curves of the photoacid generator in Examples 1 to 4 and Comparative Example 1, and the ultraviolet absorption is stronger at 190 to 260 nm.

[0139] 5) Test of quantum yield of acid generated by sulfonimide photoacid generator

[0140] The quantum yield of acid generation by a photoacid generator is the ratio of the number of photoacid molecules generated to the number of absorbed photons. The testing method is as follows: the sulfonyl imide photoacid generators synthesized in each embodiment and comparative example are respectively used as test objects, and the sodium salt of tetrabromophenol blue (TBPB) is used as an acid indicator. In the UV-visible spectrum, TBPB will have a strong absorption at 619nm, and in the presence of acid, the absorbance at this point will decrease quantitatively. With the concentration of perfluorobutanesulfonic acid as the horizontal coordinate and the absorbance of a mixed solution of perfluorobutanesulfonic acid, TBPB and sodium hydroxide at 619nm as the vertical coordinate, a standard working curve is obtained, and the slope (K) of the curve is calculated. With the exposure dose as the horizontal coordinate and the absorbance of a mixed solution of the photoacid generator PAG, TBPB and sodium hydroxide at 619nm as the vertical coordinate, a PAG acid generation kinetic curve is obtained, and the slope (K) of the curve is calculated. a ). The quantum yield of acid generation of the photoacid generator PAG is calculated according to the following equation:

[0141] Φ f =(1495.82 / λ)K a / K

[0142] Where K a is the slope of the acid production kinetic curve, in cm 2 / mJ; λ is the exposure wavelength, in nm; K is the slope of the standard working curve, in L / mol.

[0143] The test results are shown in Table 1. The acid generation quantum yields of Examples 1 to 4 and Comparative Example 1 are substantially the same because the photosensitive acid generation group of the ionic PAG is a cation, and the cations of Examples 1 to 4 and Comparative Example 1 are the same.

[0144] 6) Photoresist acid diffusion length test

[0145] The photoresists prepared in the embodiments and comparative examples were used as test objects to measure their diffusion lengths. The test method is as follows:

[0146] 100 parts by weight of the polymer resin is dissolved in 600 parts by weight of propylene glycol monomethyl ether acetate and 300 parts by weight of ethyl lactate, mixed evenly, and filtered using a 0.22 μm filter to obtain a polymer resin solution. The polymer resin used in Example 1 to prepare the photoresist is used.

[0147] First, a polymer resin solution is spin-coated on a silicon wafer as a first film, and its thickness is measured. After pre-baking at 100°C for 60 seconds, the photoresist prepared in each embodiment and comparative example is spin-coated on the first film. After pre-baking at 100°C for 60 seconds, it is exposed to 254nm ultraviolet light, and then baked at 100°C for 60 seconds after exposure. Then, it is developed at 23°C for 10 seconds using a 2.38wt% tetramethylammonium hydroxide aqueous solution. The thickness of the film on the silicon wafer after development is measured, and the acid diffusion length is the difference in thickness between the first film and the film after development.

[0148] The test results are as follows Figure 8 The photoresist acid diffusion length curves of Examples 1 to 4 and Comparative Example 1 show that the photoresists prepared using the sulfonyl imide salts synthesized in each example as the photoacid generator have a shorter acid diffusion length after photolithography, while the photoresist prepared using the photoacid generator shown in Comparative Example 1 as the photoacid generator has a longer acid diffusion length after photolithography.

[0149] 7) Photoresist lithography test

[0150] The photoresists prepared in the embodiments and comparative examples were used as test objects to measure their photolithography effects. Figure 9-10 The test results recorded are those of the following conditions:

[0151] The photoresists prepared in each embodiment and comparative example were spin-coated on a silicon wafer to obtain a photoresist film with a thickness of about 200 nanometers. After pre-baking at 100°C for 60 seconds, the film was exposed through a mask using 254nm ultraviolet rays, and then baked at 100°C for 60 seconds after exposure. Then, a 2.38wt% tetramethylammonium hydroxide aqueous solution was used for development at 23°C for 10 seconds. The shape of the pattern formed after photolithography was observed, and the line edge roughness (LER) was measured. The line edge roughness is defined as the distance difference between the farthest point and the nearest point on the line edge in the direction perpendicular to the line. The test results are shown in FIG. Figure 9-10 As shown, Fig. 9 Optical microscope patterns of the photolithographic morphologies obtained from the deep ultraviolet photoresists of Examples 1 to 4 and Comparative Example 1, wherein (a), (b), (c), (d), and (e) correspond to the photolithographic morphologies of the photoresists of Comparative Example 1, Example 1, Example 2, Example 3, and Example 4, respectively. Fig.10The atomic force microscope patterns of the photolithographic morphologies obtained by the deep ultraviolet photoresists in Examples 1 to 4 and Comparative Example 1, and Figures (a), (b), (c), (d), and (e) in the figure correspond to the photolithographic morphologies of the photoresists in Comparative Example 1, Example 1, Example 2, Example 3, and Example 4, respectively. It can be seen from the figures that the line patterns formed in each embodiment have clear line morphologies, fewer defects, and smaller LER; the line pattern formed in the comparative example has a poor morphology, rough edges, more defects, and a larger LER.

[0152] When the photoresists of the above embodiments are subjected to photolithography, any combination of the photolithography parameters satisfying the following preferred conditions will produce the same photolithography effect as the above embodiments. Figure 9-10 The results shown in are equivalent: the thickness of the coated photoresist layer is 100-500nm, the pre-baking temperature is 80-130℃, the exposure wavelength is 190-260nm, the post-development baking temperature is 80-130℃, the developing temperature is 20-25℃, and the developing time is 5-60s.

[0153] The test results of the above items are listed and compared in Table 1.

[0154] Table 1 Test results of the embodiments of the present invention and comparative examples

[0155]

[0156] As shown in Table 1, from the comprehensive comparison of the various properties of Comparative Examples 1 to 4 and Comparative Example 1, the sulfonyl imide salt photoacid generators of each embodiment have better solubility, higher thermal decomposition temperature, stronger ultraviolet absorption at 190 to 260 nm, and the prepared photoresist has a shorter acid diffusion length after photolithography, and the formed line pattern has a clear line morphology, fewer defects, and a smaller LER. In comparison, the photoresist prepared by the photoacid generator of Comparative Example 1 has a longer acid diffusion length after photolithography, and the formed line pattern has a poor morphology, a rougher edge, more defects, and a larger LER.

[0157] In summary, the present invention effectively overcomes the deficiencies in the prior art and has a high industrial utilization value. The above embodiments serve to illustrate the substantive content of the present invention, but do not limit the protection scope of the present invention. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and protection scope of the technical solution of the present invention.

Claims

1. A sulfonimide photoacid generator, characterized in that: The sulfonimide photoacid generator is a compound shown in formula I; In Formula I, R is any one of the following groups:

2. The sulfonimide photoacid generator according to claim 1, characterized in that: The sulfonimide photoacid generator is any one of the following compounds of structural formula A1, A2, A3 or A4:

3. The method for synthesizing a sulfonimide photoacid generator according to any one of claim 2, characterized in that: The synthetic routes of the sulfonimide photoacid generators of the structural formula A1, A2, A3 or A4 are respectively:

4. A deep ultraviolet chemically amplified photoresist, characterized in that: The deep ultraviolet chemically amplified photoresist is composed of the sulfonimide salt photoacid generator as described in any one of claims 1 to 2, a polymer resin and a solvent.

5. A deep ultraviolet chemically amplified photoresist according to claim 4, characterized in that: The polymer resin is any one of polystyrene resin, polyacrylic resin or a combination thereof.

6. A deep ultraviolet chemically amplified photoresist according to claim 4, characterized in that: The solvent is one or more of propylene glycol methyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, ethyl acetate, ethylene glycol monomethyl ether acetate, tetrahydrofuran, acetone, cyclohexanone or methanol.

7. A deep ultraviolet chemically amplified photoresist according to claim 4, characterized in that: In the deep ultraviolet chemically amplified photoresist, the weight ratio of the sulfonimide salt photoacid generator, the polymer resin and the solvent is 5-100:100:500-1500.

8. A deep ultraviolet chemically amplified photoresist according to claim 7, characterized in that: In the deep ultraviolet chemically amplified photoresist, the weight ratio of the sulfonimide salt photoacid generator, the polymer resin and the solvent is 40:60:

900.

9. The use of the deep ultraviolet chemically amplified photoresist according to any one of claims 4 to 8, characterized in that: The photoresist is used for photolithography, comprising the following steps: Step 1, coating the deep ultraviolet chemically amplified photoresist on the surface of a substrate to form a photoresist layer; Step 2, pre-baking the photoresist layer; Step 3, copying the pattern on the mask onto the pre-baked photoresist layer by exposure; Step 4, baking the exposed photoresist layer; Step 5, applying a developer to the baked photoresist layer for development to obtain a photolithography pattern.

10. The use of the photoresist according to claim 9, characterized in that: In step 1, the thickness of the photoresist layer is 100-500 nm; in step 2, the pre-baking temperature is 80-130° C.; in step 3, the exposure wavelength is 190-260 nm; in step 4, the baking temperature is 80-130° C.; in step 5, the developer is a tetramethylammonium hydroxide aqueous solution; the development temperature is 20-25° C.; and the development time is 5-60 s.

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