JP7117900B2 - Photo-Lewis acid generator for chemically amplified resist, and chemically amplified resist composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photo-Lewis acid generator for chemically amplified resists and a chemically amplified resist composition. More specifically, the present invention relates to a chemically amplified resist photo-Lewis acid generator and a chemically amplified resist composition capable of suppressing acid diffusion and forming a finer resist.

A chemically amplified resist composition (hereinafter referred to as a resist composition) is a composition that forms a resist pattern on a substrate by causing a difference in the dissolution rate of the exposed area and the unexposed area in a developer when irradiated with an energy beam. However, in recent years, as large-scale highly integrated circuits (LSI) have become more highly integrated and faster, there has been a demand for finer pattern formation. Ultraviolet rays are used, and lithography using high-energy rays such as electron beams (EB) and extreme ultraviolet rays (EUV) is expected in the future.

On the other hand, line width roughness (hereafter referred to as roughness), which is variation in line width, is one of the indices representing the resist resolution. . As one method for improving roughness, studies have been made to suppress acid diffusion in a resist composition. For example, Patent Document 1 discloses a resist composition that suppresses acid diffusion by using a sulfonium salt having a specific structure as a photoacid generator, and Patent Document 2 discloses a specific resist composition that functions as a photoacid generator. Patent Document 3 describes a resist composition using a polymer compound having a structure of as a base resin. A radiation-sensitive resin composition is disclosed comprising an inhibitor.

JP 2018-52832 A JP 2017-190402 A International Publication No. 2010/029965

As described above, resist compositions using various photoacid generators for suppressing acid diffusion in resist compositions have been proposed. Although this product is intended to suppress acid diffusion compared to conventional products, the suppression power is still insufficient, and there is a problem that the improvement of roughness is insufficient.
The present invention has been made in view of the above circumstances, and provides a photoacid generator capable of suppressing acid diffusion when used in a resist composition and providing a resist pattern with improved roughness, and the photoacid generator. An object of the present invention is to provide a resist composition containing the agent.

In order to achieve the above object, the present inventors conducted various studies, and found that in a resist composition using a Lewis acid as a photoacid generator, acid diffusion is suppressed and roughness is improved in order to obtain a resist pattern. The inventors have found that this is extremely effective, and arrived at the present invention.
That is, the present invention is a photo Lewis acid generator for chemically amplified resists. The present invention is also a composition for chemically amplified resists containing the photo Lewis acid generator for chemically amplified resists.

According to the present invention, the resist composition using the photo-Lewis acid generator can form a resist pattern in which acid diffusion is sufficiently suppressed and roughness is improved when a pattern is formed.

The present invention will be described in detail below.
A combination of two or more of the individual preferred embodiments of the invention described below is also a preferred embodiment of the invention.

<Photo Lewis Acid Generator for Chemically Amplified Resist>
The optical Lewis acid generator for chemically amplified resists of the present invention contains a compound having an anion moiety and a cation moiety. The compound having an anion moiety and a cation moiety may be a compound in which an anion moiety and a cation moiety form a salt. The anion portion can generate a Lewis acid by light irradiation.

[Anion part]
The anion moiety is not particularly limited as long as it can generate a Lewis acid by light, but examples thereof include boron and aluminum. Among them, it is preferable to use boron as the central atom. The group (or atom) substituting (or bonding) to the central atom of the anion moiety is not particularly limited, but examples thereof include a hydrocarbon group, a heterocyclic group such as a heteroaryl group, a hydroxyl group, a halogen atom, a hydrogen atom, and the like. .

The hydrocarbon group is not particularly limited, and examples thereof include an aliphatic hydrocarbon group and an aromatic hydrocarbon group. Examples of aliphatic hydrocarbon groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, n-pentyl, n-hexyl, n Alkyl groups such as -heptyl group, n-octyl group and 2-ethylhexyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; and aralkyl groups such as benzyl group and phenethyl group. Examples of the aromatic hydrocarbon group include aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group.
The aliphatic hydrocarbon group and the aromatic hydrocarbon group preferably have 30 or less carbon atoms, more preferably 20 or less carbon atoms. When the above group has a substituent, the number of carbon atoms in the entire group including the substituent is preferably within the above range.

A hydrocarbon group and a heterocyclic group may have a substituent. In addition, the hydrocarbon group having a substituent refers to a group in which one or more of the hydrogen atoms constituting the hydrocarbon group having no substituent is substituted with a substituent, and a heterocyclic group having a substituent refers to a group in which one or more of the hydrogen atoms constituting the heterocyclic ring having no substituent have been substituted with a substituent. Also, the substituent may be further substituted with another substituent.

The substituents are not particularly limited, for example, halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; hydroxyl group; alkoxy group such as methoxy group and ethoxy group; aryloxy group such as phenoxy group; Acyl groups such as alkylcarbonyl groups typified by groups and arylcarbonyl groups typified by benzoyl groups; Alkoxycarbonyl groups such as methoxycarbonyl groups, aryloxycarbonyl groups such as phenoxycarbonyl groups; Mercapto groups; Alkylthio groups such as methylthio groups; Arylthio groups such as phenylthio groups; Amino groups; substituted amino groups such as; amide groups such as alkylaminocarbonyl groups typified by N,N'-dimethylaminocarbonyl groups; cyano groups; nitro groups; alkylsulfonyl groups typified by mesyl groups; Substituted sulfonyl groups such as arylsulfonyl groups; and hydrocarbon groups as described above.

These substituents may be used alone or in combination of two or more, and the hydrocarbon group or heterocyclic group may contain one or more substituents. These substituents may also be directly bonded to the boron atom either singly or in combination of two or more.

The anion moiety may have at least one aryl group or an aryl group having at least one halogen atom, in particular an aryl group having at least one halogen atom. As the halogen atom, chlorine and fluorine are preferred, and fluorine is more preferred. Among them, it is preferable to have at least one aryl group having at least 3 halogen atoms, since the Lewis acid strength tends to increase and the properties as an acid generator tend to improve, and aryl having at least 5 halogen atoms It is further preferred to have at least one group.

In the aryl group having a halogen atom, the halogen atom may be directly bonded to the aryl group, or may be in a manner in which the halogen atom-containing group is bonded to the aryl group, or in a combination of these may have.
Examples of halogen atom-containing groups include haloalkyl groups such as trifluoromethyl, pentafluoroethyl, heptafluoropropyl, and perfluorooctyl groups; perfluorocyclopropyl, perfluorocyclobutyl, perfluorocyclopentyl, perfluorocyclopentyl, halocycloalkyl groups such as a fluorocyclohexyl group; haloalkoxy groups such as a trifluoromethoxy group, pentafluoroethoxy group, heptafluoropropoxy group and perfluorooctoxy group; halogenated sulfanyl groups such as a pentafluorosulfanyl group; .

Among the aryl groups having a halogen atom, aryl groups having at least one fluorine atom include, for example, a pentafluorophenyl group, a 2-fluorophenyl group, a 2,6-difluorophenyl group, a 2,4,6- fluoroaryl groups such as a trifluorophenyl group and a 2,3,5,6-tetrafluorophenyl group; (fluoroalkyl)aryl groups such as a trifluoromethylphenyl group and a pentafluoroethylphenyl group; fluoro-trifluoromethylphenyl fluoro-(fluoroalkyl)aryl groups such as groups; (fluorosulfanyl)aryl groups such as pentafluorosulfanylphenyl groups;
Among the aryl groups having a halogen atom, examples of aryl groups having at least one chlorine atom include chloroaryl groups such as pentachlorophenyl and 2-chlorophenyl.

When the anion moiety has an aryl group or an aryl group having at least one halogen atom, the number of aryl groups may be less than or equal to the valence (n) of the central atom, preferably 1 to n−1, more preferably 2 to n-1, particularly preferably n-1. When the central atom is boron, the valence (n) is 4.

The anion moiety is preferably represented by the following general formula (1).

(wherein Ar ¹ to Ar ³ are an aryl group or an optionally substituted aryl group, Y represents a substituent. Ar ¹ to Ar ³ may be the same or different. good.)
In the above formula (1), Ar ¹ to Ar ³ are aryl having at least one halogen atom, in that at least two of Ar ¹ to Ar ³ have improved Lewis acid strength and improved Lewis acid generating ability. is preferably a group, and more preferably all of Ar ¹ to Ar ³ are aryl groups having at least one halogen atom. Further, since Ar ¹ to Ar ³ may be the same or different, all of Ar ¹ to Ar ³ may be aryl groups having the same number of halogen atoms, or different numbers of A combination of aryl groups having halogen atoms may also be used.
Examples of the aryl group having at least one halogen atom include the groups exemplified above. Since the halogen atom is preferably fluorine, a fluorophenyl group is preferred, and a pentafluorophenyl group is particularly preferred. preferable.

In the above formula (1), Y includes, among the substituents exemplified above, a hydrocarbon group, a heterocyclic group, a hydroxyl group, and the like. or a hydroxyl group, more preferably an alkyl group or a hydroxyl group, and particularly preferably a hydroxyl group.

The compound of the present invention can generate a Lewis acid from the anion moiety upon irradiation with light, and such a Lewis acid preferably has n substituents bonded to the central atom, one of which is It is detached. Therefore, for example, when the anion moiety is represented by the above formula (1), a compound in which any one substituent among Ar ¹ to Ar ³ and Y is eliminated is generated as a Lewis acid. In particular, when Y is eliminated, a compound represented by the following general formula (2) is generated as a Lewis acid.

(In the formula, Ar ¹ to Ar ³ are the same as above.)
[Cation part]
The cation moiety is a counter cation of the anion moiety, and is not particularly limited as long as it can generate a Lewis acid from the anion moiety in combination with the anion moiety. HOMO-LUMO transition, or decomposition of cationic species by external electron donation, and charge transfer from anion to cation due to light irradiation, which accompanies elimination of substituents. It is preferable that the cationic moiety decomposes quickly or allows easy charge transfer from the anionic moiety. Thereby, the substituent can be rapidly eliminated from the anion moiety.

The cation moiety is preferably non-reactive with respect to the Lewis acid generated from the anion moiety. By combining a non-reactive cation with the anion moiety, the Lewis acid generated from the anion moiety can be efficiently utilized.

As the cation moiety or the cation moiety that is non-reactive with respect to the Lewis acid generated from the anion moiety, a cation moiety that does not have a group capable of forming a salt with a Lewis acid is preferable. Here, the group capable of forming a salt with a Lewis acid is, for example, a substituent that exhibits basicity and forms a salt with a Lewis acid to deactivate the ability to generate a Lewis acid from the anion moiety. , an amino group, an N-monosubstituted amino group, an imino group, and the like.

The central atom of the cation moiety is not particularly limited, but for example, it is preferably a heteroatom selected from sulfur, iodine, nitrogen, oxygen, and phosphorus. A sulfur atom is preferred, and an iodine atom is particularly preferred. Such a cation moiety having a heteroatom as a central atom is highly reactive with light, and thus easily generates a Lewis acid efficiently.

Among the central atoms of the cation moiety, the mode of existence of the heteroatom in the cation moiety having a heteroatom as the central atom is not particularly limited, and may be an atom constituting a chain structure, or a cyclic structure such as a heterocyclic ring. may be atoms constituting The heterocyclic ring may be either an aliphatic heterocyclic ring or an aromatic heterocyclic ring, but is particularly preferably an aromatic heterocyclic ring.

Examples of the heterocycles include nitrogen-containing heterocycles and oxygen-containing heterocycles. Nitrogen-containing heterocycles include monocyclic rings such as pyridine ring and pyridinium ring; polycyclic condensed rings such as quinoline ring, isoquinoline ring and indole ring; and polycyclic ring assembly rings such as bipyridinium ring. Oxygen-containing heterocycles include oxygen-containing aromatic heterocycles such as a pyrylium ring and a pyrylinium ring.

In addition, it is preferable that the heteroatom is not substituted with a protic hydrogen atom. For example, it is preferable that all hydrogen atoms constituting an onium ion such as a pyridinium cation are substituted with substituents other than hydrogen atoms. Examples of the substituent that substitutes on the heteroatom include the substituents exemplified in the section on the anion moiety, and a representative substituent is a hydrocarbon group.

Moreover, when the cation moiety has a heterocyclic ring, the heterocyclic ring may have a substituent. Examples of the substituent to be substituted on the heterocyclic ring include the substituents exemplified in the section on the anion moiety, such as a hydrocarbon group. Substituents may also be substituted or unsubstituted heterocycles. Further, the substituents may be attached to the heterocycle singly or in combination of two or more.

Specific preferred cation moieties include cations having an iodine atom, cations having a nitrogen atom-containing heterocyclic skeleton, and cations having an oxygen atom-containing heterocyclic skeleton. Cations with backbones are particularly preferred.

Examples of cations having an iodine atom include the following formula (3);

(In the formula, Ar ⁴ and Ar ⁵ are aromatic groups optionally having substituents, and the substituents are preferably the groups exemplified above, more preferably alkyl groups. The alkyl group is preferably a group having 2 to 30 carbon atoms, and may be linear, branched, or cyclic. Ar ⁴ and Ar ⁵ may be different from each other or may have the same structure.
Specific examples include cations having a diphenyliodonium skeleton and a bis(alkylphenyl)iodonium cation skeleton. That is, examples of the cation moiety include diphenyliodonium cations and bis(alkylphenyl)iodonium cations.

Examples of cations having a nitrogen atom-containing heterocyclic skeleton include the following formula (4);

(Wherein, the ring structure moiety containing N ⁺ is a 1- to 3-membered cationic heteroaryl group that may contain other heteroatoms in addition to the cationic nitrogen atom, for example, N-substituted It forms a pyridinium skeleton, an N-substituted bipyridinium skeleton, an N-substituted quinolinium skeleton, an N-substituted isoquinolinium skeleton, etc. R ¹ and R ² represent an alkyl group or an aryl group, and the alkyl group and the aryl group have a number of carbon atoms. It is preferably a group of 2-30, and may be linear, branched, cyclic, etc.). Specific examples of cation moieties include N-substituted pyridiniums, N-substituted bipyridiniums, N-substituted quinoliniums, and N-substituted isoquinoliniums.
N-substituted pyridiniums include N-substituted-arylpyridinium such as 4-phenyl-1-n-propylpyridinium, 4-phenyl-1-n-butylpyridinium, 4-phenyl-1-benzylpyridinium; 4-benzoyl and N-substituted-arylcarbonylpyridinium such as -1-benzylpyridinium. N-substituted bipyridiniums include N,N'-dialkylbipyridinium such as 1,1'-dioctyl-4,4'-bipyridinium. N-substituted quinoliniums include N-alkylquinoliniums such as 1-ethylquinolinium. N-substituted isoquinoliniums include N-alkylisoquinoliniums such as 2-n-butylisoquinolinium.

Examples of cations having a sulfur atom include the following formula (5);

(In the formula, Ar ⁶ , Ar ⁷ and Ar ⁸ are aromatic groups optionally having substituents, and the substituents are preferably the groups exemplified above, more preferably alkyl groups The alkyl group is preferably a group having 2 to 30 carbon atoms, and may be linear, branched, or cyclic. Ar ⁶ , Ar ⁷ and Ar ⁸ may be different from each other or may have the same structure.
Specific examples include cations having a triphenylsulfonium skeleton, a tris(alkylphenyl)sulfonium cation skeleton, and a diphenyl[4-(phenylthio)phenyl]sulfonium cation skeleton. That is, examples of cation moieties include diphenyl(4-phenylthiophenyl)sulfonium cations.

Among the above specifically preferred cation moieties, bis(alkylphenyl)iodonium cations are particularly preferred in terms of reactivity and solubility.

A compound having an anion moiety and a cation moiety can be produced by reacting the anion moiety and the cation moiety, and the reaction can be carried out by a conventional method. For example, a salt of an anion portion represented by a complex salt such as sodium salt, potassium salt, sodium/dimethoxyethane salt, and a salt of a cation portion represented by a salt with a halogen such as bromine are reacted in an appropriate solvent. It may be manufactured by The anion moiety and the cation moiety can also be produced by a conventional method, and if commercially available products are available, the commercially available products may be used.

The photo Lewis acid generator for chemically amplified resists of the present invention may contain the compound of the present invention having an anion moiety and a cation moiety, and may be other photoacid generators within a range that does not impair the effects of the present invention. It may contain a drug. The content of the compound having an anion moiety and a cation moiety in the optical Lewis acid generator for chemically amplified resists of the present invention may be, for example, 10 to 100% by mass. In addition, the chemically amplified optical Lewis acid generator of the present invention may contain a solvent, an additive, and the like, which will be described later.

The photo-Lewis acid generator for chemically amplified resists of the present invention contains a compound having an anion moiety and a cation moiety. All combinations of anionic and cationic moieties are included.

In the photo-Lewis acid generator for chemically amplified resists of the present invention, the light capable of generating Lewis acid is not particularly limited. EB), preferably extreme ultraviolet (EUV).

<Composition for chemically amplified resist>
The chemically amplified resist composition of the present invention contains the photo-Lewis acid generator for chemically-amplified resists and a polymerizable compound polymerizable by the photo-Lewis acid generator. By including the photo-Lewis acid generator of the present invention, acid diffusion is sufficiently suppressed when patterning of the resist composition, and a resist pattern with improved roughness can be formed.
The polymerizable compound includes a copolymer of a monomer having a substituent that is decomposed by acid and a monomer having a substituent that is not decomposed or hardly decomposed even in the presence of acid. Examples of monomers having a substituent that is decomposable by acid include monomers having an adamantane skeleton as a substituent, such as 2-(meth)acryloyloxy-2-methyladamantane and 2-(meth)acryloyloxy-2-ethyladamantane. , 1-methylcyclopentyl (meth)acrylate, 1-methylcyclohexyl (meth)acrylate, and other monomers having a cyclic hydrocarbon skeleton as a substituent.
Examples of monomers having substituents that do not decompose or are difficult to decompose even in the presence of acids include monomers having a norbornane skeleton as a substituent such as isobornyl (meth)acrylate, mevalonic acid lactone (meth)acrylate, β-(meth) Examples thereof include monomers having a lactone ring as a substituent such as acryloyloxy-γ-butyrolactone.
Among the above polymerizable compounds, a mixture of a monomer having an adamantane skeleton as a substituent and a monomer having a lactone ring as a substituent is preferable from the standpoint of dry etching resistance and resolution. In addition, you may use a polymerizable compound individually or in combination of 2 or more types.

In the chemically amplified resist composition, the content of the photo-Lewis acid generator is, for example, 0.001 to 20 parts by mass, preferably 0.01 to 10 parts by mass, relative to 100 parts by mass of the polymerizable compound. , and more preferably about 0.1 to 5 parts by mass. In addition, the chemically amplified resist composition of the present invention may further contain other known acid generators, solvents, and additives, if necessary, to the extent that the effects of the present invention are not impaired.

Examples of solvents include esters such as propylene glycol methyl ether acetate, ethyl lactate, methyl-3-methoxypropionate, ethyl pyruvate, and butyl acetate, propylene glycol monomethyl ether, propylene glycol n-propyl ether, and the like. Ethers are mentioned. Examples of additives include sensitizers, pigments, antifoaming agents, stabilizers, antioxidants, surfactants and the like. In addition, you may use a solvent and an additive individually or in combination of 2 or more types. When the chemically amplified resist composition contains a solvent, the solid content in the composition may be, for example, about 0.01 to 50% by weight, preferably about 0.1 to 30% by weight.

By irradiating the chemically amplified resist composition of the present invention with light capable of generating Lewis acid, it is possible to make the exposed area and the unexposed area different in solubility in an alkaline developer. The above-described light irradiation time can be appropriately selected according to the type of light source, and is not particularly limited.

<Method of forming a photoresist pattern>
In the chemically amplified resist composition of the present invention, the action of the Lewis acid generated from the photo-Lewis acid generator upon exposure dissociates the polymer component, mainly the acid-decomposable substituent, to generate a carboxyl group. . As a result, the solubility of the exposed portion in the alkaline developer increases, and the exposed portion is dissolved and removed by the alkaline developer to form a resist pattern.

In order to form a pattern using the chemically amplified resist composition of the present invention, a known lithography technique or a modified technique thereof can be employed. For example, the chemically amplified resist composition of the present invention is coated on a substrate to form a resist film, and after heat treatment (pre-baking), a predetermined portion of the resist film is irradiated with high-energy rays, exposed, and after exposure, After heating (PEB), development may be performed using a developer to form a resist pattern. If necessary, some additional steps such as a water washing step may be added. As a method for applying the composition of the present application onto a substrate, a known method such as spin coating or printing by an inkjet method or the like can be applied. The pre-baking step is a step of removing the solvent and the like contained in the composition, and is usually performed under heating conditions, preferably at about 40 to 250° C., for example. The pre-baking step can be performed under normal pressure conditions, but may be performed under reduced pressure conditions or pressurized conditions. The developer used in the development step is preferably an alkaline solution, preferably an aqueous solution of potassium hydroxide, sodium hydroxide, or tetramethylammonium hydroxide. The above development step may be performed at room temperature, or under cooling or heating conditions. The developer may be used at room temperature, or may be added after cooling or heating.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited only to these Examples. Unless otherwise specified, "part" means "mass part" and "%" means "mass %".

[Production Example 1] Synthesis of base polymer In a nitrogen atmosphere flask, 1.21 g of mevalonic acid lactone methacrylate, 1.42 g of 2-methacryloyloxy-2-methyladamantane, and 0.142 g of an organic peroxide (Arkema Yoshitomi Co., Ltd.) 6.14 g of propylene glycol monomethyl ether acetate (PGMEA) manufactured by Luperox 575) was weighed and stirring was started. The mixture was heated to 90°C with stirring, and stirring was continued for 4 hours while maintaining the temperature at 90°C. After cooling to 50° C., 4.04 g of tetrahydrofuran (THF) was added. After the addition of THF, the reaction solution was cooled to room temperature and added dropwise to 150 g of methanol to precipitate a polymer. After stirring for a while, the polymer was separated by filtration, washed with methanol, and dried under reduced pressure to obtain a 1:1 copolymer of mevalonic acid lactone methacrylate and 2-methacryloyloxy-2-methyladamantane (Mw = 21441, Mw /Mn=2.51) was obtained in an amount of 1.95 g.

[Production Example 2] Synthesis of photo-Lewis acid generator/PGMEA solution Tris(pentafluorophenyl)borane/water complex 10.0 g (manufactured by Nippon Shokubai Co., Ltd., tris(pentafluorophenyl)borane component 90%), Special table 2000 -510516/6.56 g of cumen-4-yl(p-tolyl)iodonium chloride obtained by synthesizing with reference to Example 3, 1.12 g of sodium carbonate, 22.0 g of PGMEA, and 22.0 g of water were added, and the mixture was stirred at room temperature. Stirred for 1 hour. After that, stirring was stopped to separate oil and water to obtain an organic layer. After washing with 20.0 g of water, water was discharged out of the system together with PGMEA by simple distillation of the organic layer. PGMEA was added so that the solid content (iodonium salt) was 50 wt % to obtain a photo-Lewis acid generator/PGMEA solution. The structure of the photo-Lewis acid generator is shown in formula (6) below.

[Example 1] Preparation of chemically amplified resist composition 100 parts by weight of the base polymer obtained in Production Example 1, 10 parts by weight of the photo-Lewis acid generator/PGMEA solution obtained in Production Example 2 (5 parts by weight as iodonium salt) part) and 400 parts by mass of ethyl pyruvate were dissolved to prepare a resist composition.

[Example 2] Exposure evaluation The chemically amplified resist composition obtained in Example 1 was dropped on a glass substrate and applied by spin coating (3000 rpm/30 seconds). A pre-baking process was performed at 90° C. for 5 minutes to form a thin film having a thickness of approximately 1 μm. After UV irradiation (high-pressure mercury lamp/365 nm, 200 mJ/cm ² ), post-exposure heating (PEB) was performed at 130° C. for 10 minutes. Then, it was cooled to room temperature, developed with a 0.05% KOH aqueous solution for 20 seconds, and washed with pure water. Observation of the coating film after drying revealed that the thin film formed by the chemically amplified resist composition had been completely removed from the exposed portions.

[Example 3] Acid diffusibility evaluation (Lewis acid)
100 parts by mass of the base polymer obtained in Production Example 1 was dissolved in 1500 parts by mass of ethyl pyruvate to prepare a resist composition. This resin composition was dropped onto a glass substrate and applied by spin coating (3000 rpm/30 seconds). A pre-baking process was performed at 90° C. for 5 minutes to form a resin thin film having a thickness of approximately 0.2 μm.
Furthermore, 100 parts by mass of the base polymer obtained in Production Example 1, 10 parts by mass of the optical Lewis acid generator/PGMEA solution obtained in Production Example 2 (5 parts by mass as an iodonium salt), and 1500 parts by mass of ethyl pyruvate are dissolved. Then, a resist composition was separately prepared. This resist composition was dropped onto the resin thin film of the glass substrate prepared above and applied by spin coating (3000 rpm/30 seconds). It was treated at 90° C. for 5 minutes as a pre-bake.
In the same manner as in Example 2, after UV irradiation (high-pressure mercury lamp/365 nm, 200 mJ/cm ² ), post-exposure heating (PEB) was performed at 130° C. for 10 minutes. Then, it was cooled to room temperature, developed with a 0.05% KOH aqueous solution for 20 seconds, and washed with pure water. When the dried product was observed, a thin film remained even in the exposed portion.

[Comparative Example 1] Evaluation of acid diffusibility (protonic acid)
In Production Example 2, by changing the photo-Lewis acid generator to a photo-proton acid generator represented by an iodonium salt (PAG-1/TEPBI) having a structure shown in the following formula (7), a proton acid generator/ A PGMEA solution was obtained. The same operation as in Example 3 was performed except that the solution on the left was changed. Observation of the dried product after development revealed that the exposed portion, including the first resist film containing no PAG-1, had been completely removed, exposing the glass substrate.

From Example 3 and Comparative Example 1, the use of the chemically amplified photo-Lewis acid generator of the present invention was found to be effective in suppressing acid diffusivity, so pattern formation with improved roughness can be expected.

Claims (3)

The anion part is represented by the following general formula (1), and the cation part is represented by the following general formula (3) or the following general formula (4). except).

(wherein Ar ¹ to Ar ³ are an aryl group or an optionally substituted aryl group, and Y is a hydroxyl group. Ar ¹ to Ar ³ may be the same or different. good.)

(In the formula, Ar ⁴ and Ar ⁵ are aromatic groups optionally having substituents, and the substituents are alkyl groups having 2 to 30 carbon atoms.)

(Wherein, the ring structure moiety containing N ⁺ is a cationic heteroaryl group with a 1- to 3-membered ring that may contain other heteroatoms in addition to the cationic nitrogen atom, and R ¹ , R ² represents an alkyl group or an aryl group, and the alkyl group or aryl group is a group having 2 to 30 carbon atoms.) 2. A photo Lewis acid generator for a chemically amplified resist, wherein the chemically amplified resist according to claim 1 is positive (excluding protonic acid). 3. A composition for a chemically amplified resist, comprising the photo Lewis acid generator for a chemically amplified resist according to claim 1 or 2 (excluding protonic acid).