JP7658255B2 - Resist Composition - Google Patents

Description

The present invention relates to a resist composition. More specifically, the present invention relates to a resist composition, a resist film, a pattern forming method, and a method for manufacturing an electronic device that are suitable for lithography using radiation such as electron beams and extreme ultraviolet rays.

In recent years, in the field of microfabrication of semiconductor devices such as ICs and LSIs, the increasing integration of integrated circuits has led to a demand for the formation of fine patterns in the submicron and quarter-micron regions. Accordingly, the exposure wavelength has also become shorter, from g-line to i-line, KrF excimer laser light, and ArF excimer laser light. Recently, development of lithography techniques using radiation such as electron beams (EB) and extreme ultraviolet rays (EUV) other than excimer laser light has also been progressing (Patent Document 1).

Lithography technology using the above-mentioned radiation is expected to be the next-generation pattern technology capable of forming ultra-fine patterns with widths of a few nm. However, exposure using this radiation has the drawback of low throughput due to the low power of the exposure light source, which is a major issue. To solve this issue, improvements to the equipment, such as increasing the output of the light source, are being considered, while there is also a demand for higher sensitivity in lithography resist resins.

The use of metal oxide particles has been considered as a method for increasing sensitivity (Patent Document 2). In this method, metal oxide nanoparticles with a particle size of 20 nm or less absorb radiation, and secondary electrons are generated from polymers and the like in the resist composition. The secondary electrons are absorbed by a photoacid generator, which further promotes the decomposition of the photoacid generator, thereby functioning as an excellent positive photoresist.
However, the photoresist composition of Patent Document 2 has a problem in that the efficiency of absorbing radiation gradually decreases due to aggregation of metal oxide nanoparticles.

In order to solve the above problems, the addition of an aggregation inhibitor has been considered, but the reality is that sufficient dispersion stability and sensitivity are not obtained (Patent Document 3).
In addition, the development of a radiation photoresist using a metal complex instead of metal oxide nanoparticles that cause particle aggregation is also being considered (Patent Document 4). The negative photoresist composition of Patent Document 4 is a mixture of a metal complex compound consisting of an alkoxide of zirconium or hafnium and a methacrylic acid compound, and a photopolymerization initiator, and the metal complex absorbs EUV, making the exposed areas insoluble in an organic developer, thereby obtaining a resist pattern in which the unexposed areas have been removed.
However, the composition of Patent Document 4 does not provide sufficient radiation absorption efficiency, and the efficiency of transfer of secondary electrons generated from the metal part to the photopolymerization initiator is insufficient, so that satisfactory sensitivity cannot be obtained.
As described above, for photoresist compositions for EB or EUV, there is a demand for the development of compositions that have even higher sensitivity and are suitable for producing ultrafine patterns in order to improve throughput.

JP 2006-171440 A WO2016/088655 WO2017/204090 JP 2015-108781 A

The object of the present invention is to provide a resist composition with high absorption sensitivity not found in conventional photoresist compositions for radiation such as EB and EUV.

As a result of intensive research to solve the above problems, the inventors discovered that a metal complex obtained from a carboxylic acid-containing trinuclear monomer and a metal alkoxide has high EB and EUV absorption properties, and that it efficiently transfers electrons to a photoacid generator, and the generated acid forms a crosslinked structure between a polyfunctional methylol crosslinker and the trinuclear monomer, resulting in a resist film with high radiation absorption sensitivity, thus completing the present invention.

［式（１）中、Ｒ^１及びＲ^２は、それぞれ独立に、炭素原子数１～９の脂肪族炭化水素基、アルコキシ基、アリール基、アラルキル基又はハロゲン原子を表す。ｍ、ｎ及びｐは、それぞれ独立に、０～４の整数を表す。Ｒ^１が複数ある場合、複数のＲ^１は互いに同じでも異なってもよい。Ｒ^２が複数ある場合、複数のＲ^２は互いに同じでも異なってもよい。Ｒ^３は、水素原子、炭素原子数１～９の脂肪族炭化水素基、又は炭化水素基上にアルコキシ基、ハロゲン基及び水酸基から選択される置換基を１以上有する構造部位を表す。Ｒ^４は、水酸基、炭素原子数１～９の脂肪族炭化水素基、アルコキシ基又はハロゲン原子を表す。Ｒ^４が複数ある場合、複数のＲ^４は互いに同じでも異なってもよい。］ That is, the present invention relates to a resist composition comprising the following components (A) to (E):
(A) a phenol trinuclear monomer represented by the following formula (1): (B) a metal alkoxide; (C) a photoacid generator; (D) a polyfunctional methylol crosslinking agent; and (E) a solvent.

[In formula (1), R ¹ and R ² each independently represent an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom. m, n, and p each independently represent an integer of 0 to 4. When there are multiple R ^1s , the multiple R ^1s may be the same as or different from each other. When there are multiple R ^2s , the multiple R ^2s may be the same as or different from each other. R ³ represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, or a structural portion having one or more substituents selected from an alkoxy group, a halogen group, and a hydroxyl group on a hydrocarbon group. R ⁴ represents a hydroxyl group, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, or a halogen atom. When there are multiple R ^4s , the multiple R ^4s may be the same as or different from each other.]

The present invention also relates to a resist film obtained from the above resist composition.
The present invention also relates to a pattern forming method, comprising the steps of forming a resist film using the above resist composition, exposing the resist film to light, and developing the exposed resist film with a developer to form a pattern.
The present invention also relates to a method for producing an electronic device, which includes the above-mentioned pattern forming method.

The present invention provides a resist composition that has high absorption sensitivity to radiation such as EB and EUV.

1 is a GPC chart of the phenol trinuclear monomer (A) synthesized in Example 1. 1 is a ¹³ C-NMR chart of the phenol trinuclear monomer (A) synthesized in Example 1. 1 is an FT-IR spectrum of the metal complex solution prepared in Example 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the invention.
In this specification, "x to y" represents a numerical range of "not less than x and not more than y." The upper and lower limit values described in relation to the numerical ranges can be combined in any combination.
In addition, any combination of two or more of the individual aspects of the present invention described below is also an aspect of the present invention.

［式（１）中、Ｒ^１及びＲ^２は、それぞれ独立に、炭素原子数１～９の脂肪族炭化水素基、アルコキシ基、アリール基、アラルキル基又はハロゲン原子を表す。ｍ、ｎ及びｐは、それぞれ独立に、０～４の整数を表す。Ｒ^１が複数ある場合、複数のＲ^１は互いに同じでも異なってもよい。Ｒ^２が複数ある場合、複数のＲ^２は互いに同じでも異なってもよい。Ｒ^３は、水素原子、炭素原子数１～９の脂肪族炭化水素基、又は炭化水素基上にアルコキシ基、ハロゲン基及び水酸基から選択される置換基を１以上有する構造部位を表す。Ｒ^４は、水酸基、炭素原子数１～９の脂肪族炭化水素基、アルコキシ基又はハロゲン原子を表す。Ｒ^４が複数ある場合、複数のＲ^４は互いに同じでも異なってもよい。］ A resist composition according to one embodiment of the present invention contains the following components (A) to (E).
(A) a phenol trinuclear monomer represented by the following formula (1): (B) a metal alkoxide; (C) a photoacid generator; (D) a polyfunctional methylol crosslinking agent; and (E) a solvent.

[In formula (1), R ¹ and R ² each independently represent an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom. m, n, and p each independently represent an integer of 0 to 4. When there are multiple R ^1s , the multiple R ^1s may be the same as or different from each other. When there are multiple R ^2s , the multiple R ^2s may be the same as or different from each other. R ³ represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, or a structural portion having one or more substituents selected from an alkoxy group, a halogen group, and a hydroxyl group on a hydrocarbon group. R ⁴ represents a hydroxyl group, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, or a halogen atom. When there are multiple R ^4s , the multiple R ^4s may be the same as or different from each other.]

In this embodiment, the metal complex obtained from the above components (A) and (B) has high radiation absorption properties and efficiently transfers electrons to the photoacid generator (component (C)). The acid thus generated forms a crosslinked structure between the polyfunctional methylol crosslinker (component (D)) and component (A), thereby obtaining a resist composition (resist film) having high radiation sensitivity.
Components (A) to (E) will be described below.

Component (A): Phenol trinuclear monomer represented by formula (1) In the above phenol trinuclear monomer represented by formula (1), ^R1 and ^R2 in formula (1) each independently represent an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom. The aliphatic hydrocarbon group may be linear or may have a branched structure. It may also have a cyclocyclic structure.
More specific examples of the alkoxy group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a t-butyl group, a hexyl group, a cyclohexyl group, a heptyl group, an octyl group, a nonyl group, etc. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propyloxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a cyclohexyloxy group, etc.

Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group.
Examples of the aralkyl group include a benzyl group, a phenylethyl group, a phenylpropyl group, and a naphthylmethyl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Among these, R ¹ and R ² are preferably alkyl groups having 1 to 4 carbon atoms, and particularly preferably methyl groups, because they are excellent in the ability to form fine patterns when used as a resist material.
In addition, m and n in formula (1) are integers of 0 to 4, and are more preferably integers of 1 to 3, and particularly preferably 2. In this case, it is preferable that the two ^R1s and the two ^R2s are bonded to the 2,5-positions of the phenolic hydroxyl group, respectively.

In formula (1), ^R3 represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, or a structural portion having, on a hydrocarbon group, one or more substituents selected from an alkoxy group, a halogen group, and a hydroxyl group.
Examples of the aliphatic hydrocarbon group having 1 to 9 carbon atoms include those exemplified as ^R1 and ^R2 . Examples of the "structural portion having one or more substituents selected from an alkoxy group, a halogen group, and a hydroxyl group on the hydrocarbon group" include a halogenated alkyl group, a halogenated aryl group, an alkoxyalkoxy group such as a 2-methoxyethoxy group or a 2-ethoxyethoxy group, an alkylalkoxy group substituted with a hydroxy group, etc. Of these, it is preferable that ^R3 is a hydrogen atom.

In formula (1), ^R4 represents a hydroxyl group, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, or a halogen atom. Specific examples of each include those exemplified for ^R1 and ^R2 .
Furthermore, p represents an integer of 0 to 4. Among these, p is preferably 0.

In this embodiment, component (A) may be a single compound having the same structure, or multiple compounds having different molecular structures.

Component (A) may be produced by any method. For example, it can be obtained by heating a phenol compound (a1) and a formylbenzoic acid (a2) in the presence of an acid catalyst, optionally using a solvent, at a temperature in the range of 60 to 140°C to polycondense them.

The phenol compound (a1) may be a compound having one or more substituents such as an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom on the aromatic ring of the phenol, in addition to phenol. Specific examples of these substituents include those exemplified as R ¹ and R ² in the above formula (1). Among them, it is preferable that the compound has one to three alkyl groups having 1 to 4 carbon atoms, and particularly preferably has two alkyl groups having 1 to 4 carbon atoms, because the compound has excellent ability to form a fine pattern when used as a resist material. In this case, it is preferable that the two alkyl groups are bonded to the 2,5-positions of the phenolic hydroxyl group, respectively. In addition, the alkyl group is particularly preferably a methyl group.

Examples of the formylbenzoic acids (a2) include formylbenzoic acid, compounds having one or more hydroxyl groups, aliphatic hydrocarbon groups having 1 to 9 carbon atoms, alkoxy groups, or halogen atoms on the aromatic ring thereof, aromatic ketones having a carboxy group such as acetylbenzoic acid, and compounds having one or more hydroxyl groups, aliphatic hydrocarbon groups having 1 to 9 carbon atoms, alkoxy groups, or halogen atoms on the aromatic ring thereof.
Specific examples of the aliphatic hydrocarbon group having 1 to 9 carbon atoms, the alkoxy group, or the halogen atom include those exemplified as R ⁴ in the above formula (1). Among them, formylbenzoic acid is preferred because of its excellent reactivity with the phenol compound (a1), and 4-formylbenzoic acid is more preferred because it has a molecular structure that is easily coordinated to a metal atom.

Examples of acid catalysts used in the production of component (A) include acetic acid, oxalic acid, sulfuric acid, hydrochloric acid, phenolsulfonic acid, paratoluenesulfonic acid, zinc acetate, manganese acetate, etc. These acid catalysts can be used alone or in combination of two or more. Among these acid catalysts, sulfuric acid and paratoluenesulfonic acid are preferred because of their excellent activity. The acid catalysts can be added before or during the reaction.

When a solvent is used in the production of component (A), specific examples include carboxylic acid compounds such as formic acid, acetic acid, propionic acid, butyric acid, and valeric acid; glycol ether compounds such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monopentyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl methyl ether, and ethylene glycol monophenyl ether; cyclic ether compounds such as 1,3-dioxane and 1,4-dioxane; glycol ester compounds such as ethylene glycol acetate; ketone compounds such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and aromatic hydrocarbons such as toluene and xylene. These solvents can be used alone or in combination of two or more. Among these solvents, acetic acid is preferred because of its excellent solubility in the resulting compound.

The charging ratio [(a1)/(a2)] of the phenol compound (a1) to the formylbenzoic acids (a2) is preferably in the range of 1/0.8 to 1/0.2 in molar ratio, more preferably 1/0.6 to 1/0.4, because this allows for excellent removal of unreacted phenol compound (a1) and excellent yield and purity of the resulting compound (a).

After the reaction is completed, the component (A) can be purified and isolated by, for example, pouring the reaction solution into a poor solvent (S1) in which the reaction product is insoluble or poorly soluble, filtering off the resulting precipitate to obtain a crude product, redissolving the crude product in a solvent (S2) that is also miscible with the poor solvent (S1) and can dissolve the reaction product, pouring the crude product back into the poor solvent (S1), and filtering off the resulting precipitate. In addition, when an aromatic hydrocarbon such as toluene or xylene is used as the reaction solvent, the product component (A) dissolves in the solvent by heating at 80°C or higher, and by cooling as is, crystals of component (A) precipitate, which can be filtered off to isolate component (A). In this case, it is not necessary to use the poor solvent (S1) and the solvent (S2).

Examples of poor solvents (S1) include water; monoalcohols such as methanol, ethanol, and propanol; aliphatic hydrocarbons such as n-hexane, n-heptane, n-octane, and cyclohexane; and aromatic hydrocarbons such as toluene and xylene. Among these poor solvents (S1), water and methanol are preferred because they can efficiently remove the acid catalyst at the same time.

Examples of the solvent (S2) include monoalcohols such as methanol, ethanol, and propanol; polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, trimethylene glycol, diethylene glycol, polyethylene glycol, and glycerin; glycol ethers such as 2-ethoxyethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monopentyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl methyl ether, and ethylene glycol monophenyl ether; cyclic ethers such as 1,3-dioxane and 1,4-dioxane; glycol esters such as ethylene glycol acetate; and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.
When water is used as the poor solvent (S1), acetone is preferred as the solvent (S2). The poor solvent (S1) and the solvent (S2) may each be used alone or in combination of two or more kinds.

The purity of component (A) is preferably 90% or more, more preferably 94% or more, and particularly preferably 98% or more, as calculated from a gel permeation chromatography (GPC) chart. The GPC measurement conditions are as described in the Examples.

Component (B): Metal Alkoxide A metal alkoxide is a metal complex having ^RO- (R is a hydrocarbon group having 1 to 22 carbon atoms) as a ligand, and when mixed with component (A), ligand exchange occurs, and a metal complex having component (A) as a ligand can be formed. By using a metal alkoxide, a resist film with excellent photosensitivity and alkali solubility can be obtained.
R is preferably a hydrocarbon group having 2 to 6 carbon atoms, specifically, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an isobutyl group, an s-butyl group, an n-pentyl group, a neopentyl group, an s-pentyl group, an isopentyl group, a t-pentyl group, various hexyl groups, and the like.

Examples of the central metal of the metal alkoxide include magnesium, aluminum, calcium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, silver, cadmium, indium, tin, antimony, cesium, and hafnium. Among these, zirconium, tin, and hafnium are preferred. The valence of the central metal is not particularly limited, and the complex may have any valence.
The metal alkoxide may be used alone or in combination of two or more kinds.

The mixing ratio of component (A) and component (B) is preferably in the range of 0.5 to 10 moles of component (A) per mole of the central metal of component (B), and more preferably in the range of 2 to 6 moles, in order to fully exert the effects of the present invention.

Component (C): Photoacid generator Examples of the photoacid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. Among these, onium salt compounds are preferred.
Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

Examples of sulfonium salts include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium Phenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, triphenylsulfonium 2-(1-adamantyl)-1,1-difluoroethanesulfonate, triphenylsulfonium Examples include triphenylsulfonium 6-(1-adamantylcarbonyloxy)-1,1,2,2-tetrafluorohexane-1-sulfonate, triphenylsulfonium 6-(1-adamantylcarbonyloxy)-1,1,2-trifluorobutane-1-sulfonate, triphenylsulfonium 2-(4-oxo-1-adamantylcarbonyloxy)-1,1,3,3,3-pentafluoropropane-1-sulfonate, and triphenylsulfonium 2-bicyclo[2.2.1]hept-2-yl-1,1-difluoroethanesulfonate.

Tetrahydrothiophenium salts include 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium trifluoromethanesulfonate, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium perfluoro-n-octanesulfonate, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium 2-bicyclo[2.2. 1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium camphorsulfonate, 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium trifluoromethanesulfonate, 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium perf 1-(6-n-butoxynaphthalene-2-yl)tetrahydrothiophenium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1-(6-n-butoxynaphthalene-2-yl)tetrahydrothiophenium camphorsulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium trifluoromethanesulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium trifluoromethanesulfonate, Examples include hydrothiophenium nonafluoro-n-butanesulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium perfluoro-n-octanesulfonate, 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium 2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, and 1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium camphorsulfonate.

Among the onium salt compounds, sulfonium salts are preferred, and triarylsulfonium salts are more preferred. For example, the following triarylsulfonium is preferred. Examples of the anion include SbF ₆ , PF ₆ , and B(C ₆ F ₅ ) ₄ .

The content of component (C) is preferably 1 to 50 mass% of the solid content of the resist composition, and more preferably 5 to 20 mass%. The solid content of the resist composition means the total of all components in the resist material other than the solvent.

Component (D): Polyfunctional methylol crosslinking agent The polyfunctional methylol compound may be any compound having two or more methylol groups. Specific examples thereof include the following compounds.

（式（２）中、Ｒａは炭素原子数１～９の脂肪族炭化水素基、アルコキシ基又はハロゲン原子を表す。ｑは２～４の整数であり、ｒは０～３の整数であり、ｓは１～４の整数を表す。Ｒａが複数ある場合、複数のＲａは互いに同じでも異なってもよい。） In one embodiment, the polyfunctional methylol compound is preferably a compound represented by the following formula (2).

(In formula (2), Ra represents an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, or a halogen atom. q represents an integer of 2 to 4, r represents an integer of 0 to 3, and s represents an integer of 1 to 4. When there are multiple Ra's, the multiple Ra's may be the same or different from each other.)

Examples of aliphatic hydrocarbon groups having 1 to 9 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, hexyl, cyclohexyl, heptyl, octyl, and nonyl groups. Examples of alkoxy groups include methoxy, ethoxy, propyloxy, butoxy, pentyloxy, hexyloxy, and cyclohexyloxy groups. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

In one embodiment, s in formula (2) is preferably 1. Also, r is preferably 1. Also, q is preferably 2.

The component (D) may be used alone or in combination of two or more types.
The amount of component (D) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the total of components (A) and (B), in order to obtain good sensitivity and a desired pattern, and is preferably 30 parts by mass or less, more preferably 15 parts by mass or less.

Component (E): Solvent The solvent is not particularly limited as long as it can dissolve the above-mentioned components (A) and (B). Specific examples include monoalcohols such as methanol, ethanol, propanol, and butanol; polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, trimethylene glycol, diethylene glycol, polyethylene glycol, and glycerin; glycol ethers such as 2-ethoxyethanol, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monopentyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl methyl ether, ethylene glycol monophenyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether; methylcello propylene glycol alkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate; cyclic ethers such as tetrahydrofuran, 1,3-dioxane, 1,4-dioxane; glycol esters such as ethylene glycol acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; ester compounds such as methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl oxyacetate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, ethyl formate, ethyl acetate, butyl acetate, methyl acetoacetate, and ethyl acetoacetate; and nitrile compounds such as acetonitrile, acrylonitrile, propionitrile, and butyronitrile.
The solvent may be used alone or in the form of a mixture of two or more kinds.

The amount of component (E) used is not particularly limited and is adjusted appropriately depending on the specific application. In particular, it is preferable that the solids concentration in the resist composition is in the range of 0.1 to 50 mass %, since this allows a uniform film thickness to be obtained when applying the composition by a method such as spin coating.

In addition to the above-mentioned components (A) to (E), the resist composition of this embodiment may contain known additives, such as a curing agent, a photosensitizer, a filler, a pigment, a surfactant such as a leveling agent, an adhesion improver, a dissolution promoter, etc., as necessary. When additives are added, the effect of the present invention is fully exhibited, so that the ratio of components (A) and (B) to the total weight of the components other than component (E) of the resist composition is preferably 50% by weight or more, more preferably 75% by weight or more, and particularly preferably 90% by weight or more.

The resist composition of this embodiment can be prepared by mixing and stirring the above-mentioned components (A) to (E) and, if necessary, additives. The mixing order of each component is not particularly limited. In one embodiment, the above-mentioned components (A) and (B) may be mixed in a solvent to prepare a metal complex solution, and then other components may be added. As the solvent, the same one as the above-mentioned component (E) can be used.
The amount of the solvent used is not particularly limited, but is preferably in the range of 1 to 500 parts by mass per part by mass of the total of components (A) and (B).
The temperature conditions when components (A) and (B) are mixed are not particularly limited, and may be room temperature of about 20 to 25° C., or may be appropriately heated as necessary.
The formation of the metal complex can be confirmed, for example, from a peak at 1400 cm ⁻¹ in an IR spectrum.

When the resist composition of this embodiment contains solids such as fillers, pigments, etc., it is preferable to disperse and mix using a dispersing device such as a dissolver, homogenizer, or triple roll mill. In addition, in order to remove coarse particles and impurities, it is also possible to filter using a mesh filter, membrane filter, etc.

The resist composition of this embodiment can be used for pattern formation in the same manner as general resist materials. One example of such a method includes a process of forming a resist film using the resist composition, a process of exposing the resist film, and a process of developing the exposed resist film with a developer to form a pattern.

In the process of forming the resist film, the coating method is not particularly limited, and any method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor blade coating, etc. may be used. After coating, the solvent, which is component (E), can be removed by pre-baking at a temperature condition of 60 to 150°C to obtain a coating film (resist film). In addition, examples of objects to be coated include silicon substrates, silicon carbide substrates, gallium nitride substrates, transparent conductive films, etc., and can be appropriately selected depending on the application, etc.

In the exposure process, the film is exposed through a mask on which a pattern is drawn. Examples of exposure light sources include infrared light, visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light, X-rays, and electron beams. The resist composition of this embodiment is highly sensitive and can form fine patterns, so it can also be suitably used for exposure to extreme ultraviolet light and electron beams.

The alkaline developer used in the development step can be any of those used in general alkaline development applications. For example, an alkaline aqueous solution of inorganic alkaline substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and cyclic amines such as pyrrole and piheridine can be used. These alkaline developers can also be used by adding alcohol, surfactants, etc. as necessary. The alkaline concentration of the alkaline developer is usually preferably in the range of 2 to 5% by mass, and a 2.38% by mass aqueous solution of tetramethylammonium hydroxide is generally used.

The pattern formation method of the present invention is suitable for use in the manufacturing process of electronic devices. Examples of such electronic devices include household electrical appliances, office automation equipment, media-related equipment, optical equipment, and communication equipment.

The present invention will be described in more detail below with reference to specific examples. The number average molecular weight (Mn), weight average molecular weight (Mw), and polydispersity (Mw/Mn) of the synthesized resins were measured under the following GPC measurement conditions.
[GPC measurement conditions]
Measuring device: "HLC-8220 GPC" manufactured by Tosoh Corporation
Column: Showa Denko K.K. "Shodex KF802": 8.0 mmΦ x 300 mm
+ Showa Denko K.K. "Shodex KF802": 8.0mmΦ x 300mm
+ Showa Denko K.K. "Shodex KF803": 8.0mmΦ x 300mm
+ Showa Denko K.K. "Shodex KF804": 8.0mmΦ x 300mm
Column temperature: 40°C
Detector: RI (differential refractometer)
Data processing: Tosoh Corporation "GPC-8020 Model II Version 4.30"
Developing solvent: tetrahydrofuran Flow rate: 1.0 mL/min Sample: 0.5% by mass (resin solid content) tetrahydrofuran solution filtered through a microfilter Injection amount: 0.1 mL
Standard sample: Monodisperse polystyrene (Standard sample: Monodisperse polystyrene)
"A-500" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
"F-10" manufactured by Tosoh Corporation
"F-20" manufactured by Tosoh Corporation

The measurement conditions for ¹³ C-NMR are as follows.
Equipment: JNM-ECA500 manufactured by JEOL Ltd.
Measurement mode: inverse gated decoupling Solvent: deuterated dimethyl sulfoxide Pulse angle: 30° pulse Sample concentration: 30% by mass
Number of integrations: 4000 Chemical shift standard: Dimethyl sulfoxide peak: 39.5 ppm

Example 1
(1) Synthesis of phenol trinuclear monomer (A) 293.2 g (2.4 mol) of 2,5-xylenol and 150 g (1 mol) of 4-formylbenzoic acid were charged into a 2000 mL four-neck flask equipped with a cooling tube, and dissolved in 500 ml of acetic acid. 5 mL of sulfuric acid was added while cooling in an ice bath, and then the mixture was heated to 100°C with a mantle heater and reacted for 2 hours while stirring. After the reaction was completed, water was added to the obtained solution to precipitate a crude product. Next, the crude product was redissolved in acetone, and water was added to reprecipitate. The precipitate was filtered and dried in vacuum to obtain 292 g of phenol trinuclear monomer (A) as pale pink crystals.

The resulting monomer (A) was confirmed to be a compound represented by the following structural formula by ¹³ C-NMR spectrum measurement. The purity calculated from the GPC chart was 95.3%. The GPC chart of monomer (A) is shown in FIG. 1, and the ¹³ C-NMR chart is shown in FIG. 2.

(2) Preparation of Metal Complex Solution 3.76 g (10 mmol) of the phenol trinuclear monomer (A) obtained in (1) above, 2.308 g (2.52 mmol as Zr element) of zirconium (IV) dibutoxide (Orgatix ZC-580 (manufactured by Matsumoto Fine Chemical Co., Ltd.)), and 24.24 g of tetrahydrofuran (THF) were mixed in a 50 mL screw tube at room temperature for 30 minutes to obtain a metal complex solution.
The FT-IR spectrum of the obtained metal complex solution is shown in FIG.

(3) Preparation of resist composition To the obtained metal complex solution, 0.25 g of a photoacid generator (CPI-101A manufactured by San-Apro Ltd.) and 0.038 g of a polyfunctional methylol crosslinking agent (2,6-Bis(hydroxymethyl)-P-cresol manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was mixed at room temperature for 30 minutes. Thereafter, the mixture was precision-filtered using a polytetrafluoroethylene (PTFE) disk filter having a pore size of 0.1 μm to prepare a resist composition.

Example 2
A resist composition was prepared in the same manner as in Example 1, except that the amount of photoacid generator was changed to 1.25 g, the amount of polyfunctional methylol crosslinking agent was changed to 0.19 g, and the amount of THF was changed to 23.28 g.

Example 3
A resist composition was prepared in the same manner as in Example 1, except that the amount of photoacid generator was changed to 2.51 g, the amount of polyfunctional methylol crosslinking agent was changed to 0.38 g, and the amount of THF was changed to 28.82 g.

Comparative Example 1
A resist composition was prepared in the same manner as in Example 1, except that the photoacid generator and the polyfunctional methylol crosslinking agent were not added and the amount of THF was changed to 23.72 g.

Comparative Example 2
(1) Synthesis of polymerizable group-containing Zr complex In a flask, 0.95 g of zirconium butoxide, 1.27 g of methacrylic acid, and 20 g of dichloromethane as a solvent were stirred for 60 minutes at room temperature of 23° C. The resulting solution was washed with methyl tert-butyl ether (TBME), filtered, and dried under reduced pressure for 5 hours to obtain a zirconia complex.

(2) Preparation of resist composition 1 g of the zirconia complex obtained in (1) above was stirred with 0.1 g of a polymerization initiator (2,2-dimethoxy-2-phenylacetophenone) and 11 g of propylene glycol monomethyl ether in a 30 mL screw tube at room temperature of 23° C. for 5 minutes to prepare a resist composition.

[Contrast evaluation]
The resist compositions prepared in the Examples and Comparative Examples were applied to a silicon wafer having a diameter of 5 inches using a spin coater to a thickness of about 5 μm, and then prebaked at 110° C. for 60 seconds to form a resist film.
The wafer having the resist film was irradiated with an electron beam (EB) at a dose of 500 kGy using an electron beam irradiation device (EES-30L-DIC01, manufactured by Hamamatsu Photonics KK).
The resist film not exposed to EB and the resist film exposed to EB were each subjected to post-exposure bake (PEB) at 130° C. for 90 seconds, followed by paddle development in a tetrahydrofuran solution for 5 seconds, and the wafer was rinsed with pure water for 10 seconds.
The thickness of the resist film on the resulting wafer was evaluated, and the solvent dissolution rate was calculated from the degree of film thickness reduction before and after development using the following formula.
Solvent dissolution rate (Å/Sec)=film reduction rate before and after the solvent (Å)/5 (Sec)

The solvent dissolution rate of the resist film not irradiated with EB was designated as DR1, and the solvent solubility was evaluated as follows. The results are shown in Table 1.
○: DR1 is 2500 or more ×: DR1 is less than 2500

The solvent dissolution rate of the resist film irradiated with EB was designated as DR2, and the negative resist characteristics were evaluated from the contrast value of DR1/DR2 as follows. The results are shown in Table 1.
◯: contrast is 5 or more; ×: contrast is less than 5. It can be said that the higher the contrast, the higher the EB sensitivity.

From Table 1, it can be seen that the resist film obtained from the resist composition of the embodiment example has a high absorption sensitivity to EB because it can obtain a high contrast by EB irradiation compared to the comparative example.

Claims (10)

A resist composition comprising the following components (A) to (E):
(A) a phenol trinuclear monomer represented by the following formula (1): (B) a metal alkoxide; (C) a photoacid generator; (D) a polyfunctional methylol crosslinking agent; and (E) a solvent.

[In formula (1), R ¹ and R ² each independently represent an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom. m, n, and p each independently represent an integer of 0 to 4. When there are multiple R ^1s , the multiple R ^1s may be the same as or different from each other. When there are multiple R ^2s , the multiple R ^2s may be the same as or different from each other. R ³ represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, or a structural portion having one or more substituents selected from an alkoxy group, a halogen group, and a hydroxyl group on a hydrocarbon group. R ⁴ represents a hydroxyl group, an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, or a halogen atom. When there are multiple R ^4s , the multiple R ^4s may be the same as or different from each other.] The resist composition according to claim 1, wherein m and n in formula (1) are each independently an integer of 1 to 3, and p is 0. 3. The resist composition according to claim 1, wherein R ¹ and R ² in the formula (1) are each independently an alkyl group having 1 to 4 carbon atoms, and R ³ is a hydrogen atom. The resist composition according to any one of claims 1 to 3, wherein the component (B) is a metal alkoxide having a central metal selected from the group consisting of zirconium, tin, and hafnium. The resist composition according to any one of claims 1 to 4, wherein component (C) is a sulfonium salt. 6. The resist composition according to claim 1, wherein the component (D) is a compound represented by the following formula (2):

(In formula (2), Ra represents an aliphatic hydrocarbon group having 1 to 9 carbon atoms, an alkoxy group, or a halogen atom. q represents an integer of 2 to 4, r represents an integer of 0 to 3, and s represents an integer of 1 to 4. When there are multiple Ra's, the multiple Ra's may be the same or different from each other.) A resist film obtained from the resist composition according to any one of claims 1 to 6. forming a resist film using the resist composition according to any one of claims 1 to 6;
exposing the resist film to light;
and developing the exposed resist film with a developer to form a pattern. The pattern formation method according to claim 8, wherein the exposure is with an electron beam or extreme ultraviolet light. A method for manufacturing an electronic device, comprising the pattern formation method according to claim 8 or 9.

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