JP2014211541A - Method for forming fine pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a fine pattern by which a resist pattern and an inorganic pattern with small LWR and good features are formed and a good pattern can be formed on a substrate to be processed.SOLUTION: The method for forming a fine pattern of the present invention includes steps of: (1) forming a resist film by applying a photoresist composition on the substrate to be processed; (2) exposing the resist film; (3) forming a negative resist pattern by developing the exposed resist film with a developing solution containing an organic solvent; (4) forming an inorganic layer to cover the resist pattern surface; (5) removing the inorganic layer except for a portion formed on a side wall of the resist pattern by etching back the inorganic layer; and (6) forming an inorganic pattern by removing the resist pattern.

Description

  The present invention relates to a method for forming a fine pattern.

  With higher integration of semiconductor devices and the like, there has been a demand for finer pattern formation than ever before. Particularly recently, formation of a pattern size smaller than the limit resolution in exposure light is required. Various techniques have been studied as techniques that can satisfy this requirement. For example, a resist pattern is first formed on a substrate, an inorganic layer (side wall pattern) is formed on the side surface, and then the resist pattern is removed. A method of forming a fine pattern by processing a substrate to be processed by etching using this inorganic layer as a mask is known (see Japanese Patent Application Laid-Open No. 2009-16814).

  However, although the above conventional method can form a fine pattern, there is a disadvantage that it is difficult to form a good pattern having a highly accurate size and shape on the substrate to be processed. Therefore, a method for forming a good pattern is desired.

JP 2009-16814 A

  The present invention has been made based on the above circumstances, and its purpose is to form a resist pattern and an inorganic pattern having a small LWR and a good shape, and to form a good pattern on a substrate to be processed. Another object is to provide a method for forming a fine pattern.

The invention made to solve the above problems is
(1) A step of applying a photoresist composition on a substrate to be processed to form a resist film,
(2) a step of exposing the resist film;
(3) developing the exposed resist film using a developer containing an organic solvent to form a negative resist pattern;
(4) forming an inorganic layer so as to cover the resist pattern surface;
(5) Etching back the inorganic layer to remove a portion other than the portion formed on the sidewall of the resist pattern; and (6) Removing the resist pattern to form an inorganic pattern. ,
The photoresist composition is
[A] a polymer having a structural unit (I) containing an acid dissociable group and a structural unit (II) containing at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure, and [B] A method for forming a fine pattern containing an acid generator.

  According to the method for forming a fine pattern of the present invention, a resist pattern and an inorganic pattern having a low LWR and a good shape can be obtained by using the photoresist composition having the above steps and having the above composition as the photoresist composition. As a result, a good fine pattern can be formed on the substrate to be processed. Although the reason why the fine pattern forming method has the above-described configuration exerts the above-mentioned effect is not necessarily clear, for example, in the step (3), development is performed using a developer containing an organic solvent and used. By adopting a polymer having the structural unit (I) and the structural unit (II) as the polymer constituting the photoresist composition, the LWR is smaller and rectangular compared to the conventional method such as alkali development. A resist pattern having a high and good shape can be formed, and the polymer constituting the resist pattern to be formed has a polar group by using the above developing method, so that an inorganic pattern can be formed satisfactorily. Etc. are considered.

(7) It is preferable to further include a step of dry etching the substrate to be processed using the inorganic pattern as a mask.
According to the method for forming a fine pattern, by further including the above-described steps, it is possible to reliably form a good pattern on the substrate to be processed based on the good inorganic pattern having a small LWR formed.

The inorganic layer is preferably formed by a CVD method or an ALD method.
According to the method for forming a fine pattern, by forming the inorganic layer by the specific method, the LWR of the formed inorganic layer can be further reduced, and as a result, an even better pattern can be formed on the substrate to be processed. Can be formed.

  As described above, according to the fine pattern forming method of the present invention, a resist pattern and an inorganic pattern having a small LWR and a good shape can be formed, and a good pattern can be formed on the substrate to be processed.

It is a schematic process drawing which shows one Embodiment of the formation method of the fine pattern of this invention.

<Fine pattern formation method>
The fine pattern forming method of the present invention comprises:
(1) A step of applying a photoresist composition on a substrate to be processed to form a resist film,
(2) a step of exposing the resist film;
(3) developing the exposed resist film using a developer containing an organic solvent to form a negative resist pattern;
(4) forming an inorganic layer so as to cover the resist pattern surface;
(5) Etching back the inorganic layer to remove a portion other than the portion formed on the sidewall of the resist pattern; and (6) Removing the resist pattern to form an inorganic pattern. ,
The photoresist composition is
[A] a polymer having a structural unit (I) containing an acid dissociable group and a structural unit (II) containing at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure , “[A] polymer”), and [B] an acid generator.

Moreover, in addition to the said (1)-(6) process, the formation method of the said fine pattern,
(7) It is preferable to further include a step of dry etching the substrate to be processed using the inorganic pattern as a mask.
Hereinafter, each step of the fine pattern forming method and the photoresist composition used in the present invention will be described in order.

[(1) Process]
In this step, as shown in FIG. 1 (A), the photoresist composition is applied onto the substrate 1 to be processed, and a resist film 2 is formed.

  Examples of the substrate 1 to be processed include conventionally known substrates such as a silicon wafer and a wafer coated with aluminum.

  Note that an intermediate layer may be first formed on the substrate 1 to be processed, and the resist film 2 may be formed on the intermediate layer. Examples of the intermediate layer include a thin film such as a conductive polysilicon film, an organic or inorganic lower antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, and the like. Is mentioned. Two or more layers may be formed as the intermediate layer.

  Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. In addition, as a film thickness of the resist film formed, it is 10 nm-1,000 nm normally, and 10 nm-500 nm are preferable.

  After apply | coating the said photoresist composition, you may volatilize the solvent in a coating film by prebaking (PB) as needed. The PB temperature is appropriately selected depending on the composition of the photoresist composition, but is usually 30 ° C to 200 ° C, preferably 50 ° C to 150 ° C. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

  On the resist film 2, for example, a protective film disclosed in Japanese Patent Application Laid-Open No. 5-188598 may be provided in order to prevent the influence of basic impurities contained in the environmental atmosphere. In order to prevent the acid generator and the like from flowing out of the resist film during immersion exposure, for example, an immersion protective film disclosed in JP-A-2005-352384 may be provided. These techniques can be used in combination.

[(2) Process]
In this step, as shown in FIG. 1A, the resist film 2 formed in the step (1) is irradiated with exposure light a to perform exposure. This exposure is performed by performing reduction projection or the like on a desired area through a mask having a specific pattern and, if necessary, an immersion liquid. For example, an isospace pattern can be formed by performing exposure through a mask having an isoline pattern in a desired region. Similarly, a hole pattern can be formed by performing exposure through a mask having a dot pattern. Moreover, you may perform exposure twice or more with a desired mask pattern. When performing exposure twice or more, it is preferable to perform exposure continuously. In the case of performing multiple exposures, for example, the first exposure is performed on a desired region through a line and space pattern mask, and then the second exposure is performed so that the line intersects the exposure unit that has performed the first exposure. I do. The first exposure part and the second exposure part are preferably orthogonal. By being orthogonal, a contact hole pattern can be formed in the unexposed area surrounded by the exposed area.

  Examples of the immersion liquid include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient as small as possible so as to minimize distortion of the optical image projected onto the resist film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), water is preferable from the viewpoints of availability and handling in addition to the above viewpoints.

  The exposure light is appropriately selected according to the type of the [B] acid generator. For example, electromagnetic waves such as ultraviolet rays, far ultraviolet rays, X-rays and γ rays; charged particle beams such as electron rays and α rays, etc. Is mentioned. Among these, far ultraviolet rays are preferable, ArF excimer laser light and KrF excimer laser light (wavelength 248 nm) are more preferable, and ArF excimer laser light is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the composition of the photoresist composition and the type of additive. In the fine pattern forming method, the exposure may be performed a plurality of times as described above, and the same light source or different light sources may be used in the plurality of exposures. However, it is preferable to use ArF excimer laser light for the first exposure.

  Post-exposure baking (PEB) is preferably performed after the exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the photoresist composition can proceed smoothly, and the shape of the resist pattern to be formed can be made better. The shape of the pattern formed on the substrate can be made better. As PEB temperature, it is 30 to 200 degreeC normally, and 50 to 170 degreeC is preferable. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[(3) Process]
In this step, the resist film 2 exposed in the step (2) is developed using a developer containing an organic solvent to form a negative resist pattern 2 ′ as shown in FIG. The resist pattern 2 ′ includes a plurality of walls and a space between the walls. The developer used in this step is a negative developer containing an organic solvent. This negative developer preferably further contains a nitrogen-containing compound. When the developer further contains a nitrogen-containing compound in addition to the organic solvent, the developer insolubility of the exposed portion of the resist film is improved, and film loss can be suppressed. Here, the negative developer is a developer that selectively dissolves and removes the low-exposed portion and the unexposed portion. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass. By making the content of the organic solvent in the developer within the above range, the dissolution contrast between the exposed and unexposed areas can be improved, so that a resist pattern with excellent lithography characteristics can be formed. As a result, the shape of the pattern formed on the substrate to be processed can be made better. Examples of components other than the organic solvent include water and silicon oil.

  Examples of the organic solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester organic solvents, hydrocarbon solvents, and the like.

As an alcohol solvent, for example,
Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furf Alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, mono-alcohol solvents such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

As an ether solvent, for example,
Dialiphatic ether solvents such as diethyl ether, dipropyl ether, dibutyl ether;
Aromatic ring ether solvents such as anisole and diphenyl ether;
Examples thereof include cyclic ether solvents such as tetrahydrofuran and dioxane.

Examples of ketone solvents include:
Acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-amyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone Chain ketone solvents such as trimethylnonanone and acetophenone;
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
And diketone solvents such as 2,4-pentanedione and acetonylacetone.

Examples of the amide solvent include
Chain amide solvents such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide;
Examples thereof include cyclic amide solvents such as N-methylpyrrolidone and N, N′-dimethylimidazolidinone.

Examples of ester solvents include:
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n propionate -Butyl, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate, etc. Carboxylate solvent;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl acetate Carboxylic acid ester solvents of polyhydric alcohol partial ethers such as ether, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Lactone solvents such as γ-butyrolactone and γ-valerolactone;
Examples thereof include carbonate solvents such as diethyl carbonate and propylene carbonate.

Examples of the hydrocarbon solvent include
Aliphatic carbonization such as n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, methylcyclohexane A hydrogen-based solvent;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents and the like.

  Among these, from the viewpoint of improving the LWR and shape of the resist pattern and inorganic pattern formed in the fine pattern forming method, ester solvents, ketone solvents, and ether solvents are preferable, and ester solvents, ketones More preferred are carboxylic acid ester solvents and chain ketone solvents, n-butyl acetate, isopropyl acetate, amyl acetate, methyl ethyl ketone, methyl n-butyl ketone and methyl n-amyl ketone are particularly preferred, and acetic acid is preferred. Particularly preferred are n-butyl and methyl n-amyl ketone, and most preferred is n-butyl acetate. These organic solvents can be used individually by 1 type or in combination of 2 or more types.

  The nitrogen-containing compound interacts with a polar group such as a carboxy group generated in the structural unit (I) of the [A] polymer in the resist film by the action of an acid generated from the [B] acid generator, The insolubility of the exposed part with respect to can be further improved. Here, the interaction between the nitrogen-containing compound and the polar group includes an action of reacting the nitrogen-containing compound and the polar group to form a salt, an action of forming an ionic bond, and the like.

  The nitrogen-containing compound is preferably a compound represented by the following formula (A).

In the above formula (A), R ^a and R ^b are each independently a hydrogen atom, a hydroxy group, a formyl group, an alkoxy group, an alkoxycarbonyl group, a chain hydrocarbon group having 1 to 30 carbon atoms, or a carbon number of 3 It is a group formed by combining 2 or more types of -30 alicyclic hydrocarbon groups, C6-C14 aromatic hydrocarbon groups, or these groups. R ^c is an m-valent chain hydrocarbon group having 1 to 30 carbon atoms, an m-valent alicyclic hydrocarbon group having 3 to 30 carbon atoms, an m-valent aromatic hydrocarbon group having 6 to 14 carbon atoms, or It is an m-valent group formed by combining two or more of these groups. m is an integer of 1 or more. However, when m is 2 or more, the plurality of R ^a and R ^b may be the same or different. When m is 1, R ^c may be a hydrogen atom, a hydroxy group, a formyl group, an alkoxy group, or an alkoxycarbonyl group. Some or all of the hydrogen atoms of R ^{a to} R ^c may be substituted. Further, any two of R ^{a to} R ^c may be bonded to form a ring structure together with the nitrogen atom to which they are bonded.

Examples of the C1-C30 chain hydrocarbon group represented by R ^a and R ^b include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and 2-methyl. A propyl group, a 1-methylpropyl group, a t-butyl group, etc. are mentioned.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atoms represented by R ^a and R ^b include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, and a norbornyl group.

As ^a C6-C14 aromatic hydrocarbon group represented by said R <a> and R < ^b >, a phenyl group, a tolyl group, a naphthyl group etc. are mentioned, for example.

Examples of the group formed by combining two or more of these groups represented by R ^a and R ^b include aralkyl groups having 6 to 12 carbon atoms such as benzyl group, phenethyl group, naphthylmethyl group, naphthylethyl group, and the like. Is mentioned.

Examples of the m-valent chain hydrocarbon group having 1 to 30 carbon atoms represented by R ^c are exemplified as the chain hydrocarbon group having 1 to 30 carbon atoms represented by the above R ^a and R ^b . And a group obtained by removing (m−1) hydrogen atoms from the same group as the group.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atoms represented by R ^c include the groups exemplified as the alicyclic hydrocarbon group having 3 to 30 carbon atoms represented by the above R ^a and R ^b. Examples include a group obtained by removing (m-1) hydrogen atoms from the same group.

The m-valent aromatic hydrocarbon group having 6 to 14 carbon atoms represented by R ^c is exemplified as the aromatic hydrocarbon group having 6 to 14 carbon atoms represented by R ^a and R ^b , for example. And a group obtained by removing (m−1) hydrogen atoms from the same group as the group.

Examples of the m-valent group formed by combining two or more of these groups represented by R ^c include, for example, groups exemplified as a group formed by combining two or more of these groups represented by R ^a and R ^b. And a group obtained by removing (m-1) hydrogen atoms from the same group.

The groups represented by R ^{a to} R ^c may be substituted. Specific examples of the substituent include a methyl group, an ethyl group, a provir group, an n-butyl group, a t-butyl group, a hydroxy group, a carboxy group, a halogen atom, and an alkoxy group. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Moreover, as an alkoxy group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group etc. are mentioned, for example.

  Examples of the compound represented by the above formula (A) include (cyclo) alkylamine compounds, nitrogen-containing heterocyclic compounds, amide group-containing compounds, urea compounds and the like.

  Examples of (cyclo) alkylamine compounds include compounds having one nitrogen atom, compounds having two nitrogen atoms, compounds having three or more nitrogen atoms, and the like.

Examples of the (cyclo) alkylamine compound having one nitrogen atom include mono (cyclo) alkyl such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, 1-aminodecane and cyclohexylamine. Amines;
Di-n-butylamine, di-n-pentylamine, di-n-hexylamine, di-n-heptylamine, di-n-octylamine, di-n-nonylamine, di-n-decylamine, cyclohexylmethylamine, Di (cyclo) alkylamines such as dicyclohexylamine;
Triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri -Tri (cyclo) alkylamines such as n-decylamine, cyclohexyldimethylamine, methyldicyclohexylamine, tricyclohexylamine;
Substituted alkylamines such as triethanolamine;
Aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, N, N-dibutylaniline, 4-nitroaniline, diphenylamine, triphenylamine, naphthylamine, 2 , 4,6-tri-tert-butyl-N-methylaniline, N-phenyldiethanolamine, 2,6-diisopropylaniline, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- ( And aromatic amines such as 4-aminophenyl) -2- (4-hydroxyphenyl) propane.

  Examples of the (cyclo) alkylamine compound having two nitrogen atoms include ethylenediamine, tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4, 4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 1,4- Bis [1- (4-aminophenyl) -1-methylethyl] benzene, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzene, bis (2-dimethylaminoethyl) ether, Bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) ) -2-imidazolidinone, 2-quinoxalinium linoleic, N, N, N ', N'-tetrakis (2-hydroxypropyl) ethylenediamine, and the like.

  Examples of the (cyclo) alkylamine compound having 3 or more nitrogen atoms include polymers such as polyethyleneimine, polyallylamine, and 2-dimethylaminoethylacrylamide.

  Examples of the nitrogen-containing heterocyclic compound include nitrogen-containing aromatic heterocyclic compounds and nitrogen-containing aliphatic heterocyclic compounds.

Examples of the nitrogen-containing aromatic heterocyclic compound include:
Imidazoles such as imidazole, 4-methylimidazole, 4-methyl-2-phenylimidazole, benzimidazole, 2-phenylbenzimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-methyl-1H-imidazole;
Pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, 2-methyl-4-phenylpyridine, nicotine, nicotinic acid, nicotinamide, Examples include quinoline, 4-hydroxyquinoline, 8-oxyquinoline, acridine, and pyridines such as 2,2 ′: 6 ′, 2 ″ -terpyridine.

Examples of the nitrogen-containing aliphatic heterocyclic compound include:
Piperazines such as piperazine and 1- (2-hydroxyethyl) piperazine;
Pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, proline, piperidine, piperidine ethanol, 3-piperidino-1,2-propanediol, morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine , 3- (N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane, and the like.

Examples of the amide group-containing compound include:
Nt-butoxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt-butoxycarbonyldicyclohexylamine, Nt- Butoxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, (S)-(−)-1- (t-butoxy Carbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonylpyrrolidine, Nt-butoxycarbonylpiperazine, N, N-di-t-butoxy Rubonyl-1-adamantylamine, N, N-di-t-butoxycarbonyl-N-methyl-1-adamantylamine, Nt-butoxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t -Butoxycarbonylhexamethylenediamine, N, N, N ', N'-tetra-t-butoxycarbonylhexamethylenediamine, N, N'-di-t-butoxycarbonyl-1,7-diaminoheptane, N, N' -Di-t-butoxycarbonyl-1,8-diaminooctane, N, N'-di-t-butoxycarbonyl-1,9-diaminononane, N, N'-di-t-butoxycarbonyl-1,10-diamino Decane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N′-di-t-butoxycarbonyl-4,4′-diamino Nt-butoxycarbonyl group-containing amino compounds such as diphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole;
Formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, isocyanuric Examples include acid tris (2-hydroxyethyl).

  Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tri-n-butylthiourea. Etc.

  Among these, (cyclo) alkylamine compounds and nitrogen-containing aliphatic heterocyclic compounds are preferable, and 1-aminodecane, di-n-octylamine, tri-n-octylamine, tetramethylethylenediamine, N, N-dibutylaniline. Proline is more preferable.

  An appropriate amount of a surfactant can be added to the developer as necessary. Examples of the surfactant include ionic and nonionic fluorine-based and / or silicon-based surfactants.

  As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

  (3) It is preferable to include a rinsing step of washing the formed resist pattern 2 'with a rinsing liquid after the step. As the rinsing liquid in the rinsing step, for example, an organic solvent can be used. By using an organic solvent as the rinsing liquid, the generated scum can be efficiently washed.

  Examples of the organic solvent used as the rinsing liquid include hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and the like. Among these, alcohol solvents and ester solvents are preferable, alcohol solvents are more preferable, and monovalent alcohol solvents having 6 to 8 carbon atoms are more preferable.

  Examples of the monovalent alcohol solvent having 6 to 8 carbon atoms include linear, branched or cyclic monovalent alcohols, and specifically, 1-hexanol, 1-heptanol, 1- Examples include octanol, 4-methyl-2-pentanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, and benzyl alcohol. Among these, 1-hexanol, 2-hexanol, 2-heptanol, and 4-methyl-2-pentanol are preferable, and 4-methyl-2-pentanol is more preferable.

  Each component of the rinse liquid may be used alone or in combination of two or more. The water content in the rinse liquid is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less. By setting the water content in the rinse liquid to 10% by mass or less, good development characteristics can be obtained. A surfactant may be added to the rinse liquid.

  Examples of the cleaning treatment using the rinsing liquid include, for example, a method of continuously applying the rinsing liquid onto a substrate rotating at a constant speed (rotary coating method), and immersing the substrate in a tank filled with the rinsing liquid for a predetermined time. Examples thereof include a method (dip method) and a method (spray method) of spraying a rinsing liquid on the substrate surface.

[(4) Process]
In this step, as shown in FIG. 1C, the inorganic layer 3 is formed so as to cover the surface of the resist pattern 2 ′ formed in the step (3). Specifically, the inorganic layer 3 is formed on the upper surface of the substrate to be processed in the upper and side surfaces of the walls constituting the resist pattern 2 ′ and the space portion between the walls by this step.

  Examples of the material constituting the inorganic layer 3 include silicon-containing materials such as silicon oxide, silicon nitride, silicon nitride oxide, and polysilicon; metal-containing materials such as aluminum oxide, titanium nitride, titanium boride, tungsten, and hafnium oxide. Is mentioned. Among these, silicon oxide is preferable from the viewpoint that it can be formed at a lower temperature.

  The inorganic layer 3 is formed by a known method such as CVD (Chemical Vapor Deposition), ALD (Atomic Layer Deposition), PVD (Physical Vapor Deposition), or the like. Various methods can be used.

Examples of the CVD method include various methods such as thermal CVD, plasma CVD, photo CVD, reduced pressure CVD, and laser CVD metal organic CVD (MOCVD).
Examples of the PVD method include vacuum vapor deposition, electron beam vapor deposition, reactive vapor deposition, glow discharge sputtering, ion beam sputtering, reactive sputtering, ion plating, and a cluster ion beam method.
Examples of the ALD method include a thermal ALD method and a plasma ALD method.

  Of these, the CVD method and the ALD method are preferable. By forming the inorganic layer using a CVD method or an ALD method, the LWR of the formed inorganic pattern can be further reduced, and as a result, the shape of the pattern to be formed can be further improved. Among these, plasma CVD and plasma ALD are preferable from the viewpoint of obtaining a high-quality inorganic layer.

  In plasma CVD and plasma ALD, for example, as a source gas when forming an inorganic layer containing silicon oxide, for example, silane-based gases such as silane, chlorosilane, alkoxysilane, and isocyanatesilane are used.

  The thickness of the inorganic layer 3 to be formed is not particularly limited as long as it is not more than half the space width of the resist pattern 2 ′, but is usually 1 nm to 500 nm, preferably 5 nm to 200 nm, more preferably 10 nm to 100 nm. 10 nm-50 nm are more preferable.

[(5) Process]
In this step, as shown in FIG. 1D, the inorganic layer 3 formed in the step (4) is etched back, and portions other than the portion 3 ′ formed on the sidewall of the resist pattern are removed. Specifically, the space portion between the upper surface of the resist pattern 2 ′ and the resist pattern 2 ′ in the inorganic layer 3 is removed by removing a certain height of the formed inorganic layer 3 by this step. The portion formed on the side of the resist pattern 2 ′ disappears, and the portion formed on the side wall of the resist pattern 2 ′ remains.

As the method for performing the etch back, various known methods can be used, and examples thereof include anisotropic etching such as reactive ion etching (RIE). As an etching gas used in RIE in this step, for example, a fluorine-based gas such as CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ , NF ₃ ; Cl ₂ , BCl ₃ , SiCl ₄ , Examples include chlorine-based gases such as CCl ₄ ; mixed gases of these gases such as HBr and O ₂ and inert gases such as N ₂ , He, and Ar. Among these, a fluorine-based gas or a mixed gas of a fluorine-based gas and an inert gas is preferable.

[(6) Step]
In this step, as shown in FIG. 1E, the resist pattern is removed to form an inorganic pattern 3 ″. Various known methods are used as a method of removing the resist pattern used in this step. However, anisotropic etching such as the RIE method can be used, etc. Examples of the etching gas used in the RIE method in this step include oxygen-based gases such as O ₂ , O ₃ , and H ₂ O, Examples thereof include a mixed gas of these gases and an inert gas such as N ₂ , He, or Ar.

[(7) Process]
In this step, the processed substrate 1 is dry-etched using the inorganic pattern 3 ″ formed in the step (6) as a mask. As a result, a processed substrate 1 ′ having a pattern is obtained. Used in this step. Various known methods can be used as the dry etching method, but the RIE method is preferable.

<Photoresist composition>
The photoresist composition used in the present invention contains a [A] polymer and a [B] acid generator. Moreover, the said photoresist composition may contain a [C] fluorine atom containing polymer, a [D] acid diffusion control body, a [E] solvent, and another component, unless the effect of this invention is impaired. . Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer has a structural unit (I) containing an acid dissociable group and a structural unit (II) containing at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure. . [A] The polymer may have other structural units such as the structural unit (III) containing a polar group in addition to the structural unit (I) and the structural unit (II). In addition, the [A] polymer may have each structural unit individually by 1 type or 2 types or more. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit containing an acid dissociable group. The “acid-dissociable group” refers to a group that substitutes a hydrogen atom of a polar group such as a carboxy group or a hydroxy group, and dissociates by the action of an acid. [A] The polymer has the structural unit (I), so that [B] the acid dissociable group is dissociated by the action of an acid generated from the acid generator and the solubility in a developer containing an organic solvent is obtained. Decrease. As a result, in the fine pattern forming method, according to the photoresist composition containing the [A] polymer, a negative resist pattern can be formed.

  Examples of the structural unit (I) include a structural unit represented by the following formula (1).

In said formula (1), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ² is a monovalent acid dissociable group.

Examples of the monovalent acid dissociable group represented by R ² include a group represented by the following formula (i).

In said formula (i), R ^<p1> , R ^<p2> and R ^<p3> are respectively independently a C1-C4 alkyl group or a C4-C20 monovalent alicyclic hydrocarbon group. However, R ^p2 and R ^p3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^{p1 to} R ^p3 include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, Examples include 1-methylpropyl group and t-butyl group.

Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by the above R ^{p1 to} R ^p3 include a monocyclic alicyclic hydrocarbon group having a cycloalkane skeleton such as cyclopentane and cyclohexane;
And polycyclic alicyclic hydrocarbon groups having a bridged skeleton such as an adamantane skeleton and a norbornane skeleton.

Among these, R ^p1 is an alkyl group having 1 to 4 carbon atoms, R ^p2 and R ^p3 are bonded to each other, and a divalent group having an adamantane skeleton or a cycloalkane skeleton together with the carbon atom to which they are bonded Is preferably formed.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-4) (hereinafter also referred to as “structural units (I-1) to (I-4)”). Etc.

In the above formulas (1-1) to (1-4), R ¹ has the same meaning as the above formula (1). R ^p1 , R ^p2 and R ^p3 are as defined in the above formula (i). n _p is an integer of 1 to 4.

As _np , 1 or 2 is preferable and 1 is more preferable.

  Examples of the structural unit (I) include a structural unit represented by the following formula.

In the above formula, ^{R 1} is as defined in the above formula (1).

  As the structural unit (I), from the viewpoint that the LWR of the resist pattern and the inorganic pattern formed in the fine pattern forming method can be reduced and the shape can be improved, the structural units (I-1), (I -2) and (I-3) are preferred, structural units (I-2) and (I-3) are more preferred, and 1-methyl-1-cyclopentyl (meth) acrylate, 1-ethyl-1-cyclopentyl (meta) ) And structural units derived from 2- (1-adamantyl) propyl (meth) acrylate are more preferred.

  As a content rate of structural unit (I), it is preferable that it is 20 mol%-80 mol%, and it is more preferable that it is 30 mol%-70 mol%. By setting the content ratio of the structural unit (I) in the above range, the LWR of the resist pattern and the inorganic pattern formed in the fine pattern forming method can be further reduced, and the shape can be improved. it can.

[Structural unit (II)]
The structural unit (II) is a structural unit including at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. [A] Since the polymer has the structural unit (II), the LWR of the formed resist pattern can be reduced and the shape can be improved in the fine pattern forming method. In addition, the adhesion of the resist pattern to the substrate can be improved. Here, the lactone structure refers to a structure having one ring (lactone ring) including a group represented by —O—C (O) —. The cyclic carbonate structure refers to a structure having one ring (cyclic carbonate ring) including a group represented by —O—C (O) —O—. The sultone structure refers to a structure having one ring (sultone ring) including a group represented by —O—S (O) ₂ —. When the lactone ring, cyclic carbonate ring or sultone ring is counted as the first ring, and the ring structure included in the structure is only a lactone ring, cyclic carbonate ring or sultone ring, it is monocyclic, and when it has another ring structure Regardless of its structure, it is called polycyclic.

  Examples of the structural unit (II) include a structural unit represented by the following formula (2).

In the above formula (2), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁴ is a single bond or a divalent linking group. R ⁵ is a monovalent group containing a lactone structure, a monovalent group containing a cyclic carbonate structure, or a monovalent group containing a sultone structure.

Examples of the divalent linking group represented by R ⁴ include, for example, a divalent linear or branched hydrocarbon group having 1 to 20 carbon atoms, one or more of these hydrocarbon groups, and —CO—, And groups composed of at least one group selected from the group consisting of —O—, —NH—, and —S—.

Examples of the monovalent group containing a lactone structure represented by R ⁵ , the monovalent group containing a cyclic carbonate structure, and the monovalent group containing a sultone structure include the following formulas (R5-1) to (R5- 11) etc. are mentioned.

In the above formulas (R5-1) to (R5-4), R ^L1 is an oxygen atom or a methylene group. R ^L2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n _L1 is 0 or 1. n _L2 is an integer of 0 to 3.
The formula (R5-7) and (R5-8) _{in, n C1} represents an integer of 0 to 2. n _{C2 to} n _C5 are each independently an integer of 0 to 2.
In the above formulas (R5-9) to (R5-11), R ^S1 represents an oxygen atom or a methylene group. R ^S2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n _S1 is 0 or 1. n _S2 is an integer of 0 to 3.
In the above formula (R5-1) ~ (R5-11), * represents a site that binds to ^{R 4} in the formula (2).
Part or all of the hydrogen atoms of the groups represented by the above formulas (R5-1) to (R5-11) may be substituted.

Among these, R ⁵ is preferably a group represented by (R5-1), (R5-3), (R5-7) and (R5-9), and (R5-1) and (R5- The group represented by 7) is more preferable.
As said R ^<L1> and R ^<S1> , a methylene group is preferable. As R ^L2 and R ^S2 , a hydrogen atom is preferable. As said _nL1 and _nS1 , 0 is preferable. As said _nL2 and _nS2 , 1 or 2 is preferable and 1 is more preferable.
The group that replaces the hydrogen atom of the norbornane ring of the groups represented by (R5-1) and (R5-7) is preferably a cyano group, a trifluoromethyl group, or a methoxycarbonyl group, and more preferably a cyano group. .

  Examples of the structural unit (II) include a structural unit represented by the following formula.

In the above formula, R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

Among these, as structural unit (II),
The structural unit containing a lactone structure is preferably a structural unit having a norbornane lactone group, a structural unit having a cyano group-substituted norbornane lactone group, or a structural unit having a butyrolactone group, and more preferably a structural unit having a norbornane lactone group.
As the structural unit containing a cyclic carbonate structure, a structural unit containing an ethylene carbonate group is preferred.
As a structural unit containing a sultone structure, a structural unit having a norbornane sultone group is preferable.

  As a monomer which gives structural unit (II), the monomer etc. which are represented by following formula (2-m) are mentioned, for example.

In the formula (2-m), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁴ is a single bond or a divalent linking group. R ⁵ is a monovalent group containing a lactone structure, a monovalent group containing a cyclic carbonate, or a monovalent group containing a sultone structure.

Examples of R ⁴ and R ⁵ include groups similar to those exemplified as the groups represented by R ⁴ and R ⁵ in Formula (2).

  As a content rate of structural unit (II), 20 mol%-80 mol% are preferable, 30 mol%-70 mol% are more preferable, and 35 mol%-65 mol% are more preferable. By making the content rate of structural unit (II) into the said range, the LWR and shape of the resist pattern and inorganic pattern which are formed in the formation method of the said fine pattern can be improved. Moreover, the adhesiveness of the resist pattern formed can be improved.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a polar group. [A] Since the polymer further has the structural unit (III), the polarity of the [A] polymer can be adjusted to adjust the solubility of the [A] polymer in the developer during development, As a result, the resist pattern shape and the like in the fine pattern forming method can be improved.

  Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a keto group (═O), a nitro group, and a sulfonamide group. Among these, a hydroxy group, a carboxy group, and a keto group are preferable, and a hydroxy group and a keto group are more preferable.

  Examples of the structural unit (III) include a structural unit represented by the following formula.

In the above formula, R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  Among these, a structural unit having an adamantane skeleton is preferable, and a structural unit derived from 3-hydroxy-1-adamantyl (meth) acrylate and a structural unit derived from 4-oxo-1-adamantyl (meth) acrylate are preferable.

  As a content rate of structural unit (III), 30 mol% or less is preferable, 20 mol% or less is more preferable, and 15 mol% or less is further more preferable.

  [A] The polymer may have other structural units such as a structural unit containing a non-acid dissociable alicyclic hydrocarbon group in addition to the structural units (I) to (III). Good. As a content rate of another structural unit, 20 mol% or less is preferable and 10 mol% or less is more preferable.

  As content of the [A] polymer in the said photoresist composition, 70 mass% or more is preferable with respect to the total solid, 80 mass% or more is more preferable, 85 mass% or more is further more preferable.

<[A] Polymer Synthesis Method>
[A] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator. For example, a method of dropping a solution containing a monomer and a radical initiator into a reaction solvent or a solution containing the monomer to cause a polymerization reaction, a solution containing the monomer, and a solution containing the radical initiator Separately, a method of dropping a reaction solvent or a monomer-containing solution into a polymerization reaction, a plurality of types of solutions containing each monomer, and a solution containing a radical initiator, It is preferable to synthesize by a method such as a method of dropping it into a reaction solvent or a solution containing a monomer to cause a polymerization reaction.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These solvents may be used alone or in combination of two or more.

  Although the reaction temperature in the said polymerization should just be suitably determined according to the kind of radical initiator, it is 40 to 150 degreeC normally, and 50 to 120 degreeC is preferable. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2 -Cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionitrile) and the like. These radical initiators may be used alone or in combination of two or more.

  The polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols, alkanes and the like can be used singly or in combination of two or more. In addition to the reprecipitation method, the polymer can be recovered by removing low-molecular components such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

  [A] As a weight average molecular weight (Mw) by the gel permeation chromatography (GPC) of a polymer, 1,000-100,000 are preferable, 1,000-50,000 are more preferable, 1,000-30 1,000 is more preferable, and 1,000 to 10,000 is particularly preferable. [A] By making Mw of a polymer into the said range, LWR and pattern shape of the resist pattern formed in the formation method of the said fine pattern can be improved.

  [A] The ratio (Mw / Mn) of Mw and number average molecular weight (Mn) of the polymer is usually 1 to 5, preferably 1 to 3, and more preferably 1 to 2. By setting Mw / Mn within the above range, the LWR and pattern shape of the resist pattern formed in the fine pattern forming method can be improved.

  In this specification, Mw and Mn are GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL, manufactured by Tosoh), flow rate 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1. A value measured by GPC using a monodisperse polystyrene as a standard using a differential refractometer as a detector under the analysis conditions of 0% by mass, sample injection amount: 100 μL, column temperature: 40 ° C.

<[B] Acid generator>
[B] The acid generator is a compound that generates an acid upon exposure to exposure light in the step (2) in the fine pattern forming method. Due to the action of the acid, the acid-dissociable group present in the [A] polymer is dissociated to produce a polar group such as a carboxy group. As a result, the [A] polymer contains the organic solvent in the step (3). It becomes hardly soluble in the developing solution. [B] The acid generator may be contained in the form of a compound as described later (hereinafter also referred to as “[B] acid generator” as appropriate), or in a form incorporated as part of a polymer. Both forms are acceptable.

  [B] Examples of the acid generator include onium salt compounds, N-sulfonylimide compounds, halogen-containing compounds, diazoketone compounds, and the like.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  Examples of the sulfonium salt 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 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexyl Ruphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexyl Phenyldiphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methane Sulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetraph Oroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, triphenylsulfonium 6- (1-adamantylcarbonyloxy) -1,1,2,2-tetrafluorohexane-1-sulfonate, triphenylsulfonium norbornyl- Examples include difluoroethane sulfonate.

  Examples of the tetrahydrothiophenium salt 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) tetrahydrothio Phenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphor Sulfonate, 1- (6-n-butoxynaphthalen-2-yl) Tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothio Phenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2, 2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl- -Hydroxyphenyl) tetrahydrothiophenium 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, 1- (3,5-dimethyl-4- Hydroxyphenyl) tetrahydrothiophenium camphorsulfonate and the like.

  Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl. -1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate Bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2. .1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like.

  Of these, onium salts are preferable, sulfonium salts are more preferable, triphenylsulfonium 6- (1-adamantylcarbonyloxy) -1,1,2,2-tetrafluorohexane-1-sulfonate, triphenylsulfonium 2- Bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate and 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate are more preferable.

  [B] The acid generator may be used alone or in combination of two or more. [B] The content when the acid generator is a [B] acid generator is as follows. From the viewpoint of ensuring the sensitivity and developability of the above photoresist composition as a resist, On the other hand, 0.1 to 30 parts by mass is preferable, 0.5 to 20 parts by mass is more preferable, and 1 to 15 parts by mass is further preferable. [B] If the content of the acid generator is less than 0.1 parts by mass, the sensitivity tends to be insufficient. On the other hand, if it exceeds 30 parts by mass, the transparency to the exposure light decreases, and a desired resist pattern is formed. It may be difficult to obtain.

<[C] Fluorine atom-containing polymer>
The photoresist composition preferably contains a [C] fluorine atom-containing polymer. The photoresist composition contains a [C] fluorine atom-containing polymer, and when the resist film is formed, the distribution of the resist film surface layer depends on the oil-repellent characteristics of the [C] fluorine atom-containing polymer. Therefore, at the time of immersion exposure, elution to the immersion medium such as the [B] acid generator in the resist film and the [D] acid diffusion controller described later can be suppressed. In addition, as a [C] fluorine atom containing polymer, the polymer applicable to a [A] polymer shall be remove | excluded.

  [C] The fluorine atom-containing polymer can be usually formed by polymerizing one or more monomers containing fluorine atoms in the structure.

  [C] The fluorine atom-containing polymer preferably has the following structural unit (FI) as a structural unit containing a fluorine atom in the structure. Moreover, the [C] fluorine atom containing polymer may have other structural units other than the structural unit which contains a fluorine atom in a structure. [C] The fluorine atom-containing compound may have one or more of these structural units.

[Structural unit (FI)]
The structural unit (FI) is a structural unit represented by the following formula (C1).

In the formula (C1), R ⁷ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a single bond or a divalent linking group. R ⁸ is a C 1-6 alkyl group having at least one fluorine atom, a C 4-20 monovalent alicyclic hydrocarbon group, or a derivative thereof.

  Examples of the divalent linking group represented by A include an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylimide group, and a urethane group.

  Preferred monomers that give the structural unit (FI) include trifluoromethyl (meth) acrylic acid ester, 2,2,2-trifluoroethyl (meth) acrylic acid ester, and perfluoroethyl (meth) acrylic. Acid ester, perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n-butyl (meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester , Perfluoro t-butyl (meth) acrylate, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylate, 1- (2,2,3,3, 4,4,5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) ) Acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7, 7,8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6 , 6-octafluorohexyl) (meth) acrylic acid ester.

  As a content rate of a structural unit (FI), 5 mol% or more is preferable with respect to all the structural units which comprise a [C] fluorine atom containing polymer, 10 mol% or more is more preferable, 15 mol% or more Is more preferable. If the content of the structural unit (FI) is less than 5 mol%, the receding contact angle may be less than 70 degrees, and elution of the acid generator from the resist film cannot be suppressed. May occur. [C] The fluorine atom-containing polymer may have only one type of structural unit (FI), or may have two or more types.

[Other structural units]
[C] The fluorine atom-containing polymer has a structure having an acid-dissociable group in order to control, for example, the dissolution rate in a developer, in addition to the above-described structural unit containing a fluorine atom in the structure. A structural unit containing at least one structure selected from the group consisting of a unit, a lactone structure, a cyclic carbonate structure and a sultone structure, a structural unit containing a polar group such as a hydroxyl group and a carboxy group, a structural unit containing an alicyclic group, and a substrate In order to suppress light scattering due to reflection from the light, one or more structural units derived from an aromatic compound can be contained.

Examples of the structural unit having an acid dissociable group include structural units similar to the structural unit (I) of the polymer [A].
Examples of the structural unit containing at least one structure selected from the group consisting of the lactone structure, the cyclic carbonate structure, and the sultone structure include the same structural units as the structural unit (II) of the polymer [A]. .
Examples of the structural unit containing the polar group include structural units similar to the structural unit (III) of the [A] polymer.

  Examples of the structural unit containing the alicyclic group include a structural unit represented by the following formula (C2).

In said formula (C2), R < ⁹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X is a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by X include cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, and bicyclo [2.2.2. ] Octane, tricyclo [5.2.1.0 ^2,6 ] decane, tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing one hydrogen atom from an alicyclic hydrocarbon such as 0 ^2,7 ] dodecane and tricyclo [3.3.1.1 ^3,7 ] decane. Some or all of the hydrogen atoms possessed by the monovalent alicyclic hydrocarbon group are methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1- A linear or branched alkyl group having 1 to 4 carbon atoms, such as a methylpropyl group or a t-butyl group, a cycloalkyl group having 3 to 10 carbon atoms; a hydroxy group, a cyano group, or a hydroxyalkyl having 1 to 10 carbon atoms Group and a carboxy group may be substituted. Further, two hydrogen atoms bonded to the same carbon atom may be substituted with one oxygen atom to form a keto group.

Preferred monomers that give structural units containing the alicyclic group include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-bicyclo [2.2. .2] Oct-2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.02,6] dec-7-yl ester, (meth) acrylic acid-tetracyclo [6.2.1.13. , 6.0 ^2,7 ] dodeca-9-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-1-yl ester, (meth) acrylic acid-tricyclo [3 .3.1.1 ^3,7 ] dec-2-yl ester.

  Preferred monomers that give structural units derived from the aromatic compound include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, 4- (2-t-butoxycarbonylethyloxy) styrene 2-hydroxystyrene, 3-hydroxystyrene, 4-hydroxystyrene, 2-hydroxy-α-methylstyrene, 3-hydroxy-α-methylstyrene 4-hydroxy-α-methylstyrene, 2-methyl-3-hydroxystyrene, 4-methyl-3-hydroxystyrene, 5-methyl-3-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl- 4-hydroxystyrene, 3,4-dihydroxystyrene, 2 4,6-trihydroxystyrene, 4-t-butoxystyrene, 4-t-butoxy-α-methylstyrene, 4- (2-ethyl-2-propoxy) styrene, 4- (2-ethyl-2-propoxy) -Α-methylstyrene, 4- (1-ethoxyethoxy) styrene, 4- (1-ethoxyethoxy) -α-methylstyrene, phenyl (meth) acrylate, benzyl (meth) acrylate, acenaphthylene, 5-hydroxyacena Butylene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-hydroxy-6-vinylnaphthalene, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, 1-naphthylmethyl (meth) acrylate, 1-anthryl (Meth) acrylate, 2-anthryl (meth) acrylate, 9-anthryl (meta ) Acrylate, 9-anthrylmethyl (meth) acrylate, 1-vinylpyrene.

  As a content rate of said other structural unit, it is 80 mol% or less normally, 75 mol% or less is preferable and 70 mol% or less is more preferable.

  [C] The content of the fluorine atom-containing polymer is preferably 0.1 part by mass to 30 parts by mass, and more preferably 0.5 part by mass to 20 parts by mass with respect to 100 parts by mass of the polymer [A]. 1 mass part-10 mass parts are further more preferable.

<[C] Synthesis Method of Fluorine Atom-Containing Polymer>
[C] The fluorine atom-containing polymer can be synthesized, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator. In addition, as a polymerization initiator, a solvent, etc. which are used for the synthesis | combination of a [C] fluorine atom containing polymer, the thing similar to what was illustrated in the synthesis method of the said [A] polymer is mentioned.

  As reaction temperature in the said superposition | polymerization, it is 40 to 150 degreeC normally, and 50 to 120 degreeC is preferable. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  [C] The polystyrene equivalent weight average molecular weight (Mw) of the fluorine atom-containing polymer by GPC method is preferably 1,000 to 50,000, more preferably 1,000 to 30,000, and more preferably 1,000 to 10,000. 000 is more preferable. [C] When Mw of the fluorine atom-containing polymer is less than 1,000, the formed resist film surface may not be able to obtain a sufficient advancing contact angle. On the other hand, when Mw exceeds 50,000, the developability of the resulting photoresist composition tends to be lowered.

  [C] The Mw / Mn ratio of the fluorine atom-containing polymer is usually 1 to 3, and preferably 1 to 2.5.

<[D] Acid diffusion controller>
[D] The acid diffusion controller is a component that controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure and suppresses an undesirable chemical reaction in the unexposed area. When the photoresist composition contains the [D] acid diffusion controller, the storage stability of the obtained photoresist composition is further improved, and the resolution as a resist is further improved. In addition, it is possible to suppress a change in the line width of the resist pattern due to a change in the holding time from exposure to development processing, and a composition having extremely excellent process stability can be obtained. The content of the [D] acid diffusion controller is a free compound (hereinafter also referred to as “[D] acid diffusion controller”) or a form incorporated as a part of the polymer. Both of these forms may be used.

  [D] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4 -Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1, -Bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether Bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine, triethanolamine and the like can be mentioned.

  Examples of the amide group-containing compound include Nt-butoxycarbonyl group-containing amino compounds such as Nt-butoxycarbonyl-4-hydroxypiperidine, and Nt such as Nt-amyloxycarbonyl-4-hydroxypiperidine. -Amyloxycarbonyl group-containing amino compound, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N -Acetyl-1-adamantylamine, isocyanuric acid tris (2-hydroxyethyl) and the like.

  Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea and the like. Is mentioned.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 4-hydroxy-N-amyloxycarbonylpiperidine, piperidineethanol, 3-piperidino- 1,2-propanediol; morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, N- (2-cyclohexylcarbonyloxyethyl) morpholine, 3- (N-morpholino) -1, Morpholines such as 2-propanediol; 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane and the like.

  Of these, amide group-containing compounds and nitrogen-containing heterocyclic compounds are preferred, Nt-amyloxycarbonyl group-containing compounds and morpholines are more preferred, Nt-amyloxycarbonyl-4-hydroxypiperidine, N- (2-Cyclohexylcarbonyloxyethyl) morpholine is more preferred.

  In addition, as the [D] acid diffusion control agent, a photodegradable base that generates a weak acid by exposure can also be used. The photodegradable base generates an acid in the exposed portion to increase the insolubility of the [A] polymer in the developer containing the organic solvent, and as a result, the roughness of the exposed portion surface after development can be suppressed. On the other hand, in the unexposed area, a high acid capturing function by anions is exhibited and functions as a quencher, and the acid diffused from the exposed area is captured. That is, since it functions as a quencher only in the unexposed area, the contrast of the dissociation reaction of the acid dissociable group is improved, and as a result, the resolution can be further improved. Examples of the photodegradable base include an onium salt compound that decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (D1) and an iodonium salt compound represented by the following formula (D2).

In the formula (D1) and Formula ^(D2), independently R 10 ^{to R 14} are each a hydrogen atom, an alkyl group, an alkoxy group, hydroxy group, a halogen atom or _-SO 2 -R ^A. R ^A is an alkyl group, a cycloalkyl group, an alkoxy group or an aryl group. Z ⁻ and E ⁻ are OH ⁻ , R ^B —COO ⁻ , R ^C —SO ₂ —N ^— —R ^B , R ^B —SO ₃ ^— or an anion represented by the following formula (D3). R ^B is a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms. Some or all of the hydrogen atoms of the alkyl group, cycloalkyl group, aryl group and aralkyl group may be substituted. R ^C is a linear or branched alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms. Some or all of the hydrogen atoms of the alkyl group and cycloalkyl group may be substituted with fluorine atoms. However, when Z ⁻ is R ^B —SO ₃ ^— , a fluorine atom is not bonded to a carbon atom to which SO ₃ ^— is bonded.

In the above formula (D3), R ¹⁵ is a linear or branched alkyl group having 1 to 12 carbon atoms in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 to 12 carbon atoms. These are linear or branched alkoxy groups. u is an integer of 0-2.

The ^R 10 ^{to R 14} in the formula (D1) and (D2), hydrogen atom, _-SO 2 -R ^A is preferred. Moreover, as said ^RA , a cycloalkyl group is preferable and a cyclohexyl group is more preferable.

Examples of the alkyl group represented by R ^B include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, an i-butyl group, and a t-butyl group, and one of hydrogen atoms of these groups. Examples include groups in which part or all are substituted.

Examples of the cycloalkyl group represented by R ^B include, for example, a cyclopentyl group, a cyclohexyl group, a norbornyl group, a tricyclodecanyl group, a tetracyclododecanyl group, an adamantyl group, etc., and a part of hydrogen atoms of these groups or Examples include groups in which all are substituted.

Examples of the aryl group represented by R ^B, for example, a phenyl group, a naphthyl group, anthranyl group, and some or all of the hydrogen atoms of these groups and the like groups substituted.

Examples of the aralkyl group represented by R ^B include a benzyl group, a phenylethyl group, a phenylpropyl group, and a group in which some or all of the hydrogen atoms of these groups are substituted.

  As a substituent which the said alkyl group, a cycloalkyl group, an aryl group, and an alkaryl group have, a hydroxyl group, a halogen atom, an alkoxy group, a lactone group, an alkylcarbonyl group etc. are mentioned, for example.

Examples of the alkyl group represented by R ^C include a methyl group, an ethyl group, a propyl group, and a butyl group.

Examples of the cycloalkyl group represented by R ^C include a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.

  Examples of the photodegradable base include compounds represented by the following formulas.

  Among these, triphenylsulfonium salicylate and triphenylsulfonium 10-camphor sulfonate are preferable, and triphenylsulfonium 10-camphor sulfonate is more preferable.

  [D] The content of the acid diffusion controller is preferably 10 parts by mass or less with respect to 100 parts by mass of the polymer [A] when the [D] acid diffusion controller is a [D] acid diffusion controller. 0.1 mass part-7 mass parts are more preferable. [D] When the content of the acid diffusion controller exceeds 10 parts by mass, the sensitivity of the resulting photoresist composition may be lowered. [D] The acid diffusion inhibitor may be used alone or in combination of two or more.

<[E] solvent>
The above-mentioned photoresist composition usually contains an [E] solvent. [E] Solvent dissolves or disperses at least [A] polymer, [B] acid generator, [C] fluorine atom-containing polymer, [D] acid diffusion controller and other components contained as required If it can do, it will not specifically limit. [E] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and mixed solvents thereof.

  Examples of the solvent [E] include the same organic solvents listed in the step (3) in the fine pattern formation method described above. Of these, ester solvents and ketone solvents are preferable, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are more preferable. [E] The solvents may be used alone or in combination of two or more.

<Other ingredients>
The said photoresist composition can contain surfactant, an alicyclic skeleton containing compound, a sensitizer, etc. as other components other than said [A]-[E] component. In addition, the said photoresist composition may contain another arbitrary component individually by 1 type or 2 types or more, respectively.

[Surfactant]
The surfactant exhibits the effect of improving the coating property, striation, developability, and the like of the photoresist composition. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate, commercially available products such as KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFac F171, F173 (above, manufactured by Dainippon Ink & Chemicals), Fluorad FC430, FC431 ( As above, manufactured by Sumitomo 3M, Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industry) Manufactured) and the like.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has the effect of improving the dry etching resistance, pattern shape, adhesion to the substrate, and the like of the photoresist composition.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like.

[Sensitizer]
The sensitizer exhibits the effect of increasing the amount of acid generated from the [B] acid generator, and has the effect of improving the “apparent sensitivity” of the photoresist composition.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like.

<Method for preparing photoresist composition>
The photoresist composition includes, for example, an [A] polymer, a [B] acid generator, a [C] fluorine atom-containing polymer, a [D] acid diffusion controller, It can be prepared by mixing other components at a predetermined ratio. The prepared photoresist composition is preferably used after being filtered through, for example, a filter having a pore diameter of 20 nm. As solid content concentration of the said photoresist composition, 0.1 mass%-50 mass% are preferable, 0.5 mass%-30 mass% are more preferable, 1 mass%-15 mass% are more preferable.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The measuring method of each physical property value is shown below.

[ ¹³ C-NMR analysis]
The ¹³ C-NMR analysis of the polymer was performed using a nuclear magnetic resonance apparatus (JNM-EX270, manufactured by JEOL Ltd.) and DMSO-d ₆ as a measurement solvent.

<Synthesis of polymer>
The monomers used for the synthesis of [A] polymer and [C] fluorine atom-containing polymer are shown below.

  The compounds (M-1) to (M-4) are structural units (I), the compounds (M-7) to (M-11) are structural units (II), the compounds (M-5) and (M). −6) gives structural unit (III), and compounds (M-12) to (M-14) give structural unit (FI).

[[A] Synthesis of polymer]
[Synthesis Example 1]
12.9 g (50 mol%) of the above compound (M-1) and 17.1 g (50 mol%) of the compound (M-7) are dissolved in 30 g of 2-butanone, and azobisisobutyronitrile is used as a polymerization initiator. A monomer solution in which 0.5 g (AIBN) (5 mol% based on the total number of moles of the compound) was further dissolved was prepared. Next, 20 g of 2-butanone was charged into a 200 mL three-necked flask equipped with a thermometer and a dropping funnel, and the inside of this three-necked flask was purged with nitrogen for 30 minutes. After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring with a magnetic stirrer, and the monomer solution prepared above was added over 3 hours using a dropping funnel while maintaining the temperature. It was dripped. The polymerization reaction was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. After cooling, the polymerization reaction solution was poured into 400 g of n-hexane, and the precipitated white powder was filtered off. The filtered white powder was washed twice as a slurry in 80 g of n-hexane, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder polymer (A-1). This polymer (A-1) had Mw of 13,000 and Mw / Mn of 1.4. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from the compound (M-1) and the compound (M-7) was 50:50 (mol%).

[Synthesis Examples 2 to 6]
Polymers (A-2) to (A-5) in the same manner as in Synthesis Example 1, except that the types and amounts of monomers shown in Table 1 below and the amount of polymerization initiator (AIBN) used were used. And (a-1) were synthesized. In Table 1, “-” indicates that the corresponding monomer was not used. It shows according to Table 1 about the content rate of each structural unit in each said polymer synthesize | combined, Mw, and Mw / Mn.

[[C] Synthesis of fluorine atom-containing polymer]
[Synthesis Example 7]
21.5 g (70 mol%) of the above compound (M-2) and 8.5 g (30 mol%) of the compound (M-13) were dissolved in 60 g of 2-butanone to obtain dimethyl 2,2 ′ as a polymerization initiator. -A monomer solution was prepared by further dissolving 1.38 g of azobisisobutyrate (8 mol% based on the total number of moles of the compound). A 1,000 mL three-necked flask containing 30 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the monomer solution prepared above was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. After this polymerization reaction solution was transferred to a 2 L separatory funnel, the polymerization reaction solution was uniformly diluted with 150 g of n-hexane, and then 600 g of methanol was added and mixed. Next, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered to obtain a polymer (C-1) as a propylene glycol monomethyl ether acetate solution. This polymer (C-1) had Mw of 7,500 and Mw / Mn of 1.4. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from the compound (M-2) and the compound (M-13) was 70:30 (mol%).

[Synthesis Example 8]
In the same manner as in Synthesis Example 7 except that the types and amounts of monomers shown in Table 2 below and the amount of polymerization initiator (dimethyl 2,2′-azobisisobutyrate) were used, a polymer ( C-2) was synthesized. In Table 2, “-” indicates that the corresponding monomer was not used. It shows according to Table 2 about the content rate of each structural unit in each said polymer synthesize | combined, Mw, and Mw / Mn.

<Preparation of photoresist composition>
The [B] acid generator, [D] acid diffusion controller and [E] solvent constituting the photoresist composition are shown below.

[[B] acid generator]
B-1: Triphenylsulfonium 6- (1-adamantylcarbonyloxy) -1,1,2,2-tetrafluorohexane-1-sulfonate (compound represented by the following formula (B-1))
B-2: Triphenylsulfonium 2- (2-norbornyl) -1,1-difluoroethane-1-sulfonate (compound represented by the following formula (B-2))
B-3: 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate (compound represented by the following formula (B-3))

[[D] acid diffusion controller]
D-1: Triphenylsulfonium 10-camphorsulfonate (compound represented by the following formula (D-1))
D-2: Nt-amyloxycarbonyl-4-hydroxypiperidine (compound represented by the following formula (D-2))
D-3: N- (2-cyclohexylcarbonyloxyethyl) morpholine (compound represented by the following formula (D-3))

[[E] solvent]
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Synthesis Example 9]
[A] 100 parts by mass of (A-1) as a polymer, [B] 6.8 parts by mass of (B-1) as an acid generator, [C] (C-1) as a fluorine atom-containing polymer 3 parts by mass, (D-1) 3.9 parts by mass as an acid diffusion controller, (E-1) 2,110 parts by mass as an [E] solvent, (E-2) 900 parts by mass and (E-3) A photoresist composition (J-1) was prepared by mixing 30 parts by mass and filtering the resulting mixture with a filter having a pore size of 20 nm.

[Synthesis Examples 10-14]
Photoresist compositions (J-2) to (J-5) and (j-1) were prepared in the same manner as in Synthesis Example 9 except that the components of the types and blending amounts shown in Table 3 below were used.

<Formation of resist pattern>
A composition for forming an antireflection film (HM8006, manufactured by JSR) was applied onto a 12-inch silicon wafer as a substrate to be processed using a spin coater (CLEAN TRACK Lithius Pro i, manufactured by Tokyo Electron), and then applied at 60 ° C. at 60 ° C. An antireflection film having a thickness of 100 nm was formed by heating for 2 seconds. Next, a lower antireflection film-forming composition (ARC66, manufactured by Nissan Chemical Industries, Ltd.) was applied using the spin coater, and then heated at 205 ° C. for 60 seconds to form a lower antireflection film having a thickness of 105 nm. On this lower antireflection film, the above-prepared photoresist composition is applied using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron), PB at 90 ° C. for 60 seconds, and then cooled at 23 ° C. for 30 seconds. Thus, a resist film having a thickness of 90 nm was formed.
Next, using an ArF immersion exposure apparatus (NSR-S610C, manufactured by Nikon Seiki Company), exposure was performed under the conditions of numerical aperture = 1.30, dipole illumination, and best focus. The size on the reticle was 256 nm chrome / 512 nm pitch. After performing PEB for 60 seconds at the PEB temperature shown in Table 4 below, paddle development was performed at 23 ° C. for 30 seconds with the developer shown in Table 4, and then rinsed by paddle 10 seconds with the rinse liquid shown in Table 4. After performing, it dried and formed the negative resist pattern. In addition, TMAH of the developer indicates a 2.38 mass% tetramethylammonium hydroxide aqueous solution, and DIW of the rinse liquid indicates pure water (DeIonized Water).

<Evaluation>
The sensitivity of the prepared photoresist composition and the LWR and rectangularity of the formed resist pattern were evaluated according to the following methods. Table 4 shows the obtained results.

[sensitivity]
For each photoresist composition, the exposure amount at which the resist pattern to be formed had a size of 32 nm line and 128 nm pitch was defined as the optimum exposure amount, and this optimum exposure amount was defined as sensitivity (mJ / cm ² ).

[LWR]
The 32 nm line / 128 nm pitch line pattern resolved at the optimum exposure dose was observed from above the pattern using a scanning electron microscope (CG4000, manufactured by Hitachi High-Technologies Corporation). A total of 50 line widths of this line pattern were measured at arbitrary points, and a value calculated by setting the distribution degree of the measured values as 3 sigma was defined as LWR (nm).

[Rectangularity]
The cross-sectional shape of the line pattern of 32 nm line / 128 nm pitch resolved at the optimum exposure dose was observed using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies). The line width Lb at the intermediate height of the resist pattern and the line width La at the bottom of the resist pattern were measured. The rectangularity is “good” when 0.9 ≦ (La / Lb) ≦ 1.1, and “(La / Lb) <0.9 or 1.1 <(La / Lb)”. It was evaluated as “bad”.

<Inorganic pattern formation>
A plasma CVD apparatus (Dragon, manufactured by ASM) is used for each resist pattern formed above, and an inorganic layer made of silicon oxide having a flat film thickness of 30 nm is formed on the upper surface and side wall of the resist pattern by plasma CVD. Formed. Next, using a dry etching system (Telius SCCM, manufactured by Tokyo Electron), CF ₄ gas is turned into plasma, and the inorganic layer on the upper surface of the resist film is etched back (selectively removed) by reactive ion etching. The resist film was exposed. Subsequently, using the dry etching apparatus, the mixed gas of oxygen and nitrogen is turned into plasma, and only the exposed resist film of the substrate to be processed is removed by the same reactive ion etching method as described above. An inorganic pattern consisting of an inorganic layer deposited on the side wall of the pattern was obtained.

<Evaluation>
LWR about the formed inorganic pattern was evaluated according to the following method. The obtained results are shown in Table 4 together.
[LWR]
The formed inorganic pattern was observed from above the pattern using a scanning electron microscope (CG4000, manufactured by Hitachi High-Technologies). A total of 50 line widths of the inorganic pattern were measured at arbitrary points, and the value calculated by setting the distribution of the measured values as 3 sigma was defined as LWR (nm).

  As apparent from the results of Table 4, according to the fine pattern forming method of the example, the formed resist pattern has a small LWR and excellent rectangularity, and the formed inorganic pattern has a small LWR. can do. Therefore, it is considered that a pattern having a good shape can be formed on the substrate to be processed by using this method. On the other hand, as shown in the comparative example, when alkali development is used for forming a resist pattern, and when the photoresist composition contains a polymer that does not have a structural unit including a lactone structure or the like, an inorganic substance is formed. It can be seen that there is a disadvantage that the LWR of the pattern becomes large.

  According to the fine pattern forming method of the present invention, it is possible to provide a method of forming a good pattern on a substrate to be processed by forming a resist pattern and an inorganic pattern having a small LWR and a good shape. Therefore, the fine pattern forming method can be suitably used in the field of processing in semiconductor devices and the like that will be increasingly miniaturized in the future.

DESCRIPTION OF SYMBOLS 1 Substrate 1 'Substrate on which pattern is formed 2 Resist film 2' Resist pattern 3 Inorganic layer 3 'Part formed on side wall of resist pattern 3 "Inorganic pattern a Exposure light

Claims (3)

(1) A step of applying a photoresist composition on a substrate to be processed to form a resist film,
(2) a step of exposing the resist film;
(3) developing the exposed resist film using a developer containing an organic solvent to form a negative resist pattern;
(4) forming an inorganic layer so as to cover the resist pattern surface;
(5) Etching back the inorganic layer to remove a portion other than the portion formed on the sidewall of the resist pattern; and (6) Removing the resist pattern to form an inorganic pattern. ,
The photoresist composition is
[A] a polymer having a structural unit (I) containing an acid dissociable group and a structural unit (II) containing at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure, and [B] A method for forming a fine pattern containing an acid generator. (7) The method for forming a fine pattern according to claim 1, further comprising a step of dry etching the substrate to be processed using the inorganic pattern as a mask.   The fine pattern forming method according to claim 1, wherein the inorganic layer is formed by a CVD method or an ALD method.