JP2016075726A - Composition for forming finer resist pattern and pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming a finer resist pattern, from which a resist pattern having a fine and good profile and excellent etching durability can be easily formed.SOLUTION: The composition for forming a finer resist pattern comprises: a polymer that has a first structural unit including an aromatic ring having 6 to 20 carbon atoms and a second structural unit including a lactone ring, cyclic carbonate ring, sultone ring, alicycle with a hydroxy group bonded, or an alicycle with a carboxy group bonded, and has a weight average molecular weight of 10,000 or more and 150,000 or less; and a solvent. The second structural unit preferably includes a lactone ring, a cyclic carbonate ring or a sultone ring. A total content percentage of the first structural unit and the second structural unit is preferably 35 mol% or more with respect to the entire structural units constituting the polymer. A ratio of a content percentage of the first structural unit to a content percentage of the second structural unit is preferably 1/4 or more and 4/1 or less.SELECTED DRAWING: None

Description

  The present invention relates to a resist pattern refinement composition and a pattern forming method.

  With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, pattern miniaturization in the lithography process is required. In response to the above requirements, a pattern is formed by exposing and developing a resist film formed using a resist material containing a polymer whose solubility in a developing solution is changed by the action of an acid and a radiation-sensitive acid generator. In addition to the method, a method for further miniaturization based on the formed pattern has been studied.

  As such a method, a technique including a step of forming a crosslinked layer by causing a crosslinked layer forming material to act on the formed pattern (pre-pattern), crosslinking the resin constituting the pattern and the crosslinked layer forming material, is known. (See JP 2008-310314 A). However, since this technique forms a crosslinked layer, there is an inconvenience that the operation for miniaturization is complicated. Therefore, a simpler method has been demanded. As such a method, after applying a coating forming agent to the resist pattern, it is heated and applied to the developer without increasing the molecular weight on the resist pattern surface. A technique for forming a hardly soluble layer and increasing the thickness of a pattern has been studied (see JP 2013-117710 A). However, although this technique is considered to be a simpler method of miniaturization, in practice, it is considered difficult to obtain a fine pattern with a good shape, and has not yet satisfied the market demand. In addition, on the negative pattern, a film is formed using a composition containing a compound whose polarity is increased by the action of acid and its solubility in a removal solution containing an organic solvent is reduced. The technique to do is examined (refer Unexamined-Japanese-Patent No. 2013-257435). However, this technique has room for improvement in the etching resistance of the pattern.

JP 2008-310314 A JP2013-117710A JP2013-257435A

  The present invention has been made based on the circumstances as described above, and its purpose is to provide a resist pattern refinement composition that can easily form a resist pattern having a fine and good shape and excellent etching resistance, and It is to provide a pattern forming method.

  The invention made to solve the above problems includes a first structural unit containing an aromatic ring having 6 to 20 carbon atoms (hereinafter also referred to as “structural unit (A)”), a lactone ring, a cyclic carbonate ring, and a sultone ring. , Having a second structural unit (hereinafter also referred to as “structural unit (B)”) containing an alicyclic ring to which a hydroxy group is bonded or an alicyclic ring to which a carboxy group is bonded, and has a weight average molecular weight of 10,000 to 150,000. The following polymer (hereinafter also referred to as “polymer (I)”) and a resist pattern miniaturization composition (hereinafter also referred to as “composition (I)”) containing a solvent.

  Another invention made in order to solve the above problems is a process for forming a pre-pattern that is insoluble or hardly soluble in an organic solvent (hereinafter, also referred to as “pre-pattern forming process”), and a resin on at least the side surface of the pre-pattern. Step of forming a layer (hereinafter, also referred to as “resin layer forming step”) and heating the prepattern and the resin layer, the adjacent portion of the resin layer with the prepattern is not increased in molecular weight. A step of insolubilizing or hardly solubilizing in an organic solvent (hereinafter also referred to as “insoluble insolubilizing step”) and a step of removing a portion other than the insolubilized or hardly solubilized adjacent portion of the resin layer with the organic solvent (hereinafter referred to as “insoluble insolubilizing step”) A pattern forming method in which the resin layer is formed of the above-described resist pattern refinement composition.

  According to the resist pattern refinement composition and pattern formation method of the present invention, a resist pattern having a fine and good shape and excellent etching resistance can be formed by a simple method. Therefore, these can be suitably used for pattern formation in the field of semiconductor processing and the like that are expected to be further miniaturized in the future.

It is the schematic which shows one Embodiment of the pattern formation method of this invention.

<Composition for resist pattern refinement>
The resist pattern refinement composition is one that refines a resist pattern by thickening a previously formed pattern, thereby narrowing a pattern space portion or narrowing a pattern hole portion.

  The composition (I) includes a first structural unit containing an aromatic ring having 6 to 20 carbon atoms and a lactone ring, a cyclic carbonate ring, a sultone ring, an alicyclic ring to which a hydroxy group is bonded, or an alicyclic ring to which a carboxy group is bonded. A polymer (I) having a second structural unit and having a weight average molecular weight of 10,000 to 150,000, and a solvent. The composition (I) may contain a basic compound as a suitable component. Moreover, in the range which does not impair the effect of this invention, the other arbitrary component may be included.

The composition (I) can form a pattern having excellent etching resistance by including the polymer (I) having the structural unit (A) containing an aromatic ring having 6 to 20 carbon atoms. Moreover, a fine and favorable pattern can be formed by including the polymer (I) in a specific molecular weight range. This is considered to be because, for example, the adjacent layer formed in the insoluble slightly soluble process becomes more hardly soluble in the organic solvent used in the removing process.
Hereinafter, each component will be described.

(Polymer (I))
The polymer (I) includes a structural unit (A) and a structural unit (B). The polymer (I) may further have a structural unit other than the structural unit (A) and the structural unit (B). Preferably, the polymer (I) further has a structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (C)”). Preferably, the polymer (I) includes a structural unit containing a non-acid dissociable chain hydrocarbon group or a non-acid dissociable alicyclic hydrocarbon group (hereinafter also referred to as “structural unit (D)”). Also have. Preferably, the polymer (I) further has a structural unit containing a basic group. Hereinafter, each structural unit will be described.

[Structural unit (A)]
The structural unit (A) includes an aromatic ring having 6 to 20 carbon atoms.
Examples of the aromatic ring having 6 to 20 carbon atoms include a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring, and a biphenyl ring.
It is preferable that no polar group is bonded to the aromatic ring. Since the polar group is not bonded to the aromatic ring, the etching resistance of the resist pattern can be further increased. Examples of the polar group include a hydroxy group, an amino group, and a sulfanyl group.

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

In the formula, R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  As a minimum of the content rate of a structural unit (A), 35 mol% is preferable with respect to all the structural units which comprise polymer (I), and 50 mol% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable and 70 mol% is more preferable. By making the content rate of a structural unit (A) in the said range, the refinement | miniaturization characteristic of a pattern and an etching characteristic are excellent with sufficient balance.

[Structural unit (B)]
The structural unit (B) includes a lactone ring, a cyclic carbonate ring, a sultone ring, an alicyclic ring to which a hydroxy group is bonded, or an alicyclic ring to which a carboxy group is bonded. Examples of the structural unit (B) containing a lactone ring include structural units represented by the following formulas.

In the formula, R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

Examples of the structural unit (B) containing a cyclic carbonate ring include structural units represented by the following formulas. In the formula, R ² has the same meaning as described above.

As a structural unit (B) containing a sultone ring, the structural unit represented by a following formula etc. is mentioned, for example. In the formula, R ² has the same meaning as described above.

Examples of the structural unit (B) containing an alicyclic ring to which a hydroxy group is bonded or an alicyclic ring to which a carboxy group is bonded include a structural unit represented by the following formula. In the formula, R ² has the same meaning as described above.

  The structural unit (B) preferably contains a lactone ring, a cyclic carbonate ring or a sultone ring.

  As a minimum of the content rate of a structural unit (B), 20 mol% is preferable with respect to all the structural units which comprise polymer (I), and 30 mol% is more preferable. As an upper limit of the said content rate, 65 mol% is preferable and 50 mol% is more preferable. By making the content rate of a structural unit (B) into the said range, the refinement | miniaturization characteristic of a pattern and an etching characteristic are excellent with sufficient balance.

[Structural unit (C)]
Examples of the structural unit containing an acid dissociable group include a structural unit represented by the following formula (1). Since the polymer (I) has the structural unit (C), an adjacent layer is formed by the action of the acid contained in the pre-pattern, so that the pattern can be further refined.

The formula (1), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^p is a monovalent acid dissociable group.

The monovalent acid dissociable group represented by R ^p is preferably a group represented by the following formula (i).

In the above formula (i), R ^p1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^p2 and R ^p3 are each independently a monovalent chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are It represents an alicyclic structure having 3 to 20 ring members that is formed together with the carbon atoms to which they are bonded.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^p1 include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent alicyclic group having 3 to 20 carbon atoms. Examples include hydrocarbon groups and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and n-butyl. Group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclo Cycloalkyl groups such as octyl, cyclodecyl, cyclododecyl, norbornyl, adamantyl, tricyclodecyl, tetracyclododecyl;
And cycloalkenyl groups such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a cyclooctenyl group, a cyclodecenyl group, a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group and anthryl group;
Examples thereof include aralkyl groups such as benzyl group, phenethyl group, and naphthylmethyl group.

Among these, R ^p1 is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, and R ^ap group and cycloalkane constituted by carbon atoms to which R ^p2 and R ^p3 groups are combined and bonded to each other It is preferable to represent the structure.

  Examples of the structural unit (C) include structural units represented by the following formulas (1-1) to (1-4).

In the above formulas (1-1) to (1-4), R ³ 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.

  Examples of the structural unit represented by the above formula (1) or (1-1) to (1-4) include a structural unit represented by the following formula.

In said formula, R < ³ > is synonymous with the said Formula (1).

  Examples of the monomer that gives the structural unit (C) include (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, and (meth) acrylic acid- 2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- ( Bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1-methyl -1-cyclopentyl ester, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, ), And acrylic acid 1-ethyl-1-cyclohexyl ester.

  As a minimum of the content rate of a structural unit (C), 10 mol% is preferable with respect to all the structural units which comprise polymer (I), and 20 mol% is more preferable. As an upper limit of the said content rate, 60 mol% is preferable and 50 mol% is more preferable.

[Structural unit (D)]
Examples of the structural unit containing a non-acid-dissociable chain hydrocarbon group or a non-acid-dissociable alicyclic hydrocarbon group include those represented by the following formula.

In the above formula, R ⁴ represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^q is a group containing a non-acid-dissociable monovalent chain hydrocarbon group having 1 to 20 carbon atoms or a non-acid-dissociable monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms.

  Examples of the non-acid-dissociable monovalent chain hydrocarbon group having 1 to 20 carbon atoms include a methyl group, an n-butyl group, and an n-dodecyl group.

  Examples of the non-acid dissociable monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms include a cyclobutyl group and a cyclohexyl group.

  As a minimum of the content rate of a structural unit (D), 10 mol% is preferable with respect to all the structural units which comprise polymer (I), and 20 mol% is more preferable. As an upper limit of the said content rate, 60 mol% is preferable and 50 mol% is more preferable.

  The total content of the structural unit (A) and the structural unit (B) is preferably 35 mol% or more, more preferably 50 mol% or more with respect to all the structural units constituting the polymer (I). Preferably, it is 65 mol% or more.

  The ratio of the content ratio of the structural unit (A) to the content ratio of the structural unit (B) is preferably 1/4 or more, more preferably 1/3 or more, and 1/2 / 2.5 or more. More preferably. The ratio is preferably 4/1 or less, more preferably 3/1 or less, and further preferably 2.5 / 1 or less.

  The lower limit of the Mw of the polymer (I) is 10,000, preferably 15,000, more preferably 17,000, still more preferably 20,000, and particularly preferably 23,000. The upper limit of the Mw of the polymer (I) is 150,000, preferably 100,000, more preferably 80,000, still more preferably 50,000, and particularly preferably 30,000. When the Mw is less than 10,000, the shape of the pattern formed by the pattern forming method is deteriorated. On the other hand, when the Mw exceeds 150,000, it is difficult to prepare the composition (I).

(Method for synthesizing polymer (I))
The polymer (I) can be synthesized, for example, by polymerizing monomers giving each structural unit in a suitable solvent using a radical polymerization initiator.

  Examples of the radical polymerization initiator include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis ( 2-cyclopropylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), azo radical initiators such as dimethyl 2,2′-azobisisobutyrate; benzoyl peroxide, t- And peroxide radical initiators such as butyl hydroperoxide and cumene hydroperoxide. Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred. Two or more of these radical initiators may be used.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane; cyclohexane, cycloheptane, cyclooctane, decalin, norbornane, etc. Cycloalkanes; 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, methyl ethyl ketone, 4-methyl-2-pentanone and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes and diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. One or two or more of these solvents may be used.

  The reaction temperature in the polymerization is usually 40 ° C. or higher, preferably 50 ° C. or higher, and is usually 150 ° C. or lower, preferably 120 ° C. or lower. The reaction time is usually 1 hour or longer, while it is usually 48 hours or shorter, preferably 24 hours or shorter.

  As content of polymer (I), it is 70 mass% or more normally with respect to the total solid of composition (I), 80 mass% or more is preferable, and 85 mass% or more is more preferable.

(solvent)
Composition (I) contains a solvent. Examples of the solvent include organic solvents such as alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents.

Examples of the alcohol solvent include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, and 2-methylbutanol. , Sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethyl Hexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, s monoalcohol solvents such as ec-heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, 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.

Examples of the ether solvent include dialiphatic ethers such as diethyl ether, dipropyl ether, and dibutyl ether;
Diaromatic ethers such as diphenyl ether and ditolyl ether;
Examples thereof include aromatic-aliphatic ethers such as anisole and phenylethyl ether.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl amyl ketone, ethyl-n-butyl ketone, and methyl-n-hexyl ketone. Aliphatic ketone solvents such as di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone;
Aliphatic-aromatic ketone solvents such as acetophenone, propiophenone, tolylmethylketone;
Aromatic ketone solvents such as benzophenone, tolylphenyl ketone, and ditolyl ketone are listed.

Examples of the amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide. , N-methylpropionamide, N-methylpyrrolidone and the like.

Examples of the ester solvent 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, and acetic acid. 3-methoxybutyl, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, methoxytriglycol acetate, ethyl propionate Monoester solvents such as n-butyl propionate, iso-amyl propionate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate;
Diester solvents such as glycol diacetate, diethyl oxalate, di-n-butyl oxalate, diethyl malonate, dimethyl phthalate and diethyl phthalate;
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 ether Polyhydric alcohol monoether acetate solvents such as acetate, 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, dipropyl carbonate, ethylene carbonate, and propylene carbonate.

Examples of the hydrocarbon solvent include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, and cyclohexane. , Aliphatic hydrocarbon solvents such as methylcyclohexane;
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.

The composition (I) preferably satisfies at least one of the following (i) and (ii).
(I) Further containing a basic compound (ii) The polymer further has a structural unit containing a basic group.

  When composition (I) has basicity according to the above (i) or (ii), a finer and better-shaped pattern can be formed by using composition (I). This is because, for example, in the adjacent layer formed in the insoluble slightly soluble process described later, the acidic group such as a carboxy group of the polymer constituting the anionic property such as a carboxylate group depends on the basicity of the composition (I). Since it becomes a basis, it is considered that the adjacent layer is more hardly soluble in the organic solvent used in the removal step.

(Basic compound)
The basic compound is not particularly limited as long as it is a basic compound. For example, a compound represented by the following formula (X) (hereinafter also referred to as “compound (X)”) and the following formula (Y): At least one selected from the group consisting of the compounds represented (hereinafter also referred to as “compound (Y)”) is preferred.

In the above formula (X), X ⁺ is a monovalent onium cation. Y ⁻ is a monovalent carboxylate anion or a monovalent sulfonamide anion.
In the formula (Y), R ^X represents an unsubstituted or hydroxy-substituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms or an unsubstituted or hydroxy-substituted monovalent alicyclic carbon group having 3 to 20 carbon atoms. It is a hydrogen group. R ^Y and R ^Z are an unsubstituted or hydroxy-substituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms or an unsubstituted or hydroxy-substituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. Or an aliphatic heterocyclic structure having 3 to 20 ring members constituted by these groups being combined with each other and the nitrogen atom to which they are bonded.

Examples of the monovalent onium cation represented by X ⁺ include a sulfonium cation, an iodonium cation, an ammonium cation, and an oxonium cation.

Examples of the monovalent carboxylate anion represented by Y ⁻ include a salicylate anion.

Examples of the monovalent sulfonamide anion represented by Y ⁻ include trifluoromethylsulfonamide ion.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms and the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above R ^X , R ^Y and R ^Z include, for example, the above formula ( Examples thereof include the same groups as the groups exemplified as R ^p1 , R ^p2 and R ^{p3 in} i).

Examples of the aliphatic heterocyclic structure having 3 to 20 ring members composed of the R ^Y and R ^Z groups together with the nitrogen atom to which they are bonded include, for example, an azacyclopropane structure, an azacyclobutane structure, an azacyclopentane structure An azacycloalkane structure such as an azacyclohexane structure, an azacyclooctane structure, an azacyclodecane structure, an azanorbornane structure, an azaadamantane structure;
An azaoxacycloalkane structure such as an azaoxacyclopentane structure, an azaoxacyclohexane structure, an azaoxacyclooctane structure, an azaoxanorbornane structure;
Examples thereof include diazacyclopentane structures, diazacyclohexane structures, diazacyclooctane structures, diazacyclodecane structures, and diazacycloalkane structures such as diazanorbornane structures.

  Examples of the compound (X) include triphenylsulfonium salicylate and triphenylsulfonium n-butyltrifluoromethylsulfonamide.

  Examples of the compound (Y) include tri-n-pentylamine, tri-n-octylamine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine and the like.

  As a minimum of the compounding ratio of a basic compound, 1 mass% is preferred and 2 mass% is preferred to the total solid of composition (I). As an upper limit of a mixture ratio, 10 mass% is preferable and 5 mass% is preferable.

(Basic group)
The basic group of the structural unit containing a basic group is not particularly limited as long as it is a basic group. For example, the group represented by the following formula (a) (hereinafter also referred to as “group (a)”) ), A group represented by the following formula (b) (hereinafter also referred to as “group (b)”), and the like.

In said formula (b), L is a single bond, a C1-C20 bivalent chain hydrocarbon group, or a C3-C20 bivalent alicyclic hydrocarbon group. R ^A and R ^B are each independently a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. L and R ^A may be combined with each other to form an aliphatic heterocyclic structure having 3 to 20 ring members that is configured together with the nitrogen atom to which they are bonded.

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms represented by L include alkanediyl groups such as methanediyl group, ethanediyl group, and propanediyl group;
Alkenediyl groups such as ethenediyl group, propenediyl group, butenediyl group;
Examples include alkynediyl groups such as ethynediyl group, propenediyl group and butynediyl group.

Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by L include, for example, cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, cyclohexanediyl group, cyclooctanediyl group, cyclodecane A cycloalkanediyl group such as a diyl group, a norbornanediyl group, an adamantanediyl group;
And cycloalkenediyl groups such as cyclopropenediyl group, cyclopentenediyl group, cyclohexenediyl group and norbornenediyl group.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms and the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above R ^A and R ^B are represented by the above L. Examples include a group formed by adding one hydrogen atom to those exemplified as the divalent group.
R ^A and R ^B are preferably a hydrogen atom or a monovalent chain hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom or a methyl group.

Examples of the aliphatic heterocyclic structure having 3 to 20 ring members composed of L and R ^A together with the nitrogen atom to which they are bonded include, for example, an azacyclopropane structure, an azacyclobutane structure, an azacyclopentane structure, an aza A cyclohexane structure, an azacyclooctane structure, an azanorbornane structure, etc. are mentioned.

  Examples of the group (b) include amino group, aminomethyl group, methylamino group, methylaminomethyl group, dimethylamino group, dimethylaminomethyl group, diethylamino group, diethylaminopropyl group, pyrrolidin-1-yl group, pyrrolidine- 1-ylmethyl group, piperidin-1-yl group, piperidin-1-ylethyl group and the like can be mentioned.

  The structural unit containing a basic group is, for example, a structural unit in which a basic group is bonded to the main chain or side chain of the structural unit of the polymer (I) or a structural unit bonded to the end of the polymer (I). The polymer (I) may contain a structural unit containing two or more basic groups. The group (a) is preferably bonded to the terminal of the polymer (I). By bonding the group (a) to the terminal, the effect of the composition (I) can be exhibited while reducing the amount of the group (a) introduced into the polymer (I). Moreover, group (a) can be simply introduce | transduced into the terminal of polymer (I) by superposing | polymerizing using the radical polymerization initiator which has this group (a).

  When the polymer constituting the pre-pattern described later has an acid-dissociable group, the basic group and the basic compound include a conjugate base of an acidic group generated by dissociation of the acid-dissociable group. It is preferable that the basicity is higher. By using those having the above properties as the basic group and the basic compound, a pattern having a better shape can be formed according to the pattern forming method.

(Other optional ingredients)
Examples of other components that may be contained in the composition (I) include an acid proliferator and a surfactant.

(Acid breeder)
An acid proliferator is a component that is stable in the absence of an acid, but in the presence of an acid, it is decomposed by a catalytic reaction of this acid to produce a protonic acid. As the amount of the produced protonic acid increases, Since the decomposition reaction is accelerated, protonic acid can be grown and produced. By containing an acid proliferator in the composition (IA), a larger amount of acid is produced than this acid, for example, in the insoluble and slightly solubilized step described later, for example, acid diffused from the prepattern to the resin layer. Can be made. As a result, the adjacent layer with the pre-pattern of the resin layer can be more effectively insolubilized or hardly soluble. The form of the acid proliferator contained may be a form of a compound as will be described later (hereinafter also referred to as an “acid proliferator” as appropriate), a form incorporated as part of a polymer, or both of these forms.

  In order to induce degradation of the acid proliferator by the catalytic action of the generated acid, the acid dissociation constant (pKa) is preferably 3 or less, more preferably 2 or less as the strength of the acid generated. When a weak acid having a pKa exceeding 3 is generated, the decomposition of the acid proliferator tends to hardly proceed. The acid generated is preferably an organic sulfonic acid, such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, heptanesulfonic acid, octanesulfonic acid, cyclohexanesulfonic acid, camphorsulfone. Acid, trifluoromethanesulfonic acid, 2,2,2-trifluoroethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, p-bromobenzenesulfonic acid, p-nitrobenzenesulfonic acid, 2-thiophenesulfonic acid, 1- Naphthalenesulfonic acid and 2-naphthalenesulfonic acid are more preferable.

  As the acid proliferator, a compound in which a sulfonate group represented by the following formula (E) is bonded to a carbon atom forming a carbocyclic skeleton directly or via a divalent organic group is preferable.

In the above formula (E), R ^a is a monovalent organic group.

Examples of the monovalent organic group represented by R ^a include a chain organic group, an organic group having an alicyclic structure, an organic group having an aromatic ring structure, and an organic group having a heterocyclic structure. .

  The chain organic group is preferably an organic group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Unsubstituted alkyl group; unsubstituted acyl group such as formyl group, acetyl group, propionyl group and butyryl group; unsubstituted alkenyl group such as vinyl group and allyl group; unsubstituted group such as vinylcarbonyl group and allylcarbonyl group An alkenylcarbonyl group; a substituent of these groups, and the like.

  Examples of the organic group having the alicyclic structure include alicyclic hydrocarbon groups such as a cyclohexyl group, a cyclooctyl group, a bicyclohydrocarbon group, and a tricyclohydrocarbon group; and their substitutes.

  Examples of the organic group having an aromatic ring structure include aryl groups such as phenyl group and naphthyl group; aralkyl groups such as benzyl group, phenethyl group and naphthylmethyl;

  Examples of the organic group having a heterocyclic structure include a 5-membered ring compound containing one heteroatom such as furan, pyrrole, benzofuran, indole, and carbazole and a condensed ring compound thereof; including two heteroatoms such as oxazole and pyrazole. 5-membered ring compounds and condensed ring compounds thereof; 6-membered ring compounds containing one heteroatom such as pyran, pyrone, coumarin, pyridine, quinoline, isoquinoline, acridine and condensed ring compounds thereof; pyridazine, pyrimidine, pyrazine, phthalazine, etc. Examples thereof include a heterocyclic group derived from a heterocyclic compound such as a 6-membered ring compound containing two heteroatoms and a condensed ring compound thereof, and substituted products thereof.

  Examples of the substituent that gives a substituent of the above group include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, oxyhydrocarbon group, amino group, and substituted amino group.

  Examples of the compound having a sulfonate group represented by the above formula (E) include compounds represented by the following formula.

In the above formula, R ^a has the same meaning as the above formula (E). R ^b is a hydrogen atom, a chain-like monovalent organic group, a monovalent organic group having an alicyclic structure, or a monovalent organic group having an aromatic ring structure. R ^c is a chain-like monovalent organic group, a monovalent organic group having an alicyclic structure, or a monovalent organic group having an aromatic ring structure. L is a single bond or a divalent organic group.

As the chain organic group represented by R ^b and R ^c , the organic group having an alicyclic structure, and the organic group having an aromatic ring structure, each group represented by R ^a in the above formula (E) And the same groups as those exemplified above.

Among these, ^Rb is preferably a chain organic group, an organic group having an alicyclic structure, or an organic group having an aromatic ring structure.

The chain-like monovalent organic group represented by R ^c is preferably an alkyl group that may have a fluorine atom or a cycloalkyl group that may have a fluorine atom. Examples of these groups include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an n-pentyl group, a cyclopentyl group, an n-hexyl group, a cyclohexyl group, and an n-octyl group. Group, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluoro-t-butyl group, perfluoropentyl group, perfluorocyclopentyl group, perfluorohexyl group, perfluorocyclohexyl group, perfluorooctyl group, etc. Is mentioned.

  The divalent organic group represented by L is preferably a group represented by the following formula.

  Examples of the acid proliferating agent include compounds represented by the following formulas.

  As the content of the acid proliferator in the composition (I), from the viewpoint of more effective pattern miniaturization, when the acid proliferator is an acid proliferator, the amount of the polymer (I) is 100 parts by mass. 0 parts by mass or more is preferable, and 1 part by mass or more is preferable. On the other hand, it is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

(Method for adjusting composition (I))
The composition (I) can be prepared by mixing each component at a predetermined ratio according to a known method or the like.

<Pattern formation method>
Hereinafter, the pattern forming method of the present invention will be described with reference to FIG. The pattern forming method includes a pre-pattern forming step, a resin layer forming step, a hardly soluble insolubilizing step, and a removing step. The pattern formation method includes a basic compound and an organic solvent on at least the side surface of the prepattern after the prepattern formation step and before the resin layer formation step, and the solubility in the organic solvent is reduced by the action of an acid. It is preferable to further include a step (hereinafter, also referred to as “contacting step”) in which a composition that does not contain the polymer (hereinafter also referred to as “composition (II)”) is brought into contact. The pattern forming step may further include a step of rinsing with an organic solvent different from the organic solvent used in the removing step (hereinafter, also referred to as “rinsing step”) after the removing step. Hereinafter, each step will be described.

<Pre-pattern formation process>
This step is a step of forming a pre-pattern that is insoluble or hardly soluble in an organic solvent. By this step, a pre-pattern 2 is formed on the substrate 1 as shown in FIG. “Insoluble or hardly soluble in an organic solvent” means that the solubility in an organic solvent is small to such an extent that the shape of the pre-pattern is substantially maintained.

  As said organic solvent, the solvent similar to what was illustrated as an organic solvent which composition (I) contains is mentioned.

  Of these, ether solvents, ketone solvents, and ester solvents are preferred. As the ether solvent, an aromatic-aliphatic ether solvent is more preferable, and anisole is particularly preferable. As the ketone solvent, an aliphatic ketone solvent is more preferable, and methyl amyl ketone is particularly preferable. As the ester solvent, a monoester solvent is more preferable, and butyl acetate is particularly preferable. Two or more of these organic solvents may be used in combination.

  The prepattern preferably contains an acid. Since the pre-pattern contains an acid, the acid can act by diffusing from the pre-pattern to a resin layer described later, so that the pattern forming method can be performed more effectively.

  The pre-pattern forming step includes a polymer whose solubility in the organic solvent is reduced by the action of an acid (hereinafter also referred to as “[a] polymer”), a radiation sensitive acid generator (hereinafter referred to as “[b] acid”). Step of forming a resist film with a resist material containing a “generator” and a solvent (hereinafter also referred to as “[c] solvent”) (hereinafter also referred to as “resist film forming step”), and exposing the resist film And a step of developing the exposed resist film with a developer containing the organic solvent (hereinafter also referred to as “developing step”). By forming the pre-pattern by the method having the steps described above, it is possible to contain an acid generated from the acid generator [b] by exposure in the exposure step, and as a result, the pattern method can be made more effective. It can be carried out. Hereinafter, each step will be described.

[Resist film forming step]
In this step, a resist film is formed of a resist material containing [a] a polymer, [b] an acid generator, and [c] a solvent. This resist material will be described later.

  Examples of the substrate on which the resist film is formed include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate. Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. After application, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60 ° C. or higher, preferably 80 ° C. or higher, and is usually 140 ° C. or lower, preferably 120 ° C. or lower. The PB time is usually 5 seconds or more, preferably 10 seconds or more, while it is usually 600 seconds or less, preferably 300 seconds or less. The film thickness of the resist film to be formed is preferably 10 nm or more, while 1,000 nm or less is preferable, and 500 nm or less is more preferable.

  In order to prevent the influence of basic impurities and the like contained in the environmental atmosphere, a protective film disclosed in, for example, JP-A-5-188598 can be provided on the resist film. Further, in order to prevent the acid generator and the like from flowing out of the resist film, a liquid immersion protective film disclosed in, for example, JP-A-2005-352384 can be provided on the resist film. These techniques can be used in combination.

[Exposure process]
In this step, the resist film formed in the resist film forming step is exposed. The exposure is performed by irradiating radiation through a photomask (in some cases through an immersion medium such as water). Examples of the radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and γ-rays; charged particle beams such as electron beams and α-rays, depending on the line width of the target pattern. Among these, far ultraviolet rays and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm) and electron beams are more preferable, and ArF excimer laser light and electron beams are more preferable.

  The exposure method can be appropriately selected depending on the desired resist pattern shape and the like. For example, an isotrench pattern can be formed by exposing a desired region through an isoline pattern mask. Moreover, you may perform exposure twice or more. 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, it becomes easy to form a perfect circular contact hole pattern in the unexposed area surrounded by the exposed area.

  When the exposure is performed by immersion exposure, examples of the immersion liquid to be used 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 that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that reduces the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

  After the exposure, post-exposure baking (PEB) is performed, and in the exposed portion of the resist film, the acid-dissociable group of the [a] polymer or the like is dissociated by the acid generated from the [b] acid generator upon exposure. Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed area and the unexposed area. The temperature of PEB is usually 50 ° C. or higher, preferably 80 ° C. or lower, and is usually 180 ° C. or lower, preferably 130 ° C. or lower. The PEB time is usually 5 seconds or more, preferably 10 seconds or more, while it is 600 seconds or less, preferably 300 seconds or less.

[Development process]
In this step, the exposed resist film is developed with a developer containing the organic solvent. Thereby, a predetermined resist pattern is formed. After development, it is common to wash with water or a rinse solution such as alcohol and then dry.

  As an organic solvent which the said developing solution contains, the solvent similar to what was illustrated as an organic solvent which composition (I) contains, for example is mentioned. Of these, ether solvents, ester solvents, and ketone solvents are preferred. As the ether solvent, an aromatic-containing ether solvent is preferable, and anisole is more preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone solvent is preferable, and 2-heptanone is more preferable.

  As content of the organic solvent in a developing solution, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable, 99 mass% or more is especially preferable. By making content of the organic solvent in a developing solution into the said range, the contrast of an exposed part and an unexposed part can be improved. Examples of components other than the organic solvent include water and silicone oil.

  An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

  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.

  The resist film after the development is preferably washed with a rinse solution. An organic solvent can also be used as the rinsing liquid, and the generated scum can be washed efficiently. As the rinsing liquid, hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents and the like are preferable. Among these, alcohol solvents and ester solvents are preferable, and monovalent alcohol solvents having 6 to 8 carbon atoms are more preferable. Examples of monohydric alcohols having 6 to 8 carbon atoms include linear, branched or cyclic monohydric alcohols, such as 1-hexanol, 1-heptanol, 1-octanol, and 4-methyl-2-pentanol. 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, benzyl alcohol and the like. Of 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 said rinse liquid may be used independently and may use 2 or more types together. 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 within the above range, good development characteristics can be obtained. A surfactant can also be added to the rinse solution.

  As a cleaning treatment method using a rinsing liquid, for example, a method of continuously applying the rinsing liquid onto a substrate rotating at a constant speed (rotary coating method), or a method of immersing the substrate in a tank filled with the rinsing liquid for a certain period of time (Dip method), a method (spray method) of spraying a rinsing liquid on the substrate surface, and the like.

  Examples of the pre-pattern formed in this step include a line and space pattern and a hole pattern.

<Resist material>
The resist material contains [a] a polymer, [b] an acid generator, and [c] a solvent. In addition to the components [a] to [c], the resist material includes a polymer having a higher fluorine atom content than the [d] [a] polymer (hereinafter also referred to as “[d] polymer”) and [ e] An acid diffusion controller may be contained, or other components other than these may be contained. Hereinafter, each component will be described.

[[A] polymer]
[A] The polymer is a polymer whose solubility in the organic solvent is reduced by the action of an acid.
The above [a] polymer is not particularly limited as long as it has the above properties, and examples thereof include a polymer having an acid dissociable group (hereinafter also referred to as “[a ′] polymer”). The “acid-dissociable group” refers to a group that substitutes a hydrogen atom of an acidic group such as a carboxy group or a hydroxy group and dissociates by the action of an acid. By using the [a] polymer as the [a ′] polymer, a pattern with a better shape can be formed according to the pattern forming method.

(Structural unit (I))
The [a ′] polymer preferably has a structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (I)”). Examples of the structural unit (I) include the same structural unit as the structural unit (C).

  As a minimum of the content rate of structural unit (I), 30 mol% is preferable with respect to all the structural units which comprise a [a] polymer, and 35 mol% is more preferable. As an upper limit of the said content rate, 70 mol% is preferable and 65 mol% is more preferable. By making the content rate of structural unit (I) into the said range, according to the said pattern formation method, the resist pattern of a further favorable shape can be formed.

  The polymer [a] preferably has a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure, and has a structural unit (III) having a hydrophilic functional group. And may have other structural units other than the above structural units.

(Structural unit (II))
The structural unit (II) is a structural unit containing at least one 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 adhesion between the pre-pattern and the substrate is improved. As a result, according to the pattern forming method, a pattern having a better shape can be formed. it can. Examples of the structural unit (II) include structural units similar to those exemplified as the structural unit (B) containing a lactone ring, the structural unit (B) containing a cyclic carbonate ring, and the structural unit (B) containing a sultone ring. .

  As a minimum of the content rate of structural unit (II), 30 mol% is preferable with respect to all the structural units which comprise a [a] polymer, and 35 mol% is more preferable. As an upper limit of the said content rate, 70 mol% is preferable and 65 mol% is more preferable. By making the content rate of structural unit (II) into the said range, the pattern of a further favorable shape can be formed with the said pattern formation method.

(Structural unit (III))
The structural unit (III) is a structural unit (III) having a hydrophilic functional group. [A] Since the polymer has the structural unit (III), the adhesion between the pre-pattern and the substrate is improved. As a result, according to the pattern forming method, a pattern having a better shape can be formed. it can.

  Examples of the hydrophilic functional group include a hydroxy group, a carboxy group, an amino group, an oxo group (═O), a sulfonamide group, a cyano group, and a nitro group. Of these, a hydroxy group is preferred.

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

In the above formula, R ⁵ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  The content ratio of the structural unit (III) is preferably 0 mol% or more and 40 mol% or less, and more preferably 0 mol% or more and 30 mol% or less with respect to all the structural units constituting the [a] polymer. By making the content rate of structural unit (III) into the said range, according to the said pattern formation method, the resist pattern of a further favorable shape can be formed.

  [A] The polymer may have other structural units other than the above structural units. Examples of the other structural unit include a structural unit containing a non-acid dissociable alicyclic hydrocarbon group. The content ratio of the other structural units is preferably 0 mol% or more and 30 mol% or less, and more preferably 0 mol% or more and 20 mol% or less, based on all the structural units constituting the [a] polymer.

  [A] The content of the polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 85% by mass or more in the total solid content of the resist material.

  [A] The polymer can be synthesized, for example, by the same method as the synthesis method of the polymer (I).

  [A] The weight average molecular weight (Mw) of the polymer by gel permeation chromatography (GPC) is preferably 1,000 or more, more preferably 100,000 or less, more preferably 50,000 or less, and 30,000. The following are particularly preferred: [A] By making Mw of a polymer into the said range, according to the said pattern formation method, a pattern with a further favorable shape can be formed.

  [A] The ratio (Mw / Mn) between the Mw and the number average molecular weight (Mn) of the polymer is usually 1 or more and 3 or less, preferably 1 or more and 2 or less.

Mw and Mn of the polymer are values measured by GPC using Tosoh's GPC columns ("G2000HXL", "G3000HXL", "G4000HXL") under the following conditions.
Eluent: Tetrahydrofuran (Wako Pure Chemical Industries)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

[[B] Acid generator]
[B] The acid generator is a substance that generates an acid upon exposure. [A] The solubility of the polymer in the organic solvent is decreased by, for example, dissociating the acid dissociable group by the action of the acid generated by the [b] acid generator. As a result, a pre-pattern that is insoluble or hardly soluble in an organic solvent can be formed. Moreover, the said pre pattern can contain the acid generate | occur | produced by exposure from the [b] acid generator. As a result, according to the pattern forming method, a resist pattern having a fine and good shape can be formed more effectively. In the resist material, the [b] acid generator is contained in a low molecular compound form (hereinafter also referred to as “[b] acid generator” as appropriate) or in a form incorporated in the polymer. Both of these forms may be used.

  [B] Examples of the acid generator include onium salt compounds and N-sulfonyloxyimide compounds.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium 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 Phenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyl Diphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonyl Phenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafur Loethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) hexane-1-sulfonate, triphenylsulfonium 2- ( 1-adamantyl) -1,1-difluoroethanesulfonate and the like.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophene Ni-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 1- (6-n-butoxynaphthalen-2-yl) Torahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydro Thiophenium 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-4 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-hydroxy Phenyl) 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 [2.2 1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like.

Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy). ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2 , 3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoro-ethanone Sulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3 -Dicarboximide etc. are mentioned.

  [B] The acid generator is preferably an onium salt compound, and more preferably a sulfonium salt. [B] One or more acid generators may be used.

  [B] The content of the acid generator is usually 0.1 parts by mass or more per 100 parts by mass of the polymer [a] when the [b] acid generator is a [b] acid generator. The amount is preferably 0.5 parts by mass or more. On the other hand, it is usually 20 parts by mass or less, preferably 15 parts by mass or less. [B] When the content of the acid generator is less than the lower limit, the sensitivity and developability of the resist material may be lowered. On the other hand, when the content of the [b] acid generator exceeds the above upper limit, the transparency to radiation is lowered, and it may be difficult to obtain a desired resist pattern.

[[C] solvent]
[C] The solvent is not particularly limited as long as it can dissolve or disperse the [a] polymer, [b] acid generator and other components. [C] Examples of the solvent include the same solvents as those exemplified as the solvent contained in the composition (I).

  [C] Among these solvents, ester solvents and ketone solvents are preferable. As ester solvents, polyhydric alcohol monoether acetate solvents and lactone solvents are preferable, and propylene glycol monomethyl ether acetate and γ-butyrolactone are more preferable. As the ketone solvent, a cyclic ketone solvent is preferable, and cyclohexanone is more preferable.

[[D] polymer]
[D] The polymer is a polymer having a higher fluorine atom content than the [a] polymer. When the resist material contains the [d] polymer, the distribution tends to be unevenly distributed on the surface of the resist film due to the oil-repellent characteristics of the [d] polymer when the resist film is formed. As a result, when performing immersion exposure, it can suppress that an acid generator, an acid diffusion control agent, etc. elute to an immersion medium, and is preferable. Further, due to the water-repellent characteristics of this [d] polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. In addition, a fluorine atom content rate (mass%) can be calculated | required by calculating | requiring the structure of a polymer by measuring ¹³ C-NMR, ¹ H-NMR, IR spectrum, etc.

  [D] The polymer is not particularly limited as long as the fluorine atom content is higher than that of the [a] polymer, but preferably has a fluorinated alkyl group. [D] The polymer is formed by polymerizing using at least one monomer containing a fluorine atom in the structure. The monomer containing a fluorine atom in the structure includes a monomer containing a fluorine atom in the main chain, a monomer containing a fluorine atom in the side chain, a monomer containing a fluorine atom in the main chain and the side chain, etc. Is mentioned.

  Examples of the monomer containing a fluorine atom in the main chain include an α-fluoroacrylate compound, an α-trifluoromethyl acrylate compound, a β-fluoroacrylate compound, a β-trifluoromethyl acrylate compound, an α, β-fluoroacrylate compound, An α, β-trifluoromethyl acrylate compound, a compound in which a hydrogen atom of one or more kinds of vinyl sites is substituted with a fluorine atom or a trifluoromethyl group, and the like can be mentioned.

  Examples of the monomer containing a fluorine atom in the side chain include those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorine atom or a fluoroalkyl group or a derivative thereof, a fluoroalkyl group of acrylic acid or methacrylic acid, or Examples thereof include an ester compound having such a derivative group, a monomer in which the side chain of one or more olefins (site not including a double bond) is a fluorine atom, a fluoroalkyl group or a derivative group thereof.

  Examples of monomers containing fluorine atoms in the main chain and the side chain include α-fluoroacrylic acid, β-fluoroacrylic acid, α, β-fluoroacrylic acid, α-trifluoromethylacrylic acid, β-trifluoro. An ester compound having a fluoroalkyl group such as methylacrylic acid or α, β-trifluoromethylacrylic acid or a derivative group thereof, a compound in which hydrogen atoms of one or more kinds of vinyl sites are substituted with a fluorine atom or a trifluoromethyl group Monomer substituted with a fluorine atom or a fluoroalkyl group or a derivative thereof, a hydrogen atom bonded to a double bond of one or more alicyclic olefin compounds, a fluorine atom or a trifluoromethyl group, etc. And a monomer whose side chain is a fluoroalkyl group or a derivative group thereof. In addition, this alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  [D] As an aspect in which the polymer has a fluorine atom, the polymer preferably contains a structural unit (IV) represented by the following formula (F1).

In the formula (F1), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁷ is a linear or branched alkyl group having 1 to 6 carbon atoms having at least one fluorine atom, a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a derivative thereof. k is an integer of 1 to 3. However, when R ⁴ is a plurality, may be a plurality of R ⁴ is optionally substituted by one or more identical. A is a single bond or a (k + 1) -valent linking group.

  As the (k + 1) -valent linking group represented by A, for example, an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, a urethane group, carbonyloxy-di (oxycarbonyl) ethanediyl Group, carbonyloxy-di (oxycarbonyl) propanediyl group, tri (carbonyloxy) ethanediyl group, carbonyloxy-tri (oxycarbonyl) ethanediyl group, carbonyloxy-tri (oxycarbonyl) propanediyl group, tetra (carbonyloxy) And an ethanediyl group.

  Monomers that give the structural unit (IV) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, Fluoro n-propyl (meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro t -Butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylic acid ester, 1- (2,2,3,3,4,4, 5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic acid Stell, 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 and 2,2-di (2,2,2-trifluoroethyloxycarbonyl) ethyl (meth) acrylic acid ester are preferable, and 2,2,2-trifluoroethyl (meth) ) Acrylic acid ester and 2,2-di (2,2,2-trifluoroethyloxycarbonyl) ethyl (meth) acrylic acid ester are more preferred.

  [D] The polymer may have two or more structural units (IV). As a content rate of structural unit (IV), it is 5 mol% or more normally with respect to all the structural units in a [d] polymer, 10 mol% or more is preferable and 15 mol% or more is more preferable. If the content ratio of the structural unit (IV) is less than 5 mol%, a receding contact angle of 70 ° or more may not be achieved, and elution of an acid generator or the like from the resist film may not be suppressed.

  In addition to the structural unit (IV), the [d] polymer contains an acid dissociable group in order to control the dissolution rate in the developer, the structural unit (I) in the polymer, a lactone structure, and a cyclic structure. 1 or more types of other structural units, such as structural unit (II) in the said [a] polymer containing at least 1 sort (s) chosen from the group which consists of a carbonate structure and a sultone structure, and a structural unit containing an alicyclic hydrocarbon group can do.

  Examples of the structural unit containing the alicyclic hydrocarbon group include a structural unit represented by the following formula (F2).

In the above formula (F2), R ⁸ 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 hydrocarbon groups composed of alicyclic rings derived from cycloalkanes such as 0 ^2,7 ] dodecane and tricyclo [3.3.1.1 ^3,7 ] decane.

  As a content rate of said other structural unit, it is 90 mol% or less normally with respect to all the structural units which comprise a [d] polymer, and 80 mol% or less is preferable.

  [D] The content of the polymer is preferably 0.1 parts by mass or more and more preferably 1 part by mass or more with respect to 100 parts by mass of the [a] polymer. On the other hand, it is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less. [D] By setting the content of the polymer in the above range, the water repellency of the formed resist film surface can be increased more appropriately.

  [D] The method for synthesizing the polymer can be synthesized, for example, according to the same method as the method for synthesizing the polymer (I). [D] The Mw of the polymer is preferably 1,000 or more, on the other hand, preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 10,000 or less. [D] When the Mw of the polymer is less than 1,000, a sufficient advancing contact angle may not be obtained.

[[E] Acid diffusion controller]
[E] The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid etc. generated from the [b] acid generator by exposure, and has an effect of suppressing an undesirable chemical reaction in the non-exposed region. In addition, the [e] acid diffusion controller has an effect of improving the storage stability of the resist material containing the acid diffusion controller. [E] The content of the acid diffusion controller in the resist material may be a free compound (hereinafter also referred to as “[e] acid diffusion controller”) or a form incorporated as part of the polymer. Both of these forms may be used.

  [E] 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, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′ , N ″, N ″ -pentamethyldiethylenetriamine and the like.

  Examples of amide group-containing compounds include Nt-butoxycarbonyl group-containing amino compounds such as N- (t-butoxycarbonyl) -4-hydroxypiperidine, and N- (t-pentyloxycarbonyl) -4-hydroxypiperidine. Nt-pentyloxycarbonyl group-containing amino compound, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methyl Examples include pyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl).

  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, quinazoline, purine, pyrrolidine, piperidine, piperidineethanol, 2-quinoxalinol, 3-piperidino-1,2-propane. Diol, 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.

  [E] As the acid diffusion control agent, a photodegradable base which is sensitized by exposure and generates a weak acid can also be used. An example of a photo-disintegrating base includes 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 (K1) and an iodonium salt compound represented by the following formula (K2).

In the above formulas (K1) and (K2), R ^{9 to} R ¹³ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom. Z ^- and ^E - ^{are, OH -, R C -COO -} , R C -SO 3 -, R C -N - is an anion represented by _-SO 2 -R ^D or formula (K3). However, ^RC is an alkyl group, an aryl group, or an alkaryl group. ^RD is an alkyl group which may have a fluorine atom.

In said formula (K3), R < ¹⁴ > is a C1-C12 linear or branched alkyl group by which a part or all of a hydrogen atom may be substituted by the fluorine atom, or C1-C12 These are linear or branched alkoxy groups. u is an integer of 0-2.

[Other ingredients]
The resist material may contain other components other than the components [a] to [e]. Examples of the other components include surfactants and sensitizers.

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like. As the surfactant, the same surfactants as those used for general resist materials can be used.

(Sensitizer)
The sensitizer represents the action of increasing the amount of acid generated from the [B] acid generator, and has the effect of improving the “apparent sensitivity” of the resist material.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. Two or more of these sensitizers may be used in combination.

[Preparation method of resist material]
The resist material can be prepared, for example, by mixing [a] polymer, [b] acid generator, [c] solvent and a suitable component in a predetermined ratio. The total solid concentration of the resist material is usually 1% by mass or more and 50% by mass or less, and preferably 1% by mass or more and 25% by mass or less.

  In addition to the above-described method, the pre-pattern forming step includes, for example, a step of forming a resist film with the resist material and a step of exposing the resist film, followed by alkali development such as an aqueous tetramethylammonium hydroxide solution. It is also possible to perform a step of developing with a liquid and a step of exposing the entire surface of the developed resist film.

<Contact process>
This step is a step of bringing a composition (II) containing a basic compound and an organic solvent into the at least side surface of the prepattern and not containing a polymer whose solubility in the organic solvent is reduced by the action of an acid. . According to the pattern forming method, the shape of the pattern to be formed can be made better by having this contact step. For example, in the adjacent layer formed by contacting the composition (II) with at least the side surface of the prepattern, the basic compound adheres to the prepattern, and the subsequent resin layer forming step and insoluble hardly soluble step. A region where an acidic group such as a carboxyl group constituting this becomes an anionic group such as a carboxylate group is generated by the basic compound, and the adjacent layer is hardly soluble in an organic solvent used in the removal step. This is thought to be due to an increase in the degree.

  The basic compound contained in the composition (II) is not particularly limited as long as it is a basic compound. For example, the same compounds as those exemplified as the basic compound that may be contained in the composition (I) Etc.

  Examples of the organic solvent contained in the composition (II) include the same organic solvents as those contained in the composition (I).

  Examples of the polymer whose solubility in an organic solvent is reduced by the action of an acid not contained in the composition (II) include, for example, polymers similar to those exemplified as the [a] polymer in the prepattern forming step. It is done.

  The composition (II) may contain other components in addition to the basic compound and the organic solvent, and may contain, for example, a surfactant.

  As content of the basic compound in the said composition (II), 0.1 mass% or more and 10 mass parts or less are preferable, for example.

  Examples of the method of bringing the composition (II) into contact with at least the side surface of the prepattern include spin coating.

<Resin layer forming step>
This step is a step of forming a resin layer on at least the side surface of the pre-pattern. This resin layer is formed from the composition (I) described above. By this step, as shown in FIG. 1B, the resin layer 3 is formed on at least the side surface of the pre-pattern 2.

<Insoluble hardly soluble process>
This step is a step of making the adjacent portion of the resin layer adjacent to the prepattern insoluble or hardly soluble in the organic solvent without increasing the molecular weight by heating the prepattern and the resin layer. By this step, as shown in FIG. 1C, the adjacent layer 4 insoluble or hardly soluble in the organic solvent is formed in the resin layer 3 adjacent to the pre-pattern. “Without high molecular weight” means that there is no formation of a new covalent bond between the polymer constituting the pre-pattern and the polymer constituting the resin layer. Means substantially no increase. In this step, by heating the pre-pattern and the resin layer, for example, the acid contained in the pre-pattern diffuses into the adjacent portion of the resin layer with the pre-pattern, and the acid acts to exist in the adjacent portion. It is considered that the polymer to be insolubilized or hardly soluble in the organic solvent.

  Examples of the heating method include heating using a hot plate or the like. The heating temperature is preferably 50 ° C. or higher and 250 ° C. or lower. The heating time is preferably 10 seconds or longer and 10 minutes or shorter. The atmosphere for the heating may be any of inert gases such as nitrogen and argon in air.

<Removal process>
This step is a step of removing portions of the resin layer other than the adjacent layer with the organic solvent. Thereby, as shown in FIG. 1D, a miniaturized pattern can be obtained.

  The organic solvent used for the removal is not particularly limited as long as it does not dissolve the prepattern and the adjacent layer and dissolves the composition (I). For example, in the prepattern formation step, One or more of the exemplified organic solvents can be used, and the same organic solvent as that contained in the composition (I) can also be used.

<Rinse process>
This step is a step of rinsing with an organic solvent different from the organic solvent used in the removing step. The organic solvent used in this step is not particularly limited as long as it is different from the organic solvent used in the removal step. For example, one or more of the organic solvents exemplified in the prepattern may be used. it can. Among these organic solvents, an organic solvent having a lower polarity than the organic solvent used in the removal step is preferably used from the viewpoint of improving the shape of the obtained pattern.

  According to the pattern forming method, by performing the above steps, a resist pattern having a fine and good shape and excellent etching resistance can be formed by a simple method.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

<Synthesis of polymer>
The monomer compounds and polymerization initiators used in the synthesis of the [a] polymer and [d] polymer used for the preparation of the resist material and the polymer (I) used for the preparation of the pattern refinement composition are as follows. Show.

[[A] Synthesis of polymer]
[Synthesis Example 1] (Synthesis of polymer (A-1))
Compound (M-1) 40 mol%, Compound (M-2) 10 mol%, Compound (M-3) 40 mol%, Compound (M-4) 10 mol%, and Compound (Z- 1) A monomer solution in which 5 mol% was dissolved in 60 g of methyl ethyl ketone was prepared. In addition, mol% of each monomer compound is a ratio with respect to all the monomer compounds, and mol% of the polymerization initiator is a ratio with respect to the total number of moles of all the monomer compounds and the polymerization initiator. The total mass of the monomer compounds was adjusted to 30 g. Next, 30 g of methyl ethyl ketone was charged into a 500 mL three-necked flask equipped with a thermometer and a dropping funnel, and after purging with nitrogen for 30 minutes, the flask was heated to 80 ° C. while stirring with a magnetic stirrer. Subsequently, the monomer solution prepared above was dropped into a three-necked flask using a dropping funnel over 3 hours. The dropping start time was set as the polymerization reaction starting time, and the polymerization reaction was carried out for 6 hours. Thereafter, the polymerization reaction liquid was cooled to 30 ° C. or lower, and then this polymerization reaction liquid was put into 600 g of methanol, and the precipitated white powder was filtered off. The white powder separated by filtration was slurried twice with 120 g of methanol, washed separately, and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-1) (yield 23 .3 g, yield 77.6%). Mw of the polymer (A-1) was 6,200, and Mw / Mn was 1.62. As a result of ¹³ C-NMR analysis, the structural unit derived from (M-1) in the polymer (A-1): the structural unit derived from (M-2): the structural unit derived from (M-3): (M- The content ratio of the structural unit derived from 4) was 40.2: 9.0: 41.1: 9.7 (mol%), respectively.

[[D] Synthesis of polymer]
[Synthesis Example 2] (Synthesis of Polymer (D-1))
A monomer solution was prepared by dissolving 70 mol% of the compound (M-5), 30 mol% of the compound (M-6) and 8 mol% of the compound (Z-2) as a polymerization initiator in 100 g of methyl ethyl ketone. In addition, mol% of each monomer compound is a ratio with respect to all the monomer compounds, and mol% of the polymerization initiator is a ratio with respect to the total number of moles of all the monomer compounds and the polymerization initiator. The total mass of the monomer compounds was adjusted to 50 g. Next, a 500 mL three-necked flask containing 100 g of methyl ethyl ketone was purged with nitrogen for 30 minutes and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dropping start time was set as the polymerization reaction starting 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, washed with 825 g of a mixed solution of methanol / methyl ethyl ketone / hexane = 2/1/8 (mass ratio), and then propylene glycol monomethyl ether acetate. To obtain a solution containing the polymer (D-1) (polymer yield 38.0 g, yield 76.0%). Mw of the polymer (D-1) was 7,000, and Mw / Mn was 1.40. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-5) in the polymer (D-1) :( M-6) was 70.2: 29.8 (mol). %)Met.

[Synthesis of Polymer (I)]
[Synthesis Examples 3 to 17] (Synthesis of Polymers (I-1) to (I-15))
Polymers (I-1) to (I-15) were respectively synthesized in the same manner as in Synthesis Example 1 except that the types and amounts of monomer compounds and polymerization initiators shown in Table 2 below were used. Table 2 shows the Mw, Mw / Mn and yield of each polymer, and the content of each structural unit in each polymer. In addition, “-” in Table 2 indicates that the corresponding monomer compound was not used.

<Preparation of resist material>
[B] Acid generator, [c] solvent, and [e] acid diffusion controller used for the preparation of the resist material are shown below.

[[B] Acid generator]
B-1: Triphenylsulfonium 1,1-difluoro-2-((3-hydroxyadamantan-1-yl) methoxy) -2-oxoethanesulfonate (compound represented by the following formula (B-1))

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

[[E] Acid diffusion controller]
E-1: tert-pentyl 4-hydroxypiperidine-1-carboxylate (compound represented by the following formula (E-1))

[Preparation Example 1] (Preparation of resist material (J-1))
[A] 100 parts by mass of polymer (A-1) as polymer, [b] 7.8 parts by mass of acid generator (B-1) as acid generator, [c] solvent (C- 1) 2,510 parts by mass, solvent (C-2) 1,075 parts by mass and solvent (C-3) 30 parts by mass, [d] 3 parts by mass of polymer (D-1) as a polymer, and [e ] 0.8 parts by mass of the acid diffusion controller (E-1) as an acid diffusion controller was mixed to prepare a resist material (J-1).

<Preparation of pattern refining composition>
The [e] basic compound used for the preparation of the pattern refinement composition is shown below.

[[E] Basic compound]
E-2: Triphenylsulfonium salicylate (compound represented by the following formula (E-2))
E-3: Triphenylsulfonium n-butyltrifluoromethylsulfonamide (compound represented by the following formula (E-3))

[Preparation Example 2] (Preparation of pattern refinement composition (S-1))
100 parts by mass of (I-1) as polymer (I), 8 parts by mass of (E-2) as a basic compound and [c] 1914 parts by mass of (C-1) as a solvent and (C -2) 820 mass parts was mixed and the composition for pattern refinement | miniaturization (S-1) was prepared.

[Preparation Examples 3 to 16] (Preparation of Pattern Refinement Compositions (S-2) to (S-16))
Pattern refinement compositions (S-2) to (S-16) were prepared in the same manner as in Preparation Example 2, except that the components of the types and blending amounts shown in Table 4 below were used.

<Pattern formation>
[Example 1]
(Pre-pattern formation)
An antireflection film forming agent (“ARC66” manufactured by Nissan Chemical Industries, Ltd.) was spin-coated on a 12-inch silicon wafer using a coating / developing apparatus (“CLEAN TRACK Lithius Pro i” manufactured by Tokyo Electron), and then 205 A lower antireflection film having a film thickness of 105 nm was formed by baking at 60 ° C. for 60 seconds. The prepared resist material (J-1) is spin-coated on the substrate on which the lower antireflection film is formed using a coating / developing apparatus (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Co., Ltd.). After performing soft baking (SB) for 2 seconds, the resist film having a film thickness of 100 nm was formed by cooling at 23 ° C. for 30 seconds.

  Next, using an ArF immersion exposure apparatus (“NSR-S610C” manufactured by Nikon Seiki Co., Ltd.), a numerical aperture (NA) = 1.3 and an optical condition of 50 nm Reduced projection exposure was performed so that a 110 nm pitch pattern and a 55 nm hole / 600 nm pitch pattern were formed. After the exposure, post exposure baking (PEB) was performed at 95 ° C. for 60 seconds on the “CLEAN TRACK Lithius Pro i” hot plate, followed by cooling at 23 ° C. for 30 seconds.

  Next, development was performed using n-butyl acetate as a developer. Thereafter, spin drying was performed by shaking off at 2,000 rpm for 15 seconds to obtain pre-patterns of 50 nm holes / 110 nm pitch and 50 nm holes / 600 nm pitch.

(Pattern refinement)
Using a coating / developing apparatus (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Ltd.) on the prepattern, the pattern refinement composition (S-1) was spin coated to form a resin layer on the prepattern surface. This was baked at 150 ° C. for 60 seconds and then cooled at 23 ° C. for 30 seconds.

  Next, development was performed using n-butyl acetate as an organic solvent. Thereafter, spin drying was performed by shaking off at 2,000 rpm for 15 seconds.

[Examples 2 to 13 and Comparative Examples 1 to 4]
The same operation as in Example 1 was carried out except that (S-2 to S-16) was used as the pattern refinement composition. The used pattern refining composition, baking temperature and time are shown in Table 5 below.

<Evaluation>
About the obtained pattern, the dimension reduction amount of the hole pattern and the pattern type dependency were evaluated by the following methods. The obtained evaluation results are also shown in Table 5 below.

[Dimension reduction amount]
The hole pattern of the 110 nm pitch and the 600 nm pitch formed above is observed using a scanning electron microscope (“CG4000” of Hitachi High-Technologies Corporation), and the hole size of the pre-pattern and the pattern hole size after the pattern narrowing process Was measured and the difference was calculated, and this was taken as the size reduction amount (nm).

[Pattern type dependency]
In the evaluation of the dimensional reduction amount, the difference between the dimensional reduction amount in a hole with a 110 nm pitch and the dimensional reduction amount in a hole with a 600 nm pitch was defined as pattern type dependency (nm). The pattern type dependency was evaluated as “good” when it was less than 5 nm and “bad” when it was 5 nm or more.

[Etching resistance]
The etching rate of the composition for pattern miniaturization was evaluated, and those having a smaller etching rate than the resist material to be a pre-pattern were evaluated as “good” and those having a larger etching rate as “bad”.

[Judgment]
The case where the dimensional reduction amount was 10 nm or more at both 110 nm pitch and 600 nm pitch and the pattern type dependency was good was designated as “◯”, and the case where the dimensional shrinkage amount was less than 10 nm was designated as “X”.

  From Table 5, it can be seen that according to the resist pattern refinement composition and pattern formation method of the example, a resist pattern having a fine and good shape and excellent etching resistance can be formed by a simple method.

  According to the resist pattern refinement composition and pattern formation method of the present invention, a resist pattern having a fine and good shape and excellent etching resistance can be formed by a simple method. Therefore, these can be suitably used for pattern formation in the field of semiconductor processing and the like that are expected to be further miniaturized in the future.

1 Substrate 2 Pre-pattern 3 Resin layer 4 Adjacent layer

Claims (11)

A first structural unit including an aromatic ring having 6 to 20 carbon atoms and a second structural unit including a lactone ring, a cyclic carbonate ring, a sultone ring, an alicyclic ring to which a hydroxy group is bonded, or an alicyclic ring to which a carboxy group is bonded. And a resist pattern refinement composition comprising a polymer having a weight average molecular weight of 10,000 to 150,000, and a solvent.   The composition for refining a resist pattern according to claim 1, wherein the second structural unit includes a lactone ring, a cyclic carbonate ring, or a sultone ring.   3. The resist pattern miniaturization according to claim 1, wherein a total content ratio of the first structural unit and the second structural unit is 35 mol% or more with respect to all the structural units constituting the polymer. Composition.   The ratio of the content ratio of the first structural unit to the content ratio of the second structural unit is ¼ or more and 4/1 or less, for resist pattern refinement according to claim 1, claim 2, or claim 3. Composition.   The resist pattern refinement composition according to any one of claims 1 to 4, wherein a polar group is not bonded to the aromatic ring of the first structural unit.   The composition for refining a resist pattern according to any one of claims 1 to 5, wherein the polymer further has a structural unit containing an acid dissociable group.   The resist according to any one of claims 1 to 6, wherein the polymer further has a structural unit containing a non-acid dissociable chain hydrocarbon group or a non-acid dissociable alicyclic hydrocarbon group. Pattern refinement composition. The composition for refining a resist pattern according to any one of claims 1 to 7, which satisfies at least one of the following (i) and (ii).
(I) Further containing a basic compound (ii) The polymer further has a structural unit containing a basic group.   9. The resist pattern according to claim 1, wherein the resist pattern is miniaturized by reducing a pattern space portion or a pattern hole portion by increasing a thickness of a pre-formed pattern. 2. The resist pattern refinement composition according to item 1. Forming a pre-pattern that is insoluble or hardly soluble in an organic solvent;
Forming a resin layer on at least the side surface of the pre-pattern,
A step of insolubilizing or hardly solubilizing the organic solvent without increasing the molecular weight of the adjacent portion of the resin layer by heating the prepattern and the resin layer;
A step of removing a portion other than the adjacent portion insolubilized or hardly soluble in the resin layer with the organic solvent,
The pattern formation method in which the said resin layer is formed with the composition for resist pattern refinement | miniaturization of any one of Claim 1-9. After the pre-pattern formation step, before the resin layer formation step,
11. The method according to claim 10, further comprising a step of contacting a composition containing a basic compound and an organic solvent and not containing a polymer whose solubility in an organic solvent is reduced by the action of an acid on at least a side surface of the prepattern. Pattern forming method.

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