WO2023228692A1 - Copolymère, mélange de copolymères et composition de réserve positive - Google Patents

Copolymère, mélange de copolymères et composition de réserve positive Download PDF

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WO2023228692A1
WO2023228692A1 PCT/JP2023/017091 JP2023017091W WO2023228692A1 WO 2023228692 A1 WO2023228692 A1 WO 2023228692A1 JP 2023017091 W JP2023017091 W JP 2023017091W WO 2023228692 A1 WO2023228692 A1 WO 2023228692A1
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copolymer
group
formula
monomer
alkyl group
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PCT/JP2023/017091
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English (en)
Japanese (ja)
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学 星野
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日本ゼオン株式会社
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F212/02—Monomers containing only one unsaturated aliphatic radical
    • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F212/06—Hydrocarbons
    • C08F212/08—Styrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/22—Esters containing halogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F222/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
    • C08F222/10—Esters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F222/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
    • C08F222/10—Esters
    • C08F222/12—Esters of phenols or saturated alcohols
    • C08F222/18—Esters containing halogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/12—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
    • C08L25/02—Homopolymers or copolymers of hydrocarbons
    • C08L25/04—Homopolymers or copolymers of styrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur, or oxygen atoms in addition to the carboxy oxygen
    • C08L33/16—Homopolymers or copolymers of esters containing halogen atoms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor

Definitions

  • the present invention relates to a copolymer, a copolymer mixture, and a positive resist composition.
  • ionizing radiation such as electron beams and short wavelength light such as ultraviolet rays (hereinafter, ionizing radiation and short wavelength light may be collectively referred to as "ionizing radiation, etc.")
  • ionizing radiation and short wavelength light may be collectively referred to as "ionizing radiation, etc.”
  • Polymers whose main chains are cleaved by irradiation to increase their solubility in developing solutions are used as main chain cleavage type positive resists.
  • Patent Document 1 describes ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2 as a main chain-cleaved positive resist that has excellent sensitivity to ionizing radiation and heat resistance.
  • a positive resist made of a copolymer containing -trifluoroethyl units and ⁇ -methylstyrene units is disclosed.
  • the resulting resist pattern must be clear, that is, the boundary between the part where the resist film remains (residual film) and the part where the resist film has dissolved is clear. Clarity is required. Specifically, from the perspective of making it possible to form a resist pattern with higher clarity, the resist does not dissolve in the developer unless the irradiation amount reaches a certain amount; Having the characteristic that the main chain is broken and dissolved in the developer, that is, the magnitude of the slope of the sensitivity curve that indicates the relationship between the common logarithm of the irradiation dose of ionizing radiation, etc. and the residual film thickness of the resist after development. There is a need to increase the ⁇ value, which represents the
  • the present inventor conducted extensive studies in order to achieve the above object. Then, the present inventor newly discovered that the above problem can be solved by using a copolymer having three predetermined types of monomer units in a positive resist composition, and completed the present invention.
  • the present invention aims to advantageously solve the above-mentioned problems.
  • the present invention provides the following formula (I): [In formula (I), L 1 is a divalent linking group having a fluorine atom, Ar 1 is an aromatic ring group which may have a substituent, and X 1 is a halogen atom, a cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl ester group, or halogenated alkyl group.
  • Monomer unit (I) represented by the following formula (II) different from the monomer unit (I):
  • R 1 is an organic group having 3 to 10 fluorine atoms
  • X 2 is a halogen atom, cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl It is an ester group or a halogenated alkyl group.
  • R 2 is an alkyl group
  • R 3 is a hydrogen atom, a fluorine atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom
  • R 4 is a hydrogen atom
  • It is an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom
  • “may have a substituent” means "unsubstituted or has a substituent.”
  • the number of fluorine atoms in R 1 is preferably 5 or more.
  • the sensitivity of the copolymer to ionizing radiation and the like can be improved.
  • the number of fluorine atoms in L 1 is preferably 4 or more.
  • the number of fluorine atoms in L 1 is at least the above lower limit, the sensitivity of the copolymer to ionizing radiation and the like can be improved.
  • the total proportion of the monomer unit (I) and the monomer unit (II) is greater than the total proportion of the monomer unit (I) and the monomer unit (II) in the copolymer.
  • the monomer unit is 100 mol%, it is preferably 45 mol% or more and 70 mol% or less. If the total proportion of monomer units (I) and monomer units (II) is equal to or greater than the above lower limit when the total monomer units in the copolymer is 100 mol%, the resist pattern will be clear. You can improve your sexuality.
  • the resistant pattern can improve the ability to fall. Further, the amount of residue (hereinafter sometimes referred to as "resist residue") that remains unintentionally in the space portion of the resist pattern can be reduced.
  • the proportion of monomer units in the copolymer can be measured using a nuclear magnetic resonance (NMR) method such as 1 H-NMR.
  • the present invention aims to advantageously solve the above problems, and [5] the present invention includes a copolymer A and a copolymer B, and the copolymer A is A copolymer according to any one of the above [1] to [4], wherein the difference between the surface free energy of the copolymer B and the surface free energy of the copolymer A is 3 mJ/m 2 or more, It is a copolymer mixture. If the above-mentioned copolymer mixture is used, the pattern collapse resistance can be improved while ensuring the clarity of the resist pattern. Note that in this specification, "surface free energy" can be measured using the method described in the Examples of this specification.
  • the present invention aims to advantageously solve the above-mentioned problems, and [6] the present invention includes a copolymer A and a copolymer B, and the copolymer A is It is a copolymer of any one of the above [1] to [4], and the copolymer B has the following formula (IV):
  • L 2 is a divalent linking group having a fluorine atom
  • Ar 2 is an aromatic ring group which may have a substituent
  • X 3 is a halogen atom, a cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl ester group, or halogenated alkyl group.
  • R 5 is an alkyl group
  • R 6 is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group, or a halogenated carboxyl group
  • R 7 is It is a hydrogen atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom
  • It is a copolymer mixture having a monomer unit (V) represented by: If the above-mentioned copolymer mixture is used, the pattern collapse resistance can be improved while ensuring the clarity of the resist pattern.
  • the present invention aims to advantageously solve the above-mentioned problems, and [7] the present invention provides a positive-type product containing any one of the following (A) to (C) and a solvent. It is a resist composition.
  • A A copolymer according to any one of [1] to [4] above
  • B A copolymer A and a copolymer B, wherein the copolymer A is a copolymer according to any one of [1] to [4] above.
  • (C) a copolymer mixture in which the difference between the surface free energy of the copolymer B and the surface free energy of the copolymer A is 3 mJ/m 2 or more; It contains a polymer A and a copolymer B, the copolymer A is any of the copolymers of [1] to [4] above, and the copolymer B has the following formula (IV) : [In formula (IV), L 2 is a divalent linking group having a fluorine atom, Ar 2 is an aromatic ring group which may have a substituent, and X 3 is a halogen atom, a cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl ester group, or halogenated alkyl group.
  • L 2 is a divalent linking group having a fluorine atom
  • Ar 2 is an aromatic ring group which may have a substituent
  • X 3 is a halogen
  • R 5 is an alkyl group
  • R 6 is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group, or a halogenated carboxyl group
  • R 7 is It is a hydrogen atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom
  • the positive resist composition of [7] above preferably does not substantially contain components having a weight average molecular weight of less than 1000.
  • the clarity of the resist pattern can be improved if it does not substantially contain components having a weight average molecular weight of less than 1000.
  • the proportion (presence or absence) of "a component having a weight average molecular weight of less than 1000" can be measured using the method described in Examples.
  • substantially not containing means not actively blending except in cases where it is unavoidably mixed. Specifically, it means that the content of components having a weight average molecular weight of less than 1000 in the positive resist composition is less than 0.05% by mass.
  • the present invention it is possible to provide a copolymer that can improve the pattern collapse resistance while ensuring the clarity of the resist pattern. Further, according to the present invention, it is possible to provide a copolymer mixture that can improve the pattern collapse resistance while ensuring the clarity of the resist pattern. Further, according to the present invention, it is possible to provide a positive resist composition that can form a resist pattern with high pattern collapse resistance while ensuring clarity.
  • the copolymer of the present invention can be favorably used in a main chain cleavage type positive resist composition in which the main chain is cleaved by ionizing radiation or the like to reduce the molecular weight.
  • the copolymer mixture of the present invention contains the copolymer of the present invention, and can also be favorably used in a main chain cleavage type positive resist composition.
  • the positive resist composition of the present invention contains the copolymer of the present invention or the copolymer mixture of the present invention, and can be used, for example, to form a resist pattern in the manufacturing process of printed circuit boards such as build-up boards. It can be used on occasion.
  • the copolymer of the present invention has the following formula (I): [In formula (I), L 1 is a divalent linking group having a fluorine atom, Ar 1 is an aromatic ring group which may have a substituent, and X 1 is a halogen atom, a cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl ester group, or halogenated alkyl group.
  • R 1 is an organic group having 3 to 10 fluorine atoms
  • X 2 is a halogen atom, cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl It is an ester group or a halogenated alkyl group.
  • a monomer unit (II) represented by The following formula (III): [In formula (III), R 2 is an alkyl group, R 3 is a hydrogen atom, a fluorine atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom, R 4 is a hydrogen atom, It is an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom, p and q are integers from 0 to 5, and p+q 5. ] It has a monomer unit (III) represented by.
  • the copolymer of the present invention may contain any monomer units other than the monomer unit (I), the monomer unit (II), and the monomer unit (III), but the copolymer
  • the proportion of monomer units (I), monomer units (II) and monomer units (III) in all monomer units constituting the polymer is preferably 90 mol% or more in total. , 100 mol% (that is, the copolymer contains only monomer units (I), monomer units (II), and monomer units (III)).
  • the copolymer of the present invention has a monomer unit (I), a monomer unit (II), and a monomer unit (III), for example, a random copolymer, a block copolymer, It may be any ternary alternating copolymer, but preferably a ternary alternating copolymer.
  • a ternary alternating copolymer is an alternating copolymer in which monomer unit (I) or monomer unit (II) is copolymerized between monomer units (III). It is a combination. That is, schematically, each monomer unit is bonded like "-(III)-(I)-(III)-(II)-(III)-".
  • the copolymer of the present invention has predetermined monomer units (I), monomer units (II), and monomer units (III), so that when the irradiation amount of ionizing radiation etc. reaches a specific amount, , the main chain of the copolymer only in the irradiated portion is successfully cleaved, resulting in a lower molecular weight.
  • the components with lower molecular weights are well dissolved in the developer. This ensures the clarity of the resist pattern (ie, the ⁇ value is high). The reason for this is not clear, but the sensitivity to ionizing radiation, etc., and the irradiation of ionizing radiation, etc.
  • the copolymer of the present invention can improve pattern collapse resistance by having predetermined monomer units (I), monomer units (II), and monomer units (III). The reason for this is not clear, but the fluorine atoms in L 1 of monomer unit (I) and R 1 of monomer unit (II) improve the liquid repellency of the copolymer, which improves the resist pattern formation process. This is presumed to be due to the fact that it is possible to suppress the occurrence of tension between the patterns when removing the developer and rinse solution.
  • the copolymer of the present invention can suppress the generation of resist residue by having predetermined monomer units (I), monomer units (II), and monomer units (III). Although the reason for this is not certain, it is presumed that the aromatic ring group possessed by monomer unit (I) and monomer unit (III) improves the solubility in the developer.
  • the monomer unit (I) has the following formula (a): [In formula (a), L 1 , Ar 1 and X 1 are the same as in formula (I). ] is a structural unit derived from monomer (a).
  • Examples of the divalent linking group having a fluorine atom that can constitute L 1 in formula (I) and formula (a) include a divalent chain alkyl group having 1 to 5 carbon atoms and having a fluorine atom. can be mentioned.
  • examples of the divalent linking group having a fluorine atom include a trifluoromethylmethylene group, a pentafluoroethylmethylene group, and a bis(trifluoromethyl)methylene group. Among these, a pentafluoroethylmethylene group and a bis(trifluoromethyl)methylene group are preferred, and a bis(trifluoromethyl)methylene group is more preferred.
  • the number of fluorine atoms in L 1 is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and 10 or less. is preferable, and more preferably 7 or less.
  • the number of fluorine atoms in L 1 is equal to or greater than the above lower limit, the sensitivity to ionizing radiation and the like and the clarity of the resist pattern can be improved.
  • the number of fluorine atoms in L 1 is below the above upper limit, the production efficiency of the copolymer can be improved.
  • the aromatic ring group which may have a substituent and which may constitute Ar 1 in formula (I) and formula (a) includes an aromatic hydrocarbon ring group which may have a substituent, and , an aromatic heterocyclic group which may have a substituent.
  • the aromatic hydrocarbon ring group is not particularly limited, and examples thereof include a benzene ring group, a biphenyl ring group, a naphthalene ring group, an azulene ring group, an anthracene ring group, a phenanthrene ring group, a pyrene ring group, a chrysene ring group, Naphthacene ring group, triphenylene ring group, o-terphenyl ring group, m-terphenyl ring group, p-terphenyl ring group, acenaphthene ring group, coronene ring group, fluorene ring group, fluoranthrene ring group, pentacene ring group , perylene ring group, pentaphene ring group, picene ring group, pyrantrene ring group, and the like.
  • aromatic heterocyclic group examples include, without particular limitation, a furan ring group, a thiophene ring group, a pyridine ring group, a pyridazine ring group, a pyrimidine ring group, a pyrazine ring group, a triazine ring group, and an oxadiazole ring group.
  • triazole ring group imidazole ring group, pyrazole ring group, thiazole ring group, indole ring group, benzimidazole ring group, benzothiazole group, benzoxazole ring group, quinoxaline ring group, quinazoline ring group, phthalazine ring group, benzofuran ring group , a dibenzofuran ring group, a benzothiophene ring group, a dibenzothiophene ring group, a carbazole ring group, and the like.
  • the substituent that Ar 1 may have is not particularly limited, and examples thereof include an alkyl group, a fluorine atom, a fluoroalkyl group, and the like.
  • Examples of the alkyl group as a substituent that Ar 1 may have include chain alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, n-butyl group, and isobutyl group.
  • examples of the fluoroalkyl group as a substituent that Ar 1 may have include fluoroalkyl groups having 1 to 5 carbon atoms such as a trifluoromethyl group, a trifluoroethyl group, and a pentafluoropropyl group.
  • Ar 1 is preferably an aromatic hydrocarbon ring group that may have a substituent, and more preferably an unsubstituted aromatic hydrocarbon ring group. , a benzene ring group (phenyl group) is more preferred.
  • halogen atom that can constitute X 1 in formula (I) and formula (a) include chlorine atom, fluorine atom, bromine atom, iodine atom, and astatine atom.
  • alkylsulfonyl group that can constitute X 1 in formula (I) and formula (a) include methylsulfonyl group and ethylsulfonyl group.
  • alkoxy group that can constitute X 1 in formula (I) and formula (a) include methoxy group, ethoxy group, and propoxy group.
  • acyl group that can constitute X 1 in formula (I) and formula (a) include formyl group, acetyl group, propionyl group, and the like.
  • alkyl ester group that can constitute X 1 in formula (I) and formula (a) include a methyl ester group and an ethyl ester group.
  • halogenated alkyl group examples include a halogenated methyl group having 1 or more and 3 or less halogen atoms.
  • X 1 is preferably a halogen atom, more preferably a chlorine atom.
  • the monomer (a) represented by formula (a) is ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2,2, 2-trifluoroethyl (ACAFPh), ⁇ -chloroacrylate-1-phenyl-2,2,2-trifluoroethyl (ACAHFPh), and ⁇ -chloroacrylate-1-(4-methoxyphenyl)-1-
  • At least one monomer selected from the group consisting of trifluoromethyl-2,2,2-trifluoroethyl (ACAFPhOMe) is preferred, and ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2 ,2,2-trifluoroethyl is more preferred.
  • the copolymer contains ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl units, ⁇ -chloroacrylate-1-phenyl-2,2,2- At least one monomer selected from the group consisting of trifluoroethyl units and ⁇ -chloroacrylate-1-(4-methoxyphenyl)-1-trifluoromethyl-2,2,2-trifluoroethyl units It is preferable to have an ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl unit.
  • the proportion of monomer units (I) in the copolymer is preferably 1 mol% or more, and preferably 3 mol% or more, when the total monomer units in the copolymer is 100 mol%. More preferably, it is 5 mol% or more, still more preferably 8 mol% or more, preferably 40 mol% or less, more preferably 30 mol% or less, and preferably 20 mol% or less. It is more preferable, and even more preferably 15 mol% or less. If the proportion of monomer units (I) in the copolymer is equal to or higher than the above lower limit when the total monomer units in the copolymer is 100 mol%, the pattern collapse resistance of the resist pattern is improved. can. Furthermore, the amount of resist residue can be reduced.
  • the proportion of monomer units (I) in the copolymer is below the above upper limit when the total monomer units in the copolymer is 100 mol%, the sensitivity to ionizing radiation, etc. The clarity of the resist pattern can be improved.
  • the monomer unit (II) different from the monomer unit (I) has the following formula (b) different from the monomer (a): [In formula (b), R 1 and X 2 are the same as in formula (II). ] is a structural unit derived from the monomer (b) represented by
  • R 1 in formula (II) and formula (b) is an organic group having 3 or more and 10 or less fluorine atoms.
  • the number of fluorine atoms in R 1 is preferably 5 or more, more preferably 6 or more, even more preferably 7 or more, even more preferably 8 or more, and 9 or less. It is preferable that there be.
  • the number of fluorine atoms in R 1 is at least the above lower limit, sensitivity to ionizing radiation and the like and clarity of the resist pattern can be improved.
  • the number of fluorine atoms in R 1 is 8 or more, the production efficiency of the copolymer can be improved.
  • the number of carbon atoms in R 1 in formula (II) and formula (b) is preferably 2 or more and 10 or less, more preferably 5 or less. If the number of carbon atoms is at least the above lower limit, the solubility in the developer can be sufficiently improved. On the other hand, if the carbon number is below the above upper limit, the clarity of the resist pattern can be sufficiently ensured.
  • the organic group in R 1 preferably does not have an aromatic ring, and is more preferably chain-like.
  • organic groups include fluoroalkyl groups such as (b-1) to (b-31) below; fluoroalkoxyalkyl groups such as (b-32) to (b-55) below; Examples include fluoroalkoxyalkenyl groups such as ethoxyvinyl groups; and the like.
  • the organic group in R 1 is preferably a fluoroalkyl group, such as the fluoroalkyl group (2,2,2-trifluoroethyl group) in (b-13) and the fluoroalkyl group in (b-20).
  • fluoroalkyl group (2,2,3,3,3-pentafluoropropyl group), fluoroalkyl group (2,2,3,3,4,4,4-heptafluorobutyl group) of (b-25), or (b-31) is more preferably a fluoroalkyl group (2,2,3,3,4,4,5,5,5-nonafluoropentyl group), and 2,2,3,3,3- Pentafluoropropyl group, 2,2,3,3,4,4,4-heptafluorobutyl group, or 2,2,3,3,4,4,5,5,5-nonafluoropentyl group More preferably, it is a 2,2,3,3,4,4,4-heptafluorobutyl group or a 2,2,3,3,4,4,5,5,5-nonafluoropentyl group. is still more preferred, and 2,2,3,3,4,4,5,5,5-nonafluoropentyl group is even more preferred.
  • halogen atom that can constitute X 2 in formula (II) and formula (b) include a chlorine atom, a fluorine atom, a bromine atom, an iodine atom, an astatine atom, and the like.
  • alkylsulfonyl group that can constitute X 2 in formula (II) and formula (b) include a methylsulfonyl group and an ethylsulfonyl group.
  • alkoxy group that can constitute X 2 in formula (II) and formula (b) include methoxy group, ethoxy group, and propoxy group.
  • acyl group that can constitute X 2 in formula (II) and formula (b) include formyl group, acetyl group, propionyl group, and the like.
  • alkyl ester group that can constitute X 2 in formula (II) and formula (b) include a methyl ester group and an ethyl ester group.
  • halogenated alkyl group that can constitute X 2 in formula (II) and formula (b) include a halogenated methyl group having 1 or more and 3 or less halogen atoms.
  • X 2 is preferably a halogen atom, more preferably a chlorine atom, and even more preferably the same as X 1 .
  • monomer (b) represented by formula (b) includes, for example, ⁇ -chloroacrylic acid 2,2,2-trifluoroethyl (ACATFE), ⁇ -chloroacrylic acid 2,2 , 3,3,3-pentafluoropropyl (ACAPFP), ⁇ -chloroacrylic acid 3,3,4,4,4-pentafluorobutyl, ⁇ -chloroacrylic acid 2,2,3,3,4,4, 5,5,5-nonafluoropentyl, ⁇ -chloroacrylate 1H-1-(trifluoromethyl)trifluoroethyl, ⁇ -chloroacrylate 1H,1H,3H-hexafluorobutyl, ⁇ -chloroacrylate 1, ⁇ -chloroacrylics such as 2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl and 2,2,3,3,4,4,4-heptafluorobutyl ⁇ -chloroacrylate (ACAHF
  • ⁇ -chloroacrylic acid fluoroalkoxyalkenyl ester and the like.
  • ⁇ -chloroacrylic acid fluoroalkyl ester is preferred because it can improve sensitivity to ionizing radiation, etc.
  • ⁇ -chloroacrylic acid 2,2,2-trifluoroethyl ester, ⁇ -chloroacrylic acid 2,2,3 , 3,3-pentafluoropropyl, ⁇ -chloroacrylic acid 2,2,3,3,4,4,4-heptafluorobutyl, ⁇ -chloroacrylic acid 2,2,3,3,4,4, 5,5,5-nonafluoropentyl is more preferred, 2,2,3,3,3-pentafluoropropyl ⁇ -chloroacrylate, 2,2,3,3,4,4,4 ⁇ -chloroacrylate -heptafluorobutyl is more preferred, and ⁇ -chloroacrylic acid 2,2,3,3,4,4,4-heptafluorobutyl
  • the copolymer preferably has ⁇ -chloroacrylic acid fluoroalkyl ester units, ⁇ -chloroacrylic acid 2,2,2-trifluoroethyl units, ⁇ -chloroacrylic acid 2,2,3,3 , 3-pentafluoropropyl unit, ⁇ -chloroacrylic acid 2,2,3,3,4,4,4-heptafluorobutyl unit, and ⁇ -chloroacrylic acid 2,2,3,3,4,4 , 5,5,5-nonafluoropentyl units, and ⁇ -chloroacrylic acid 2,2,3,3,3-pentafluoro propyl unit, ⁇ -chloroacrylic acid 2,2,3,3,4,4,4-heptafluorobutyl unit, and ⁇ -chloroacrylic acid 2,2,3,3,4,4,5,5, It is more preferable to have at least one monomer unit selected from the group consisting of 5-nonafluoropentyl units, and ⁇ -chloroacrylic acid 2,2,
  • the proportion of monomer units (II) in the copolymer is preferably 10 mol% or more, and preferably 20 mol% or more, when the total monomer units in the copolymer is 100 mol%. More preferably, it is 30 mol% or more, still more preferably 35 mol% or more, preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less. It is more preferable, and even more preferably 45 mol% or less. If the proportion of the monomer unit (II) in the copolymer is equal to or higher than the above lower limit when the total monomer units in the copolymer is 100 mol%, the sensitivity to ionizing radiation etc. and the resist pattern can improve clarity.
  • the proportion of monomer units (II) in the copolymer is equal to or less than the above upper limit when the total monomer units in the copolymer is 100 mol%, the pattern collapse resistance of the resist pattern is can be improved. Furthermore, the amount of resist residue can be reduced.
  • the total proportion of monomer units (I) and monomer units (II) in the copolymer is 45 mol% or more when the total monomer units in the copolymer is 100 mol%. It is preferably at least 47 mol%, more preferably at most 70 mol%, even more preferably at most 60 mol%, even more preferably at most 55 mol%. If the total proportion of monomer units (I) and monomer units (II) in the copolymer is greater than or equal to the above lower limit, when the total monomer units in the copolymer is 100 mol%. , the clarity of the resist pattern can be improved.
  • the total proportion of monomer units (I) and monomer units (II) in the copolymer is 100 mol%, the total proportion of monomer units (I) and monomer units (II) in the copolymer is below the above upper limit. If so, the pattern collapse resistance can be improved. Furthermore, the amount of resist residue can be reduced.
  • the monomer unit (III) is represented by the following formula (c): [In formula (c), R 2 to R 4 and p and q are the same as in formula (III). ) is a structural unit derived from monomer (c).
  • the alkyl group that can constitute R 2 in formula (III) and formula (c) is not particularly limited, and includes alkyl groups having 1 or more and 5 or less carbon atoms. Among these, the alkyl group that can constitute R 2 is preferably a methyl group or an ethyl group.
  • the unsubstituted alkyl group that can constitute R 3 and R 4 in formula (III) and formula (c) is not particularly limited, and includes unsubstituted alkyl groups having 1 to 5 carbon atoms. .
  • the unsubstituted alkyl group that can constitute R 3 and R 4 is preferably a methyl group or an ethyl group.
  • the fluorine atom-substituted alkyl group that can constitute R 3 and R 4 in formula (III) and formula (c) is not particularly limited, and the alkyl group in which some or all of the hydrogen atoms in the alkyl group are substituted with Examples include groups having a structure substituted with a fluorine atom.
  • each R 3 may be the same or different from each other.
  • all of the plurality of R 3 and/or R 4 in formula (III) and formula (c) are hydrogen atoms or unsubstituted alkyl groups. It is preferably a hydrogen atom or an unsubstituted alkyl group having 1 or more and 5 or less carbon atoms, and even more preferably a hydrogen atom.
  • the monomer (c) represented by formula (c) is not particularly limited, and examples thereof include ⁇ -methylstyrene (AMS) such as the following monomers (c-1) to (c-11). ) and its derivatives (eg, 4-fluoro- ⁇ -methylstyrene: 4FAMS).
  • AMS ⁇ -methylstyrene
  • 4FAMS 4-fluoro- ⁇ -methylstyrene
  • the monomer (c) represented by the formula (c) is ⁇ -methylstyrene (c-1) or 4-fluoro- ⁇ -methylstyrene (c-2) is preferred, and ⁇ -methylstyrene is more preferred. That is, the copolymer preferably has an ⁇ -methylstyrene unit or a 4-fluoro- ⁇ -methylstyrene unit, and more preferably an ⁇ -methylstyrene unit.
  • the proportion of the monomer unit (III) in the copolymer is not particularly limited, and can be, for example, 30 mol% or more when the total monomer unit in the copolymer is 100 mol%. , preferably 40 mol% or more, more preferably 45 mol% or more, for example, it can be 70 mol% or less, preferably 60 mol% or less, more preferably 55 mol% or less, 53 mol% or less. % or less is more preferable.
  • the weight average molecular weight (Mw) of the copolymer is preferably 10,000 or more, more preferably 17,000 or more, even more preferably 25,000 or more, preferably 250,000 or less, and 180,000 or less. It is more preferable that it is 80,000 or less, even more preferably that it is 50,000 or less. If the weight average molecular weight (Mw) of the copolymer is at least the above-mentioned lower limit, it is possible to suppress the solubility of the resist film in the developer from increasing excessively with a low irradiation dose.
  • weight average molecular weight (Mw) of the copolymer is below the above upper limit, a positive resist composition can be easily prepared.
  • weight average molecular weight can be measured using the method described in Examples.
  • the number average molecular weight (Mn) of the copolymer is preferably 7,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, preferably 150,000 or less, and 100,000 or less. It is more preferable that it is 70,000 or less, even more preferably that it is 40,000 or less. If the number average molecular weight (Mn) of the copolymer is at least the above-mentioned lower limit, it is possible to further suppress the solubility of the resist film in the developing solution from increasing excessively at a low irradiation dose, resulting in a resist with further improved clarity. Can form patterns.
  • the number average molecular weight (Mn) of the copolymer is below the above upper limit, a positive resist composition can be prepared more easily.
  • the "number average molecular weight" can be measured as a standard polystyrene equivalent value using gel permeation chromatography.
  • the molecular weight distribution (Mw/Mn) of the copolymer is preferably 1.10 or more, more preferably 1.20 or more, even more preferably 1.45 or more, and 1.80 or less. It is preferably at most 1.70, more preferably at most 1.65, and even more preferably at most 1.65. If the molecular weight distribution (Mw/Mn) of the copolymer is at least the above lower limit, the ease of manufacturing the copolymer can be improved. On the other hand, if the molecular weight distribution (Mw/Mn) of the copolymer is below the above upper limit, the clarity of the resulting resist pattern can be further improved.
  • “molecular weight distribution” can be determined by calculating the ratio of weight average molecular weight to number average molecular weight (weight average molecular weight/number average molecular weight).
  • the surface free energy of the copolymer is preferably 18 mJ/m 2 or more, more preferably 19 mJ/m 2 or more, even more preferably 20 mJ/m 2 or more, and 27 mJ/m 2 or less. It is preferably 26 mJ/m 2 or less, more preferably 25 mJ/m 2 or less, even more preferably 24 mJ/m 2 or less, and even more preferably 22 mJ/m 2 or less. is even more preferable. Note that the surface free energy can be adjusted by changing the type and ratio of monomer units that constitute the copolymer.
  • the method for preparing the copolymer is not particularly limited.
  • a copolymer having monomer units (I), monomer units (II), and monomer units (III) is a copolymer having monomer units (a), monomers (b), , after polymerizing a monomer composition containing monomer (c) and any monomer copolymerizable with these monomers, the obtained copolymer is recovered and optionally It can be prepared by purification.
  • the composition, molecular weight distribution, number average molecular weight, and weight average molecular weight of the copolymer can be adjusted by changing the polymerization conditions and purification conditions.
  • the number average molecular weight and weight average molecular weight can be increased by lowering the polymerization temperature. Further, the number average molecular weight and weight average molecular weight can be increased by shortening the polymerization time. Furthermore, by purification, the molecular weight distribution can be made smaller.
  • the monomer composition used for preparing the copolymer includes, for example, monomer (a), monomer (b), monomer (c), and monomers copolymerizable with these monomers.
  • a mixture of a monomer component containing any monomer, an optionally usable solvent, an optionally usable polymerization initiator, and an optionally added additive can be used.
  • the monomer composition can then be polymerized using known methods. Among them, it is preferable to use cyclopentanone, water, etc. as the solvent. Further, as the polymerization initiator, it is preferable to use, for example, azobisisobutyronitrile.
  • the polymer obtained by polymerizing the monomer composition is not particularly limited. After adding a good solvent such as tetrahydrofuran to a solution containing the polymer, the solution to which the good solvent has been added is mixed with methanol, ethanol, It can be recovered by solidifying the polymer by dropping it into a poor solvent such as 1-propanol, 1-butanol, 1-pentanol, or hexane.
  • a good solvent such as tetrahydrofuran
  • the purification method used to purify the obtained polymer is not particularly limited, and includes known purification methods such as reprecipitation and column chromatography. Among these, it is preferable to use a reprecipitation method as a purification method. Note that the purification of the polymer may be repeated multiple times.
  • Purification of a polymer by the reprecipitation method can be carried out, for example, by dissolving the obtained polymer in a good solvent such as tetrahydrofuran, and then mixing the obtained solution with a good solvent such as tetrahydrofuran and methanol, ethanol, 1-propanol, 1- This is preferably carried out by dropping a portion of the polymer by dropping it into a mixed solvent with a poor solvent such as butanol, 1-pentanol, or hexane.
  • a good solvent such as tetrahydrofuran
  • the resulting copolymer can be purified by changing the types and mixing ratio of the good and poor solvents.
  • Molecular weight distribution, number average molecular weight and weight average molecular weight can be easily adjusted. Specifically, for example, the higher the proportion of the good solvent in the mixed solvent, the greater the molecular weight of the copolymer precipitated in the mixed solvent.
  • the copolymer When purifying a polymer by the reprecipitation method, the copolymer may be a polymer precipitated in a mixed solvent of a good solvent and a poor solvent, or a copolymer precipitated in a mixed solvent of a good solvent and a poor solvent, as long as it satisfies the desired properties.
  • a polymer that has not precipitated that is, a polymer that is dissolved in the mixed solvent
  • the polymer that did not precipitate in the mixed solvent can be recovered from the mixed solvent using a known method such as concentration to dryness.
  • the copolymer mixture of the present invention includes copolymer A and copolymer B, and optionally further includes a polymer other than copolymer A and copolymer B.
  • copolymer A is the copolymer of the present invention. Since the copolymer of the present invention can improve the pattern collapse resistance while ensuring the clarity of the resist pattern, the copolymer mixture of the present invention containing this copolymer also improves the clarity of the resist pattern. It is possible to improve the pattern collapse resistance while ensuring the same. Note that the copolymer mixture usually does not contain a solvent.
  • copolymer A As copolymer A, the copolymer of the present invention is used. Since the details of the copolymer of the present invention have been explained above, the explanation will be omitted here.
  • the content of copolymer A in the copolymer mixture is preferably 1% by mass or more, and preferably 5% by mass or more, when the total of all components of the copolymer mixture is 100% by mass. is more preferable, more preferably 10% by mass or more, even more preferably 15% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, 25% by mass or less. % or less is more preferable.
  • the proportion of copolymer A in the copolymer mixture is equal to or greater than the above lower limit, when the sum of all components of the copolymer mixture is 100% by mass, the clarity of the resist pattern can be improved.
  • copolymer B any copolymer can be used without particular limitation as long as it does not fall under the copolymer of the present invention and the main chain can be cleaved by irradiation with ultraviolet rays etc. be able to.
  • copolymers whose main chain is cleaved include copolymers described in JP-A No. 2022-65445.
  • copolymer B is a copolymer having (1) a surface free energy difference of 3 mJ/m2 or more with respect to copolymer A, or (2) a copolymer with a monomer unit (IV) described later and a monomer It is preferable to use a copolymer having the body unit (V).
  • copolymer B has a free energy difference of 3 mJ/m2 or more with copolymer A, and has a monomer unit (IV) and a monomer unit (V). It is more preferable to use
  • the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is 3 mJ/m 2 or more. If the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is 3 mJ/m2 or more , the pattern collapse resistance can be improved while ensuring the clarity of the resist pattern. .
  • the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is preferably 4 mJ/ m2 or more, more preferably 5.5 mJ/m2 or more , and 6 mJ/m2 or more.
  • the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is at least the above lower limit, the clarity of the resist pattern can be improved.
  • the difference in the surface free energy of copolymer B from the surface free energy of copolymer A is, for example, 14 mJ/m 2 or less, may be 13 mJ/m 2 or less, or may be 12 mJ/m 2 or less, It may be 11 mJ/m 2 or less.
  • the surface free energy of copolymer B may be larger or smaller than the surface free energy of copolymer A, but the surface free energy of copolymer B and the surface free energy of copolymer A are Since the difference between the The surface free energy of A) is preferred.
  • the surface free energy of copolymer B is preferably 28 mJ/m 2 or more, more preferably 29 mJ/m 2 or more, even more preferably 30 mJ/m 2 or more, and 35 mJ/m 2 or more. It is preferably 2 or less, more preferably 34 mJ/m 2 or less, and even more preferably 33 mJ/m 2 or less.
  • copolymer B has the following formula (IV): [In formula (IV), L 2 is a divalent linking group having a fluorine atom, Ar 2 is an aromatic ring group which may have a substituent, and X 3 is a halogen atom, a cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl ester group, or halogenated alkyl group.
  • a monomer unit (IV) represented by The following formula (V): [In formula (V), R 5 is an alkyl group, R 6 is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group, or a halogenated carboxyl group, and R 7 is It is a hydrogen atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom, r and s are integers from 0 to 5, and r+s 5.
  • the copolymer B has the monomer unit (IV) and the monomer unit (V), the pattern collapse resistance can be improved while ensuring the clarity of the resist pattern. Note that even if copolymer B contains any monomer units other than monomer unit (IV) and monomer unit (V) (excluding monomer unit (II)), however, the proportion of monomer units (IV) and monomer units (V) in all monomer units constituting copolymer B is preferably 90 mol% or more in total, and 100 mol% (that is, copolymer B contains only monomer units (IV) and monomer units (V)) is more preferable.
  • the copolymer B may be, for example, a random copolymer, a block copolymer, a ternary alternating copolymer, etc., but is preferably a ternary alternating copolymer.
  • the divalent linking group having a fluorine atom that can constitute L 2 in formula (IV) and formula (d) is a fluorine atom that can constitute L 1 in formula (I) and formula (a). Examples include groups similar to the divalent linking group having .
  • the aromatic ring group which may have a substituent and which may constitute Ar 2 in formula (IV) and formula (d) may constitute Ar 1 in formula (I) and formula (a). , and the same groups as aromatic ring groups which may have substituents.
  • halogen atom that can constitute X 3 in formula (IV) and formula (d) examples include the same groups as the halogen atom that can constitute X 1 in formula (I) and formula (a).
  • alkylsulfonyl group that can constitute X 3 in formula (IV) and formula (d) examples include the same groups as the alkylsulfonyl group that can constitute X 1 in formula (I) and formula (a). .
  • alkoxy group that can constitute X 3 in formula (IV) and formula (d) examples include the same groups as the alkoxy group that can constitute X 1 in formula (I) and formula (a).
  • Examples of the acyl group that can constitute X 3 in formula (IV) and formula (d) include the same groups as the acyl group that can constitute X 1 in formula (I) and formula (a).
  • alkyl ester group that can constitute X 3 in formula (IV) and formula (d) examples include the same groups as the alkyl ester group that can constitute X 1 in formula (I) and formula (a). .
  • halogenated alkyl group that can constitute X 3 in formula (IV) and formula (d) examples include the same groups as the halogenated alkyl group that can constitute X 1 in formula (I) and formula (a). Can be mentioned.
  • X 3 is preferably a halogen atom, more preferably a chlorine atom, and even more preferably the same as X 1 .
  • the proportion of monomer units (IV) in copolymer B is not particularly limited, and should be, for example, 30 mol% or more when the total monomer units in copolymer B is 100 mol%. It is preferably 40 mol% or more, more preferably 45 mol% or more, for example, it can be 70 mol% or less, preferably 60 mol% or less, and more preferably 55 mol% or less. .
  • the monomer unit (V) is represented by the following formula (e): [In formula (e), R 5 to R 7 and r and s are the same as in formula (V). ) is a structural unit derived from monomer (e).
  • the alkyl group that can constitute R 5 and R 6 in formula (V) and formula (e) is not particularly limited, and includes, for example, an unsubstituted alkyl group having 1 to 5 carbon atoms.
  • the alkyl group that can constitute R 5 and R 6 is preferably a methyl group or an ethyl group.
  • the halogen atom that can constitute R 6 in formula (V) and formula (e) is not particularly limited, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. Among these, a fluorine atom is preferred as the halogen atom.
  • the halogenated alkyl group that can constitute R 6 in formula (V) and formula (e) is not particularly limited, and includes, for example, a fluoroalkyl group having 1 to 5 carbon atoms.
  • the halogenated alkyl group is preferably a perfluoroalkyl group having 1 to 5 carbon atoms, and more preferably a trifluoromethyl group.
  • the unsubstituted alkyl group that can constitute R 7 in formula (V) and formula (e) is not particularly limited, and includes unsubstituted alkyl groups having 1 to 5 carbon atoms.
  • the unsubstituted alkyl group that can constitute R 7 is preferably a methyl group or an ethyl group.
  • the alkyl group substituted with a fluorine atom that can constitute R 7 in formula (V) and formula (e) is not particularly limited, and the alkyl group in which some or all of the hydrogen atoms in the alkyl group are replaced with a fluorine atom is not particularly limited. Examples include groups having a substituted structure.
  • R 6 and/or R 7 in formula (V) and formula (e) are all hydrogen atoms.
  • the monomer (e) represented by the formula (e) is not particularly limited, and examples thereof include ⁇ -methylstyrene (AMS) such as the following monomers (e-1) to (e-12). ) and derivatives thereof.
  • AMS ⁇ -methylstyrene
  • copolymer B preferably has ⁇ -methylstyrene units.
  • the proportion of monomer units (V) in copolymer B is not particularly limited, and may be, for example, 30 mol% or more when the total monomer units in copolymer B is 100 mol%. It is preferably 40 mol% or more, more preferably 45 mol% or more, for example, it can be 70 mol% or less, preferably 60 mol% or less, and more preferably 55 mol% or less. .
  • the weight average molecular weight (Mw) of copolymer B is preferably 100,000 or more, more preferably 125,000 or more, even more preferably 150,000 or more, preferably 600,000 or less, and 500,000 or less. It is more preferable that the number is 300,000 or less, and even more preferably 300,000 or less.
  • the number average molecular weight (Mn) of copolymer B is preferably 100,000 or more, more preferably 110,000 or more, preferably 300,000 or less, more preferably 200,000 or less, and 150,000 or less. It is even more preferable that there be.
  • the molecular weight distribution (Mw/Mn) of copolymer B is preferably 1.20 or more, more preferably 1.25 or more, even more preferably 1.30 or more, and 2.00 or less. It is preferable that it is, it is more preferable that it is 1.80 or less, and it is still more preferable that it is 1.60 or less.
  • the content of copolymer B in the copolymer mixture is preferably 60% by mass or more, and preferably 70% by mass or more, when the total of all components of the copolymer mixture is 100% by mass. is more preferable, more preferably 75% by mass or more, preferably 99% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, 85% by mass. It is even more preferable that it is the following. If the proportion of copolymer B in the copolymer mixture is equal to or greater than the above lower limit, when the sum of all components of the copolymer mixture is 100% by mass, sensitivity to ionizing radiation and the like can be improved. On the other hand, if the proportion of copolymer B in the copolymer mixture is equal to or less than the above upper limit when the sum of all components of the copolymer mixture is 100% by mass, the clarity of the resist pattern can be improved.
  • copolymer B having the above-mentioned monomer unit (IV) and monomer unit (V) includes monomer (d), monomer (e), and these monomers. It can be prepared by polymerizing a monomer composition containing a copolymerizable monomer, and then collecting the resulting copolymer and optionally purifying it.
  • the polymerization method and the purification method are not particularly limited, and can be the same as the method explained in the section of "Copolymer Preparation Method" above.
  • the polymerization method and purification method conventionally known methods such as suspension polymerization and solution polymerization can also be used.
  • a polymerization initiator may be used.
  • the positive resist composition of the present invention contains the copolymer of the present invention or the copolymer mixture of the present invention and a solvent, and optionally further contains known additives that can be incorporated into the resist composition.
  • the positive resist composition of the present invention contains, for example, any one of (A) to (C) shown below and a solvent.
  • (A) Copolymer of the present invention (B) Contains copolymer A and copolymer B, copolymer A is the copolymer of the present invention, and the surface free energy of copolymer B is , a copolymer mixture (C) containing copolymer A and copolymer B, the difference between which is 3 mJ/ m2 or more in surface free energy from copolymer A, and copolymer A is a copolymer according to the present invention.
  • Copolymer B is a copolymer of the following formula (IV):
  • L 2 is a divalent linking group having a fluorine atom
  • Ar 2 is an aromatic ring group which may have a substituent
  • X 3 is a halogen atom, a cyano group, alkylsulfonyl group, alkoxy group, nitro group, acyl group, alkyl ester group, or halogenated alkyl group.
  • a monomer unit (IV) represented by The following formula (V): [In formula (V), R 5 is an alkyl group, R 6 is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group, or a halogenated carboxyl group, and R 7 is It is a hydrogen atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom, r and s are integers from 0 to 5, and r+s 5. ] A copolymer mixture having a monomer unit (V) represented by
  • the copolymer of the present invention and the copolymer mixture of the present invention can improve the pattern collapse resistance while ensuring the clarity of the resist pattern.
  • a resist pattern with high pattern collapse resistance can be formed while ensuring clarity.
  • the positive resist composition of the present invention preferably does not substantially contain a component having a weight average molecular weight of less than 1000. Specifically, the positive resist composition preferably does not contain a component having a weight average molecular weight of less than 1000. The proportion is less than 0.05% by weight, preferably less than 0.01% by weight, more preferably less than 0.001% by weight. The clarity of the resist pattern can be improved if it does not substantially contain components having a weight average molecular weight of less than 1000.
  • the content of the copolymer in the positive resist composition is preferably 0.5% by mass or more, and preferably 1% by mass or more, when the total of all components of the positive resist composition is 100% by mass. It is more preferably 1.5% by mass or more, even more preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. preferable.
  • the content ratio of the copolymer mixture in the positive resist composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and 1.5% by mass or more, when the total of all components of the positive resist composition is 100% by mass. It is more preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less.
  • the solvent is not particularly limited as long as it can dissolve the copolymer of the present invention and copolymer A and copolymer B in the copolymer mixture.
  • Known solvents can be used, such as those described.
  • examples of the solvent include anisole, propylene glycol monomethyl ether acetate (PGMEA), cyclopentanone, and cyclohexanone.
  • PMEA propylene glycol monomethyl ether acetate
  • cyclopentanone cyclohexanone
  • the positive resist composition can be prepared by mixing the copolymer or copolymer mixture (copolymer A and copolymer B) of the present invention, a solvent, and known additives that can be optionally used. can.
  • the mixing method is not particularly limited, and any known method may be used.
  • the mixture may be prepared by mixing each component and then filtering the mixture.
  • the method for filtering the mixture is not particularly limited, and can be filtered using a filter, for example.
  • the filter is not particularly limited, and examples include fluorocarbon-based, cellulose-based, nylon-based, polyester-based, and hydrocarbon-based filtration membranes.
  • impurities such as metals may be mixed into the positive resist composition from metal piping, etc. that may be used during the preparation of the copolymer of the present invention and copolymer A and copolymer B in the copolymer mixture.
  • the materials constituting the filter include polyfluorocarbons such as polyethylene, polypropylene, polytetrafluoroethylene, and Teflon (registered trademark), and tetrafluoroethylene/perfluoroalkyl vinyl ether copolymers (PFA). ), nylon, and composite membranes of polyethylene and nylon are preferred.
  • polyfluorocarbons such as polyethylene, polypropylene, polytetrafluoroethylene, and Teflon (registered trademark), and tetrafluoroethylene/perfluoroalkyl vinyl ether copolymers (PFA).
  • nylon tetrafluoroethylene/perfluoroalkyl vinyl ether copolymers
  • nylon composite membranes of polyethylene and nylon are preferred.
  • a filter for example, the one disclosed in US Pat. No. 6,103,122 may be used.
  • a commercially available filter such as Zeta Plus (registered trademark) 40Q manufactured by CUNO Incorporated may be used.
  • the average particle size of the ion exchange resin is not particularly limited, but is preferably 2 ⁇ m or more and 10 ⁇ m or less.
  • cation exchange resins include sulfonated phenol-formaldehyde condensates, sulfonated phenol-benzaldehyde condensates, sulfonated styrene-divinylbenzene copolymers, sulfonated methacrylic acid-divinylbenzene copolymers, and Other types of sulfonic acid or carboxylic acid group-containing polymers may be mentioned.
  • the cation exchange resin is provided with H + counterions, NH 4 + counterions or alkali metal counterions, such as K + and Na + counterions.
  • the cation exchange resin preferably has a hydrogen counter ion.
  • Such cation exchange resins include Microlite® PrCH from Purolite, a sulfonated styrene-divinylbenzene copolymer with an H + counterion.
  • Such cation exchange resins are commercially available as AMBERLYST® from Rohm and Haas.
  • the pore size of the filter is preferably 0.001 ⁇ m or more and 1 ⁇ m or less. When the pore size of the filter is within the above range, it is possible to sufficiently prevent impurities such as metals from being mixed into the positive resist composition.
  • the resist pattern forming method includes a step of forming a resist film using the above-described positive resist composition of the present invention (resist film forming step), a step of exposing the resist film (exposure step), and a step of exposing the resist film to light.
  • the method includes at least a step of developing the resist film (developing step).
  • the resist pattern forming method may further include steps other than the above-described resist film forming step, exposure step, and development step.
  • the resist pattern forming method may include, before the resist film forming step, a step of forming a lower layer film on the substrate on which the resist film is formed (lower layer film forming step). Further, the resist pattern forming method may include a step of heating the exposed resist film (post-exposure bake (PEB) step) between the exposure step and the development step. Further, the resist pattern forming method may further include a step of removing the developer (developer removing step) after the developing step. After the resist pattern is formed by the resist pattern forming method, the method may further include a step of etching the underlying film and/or the substrate (etching step). In such a resist pattern forming method, since the positive resist composition of the present invention is used as the positive resist composition, a resist pattern with high pattern collapse resistance can be formed while ensuring clarity.
  • PEB post-exposure bake
  • a lower layer film is formed on the substrate.
  • the surface of the substrate is made hydrophobic. Thereby, the affinity between the substrate and the resist film can be increased, and the adhesion between the substrate and the resist film can be improved.
  • the lower layer film may be an inorganic lower layer film or an organic lower film.
  • the inorganic lower layer film can be formed by applying an inorganic material onto a substrate and performing baking or the like.
  • the inorganic material include silicon-based materials.
  • the organic lower layer film can be formed by applying an organic material onto the substrate to form a coating film and drying it.
  • the organic material is not limited to those that are sensitive to light or electron beams, and for example, resist materials and resin materials commonly used in the semiconductor field, liquid crystal field, etc. can be used.
  • the organic material is preferably a material that can form an organic lower layer film that can be etched, especially dry etched.
  • the organic material is preferably a material that can form an organic lower layer film that can be etched by oxygen plasma etching or the like. Examples of the organic material used to form the organic lower layer film include AL412 manufactured by Brewer Science.
  • the above-mentioned organic material can be applied by a conventionally known method using spin coating, a spinner, or the like.
  • the method for drying the coating film may be any method as long as it can evaporate the solvent contained in the organic material, such as baking.
  • the baking conditions are not particularly limited, but the baking temperature is preferably 80°C or more and 300°C or less, more preferably 200°C or more and 300°C or less.
  • the baking time is preferably 30 seconds or more, more preferably 60 seconds or more, preferably 500 seconds or less, more preferably 400 seconds or less, and preferably 300 seconds or less. It is more preferable, and particularly preferably 180 seconds or less.
  • the thickness of the lower layer film after drying the coating film is not particularly limited, but is preferably 10 nm or more and 100 nm or less.
  • the substrate on which the lower layer film or the resist film can be formed in the resist pattern forming method is not particularly limited, and includes an insulating layer and a copper foil provided on the insulating layer, which are used for manufacturing printed circuit boards, etc. and a mask blank in which a light-shielding layer is formed on the substrate, etc. can be used.
  • the material of the substrate examples include metals (silicon, copper, chromium, iron, aluminum, etc.), glass, inorganic materials such as titanium oxide, silicon dioxide (SiO 2 ), silica, and mica; nitrides such as SiN; Oxynitrides: Organic substances such as acrylic, polystyrene, cellulose, cellulose acetate, and phenolic resins may be mentioned. Among these, metal is preferable as the material of the substrate.
  • a cylindrical structure can be formed by using, for example, a silicon substrate, a silicon dioxide substrate, or a copper substrate, preferably a silicon substrate or a silicon dioxide substrate, as the substrate.
  • the size and shape of the substrate are not particularly limited. Note that the surface of the substrate may be smooth, may have a curved surface or an uneven shape, or may be a substrate in the shape of a flake.
  • the surface of the substrate may be subjected to surface treatment if necessary.
  • the surface of the substrate can be treated using a silane coupling agent that can react with the hydroxyl group. This changes the surface layer of the substrate from hydrophilic to hydrophobic, thereby increasing the adhesion between the substrate and the underlying film or between the substrate and the resist layer.
  • the silane coupling agent is not particularly limited, but hexamethyldisilazane is preferred.
  • the positive resist composition of the present invention is applied onto a workpiece such as a substrate to be processed using a resist pattern (on top of the lower film if a lower film is formed). , the applied positive resist composition is dried to form a resist film.
  • the method for applying and drying the positive resist composition is not particularly limited, and methods commonly used for forming resist films can be used. Among these, heating (prebaking) is preferred as the drying method. Further, from the viewpoint of improving the film density of the resist film, the prebaking temperature is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher.
  • the prebaking temperature is preferably 250°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower.
  • the pre-bake time is preferably 10 seconds or more, more preferably 20 seconds or more, and even more preferably 30 seconds or more. preferable.
  • the prebake time is preferably 10 minutes or less, more preferably 5 minutes or less, and even more preferably 3 minutes or less.
  • the resist film formed in the resist film forming step is irradiated with ionizing radiation or the like to draw a desired pattern.
  • a known drawing device such as an electron beam drawing device or an EUV exposure device can be used.
  • ⁇ Post-exposure bake process> In the post-exposure baking step, which can be performed optionally, the resist film exposed in the exposure step is heated. By performing a post-exposure baking step, the surface roughness of the resist pattern can be reduced.
  • the heating temperature is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, preferably 200°C or lower, and 170°C or lower. It is more preferable that the temperature is 150°C or less. When the heating temperature is within the above range, the surface roughness of the resist pattern can be favorably reduced while improving the clarity of the resist pattern.
  • the time for heating the resist film in the post-exposure baking step is preferably 10 seconds or more, more preferably 20 seconds or more, and even more preferably 30 seconds or more. If the heating time is 10 seconds or more, the surface roughness of the resist pattern can be sufficiently reduced while further improving the clarity of the resist pattern. On the other hand, from the viewpoint of production efficiency, the heating time is, for example, preferably 10 minutes or less, more preferably 5 minutes or less, and even more preferably 3 minutes or less.
  • the method of heating the resist film in the post-exposure baking step is not particularly limited, and examples include a method of heating the resist film with a hot plate, a method of heating the resist film in an oven, and a method of blowing hot air onto the resist film. .
  • the exposed resist film (or the exposed and heated resist film when a post-exposure bake step is performed) is developed to form a developed film on the workpiece.
  • the resist film can be developed by, for example, bringing the resist film into contact with a developer.
  • the method of bringing the resist film into contact with the developer is not particularly limited, and known methods such as immersing the resist film in the developer or applying the developer to the resist film can be used.
  • the developer can be appropriately selected depending on the properties of the copolymer of the present invention, and the properties of copolymer A and copolymer B in the copolymer mixture of the present invention. Specifically, when selecting a developer, it is preferable to select a developer that does not dissolve the resist film before the exposure process, but can dissolve the exposed portion of the resist film that has undergone the exposure process. Moreover, one type of developer may be used alone, or two or more types may be used in a mixture at an arbitrary ratio.
  • Examples of the developer include 1,1,1,2,3,4,4,5,5,5-decafluoropentane (CF 3 CFHCFHCF 2 CF 3 ), 1,1,1,2,2 ,3,3,4,4,5,5,6,6-tridecafluorohexane, 1,1,1,2,2,3,4,5,5,5-decafluoropentane, 1,1, Hydrofluorocarbons such as 1,3,3-pentafluorobutane, 1,1,1,2,2,3,3,4,4-nonafluorohexane, 2,2-dichloro-1,1,1-trifluoro Ethane, 1,1-dichloro-1-fluoroethane, 1,1-dichloro-2,2,3,3,3-pentafluoropropane (CF 3 CF 2 CHCl 2 ), 1,3-dichloro-1,1 , 2,2,3-pentafluoropropane (CClF 2 CF 2 CHClF) and other hydrochlorofluorocarbons, methyl non
  • the temperature of the developer during development is not particularly limited, but can be, for example, 5° C. or higher and 40° C. or lower. Further, the developing time can be, for example, 10 seconds or more and 4 minutes or less.
  • the developer removal step optionally included in the resist pattern forming method, the developer is removed from the developed resist film to form a resist pattern on the workpiece.
  • the developer can be removed by air blowing using a gas such as nitrogen, or by rinsing using a rinsing liquid.
  • the method of bringing the developed resist film into contact with the rinsing liquid is not particularly limited, and may include dipping the resist film in the rinsing liquid, applying the rinsing liquid to the resist film, etc. Known techniques can be used.
  • the rinsing liquid include, in addition to those similar to the developing liquids exemplified in the "Developing Step" section, hydrocarbon solvents such as octane and heptane, and water.
  • the rinsing liquid may contain a surfactant.
  • the temperature of the rinsing liquid during rinsing is not particularly limited, but can be, for example, 5° C. or higher and 40° C. or lower. Further, the rinsing time can be, for example, 5 seconds or more and 3 minutes or less.
  • the developer solution and rinse solution described above may each be filtered before use.
  • Examples of the filtration method include the filtration method using a filter as described in the above section of "Preparation of positive resist composition.”
  • the underlying film and/or substrate is etched using the above-described resist pattern as a mask to form a pattern on the underlying film and/or substrate.
  • the number of times of etching is not particularly limited, and may be one or more times.
  • the etching may be dry etching or wet etching, but dry etching is preferable. Dry etching can be performed using a known dry etching device. The etching gas used in dry etching can be appropriately selected depending on the elemental composition of the underlying film and substrate to be etched.
  • Etching gases include, for example, fluorine-based gases such as CHF 3 , CF 4 , C 2 F 6 , C 3 F 8 , SF 6 ; chlorine-based gases such as Cl 2 and BCl 3 ; O 2 , O 3 , H 2 O, etc.
  • Oxygen gas H2 , NH3 , CO , CO2, CH4 , C2H2 , C2H4 , C2H6 , C3H4 , C3H6 , C3H8 , HF , HI, HBr, HCl, NO, BCl 3 and other reducing gases; He, N 2 , Ar and other inert gases. These gases may be used alone or in combination of two or more.
  • an oxygen-based gas is normally used for dry etching of an inorganic lower layer film. Further, for dry etching of the substrate, a fluorine-based gas is usually used, and a mixture of a fluorine-based gas and an inert gas is preferably used.
  • the underlying film remaining on the substrate may be removed before or after etching the substrate.
  • the lower layer film may be a lower layer film with a pattern formed thereon, or may be a lower layer film without a pattern formed thereon.
  • the lower layer film may be removed by bringing a liquid such as a basic liquid or an acidic liquid, preferably a basic liquid, into contact with the lower layer film.
  • the basic liquid is not particularly limited, and includes, for example, alkaline hydrogen peroxide solution.
  • the method of removing the lower layer film by wet peeling using alkaline hydrogen peroxide solution is not particularly limited as long as the lower layer film and the alkaline hydrogen peroxide solution can be in contact for a certain period of time under heating conditions.
  • Examples include a method of immersing the base film in heated alkaline hydrogen peroxide solution, a method of spraying alkaline hydrogen peroxide solution onto the lower layer film in a heated environment, and a method of coating the lower layer film with heated alkaline hydrogen peroxide solution. After performing any of these methods, the substrate is washed with water and dried to obtain a substrate from which the underlying film has been removed.
  • the resist pattern forming method is not limited to the method shown in the following example.
  • An example of a resist pattern forming method is a resist pattern forming method using electron beam or EUV, which includes the above-mentioned lower layer film forming step, resist film forming step, exposure step, developing step, and developer removing step. including.
  • an example of the etching method uses a resist pattern formed by a resist pattern forming method as a mask, and includes an etching step.
  • an inorganic material is applied onto the substrate and baked to form an inorganic lower layer film.
  • the positive resist composition of the present invention is applied onto the inorganic lower layer film formed in the lower layer film forming step and dried to form a resist film.
  • the resist film formed in the resist film forming step is irradiated with EUV to draw a desired pattern.
  • the development step the resist film exposed in the exposure step is brought into contact with a developer to develop the resist film, thereby forming a resist pattern on the lower layer film.
  • the resist film developed in the development step is brought into contact with a rinsing solution to rinse the developed resist film.
  • the lower layer film is etched using the resist pattern as a mask to form a pattern on the lower layer film.
  • the substrate is etched using the patterned lower layer film as a mask to form a pattern on the substrate.
  • the resist film obtained by the above-described resist pattern forming method has excellent etching resistance, particularly dry etching resistance. Note that the higher the proportion of carbon content per unit volume of copolymer A and copolymer B in the copolymer of the present invention or the copolymer mixture of the present invention contained in the positive resist composition, , resist films tend to have excellent dry etching resistance.
  • the laminate obtained by the method for forming a resist pattern described above includes a substrate and a resist film formed on the substrate. Such a laminate can be suitably used as a printed circuit board.
  • the present invention will be specifically explained based on Examples, but the present invention is not limited to these Examples.
  • the proportion of monomer units in the copolymer, the number average molecular weight, weight average molecular weight, molecular weight distribution, and surface free energy of the copolymer were measured by the following methods. did. Here, the surface free energy was measured only for Examples 1, 2, 5, 10, and 11 and Preparation Examples 1 and 2.
  • the ⁇ value, Eth, pattern collapse resistance, and resist residue were measured or evaluated by the following methods.
  • the proportion of monomer units in the copolymer was calculated using 1 H-NMR method. Specifically, the copolymer obtained in the preparation example was dissolved in chloroform-d, 99.8% (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) to a concentration of 10% by mass, and this solution was subjected to a nuclear magnetic resonance apparatus. (manufactured by JEOL Ltd., 400 mHz), and the proportion of monomer units in the copolymer was calculated from the measurement results.
  • a spin coater manufactured by Mikasa Corporation, MS-A150
  • a spin coater manufactured by Mikasa Corporation, MS-A150
  • the irradiation amount of the electron beam was varied in steps of 4 ⁇ C/cm 2 within the range of 4 ⁇ C/cm 2 to 200 ⁇ C/cm 2 .
  • the thickness of the resist film in the drawn area was measured using an optical film thickness meter (Lambda Ace, manufactured by SCREEN Semiconductor Solutions Co., Ltd.), and the common logarithm of the total irradiation amount of the electron beam and the remaining thickness of the resist film after development were calculated.
  • the ⁇ value was determined using the following formula. The results are shown in Tables 2 and 3.
  • E 0 is the quadratic function obtained by fitting the sensitivity curve to a quadratic function in the range of residual film rate from 0.20 to 0.80 (normal use of residual film rate and total irradiation dose). It is the logarithm of the total irradiation amount obtained when a residual film rate of 0 is substituted for the function (function with logarithm).
  • ⁇ Eth> A resist film was formed on a silicon wafer in the same manner as the evaluation method of " ⁇ value".
  • the initial thickness T 0 of the obtained resist film was measured using an optical film thickness meter (Lambda Ace, manufactured by SCREEN Semiconductor Solutions).
  • the total electron beam irradiation amount Eth ( ⁇ C/cm 2 ) when the residual film rate of the straight line (approximate line of the slope of the sensitivity curve) obtained when calculating the ⁇ value becomes 0 was determined.
  • the results are shown in Tables 2 and 3. The smaller the value of Eth, the higher the sensitivity of the resist film and the higher the efficiency of forming a resist pattern.
  • Pattern collapse resistance was evaluated using the positive resist compositions obtained in Examples and Comparative Examples. Specifically, first, using a spin coater (manufactured by Mikasa, MS-A150), a positive resist composition was coated onto a silicon wafer having a diameter of 4 inches to a thickness of 50 nm. Next, the applied positive resist composition was heated on a hot plate at a temperature of 120° C. for 1 minute to form a resist film on the silicon wafer (resist film forming step). The thickness of the resist film was 50 nm.
  • the resist film was exposed to light at an optimum exposure dose (Eop) using an electron beam drawing device (manufactured by Elionix Co., Ltd., ELS-S50) to draw a pattern (exposure step).
  • the exposed resist film was heated for 1 minute on a 90° C. hot plate (post-exposure baking step).
  • post-exposure baking step the resist film was developed using isopropyl alcohol (IPA) as a developer at a temperature of 23° C. for 1 minute (development step). Thereafter, the developer was removed by nitrogen blowing to form a resist pattern (developer removal step). Then, the presence or absence of pattern collapse of the formed resist pattern was observed.
  • IPA isopropyl alcohol
  • Resist residue was evaluated using the positive resist compositions obtained in Examples and Comparative Examples. Specifically, first, a positive resist composition was applied onto a silicon wafer with a diameter of 4 inches using a spin coater (manufactured by Mikasa Corporation, MS-A150). Next, the applied positive resist composition was heated on a hot plate at a temperature of 180° C. for 3 minutes to form a resist film with a thickness of 40 nm on the silicon wafer (resist film forming step). Then, the resist film was exposed to light at an optimum exposure dose (Eop) using an electron beam drawing device (manufactured by Elionix Co., Ltd., ELS-S50) to draw a pattern (exposure step).
  • Eop exposure dose
  • ELS-S50 electron beam drawing device
  • a development process was performed for 1 minute at a temperature of 23° C. using isopropyl alcohol (IPA) as a developer (development step).
  • IPA isopropyl alcohol
  • a fluorinated solvent manufactured by 3M, Novec (registered trademark) 7100, methyl nonafluorobutyl ether, freezing point: -135°C, boiling point: 61°C
  • a resist pattern was formed by rinsing for seconds (developer removal step).
  • the resist pattern was observed using a scanning electron microscope (SEM) at a magnification of 100,000 times, and the amount of residue remaining in the resist pattern was evaluated according to the following criteria.
  • Example 1 ⁇ Preparation of copolymer> 0.7207 g of ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl (ACAFPh) as monomer (a) and ⁇ as monomer (b) -2.5004 g of 2,2,3,3,4,4,4-heptafluorobutyl chloroacrylate (ACAHFB) and 3.0000 g of ⁇ -methylstyrene as monomer (c) (total of ACAFPh and ACAHFB) (equivalent to about 2.34 equivalents when 1 equivalent), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.5565 g of cyclopentanone as a solvent.
  • ACAFPh ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl
  • ACAHFB 2,2,3,3,4,4,4-heptafluorobut
  • A1 was placed in a glass container, the glass container was sealed and replaced with nitrogen, and the mixture was stirred in a constant temperature bath at 78° C. for 6 hours under a nitrogen atmosphere. Thereafter, the temperature was returned to room temperature, the inside of the glass container was exposed to the atmosphere, and 10 g of THF was added to the obtained solution. Then, the solution containing THF was dropped into 100 g of MeOH as a solvent to precipitate a polymer. Thereafter, the solution containing the precipitated polymer was filtered using a Kiriyama funnel to obtain a white coagulate (copolymer A1).
  • copolymer A1 was composed of ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2 , 10 mol% of 2,2-trifluoroethyl units, 40 mol% of ⁇ -chloroacrylic acid 2,2,3,3,4,4,4-heptafluorobutyl units, and 50 mol% of ⁇ -methylstyrene units. It was a polymer. Thereafter, the number average molecular weight, weight average molecular weight, molecular weight distribution, and surface free energy of the obtained copolymer A1 were measured. The results are shown in Table 1.
  • Copolymer A1 prepared as described above was dissolved in isoamyl acetate as a solvent to prepare a positive resist composition having a concentration of 2% by mass.
  • the ⁇ value, Eth, pattern collapse resistance, and resist residue of the obtained positive resist composition were measured or evaluated. The results are shown in Table 2.
  • Copolymer A18 was prepared in the same manner as in Example 1, except that copolymer A18 was prepared using monomer composition A18 containing 0.1980 g of azobisisobutyronitrile and 8.9801 g of cyclopentanone as a solvent. Various operations, measurements, and evaluations were performed. The results are shown in Tables 1 and 2.
  • the inside of the system was heated to 60° C., and reaction was carried out for 8 hours to obtain a reaction solution in which the polymer was suspended. Thereafter, the polymer in the reaction solution was collected by filtration. Next, the polymer recovered by filtration was dissolved in 10 g of THF, and the resulting solution was dropped into 100 g of a mixed solvent of THF and MeOH (THF:MeOH (mass ratio) 33:67) to form a white solid. was precipitated. This coagulated material was collected again by filtration, the polymer collected by filtration was dissolved in 10 g of THF, and the resulting solution was dissolved in 100 g of a mixed solvent of THF and MeOH (THF:MeOH (mass ratio) 33:67).
  • copolymer B1 was composed of ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2 , 55 mol% of 2,2-trifluoroethyl units and 45 mol% of ⁇ -methylstyrene units. Thereafter, the number average molecular weight, weight average molecular weight, molecular weight distribution, and surface free energy of the obtained copolymer B1 were measured. The results are shown in Table 1.
  • Example 15 ⁇ Preparation of positive resist composition> Copolymer A1 prepared as above and copolymer B1 prepared as above were mixed at a mass ratio of copolymer A1 and copolymer B1 of 5:95 (copolymer A:copolymer B1). Polymer B) was dissolved in isoamyl acetate as a solvent to prepare a positive resist composition having a concentration of 2% by mass. The ⁇ value, Eth, pattern collapse resistance, and resist residue of the obtained positive resist composition were measured or evaluated. The results are shown in Table 3.
  • Example 16 In the preparation of a positive resist composition, the same procedure as in Example 15 was carried out except that the mass ratio of copolymer A1 and copolymer B1 was changed to 10:90 (copolymer A: copolymer B). Operations, measurements and evaluations were performed. The results are shown in Table 3.
  • Example 17 In the preparation of a positive resist composition, the same procedure as in Example 15 was carried out except that the mass ratio of copolymer A1 and copolymer B1 was changed to 20:80 (copolymer A: copolymer B). Operations, measurements and evaluations were performed. The results are shown in Table 3.
  • Example 18 In the preparation of a positive resist composition, the same procedure as in Example 15 was carried out except that the mass ratio of copolymer A1 and copolymer B1 was changed to 30:70 (copolymer A: copolymer B). Operations, measurements and evaluations were performed. The results are shown in Table 3.
  • Example 19 In preparing a positive resist composition, various operations, measurements, and evaluations were performed in the same manner as in Example 17, except that copolymer A2 was used instead of copolymer A1. The results are shown in Table 3.
  • Example 20 In preparing a positive resist composition, various operations, measurements, and evaluations were performed in the same manner as in Example 17, except that copolymer A5 was used instead of copolymer A1. The results are shown in Table 3.
  • Example 21 In preparing a positive resist composition, various operations, measurements, and evaluations were performed in the same manner as in Example 17, except that copolymer A10 was used instead of copolymer A1. The results are shown in Table 3.
  • Example 22 In preparing a positive resist composition, various operations, measurements, and evaluations were performed in the same manner as in Example 17, except that copolymer A11 was used instead of copolymer A1. The results are shown in Table 3.
  • Example 23 In preparing a positive resist composition, various operations, measurements, and evaluations were performed in the same manner as in Example 17, except that copolymer A13 was used instead of copolymer A1. The results are shown in Table 3.
  • Example 24 In preparing a positive resist composition, various operations, measurements, and evaluations were performed in the same manner as in Example 17, except that copolymer A14 was used instead of copolymer A1. The results are shown in Table 3.
  • Example 25 In preparing a positive resist composition, various operations, measurements, and evaluations were performed in the same manner as in Example 17, except that copolymer B2 was used instead of copolymer B1. The results are shown in Table 3.
  • Solution refers to solution polymerization
  • Bok refers to bulk polymerization
  • Supension refers to suspension polymerization
  • ACAFPh indicates ⁇ -chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl
  • ACAHFPh indicates ⁇ -chloroacrylate-1-phenyl-2,2,2-trifluoroethyl
  • ACANFP indicates 2,2,3,3,4,4,5,5,5-nonafluoropentyl ⁇ -chloroacrylate
  • ACAHFB indicates 2,2,3,3,4,4,4-heptafluorobutyl ⁇ -chloroacrylate
  • ACAPFP indicates 2,2,3,3,3-pentafluoropropyl ⁇ -chloroacrylate
  • ACATFE indicates 2,2,2-trifluoroethyl ⁇ -chloroacrylate
  • IPA refers to isopropyl alcohol.
  • the present invention it is possible to provide a copolymer that can improve the pattern collapse resistance while ensuring the clarity of the resist pattern. Further, according to the present invention, it is possible to provide a copolymer mixture that can improve the pattern collapse resistance while ensuring the clarity of the resist pattern. Further, according to the present invention, it is possible to provide a positive resist composition that can form a resist pattern with high pattern collapse resistance while ensuring clarity.

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Abstract

Le but de la présente invention est de fournir un copolymère capable d'augmenter la résistance à l'affaissement du motif tout en maintenant la clarté d'un motif de réserve. La présente invention concerne un copolymère ayant une unité monomère (I) représentée par la formule (I), une unité monomère (II) représentée par la formule (II) différente de l'unité monomère (I), et une unité monomère (III) représentée par la formule (III). En outre, dans les formules, L1, Ar1, X1, R1, X2, R2, R3, et R4 sont des groupes prédéterminés, p et q sont des nombres entiers entre 0 et 5 inclus, et p + q = 5.
PCT/JP2023/017091 2022-05-27 2023-05-01 Copolymère, mélange de copolymères et composition de réserve positive WO2023228692A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018123667A1 (fr) * 2016-12-27 2018-07-05 日本ゼオン株式会社 Polymère, composition de réserve positive et procédé de formation de motif de réserve
JP2018106066A (ja) * 2016-12-27 2018-07-05 日本ゼオン株式会社 レジストパターン形成方法
JP2018154754A (ja) * 2017-03-17 2018-10-04 日本ゼオン株式会社 共重合体およびポジ型レジスト組成物

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018123667A1 (fr) * 2016-12-27 2018-07-05 日本ゼオン株式会社 Polymère, composition de réserve positive et procédé de formation de motif de réserve
JP2018106066A (ja) * 2016-12-27 2018-07-05 日本ゼオン株式会社 レジストパターン形成方法
JP2018154754A (ja) * 2017-03-17 2018-10-04 日本ゼオン株式会社 共重合体およびポジ型レジスト組成物

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