JP2018044034A - Fluorine-containing monomer and fluorine-containing polymer thereof, resist prepared therewith and pattern forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorine-containing polymer as a component of resist for forming a fine resist pattern with less roughness.SOLUTION: A fluorine-containing polymer contains a repeating unit represented by formula (1) (Ris H or a protective group; A is a group containing an adamantane ring, optionally substituted with a hydroxy group or a thiol group).SELECTED DRAWING: None

Description

  The present invention relates to a fluorine-containing monomer, a fluorine-containing polymer thereof, a resist using the same, and a pattern forming method thereof.

  The progress of semiconductor manufacturing technology is remarkable, and for example, the number of elements integrated in a microprocessor is increasing. The increase in the number of elements is achieved by miniaturizing the line width of the electronic circuit pattern.

  In order to obtain a finer electronic circuit pattern, it is preferable to reduce the roughness of a resist pattern formed by photolithography (hereinafter simply referred to as lithography). Roughness includes line edge roughness (hereinafter sometimes referred to as LER), which is a phenomenon in which the edge of a pattern shifts from a straight line to unevenness, and line width roughness (Line, which is a phenomenon in which the line width of a resist shifts unevenly. Width Roughness). As described in Non-Patent Document 1, the smaller the roughness, the more precise the pattern, and the fine rectangular structure line and space can be obtained.

  In order to obtain a finer electronic circuit pattern, it is preferable that the light for exposing the resist film has a shorter wavelength in lithography. Shortening of wavelengths is progressing from visible light to ultraviolet light and further to extreme ultraviolet light (EUV).

  In ultraviolet light, a finer resist pattern can be obtained by using an argon fluoride excimer laser having a wavelength of 193 nm than using a krypton fluoride excimer laser having an oscillation wavelength of 248 nm for lithography. Specifically, in lithography using an argon fluoride excimer laser, pattern fine processing is usually performed based on a design rule having a line width of 0.13 μm or less.

  However, as a resist component in lithography using a krypton fluoride excimer laser, a novolak resin or polyvinylphenol resin that is usually used absorbs ultraviolet light with a wavelength of 193 nm, so that it can be diverted for an argon fluoride excimer laser as it is. Have difficulty.

  Therefore, in Patent Documents 1 to 4, an aliphatic resin that does not absorb ultraviolet light having a wavelength of 193 nm is selected as a resist resin suitable for an argon fluoride excimer laser, and further, resistance to etching after exposure is ensured. An acrylic resin or a cycloolefin resin in which the cyclic structure is introduced is disclosed.

  The acrylic resin can select various monomers having various side chains as a raw material, and has an advantage that the degree of freedom in molecular design when used as a resin is large.

  Usually, a carboxyl group is introduced into the structure as an alkali-soluble group for dissolving in an alkali developer in an acrylic resin for resist. However, when a carboxyl group is selected as the alkali-soluble group for the resist resin, its acidity is higher than that of the phenolic hydroxyl group possessed by the novolak resin and the polyvinylphenol-based resin, so it is difficult to control the dissolution rate in the alkali developer. There is a problem that the roughness of the pattern increases due to the swelling of the alkaline developer into the resist film.

Therefore, in order to suppress swelling of the alkaline developer into the resist film, Patent Documents 5 to 8 disclose that a polymer compound obtained by polymerizing a fluorinated alcohol monomer is used as a resist component. In particular, the resist containing the polymer compound disclosed in Patent Documents 6 to 8 is water repellent because the polymer compound contains a hexafluoroisopropanol group (—C (CF ₃ ) ₂ OH) in its structure, and the resist film It is described that a high-resolution pattern is obtained with little swelling of the alkaline developer to the substrate, and is suitable for lithography using a short wavelength light source for the purpose of fine processing.

  Patent Document 9 discloses a resist material having an acid desorption function as well as high transparency, substrate adhesion, and alkali development characteristics by using an acrylic resin having a hexafluoroisopropanol group directly bonded to the main chain as a base polymer. Has been. Specifically, a polymer compound containing a repeating unit represented by (1C) is described as the base polymer.

(In the formula, R has a hydrogen atom, an acid labile group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a fluorinated alkyl group, an acyl group, or a fluorinated alkyl moiety. Represents a group selected from an acyl group, R ¹ and R ² are a hydrogen atom or a fluorine atom, and R ⁵ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms or a fluorinated alkyl group; Represents.)

R ⁵ is methyl group, ethyl group, propyl group, isopropyl group, n-propyl group, sec-butyl group, tert-butyl group, cyclopentyl group, cyclohexyl group, 2-ethylhexyl group, n-octyl. Group, phenyl group, tricyclo [5,2,1,0] decylmethyl group, tricyclo [5,2,1,0] decanyl group, adamantyl group, norbornyl group, methylnorbornyl group, isobornyl group are exemplified. .

  In Examples, the following monomers are described and used as polymerizable monomers having acid-decomposable repeating units.

JP-A-9-73173 Japanese Patent Laid-Open No. 10-282671 Japanese Patent Laid-Open No. 9-230595 JP-A-9-325498 Japanese Patent Laid-Open No. 2002-072484 Japanese Patent Laid-Open No. 2004-083900 JP 2007-204385 A JP 2005-316352 A JP 2002-155112 A

L.H.A.Leunissen, et.al., Proc.DPS2004, 1-01

  An object of the present invention is to provide a resist that can form a fine resist pattern with less roughness. It is another object of the present invention to provide a fluorine-containing polymer as the resist component, a fluorine-containing monomer for obtaining the fluorine-containing polymer, and a pattern forming method using a resist using the fluorine-containing polymer.

  In order to solve the above-mentioned problems, the present inventors reacted acrylic acid having a hexafluoroisopropanol group bonded to the α-position with various adamantanols to produce a plurality of polymerizable adamantyl compounds as fluorine-containing monomers. An ester compound was synthesized.

The reason why the present inventors selected acrylic acid having a hexafluoroisopropanol group bonded to the α-position is that the hexafluoroisopropanol group (—C (CF ₃ ) ₂ OH) has 6 fluorine atoms and is polar. This is because it contains a hydroxyl group as a group and acts as an acidic group when used in a resist and exhibits solubility in an alkaline developer. The reason for selecting adamantanol is that the adamantyl group is a group having a strong and highly symmetric carbon skeleton, and when it is contained in a fluoropolymer as a resist component, it swells in the developer and changes its shape. This is because a resist pattern that is rigid and has little roughness is provided.

  Subsequently, these fluorine-containing monomers were copolymerized to obtain a fluorine-containing polymer, and the performance as a resist was evaluated. As a result, it has been found that a resist containing as a component a fluoropolymer having an adamantane skeleton having no linear or branched alkyl chain as a substituent gives a fine resist pattern with less roughness.

  The resist of the present invention was obtained by copolymerizing a polymerizable adamantyl ester compound having an adamantane skeleton having a linear and branched alkyl chain as a substituent and a polymerizable adamantyl ester compound containing an acid-decomposable group. Compared to a resist containing a fluorine-containing polymer as a component, a fine resist pattern having excellent resolution and less roughness is provided.

The present invention includes the following inventions 1 to 9.
[Invention 1]
A fluorine-containing polymer comprising a repeating unit represented by the formula (1).

(In the formula, R ¹ is a hydrogen atom or a protecting group. A is a group of any one of the following formulas (2A) to (2C) and (3A) to (3C)).

(Wherein R ² and R ³ are each independently a hydrogen atom, a hydroxyl group or a thiol group.)

(In the formula, R ⁴ and R ⁵ are each independently a hydrogen atom, a hydroxyl group or a thiol group, and R ⁶ is an oxygen atom or a sulfur atom.)

[Invention 2]
The fluorine-containing polymer of the invention 1, wherein A is a group represented by the formulas (2A) to (2C), and R ² and R ³ are hydrogen atoms.

[Invention 3]
Furthermore, the fluoropolymer of the invention 1 or the invention 2 containing a repeating unit other than the repeating unit represented by the formula (1).

[Invention 4] A resist comprising the fluoropolymers of Inventions 1 to 3.

[Invention 5] The resist according to Invention 4, further comprising an acid generator, a basic compound or an organic solvent.

[Invention 6] The resist according to Invention 5, wherein the organic solvent is an alcohol solvent having 5 to 20 carbon atoms.

[Invention 7] A step of applying a resist of Inventions 4-6 on a substrate to form a resist film;
Irradiating the resist film with a high energy ray having a wavelength of 300 nm or less via a photomask, and transferring the pattern of the photomask to the resist film;
Including a step of obtaining a resist pattern to be developed using a developer.
A method for forming a resist pattern.

[Invention 8]
A fluorine-containing polymerizable monomer represented by the formula (4).

(In the formula, R ¹ is a hydrogen atom or a protecting group. A is a group of any one of the following formulas (2A) to (2C) and (3A) to (3C)).

(Wherein R ² and R ³ are each independently a hydrogen atom, a hydroxyl group or a thiol group.)

(In the formula, R ⁴ and R ⁵ are each independently a hydrogen atom, a hydroxyl group or a thiol group, and R ⁶ is an oxygen atom or a sulfur atom.)

[Invention 9]
The fluorine-containing monomer according to claim 8, wherein A is a group represented by formulas (2A) to (2C), and R ² and R ³ are hydrogen.

  In addition, the resist of the present invention exhibits an appropriate water repellency in the state of the resist film before exposure in lithography, and when the resist pattern is obtained after exposure, it quickly dissolves in a developer, and the resulting resist pattern has a roughness. It provides a good resist pattern.

  If a resist containing the fluoropolymer of the present invention as a component and a pattern forming method using the resist are used in lithography, a fine resist pattern with little roughness can be formed.

1. Fluorinated monomer represented by formula (4) Fluorinated monomer represented by formula (4) (hereinafter referred to as fluorine-containing monomer) for introducing the repeating unit (1) into the fluoropolymer (1). The monomer (4) may be referred to below.

(In the formula, R ¹ is a hydrogen atom or a protecting group. A is a group of any one of the following formulas (2A) to (2C) and (3A) to (3C)).

(Wherein R ² and R ³ are each independently a hydrogen atom, a hydroxyl group or a thiol group.)

(In the formula, R ⁴ and R ⁵ are each independently a hydrogen atom, a hydroxyl group or a thiol group, and R ⁶ is an oxygen atom or a sulfur atom.)

[About R ¹ ]
In formula (1) and formula (4), R ¹ represents a hydrogen atom or a protecting group.

  In the present invention, the protecting group means an inert functional group in which a hydrogen atom of a highly reactive hydroxyl group is substituted.

In the present invention, the protective group is developed when a fluorine-containing polymer containing a repeating unit represented by the formula (1) (hereinafter sometimes referred to as a fluorine-containing polymer (1)) is used as a resist in lithography. When it is necessary to adjust the affinity for water or water, water repellency, or solubility in a solvent, it is introduced as a group that replaces the hydrogen atom of the hydroxyl group. If this is not necessary, it is easy to synthesize the fluorine-containing monomer (4) for introducing the repeating unit (1) into the fluorine-containing polymer (1). R ¹ preferably remains a hydrogen atom.

Examples of the protecting group include a hydrocarbon group, an alkoxycarbonyl group, an acetal group, and an acyl group. As the hydrocarbon group, a linear, branched or cyclic hydrocarbon group having 1 to 25 carbon atoms or an aromatic hydrocarbon group can be selected. Specifically, a methyl group, an ethyl group, a propyl group, Isopropyl group, cyclopropyl group, n-propyl group, iso-propyl group, sec-butyl group, tert-butyl group, n-pentyl group, cyclopentyl group, sec-pentyl group, neopentyl group, hexyl group, cyclohexyl group , Ethylhexyl group, norbornel group, adamantyl group, vinyl group, allyl group, butenyl group, pentenyl group, ethynyl group, phenyl group, benzyl group, or 4-methoxybenzyl group, and the hydrogen contained in these groups Some or all of the atoms may be substituted with fluorine atoms. Specific examples of the alkoxycarbonyl group include a tert-butoxycarbonyl group, a tert-amyloxycarbonyl group, a methoxycarbonyl group, an ethoxycarbonyl group, and an i-propoxycarbonyl group. Specific examples of the acetal group include a methoxymethyl group, a methoxyethoxymethyl group, an ethoxyethyl group, a butoxyethyl group, a cyclohexyloxyethyl group, a benzyloxyethyl group, a phenethyloxyethyl group, an ethoxypropyl group, a benzyloxypropyl group, Examples thereof include a chain ether group such as a phenethyloxypropyl group, an ethoxybutyl group or an ethoxyisobutyl group, or a cyclic ether group such as a tetraphytofuranyl group or a tetraphydropyranyl group. Specific examples of the acyl group include acetyl group, propionyl group, butyryl group, heptanoyl group, hexanoyl group, valeryl group, pivaloyl group, isovaleryl group, laurylyl group, myristoyl group, palmitoyl group, stearoyl group, oxalyl group, malonyl group Succinyl group, glutaryl group, adipoyl group, piperoyl group, suberoyl group, azelaoil group, sebacoyl group, acryloyl group, propioyl group, methacryloyl group, crotonoyl group, oleoyl group, maleoyl group, fumaroyl group, mesaconoyl group, canphoroyl group, Benzoyl group, phthaloyl group, isophthaloyl group, terephthaloyl group, naphthoyl group, toluoyl group, fidroatropoyl group, atropoyl group, cinnamoyl group, furoyl group, thenoyl group, nicotinoyl group, or Can be exemplified isonicotinoyl group, a part or all of the hydrogen atoms of these groups include may be substituted with a fluorine atom.
[When Group A is a Group Represented by Formulas (2A) to (2C)]

(Wherein R ² and R ³ are each independently a hydrogen atom, a hydroxyl group or a thiol group.)
Since it is easy to synthesize the fluorine-containing monomer (4) for introducing the repeating unit (1) to the fluorine-containing polymer (1), R ² and R ³ are each independently a hydrogen atom, a hydroxyl group or a thiol. It is preferably a group. When R ² or R ³ is a hydroxyl group or a thiol group, when the fluorine-containing monomer (4) is polymerized to obtain a fluorine-containing polymer (1), the solvent-soluble solution excellent in the fluorine-containing polymer (1) It is inferred that sex can be obtained. When a linear or branched alkyl group is selected as R ² or R ³ in formulas (2A) to (2C), it has a large number of freely rotatable carbon-carbon bonds, leading to a decrease in Tg and roughness. There are concerns that arise.

The fluorine-containing monomer (4) preferably used in the present invention in the case where R ¹ is a hydrogen atom and the group A is a group represented by the formulas (2A) to (2C) is specifically shown below. This is illustrated in

[When Group A is a Group Represented by Formulas (3A) to (3C)]

(In the formula, R ⁴ and R ⁵ are each independently a hydrogen atom, a hydroxyl group or a thiol group, and R ⁶ is an oxygen atom or a sulfur atom.)

Since it is easy to synthesize the fluorine-containing monomer (4) for introducing the repeating unit (1) into the fluorine-containing polymer (1), R ⁴ and R ⁵ are preferably a hydrogen atom or a hydroxyl group. . When R ⁴ or R ⁵ is a hydroxyl group or a thiol group, when the fluorine-containing monomer (4) is polymerized to obtain a fluorine-containing polymer (1), the solvent-soluble solution excellent in the fluorine-containing polymer (1) It is inferred that sex can be obtained.

R ⁶ is an oxygen atom or a sulfur atom, and together with the carbon to which R ⁶ is bonded, an oxygen atom represents a carbonyl group, and a sulfur atom represents a thiocarbonyl group.

Specific examples of the fluorine-containing monomer (4) preferred in the present invention in which R ¹ is a hydrogen atom and the group A is a group represented by the formulas (3A) to (3C) are shown below.

  The following monomers are particularly preferred fluorine-containing monomers (4) in the present invention because they are easily synthesized in these fluorine-containing monomers (4).

2. Synthesis of fluorinated monomer (4) An acrylic ester having a hexafluoroisopropanol group as a precursor of the fluorinated polymerizable monomer (4) is reacted with methyl acrylate or ethyl acrylate by a general reaction. It can be synthesized by reacting with hexafluoroacetone.

  This reaction may be performed by a known method, and 1,4-diazabicyclo [2.2.2] octane (DABCO) can be preferably used as a catalyst.

  The reaction for synthesizing the target fluorine-containing monomer (4) from an acrylic ester having a hexafluoroisopropanol group is not particularly limited, and a known esterification reaction may be used. Reaction of coupling an alcohol having a site containing an adamantyl skeleton to an acrylic acid ester having a hexafluoroisopropanol group, dehydrating an alcohol having a site containing an adamantyl skeleton after hydrolysis of the acrylic ester to acrylic acid A reaction for condensation, and further a reaction for coupling an alcohol having a site containing an adamantyl skeleton under basic conditions after converting acrylic acid to acrylic acid chloride can be selected.

3. Fluoropolymer (1)
By polymerizing the fluorine-containing monomer (4) of the present invention alone, or by polymerizing with a monomer having an acid labile group, a monomer having an adhesive group, or other monomers. A fluoropolymer (1) can be obtained.

  When the fluoropolymer (1) of the present invention is used as a resist component, in addition to the fluoromonomer (4), other monomers other than the fluoromonomer (4) can be developed in lithography. As described above, a monomer having a photofunctional acid-decomposable group, a monomer having an adhesive group for the purpose of obtaining adhesion to a substrate in lithography, and solvent solubility or developing solution dissolution when used as a resist film It is preferable to obtain a fluorinated polymer (1) by copolymerization using monomers for adjusting the properties, etching resistance of the film, mechanical strength and the like. A fluoropolymer (1) can be obtained by copolymerizing with another monomer for the purpose of adjustment.

  The monomer copolymerizable with the fluorine-containing monomer (4) that can be used in the present invention may be used alone or in combination of two or more when copolymerized with the fluorine-containing monomer (4). Also good.

3.1 Monomers having acid labile groups When the fluoropolymer (1) of the present invention is used as a resist component, positive photosensitivity is imparted by introducing acid labile groups into the chemical structure. In other words, the solubility in an alkaline developer after exposure to high energy rays such as ultraviolet rays, excimer lasers, X-rays or the like having a wavelength of 300 nm or less, or electron beams is developed.

  When an acid labile group is introduced into the fluoropolymer (1) of the present invention, a monomer having an acid labile group copolymerizable with the fluoromonomer (4) can be used.

  As the monomer having an acid labile group, the hexafluoroisopropanol group of the fluorine-containing polymerizable monomer (4) or the hydroxyl group bonded to the ring was protected with an acid labile protecting group as a protecting group. In general, a method of copolymerizing with a polymerizable monomer having an acid labile group other than the fluorine-containing polymerizable monomer (4) is preferably used.

  In the synthesis of the fluoropolymer (1) according to the present invention, the polymerizable monomer having an acid labile group copolymerizable with the fluorinated polymerizable monomer (4) has a photoacid generation. Any substance may be used as long as it is hydrolyzed by the acid generated from the agent.

  Examples of the polymerizable group of the polymerizable monomer having an acid labile group include an alkenyl group and a cycloalkenyl group. Specifically, a vinyl group, 1-methylvinyl group or 1-trifluoromethylvinyl group can be exemplified.

  The polymerizable monomer having an acid labile group used in the synthesis of the fluoropolymer (1) of the present invention includes the following formulas (5) to (5) linked to the polymerizable group in the structure. It is preferable to use a monomer having the group shown in 6).

In the formula, each of R ^{7 to} R ⁹ is independently a linear alkyl group having 1 to 25 carbon atoms, a branched alkyl group having 3 to 25 carbon atoms, or a cyclic alkyl group having 3 to 25 carbon atoms. A fluorine atom, an oxygen atom, a nitrogen atom, a sulfur atom, and a hydroxyl group may be contained, and two of R ^{7 to} R ⁹ may be bonded to form a ring.

In the formula, R ¹⁰ is a hydrogen atom, a linear alkyl group having 1 to 25 carbon atoms, a branched alkyl group having 3 to 25 carbon atoms, or a cyclic alkyl group having 3 to 25 carbon atoms, and a fluorine atom in the structure thereof, It may contain an oxygen atom, a nitrogen atom, a sulfur atom, or a hydroxyl group, and R ¹¹ is linear having 1 to 25 carbon atoms, branched having 3 to 25 carbon atoms, or cyclic having 3 to 25 carbon atoms. It is an alkyl group, and the structure may contain a fluorine atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a hydroxyl group.

  As the groups represented by the formulas (5) to (6) possessed by the polymerizable monomer having an acid labile group used in the synthesis of the fluoropolymer (1) of the present invention, specifically, The following groups can be exemplified.

3.2 Monomer having an adhesion group When the fluoropolymer (1) of the present invention is used as a resist component, by introducing an adhesion group into the chemical structure, preferable adhesion to the substrate in lithography is obtained. be able to. Examples of the adhesive group include a group containing a lactone structure.

  When introducing an adhesive group into the fluoropolymer (1) of the present invention, a single monomer containing a group having a monocyclic or polycyclic lactone structure copolymerizable with the fluoromonomer (4) The body can be used.

  Specifically, the monocyclic lactone structure is a group obtained by removing one hydrogen atom from γ-butyrolactone or mevalonic lactone, and the polycyclic lactone structure is one hydrogen atom from norbornane lactone. Except for, groups having a bond can be exemplified. A lactone structure is introduced into the fluoropolymer (1) of the present invention by copolymerizing an acrylate ester or a methacrylic ester containing a lactone structure. In this way, when the fluoropolymer (1) is used as a resist component for lithography, it is expected not only to improve the adhesion to the substrate but also to improve the affinity with the developer.

3.3 Other monomer When the fluoropolymer (1) of the present invention is used as a resist component, in addition to the fluoromonomer (4), a monomer having an acid-decomposable group, an adhesive group In addition to the monomer having the above, other monomers are used for the purpose of adjusting the solvent solubility or developer solubility in the resist film, the etching resistance of the film, the mechanical strength, and the like. A fluoropolymer (1) can be obtained.

  The other monomer copolymerizable with the fluorine-containing monomer (4) of the present invention is not limited as long as it is copolymerizable with the fluorine-containing monomer (4). , Methacrylates, fluorine-containing methacrylates, monomers having a hexafluoroisopropanol group, styrene compounds, fluorine-containing styrene compounds, vinyl ethers, allyl ethers, fluorine-containing vinyl ethers, fluorine-containing allyls Examples include ethers, olefins, fluorine-containing olefins, norbornene compounds, fluorine-containing norbornene compounds, vinyl esters, vinyl silanes, and other monomers having a polymerizable unsaturated bond.

  Specific examples of the other monomer having a polymerizable unsaturated bond include acrylic acid, methacrylic acid, acrylonitrile, maleic acid, fumaric acid, and maleic anhydride.

[Acrylic acid esters]
Specific examples of acrylic esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate. 2-hydroxyethyl acrylate or 2-hydroxypropyl acrylate, or acrylates having ethylene glycol, propylene glycol or tetramethylene glycol groups, or acrylamide, N-methylol acrylamide or diacetone acrylamide as an unsaturated amide, or tert-butyl acrylate , 3-oxocyclohexyl acrylate, adamantyl acrylate Examples include methyl adamantyl acrylate, ethyl adamantyl acrylate, hydroxy adamantyl acrylate, cyclohexyl acrylate or tricyclodecanyl acrylate, or acrylates having a ring structure such as a lactone ring or a norbornene ring, or these acrylates having a cyano group at the α-position be able to.

[Fluorine-containing acrylic esters]
Examples of the fluorinated acrylates include fluorinated acrylates in which the fluorinated organic group is bonded to the α-position of the acrylic moiety, or is bonded to the ester moiety. Both the α-position and the ester moiety may have a fluorine-containing organic group, or the α-position may have a cyano group and an ester moiety-containing fluorine-containing alkyl group.

  Examples of the fluorine-containing organic group bonded to the α-position of the fluorine-containing acrylic acid ester include a trifluoromethyl group, a trifluoroethyl group, and nonafluoro-n-butyl.

  The fluorine-containing organic group in the ester moiety of the fluorine-containing acrylic acid ester is a fluorine-containing alkyl group containing a perfluoro or hydrogen atom, or a hydrogen atom of a cyclic structure is a fluorine atom, a trifluoromethyl group, a hexafluoroisopropanol group, or the like. Examples thereof include a substituted fluorine-containing benzene ring, fluorine-containing cyclopentane ring, fluorine-containing cyclohexane ring, and fluorine-containing cycloheptane ring. Specific examples of such fluorine-containing acrylic esters include 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1,1,1,3,3, 3-hexafluoroisopropyl acrylate, heptafluoroisopropyl acrylate, 1,1-difidroheptafluoro-n-butyl acrylate, 1,1,5-trifidrooctafluoro-n-pentyl acrylate, 1,1,2,2 -Tetrafidrotridecafluoro-n-octyl acrylate, 1,1,2,2-tetrafidroheptadecafluoro-n-decyl acrylate, 6- [3,3,3-trifluoro-2-hydroxy 2- ( Trifluoromethyl) propyl] bicyclo [2.2.1] heptyl-2-yl acrylate, -[3,3,3-trifluoro-2-hydroxy 2- (trifluoromethyl) propyl] bicyclo [2.2.1] heptyl-2-yl 2- (trifluoromethyl) acrylate, 1,4-bis (1,1,1,3,3,3-hexafluoro-2-hydroxysopropyl) cyclohexyl acrylate, or 1,4-bis (1,1,1,3,3,3-hexafluoro-2-hydroxy Sopropyl) cyclohexyl 2-trifluoromethyl acrylate can be exemplified.

[Methacrylic acid esters]
As methacrylic acid esters, specifically, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate 2-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylate, or methacrylates having ethylene glycol, propylene glycol or tetramethylene glycol groups, or methacrylamide, N-methylol acrylamide, N-methylol methacrylamide or diacetone as unsaturated amides Acrylamide or tert-butyl methacrylate 3-oxo-cyclohexyl methacrylate, adamantyl methacrylate can be exemplified by methyl adamantyl methacrylate, ethyl adamantyl methacrylate, hydroxy adamantyl methacrylate, cyclohexyl methacrylate or tricyclodecanyl methacrylate or a methacrylate having a ring structure such as lactone ring or norbornene ring.

[Fluorine-containing methacrylates]
Examples of the fluorine-containing methacrylates include fluorine-containing methacrylates having a fluorine-containing organic group at the ester site.

  The fluorine-containing organic group in the ester moiety of the fluorine-containing methacrylate ester may be perfluorofluoro or a fluorine-containing alkyl group containing a hydrogen atom, or a hydrogen atom in a cyclic structure may be a fluorine atom, a trifluoromethyl group, a hexafluoroisopropanol group, or the like. And a fluorine-containing benzene ring, a fluorine-containing cyclopentane ring, a fluorine-containing cyclohexane ring or a fluorine-containing cycloheptane ring. Specific examples of such fluorinated acrylic esters include 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 1,1,1,3,3, 3-hexafluoroisopropyl methacrylate, heptafluoroisopropyl methacrylate, 1,1-dihydroheptafluoro-n-butyl methacrylate, 1,1,5-trihydrooctafluoro-n-pentyl methacrylate, 1,1,2,2-tetrahydro Tridecafluoro-n-octyl methacrylate, 1,1,2,2-tetrahydroheptadecafluoro-n-decyl methacrylate, perfluorocyclohexylmethyl acrylate, perfluorocyclohexylmethyl methacrylate, 6- [3,3,3-trifluoro -2 Hydroxy-2- (trifluoromethyl) propyl] bicyclo [2.2.1] heptyl-2-yl methacrylate, 1,4-bis (1,1,1,3,3,3-hexafluoro-2-hydroxy An example is isopropyl) cyclohexyl methacrylate.

[Monomer having a hexafluoroisopropanol group]
Specifically, the monomers shown below can be exemplified.

(R ⁷ represents a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group. The hexafluoroisopropanol group may be partially or entirely protected with a protecting group.)

[Styrene compounds, fluorine-containing styrene compounds]
Fluorinated styrene and hydroxystyrene. More specifically, styrene, pentafluorostyrene, trifluoromethylstyrene, bistrifluoromethylstyrene, a fluorine atom or a trifluoromethyl group substituted with a hydrogen atom of an aromatic ring structure. Styrene with styrene, hexafluoroisopropanol group or hexafluoroisopropanol group whose hydroxyl group is protected with a protecting group, substituted with hydrogen of aromatic ring, halogen atom, alkyl group or fluorine-containing alkyl group bonded to α-position Examples of these styrenes or perfluorovinyl group-containing styrenes can be given.

[Vinyl ethers, allyl ethers, fluorine-containing vinyl ethers, fluorine-containing allyl ethers]
As vinyl ether or allyl ether, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, t-butyl group, hydroxyethyl group or hydroxybutyl group Or alkyl vinyl ether or alkyl allyl ether. The vinyl ether having a hydroxyethyl group or a hydroxybutyl group may be a vinyl ether in which the hydroxy group is bonded to an acetyl group, a butyroyl group, or a propinoyl group to form an ester bond. It may be a cyclopentyl group, a cyclohexyl group, a norbornyl group, an aromatic ring, a cyclic vinyl ether having a hydrogen atom or a carbonyl bond in the cyclic structure, or a cyclic allyl ether. Examples of the fluorine-containing vinyl ether and fluorine-containing allyl ether include fluorine-containing vinyl ethers or fluorine-containing allyl ethers in which some or all of the hydrogen atoms of the vinyl ether or allyl ether are substituted with fluorine atoms.

[Olefins, fluorine-containing olefins]
Specific examples of olefins include ethylene, propylene, isobutene, cyclopentene, and cyclohexene. Specific examples of the fluorinated olefins include vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, xafluoroisobutene, 1-chloro-2,3,3. , 4, 4, 5, 5-heptafluorocyclopentene, octafluorocyclopentene or decafluorocyclohexene.

[Norbornene compound, fluorine-containing norbornene compound]
The norbornene compound and the fluorine-containing norbornene compound have a polymerizable group, and may have not only one norbornene skeleton but also a plurality of norbornene skeletons.

  Examples of the norbornene compound or the fluorine-containing norbornene compound include a norbornene compound produced by a Diels-Alder addition reaction between an unsaturated compound and a diene compound.

  Specific examples of unsaturated compounds include fluorine-containing olefins, allyl alcohol, fluorine-containing allyl alcohol, homoallyl alcohol, fluorine-containing homoallyl alcohol, acrylic acid, α-fluoroacrylic acid, α-trifluoromethylacrylic acid, Methacrylic acid, acrylic acid ester, methacrylic acid ester, fluorine-containing acrylic acid ester or fluorine-containing methacrylate ester, 2- (benzoyloxy) pentafluoropropane, 2- (methoxyethoxymethyloxy) pentafluoropropene, 2- (tetra Hydroxypyranyloxy) pentafluoropropene, 2- (benzoyloxy) trifluoroethylene, or 2- (methoxymethyloxy) trifluoroethylene can be exemplified. Examples of the diene compound include cyclopentadiene and cyclohexadiene.

  Examples of such norbornene compounds include 3- (5-bicyclo [2.2.1] hepten-2-yl) -1,1,1-trifluoro-2- (trifluoromethyl) -2-propanol. be able to.

3.4 Content ratio of each repeating unit in the fluoropolymer (1) The content of the repeating unit represented by the formula (1) derived from the fluoromonomer (4) with respect to the total amount of the fluoropolymer (1). The ratio is preferably 1 mol% or more and 100 mol% or less, more preferably 5 mol% or more and 90 mol%. The content ratio of the repeating unit derived from the monomer having an acid labile group is preferably 1 mol% or more and 99 mol% or less, more preferably 5 mol% or more and 80 mol%, particularly preferably 10 mol% or more and 60 mol% or less. is there. Furthermore, other polymerizable monomers including a monomer having an adhesive group can also be used, and the repeating unit derived from the other polymerizable monomer with respect to the total amount of the fluoropolymer (1). The content ratio is preferably 1 mol% or more and 80 mol% or less, more preferably 5 mol% or more and 50 mol% or less.

  When the content of the repeating unit derived from the fluorine-containing monomer (4) in the fluorine-containing polymer (1) is less than 1 mol%, it is a feature that the fluorine-containing polymer (1) is used as a resist component. A clear effect of obtaining a fine resist pattern with little roughness cannot be expected. When the content of the repeating unit having an acid labile group in the fluoropolymer (1) is less than 1 mol%, the resist film is exposed to an alkali developer in an irradiated area and an unirradiated area in development after exposure. Since the change in solubility is too small, desired contrast and roughness cannot be expected in the resulting resist pattern.

  Repeating units derived from other monomers are used to improve the solubility of the fluoropolymer in organic solvents, the etching resistance of the film, the mechanical strength, etc., but the effect is manifested at less than 1 mol%. Without exceeding 80 mol%, the content of the repeating unit represented by the formula (1) decreases, and the above effect cannot be expected.

3.5 Molecular Weight of Fluoropolymer (1) The number average molecular weight of the fluoropolymer (1) of the present invention is preferably 1,000 or more and 100,000 or less, more preferably 3,000 or more, 50 , 000 or less. The molecular weight dispersion is preferably 1 or more and 4 or less, more preferably 1 or more and 2.5 or less.

  When the molecular weight is less than 1000, the change in solubility in the alkaline developer in the irradiated area and the unirradiated area is too small in the development after exposure when the resist film is formed, and the obtained resist pattern has desired contrast and roughness. I can't expect it. When it exceeds 100,000, it becomes difficult to dissolve in a solvent when forming a resist.

4). Synthesis of fluorinated polymer (1) The means for synthesizing the fluorinated polymer (1) of the present invention can be selected from generally used polymerization methods, and radical polymerization and ionic polymerization are preferred. Coordinating anionic polymerization, living anionic polymerization, cationic polymerization, and the like can also be selected. The reactor used for the polymerization reaction is not particularly limited. In the polymerization reaction, a polymerization solvent may be used.

  Radical polymerization is carried out in the presence of a radical polymerization initiator or a radical initiator by a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization, and is either batch-wise, semi-continuous or continuous. This can be done by operation.

[Radical polymerization initiator]
Examples of the radical polymerization initiator include azo compounds, peroxide compounds, and redox compounds. Specifically, azobisisobutyronitrile, t-butyl peroxypivalate, di-t-butyl peroxide, i-butyryl peroxide, lauroyl peroxide, succinic acid peroxide, dicinnamyl peroxide, di-n Examples include -propyl peroxydicarbonate, t-butyl peroxyallyl monocarbonate, benzoyl peroxide, hydrogen peroxide, or ammonium persulfate.

[Polymerization solvent]
The polymerization solvent is preferably one that does not inhibit radical polymerization, and examples thereof include ester solvents, ketone solvents, hydrocarbon solvents, and alcohol solvents. In addition, water, ether-based, cyclic ether-based, chlorofluorocarbon-based, or aromatic solvents may be used.

  Specifically, ethyl acetate or n-butyl acetate as an ester solvent, acetone or methyl isobutyl ketone as a ketone solvent, toluene or cyclohexane as a hydrocarbon solvent, or methanol, isopropyl alcohol or alcohol as an alcohol solvent An example is ethylene glycol monomethyl ether.

  These polymerization solvents may be used alone or in combination of two or more. Moreover, you may use together molecular weight regulators, such as a mercaptan.

[Polymerization conditions]
The reaction temperature of the co-polymerization reaction varies depending on the type of radical polymerization initiator or radical polymerization initiator, and preferably initiates radical polymerization so that it is 20 ° C. or higher and 200 ° C. or lower, more preferably 30 ° C. or higher and 140 ° C. or lower. It is preferable to select an agent or radical polymerization initiation source.

  As a method of removing the polymerization solvent such as an organic solvent or water from the solution or dispersion liquid contained in the fluoropolymer (1) after polymerization, a known method can be used. And heating distillation under reduced pressure.

  When the fluoropolymer (1) of the present invention is used as a resist component, the solubility of the fluoropolymer (1) in the developer varies depending on the molecular weight of the fluoropolymer (1). Patterning conditions can vary. When the fluorine-containing polymer (1) has a high molecular weight, the dissolution rate in the developer tends to be low, and when the molecular weight is low, the dissolution rate tends to increase. The molecular weight of the fluoropolymer (1) can be controlled by adjusting the polymerization conditions.

5. Resist The fluoropolymer (1) of the present invention is particularly suitably used as a component of a photosensitized positive resist. The present invention provides a resist, particularly a positive resist material, containing the fluoropolymer (1).

  The resist preferably contains (A) the fluoropolymer (1) of the present invention, (B) a photoacid generator, (C) a basic compound, and (D) a solvent as its components. If necessary, (E) a surfactant may be added.

(B) Photoacid generator There is no restriction | limiting in particular in the photoacid generator used for the resist material of this invention, It selects and uses from the thing used as an acid generator of a chemically amplified resist. And can include onium sulfonates or sulfonate esters. Specifically, iodonium sulfonate, sulfonium sulfonate, N-imido sulfonate, N-oxime sulfonate, o-nitrobenzyl sulfonate, or pyrogallol trismethane sulfonate can be exemplified.

  Acids generated from these photoacid generators upon exposure in lithography are alkane sulfonic acids, aryl sulfonic acids, or partially or fully fluorinated aryl sulfonic acids or alkane sulfonic acids. Of these photoacid generators, photoacid generators that generate partially or fully fluorinated alkanesulfonic acids are preferred. Specifically, triphenylsulfonium trifluoromethanesulfonate or triphenylsulfonium perfluoro-n-octanesulfonate can be exemplified.

(C) Basic compound A basic compound can be mix | blended with the resist containing the fluoropolymer (1) of this invention. The basic compound has a function of slowing the diffusion rate when the acid generated from the photoacid generator diffuses into the resist film. When compounding basic compounds, the acid diffusion distance is adjusted to improve the shape of the resist pattern, and the stability to give a resist pattern with the desired accuracy is improved even when the exposure time is long after the resist film is formed. Expected to be effective.

  Examples of such basic compounds include aliphatic amines, aromatic amines, heterocyclic amines, and aliphatic polycyclic amines. Among these amines, a secondary or tertiary aliphatic amine or an alkyl alcohol amine is preferable. Specifically, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecanylamine, tridodecylamine, dimethylamine, diethylamine, di Propylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecanylamine, didodecylamine, dicyclohexylamine, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octyl Amine, nonylamine, decanylamine, dodecylamine, diethanolamine, triethanolamine, diisopropanol Min, triisopropanolamine, di-octanol amine, tri octanol amine, aniline, pyridine, picoline, lutidine, bipyridine, pyrrole, piperidine, can be exemplified piperazine, indole or hexamethylenetetramine. These basic compounds may be used alone or in combination of two or more.

  The compounding quantity of the basic compound in a resist is 0.001-2 mass parts with respect to 100 mass parts of fluoropolymer (1), More preferably, it is 0.01-1 mass part with respect to 100 mass parts of polymers. is there. When the blending amount is less than 0.001 part by mass, the effect as an additive cannot be obtained sufficiently, and when it exceeds 2 parts by mass, resolution and sensitivity may decrease.

(D) Solvent In addition to (A) the fluoropolymer (1) of the present invention, (B) a photoacid generator, (C) a basic compound, the resist containing the fluoropolymer (1) of the present invention includes (D) A solvent is blended. The solvent may be any solvent as long as (A) the fluoropolymer (1) of the present invention, (B) the photoacid generator, and (C) the resist component containing the basic compound can be dissolved into a uniform solution. Can be selected and used. Two or more kinds of solvents may be mixed and used.

  Examples of such solvents include ketones, alcohols, polyhydric alcohols, esters, aromatic solvents, ethers, fluorine-based solvents, and terpene-based petroleum naphtha solvents that are weak solvents with a high boiling point for the purpose of improving coatability. And paraffinic solvents.

  Specifically, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl isobutyl ketone methyl isopentyl ketone or 2-heptanone as ketones, isopropanol, butanol, isobutanol, n-pentanol, isopentanol as alcohols Tert-pentanol, 4-methyl-2-pentanol, 3-methyl-3-pentanol, 2,3-dimethyl-2-pentanol, n-hexisanol, n-heptanol, 2-heptanol, n-octanol N-decanol, s-amyl alcohol, t-amyl alcohol, isoamyl alcohol, 2-ethyl-1-butanol, lauryl alcohol, hexyl decanol or oleyl alcohol, ethylene as a polyhydric alcohol Recall, diethylene glycol, propylene glycol, dipropylene glycol, ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol Monobutyl ether, propylene glycol monomethyl ether acetate (PGMEA) or propylene glycol monomethyl ether (PGME), and derivatives of these polyhydric alcohols, methyl lactate as esters, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, Methyl pyruvate, ethyl pyruvate, Examples include methyl toxipropionate or ethyl ethoxypropionate, toluene or xylene as an aromatic solvent, diethyl ether, dioxane, anisole or diisopropyl ether as ethers, or hexafluoroisopropyl alcohol as a fluorine solvent. .

  Among these solvents, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and ethyl lactate (EL) are preferable as the resist containing the fluoropolymer (1) of the present invention.

  The amount of the solvent to be blended in the resist containing the fluoropolymer (1) of the present invention is not particularly limited, but the solid content concentration in the resist is preferably 3% by mass or more and 25% by mass or less, more preferably. Is 5 mass% or more and 15 mass% or less. By adjusting the solid content concentration of the resist, it is possible to adjust the film thickness of the formed resin film.

  In addition, the fluoropolymer (1) of the present invention is excellent in solubility in a wide range of solvents, and it should be noted that among the above alcohol solvents, it can be dissolved in an alcohol solvent having 5 to 20 carbon atoms. It is. Specific examples of such alcohols include n-pentanol, isopentanol, tert-pentanol, 4-methyl-2-pentanol, 3-methyl-3-pentanol, and 2,3-dimethyl-2-pen. Tanol, n-hexisanol, n-heptanol, 2-heptanol, n-octanol, n-decanol, s-amyl alcohol, t-amyl alcohol, isoamyl alcohol, 2-ethyl-1-butanol, lauryl alcohol, hexyl decanol or oleyl alcohol Can be illustrated.

(E) Surfactant In the resist containing the fluoropolymer (1) of the present invention, a surfactant may be added if necessary. Examples of the surfactant include a fluorine-based surfactant, a silicon-based surfactant, and a surfactant having both a fluorine atom and a silicon atom, and can contain two or more kinds.

6). Pattern Forming Method Lithographic pattern formation using a resist containing the fluoropolymer (1) of the present invention comprises (A) a step of applying a resist on a substrate to form a resist film, and (B) heating the resist film. And (C) developing the exposed resist film with an alkali developer and exposing the resist film to the substrate with a high energy ray such as an electromagnetic wave having a wavelength of 300 nm or less through a patterned photomask. The process includes a process of obtaining a resist pattern to which a photomask pattern is transferred, and can be performed by employing a known lithography technique.

Specifically, a resist containing the fluoropolymer (1) of the present invention is applied to a silicon wafer as a substrate by spin coating, and the silicon wafer is heated to 60 ° C. or higher and 200 ° C. or lower on a hot plate. Pre-bake for 2 seconds or longer and 10 minutes or shorter, preferably 80 ° C. or higher, 150 ° C. or lower, 30 seconds or longer and 2 minutes or shorter, to form a resist film on the substrate. Next, the patterned photomask is set in an exposure apparatus, and high energy rays such as ultraviolet rays, excimer laser, and X-rays or electron beams are applied at an exposure amount of 1 mJ / cm ² or more, 200 mJ / cm ² or less, preferably 10 mJ / After irradiating the resist film through a photomask so as to be cm ² or more and 100 mJ / cm ² or less, it is 60 ° C. or more, 150 ° C. or less, 10 seconds or more, 5 minutes or less, preferably 80 ° C. or more on a hot plate , 130 ° C. or lower, 30 seconds or longer, 3 minutes or shorter, and post-exposure baking (PEB). Furthermore, using a developer with an aqueous solution of tetramethylammonium hydroxide (TMAH) having a concentration of 0.1% by mass or more and 5% by mass or less, preferably 2% by mass or more and 3% by mass or less, 10 seconds or more and 3 minutes or less. The target resist pattern can be obtained by bringing the resist film into contact with an existing method such as a dip method, a paddle method, or a spray method for 30 seconds or more and 2 minutes or less and developing. In addition, what is necessary is just to perform the said post-exposure baking (PEB) as needed.

  The substrate can be a metal or glass substrate in addition to a silicon wafer. An organic or inorganic film may be provided on the substrate. For example, there may be an antireflection film, a lower layer of a multilayer resist, or a resist pattern may be formed.

  In the lithography of the resist containing the fluoropolymer (1) of the present invention, the wavelength of the electromagnetic wave used for exposure is not limited, but UV light (wavelength 248 nm) by KrF excimer laser, UV light (wavelength 193 nm) by ArF excimer laser. ), Extreme ultraviolet lithography (EUV), and X-rays can be selected, and it is particularly preferably used for an ArF excimer laser.

  The resist containing the fluoropolymer (1) of the present invention has an appropriate water repellency with respect to water before exposure, exhibits rapid solubility in a developer after exposure, and has excellent resolution without roughness. Pattern formation is possible.

  A semiconductor device can be manufactured by the pattern formation method by lithography using the resist containing the fluoropolymer (1) of the present invention. Although it does not specifically limit as a device, The semiconductor device manufactured by microfabrication, such as CPU, SRAM, DRAM, etc. which are formed in a silicon wafer, a compound semiconductor substrate, an insulating substrate, etc. is mentioned.

  The resist containing the fluoropolymer (1) of the present invention can be made into a solution with an alcohol solvent having 5 to 20 carbon atoms that cannot dissolve a general resist material. Thereby, it can be used as an upper layer resist for a double patterning process. Moreover, the resist containing the fluoropolymer (1) of the present invention has high water resistance, and has an affinity for a developer while having appropriate water repellency.

  The resist containing the fluoropolymer (1) of the present invention has an appropriate water repellency with respect to water before exposure, and exhibits rapid solubility in a developer after exposure. It is presumed that a pattern with excellent resolution without roughness can be formed in immersion exposure in which the space between the lenses is filled with a medium having a higher refractive index than air such as water. In photolithography by immersion exposure, a topcoat film, which is a resist protective film, may or may not be used, but the resist containing the fluoropolymer (1) of the present invention has the composition and formulation. It is presumed that adjustment can also be applied to immersion exposure.

  Examples of the immersion exposure medium include, in addition to water, fluorine-based solvents, silicon-based solvents, hydrocarbon-based solvents, sulfur-containing solvents, and the like, and resists containing the fluorine-containing polymer (1) of the present invention are those. It may also be applicable to media.

  Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples.

1. Monomer Synthesis 1.1 Monomer-1 Synthesis <Precursor Compound-1 Synthesis>
As shown in the following formula, in a reactor equipped with a stirrer, methyl acrylate, 30.1 g (0.35 mol), and 1,4-diazabicyclo [2.2.2] octane (DABCO) as an organic alkali ) 1.96 g (0.0175 mol) was charged and the reactor was sealed. Next, the inside of the reactor was degassed with a vacuum pump, and then 69.7 g (0.42 mol) of 1,1,1,3,3,3-hexafluoroacetone was introduced while stirring the contents with a stirrer. . Next, the temperature inside the reactor was raised to 80 ° C., and then stirring was continued for 20 hours. After completion of the reaction, the contents were extracted and transferred to a separatory funnel, 30 ml of hydrochloric acid having a concentration of 3.5% by mass was added, and the mixture was washed twice with 30 ml of pure water. The organic layer was separated and distilled under reduced pressure under conditions of a pressure of 1.8 kPa and a temperature of 56 ° C. to 59 ° C., and (4,4,4-trifluoro-3-hydroxy-) as precursor compound-1 represented by the following formula: 75 g of methyl 2-methylene-3- (trifluoromethyl) butanoate was obtained with a yield of 85%.

The measurement data by a nuclear magnetic resonance spectrum (NMR) are shown.
¹ H-NMR (solvent: deuterated chloroform, reference material: TMS); δ (ppm) 3.88 (3H, s), 6.43 (1H, s (d, J = 2 Hz)), 6.87 (1H , S (d, J = 2Hz)), 7.88 (1H, s),
¹⁹ F-NMR (solvent: deuterated chloroform, reference material: C6D6); δ (ppm) -76.6 (6F, s)

<Synthesis of Precursor Compound-2>
Precursor compound-1, 70.6 g (0.28 mol) was placed in a reactor equipped with a stirrer, 196 g (0.70 mol) of an aqueous potassium hydroxide solution having a concentration of 20% by mass was added, and the inside of the reactor was 50 ° C. The mixture was warmed to 2 hours and stirred for 2 hours. Next, 71 g of hydrochloric acid having a concentration of 3.5% by mass was added and stirred. The contents were transferred to a separatory funnel, 150 ml of ethyl acetate was added, and the mixture was allowed to stand to separate the organic layer and washed twice with 70 ml of pure water. The resulting solution was concentrated and recrystallized. The crystals were filtered and dried to obtain 50 g of 4,4,4-trifluoro-3-hydroxy-2-methylene-3- (trifluoromethyl) butanoic acid as precursor compound-2 shown below. 75% was obtained.

The measurement data by a nuclear magnetic resonance spectrum (NMR) are shown.
¹ H-NMR (solvent: deuterated chloroform, reference material: TMS); δ (ppm) 6.62 (1 H, s (d, J = 2 Hz)), 7.11 (1 H, s (d, J = 2 Hz) ),
¹⁹ F-NMR (solvent: deuterated chloroform, reference material: C6D6); δ (ppm) -76.3 (6F, s)

<Synthesis of Monomer-1>
In a reactor, 1-adamantanol 48.1 g (0.316 mol), precursor compound-2, 82.7 g (0.35 mol), p-toluenesulfonic acid 6.01 g (0.036 mol), and methylcyclohexane 300 ml were added. Then, using a Dean-Stark apparatus, the mixture was refluxed at a temperature of 101 ° C. to perform a dehydration reaction. After completion of the dehydration reaction, sodium bicarbonate water having a concentration of% by mass was added and stirred. The reaction solution was transferred to a separatory funnel and allowed to stand to separate the organic layer, which was washed twice with pure water. The obtained reaction solution was concentrated and then crystallized in a mixed solvent having a mass ratio of acetone: water = 1: 3. The crystals were filtered and dried after that, yielding adamantyl 4,4,4-trifluoro-3-hydroxy-2-methylene-3- (trifluoromethyl) butanoate as monomer-1 shown below. Obtained at 75%.

The measurement data by a nuclear magnetic resonance spectrum (NMR) are shown.
¹ H-NMR (solvent: deuterated chloroform, reference material: TMS); δ (ppm) 1.55-1.75 (6H, m), 2.11-2.25 (9H, m), 6.31 ( 1H, s (d, J = 2Hz)), 6.74 (1H, s (d, J = 2Hz)), 8.17 (1H, s),
¹⁹ F-NMR (solvent: deuterated chloroform, reference material: C6D6); δ (ppm) -76.4 (6F, s)

1.2 Synthesis of Monomer-2 Other procedures were the same as those in the synthesis of Monomer-1 except that 1,3-adamantanediol was used instead of 1-adamantanol. As a monomer-2, 4,4,4-trifluoro-3-hydroxy-2-methylene-3- (trifluoromethyl) butanoic acid 3-hydroxy-1-adamantyl was synthesized.

1.3 Synthesis of Monomer-3 Other procedures were the same except that 4-oxo-adamantan-1-ol was used instead of 1-adamantanol in the synthesis of Monomer-1 described above. 4,4,4-trifluoro-3-hydroxy-2-methylene-3- (trifluoromethyl) butanoic acid-4-oxo-1-adamantyl as monomer-3 shown below was synthesized.

1.4 Synthesis of Monomer-4 Other procedures were the same except that 4-oxo-adamantan-1-ol was used instead of 1-adamantanol in the synthesis of Monomer-1 described above. 4,4,4-trifluoro-3-hydroxy-2-methylene-3- (trifluoromethyl) butanoic acid-2-adamantyl as monomer-4 shown below was synthesized.

2. Synthesis of Comparative Monomer 2.1 Synthesis of Comparative Monomer-1 In the synthesis of Monomer-1, the other procedures were the same except that Compound (A) was used instead of 1-adamantanol. Comparative monomer-1 shown below was synthesized.

2.2 Synthesis of Comparative Monomer-2 Other procedures were the same except that Compound (B) was used in place of 1-adamantanol in the synthesis of Monomer-1 described above. Monomer-2 was synthesized.

2.3 Synthesis of Comparative Monomer-3 In the synthesis of Monomer-1, the other procedures were the same except that hexafluoroisopropanol (HFIP) was used instead of 1-adamantanol. Comparative monomer-3 shown was synthesized.

2.4 Synthesis of Comparative Monomer-4 Other procedures were the same except that 4-ethyl-4-hydroxyadamantanol was used instead of 1-adamantanol in the synthesis of monomer-1 described above. 4,4,4-trifluoro-3-hydroxy-2-methylene-3- (trifluoromethyl) butanoic acid-4-ethyl-4-hydroxyadamanti- as comparative monomer-4 shown below 1-yl was synthesized.

2.5 Synthesis of Comparative Monomer-5 In the synthesis of Monomer-1, the other procedures were the same except that 1-ethyl-1-adamantanol was used instead of 1-adamantanol. 4,4,4-trifluoro-3-hydroxy-2-methylene-3- (trifluoromethyl) butanoic acid-1-ethyl-1-adamantyl as a comparative monomer-5 shown below was synthesized.

3. Synthesis of Polymer Comparative polymers were synthesized using Polymers 1 to 5 and Comparative Monomers 1 to 5 using the synthesized monomers 1-6.

[Analysis of polymer]
The composition of the repeating composition in the polymer was determined by measurement of 1H-NMR and 19F-NMR by measuring the nuclear magnetic resonance spectrum.

  The number average molecular weight Mn and the molecular weight dispersion (ratio Mw / Mn of the number average molecular weight Mn and the mass average molecular weight Mw) of the polymer were measured using a high-speed gel permeation chromatography apparatus (manufactured by Tosoh Corporation, model HLC-8320GPC). One ALPHA-M column and one ALPHA-2500 column manufactured by Co., Ltd. were connected in series and measured using tetrahydrofuran as a developing solvent. The detector used was a refractive index difference measurement detector.

3.1 Synthesis of Polymer-1 In a glass flask, 37.2 g of monomer-1 at room temperature (about 20 ° C.), 1-ethyl methacrylate giving an acid-dissociable repeating unit when used as a resist 9.1 g of -1-cyclopentane (hereinafter may be referred to as MA-ECp), 5-methacryloyloxy-2,6-norbornanecarbolactone (hereinafter referred to as MNLA) which gives an adhesive repeating unit 11.1 g of n) and 0.67 g of n-dodecyl mercaptan (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and 82.8 g of 2-butanone was added and dissolved. 1.72 g of 2,2′-azobis (isobutyronitrile) (hereinafter sometimes referred to as AIBN, manufactured by Wako Pure Chemical Industries, Ltd.) was added as a polymerization initiator, and the mixture was degassed while stirring. And the temperature was raised to 75 ° C., followed by reaction for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. The precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and the following polymer-1 containing a repeating unit derived from monomer 1, a repeating unit derived from MA-ECp, and a repeating unit derived from MNLA Was obtained as a white solid in a yield of 56%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is monomer-1 origin: MA-ECp origin: MNLA origin = 28: 35: 37.
The GPC measurement results are Mn = 8,500 and Mw / Mn = 2.1.

3.2 Synthesis of Polymer-2 1-Ethyl-1-adamantyl methacrylate giving 37.2 g of monomer-2 at room temperature as a resist in a glass flask, giving an acid dissociable repeating unit (Hereafter, it may be called MA-EAD) 12.4g, MNLA 11.1g, and n-dodecyl mercaptan 0.67g were prepared, and 2-butanone 82.8g was added and dissolved. After 1.7 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C., followed by reaction for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. This precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and polymer-2 containing the following repeating unit derived from monomer-1, repeating unit derived from MA-EAD, and repeating unit derived from MNLA Was obtained as a white solid in a yield of 52%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is monomer-1 origin: MA-EAD origin: MNLA origin = 27: 33: 40.
The measurement results of GPC are Mn = 9,400 and Mw / Mn = 2.2.

3.3 Synthesis of Polymer-3 In a glass flask, 38.8 g of monomer-2, 9.1 g of MA-ECp, 11.1 g of MNLA, and 0.67 g of n-dodecyl mercaptan at room temperature. Charge, 82.8 g of 2-butanone was added and dissolved. After 1.7 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C., followed by reaction for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. The precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and the following polymer containing a repeating unit derived from monomer-2, a repeating unit derived from MA-ECp and a repeating unit derived from MNLA— 3 was obtained as a white solid (Polymer-3) in 32.6 g with a yield of 55%. Obtained.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is monomer-2 origin: MA-ECp origin: MNLA origin = 28: 36: 36.
The GPC measurement results are Mn = 10,400 and Mw / Mn = 1.8.

3.4 Synthesis of Polymer-4 In a glass flask, 38.6 g of monomer-3, 9.1 g of MA-ECp, 11.1 g of MNLA and 0.67 g of n-dodecyl mercaptan at room temperature. Charge, 82.8 g of 2-butanone was added and dissolved. After 1.7 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C., followed by a reaction for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. The precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and the following polymer containing a repeating unit derived from monomer-3, a repeating unit derived from MA-ECp and a repeating unit derived from MNLA— 4 was obtained as a white solid in 30.0 g with a yield of 51%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is derived from monomer-3: derived from MA-ECp: derived from MNLA = 32: 33: 35.
The GPC measurement results are Mn = 8,400 and Mw / Mn = 2.3.

3.5 Synthesis of Polymer-5 In a glass flask, 37.2 g of monomer-4, 9.1 g of MA-ECp, 11.1 g of MNLA) and 0.67 g of n-dodecyl mercaptan were charged. 2-butanone 82.8 g was added and dissolved. After 1.7 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C. and reacted for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. This precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and polymer-5 containing a repeating unit derived from monomer-4, a repeating unit derived from MA-ECp, and a repeating unit derived from MNLA was converted into white. As a solid, 30.9 g was obtained with a yield of 54%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is derived from monomer-4: derived from MA-ECp: derived from MNLA = 32: 33: 35.
The GPC measurement results are Mn = 8,900 and Mw / Mn = 1.9.

4). Synthesis of comparative polymer 4,1 Synthesis of comparative polymer-1 Comparative polymer-1 was synthesized in place of monomer-1 used in the synthesis of polymer-1 described above. did.

  A glass flask was charged with 32.2 g of comparative monomer-1 at room temperature, 9.1 g of MA-ECp, 11.1 g of MNLA and 0.67 g of n-dodecyl mercaptan, and 82.8 g of 2-butanone. Added and dissolved. After 1.5 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C. and reacted for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. This precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and the following comparative weight containing a repeating unit derived from Comparative Monomer-1, a repeating unit derived from MA-ECp, and a repeating unit derived from MNLA as shown below. 25.7 g of Compound-1 was obtained as a white solid in a yield of 49%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is derived from Comparative Monomer-1: MA-ECp: MNLA = 27: 37: 36.
As a result of the GPC measurement, Mn is 9,100 and Mw / Mn is 2.2.

4.2 Synthesis of Comparative Polymer-2 Comparative Polymer-2 was synthesized using Comparative Monomer-2 instead of Monomer-1 used in the synthesis of Polymer-1.

  In a glass flask, 32.0 g of comparative monomer-2, 9.1 g of MA-ECp, 11.1 g of MNLA, and 0.67 g of n-dodecyl mercaptan were charged at room temperature, and 82.8 g of 2-butanone was charged. Added and dissolved. After 1.7 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C. and reacted for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. This precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and the following comparative weight containing a repeating unit derived from comparative monomer-2, a repeating unit derived from MA-ECp and a repeating unit derived from MNLA as shown below. 27.1 g of Compound-2 was obtained as a white solid in a yield of 52%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is derived from comparative monomer-2: derived from MA-ECp: derived from MNLA = 35: 30: 35.
As a result of the GPC measurement, Mn is 8,800 and Mw / Mn is 1.9.

4.3 Synthesis of Comparative Polymer-3 Comparative Polymer-3 was synthesized using Comparative Monomer-3 instead of Monomer-1 used in the synthesis of Polymer-1.

  In a glass flask, 38.8 g of comparative monomer-3, 9.1 g of MA-ECp, 11.1 g of MNLA and 0.67 g of n-dodecyl mercaptan were charged at room temperature, and 82.8 g of 2-butanone was charged. Added and dissolved. After 1.4 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C. and reacted for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. This precipitate was filtered off, dried under reduced pressure at a temperature of 60 ° C., and the following comparative weight containing a repeating unit derived from Comparative Monomer-3, a repeating unit derived from MA-ECp, and a repeating unit derived from MNLA as shown below. 31.9 g of Compound-3 was obtained as a white solid in a yield of 54%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is derived from comparative monomer-3: derived from MA-ECp: derived from MNLA = 33: 33: 34.
As a result of the GPC measurement, Mn is 9,300 and Mw / Mn is 2.2.

4.4 Synthesis of Comparative Polymer-4 Comparative Polymer-4 was synthesized using Comparative Monomer-41 instead of Monomer-1 used in the synthesis of Polymer-1.

  In a glass flask, 41.6 g of comparative monomer-4, 9.1 g of MA-ECp, 11.1 g of MNLA and 0.67 g of n-dodecyl mercaptan were charged at room temperature, and 82.8 g of 2-butanone was charged. Added and dissolved. After 1.4 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C. and reacted for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. This precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and the following comparative weight containing a repeating unit derived from comparative monomer-4, a repeating unit derived from MA-ECp, and a repeating unit derived from MNLA as shown below. 32.1 g of Compound-4 was obtained as a white solid in a yield of 52%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is derived from comparative monomer-4: derived from MA-ECp: derived from MNLA = 27: 37: 36.
As a result of the GPC measurement, Mn is 9,100 and Mw / Mn is 2.2.

4.5 Synthesis of Comparative Polymer-5 In a glass flask, 40.0 g of Comparative Monomer-5 at room temperature, 3-hydroxy-1-adamantyl methacrylate (hereinafter sometimes referred to as MA-HAD) 11.8 g, MNLA 11.1 g and n-dodecyl mercaptan 0.67 g were charged, and 2-butanone 82.8 g was added and dissolved. After 1.4 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas, and the temperature was raised to 75 ° C. and reacted for 16 hours. The solution after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. The precipitate was filtered off and dried under reduced pressure at a temperature of 60 ° C., and the following comparative polymer containing a repeating unit derived from comparative monomer-5, a repeating unit derived from MA-HAD and a repeating unit derived from MNLA was shown below. -5 was obtained as a white solid in 33.0 g yield 52%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol%, and is derived from comparative monomer-5: derived from MA-HAD: derived from MNLA = 35: 30: 35.
As a result of the GPC measurement, Mn is 8,400 and Mw / Mn is 2.0.

4.6 Synthesis of Comparative Polymer-6 Methacrylic acid-1,1,1-trifluoro-2-hydroxy-2- (trifluoromethyl) -6-methylhept-4-yl (in a glass flask at room temperature) (Hereinafter sometimes referred to as MA-IB) 16.8 g, MA-ECp 9.1 g, MNLA 11.1 g and n-dodecyl mercaptan 0.67 g are charged and 2-butanone 82.8 g is added and dissolved. It was. After 1.4 g of AIBN was added as a polymerization initiator and deaerated while being stirred, the inside of the flask was replaced with nitrogen gas and reacted at a temperature of 75 ° C. for 16 hours. The content after completion of the reaction was added dropwise to 620.0 g of n-heptane to obtain a white precipitate. This precipitate was filtered off, dried under reduced pressure at a temperature of 60 ° C., and a comparative polymer-6 containing a repeating unit derived from MA-IB, a repeating unit derived from MA-ECp, and a repeating unit derived from MNLA as shown below. As a white solid, 34.3 g was obtained with a yield of 93%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol%, and is MA-IB origin: MA-ECp origin: MNLA origin = 33: 33: 34.
The measurement results of GPC are 9,800 for Mn and 2.1 for Mw / Mn.

4.7 Synthesis of Comparative Polymer-7 In a glass flask, at room temperature, 10.8 g of MA-HAD, 9.1 g of MA-ECp, 11.1 g of MNLA, n-dodecyl mercaptan ( (Made by Tokyo Chemical Industry Co., Ltd.) 0.54 g was charged, and 65.8 g of 2-butanone was added and dissolved. After adding 1.35 g of AIBN as a polymerization initiator and degassing while stirring, the inside of the flask was replaced with nitrogen gas and reacted at a temperature of 75 ° C. for 16 hours. The content after completion of the reaction was added dropwise to 500.0 g of n-heptane to obtain a white precipitate. This precipitate was separated by filtration, dried under reduced pressure at a temperature of 60 ° C., and a comparative polymer-7 containing a repeating unit derived from MA-HAD, a repeating unit derived from MA-ECp, and a repeating unit derived from MNLA shown below. Was obtained as a white solid in a yield of 90%.

The measurement result of the composition ratio of each repeating unit by the nuclear magnetic resonance spectrum is expressed in mol% and is MA-HAD-derived: MA-ECp-derived: MNLA-derived = 35: 35: 30.
The GPC measurement results are Mn = 7,600 and Mw / Mn = 1.8.

  Table 1 shows the compositions and molecular weights of Polymers 1 to 5 and Comparative Polymer 1-7.

3. Evaluation of a polymer as a resist.
3.1 Preparation of resist and measurement of contact angle [Preparation of resist]
As shown in Table 2, resists 1-6 and comparative resists 1-7 were prepared using polymers 1-5 and comparative polymers 1-7.

Specifically, as a resist component, triphenylsulfonium nonafluorobutanesulfonate (PAG-1) or triphenylsulfonium trifluoromethanesulfonate (PAG-2), a basic compound as a photoacid generator for each polymer. As a solution, use isopropanolamine (base-1) or triethanolamine (base-2) and add propylene glycol monomethyl ether acetate (PGMEA) or 4-methyl-2-pentanol (MIBC) as a solvent. did. The composition ratio of the resist was expressed in parts by mass so that the ratio of polymer: photoacid generator: basic substance: solvent was 100: 5: 1: 900.
[Resist film formation]
An antireflection film solution (manufactured by Nissan Chemical Industries, Ltd., product number ARC29A) was applied to a silicon wafer, and then dried at 200 ° C. for 60 seconds to provide an antireflection film having a thickness of 78 nm. Next, each of the resist solutions described above is filtered through a 0.2 μm membrane filter, applied onto the antireflection film at a rotation speed of 1,500 rpm using a spinner, and dried on a hot plate at 100 ° C. for 90 seconds to form a resist film. Formed.
[Contact angle measurement]
The contact angle of water droplets was measured for each resist film on the obtained silicon wafer using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.). The results are shown in Table 2. In immersion exposure lithography, a resist film having a high contact angle does not enter water into the film and causes few watermark defects.

Resist films made of Resist-1 to 6 and Comparative Resists 4 to 5 containing compositions 1 to 5 and Comparative Polymers 4 to 5 containing hexafluoroisopropanol groups in the structure have hexafluoroisopropanol groups in the structure. A contact angle is high with respect to the resist film by the comparative resist 7 which uses the comparative polymer 7 which does not contain as a composition.
3.2 Resist developer solubility and resist pattern resolution For resists 1 to 6 and comparative resists 1 to 7 shown in Table 2, the resist developer solubility and the resolution of the resulting resist pattern were evaluated.
[Evaluation of developer solubility]
A silicon wafer on which a resist film was formed by applying each resist was immersed in an alkaline developer at room temperature for 60 seconds, and the solubility in the developer was tested. As the alkali developer, an aqueous tetramethylammonium hydroxide solution (hereinafter referred to as “a”) having a concentration of 2.38% by mass, which is standardly used in lithography, was used. The solubility of the resist film was determined by measuring the film thickness of the resist film after immersion with a light interference type film thickness meter. When the resist film has completely disappeared, it is `` soluble '', when the resist film remains partially, `` partially remains '', and when there is no change in the resist film thickness, it is `` insoluble '' did. The results are shown in Table 3.
[Evaluation of resist pattern resolution]
A silicon wafer on which a resist film is formed by applying each resist is pre-baked at 100 ° C. for 60 seconds, and then the photomask pattern is transferred through the photomask at an oscillation wavelength of 193 nm using an argon fluoride excimer laser. The exposure was as follows. Pure water was dropped for 2 minutes while rotating the exposed silicon wafer. Thereafter, post-exposure baking was performed at 120 ° C. for 60 seconds, and then development was performed using TMAH as an alkaline developer to obtain a resist pattern.

The obtained resist pattern was observed with a scanning electron microscope (SEM), and the resolution was evaluated based on whether or not a 30 nm line and space could be formed, and the line edge roughness (LER) of the pattern as observed from above the resist pattern. . For line and space line patterns, the case where the cross section perpendicular to the substrate is rectangular is good, the case where the cross section is trapezoidal (tapered) or skirted is acceptable, while the line is broken due to collapse of the pattern or poor resolution. The case where an and-space was formed was not allowed. The results are shown in Table 3.
[Evaluation of line edge roughness (LER)]
LER is measured using a critical dimension scanning electron microscope (CD-SEM) specialized for semiconductors, and the pattern edge position is detected two-dimensionally from the top of the resist pattern, and variations in the position are detected. Was quantified as LER. The smaller the LER, the less the variation of the pattern edge from the straight line to the unevenness is preferable. Specifically, using the white band width detected by the CD-SEM, measure the line width of a portion of 70% of the height from the bottom of the pattern to the top surface, and measure the standard deviation 3σ of these values. The value of LER was used. In general, the measured value of LER is desirably 4.0 nm or less. “> 5.0” in Table 3 means that the measured value of LER is larger than 5.0 nm.
The results are shown in Table 3.

  The resists 1 to 6 and the comparative resists 1 to 7 were all insoluble in an alkaline developer in an unexposed state, and became soluble after exposure. This indicated that all tested resists had a dissolution contrast as a photosensitive resin.

  As shown in Table 3, when resists 1 to 6 were used, a desired rectangular pattern was formed, and good resolution was exhibited. On the other hand, Comparative resists 1 to 7 were impossible because they could not form a rectangle.

  In the LER measurement, the resist pattern using the resist-1 has a smaller LER measurement value than the turn using the comparative resist-1, the comparative resist-4, and the comparative resist-7, and has excellent resist pattern roughness. The resolution was higher.

  The fluorine-containing polymer of the present invention has a hexafluoroisopropanol group, so that it easily dissolves in a developer when used as a top coat and has water repellency, and has no linear or molecular chain carbon. Since the roughness is kept low, it is presumed that this is effective not only as a resist component but also as a topcoat component.

  Advances in the design technology of optical systems in exposure have improved the resolution of projection lenses and the like in steppers (reduction projection type exposure apparatuses), and the resolution of resist patterns obtained in lithography has become finer. The resolution of the projection lens used in the stepper is expressed by the numerical aperture NA. However, in the air, the port opening number of 0.9 is regarded as a physical limit and has already been achieved in the stepper. Yes. Therefore, immersion exposure has been developed in which the numerical aperture is increased to 1.0 or more by filling the space between the lens and the wafer with a medium having a higher refractive index than air. In immersion exposure, even if light is irradiated through a lens using a light source of the same wavelength by changing the medium in the exposure space between the lens and the resist film from air having a refractive index of 1 to pure water having a refractive index of 1.44. It is possible to form a resist pattern having a higher resolution and an excellent depth of focus, which can cope with a shorter wavelength from the visible region to the ultraviolet region, and is used for obtaining a higher definition resist pattern.

  However, various problems have been pointed out since the resist film comes into contact with water in immersion exposure. In particular, resist pattern shape due to dissolution of water in the resist pattern due to swelling of water, acid generated in the film by exposure, and amine compound added as an acid quencher to improve the resolution of the resist pattern. Deterioration etc. becomes a problem.

  In order to prevent these problems from occurring, it is effective to provide a water-resistant upper layer film (hereinafter sometimes referred to as a top coat) on the resist film in order to separate the resist film and water. Furthermore, providing a top coat is also important for improving the throughput (throughput) of the stepper. That is, in order to finish the immersion exposure in a short time, it is necessary to leave no water on the resist film after the exposure, and increasing the water repellency on the surface by the top coat reduces the number of defects. However, the top coat tends to be less soluble in the developer as the water repellency increases.

  Patent Document 8 discloses a topcoat composition containing a polymer compound having a hexafluoropropanol group in its structure, which is easily soluble in a developer when used as a topcoat and has water repellency.

Claims (9)

A fluorine-containing polymer comprising a repeating unit represented by the formula (1).

(In the formula, R ¹ is a hydrogen atom or a protecting group. A is a group of any one of the following formulas (2A) to (2C) and (3A) to (3C)).

(Wherein R ² and R ³ are each independently a hydrogen atom, a hydroxyl group or a thiol group.)

(In the formula, R ⁴ and R ⁵ are each independently a hydrogen atom, a hydroxyl group or a thiol group, and R ⁶ is an oxygen atom or a sulfur atom.) The fluorine-containing polymer according to claim 1, wherein A is a group represented by formulas (2A) to (2C), and R ² and R ³ are hydrogen atoms. Furthermore, the fluorine-containing polymer of Claim 1 or Claim 2 containing repeating units other than the repeating unit represented by Formula (1). A resist comprising the fluoropolymer according to any one of claims 1 to 3. Furthermore, the resist of Claim 4 containing an acid generator, a basic compound, or an organic solvent. The resist according to claim 5, wherein the organic solvent is an alcohol solvent having 5 to 20 carbon atoms. Applying the resist according to claim 4 on a substrate to form a resist film;
Irradiating the resist film with a high energy beam having a wavelength of 300 nm or less via a photomask, and transferring the pattern of the photomask to the resist film;
Including a step of obtaining a resist pattern to be developed using a developer.
A method for forming a resist pattern. A fluorine-containing polymerizable monomer represented by the formula (4).

(In the formula, R ¹ is a hydrogen atom or a protecting group. A is a group of any one of the following formulas (2A) to (2C) and (3A) to (3C)).

(Wherein R ² and R ³ are each independently a hydrogen atom, a hydroxyl group or a thiol group.)

(In the formula, R ⁴ and R ⁵ are each independently a hydrogen atom, a hydroxyl group or a thiol group, and R ⁶ is an oxygen atom or a sulfur atom.) The fluorine-containing monomer according to claim 8, wherein A is a group represented by formulas (2A) to (2C), and R ² and R ³ are hydrogen.