JP2017145383A - Fluorine-containing monomer, fluorine-containing polymer prepared therewith, chemically amplified resist prepared therewith, and pattern forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemically amplified resist, in which, when forming a resist pattern with an organic solvent as a developer in photolithography with high energy rays, a difference in resist solubility between an exposed portion and an unexposed portion is improved, and sufficient dry etching resistance is secured.SOLUTION: A fluorine-containing polymer comprises a repeating unit represented by formula (1) (A is a C3-25 alicyclic hydrocarbon group or a C 5-25 aromatic hydrocarbon group; Ris an acetal bond, a hemiacetal bond or a hemiacetal ester bond).SELECTED DRAWING: None

Description

  The present invention relates to a novel fluorine-containing monomer, a fluorine-containing polymer using the same, a chemically amplified resist using the same, and a pattern forming method using the same, and in particular, a negative type using an organic solvent as a developer. The present invention relates to a chemically amplified resist and a pattern forming method using the same.

  A resist used for pattern formation by a photolithography method in a semiconductor manufacturing process is required to have high sensitivity, enable fine processing, and have good adhesion to a substrate.

  There are two types of resists: positive resists and negative resists. Positive resist forms a resist film on a silicon wafer or glass substrate, and when the resist film is irradiated with high energy rays through a photomask or the like on which a pattern has been drawn in advance, the exposed part dissolves in the developer and is not exposed. This is a resist to which the pattern of the photomask is transferred by leaving the portion as a resist pattern. On the other hand, the negative resist is a resist to which the pattern of the photomask is transferred when the unexposed portion is dissolved in the developer and the exposed portion remains as a resist pattern.

  The formed resist pattern is required to have etching resistance so that the resist is not immersed in the etching gas in an etching process in which the resist pattern is transferred and formed on the semiconductor substrate with the etching gas.

  Also, in the photolithography method, there is a tendency to use high-energy rays that are short-wave electromagnetic waves such as ultraviolet rays and X-rays or electron beams, and the resist pattern is miniaturized accordingly. Along with miniaturization, the resist has a margin of depth of focus (hereinafter referred to as DOF), and has little pattern line edge roughness (hereinafter referred to as LER) and resolution. Therefore, it has been required to have excellent high definition.

  As a resist suitable for fine processing by exposure with high energy rays, a chemically amplified resist can be exemplified. A chemically amplified resist contains a photoacid generator that generates an acid upon irradiation with high energy rays, and the acid labile group in the resist structure is dissociated using the acid generated in the exposed area as a catalyst. This resist forms a resist pattern by causing a difference in solubility in a developing solution between an exposed portion and a non-exposed portion.

  As the pattern becomes finer, the chemically amplified resist is required to further reduce LER. Generally, the chemically amplified resist before being applied to the substrate is in a solution state, and after being applied to the substrate, it is heated and dried (baked) to form a resist film. The resist film comprises a photoacid generator that generates an acid upon exposure, a polymer that changes the solubility of the exposed portion in the developer by dissociating an acid labile group by the action of the generated acid, and a photoacid generator And a solvent for dissolving the polymer.

The resist pattern is formed by applying a chemically amplified resist in the form of a solution to a substrate with a spin coater or the like to form a resist film, baking it, and then exposing through a photomask, etc., followed by baking and patterning the resist film using a developer. Is obtained. In general, an alkaline tetramethylammonium hydroxide (N (CH ₃ ) ₄ OH or below, sometimes referred to as TMAH) aqueous solution is used as a developer used for forming a resist pattern.

  Patent Documents 1 and 2 disclose using an organic solvent instead of a TMAH aqueous solution as a developing solution as a means for reducing LER.

  In pattern formation by photolithography using high energy rays, for example, short wavelength ultraviolet rays using an ArF excimer laser with a wavelength of 380 nm or less (oscillation wavelength 193 nm), KrF excimer laser (oscillation wavelength 248 nm), or an electron beam, or an electron beam However, when forming a negative pattern using an organic solvent as a developing solution, if the solubility of the unexposed area in the developing solution is insufficient, the LER increases and a high-definition pattern cannot be obtained. It was. Regarding this, Patent Document 2 discloses that the LER of the pattern is lowered by using an organic solvent such as butyl acetate as a developer.

Patent Document 3 discloses a photoresist composition having an acrylate monomer and a methacrylate monomer having a fluoroalcohol group containing a hexafluoroisopropanol group (—C (CF ₃ ) ₂ OH). It is used as a positive or negative photoresist of resolution. According to the example, the negative photoresist described in Patent Document 3 contains a cross-linking agent such as glycouril, and the exposed portion of the resist contains a cross-linking agent such as glycouril and an acrylate monomer or a methacrylate monomer by the action of an acid. By reacting and cross-linking with the polymer obtained by polymerization, the solubility in an alkaline TMAH aqueous solution used as a developer is lowered, and it acts as a negative photoresist.

  Patent Document 4 discloses an upper layer film-forming composition coated on a photoresist film, the composition comprising a resin dissolved in a developer for developing the photoresist film, an acid and a radiation-sensitive acid generator And a resin having a repeating unit having a fluoroalcohol group containing a hexafluoroisopropanol group is used as the resin.

JP 2001-215731 A JP 2009-25723 A JP 2004-46098 A JP 2006-308814 A

  In the present invention, when an organic solvent is used as a developing solution in a photolithography method using a high energy beam with a chemically amplified resist, a difference in solubility between the exposed portion and the unexposed portion of the resist film in the organic solvent is large. An object is to provide a chemically amplified resist that can be formed.

  In addition, an object of the present invention is to provide a fluorinated polymer constituting the chemically amplified resist and a fluorinated monomer used for polymerizing the fluorinated polymer.

  Dry etching is a method of etching a material with an etching gas, ions, or radicals that are reactive gases, and the dry etching step is a step of performing dry etching. The dry etching process in the photolithography method is a method of exposing and developing a resist film to form a resist pattern, and then etching the substrate or the lower layer film in the exposed portion of the pattern with plasma containing radicals, thereby removing the resist pattern from the substrate or the resist pattern. This is a step of transferring to the lower layer film.

  In the chemically amplified resist, the resist pattern is required to have dry etching resistance without being immersed in an etching gas.

The present inventors synthesized a novel fluorine-containing monomer that can be used in a negative resist as a chemically amplified resist using an organic solvent as a developer and a fluorine-containing polymer obtained by polymerizing the same.
The negative resist containing the fluoropolymer has a large solubility difference between the exposed portion and the unexposed portion of the resist when forming a resist pattern using an organic solvent as a developer in a photolithography method using high energy rays. In addition, when dry etching is performed, sufficient etching resistance is exhibited.

  When used as a chemically amplified resist, the fluoropolymer of the present invention has an alicyclic structure or an aromatic ring structure on the main chain side left after exposure with high energy rays, and is acid-decomposable that dissociates after exposure. There is a hexafluoroisopropanol group on the base side. When a resist pattern is formed using an organic solvent as a developer after irradiation with high energy, the unexposed portion of the resist film having a hexafluoroisopropanol group exhibits sufficient solubility in the developer, whereas the hexafluoroisopropanol group Since the unexposed portion of the resist film in which the film disappears does not exhibit solubility, it is assumed that the solubility difference between the exposed portion and the unexposed portion of the resist film can be increased.

  In addition, when the chemically amplified resist of the present invention is used, it is presumed that the resist pattern can exhibit sufficient etching resistance in the dry etching process because the alicyclic structure or aromatic ring structure remains in the resist after pattern formation. The

That is, this invention consists of the following invention 1-10.
[Invention 1]
A fluorine-containing polymer containing a repeating unit represented by the following formula (1).

(In the formula, A is an organic group having an alicyclic hydrocarbon group having 3 to 25 carbon atoms or an aromatic hydrocarbon group having 5 to 25 carbon atoms, and any number of hydrogen atoms in the organic group is a hydroxy group. May be substituted with an alkoxy group having 1 to 4 carbon atoms, an acetoxy group or an alkyl group having 1 to 4 carbon atoms, and each R ¹ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. And R ² each independently represents an acetal bond, a hemiacetal bond or a hemiacetal ester bond, and R ³ each independently represents an aliphatic hydrocarbon group having 1 to 15 carbon atoms or an aromatic hydrocarbon group having 5 to 15 carbon atoms. Or an organic group in which a plurality of these groups are linked, n is an integer of 1 to 3, and m is an integer of 1 to 3.)
[Invention 2]
The fluoropolymer of Invention 1, wherein A is an adamantylene group.
[Invention 3]
Wherein R ² is an acetal bond represented by the formula (4), the fluorine-containing polymer of the invention 1-2.

(R ⁵ and R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms, or a hydrocarbon group in which these groups are connected to each other to form a ring.)
[Invention 4]
Furthermore, olefins containing double bonds, fluorine-containing olefins, acrylic esters, methacrylic esters, fluorine-containing acrylic esters, fluorine-containing methacrylates, norbornene compounds, fluorine-containing norbornene compounds, styrene compounds, fluorine-containing styrene compounds The fluorine-containing polymer of inventions 1 to 3, comprising a repeating unit obtained by cleaving a double bond of one or more monomers selected from vinyl ether and fluorine-containing vinyl ether.
[Invention 5]
A resist comprising the fluoropolymer of inventions 1 to 4, a solvent, and a photoacid generator.
[Invention 6]
A step (A) of applying the resist of the invention 5 on a substrate;
A step (B) of exposing with a high energy beam which is an electromagnetic wave or an electron beam having a wavelength of 380 nm or less through a photomask after the heat treatment;
The pattern formation method including the process (C) which develops using a developing solution, without heat-processing or after heat-processing.
[Invention 7]
The pattern formation method of the invention 6 whose process (B) is a process (B) by the immersion lithography method which used the laser beam of wavelength 193nm or wavelength 243nm for a high energy ray.
[Invention 8]
The pattern formation method of the invention 6 whose process (B) is a process (B) using the soft X-ray light of wavelength 10nm or more and 14nm or less for a high energy ray.
[Invention 9]
A fluorine-containing monomer represented by the following formula (2).

(In the formula, A is an organic group having an alicyclic hydrocarbon group having 3 to 25 carbon atoms or an aromatic hydrocarbon group having 5 to 25 carbon atoms, and any number of hydrogen atoms in the organic group is a hydroxy group. May be substituted with an alkoxy group having 1 to 4 carbon atoms, an acetoxy group or an alkyl group having 1 to 4 carbon atoms, and each R ¹ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. And R ² each independently represents an acetal bond, a hemiacetal bond or a hemiacetal ester bond, and R ³ each independently represents an aliphatic hydrocarbon group having 1 to 15 carbon atoms or an aromatic hydrocarbon group having 5 to 15 carbon atoms. Or an organic group in which a plurality of these groups are linked, n is an integer of 1 to 3, and m is an integer of 1 to 3.)

  In the fluorinated polymer of the present invention, when a resist pattern is formed using an organic solvent as a developer in a photolithography method using a high energy beam using a chemically amplified resist containing the same, an exposed portion and an unexposed portion are formed. The difference in solubility between resists is large, and sufficient etching resistance is exhibited when dry etching is performed.

  Hereinafter, embodiments of the fluorine-containing monomer and the fluorine-containing polymer of the present invention, a chemically amplified resist using the same, and a pattern forming method thereof will be described. The present invention is described below. The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like to the following embodiments are also included in the scope of the present invention without departing from the spirit of the present invention.

  In the present invention, an alkyl group or an alkylene group means a linear, branched or cyclic alkyl group or an alkylene group unless otherwise specified.

  In the present invention, the “lower alkyl group” means an alkyl group having 1 to 4 carbon atoms in the case of a chain, and an alkyl group having 3 to 7 carbon atoms in the case of a cyclic compound.

  In the present invention, the alicyclic ring means a monocyclic or polycyclic aliphatic hydrocarbon structure. Any carbon atom of the aliphatic hydrocarbon structure may be a group substituted with an oxygen atom, a sulfur atom, a carbonyl group or an imino group, and may contain a non-aromatic double bond.

  Specific alicyclic rings are exemplified below.

  In the present invention, the high energy beam refers to an electromagnetic wave having a wavelength of 380 nm or less or an electron beam that acts on a resist to generate an acid. Soft X-rays refer to electromagnetic waves having a wavelength of 10 nm or more and 14 nm or less. Specific examples include ultraviolet light using an ArF excimer laser (193 nm) and a KrF excimer laser (248 nm) as a light source.

  The fluoropolymer of the present invention is a fluoropolymer represented by the following formula (1).

(In the formula, A is an organic group having an alicyclic hydrocarbon group having 3 to 25 carbon atoms or an aromatic hydrocarbon group having 5 to 25 carbon atoms, and any number of hydrogen atoms in the organic group is a hydroxy group. May be substituted with an alkoxy group having 1 to 4 carbon atoms, an acetoxy group or an alkyl group having 1 to 4 carbon atoms, and each R ¹ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. And R ² each independently represents an acetal bond, a hemiacetal bond or a hemiacetal ester bond, and R ³ each independently represents an aliphatic hydrocarbon group having 1 to 15 carbon atoms or an aromatic hydrocarbon group having 5 to 15 carbon atoms. Or an organic group in which a plurality of these groups are linked, n is an integer of 1 to 3, and m is an integer of 1 to 3.)

  The fluorine-containing polymer containing the repeating unit represented by the formula (1) homopolymerizes or copolymerizes the fluorine-containing monomer represented by the formula (2) as shown in the following reaction formula (1). Can be obtained.

  The fluorine-containing polymer is used together with a photoacid generator, a solvent and the like to form a chemically amplified resist. When the obtained resist is applied to a substrate to form a resist film and irradiated with high energy rays through a photomask or the like, the acid labile group is eliminated as a compound (7) from the fluoropolymer contained in the resist, and the formula It becomes a polymer containing the repeating unit represented by (3). The polymer containing the repeating unit represented by the formula (3) in the exposed part is insoluble in an organic solvent and contains a repeating unit having an acid labile group represented by the formula (1) in the unexposed part. By dissolving the fluoropolymer in an organic solvent, a negative resist pattern to which the photomask pattern is transferred is formed.

(In the reaction formula, A, R ^{1 to} R ⁶ , n and m are as described above. X is a hydroxy group or a carboxylic acid group.)

  Since the fluorinated polymer contained in the formed resist pattern has an alicyclic structure or an aromatic ring structure, it has a specific effect that it can exhibit sufficient etching resistance against an etching gas in a dry etching process. Have.

  Whereas the resist containing the fluoropolymer of the present invention is a negative resist using an organic solvent as a developer, a chemically amplified resist using a TMAH aqueous solution as a developer used in the past is often irradiated with light. This is a positive resist in which the remaining part dissolves.

1. Fluorinated monomer represented by formula (2) The following fluorinated monomer represented by formula (2) will be described.

(A, R ^{1 to} R ³ , n and m are as described above.)

1.1 Organic group A
Since the fluorine-containing monomer represented by the formula (2) has the organic group A, a polymer containing a repeating unit represented by the formula (3) is generated after the exposure, and is used as an etching gas in the dry etching process. On the other hand, the resist pattern shows etching resistance.

  The skeleton of the organic group A represented by the formula (2) is an alicyclic hydrocarbon group having 3 to 25 carbon atoms or an aromatic hydrocarbon group having 5 to 25 carbon atoms. The alicyclic hydrocarbon group or aromatic hydrocarbon group may be monocyclic or polycyclic, and any hydrogen atom in the group may be substituted.

  In the fluorine-containing monomer which is a precursor of the fluorine-containing polymer contained in the chemically amplified resist of the present invention, the organic group A is preferably a divalent group selected from an adamantylene group, a norbornylene group, a phenylene group and a naphthylene group. An organic group, more preferably an adamantylene group or a phenylene group, and particularly preferably an adamantylene group.

  Hereinafter, the case where the organic group A is an alicyclic hydrocarbon group and the case where it is an aromatic hydrocarbon group will be individually described.

[Alicyclic hydrocarbon group]
The alicyclic hydrocarbon group may be monocyclic or polycyclic, and specific examples thereof include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 3 or more carbon atoms. Preferably it is C3-C20, Most preferably, it is C5-C15. In these alicyclic hydrocarbon groups, any hydrogen atom in the group may be substituted with a substituent described later.
<Monocyclic alicyclic hydrocarbon group>
The monocyclic alicyclic hydrocarbon group is preferably an alicyclic hydrocarbon group having 3 to 12 carbon atoms, and particularly preferably an alicyclic hydrocarbon group having 3 to 7 carbon atoms. Specifically, a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclodecanylene group, or a cyclododecanylene group can be exemplified.
<Polycyclic alicyclic hydrocarbon group>
Specific examples of the polycyclic alicyclic hydrocarbon group include adamantylene group having 7 to 15 carbon atoms, noradamantylene group, decanylene group, tricyclodecanylene group, tetracyclododecanylene group, norbornylene group, cedrol. Can be exemplified by groups in which hydrogen atoms are dissociated. The alicyclic hydrocarbon group may have a spiro ring and is preferably a C 3-6 spiro ring.
<Substituent>
The hydrogen atom of the alicyclic hydrocarbon group may be substituted, and examples of the substituent include a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, an acetoxy group, or an alkyl group having 1 to 4 carbon atoms. Preferably a hydroxy group, a methoxy group, an acetoxy group or a methyl group, more preferably a hydroxy group or an acetoxy group.

  Specific examples of the alkoxy group having 1 to 4 carbon atoms include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, 1-methylpropoxy group and tert-butoxy group. Groups can be exemplified.

  Specific examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, 1-methylpropyl group, and tert-butyl. Groups can be exemplified.

[Aromatic hydrocarbon group]
The aromatic hydrocarbon group may be monocyclic or condensed polycyclic, has 5 to 25 carbon atoms, and a hydrogen atom in the group may be substituted with a substituent.
<Monocyclic aromatic hydrocarbon group>
The monocyclic aromatic hydrocarbon group has 5 to 12 carbon atoms, and more preferably 6 to 10 carbon atoms. Specifically, phenylene group, biphenylene group, terphenylene group, o-tolylene group, m-tolylene group, p-tolylene group, p-hydroxyphenylene group, p-methoxyphenylene group, mesitylene group, o-cumenylene group, Examples include 2,3-xylylene group, 2,4-xylylene group, 2,5-xylylene group, 2,6-xylylene group, 3,4-xylylene group, and 3,5-xylylene group.
<Condensed polycyclic aromatic hydrocarbon group>
The condensed polycyclic aromatic hydrocarbon group has 5 to 25 carbon atoms. Specifically, pentalene, indene, naphthalene, azulene, heptalene, biphenylene, indacene, acenaphthylene, fluorene, phenalene, phenanthrene, anthracene, fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, naphthacene, picene, Examples include condensed polycyclic aromatic hydrocarbon groups obtained by dissociating hydrogen atoms from perylene, pentaphen, pentacene, tetraphenylene, hexaphen, hexacene, rubicene, coronene, trinaphthylene, heptaphene, heptacene, pyrantrene, or ovalene. .
<Substituent>
The hydrogen atom of the aromatic hydrocarbon group may be substituted, and examples of the substituent include a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, an acetoxy group, or an alkyl group having 1 to 4 carbon atoms. Is a hydroxy group, a methoxy group, an acetoxy group or a methyl group, more preferably a hydroxy group or an acetoxy group.

  Specific examples of the alkoxy group having 1 to 4 carbon atoms include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, 1-methylpropoxy group and tert-butoxy group. Groups can be exemplified.

  Specific examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, 1-methylpropyl group, and tert-butyl. Groups can be exemplified.

1.2 Linking group R ²
When the fluorine-containing polymer represented by the formula (1) obtained by polymerizing or copolymerizing the fluorine-containing monomer represented by the formula (2) is used as a resist, the linking group R ² in the fluorine-containing polymer is a photoacid. The acid-decomposable group containing a hexafluoroisopropanol group is cleaved by the acid generated from the generator, and the solubility of the fluoropolymer in the organic solvent used as the fluorine-containing developer is lowered.

Examples of the linking group R ^{2 that} is cleaved by an acid include the following acetal bonds, hemiacetal bonds, and hemiacetal ester bonds.
<Acetal bond>
Specifically, the acetal bond can be an acetal bond represented by the following formula (4).

<Hemiacetal bond>
Specifically as a hemiacetal bond, the hemiacetal bond represented by the following formula | equation (5) can be shown.

<Hemiacetal ester bond>
Specifically as a hemiacetal ester bond, the hemiacetal ester bond represented by the following formula | equation (6) can be shown.

[For ^R 5 ^{~R 7]}
R ⁵ to R ⁷ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms, or a R ⁵ a hydrocarbon group these groups are linked to each other to form a ring A ring may be formed from R ⁶ .

In the fluorine-containing monomer that is a precursor of the fluorine-containing polymer contained in the chemically amplified resist of the present invention, R ^{5 to} R ⁷ contained in the linking group R ² are preferably each independently a hydrogen atom or a methyl group. , Ethyl group, n-propyl group or i-propyl group, particularly preferably a hydrogen atom or a methyl group.

When the monovalent organic group represented by R ^{5 to} R ⁷ is a linear hydrocarbon group, R ⁵ and R ⁶ are connected to form a ring to form a divalent alicyclic hydrocarbon group. Each case will be described.
<Linear hydrocarbon group>
Specific examples of the linear hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and an i-butyl group, which are alkyl groups having 1 to 4 carbon atoms. , 1-methylpropyl group, and tert-butyl group.
<Alicyclic hydrocarbon group>
Specific examples of the divalent alicyclic hydrocarbon group in which R ⁵ and R ⁶ are linked to form a ring include a cyclopentyl group and a cyclohexyl group.

1.3 Organic group R ³
The organic group R ³ is an aliphatic hydrocarbon group having 1 to 15 carbon atoms, an aromatic hydrocarbon group having 5 to 15 carbon atoms, or an organic group in which a plurality of them are connected.

In the fluorine-containing monomer which is a raw material compound of the chemically amplified resist of the present invention, the organic group R ³ is preferably ethylene, i-butylethylene, propylene, i-propylene, tert-butylene, cyclohexylene or norbornylene. More preferably ethylene, i-butylethylene, i-propylene or cyclohexylene, particularly preferably ethylene, i-butylethylene or cyclohexylene.

The case where the organic group R ³ is an aliphatic hydrocarbon group and the case where it is an aromatic hydrocarbon group will be described.

[Aliphatic hydrocarbon group]
The aliphatic hydrocarbon group having 1 to 15 carbon atoms may be linear, branched or cyclic, preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, more preferably 2 to 2 carbon atoms. 8 aliphatic hydrocarbon groups.
<Linear or branched aliphatic hydrocarbon group>
Specific examples of the linear or branched aliphatic hydrocarbon group include methylene group, ethylene group, ethylethylene group, n-propylethylene group, i-propylethylene group, n-butylethylene group, i -Butylethylene group, tert-butylethylene group, n-propylene group, i-propylene group, n-butylene group, 1-methylpropylene group, 2-methylpropylene group, tert-butylene group, n-pentylene group, i- Pentylene group, 1,1-dimethylpropylene group, 1-methylbutylene group, 1,1-dimethylbutylene group, n-hexylene group, n-heptylene group, i-hexylene group, n-octylene group, i-octylene group, Examples include 2-ethylhexylene group, n-nonylene group, n-decylene group, n-undecylene group and n-dodecylene group.
<Alicyclic hydrocarbon group>
The alicyclic hydrocarbon group may be monocyclic or polycyclic and may have a substituent. Specifically, the alicyclic hydrocarbon group has a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 3 or more carbon atoms. Can be illustrated. An alicyclic hydrocarbon group having 3 to 15 carbon atoms is preferable, and an alicyclic hydrocarbon group having 5 to 15 carbon atoms is particularly preferable.
<Monocyclic alicyclic hydrocarbon group>
The monocyclic alicyclic hydrocarbon group is preferably a monocyclic alicyclic hydrocarbon group having 3 to 12 carbon atoms, more preferably a monocyclic alicyclic hydrocarbon group having 3 to 7 carbon atoms. is there. Specific examples include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclodecanylene group, a cyclododecanylene group, or a 4-tert-butylcyclohexylene group. it can.
<Polycyclic alicyclic hydrocarbon group>
Examples of the polycyclic alicyclic hydrocarbon group include a norbornylene group having 7 to 15 carbon atoms, a divalent residue of bicyclo [2.2.2] octane, a divalent residue of decalin, and tricyclodecanylene. It can be illustrated.

[Aromatic hydrocarbon group]
The aromatic hydrocarbon group having 5 to 15 carbon atoms may be monocyclic or condensed polycyclic.
<Monocyclic or condensed polycyclic aromatic hydrocarbon group>
The monocyclic aromatic hydrocarbon group is preferably an aromatic hydrocarbon group having 5 to 12 carbon atoms, and more preferably an aromatic hydrocarbon group having 5 to 8 carbon atoms. Specifically, phenylene group, biphenylene group, terphenylene group, o-tolylene group, m-tolylene group, p-tolylene group, mesitylene group, o-cumenylene group, 2,3-xylylene group, 2,4-xylylene group Examples thereof include a group, 2,5-xylylene group, 2,6-xylylene group, 3,4-xylylene group or 3,5-xylylene group.

  Specific examples of the condensed polycyclic aromatic hydrocarbon group include groups in which a hydrogen atom is dissociated from pentalene, indene, naphthalene, azulene, heptalene, biphenylene, indacene, acenaphthylene, fluorene, phenalene, phenanthrene, anthracene, and fluoranthene. Can be illustrated.

2. Specific example of fluorine-containing monomer represented by formula (2) As a raw material compound of the fluorine-containing polymer contained in the chemically amplified resist of the present invention, a particularly preferable fluorine-containing monomer is polymerized to form a fluorine-containing polymer. When used with a chemically amplified resist, it has a large difference in solubility in the organic solvent that is the developer in the exposed and unexposed areas of the resist film, and has resistance to etching in the etching process. It is a fluorine-containing monomer that gives a chemically amplified resist.

  Examples of the fluorine-containing monomer represented by the formula (2) include the following fluorine-containing monomers.

  The following fluorine-containing compounds can be exemplified as particularly preferred fluorine-containing monomers useful as a raw material compound for the chemically amplified resist of the present invention.

Particularly preferably, when A is an adamantylene group as a linking group between a methacrylic acid structure and a hexafluoroisopropanol group, a chemically amplified resist exhibiting sufficient etching resistance can be obtained in dry etching. R ² in the linking group is an acid-decomposable group that is decomposed by the generation of an acid from the photoacid generator by irradiation with high energy rays, and preferably an acid is generated by making R ^{2 an} acetal bond. Therefore, a chemically amplified resist having a large solubility difference between the exposed and unexposed resists can be obtained.

3. Production method of fluorine-containing monomer represented by formula (2) Next, a production method of the fluorine-containing monomer represented by formula (2) will be described.

In the production of the fluorine-containing monomer represented by the formula (2), when R ² is an acetal bond represented by the formula (4) or a hemiacetal ester bond represented by the formula (6), ^The reaction route differs depending on whether ² is a hemiacetal bond represented by the formula (5).

(R ^{5 to} R ⁷ are as described above.)

3.1 Fluorine-containing monomer represented by formula (2-1) in which linking group R ² is an acetal bond represented by formula (4) or a hemiacetal ester bond represented by formula (6) The following reaction formula (2) is a formula (2-1) in which the linking group R ² is an acetal bond represented by the above formula (4) or a hemiacetal ester bond represented by the above formula (6). It is an example of the reaction path | route at the time of manufacturing the fluorine-containing monomer represented.

(A, R ¹ and R ³ have the same meaning as in formula (2), and R ⁵ and R ⁶ have the same meaning as in formula (4). R ⁸ and R ⁹ are each independently a hydrogen atom or a carbon number of 1 to 4 is a monovalent hydrocarbon group, B is an ether bond or an ester bond, and X is a hydroxy group or a carboxyl group.)

  As shown in the upper stage of the reaction formula (2), the production of the fluorine-containing monomer represented by the formula (2-1) is performed using an ether represented by the formula (8) and a hexagon represented by the formula (9). A first step of producing an ether represented by formula (10) by reacting an alcohol having a fluoroisopropanol group, an alcohol or carboxylic acid represented by formula (11), and a formula (10 produced in the first step) The second step of reacting the ether represented by formula (2-1) to obtain the fluorine-containing monomer represented by the formula (2-1).

[First step]
The first step is a step of producing an ether represented by formula (10) by reacting an ether represented by formula (8) with an alcohol having a hexafluoroisopropanol group represented by formula (9). For example, Japanese Patent Application Laid-Open No. 2004-155680, Japanese Patent Application Laid-Open No. 2004-231815, and Japanese Patent Application Laid-Open No. 2004-256562 are disclosed in this process, and can be manufactured according to them.

  As the ether represented by the formula (8), a commercially available one may be used as it is, or it may be prepared according to a known method or a modification thereof.

  Alcohols having a hexafluoroisopropanol group represented by the formula (9) are disclosed in JP-A-2005-206587, JP-A-2005-213215, JP-A-2005-232095, JP-A-2005-239710, and JP-A-2005-239710. A manufacturing method is described in Japanese Patent Application Laid-Open No. 2015-193594 and the like, and manufacturing can be performed in accordance therewith.

The reaction in the first step varies depending on the chemical species of the organic group R ⁵ in the ether represented by the formula (8).

  One example is shown below.

In the ether represented by the formula (8), when the organic groups R ⁵ , R ⁸ , and R ⁹ are hydrogen atoms, the reaction proceeds by an ether exchange reaction with the alcohol represented by the formula (9). The ether represented by (10) is obtained. The amount of the ether represented by the formula (8) to be reacted with the alcohol represented by the formula (9) is not particularly limited, but is preferably based on 1 mol of the alcohol represented by the formula (9). Is 0.1 mol or more and 50 mol or less, more preferably 1 mol or more and 30 mol or less, and particularly preferably 5 mol or more and 20 mol or less.

  The reaction proceeds without using a solvent, but it is easier to control the use. Specific examples of the solvent that can be used include dichloroethane, toluene, ethylbenzene, monochlorobenzene, and acetonitrile. These solvents may be used alone or in combination of two or more.

  The reaction temperature is not particularly limited, and is preferably 0 ° C. or higher and 200 ° C. or lower, more preferably 20 or higher and 180 ° C. or lower, and particularly preferably 20 or higher and 100 ° C. or lower. The reaction is preferably carried out with stirring.

  Although the reaction time depends on the reaction temperature, it is preferably 1 minute or more and 100 hours or less, more preferably 30 minutes or more and 50 hours or less, and particularly preferably 1 hour or more and 24 hours or less. It is preferable to use an analytical instrument such as gas chromatography (GC) and set the end point of the reaction to the time when the alcohol represented by the formula (9) as the raw material is consumed.

  In this reaction, a metal catalyst and a ligand can be used.

  Specific examples of the metal catalyst include palladium catalyst or palladium trifluoroacetate as a palladium catalyst, chloro (1,5-cyclooctadiene) iridium dimer as an iridium catalyst, mercury acetate as a mercury catalyst, or ruthenium. Examples of the catalyst include a cobalt catalyst. The amount of the metal catalyst used is preferably 0.0001 mol or more and 10 mol, more preferably 0.001 mol or more and 5 mol or less, with respect to 1 mol of the alcohol represented by the formula (9). It is particularly preferably 0.01 mol or more and 1.5 mol or less.

  Specific examples of the ligand include heterocyclic compounds 2, 2'-bipyridine, and 1,10 phenanthroline.

  After completion of the reaction, an ether represented by the formula (10) can be obtained by extraction, distillation, or column chromatography. Moreover, it can refine | purify by the precision distillation etc. which were obtained as needed.

[Second step]
The alcohol or carboxylic acid represented by the formula (11) is reacted with the ether represented by the formula (10) produced in the first step to obtain a fluorine-containing monomer represented by the formula (2-1). It consists of a second step.

  As the alcohol or carboxylic acid represented by the formula (11), a commercially available product can be used as it is, or it can be prepared by a known method or a modification thereof.

The reaction in the second step differs depending on the chemical species of the organic group of the organic group R ⁵ in the ether represented by the formula (10).

When R ^{5 of the} ether represented by the formula (10) is a hydrogen atom, an addition reaction is performed in the presence of an acid catalyst with the alcohol or carboxylic acid represented by the formula (11), and the ether represented by the formula (2-1) is represented. A fluorine-containing monomer is produced. The amount of the ether represented by the formula (10) that acts on the alcohol or carboxylic acid represented by the formula (11) is 1 mol of the alcohol or carboxylic acid represented by the formula (11). Preferably they are 0.1 mol or more and 20 mol or less, More preferably, they are 0.5 mol or more and 10 mol or less, Especially preferably, they are 0.8 mol or more and 3 mol or less.

  The reaction proceeds even without solvent, but it is easier to control if it is performed in a solvent inert to the reaction. If the solvent used is illustrated, if it is a solvent inactive with respect to reaction, it will not specifically limit. The alcohol or carboxylic acid represented by the formula (3) hardly dissolves in hydrocarbon-based nonpolar solvents such as n-hexane and n-heptane, and it is not preferable to use these solvents alone. Preferred solvents in this reaction include ester solvents, ether solvents, halogen solvents, and polar solvents. Specifically, ester solvents such as ethyl acetate or butyl acetate, ether solvents diethyl ether, diethylene glycol dimethyl ether or tetrahydrofuran, halogen solvents dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, tetrachloroethylene, chlorobenzene Alternatively, orthochlorobenzene, or polar solvents such as acetonitrile, N, N-dimethylformamide, N, N-dimethylimidazolidinone, dimethyl sulfoxide or sulfolane can be exemplified. These solvents may be used alone or in combination of two or more.

  The reaction temperature is preferably in the range of −78 ° C. or higher and 150 ° C. or lower, more preferably −20 ° C. or higher and 120 ° C. or lower, and particularly preferably 0 ° C. or higher and 100 ° C. or lower. The reaction is preferably carried out with stirring.

  Although the reaction time depends on the reaction temperature, it is preferably 1 minute or longer and 100 hours, more preferably 30 minutes or longer and 50 hours or shorter, and particularly preferably 1 hour or longer and 24 hours or shorter. It is preferable to use an analytical instrument such as liquid chromatography (HPLC) and set the end point of the reaction to the time when the alcohol or carboxylic acid represented by the formula (11) as the raw material is consumed.

  In this reaction, an acid catalyst is preferably used. Examples of the acid catalyst include organic acids and inorganic acids. Specific examples include p-toluenesulfonic acid, p-toluenesulfonic acid pyrididium, methanesulfonic acid, trifluoromethanesulfonic acid or camphorsulfonic acid, which are organic acids, and sulfuric acid which is an inorganic acid. The amount of the acid catalyst to be used is preferably 0.01 mol or more and 10 mol or less, more preferably 0.05 mol or more and 1 mol or less with respect to 1 mol of the alcohol or carboxylic acid represented by the formula (11). The amount is not more than mol, and particularly preferably not less than 0.1 mol and not more than 0.3 mol.

After completion of the reaction, the fluorine-containing monomer represented by the formula (2-1) can be obtained by extraction and distillation. If necessary, it can be purified by column chromatography.
3.2 Production of fluorinated monomer represented by formula (2-2) wherein linking group R ² is a hemiacetal bond represented by the above formula (5) The following reaction formula (3) is a linking group R ² is an example of a reaction pathway in the production of fluorine-containing monomer represented by the formula (2-2) is a hemiacetal bond represented by the formula (5).

(A, R ¹ and R ³ are synonymous with the formula (2), and R ⁷ is synonymous with the formula (5).)
The production of the fluorine-containing monomer represented by the formula (2-2) is performed by reacting the alcohol represented by the formula (13) with the aldehyde or ketone represented by the formula (14). The process of obtaining the fluorine-containing monomer represented by these.

  Examples of the aldehyde or ketone having a hexafluoroisopropanol group represented by the formula (14) include Japanese Patent Application Laid-Open Nos. 2005-206587, 2005-213215, 2005-232095, and 2005-239710. JP-A-2015-193594 describes a production method, which can be produced in accordance therewith.

This reaction differs depending on the chemical species of the organic group R ⁷ in the aldehyde or ketone having a hexafluoroisopropanol group represented by the formula (14).

  One example is shown below.

In the case of an aldehyde in which R ⁷ is a hydrogen atom in the formula (14), it undergoes an addition reaction with an alcohol represented by the formula (13) under an acid catalyst. The amount of the aldehyde represented by the formula (14) that acts on the alcohol represented by the formula (13) is not particularly limited, but is 1 mol of the alcohol represented by the formula (13). And 0.1 mol or more and 20 mol or less, preferably 0.5 mol or more and 10 mol or less, more preferably 0.8 mol or more and 3 mol or less.

  The reaction proceeds even without solvent, but it is easier to control when it is performed in a solvent inert to the reaction. The alcohol represented by formula (13) is preferably soluble in a polar solvent and is preferably a polar solvent. Examples of such polar solvents include ester solvents, ether solvents, halogen solvents, and acetonitrile, N, N-dimethylformamide, N, N-dimethylimidazolidinone, dimethyl sulfoxide or sulfolane. Specifically, ester solvent ethyl acetate or butyl acetate, ether solvent diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran or dioxane, halogen solvent dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, Examples include tetrachloroethylene, chlorobenzene, or orthochlorobenzene, or acetonitrile, N, N-dimethylformamide, N, N-dimethylimidazolidinone, dimethyl sulfoxide, or sulfolane. These solvents may be used alone or in combination of two or more. Alcohol represented by the formula (13) is hardly dissolved, but n-hexane and n-heptane, which are nonpolar solvents, can also be used if they are used together with a polar solvent.

  The reaction temperature is preferably −78 ° C. or higher and 150 ° C. or lower, more preferably −20 ° C. or higher and 120 ° C., and particularly preferably 0 ° C. or higher and 100 ° C. or lower. The reaction is preferably carried out with stirring.

  Although the reaction time depends on the reaction temperature, it is preferably 1 minute or more and 100 hours or less, more preferably 30 minutes or more and 50 hours or less, and particularly preferably 1 hour or more and 24 hours or less. . It is preferable to use an analytical instrument such as liquid chromatography (HPLC) and set the end point of the reaction to the time when the alcohol represented by the formula (13) as the raw material is consumed.

  This reaction preferably proceeds quickly under an acid catalyst and preferably uses an acid catalyst. Specific examples of the acid catalyst include p-toluenesulfonic acid, pyrididium p-toluenesulfonate, methanesulfonic acid, trifluoromethanesulfonic acid or camphorsulfonic acid, which are organic acids, or sulfuric acid, which is an inorganic acid. . The amount of the acid catalyst used is preferably 0.01 mol or more and 10 mol or less, more preferably 0.05 mol or more and 1 mol or less, with respect to 1 mol of the alcohol represented by the formula (9). It is particularly preferably 0.1 mol or more and 0.3 mol or less.

  After completion of the reaction, the fluorine-containing monomer represented by the formula (2-2) can be obtained with high purity by extraction, distillation or column chromatography.

4). Fluoropolymer The fluoropolymer containing a repeating unit represented by the following formula (1) is obtained by radical polymerization of the double bond of the fluoromonomer represented by the above formula (2).

(In the formula, A is an organic group having an alicyclic hydrocarbon group having 3 to 25 carbon atoms or an aromatic hydrocarbon group having 5 to 25 carbon atoms, and any hydrogen atom in the organic group is a hydroxy group, carbon May be substituted with an alkoxy group having 1 to 4 carbon atoms, an acetoxy group or an alkyl group having 1 to 4 carbon atoms, and each R ¹ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; ² is each independently an acetal bond, a hemiacetal bond or a hemiacetal ester bond, R ³ is each independently an aliphatic hydrocarbon group having 1 to 15 carbon atoms, an aromatic hydrocarbon group having 5 to 15 carbon atoms, or An organic group in which a plurality of these groups are connected may be used, n is an integer of 1 to 3, and m is an integer of 1 to 3.)

  The fluorine-containing polymer containing the repeating unit represented by the formula (1) is irradiated with a high energy ray to expose the acid-decomposable group to dissociate, and the repeating unit represented by the following formula (3) Can be converted to a polymer containing

(In the formula, A and R ¹ have the same meanings as A and R ¹ in formula (1). X is a hydroxy group or carboxylic acid. M is an integer of 1 to 3)
The repeating unit represented by the formula (3) having a hydroxy group is a developer with respect to a fluoropolymer containing a repeating unit containing a hexafluoroisopropanol group in the repeating unit represented by the formula (1). The solubility with respect to a certain organic solvent falls. Therefore, a fluoropolymer containing a repeating unit having a hexafluoroisopropanol group can be used as a negative resist.

[Other repeat units]
In the present invention, the fluoropolymer may contain “other repeating units” other than the formula (1) in addition to the repeating unit represented by the formula (1). The other repeating unit refers to a repeating unit that does not correspond to the repeating unit represented by the formula (1). Moreover, the monomer which gives another repeating unit means the monomer which a double bond cleaves and forms "another repeating unit".

  As "other repeating units", olefin, fluorine-containing olefin, acrylic acid ester, methacrylic acid ester, fluorine-containing acrylic acid ester, fluorine-containing methacrylate ester, norbornene compound, fluorine-containing norbornene compound, styrene-based compound, fluorine-containing styrene-based The repeating unit formed by cleaving the double bond of a compound, vinyl ether or fluorine-containing vinyl ether can be mentioned.

  Preferably, a double bond of one or more monomers selected from acrylic ester, methacrylic ester, fluorine-containing acrylic ester, fluorine-containing methacrylate ester, norbornene compound, fluorine-containing norbornene compound, vinyl ether and fluorine-containing vinyl ether Is a repeating unit formed by cleavage.

  The fluoropolymer of the present invention may contain two or more of the above “other repeating units”.

  Particularly preferred is a repeating unit obtained by cleaving the double bond of the monomer shown below.

  When the fluorine-containing polymer is a fluorine-containing polymer containing the repeating unit represented by the formula (1) and “other repeating units”, the content of the repeating unit represented by the formula (1) is Expressed in mol% with respect to the total amount of coalescence, it is 0.1% or more and 90 mol% or less, preferably 10 mol% or more and 70 mol% or less, more preferably 15% or more and 60 mol% or less.

  When the repeating unit represented by the formula (1) is less than 0.1 mol%, when the resist is used, the high solubility and etching resistance of the fluoropolymer are hardly exhibited. Moreover, when it exceeds 90 mol%, it is difficult to obtain a fine pattern.

  When the fluoropolymer of the present invention is used as a resist, the mass average molecular weight measured by gel permeation chromatography (GPC) is preferably 1,000 or more and 1,000,000 or less, more preferably 2 , 000 or more and 500,000 or less. In preparing the resist, the fluorine-containing polymer of the present invention and other polymers may be used.

  When the weight average molecular weight is less than 1,000, the strength of the coating film is insufficient, and when it exceeds 1,000,000, the solubility in a solvent is lowered, and it becomes difficult to obtain a smooth coating film, which is not preferable. The dispersity (MW / MN) is preferably 1.01 or more and 3.00 or less, particularly preferably 1.01 or more and 2.00 or less.

  When used as a resist, if the weight average molecular weight of the fluoropolymer of the present invention is less than 1,000, acid labile groups dissociated by irradiation with high energy rays diffuse in the resist film during the heat treatment after pattern exposure. It may move and diffuse to the unexposed area, resulting in degradation of resolution. If it exceeds 1,000,000, the solubility of the fluorine-containing polymer in the organic solvent is lowered, and it becomes difficult to obtain a smooth resist film. The dispersity (MW / MN), which is the ratio of the weight average molecular weight to the number average molecular weight, is 1.01 or more and 5.00 or less, preferably 1.01 or more and 4.00 or less, and more preferably 1 0.01 or more and 3.0 or less, and particularly preferably 1.10 or more and 2.50 or less.

  “Other repeating unit” includes a part that generates an acid by irradiation with high energy rays in a chemical structure when it is used as a resist, a part that decomposes into an acid by an acid catalyst, a part that has dry etching resistance, a developer In order to adjust the resolving power, heat resistance, sensitivity, etc., which are general necessary properties of resist, the part that gives solubility to the substrate, the part that gives adhesion to the substrate, the part that improves the resist profile, and other characteristics Units "can be included.

  The site that generates acid upon irradiation with high energy rays is, for example, a site where an onium salt of sulfonic acid is dissociated to become sulfonic acid. Examples of the bond that decomposes using an acid as a catalyst include an ester bond.

  Hereinafter, each monomer will be described.

  Specific examples of olefins include ethylene and propylene. Examples of fluoroolefins include vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, and hexafluoroisobutene. Can do.

  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. Examples include acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, t-butyl acrylate, 3-oxocyclohexyl acrylate, adamantyl acrylate, alkyladamantyl acrylate, cyclohexyl acrylate, or tricyclodecanyl acrylate.

  Specific examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, and lauryl. Examples include methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, t-butyl methacrylate, 3-oxocyclohexyl methacrylate, adamantyl methacrylate, alkyladamantyl methacrylate, cyclohexyl methacrylate, or tricyclodecanyl methacrylate.

  Further, acrylate or methacrylate containing ethylene glycol group, propylene glycol group, tetramethylene glycol group, acrylonitrile group, methacrylonitrile group, alkoxysilane group-containing vinyl silane or acrylic acid or methacrylic acid ester, lactone ring or norbornene ring Examples thereof include acrylates or methacrylates having acrylic acid, acrylic acid, methacrylic acid, unsaturated amides such as acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, or diacetone acrylamide.

  Furthermore, the said acrylate compound containing (alpha) -cyano group can be illustrated, and a maleic acid, a fumaric acid, or a maleic anhydride can be illustrated.

  Examples of the fluorine-containing acrylic ester or fluorine-containing methacrylate ester include an acrylic ester or a methacrylic ester having a fluorine atom or a group having a fluorine atom at the α-position of the acrylic group. Specifically, as a monomer in which a fluorine-containing alkyl group is introduced at the α-position, a hydrogen atom at the α-position of the above-mentioned acrylic ester or methacrylic ester and a trifluoromethyl group, trifluoroethyl group or nonafluoro-n- Examples thereof include a fluorine-containing acrylic ester and a fluorine-containing methacrylate formed by substituting a butyl group.

  Moreover, the fluorine alkyl group whose group couple | bonded with the ester site | part of the above-mentioned acrylic acid ester or methacrylic acid ester is a perfluoroalkyl group or a fluoroalkyl group can be mentioned. Specifically, a monomer having a cyclic structure and fluorine at the ester site, wherein the hydrogen atom of the cyclic structure is substituted with a fluorine atom or a trifluoromethyl group. Examples thereof include acrylic acid esters or methacrylic acid esters having a cyclopentane ring, a fluorine-containing cyclohexane ring, or a fluorine cycloheptane ring.

  Moreover, ester of acrylic acid or methacrylic acid whose group couple | bonded with the ester site | part of the above-mentioned acrylic ester or methacrylic ester is a fluorine-containing t-butyl ester group can be mentioned. Specifically, 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, heptafluoroisopropyl acrylate 1,1-dihydroheptafluoro-n-butyl acrylate, 1,1,5-trihydrooctafluoro-n-pentyl acrylate, 1,1,2,2-tetrahydrotridecafluoro-n-octyl acrylate, 1,2,2-tetrahydroheptadecafluoro-n-decyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 1,1,1,3,3 3-hexafluoroisopropyl methacrylate, heptafluoroisopropylate Methacrylate, 1,1-dihydroheptafluoro-n-butyl methacrylate, 1,1,5-trihydrooctafluoron-pentyl methacrylate, 1,1,2,2-tetrahydrotridecafluoro-n-octyl methacrylate, 1, Examples include 1,2,2-tetrahydroheptadecafluoro-n-decyl methacrylate, perfluorocyclohexyl methyl acrylate or perfluorocyclohexyl methyl methacrylate.

  Norbornene compounds and fluorine-containing norbornene compounds are allyl alcohol, fluorine-containing allyl alcohol, acrylic acid, α-fluoroacrylic acid, methacrylic acid, the above-mentioned acrylic ester or methacrylic ester, fluorine-containing acrylic ester or fluorine-containing methacrylate ester. And norbornene compounds obtained by Diels-Alder addition reaction with cyclopentadiene or cyclohexadiene.

  In addition, examples of the monomer that gives the “other repeating unit” copolymerizable with the fluorine-containing monomer represented by the formula (2) include styrene compounds, fluorine-containing styrene compounds, vinyl ether compounds, and fluorine-containing vinyl ethers. Examples of the compound include an allyl compound, an allyl ether compound, a vinyl ester compound, and a vinyl silane compound.

  Specific examples of styrene compounds and fluorine-containing styrene compounds include styrene, fluorinated styrene, hydroxystyrene, styrene compounds to which hexafluoroacetone has been added, styrene or hydroxystyrene having a trifluoromethyl group substituted for a hydrogen atom. Examples of the styrene or fluorine-containing styrene compound in which a halogen, an alkyl group, or a fluorine-containing alkyl group is bonded to the α-position can be given.

  Examples of the vinyl ether compound or the fluorine-containing vinyl ether compound include an alkyl vinyl ether compound having a methyl group or an ethyl group as an alkyl group, a hydroxyethyl group or a hydroxybutyl group as a hydroxyalkyl group, and part or all of the hydrogen atoms thereof. And vinyl ether compounds or fluorine-containing vinyl ether compounds in which is substituted with a fluorine atom.

  Cyclic vinyl ether compounds include cyclohexyl vinyl ether, cyclic vinyl ether compounds having a hydrogen atom or carbonyl bond in the cyclic structure, and some or all of the hydrogen atoms of these cyclic vinyl ether compounds are substituted with fluorine atoms. It was. Examples thereof include cyclic vinyl ether compounds.

5. Polymerization of fluorinated polymer The polymerization method of the fluorinated polymer containing the repeating unit represented by the formula (1) of the present invention is not particularly limited as long as it is a generally used method. Radical polymerization and ionic polymerization are preferred, and in some cases, coordination anion polymerization, living anion polymerization, cation polymerization, ring-opening metathesis polymerization, vinylene polymerization, vinyl addition, and the like can be used.

  As a preferred specific example, a method by radical polymerization will be described.

  In order to obtain a fluoropolymer containing a repeating unit represented by the formula (1) of the present invention, homopolymerization of a fluoromonomer represented by the formula (2) or represented by the formula (2) Radical polymerization of a fluorine-containing monomer and a monomer that gives the above-mentioned “other repeating unit” is carried out by bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization in the presence of a radical polymerization initiator or radical initiator. , Batchwise, semi-continuous or continuous.

  Examples of the radical polymerization initiator include azo compounds, peroxide compounds, and redox compounds. Specifically, azobisisobutyronitrile, dimethyl 2,2-azobis (2-methylpropionate), tert-butyl peroxypivalate, di-tert-butyl peroxide, i-butyryl peroxide, lauroyl Examples include peroxide, succinic acid peroxide, dicinnamyl peroxide, di-n-propyl peroxydicarbonate, tert-butylperoxyallyl monocarbonate, benzoyl peroxide, hydrogen peroxide, and ammonium persulfate.

  The reaction vessel used for the polymerization reaction is not required to be immersed in the reaction system, a polymerization solvent can be used, and one that does not inhibit radical polymerization is preferable. Examples of the polymerization solvent include ester solvents, ketone solvents, hydrocarbon solvents, alcohol solvents, water, ether solvents, cyclic ether solvents, chlorofluorocarbon solvents, and aromatic compound solvents.

  Specifically, ester solvent ethyl acetate or n-butyl acetate, ketone solvent acetone or methyl isobutyl ketone, hydrocarbon solvent toluene or cyclohexane, alcohol methanol, isopropyl alcohol or ethylene glycol monomethyl Ethers can be exemplified. Moreover, water, an ether solvent, a cyclic ether solvent, a chlorofluorocarbon solvent, and an aromatic compound solvent can be exemplified. These solvents may be used alone or in combination of two or more, and a molecular weight modifier such as mercaptan may be used in combination.

  The reaction temperature of the polymerization reaction can be appropriately selected depending on the radical polymerization initiator or the radical polymerization initiator, and is preferably 20 ° C. or higher and 200 ° C. or lower, more preferably 30 ° C. or higher and 140 ° C. or lower.

  As a method for removing the organic solvent or water from the obtained fluoropolymer solution or dispersion, reprecipitation, filtration, and heating distillation under reduced pressure can be used.

6). Chemically amplified resist The fluorine-containing polymer containing the repeating unit represented by formula (1) can be made into a chemically amplified resist by preparing a solution of a fluorine-containing polymer appropriately added with a solvent and a photoacid generator and the like. . The fluorine-containing polymer is exposed by irradiation with high energy rays and dissociates the acid labile group of the repeating unit by the action of an acid generated from the photoacid generator.

  A fluorine-containing polymer that has an adhesive group that provides adhesion to the substrate when it is used as a resist film, and that includes a group that improves the solubility in an organic solvent during development together with other repeating units. In addition, it can be used alone as a chemically amplified resist without adding a polymer containing a repeating unit having an acid labile group or an adhesive group.

  Moreover, it can be set as the solution which added other components other than the solvent and the photo-acid generator to the fluoropolymer containing the repeating unit represented by Formula (1), and can be used as a chemically amplified resist. As other ingredients, additional polymers, quenchers, dissolution inhibitors, plasticizers, stabilizers, colorants, surfactants, thickeners, leveling agents, antifoaming agents, compatibilizers, adhesion agents, or oxidation An inhibitor may be mentioned. The following other components will be described.

[Additional polymer]
The “additional polymer” is used to adjust the properties of the chemically amplified resist, and may be dissolved in the organic solvent and compatible with the other components contained in the resist. It is additionally used when a fluoropolymer containing a repeating unit represented by That is, the “additional polymer” is a polymer other than the fluoropolymer containing the repeating unit represented by the formula (1). “Additional polymers” act as adhesion agents, plasticizers, stabilizers, thickeners, leveling agents, antifoaming agents or compatibilizers.

In addition, when immersion exposure is performed in which pure water is used for exposure between the lens and the wafer, the lens composition acts to increase the water repellency of the resist composition.
The “additional polymer” may be added in the range of 0.1% by mass or more and 30% by mass or less with respect to the total amount of the fluoropolymer containing the repeating unit represented by the formula (1).

[solvent]
When the chemically amplified resist of the present invention is applied to a substrate to form a resist film, it is preferable to apply the polymer by dissolving it in an organic solvent, followed by baking and drying.

  As the organic solvent, it is sufficient that the fluorine-containing polymer is soluble, such as a ketone solvent, a polyhydric alcohol solvent, a cyclic ether solvent, an ester solvent, an aromatic solvent, a fluorine solvent, a petroleum naphtha solvent, Or a paraffinic solvent can be mentioned.

  Specifically, acetone-based solvents such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone or 2-heptanone, and polyhydric alcohol solvents such as ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol mono Acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate (PGMEA); monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof of dipropylene glycol or dipropylene glycol monoacetate, cyclic ether Dioxane, an ester solvent, and ester solvent Methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate or ethyl ethoxypropionate, aromatic solvent xylene or toluene, fluorocarbon solvent freon, Alternative chlorofluorocarbons, perfluoro compounds, hexafluoroisopropyl alcohol, or terpene-based petroleum naphtha solvents or paraffin solvents that are high-boiling weak solvents for the purpose of improving coatability can be exemplified. These organic solvents may be used alone or in combination of two or more.

  In the chemically amplified resist of the present invention, the organic solvent used in this case is, in particular, esters such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate or Preference is given to using ethyl ethoxypropionate.

  The usage-amount of an organic solvent is 100 to 10,000 mass parts with respect to all the polymers in a chemically amplified polymer. More preferably, they are 200 mass parts or more and 3,000 mass parts or less, Most preferably, they are 300 mass parts or more and 1,000 mass parts or less.

[Photoacid generator]
A photoacid generator is used in the chemically amplified resist of the present invention. Specific examples include bissulfonyldiazomethane, nitrobenzyl derivatives, onium salts, halogen-containing triazine compounds, cyano group-containing oxime sulfonate compounds, and other oxime sulfonate compounds. These photoacid generators may be used alone or in combination of two or more. The content is preferably 0.5 parts by mass or less and 20 parts by mass or more with respect to 100 parts by mass of the resist solution. When the amount is less than 0.5 parts by mass, it is difficult to obtain a high-definition resist pattern.

[Additive]
A basic compound may be added to the chemically amplified resist of the present invention in order to improve the resist pattern shape and improve the temporal stability in patterning after a lapse of time after coating the resist film. Examples of basic compounds include nitrogen-containing compounds. Specific examples include primary to tertiary aliphatic amines, aromatic amines, heterocyclic amines, compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, or amide derivatives. . Preferred are secondary aliphatic amines, tertiary aliphatic amines, aromatic amines, heterocyclic amines, and alcoholic nitrogen-containing compounds. Particularly preferred are alcohol amines and trialkylamines. Specifically, it is triethanolamine or triisopropanolamine.

The basic compound component is preferably used in a range of 0.01 parts by weight or more and 5 parts by weight or less, based on 100 parts by weight of the total resist solid content excluding the solvent. The compounds will be described individually.
<Aliphatic amine>
Examples of the aliphatic amine include alkyl amines or alkyl alcohol amines in which at least one hydrogen atom of ammonia (NH ₃ ) is substituted with an alkyl group having 12 or less carbon atoms or a hydroxyalkyl group. Specifically, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine or n-decylamine, which are monoalkylamines, diethylamine, di-n-propylamine, di-n-, which are dialkylamines Heptylamine, di-n-octylamine or dicyclohexylamine, trialkylamine trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri N-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine or tri-n-dodecylamine, or alkyl alcohol amines such as diethanolamine, triethanolamine, diisopropano Triethanolamine, triisopropanolamine, di -n- octanol amine or tri -n- octanol amine can be exemplified.

Among these aliphatic amines, an alcohol amine or a trialkylamine is preferable, and an alkyl alcohol amine is more preferable. In particular, triethanolamine or triisopropanolamine which is an alkyl alcohol amine.
<Other basic compounds>
As other basic compounds other than aliphatic amines, cyclic amines may be used. Specifically, aniline or aniline derivatives such as N-methylaniline, N-ethylaniline, N-propylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline, propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline 2,6-dinitroaniline, 3,5-dinitroaniline or N, N-dimethyltoluidine, 1,5-diazabicyclo [4.3.0] non-5-ene which is a heterocyclic amine, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,4-diazabicyclo [2.2.2] octa 4-dimethylaminopyridine, hexamethylenetetramine, 4,4-dimethylimidazoline, hindered amine bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebagate, or alcoholic nitrogen-containing compound 2 -Hydroxypyridine, aminocresol, 2,4-quinolinediol, 3-indolemethanol hydrate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N, N-diethylethanolamine, triisopropanolamine, 2, 2'-iminodiethanol, 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, 4- (2-hydroxyethyl) morpholine, 2- (2-hydroxyethyl) pyridine, 1- ( - hydroxyethyl) piperazine or 1- [2- (2-hydroxyethoxy) ethyl] piperazine can be exemplified. These basic compounds may be used alone or in combination of two or more.

[Surfactant]
The chemically amplified resist of the present invention can contain a surfactant, preferably a fluorine-based or silicon-based surfactant. By containing these surfactants, a high-definition resist pattern with less adhesion and development defects can be obtained when using an exposure light source of 250 nm or less, particularly 220 nm or less. The addition amount of the surfactant in the chemically amplified resist of the present invention is preferably in the range of 0.01 parts by mass or more and 5 parts by mass or less, based on 100 parts by mass of the total solid content of the resist.

7). Pattern Forming Method The pattern forming method of the present invention comprises a step (A) of applying a resist composition on a substrate and a step of exposing with a high energy ray that is an electromagnetic wave having a wavelength of 300 nm or less through a photomask after heat treatment (B ) And a step (C) of developing with a developer without heat treatment or after heat treatment.

  By using the chemically amplified resist of the present invention, patterning can be performed according to a pattern formation method by a general photolithography method. As a specific example, a chemically amplified resist of the present invention is spin-coated on a silicon wafer as a substrate with a spinner and dried to form a resist film, and a high energy beam or an electron beam is applied to this from an exposure apparatus. Irradiate through a photomask. Next, this is subjected to a development process in which an unexposed portion is dissolved and removed using a developer, for example, an organic solvent such as butyl acetate, to obtain a resist pattern on which a mask pattern of a photomask is faithfully transferred on a silicon wafer. Can do.

[High energy line]
The high energy rays used in the pattern forming method of the present invention are not particularly limited. For example, as a light source, an ArF excimer laser (oscillation wavelength 193 nm) laser light or a KrF excimer laser (oscillation wavelength 248 nm) which is an exposure apparatus provided with a source of high energy rays of 380 nm or less can be used. Moreover, the pattern formation method of the present invention using the chemically amplified resist of the present invention is sensitive to soft X-ray light having a wavelength of 10 nm or more and 14 nm or less, and a high-definition resist pattern can be obtained. It also has sensitivity to an electron beam that is a flow of electrons in a certain direction.

[Immersion lithography method]
Since the pattern formation method of the present invention uses the chemically amplified resist of the present invention, it is advantageous in a numerical aperture or effective wavelength by using a medium with a low absorption of high energy rays used for water or a fluorine-based solvent in a part of the optical path. Therefore, it is effective for an immersion lithography method using an immersion exposure apparatus that enables more efficient fine processing.

  Further, in the pattern forming method, the step (B) is a step (B) by an immersion lithography method in which the high energy ray uses a laser beam having a wavelength of 193 nm by an ArF excimer laser or a wavelength 248 nm by a KrF excimer laser. The pattern forming method is preferable.

[Developer]
An organic solvent is used for the developer used in the pattern forming method of the present invention.

  As the organic solvent to be used, it is sufficient that the resist component containing the fluoropolymer containing the repeating unit represented by the formula (1) is soluble, such as a ketone solvent, a polyhydric alcohol solvent, a chain ether solvent. And cyclic ether solvents, ester solvents, aromatic solvents, fluorine solvents, terpene petroleum naphtha solvents, and paraffin solvents. Specifically, acetone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl isoamyl ketone, 2-pentanone, 2-hexanone or 2-heptanone, polyhydric alcohol solvents ethylene glycol, ethylene glycol monoacetate , Diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate (PGMEA), monomethyl ether of dipropylene glycol or dipropylene glycol monoacetate, monoethyl ether, monopropyl ether, Monobutyl ether or monophenyl ether and its derivatives Diisopropyl ether, di n-butyl ether, di i-butyl ether, di n-pentyl ether, di i-pentyl ether, diphenyl ether, cyclic ether dioxane, ester solvent methyl lactate, lactic acid Ethyl, methyl acetate, ethyl acetate, n-butyl acetate, i-butyl acetate, n-pentyl acetate, i-pentyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate or ethyl ethoxypropionate, aromatic solvents Examples include xylene, toluene or anisole, fluorocarbons such as chlorofluorocarbon, alternative chlorofluorocarbons, perfluoro compounds or hexafluoroisopropyl alcohol, terpene petroleum naphtha solvents, or paraffin solvents. These may be used alone or in combination of two or more.

  The following examples specifically show embodiments of the fluorine-containing monomer and the fluorine-containing polymer of the present invention, a chemically amplified resist using the same, and a pattern forming method thereof. However, embodiments of the present invention are not limited to these.

1. Synthesis Examples of Precursors of Fluorinated Monomers of the Present Invention First, Synthesis Examples 1 to 11 of precursors containing hexafluoroisopropanol groups for obtaining the fluorinated monomers of the present invention are shown.

[Precursor Synthesis Example 1]
4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl vinyl ether, which is a precursor containing a hexafluoroisopropanol group for obtaining the fluorine-containing monomer of the present invention, was synthesized. The structural formula is shown below.

  Into a flask having an internal volume of 1 L, 22.7 g of 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-1-butanol having a purity of 99% by mass and 165.3 g of ethyl vinyl ether were placed at room temperature (about 23 ° C. , The same below). Further, 1.3 g of palladium (II) acetate as a catalyst and 1.1 g of ligand 2,2'-bipyridine were added, and the mixture was stirred at room temperature for 5 hours to obtain a reaction solution.

  As a result of gas chromatographic analysis of the reaction solution, it was found that the conversion rate to 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl vinyl ether as a target product was 93%, and the selectivity was 87%. Met. Subsequently, 50 g of water was added to the reaction solution, stirred for 10 minutes, filtered to remove the catalyst residue, and the filtrate was transferred to a separatory funnel. The water of the separated organic layer was removed with magnesium sulfate and then filtered. Then, 13.6 g of 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl vinyl ether was obtained as a colorless liquid by distillation under reduced pressure at a temperature of 55 ° C. to 58 ° C. under a pressure of 1.0 kPa. Obtained with a purity of 98%.

The analysis result by nuclear magnetic resonance spectrum (NMR) of the obtained 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl vinyl ether is shown below.
¹ H NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 6.45 (dd, J = 14.4 Hz, 6.8 Hz, 1H), 4.70 (s, 1H), 4. 32 (dd, J = 14.4 Hz, 2.8 Hz, 1H), 4.21 (dd, J = 6.8 Hz, 2.8 Hz, 1H), 4.09 (t, J = 5.6 Hz, 2H) , 2.39 (t, J = 5.6 Hz, 2H), ¹⁹ F NMR (measurement solvent: deuterated chloroform, reference material: trichlorofluoromethane); δ = −77.90 (s, 6F).

[Precursor Synthesis Example 2]
1,1,1-trifluoro-2-hydroxy-6-methyl-2-trifluoromethylheptan-4-yl, which is a precursor containing a hexafluoroisopropanol group for obtaining the fluorine-containing monomer of the present invention Vinyl ether was synthesized. The structural formula is shown below.

  Into a flask having an internal volume of 1 L, 30.5 g of 1,1,1-trifluoro-2-hydroxy-6-methyl-2-trifluoromethylheptan-4-ol having a purity of 99% by mass and 165.3 g of ethyl vinyl ether were placed at room temperature. Was stirred at. Further, 1.3 g of palladium (II) acetate and 1.1 g of 2,2′-bipyridine were added, followed by stirring at room temperature for 10 hours to obtain a reaction solution.

  When the gas chromatographic analysis of the reaction solution was performed, the conversion rate to 1,1,1-trifluoro-2-hydroxy-6-methyl-2-trifluoromethylheptan-4-yl vinyl ether was 83%, The selectivity was 80%. Subsequently, 50 g of water was added, stirred for 10 minutes, filtered to remove catalyst residues, and the resulting filtrate was transferred to a separatory funnel. The separated organic layer was filtered with magnesium sulfate and filtered. Then, 1,1,1-trifluoro-2-hydroxy-6-methyl-2-trifluoromethylheptane-4-4 as a colorless liquid was distilled under reduced pressure at a temperature of 65 ° C. to 67 ° C. and a pressure of 1.0 kPa. 15.1 g of ilvinyl ether was obtained with a purity of 97%.

The analysis results by NMR of the obtained 1,1,1-trifluoro-2-hydroxy-6-methyl-2-trifluoromethylheptan-4-yl vinyl ether are shown below.
¹ H NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 6.
46 (dd, J = 14.4 Hz, 6.8 Hz, 1H), 4.71 (s, 1H), 4.31 (m, 1H), 4.22 (dd, J = 6.8 Hz, 2.8 Hz) , 1H), 4.09 (dd, J = 10.0 Hz, 3.6 Hz, 1H), 2.32 (dd, J = 16.4 Hz, 4.4 Hz, 1H), 2.29 (d, J = 16.4 Hz, 1 H), 1.90 (m, 1 H), 1.73 (m, 1 H), 1.40 (m, 1 H), 0.96 (d, J = 6.8 Hz, 3 H), 0 .90 (d, J = 6.8 Hz, 3H), ¹⁹ F NMR (measurement solvent: deuterated chloroform, reference material: trichlorofluoromethane); δ = −76.81 (q, J = 9.6 Hz, 3F), -79.53 (q, J = 9.6 Hz, 3F).

[Precursor Synthesis Examples 3 to 8]
Synthesis was performed in the same manner as in Synthesis Examples 1 and 2 of the precursor, and precursors having the structural formulas and purity shown in Synthesis Examples 3 to 8 in Table 1 were obtained.

[Precursor Synthesis Example 9]
4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyraldehyde, a precursor containing a hexafluoroisopropanol group for obtaining the fluorine-containing monomer of the present invention, was synthesized. The structural formula is shown below.

  In a 1 L autoclave equipped with a thermometer and a stirring blade, 128.6 g (1.63 mol) of pyridine was charged and sealed, and 1,1,1,3,3,3-hexafluoroacetone 177. 3 g (1.07 mol) was added. The internal temperature was raised to 70 ° C., and a mixed solution of 49.4 g (1.12 mol) of acetaldehyde and 266 g of diisopropyl ether was gradually injected over 5 hours. After 15 hours, the atmosphere was released to obtain 617 g of a reaction solution. Subsequently, the reaction solution was transferred to a separatory funnel, washed with 150 ml of 12N aqueous hydrochloric acid and shaken. The separated organic layer was washed three times with 170 ml of water each time, and separated into 490 g of an organic layer. Got. Thereafter, a hydrochloric acid aqueous solution recovered after washing and an aqueous layer recovered were added, and extraction was performed three times using 130 g of diisopropyl ether. 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyraldehyde was obtained as 910 g of a 46% by mass diisopropyl ether solution.

  The results of NMR analysis of the obtained 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyraldehyde are shown below.

¹ H NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 9.
81 (s, 1H), 6.12 (s, 1H), 5.77 (s, 1H), 4.65 (m, 1H), 4.26 (s, 2H), 4.18 (m, 2H) ), 3.23 (m, 1H), 2.75 (m, 2H), 2.05 (s, 3H), 1.93 (m, 10H). ¹⁹ F NMR (measurement solvent: deuterated chloroform, reference material: trichlorofluoromethane); δ = −73.45 (q, J = 9.0 Hz, 3F), −73.83 (q, J = 9.0 Hz, 3F) ), -112.9 (s, 2F), -118.8 (s, 2F).

2. Synthesis of fluorinated monomer of the present invention [Synthesis example 1 of fluorinated monomer]
3- [1- (4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl) -butoxy-1-methyl] methoxy-1-methacryloyloxyadamantane (the fluorine-containing monomer of the present invention) Hereinafter, it may be referred to as M-1). The structural formula is shown below.

  A flask having an internal volume of 100 mL equipped with a dropping funnel was charged with 2.1 g of 3-hydroxy-1-methacryloyloxyadamantane, 0.1 g of pyrudium paratoluenesulfonate, and 6.2 g of dehydrated tetrahydrofuran. At room temperature, 4.0 g of 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl vinyl ether having a purity of 98% obtained in Synthesis Example 1 of the precursor was dropped into the solution from the dropping funnel. Thereafter, the mixture was stirred and reacted for 4 hours to obtain a reaction solution.

  When the high performance liquid chromatographic analysis of the reaction solution was performed, the target product was compared with the theoretical value calculated from the amount of 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl vinyl ether used as a raw material. Conversion to certain 3- [1- (4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl) -butoxy-1-methyl] methoxy-1-methacryloyloxyadamantane is 68%, selectivity Was 53%. Subsequently, 10 g of a saturated aqueous sodium hydrogen carbonate solution was added to adjust the pH of the reaction solution to 8, and 20 g of normal hexane was added to wash the resulting organic layer twice with 10 g of water and once with 10 g of saturated brine, The organic layer was filtered with magnesium sulfate and then filtered. Thereafter, the organic solvent is distilled off by concentration under reduced pressure, and the residue is purified by column chromatography using hexane: ethyl acetate = 10: 1 as a developing solvent to give 3- [1- (4,4,4) as a colorless liquid. 2.2 g of 4-trifluoro-3-hydroxy-3-trifluoromethyl) -butoxy-1-methyl] methoxy-1-methacryloyloxyadamantane were obtained with a purity of 97%.

  The NMR analysis results of the obtained 3- [1- (4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl) -butoxy-1-methyl] methoxy-1-methacryloyloxyadamantane are shown below. Show.

¹ H NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 6.
00 (s, 1H), 5.68 (s, 1H), 5.49 (s, 1H), 5.09 (q, J = 5.6 Hz, 1H), 3.93 (m, 1H), 3 .83 (m, 1H), 2.35 (s, 2H), 2.29 (t, J = 5.6 Hz, 2H), 2.18 (s, 2H), 2.11 (d, J = 11 .6 Hz, 2H), 2.04 (d, J = 11.6 Hz, 2H), 1.88 (s, 3H), 1.75 (m, 4H), 1.55 (m, 2H), 1. 30 (d, J = 5.6 Hz, 3H). ¹⁹ F NMR (measurement solvent: deuterated chloroform, reference material: trichlorofluoromethane); δ = −77.82 (s, 3F), −78.03 (s, 3F).
[Synthesis Examples 2 to 11 of fluorinated monomer]
As described above, in “Synthesis example 1 of fluorine-containing monomer”, the precursor 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl obtained in “Synthesis example 1 of precursor” was used. Vinyl ether was used.

  Using the precursors obtained in “Precursor Synthesis Examples 2 to 9” in the same manner as in “Fluoromonomer Synthesis Example 1”, the synthesis of fluorine-containing monomers having the abbreviations M-2 to 11 shown in Table 2 Went.

  Specifically, in Synthesis Example 2, 3-hydroxy-5-methoxy-1-methacryloyloxyadamantane was used instead of 3-hydroxy-1-methacryloyloxyadamantane. Similarly, instead of 3-hydroxy-1-methacryloyloxyadamantane, 3,5-dihydroxy-1-methacryloyloxyadamantane was synthesized in Synthesis Example 3, acetoxy-3-hydroxy-1-methacryloyloxyadamantane was synthesized in Synthesis Example 4, and Synthesis Example In Example 5, 3-hydroxy-5-methyl-1-methacryloyloxyadamantane was used, and in Synthesis Example 7, 4-hydroxy-1-methacryloyloxybenzene was used.

  In Synthesis Example 10, 3-carboxy-1-methacryloyloxyadamantane and the precursor 4,4,4-trifluoro-3-hydroxy-3-trifluoromethyl-butyl vinyl ether obtained in Synthesis Example 1 of the precursor were used. It was.

  In Synthesis Example 11, the precursor 4,4,4-trifluoro- obtained in Synthesis Example 1 of 3,5-dihydroxy-1-methacryloyloxyadamantane and precursor instead of 3-hydroxy-1-methacryloyloxyadamantane 3-Hydroxy-3-trifluoromethyl-butyl vinyl ether was used.

  Tables 2 and 3 show the structural formulas and purity of the fluorine-containing monomers M-2 to M-11.

[Monomer Comparative Example 1]
3- (1-butoxy-1-methyl) methoxy-1-methacryloyloxyadamantane (hereinafter sometimes referred to as M′-1) was synthesized. The structural formula is shown below. 3- (1-Butoxy-1-methyl) methoxy-1-methacryloyloxyadamantane does not have a hexafluoroisopropanol group.

  To a 300-mL flask equipped with a dropping funnel, 10.0 g of 3-hydroxy-1-methacryloyloxyadamantane, 0.3 g of pyrudium paratoluenesulfonate, and 30.0 g of 2-butanone were added and stirred. At room temperature, 7.7 g of normal butyl vinyl ether (manufactured by Aldrich) was added dropwise from the dropping funnel to the solution, and the mixture was stirred for 1 hour to react to obtain a reaction solution.

When the reaction solution was analyzed by high performance liquid chromatography, 3- (1-butoxy-1-methyl) methoxy-1-methacryloyloxyadamantane, which was the target product calculated from 3-hydroxy-1-methacryloyloxyadamantane, which was the raw material, was obtained. The conversion rate was 98% and the selectivity was 85%. Subsequently, 30 g of a saturated aqueous sodium hydrogen carbonate solution was added to adjust the pH of the reaction solution to 8, and 50 g of normal hexane was added to wash the resulting organic layer twice with 30 g of water and once with 30 g of saturated brine, After removing water with magnesium sulfate in the organic layer, it was filtered. Thereafter, the organic solvent is distilled off by concentration under reduced pressure, and the residue is purified by column chromatography using hexane: ethyl acetate = 10: 1 as a developing solvent to give 3- (1-butoxy-1- 14.2 g (methyl) methoxy-1-methacryloyloxyadamantane (hereinafter sometimes referred to as M′-1) was obtained with a purity of 97%. The analysis result by NMR of the obtained 3- (1-butoxy-1-methyl) methoxy-1-methacryloyloxyadamantane is shown below.
¹ H NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 6.
01 (s, 1H), 5.48 (s, 1H), 5.01 (q, J = 5.6 Hz, 1H), 3.48 (m, 1H), 3.40 (m, 1H), 2 .34 (s, 2H), 2.19 (s, 2H), 2.15 (d, J = 11.6 Hz, 2H), 2.03 (d, J = 11.6 Hz, 2H), 1.89 (S, 3H), 1.77 (m, 4H), 1.53 (m, 4H), 1.38 (m, 2H), 1.28 (d, J = 5.6 Hz, 3H),. 91 (d, J = 7.2 Hz, 3H).

[Comparative Example 2 for Monomer]
3- (2,2,2-trifluoroethoxy-1-methyl) methoxy-1-methacryloyloxyadamantane (hereinafter sometimes referred to as M′-2) was synthesized. 3- (2,2,2-trifluoroethoxy-1-methyl) methoxy-1-methacryloyloxyadamantane having the structural formula below does not have a hexafluoroisopropanol group.

  Synthesis was performed in the same manner as in Comparative Example 1 except that 2,2,2-trifluoroethyl vinyl ether was used instead of the normal butyl vinyl ether, and 3- (2,2,2-trifluoroethoxy- 10.2 g of 1-methyl) methoxy-1-methacryloyloxyadamantane (hereinafter sometimes referred to as M′-2) was obtained with a purity of 95%.

  The analysis result by NMR of the obtained 3- (2,2,2-trifluoroethoxy-1-methyl) methoxy-1-methacryloyloxyadamantane is shown below.

¹ H NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 6.
00 (s, 1H), 5.47 (s, 1H), 5.00 (q, J = 5.6 Hz, 1H), 4.01 (m, 1H), 3.93 (m, 1H), 2 .33 (s, 2H), 2.18 (s, 2H), 2.14 (d, J = 11.6 Hz, 2H), 2.01 (d, J = 11.6 Hz, 2H), 1.90 (S, 3H), 1.76 (m, 4H), 1.55 (m, 2H), 1.27 (d, J = 5.6 Hz, 3H). ¹⁹ F NMR (measurement solvent: deuterated chloroform, reference material: trichlorofluoromethane); δ = −65.10 (t, J = 12.8 Hz, 3F).

3. Polymer Fluorinated monomers M-1 to M-11 having hexafluoroisopropanol groups synthesized in "Synthesis Examples 1 to 11 of fluorinated monomers" and hexafluoroisopropanol groups synthesized in Comparative Examples 1 and 2 The structural formulas of monomers A-1 to A-2, B-1 to B-7, and C-1 to C-3 that are copolymerized with M′-1 to M′-2 that do not have the following are shown below.

[Polymerization Example 1 of Fluoropolymer of the Present Invention]
From the “fluorinated monomer M-1” and “other monomer A-1” obtained in “Synthesis Example 1 of fluorinated monomer” having the following structural formula, Compound P-1 "was synthesized.

  A monomer prepared by dissolving 9.0 g (55 mol%) of “fluorinated monomer M-1” and 3.5 g (45 mol%) of “other monomer A-1” in 20.6 g of 2-butanone. Solution was obtained. Next, 0.6 g of dimethyl 2,2′-azobis (2-methylpropionate) as a polymerization initiator was dissolved in 5.5 g of 2-butanone to obtain an initiator solution.

  Into a 200 ml three-necked flask, 11.4 g of 2-butanone was charged, and the atmosphere was replaced with nitrogen for 30 minutes. The solution was gradually added dropwise over 5 hours and then stirred for 3 hours to obtain a polymerization solution. After cooling the polymerization solution to 25 ° C. using a water bath, 300 g of heptane was added, and the precipitated white powder was collected by filtration.

100 g of heptane was added to each of the collected white powders to form a slurry, followed by filtration twice and then drying at 50 ° C. for 17 hours to obtain 10.4 g of a polymer white powder. The weight average molecular weight (MW) of the polymer measured by GPC was 8,700. ^When measured by ¹³ C-NMR, the content ratio of the repeating unit derived from “fluorinated monomer M-1” to the repeating unit derived from “other monomer A-1” is expressed in mol%, and is 51.7. : 48.3.
[Polymerization Example 2 of Fluoropolymer of the Present Invention]
From the “fluorinated monomer M-2” and “other monomer A-2” obtained in “Synthesis Example 2 of fluorinated monomer” having the following structural formula, Combined P-2 "was synthesized.

  A monomer obtained by dissolving 9.0 g (55 mol%) of “fluorinated monomer M-2” and 1.8 g (45 mol%) of “other monomer A-2” in 17.8 g of 2-butanone. Solution was obtained. Next, 0.4 g of dimethyl 2,2′-azobis (2-methylpropionate) was dissolved in 4.8 g of 2-butanone to obtain an initiator solution.

  9.8 g of 2-butanone was charged into a three-necked flask with a capacity of 200 ml, and the atmosphere was purged with nitrogen for 30 minutes. It was dripped gradually over the time. Thereafter, the mixture was stirred for 6 hours to obtain a polymerization solution. After cooling the polymerization solution to 25 ° C. using a water bath, 300 g of heptane was added, and the precipitated white powder was collected by filtration.

100 g of heptane was added to each of the collected white powders to form a slurry, followed by filtration twice and then drying at 50 ° C. for 17 hours to obtain 8.4 g of a polymer white powder. The weight average molecular weight (MW) of the polymer measured by GPC was 9,200. The content ratio of the repeating unit derived from “fluorinated monomer M-2” and the repeating unit derived from “other monomer A-2” measured by ¹³ C-NMR is expressed in mol%. 1: 48.9.

[Polymerization Examples 3 to 28 of Fluoropolymer of the Present Invention]
In the same manner as in “Polymerization Examples 1 and 2 of Fluoropolymer of the Present Invention”, polymerizations 3 to 28 were carried out at the charging ratios of the fluorinated monomers shown in Table 4, respectively. P-28 "was obtained. Further, Table 3 shows the mass average molecular weight (Mw) by GPC measurement of “fluorinated polymers P-3 to P-28” and the mol% of the monomer-derived repeating unit by ¹³ C-NMR.

[Comparative Polymer Polymerization Examples 1 to 14]
As shown in Table 5, “monomer M′-1 and M′-2”, which is monomer 1 having no hexafluoroisopropanol group obtained in “Comparative Examples 1-2 of monomers”, Using other monomers M2-4, in the same manner as in the above "Polymerization Examples 1 and 2 of Fluoropolymer of the Present Invention", polymerizations 3 to 10 were carried out at the charging ratio of the fluorinated monomer shown in Table 4. And “Comparative Polymers P′-1 to P′-14” were obtained. Table 5 shows the mass average molecular weight (Mw) by GPC measurement of “Comparative Polymers P′-1 to P′-14” and the mol% of the monomer-derived repeating units by ¹³ C-NMR. .

4). Table 5 shows the solubility of the obtained “fluorinated polymers P-1 to P-11 of the present invention” and “comparative polymers P′-1 to P′-4” in butyl acetate.

  Solubility was measured by adding P-1 to P-11 and P'-1 to P'-4 in 100 g of butyl acetate at room temperature, allowing to stand, filtering after 10 minutes, and measuring the mass of the dissolved polymer. It is.

  As shown in Table 6, the “fluorinated polymers P-1 to 11 of the present invention” having a hexafluoroisopropanol group are compared with “comparative polymers P′-1 to 4” having no hexafluoroisopropanol group. Excellent solubility in butyl acetate.

4). Resist Examples 1-28
<Preparation of chemically amplified resist of the present invention>
The obtained “Preparation Examples P-1 to P-28 of Fluoropolymer of the Present Invention” were added to a solvent, a basic compound as an additive, and a nonafluorobutanesulfonic acid triphenylsulfonium salt as a photoacid generator ( Hereinafter, it may be referred to as PAG-1), and resists were prepared so as to have the compositions shown in Examples 1 to 28 shown in Table 7. Each resist was filtered through a 0.2 μm membrane filter after preparation.

<Solvent, basic compound, photoacid generator>
The solvents and basic compounds used in Examples 1 to 28 are as shown in Table 8.

  The structural formula of 2- (adamantane-1-carbonyloxy) -1,1-difluoro-ethanesulfonic acid triphenylsulfonium salt (PAG-1), which is a photoacid generator, is shown below.

<Formation and evaluation of pattern>
The resist obtained in Examples 1 to 28 was spin-coated on a silicon wafer on which a silicon oxide film was formed to obtain a resist film having a thickness of about 250 nm. After pre-baking at 110 ° C., exposure was performed by irradiating UV light having a wavelength of 248 nm through a photomask, and then post-exposure baking was performed at 120 ° C. Then, using butyl acetate as a developing solution, development was performed at room temperature for 1 minute to obtain a resist pattern to which a photomask pattern was transferred. When observed with an electron microscope, a rectangular pattern shape in which a high-definition pattern of a photomask was transferred with high resolution was obtained in all resist patterns, and no pattern defects were found as shown in Table 6 above.
<Dry etching>
Next, dry etching of the silicon oxide film of the silicon wafer on which the resist pattern is formed is performed in a plasma apparatus under conditions of a CF ₄ flow rate of 15 sccm, an Ar flow rate of 40 sccm, a pressure of 15 mTorr, an applied power of 130 W, and a wafer stage temperature of 25 ° C. It was. As a result of observation under an electron microscope, a high-resolution pattern shape was obtained in the silicon oxide film, and no defects such as pattern loss due to etching of the resist were observed.

Comparative Examples 1-14
<Preparation of resist>
The same as that used in Examples 1 to 28 except that “Comparative polymers P′-1 to P′-14” were used instead of “Fluoropolymers P-1 to P-28 of the present invention”. The same operation was performed using a solvent, a basic compound, and a photoacid generator to prepare resists shown in Table 8.

Subsequently, in the same manner as in “Examples 1 to 28”, the prepared resist was spin-coated on a silicon wafer on which a silicon oxide film was formed to obtain a resist film, and then patterned in the same manner.
<Formation and evaluation of pattern>
When the obtained resist pattern was observed with an electron microscope, the rectangular pattern of the photomask was distorted and transferred as shown in Table 9.

<Dry etching>
As in Examples 1 to 28, when the silicon oxide film was dry-etched and the pattern of the silicon oxide film was observed with an electron microscope, the pattern was lost due to the resist being attacked by etching.

Claims (9)

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

(In the formula, A is an organic group having an alicyclic hydrocarbon group having 3 to 25 carbon atoms or an aromatic hydrocarbon group having 5 to 25 carbon atoms, and any number of hydrogen atoms in the organic group is a hydroxy group. May be substituted with an alkoxy group having 1 to 4 carbon atoms, an acetoxy group or an alkyl group having 1 to 4 carbon atoms, and each R ¹ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. And R ² each independently represents an acetal bond, a hemiacetal bond or a hemiacetal ester bond, and R ³ each independently represents an aliphatic hydrocarbon group having 1 to 15 carbon atoms or an aromatic hydrocarbon group having 5 to 15 carbon atoms. Or an organic group in which a plurality of these groups are linked, n is an integer of 1 to 3, and m is an integer of 1 to 3.) The fluorine-containing polymer according to claim 1, wherein A is an adamantylene group. The fluorine-containing polymer according to claim 1 or ^2, wherein R ² is an acetal bond represented by formula (4).

(R ⁵ and R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms, or a hydrocarbon group in which these groups are connected to each other to form a ring.) Further, olefins containing double bonds, fluorine-containing olefins, acrylic esters, methacrylic esters, fluorine-containing acrylic esters, fluorine-containing methacrylate esters, norbornene compounds, fluorine-containing norbornene compounds, styrene compounds, fluorine-containing styrene compounds The fluorine-containing polymer according to any one of claims 1 to 3, comprising a repeating unit obtained by cleaving a double bond of one or more monomers selected from vinyl ether and fluorine-containing vinyl ether. A resist comprising the fluoropolymer according to claim 1, a solvent, and a photoacid generator. Applying the resist according to claim 5 on a substrate (A);
A step (B) of exposing with a high energy beam which is an electromagnetic wave or an electron beam having a wavelength of 380 nm or less through a photomask after the heat treatment;
The pattern formation method including the process (C) which develops using a developing solution, without heat-processing or after heat-processing. The pattern formation method according to claim 6, wherein the step (B) is a step (B) by an immersion lithography method using a laser beam having a wavelength of 193 nm or a wavelength of 243 nm as a high energy ray. The pattern forming method according to claim 6, wherein the step (B) is a step (B) in which soft X-ray light having a wavelength of 10 nm or more and 14 nm or less is used for the high energy ray. A fluorine-containing monomer represented by the following formula (2).

(In the formula, A is an organic group having an alicyclic hydrocarbon group having 3 to 25 carbon atoms or an aromatic hydrocarbon group having 5 to 25 carbon atoms, and any number of hydrogen atoms in the organic group is a hydroxy group. May be substituted with an alkoxy group having 1 to 4 carbon atoms, an acetoxy group or an alkyl group having 1 to 4 carbon atoms, and each R ¹ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. And R ² each independently represents an acetal bond, a hemiacetal bond or a hemiacetal ester bond, and R ³ each independently represents an aliphatic hydrocarbon group having 1 to 15 carbon atoms or an aromatic hydrocarbon group having 5 to 15 carbon atoms. Or an organic group in which a plurality of these groups are linked, n is an integer of 1 to 3, and m is an integer of 1 to 3.)