JP2009300463A - Composition for forming resist protective film and method for formation of resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for the formation of a resist protective film and a method for forming a resist pattern. <P>SOLUTION: The composition for the formation of a resist protective film contains a fluoropolymer (F)-containing and alkali-soluble material for a resist protective film and a solvent containing at least one fluorine-based solvent (S) selected from hydrofluorocarbon solvents and hydrofluoro ether solvents; and the composition is to be applied to the surface of a photosensitive resist layer containing a resist polymer (R) that can be enhanced in the solubility in an alkali by an action of an acid and has a fluorine content lower than that of the fluoropolymer (F). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resist protective film forming composition and a method for forming a resist pattern.

In the manufacture of integrated circuits such as semiconductors, lithography is performed by projecting a mask pattern image obtained by irradiating light from an exposure light source onto a mask onto a photosensitive resist on a substrate and transferring the pattern image to the photosensitive resist. The method is used. Usually, the projection of the pattern image is performed by a scanning method. That is, the pattern image is projected by projecting the pattern image onto the photosensitive resist via a projection lens that moves relatively on the photosensitive resist.
The resolution of the pattern image transferred to the photosensitive resist increases as the light from the exposure light source becomes shorter wavelength light. For this reason, short wavelength light (ArF excimer laser, F ₂ excimer laser, etc.) of 220 nm or less has been studied as an exposure light source.

  Furthermore, an immersion lithography method using a phenomenon in which the wavelength of light in the liquid medium is a reciprocal of the refractive index of the liquid medium, that is, a liquid medium having a high refractive index between the lower portion of the projection lens and the upper portion of the photosensitive resist ( Hereinafter, a method of projecting a pattern image of a mask onto a photosensitive resist through a projection lens while being filled with an immersion liquid) has been studied in recent years.

  In the immersion lithography method, since the space between the projection lens and the photosensitive resist is filled with the immersion liquid, the components of the photosensitive resist (photo acid generator, etc.) are eluted into the immersion liquid. The photosensitive resist is absorbed by the immersion liquid. There are concerns such as swelling. Therefore, there is an attempt to suppress elution and swelling of the photosensitive resist by providing a resist protective film layer on the surface of the photosensitive resist in the immersion lithography method.

As a resist protective film material, an alkali-soluble fluorine-containing polymer having a specific contact angle with respect to water and containing a repeating unit formed by polymerization of an acyclic polyfluoroalkyl group-containing acrylate is known. . For example, for a resist protective film comprising a copolymer of the following compound (f ^p 1) and the following compound (b ^p 1) or a copolymer of the following compound (f ^p 1) and the following compound (b ^p 2) Polymers (see Patent Documents 1 to 3) are known.
_{CH 2 = CH-C (O} ) O- (CH 2) 2 - (CF 2) 7 CF 3 (f p 1),
_{CH 2 = C (CH 3)} -C (O) OH (b p 1),
_{CH 2 = C (CH 3)} -CH (CH 3) CH 2 -C (CF 3) 2 (OH) (b p 2).

Also known is a resist protective film composition comprising an alkali-soluble polymer obtained by polymerizing a monomer having a —C (CF ₃ ) ₂ (OH) group, such as the following compound, and a fluorosurfactant. (See Patent Document 4).

  The resist protective film materials disclosed in Patent Documents 1 to 4 are usually prepared by being dissolved in an organic solvent (alcohol, ester, ketone, etc.) that does not contain fluorine atoms to prepare a liquid resist protective film forming composition. The resist protective film layer made of the resist protective film material is formed by applying the resist protective film-forming composition onto the surface of the photosensitive resist layer, and further removing the organic solvent by heat treatment to form the surface of the photosensitive resist layer. This is because it is formed. Patent Document 2 describes a perfluoroether solvent such as perfluoro-2-butyltetrahydrofuran as the organic solvent.

JP 2006-193687 A International Publication No. 2006/070695 Pamphlet JP 2006-243308 A JP 2005-352384 A

  However, the influence of the organic solvent on the photosensitive resist layer has not been sufficiently studied in any document. Patent Document 1 only describes a mixed solvent composed of an alcohol and another organic solvent not containing fluorine atoms as the organic solvent. According to the study by the present inventors, when a resist protective film layer formed from the resist protective film forming composition is provided, the shape accuracy of the resist pattern may be lowered. Further, according to the study by the present inventors, an alkali-soluble resist protective film material containing a fluoropolymer has low compatibility with a perfluoroether solvent and does not form a stable resist protective film forming composition. There was a case.

  Furthermore, when a resist protective film layer is provided on the surface of the photosensitive resist in the immersion lithography method, the immersion liquid follows the projection lens that moves at high speed on the surface of the resist protective film layer. From the viewpoint of. However, a resist protective film material having such characteristics and excellent in dynamic liquid repellency is not known.

  The present inventors have provided an immersion in which a resist protective film layer formed from a resist protective film-forming composition containing a specific resist protective film material and a specific fluorine-based solvent is provided on the surface of a specific photosensitive resist layer. We have obtained the knowledge that a resist pattern with high shape accuracy can be formed by lithography. Furthermore, the present inventors have found a stable resist protective film forming composition capable of forming a resist protective film layer having excellent dynamic liquid repellency.

That is, the present invention provides the following inventions.
<1> A resist protective film-forming composition that is used by being applied to the surface of the following photosensitive resist layer, comprising the following resist protective film material and the following solvent.
Photosensitive resist layer: A layer containing a resist polymer (R) which is a polymer whose alkali solubility is increased by the action of an acid and has a lower fluorine content than the fluoropolymer (F).
Resist protective film material: An alkali-soluble material containing a fluoropolymer (F).
Solvent: A solvent containing at least one fluorine-based solvent (S) selected from hydrofluorocarbon solvents and hydrofluoroether solvents.

  <2> The resist protective film forming composition according to <1>, wherein the resist polymer (R) is a resist polymer containing no fluorine atom.

<3> Polymerization of a monomer (b ^M ) in which the resist protective film material has at least one functional group selected from a hydroxy group, a carboxy group, a sulfonic acid group, a sulfonylamide group, an amino group, and a phosphoric acid group The composition for forming a resist protective film according to <1> or <2>, comprising an alkali-soluble fluoropolymer (F ^P ) containing the repeating unit (B ^U ) formed by the above step.

<4> The resist protective film forming composition according to any one of <1> to <3>, wherein the solvent is a mixed solvent containing a fluorine-based solvent (S) and an organic solvent not containing a fluorine atom.
<5> The resist protective film forming composition according to any one of <1> to <4>, wherein the fluorine-based solvent (S) is 1,3-bis (trifluoromethyl) benzene.

<6> A resist pattern forming method by immersion lithography, which is a polymer whose alkali solubility is increased by the action of an acid on the surface of a substrate and has a lower fluorine content than the fluoropolymer (F) A step of forming a photosensitive resist layer containing the polymer (R), a resist protective film forming composition containing the following resist protective film material and the following solvent is applied to the surface of the photosensitive resist layer, and a solvent is further added. The substrate on which the resist pattern is formed is obtained by performing the steps of removing and forming a resist protective film layer on the surface of the photosensitive resist layer, an immersion lithography step, and a step of developing the photosensitive resist layer in this order. A resist pattern forming method to be obtained.
Resist protective film material: a material containing an alkali-soluble fluoropolymer (F).
Solvent: A solvent containing at least one fluorine-based solvent (S) selected from hydrofluorocarbon solvents and hydrofluoroether solvents.

  According to the present invention, a stable resist protective film-forming composition that has excellent resist protective film characteristics (characteristics that suppress swelling and elution of the photosensitive resist, etc.) and that is difficult to denature the photosensitive resist layer, and further, dynamic repellency A resist protective film-forming composition having excellent properties is provided. According to the present invention, it is possible to perform an immersion lithography method capable of forming a highly accurate resist pattern at high speed.

In this specification, the compound represented by the formula (a) is referred to as the compound (a), and the group represented by the formula —CF ₂ C (CF ₃ ) (OH) (CH ₂ ) _mr — is represented as —CF ₂ C ( CF ₃ ) (OH) (CH ₂ ) _mr − is also described. Other compounds and other groups are also described in the same manner. Further, symbols in the group are as defined above unless otherwise specified.

The present invention provides a resist protective film-forming composition that is applied to the surface of the following photosensitive resist layer and used, and includes the following resist protective film material and the following solvent.
Photosensitive resist layer: A layer containing a resist polymer (R) which is a polymer whose alkali solubility is increased by the action of an acid and has a lower fluorine content than the fluoropolymer (F).
Resist protective film material: An alkali-soluble material containing a fluoropolymer (F).
Solvent: A solvent containing at least one fluorine-based solvent (S) selected from hydrofluorocarbon solvents and hydrofluoroether solvents.

  The resist protective film forming composition of the present invention makes it possible to form a resist pattern with high shape accuracy. The reason is not necessarily clear, but it is considered that the fluorinated solvent (S) is hardly compatible with the resist polymer (R). Therefore, when the resist protective film forming composition of this invention is apply | coated to the surface of the photosensitive resist layer, it is thought that modification | denaturation (swelling, melt | dissolution, etc.) of the photosensitive resist layer by a solvent does not occur easily. Further, the fluorine-based solvent (S) is a fluorine-based solvent partially having a hydrogen atom, and is considered highly compatible with the fluorine-containing polymer (F). Therefore, the resist protective film forming composition of the present invention is considered to easily form a stable liquid composition suitable for forming a uniform coating film.

  The photosensitive resist layer in the present invention is preferably a photosensitive resist layer containing a resist polymer (R).

  The resist polymer (R) in the present invention is not particularly limited as long as it is a polymer whose alkali solubility is increased by the action of an acid and has a lower fluorine content than the fluoropolymer (F). The resist polymer (R) may be a polymer containing a fluorine atom or a polymer not containing a fluorine atom. In the former case, the fluorine content of the resist polymer (R) is preferably 60% by mass or less, and particularly preferably less than 30% by mass. Further, the lower limit of the fluorine content is preferably more than 0% by mass.

The resist polymer (R) includes the following group (r-1), the following group (r-2), —C (CF ₃ ) ₂ (OZ ^R ) (hereinafter also referred to as group (r-3)), and A polymer having at least one group (r) selected from —C (CF ₃ ) (OZ ^R ) — (hereinafter also referred to as group (r-4)) is preferable.

The symbols in the formula have the following meanings (the same applies hereinafter).
X ^R1 : an alkyl group having 1 to 6 carbon atoms.
Y ^R1 : a divalent group having 4 to 20 carbon atoms which forms a ring hydrocarbon group in cooperation with the carbon atom in the formula.
X ^{R2 is} an alkyl group having 1 to 20 carbon atoms, and three X ^R2s may be the same or different.
Z ^R : an alkyl group, an alkoxyalkyl group, an alkoxycarbonyl group or an alkylcarbonyl group having 1 to 20 carbon atoms.
^{However, X R1, Y R1, X} R2 or carbon atoms in ^{Z R} - is between the carbon atoms -O -, - C (O) O- or -C (O) - is may be inserted, also , X ^R1 , Y ^R1 , X ^R2 or Z ^R may be bonded to a fluorine atom, a hydroxy group or a carboxy group.

The polymer is a polymer whose alkali solubility is increased by the action of an acid. The polymer having the group (r-1) or the group (r-2) is considered to increase alkali solubility because the carboxylate moiety is cleaved by the action of an acid to form a carboxy group. In addition, in the polymer having the group (r-3) or the group (r-4), the ether moiety is cleaved by the action of an acid, and —C (CF ₃ ) ₂ (OH) or —C (CF ₃ ) (OH )-Is formed, and the alkali solubility is considered to increase.

X ^R1 in the present specification is preferably a C 1-6 alkyl group or a C 1-6 alkyl group containing an etheric oxygen atom, and particularly preferably a methyl group or an ethyl group.
In the present specification, the divalent group formed by Y ^R1 and the carbon atom in the formula is preferably an aliphatic group, particularly preferably a saturated aliphatic group. The divalent group may be a monocyclic hydrocarbon group or a polycyclic hydrocarbon group. The divalent group is preferably a polycyclic hydrocarbon group, particularly preferably a bridged ring hydrocarbon group.
In the present specification, X ^R2 is an alkyl group having 1 to 3 carbon atoms, or two are alkyl groups having 1 to 3 carbon atoms and one is a cyclic hydrocarbon group having 4 to 20 carbon atoms. Preferably there is.

  The group (r-1) is preferably any group represented by the following formula.

  The group (r-2) is preferably any group represented by the following formula.

The group (r-3) is preferably —C (CF ₃ ) ₂ (OCH ₂ OZ ^R1 ) (where Z ^R1 represents a hydrocarbon group having 1 to 12 carbon atoms, the same shall apply hereinafter), and —C (CF ₃ ) ₂ (OCH ₂ OCH ₃ ), —C (CF ₃ ) ₂ (OCH ₂ OCH ₂ CH ₃ ), —C (CF ₃ ) ₂ (OCH ₂ OC (CH ₃ ) ₃ ) or one of the following groups Is particularly preferred.

Group (r-4) _{is, -C (CF 3) (OCH} 2 OZ R1) - are _{preferred, -C (CF 3) (OCH} 2 OCH 3) -, - C (CF 3) (OCH 2 OCH 2 CH _{3) -, - C (CF} 3) (OCH 2 OC (CH 3) 3) - or any of the groups below are particularly preferred.

The resist polymer (R) is a repeating unit (R ^U ) formed by polymerization of at least one monomer (r ^M ) selected from the following compound (r1), the following compound (r2) and the following compound (r3). ) Is preferred.

The symbols in the formula have the following meanings (the same applies hereinafter).
T ^R : a hydrogen atom, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or a fluoroalkyl group having 1 to 3 carbon atoms.
Q ^R1 : a group represented by the formula —CF ₂ C (CF ₃ ) (OZ ^R ) (CH ₂ ) _mr —, or a formula —CH ₂ CH ((CH ₂ ) _nr C (CF ₃ ) ₂ (OZ ^R ) _{) (CH 2) mr} - group represented by the.
mr and nr: each independently 0, 1 or 2.

T ^R is a hydrogen atom, a fluorine atom, preferably a methyl group or a trifluoromethyl group, a hydrogen atom or a methyl group is particularly preferred.
Mr in Q ^R1 is, 1 is preferred. Nr in Q ^R1, 0 is preferable. Q ^R1 _{is, -CF 2 C (CF 3)} (OCH 2 OZ R1) CH 2 - or _{-CH 2 CH (C (CF 3} ) 2 (OCH 2 OZ R1)) CH 2 - is preferred.

  The compound (r1) is preferably the following compound (r11), the following compound (r12), the following compound (r13), the following compound (r14) or the following compound (r15).

  The compound (r2) is preferably the following compound (r21) or the following compound (r22).

Compound (r3) is CF ₂ ═CFCF ₂ C (CF ₃ ) (OCH ₂ OZ ^{R 1} ) CH ₂ CH═CH ₂ or CF ₂ ═CFCH ₂ CH (C (CF ₃ ) ₂ (OCH ₂ OZ ^{R 1} )) CH ₂ CH═CH ₂ is preferred.

  Specific examples of the compound (r1) include the following compounds.

  Specific examples of the compound (r2) include the following compounds.

  Specific examples of the compound (r3) include the following compounds.

The resist polymer (R) preferably contains 10 to 90 mol%, particularly preferably 30 to 60 mol% of the repeating unit (R ^U ) with respect to all repeating units. In the immersion lithography method in this case, the exposed portion of the resist polymer (R) can be easily removed with an alkaline solution.

The resist polymer (R) may contain a repeating unit other than the repeating unit (R ^U ) (hereinafter also referred to as other unit (R ^U )). In this case, the resist polymer (R) preferably contains 20 to 60 mol% of other units (R ^U ) with respect to all repeating units.
The other unit (R ^U ) is not particularly limited, and at least one compound (q) selected from the following compound (q1) and the following compound (q2) and / or the following compound (p1) and the following compound ( A repeating unit formed by polymerization of at least one compound (p) selected from p2) is preferred.

The symbols in the formula have the following meanings (the same applies hereinafter).
T ^Q and T ^P : each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or a fluoroalkyl group having 1 to 3 carbon atoms.
Y ^Q1 : a trivalent group having 4 to 20 carbon atoms which forms a bridged ring hydrocarbon group in cooperation with the carbon atom in the formula.
Y ^Q2 : a divalent group having 4 to 20 carbon atoms that forms a cyclic hydrocarbon group in cooperation with the carbon atom in the formula.
Y ^P1 : a trivalent group having 5 to 20 carbon atoms that forms a bridged ring hydrocarbon group in cooperation with a carbon atom in the formula, and a hydroxy group or a carboxy group is bonded to the carbon atom in the group Group.
Y ^P2 : a divalent group having 4 to 20 carbon atoms that forms a cyclic hydrocarbon group together with the carbon atom in the formula, and a hydroxy group or a carboxy group is bonded to the carbon atom in the group Group.
However, —O—, —C (O) O—, or —C (O) — may be inserted between carbon atoms in Y ^Q1 , Y ^Q2 , Y ^P1 or Y ^P2 .

T ^Q and ^TP are each independently preferably a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, particularly preferably a hydrogen atom or a methyl group.

The trivalent group formed by ^YQ1 and the carbon atom in the formula is preferably an aliphatic group, particularly preferably a saturated aliphatic group.
The divalent group formed by ^YQ2 and the carbon atom in the formula is preferably an aliphatic group, particularly preferably a saturated aliphatic group. The divalent group may be a monocyclic hydrocarbon group or a polycyclic hydrocarbon group.
The trivalent group formed by ^YP1 and the carbon atom in the formula is preferably an aliphatic group, particularly preferably a saturated aliphatic group.
The divalent group formed by ^YP2 and the carbon atom in the formula is preferably an aliphatic group, particularly preferably a saturated aliphatic group. The divalent group may be a monocyclic hydrocarbon group or a polycyclic hydrocarbon group.
Between carbon atoms, -C (O) O- or ^{-C (O) - - Y Q1} , Y Q2, the carbon atom in ^{Y P1} or ^{Y P2} if is inserted, -C (O) O- Is preferably inserted.

  The compound (q1) is preferably the following compound (q11), the following compound (q12) or the following compound (q13).

  The compound (q2) includes the following compound (q21), the following compound (q22), the following compound (q23), the following compound (q24), the following compound (q25), the following compound (q27), the following compound (q28), or the following compound. (29) is preferred.

  The compound (p1) is preferably the following compound (p11), the following compound (p12) or the following compound (p13), and particularly preferably the following compound (p12).

  Specific examples of the compound (q1) include the following compounds.

  Specific examples of the compound (q2) include the following compounds.

  Specific examples of the compound (p1) include the following compounds.

  The weight average molecular weight of the resist polymer (R) is preferably from 1,000 to 100,000, particularly preferably from 1,000 to 50,000.

A preferred embodiment of the resist polymer (R), based on all repeating units comprise 10 to 60 mole% of recurring units ^{(R U),} a polymer containing other units ^{(R U)} 40 to 90 mole% Can be mentioned.

The repeating unit (R ^U ) in the above embodiment is particularly preferably a repeating unit formed by polymerization of the compound (r1). The other unit (R ^U ) in the above embodiment is preferably a repeating unit formed by polymerization of the compound (q) and the compound (p), and a repeating unit formed by polymerization of the compound (q2) and the compound (p1) is Particularly preferred.
As for the weight average molecular weight of the polymer in the said aspect, 1000-30000 are preferable.

The photosensitive resist layer in the present invention preferably contains a photoacid generator, and particularly preferably contains 0.1 to 10% by mass of the photoacid generator with respect to the resist polymer (R).
A photo-acid generator will not be specifically limited if it is a compound which has the group which generate | occur | produces an acid by irradiation of actinic light (Actinic light means the wide concept including radiation). The compound may be a non-polymer compound or a polymer compound. Moreover, 1 type may be used for a photo-acid generator, and 2 or more types may be used for it.

  The photoacid generator is a photoacid generator selected from the group consisting of onium salts, halogen-containing compounds, diazoketones, sulfone compounds, sulfonic acid compounds, diazodisulfones, diazoketosulfones, iminosulfonates, and disulfones. Agents are preferred.

  Specific examples of the photoacid generator include diphenyliodonium triflate, diphenyliodonium pyrenesulfonate, diphenyliodonium hexafluoroantimonate, diphenyliodonium dodecylbenzenesulfonate, bis (4-tert-butylphenyl) iodonium triflate, bis (4- tert-butylphenyl) iodonium dodecylbenzenesulfonate, triphenylsulfonium triflate, triphenylsulfonium nonanate, triphenylsulfonium perfluorooctanesulfonate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, triphenylsulfonium trifluoromethanesulfone Nato, triphenylsulfonium carbonate Fursulfonium, 1- (naphthylacetomethyl) thiolanium triflate, cyclohexylmethyl (2-oxocyclohexyl) sulfonium triflate, dicyclohexyl (2-oxocyclohexyl) sulfonium triflate, dimethyl (4-hydroxynaphthyl) sulfonium tosylate, dimethyl (4-hydroxynaphthyl) sulfonium dodecylbenzenesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium naphthalenesulfonate, triphenylsulfonium camphorsulfonate, (4-hydroxyphenyl) benzylmethylsulfonium toluenesulfonate, (4-methoxyphenyl) phenyliodonium trifluoromethane Sulfonate, bis (t-butylphenyl) iodonium trif Oromethanesulfonate, phenyl-bis (trichloromethyl) -s-triazine, methoxyphenyl-bis (trichloromethyl) -s-triazine, naphthyl-bis (trichloromethyl) -s-triazine, 1,1-bis (4-chlorophenyl) ) -2,2,2-trichloroethane, 4-trisphenacylsulfone, mesitylphenacylsulfone, bis (phenylsulfonyl) methane, benzoin tosylate, 1,8-naphthalenedicarboxylic acid imide triflate.

  The resist protective film material in the present invention is an alkali-soluble material that includes the fluoropolymer (F) and has the required optical characteristics and can suppress swelling and elution of the photosensitive resist layer. There is no particular limitation.

The fluoropolymer (F) in the present invention is not particularly limited as long as it is a fluoropolymer having a higher fluorine content than the fluoropolymer (F). The fluorine content of the fluoropolymer (F) is preferably 5% by mass or more, particularly preferably 30% by mass or more. The upper limit of the fluorine content is preferably 76% by mass or less.
The weight average molecular weight of the fluoropolymer (F) is preferably from 1,000 to 100,000, particularly preferably from 1,000 to 50,000.

The fluoropolymer (F) is obtained by polymerizing a monomer (b ^M ) having at least one functional group selected from a hydroxy group, a carboxy group, a sulfonic acid group, a sulfonylamide group, an amino group, and a phosphoric acid group. formed repeat units fluorinated polymer comprising ^{(B U) (F P)} is preferable. The fluorine-containing polymer ( ^FP ) is an alkali-soluble fluorine-containing polymer because it contains a repeating unit (B ^U ), and the resist protective film material containing the fluorine-containing polymer ( ^FP ) is an alkali-soluble material. It is. The hydroxy group may be an alcoholic hydroxy group or a phenolic hydroxy group.

The monomer (b ^M ) in the present specification is preferably a monomer having a hydroxy group or a carboxy group, and —C (CF ₃ ) ₂ (OH), —C (CF ₃ ) (OH) — or —COOH. The following compound (b1), the following compound (b2), the following compound (b3) or the following compound (b4) is particularly preferable.

The symbols in the formula have the following meanings (the same applies hereinafter).
Q ^BM1: Formula _{-CF 2 C (CF 3) (} OH) (CH 2) mb - , a group represented by formula _{-CH 2 CH ((CH 2)} nb C (CF 3) 2 (OH)) (CH ₂ ) A group represented by _mb- or a group represented by the formula -CH ₂ CH (COOH) (CH ₂ ) _mb- .
mb and nb: each independently 0, 1 or 2.
R ^BM2 : a hydrogen atom, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or a fluoroalkyl group having 1 to 3 carbon atoms.
Q ^BM2 and Q ^BM3 : each independently an (rb + 1) -valent hydrocarbon group having 1 to 20 carbon atoms.
rb: 1 or 2.
^QBM4 : A single bond or a C1-C10 divalent hydrocarbon group.
^However, Q ^BM2, hydrogen atoms in ^{Q BM3} or ^{Q BM4} may be substituted with a fluorine atom.

As for mb in ^QBM1 of a compound (b1), 1 is preferable. ^Nb in QBM1 is preferably 0. ^QBM1 is preferably —CF ₂ C (CF ₃ ) (OH) CH ₂ —, —CH ₂ CH (C (CF ₃ ) ₂ (OH)) CH ₂ — or —CH ₂ CH (COOH) CH ₂ —. .

  Specific examples of the compound (b1) include the following compounds.

R ^BM2 of the compound (b2) is preferably a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, particularly preferably a hydrogen atom or a methyl group.

(Rb + 1) valent hydrocarbon group in ^{Q BM3} of ^{Q BM2} and compound (b3) compound (b2) are each independently preferably (rb + 1) valent ring system hydrocarbon group having 1 to 20 carbon atoms. The ring-type hydrocarbon group may be a group consisting only of a ring-type hydrocarbon group or a group containing a ring-type hydrocarbon group in the group. The cyclic hydrocarbon group may be an aliphatic group or an aromatic group. The ring hydrocarbon group may be a monocyclic hydrocarbon group or a polycyclic hydrocarbon group. The polycyclic hydrocarbon group may be a bridged ring hydrocarbon group.

Q ^BM2 and Q ^BM3 are particularly preferably any of the following groups.

  Specific examples of the compound (b2) include the following compounds.

  Specific examples of the compound (b3) include the following compounds.

Q ^BM4 of the compound (b4) is preferably a single bond or a methylene group.
Specific examples of the compound (b4) include the following compounds.

The weight average molecular weight of the fluorine-containing polymer ^{(F P)} is preferably from 1,000 to 100,000, particularly preferably 1,000 to 50,000.

The fluoropolymer (F ^P) may be a fluorine-containing polymer consisting of a repeating unit (B ^M), and the repeating unit (B ^M), and other recurring units other than the repeating unit (B ^M) The fluorine-containing polymer containing may be sufficient.

The first preferred embodiment of the resist protective film material in the present invention includes a repeating unit (B ^U ) and a repeating unit (F ^U ) formed by polymerization of a fluorine-containing monomer (f ^M ), A resist protective film material comprising a fluoropolymer (F ^PC ) containing 10 mol% or more of repeating units (B ^U ) and 1 mol% or more of repeating units (F ^U ) with respect to all repeating units. .
The fluorine-containing polymer (F ^PC ) may be a polymer composed only of repeating units (F ^U ) and repeating units (B ^U ), or may be a polymer containing other units. The repeating unit (F ^U ) in the fluoropolymer (F ^PC ) is usually one type, and the repeating unit (B ^U ) is also usually one type.
The fluoropolymer (F ^PC ) preferably contains 1 to 70 mol% or more of repeating units (F ^U ) with respect to all repeating units. The fluoropolymer ^{(F P),} based on all repeating units, the repeating units ^{(B U),} preferably contains 30 to 99 mol%.
The fluorine content of the fluoropolymer (F ^PC ) is preferably 20% by mass or more.
The weight average molecular weight of the fluoropolymer (F ^PC ) is preferably from 1,000 to 100,000, particularly preferably from 1,000 to 50,000.

The fluorine-containing monomer (f ^M ) in the present specification is not particularly limited as long as it is a fluorine-containing monomer other than the monomer (b ^M ) having a fluorine atom, and the fluorine content is 30 to 76% by mass. A monomer is preferred.

The fluorine-containing monomer (f ^M ) is preferably a monomer having a fluorine-containing ring structure or a monomer forming a repeating unit having a fluorine-containing ring structure by cyclopolymerization.
The fluorinated polymer (F ^PC ) in this case is a fluorinated polymer having a fluorinated ring structure derived from the fluorinated monomer (f ^M ) and excellent in dynamic water and oil repellency, and having repeating units ( Since B ^U ) is contained, it is an alkali-soluble fluoropolymer.
Therefore, in the immersion lithography method provided with the resist protective film layer formed from the resist protective film forming composition in this case, not only the swelling and elution of the photosensitive resist layer is suppressed, but also the immersion liquid is used. It follows the projection lens that moves at high speed on the resist protective film layer. Therefore, it is possible to perform the immersion lithography method capable of transferring a mask pattern image with high accuracy.

The fluorine-containing monomer (f ^M ) is preferably the following compound (f1), the following compound (f2), the following compound (f3) or the following compound (f4).

The symbols in the formula have the following meanings (the same applies hereinafter).
R ^FM : a hydrogen atom, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or a fluoroalkyl group having 1 to 3 carbon atoms.
W ^FM : a fluorine-containing saturated hydrocarbon group having a fluorine-containing ring structure having 4 to 20 carbon atoms. ^However, carbon atoms in ^{W FM} - is between the carbon atoms -O -, - C (O) - or -C (O) O-may be inserted.
Q ^FM : a group selected from the group consisting of a methylene group, a dimethylene group, a trimethylene group, a tetramethylene group, an oxymethylene group, an oxydimethylene group, and an oxytrimethylene group. However, the hydrogen atom in the group may be substituted with a group having 1 to 12 carbon atoms selected from the group consisting of an alkyl group, a fluoroalkyl group, an alkoxy group and a fluoroalkoxy group, or a fluorine atom.
X ^FM : A hydrogen atom or a fluorine atom, and the three X ^FMs may be the same or different.
Y ^FM : a fluorine atom or a C 1-3 perfluoroalkoxy group.
^ZFM1 , ^ZFM2 , ^ZFM3 and ^ZFM4 : each independently a fluorine atom or a C1-C6 perfluoroalkyl group.
R ^FM of the compound (f1) is preferably a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, particularly preferably a hydrogen atom or a methyl group.

  The compound (f1) is preferably the following compound (f11), the following compound (f12a), the following compound (f12b) or the following compound (f13).

The symbols in the formula have the following meanings (the same applies hereinafter).
Q ^FM1 : A single bond or a methylene group.
W ^FM2 : A fluorine atom or a trifluoromethyl group.
Q ^FM2 : —CF ₂ — or —C (CF ₃ ) ₂ —, and two Q ^{FM2 s} may be the same or different.
W ^FM3 : a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms.
Q ^FM3 : a C 3-11 perfluoroalkylene group that forms a fluorine-containing monocyclic hydrocarbon group in cooperation with a carbon atom in the formula.

Among the compounds (f11), a compound in which ^QFM1 is a methylene group is a novel compound. The compound (f11) is obtained by reacting the following compound (pf11) with water to obtain the following compound (qf11), and then reacting the compound (qf11) with H—CHO to obtain the following compound (rf11). then compound (RF11) can be produced by reacting the _CH 2 ⁼ CR FM COCl.

  Specific examples of the compound (f11) include the following compounds.

Compound (f12a) is a novel compound. The compound (f12a) is obtained by esterifying the following compound (of12a) and R ^f -COF to obtain the following compound (pf12a), and the following compound (qf12a) is obtained by liquid phase fluorination reaction of the compound (pf12a). The compound (qf12a) is thermally decomposed in the presence of KF to obtain the following compound (rf12a), the compound (rf12a) is reduced to obtain the following compound (sf12a), and the compound (sf12a) and CH ₂ = It can be produced by reacting CR ^F COCl.

The symbols in the formula have the following meanings (the same applies hereinafter).
R ^f : a perfluoroalkyl group which may contain an etheric oxygen atom having 1 to 20 carbon atoms.
W ^HM2 : A group corresponding to W ^FM2 , which is a hydrogen atom or a methyl group.
Q ^HM2 : A group corresponding to Q ^FM2 , and —CH ₂ — or —C (CH ₃ ) ₂ —.

  Compound (f12b) is a novel compound. Compound (f12b) can be produced in the same manner except that the following compound (of12b) is used in place of compound (of12a).

  Specific examples of the compound (f12a) and the compound (f12b) include the following compounds.

Q ^FM3 may be a linear perfluoroalkylene group or a branched perfluoroalkylene group. Q ^FM3 is preferably-(CF ₂ ) _wm- . However, wm shows the integer of 3-9, and 3-6 are preferable.

  Specific examples of the compound (f13) include the following compounds.

^{Q F} of the compound (f2) _{^{is, -CH 2 CH (T FM1)}} CH 2 -, - OCF 2 CF 2 -, - OCF (T FM2) CF 2 - or -OCF ₂ CF ^{(T FM2)} - are preferred. However, ^TFM1 shows a C1-C6 alkyl group or a C1-C6 fluoroalkyl group, and ^TFM2 shows a C1-C6 perfluoroalkyl group (the same applies hereafter).

The compound (f2) is preferably the following compound (f21), the following compound (f22), the following compound (f23) or the following compound (f24).
^{_{CF 2 = CFCH 2 CH (T}} FM1) CH 2 CH = CH 2 (f21),
CF ₂ = CFOCF ₂ CF ₂ C (X ^FM ) = C (X ^FM ) ₂ (f22),
^{_{CF 2 = CFOCF 2 CF (T}} FM2) C (X FM) = C (X FM) 2 (f23),
_{^{CF 2 = CFOCF (T FM2)}} 2 CF 2 C (X FM) = C (X FM) 2 (f24).

  Specific examples of the compound (f2) (excluding the compound (f21) described later) include the following compounds.

Compound (f21) is a novel compound. Compound (f21) is obtained by reacting the following compound (pf21) with CF ₂ ClCFClI to obtain the following compound (qf21), and then reacting the following compound (qf21) with CH ₂ = CHCH ₂ MgCl to produce the following compound (rf21). Then, the compound (rf21) can be produced by dechlorination reaction in the presence of Zn.
CH ₂ = CHT ^FM1 (pf21),
CF ₂ ClCFClCH ₂ CHIT ^FM1 (qf21),
^{_{CF 2 ClCFClCH 2 CH (T FM1}} ) CH 2 CH = CH 2 (rf21).

  Specific examples of the compound (f21) include the following compounds.

  Specific examples of the compound (f3) include the following compounds.

  Specific examples of the compound (f4) include the following compounds.

Fluoropolymer as a preferred embodiment of ^{(F PC),} consisting only of the repeating units ^{(F U)} and repeating units ^{(B U),} based on all repeating units, the repeating units ^{(F U)} 1 to 30 mol% And a polymer containing 70 to 99 mol% of the repeating unit (B ^U ).
The repeating unit (F ^U ) in the above embodiment is preferably a repeating unit formed by polymerization of the compound (f1) or the compound (f2).
The repeating unit (B ^U ) in the above embodiment is preferably a repeating unit formed by polymerization of the compound (b1), the compound (b2), the compound (b3) or the compound (b4).
As for the weight average molecular weight of the polymer of the said aspect, 1000-30000 are preferable.

As a second preferred embodiment of the resist protective film material in the present invention, a resist containing an alkali-soluble fluoropolymer (F ^Q ) and a fluoropolymer (Z) containing a repeating unit (F ^U ). A protective film composition may be mentioned. The resist protective film composition preferably contains 1 to 10% by mass of the fluoropolymer (Z) with respect to the fluoropolymer (F ^Q ). In this case, the fluoropolymer (F ^Q ) and the fluoropolymer (Z) are easily compatible with each other, and the film forming property of the resist protective film composition is excellent.

As a preferable aspect of a fluoropolymer ( ^FQ ), the fluoropolymer containing a repeating unit ( ^BU ) is mentioned.
From the viewpoint of alkali solubility, the fluoropolymer in the above embodiment preferably contains 5 mol% or more of repeating units (B ^U ), and particularly preferably contains 25 mol% or more.
The repeating unit (B ^U ) in the above embodiment is particularly preferably a fluorine-containing polymer consisting only of repeating units formed by polymerization of the compound (b1), the compound (b2), the compound (b3) or the compound (b4).
As for the weight average molecular weight of the fluoropolymer in the said aspect, 1000-50000 are preferable.

Preferable embodiments of the fluoropolymer (Z) include the following fluoropolymer (ZH) and the following fluoropolymer (ZC).
Fluoropolymer (ZH): A fluoropolymer composed of only repeating units (F ^U ).
Fluoropolymer (ZC): containing repeating units (F ^U ) and other units (F ^U ), and containing 1 to 70 mol% of repeating units (F ^U ) with respect to all repeating units A fluorine-containing polymer containing 30 to 99 mol% of F ^U ).

The repeating unit (F ^U ) in the above embodiment is preferably the compound (f1) or the compound (f2).
The other unit (F ^U ) in the above embodiment is preferably a repeating unit (B ^U ), particularly a repeating unit formed by polymerization of the compound (b1), the compound (b2), the compound (b3) or the compound (b4). preferable.
As for the weight average molecular weight of the fluoropolymer in the said aspect, 1000-50000 are preferable.

  The solvent in the present invention is not particularly limited as long as it is a solvent containing at least one fluorine-based solvent (S) selected from a hydrofluorocarbon-based solvent and a hydrofluoroether-based solvent.

  The hydrofluorocarbon-based solvent means a compound that is composed of only hydrogen atoms, fluorine atoms, and carbon atoms and is liquid at 25 ° C. The boiling point of the compound is preferably 60 to 160 ° C. Moreover, the carbon atom in the compound may form an alicyclic ring or an aromatic ring.

  The hydrofluoroether solvent means a compound which is composed of only etheric oxygen atoms, hydrogen atoms, fluorine atoms and carbon atoms and is liquid at 25 ° C. The boiling point of the compound is preferably 60 to 160 ° C. Moreover, the carbon atom in the compound may form an alicyclic ring or an aromatic ring. In the compound, two or more etheric oxygen atoms may be present.

The hydrofluoroether solvent is preferably R ^EF —O—R ^EH (where R ^EF represents a polyfluoroalkyl group which may contain an etheric oxygen atom having 4 to 12 carbon atoms, and R ^EH represents the number of carbon atoms). 1 to 8 alkyl groups are indicated.) Each of R ^EF and R ^EH may be a linear group or a branched group.
R ^EF is preferably a perfluoroalkyl group having 4 to 8 carbon atoms or a perfluoro (alkoxyalkyl) group having 4 to 8 carbon atoms.
R ^EH is preferably a methyl group or an ethyl group.

Specific examples of the hydrofluorocarbon-based solvent include CF ₃ CHFCHFCF ₂ CF ₃ , CF ₃ (CF ₂ ) ₅ H, CF ₃ (CF ₂ ) ₃ CH ₂ CH ₃ , CF ₃ (CF ₂ ) ₅ CH ₂ CH ₃ , Examples include CF ₃ (CF ₂ ) ₇ CH ₂ CH ₃ , 1,3-bis (trifluoromethyl) benzene, and the following compounds.

Specific examples of the hydrofluoroether solvent include CF ₃ (CF ₂ ) ₃ OCH ₃ , CF ₃ (CF ₂ ) ₅ OCH ₃ , F (CF ₂ ) ₆ OCH ₃ , F (CF ₂ ) ₇ OCH ₃ , F (CF ₂ ) ₈ OCH ₃ , F (CF ₂ ) ₉ OCH ₃ , F (CF ₂ ) ₁₀ OCH ₃ , H (CF ₂ ) ₆ OCH ₃ , F (CF ₂ ) ₃ OCF (CF ₃ ) CF ₂ OCH ₃ F (CF ₂ ) ₃ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) CF ₂ OCH ₃ , F (CF ₂ ) ₈ OCH ₂ CH ₂ CH ₃ , (CF ₃ ) ₂ CFCF ₂ CF ₂ OCH ₃ , F _{(CF 2) 2 O (CF} 2) 4 OCH 2 CH 3, (CF 3) 2 CFCF (CF 3) CF 2 OCH 3, (CF 3) 2 CFCF (CF 2 CF 3) OCH 3, CF 3 H ₂ OCF ₂ CHF ₂ and the like.

  The fluorinated solvent (S) is preferably 1,3-bis (trifluoromethyl) benzene.

The solvent in the present invention may be a solvent composed only of the fluorinated solvent (S), or an organic solvent other than the fluorinated solvent (S) and the fluorinated solvent (S) (hereinafter also referred to as other organic solvent). The mixed solvent containing these may be sufficient. In addition, the fluorine-type solvent (S) in this invention is 1 type normally.
From the viewpoint of compatibility with the resist protective film material, the solvent in the present invention includes a fluorine-based solvent (S) and an organic solvent other than the fluorine-based solvent (S) (hereinafter also referred to as other organic solvents). Mixed solvents are preferred.
The mixed solvent contains 90% by mass or more and less than 100% by mass of the fluorine-based solvent (S) with respect to the total mass of the fluorine-based solvent (S) and the other organic solvent, and contains more than 0% by mass of the other organic solvent to 10% It is preferable to contain less than%.

  The other organic solvent may be a fluorinated organic solvent other than the fluorinated solvent (S), or may be a non-fluorinated organic solvent containing no fluorine atom, and a non-fluorinated organic solvent is preferred. The boiling point of the other organic solvent is preferably 60 to 160 ° C.

Specific examples of the fluorinated organic solvent other than the fluorinated solvent (S) include hydrochlorofluorocarbon solvents such as CCl ₂ FCH ₃ , CF ₃ CF ₂ CHCl ₂ , and CClF ₂ CF ₂ CHClF; hydrofluoroketone solvents; CHF hydrofluoroether alcohol solvents such as ₂ CF ₂ CH ₂ OH and the like.

  Specific examples of non-fluorinated organic solvents include 1-propanol, isopropanol, n-propanol, n-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, n- Hexanol, cyclohexanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-1-pentanol, 2-methyl- 2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol 4-methyl-2-pentanol, 2,2-dimethyl-3-pentanol, 2,3-dimethyl-3-pentanol, 2,4 Dimethyl-3-pentanol, 4,4-dimethyl-2-pentanol, 3-ethyl-3-pentanol, 1-heptanol, 2-heptanol, 3-heptanol, 2-methyl-2-hexanol, 2-methyl -3-hexanol, 5-methyl-1-hexanol, 5-methyl-2-hexanol, 2-ethyl-1-hexanol, 4-methyl-3-heptanol, 6-methyl-2-heptanol, 1-octanol, 2-octanol, 3-octanol, 2-propyl-1-pentanol, 2,4,4-trimethyl-1-pentanol, 2,6-dimethyl-4-heptanol, 3-ethyl-2,2-dimethyl- Pentanol, 1-nonanol, 2-nonanol, 3,5,5-trimethyl-1-hexanol, 1-decanol, 2-decane , 4-decanol, 3,7-dimethyl-1-octanol, hydrocarbon alcohols such as 3,7-dimethyl-2-octanol; acetone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-heptanone, Hydrocarbon ketones such as N-methylpyrrolidone and γ-butyrolactone; propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether acetate, carbitol acetate, methyl 3-methoxypropionate, 3-ethoxy Ethyl propionate, methyl β-methoxyisobutyrate, ethyl butyrate, propyl butyrate, methyl isobutyl ketone, ethyl acetate, 2-ethoxyethyl acetate, isoamyl acetate, methyl lactate, ethyl lactate, etc. Hydrogenated esters; aromatic hydrocarbons such as toluene and xylene; propylene glycol methyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, etc. And hydrocarbon-based amides such as N, N-dimethylformamide and N, N-dimethylacetamide.

  The non-fluorinated organic solvent is preferably a monovalent alcohol, particularly preferably a monovalent alcohol having 4 to 8 carbon atoms, and n-butanol, 2-methyl-1-propanol, or 4-methyl-2-pentanol. Particularly preferred.

  The present invention is a method for forming a resist pattern by an immersion lithography method, the step of forming a photosensitive resist layer containing a resist polymer (R) on the surface of a substrate, on the surface of the photosensitive resist layer, A step of applying the resist protective film forming composition of the present invention, further removing the solvent to form a resist protective film layer on the surface of the photosensitive resist layer, an immersion lithography step, and a step of developing the photosensitive resist layer A resist pattern forming method for obtaining a base material on which a resist pattern is formed is provided in this order.

  A base material is not specifically limited, A silicon wafer is mentioned. The substrate may be a substrate surface-treated with an antireflection film or the like.

The method for forming the photosensitive resist layer is not particularly limited. For example, a positive photosensitive resist forming composition obtained by dissolving a resist polymer (R) and a photoacid generator in an organic solvent is coated on a desired substrate and then heated to remove the organic solvent. By removing, a photosensitive resist layer can be formed on the surface of the substrate.
Examples of the method for applying the photosensitive resist composition include a roll coating method, a casting method, a dip method, a spin coating method, a water casting method, a die coating method, and a Langmuir-Blodgett method. Heating is performed until the organic solvent is distilled off at a temperature equal to or higher than the boiling point of the organic solvent, and is usually performed at 80 to 130 ° C. for 60 to 90 seconds.

  The method for applying the resist protective film-forming composition of the present invention to the surface of the photosensitive resist layer is not particularly limited. Examples of the method for applying the resist protective film forming composition of the present invention include a roll coating method, a casting method, a dip method, a spin coating method, a water casting method, a die coating method, and a Langmuir-Blodgett method. The solvent is removed by heat drying until the solvent is distilled off at a temperature equal to or higher than the boiling point of the solvent. Usually, heat drying is performed at 80 to 130 ° C. for 60 to 90 seconds.

  In the immersion lithography process, a fine pattern image obtained by irradiating a mask having a desired fine pattern with exposure light source light is filled with an immersion liquid between the projection lens and the resist protective film layer via the projection lens. If it is the process of projecting to the desired position of a base material, moving a projection lens, it will not specifically limit.

The exposure light source light is preferably g-line (wavelength 436 nm), i-line (wavelength 365 nm), KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm) or F ₂ excimer laser light (wavelength 157 nm). Excimer laser light or F ₂ excimer laser light is more preferable, and ArF excimer laser light is particularly preferable.
The immersion liquid is not particularly limited as long as it has a high light transmittance and a high refractive index with respect to the exposure light source light.

The light transmittance of the immersion liquid is preferably 70% or more at the wavelength of the exposure light source light. However, the light transmittance means the light transmittance per 1 mm of the optical path length in the immersion liquid of the exposure light source light.
The refractive index of the immersion liquid is preferably more than 1.0 in the wavelength light of the exposure light source. The upper limit of the refractive index is not particularly limited, and is preferably 2.0 or less.

The immersion liquid may be an aqueous liquid medium or a non-aqueous liquid medium.
The aqueous liquid medium is preferably ultrapure water.
The non-aqueous liquid medium is preferably an alicyclic compound or an organosiloxane compound, and particularly preferably an alicyclic compound.
Specific examples of the non-aqueous liquid medium include cis-decalin, trans-decalin, spiro [5,5] undecane, exo-tetrahydrodicyclopentadiene, 5-silacyclo [4,4] nonane, 1-ethyladamantane, 1, Examples include 1,1-tricycloheptylmethane, dicyclohexyl, isopropylcyclohexane, cyclooctane, cycloheptane, and hexamethyldisiloxane.

  The step of developing the photosensitive resist layer is performed until an alkaline solution is brought into contact from the resist protective film layer side to remove the resist protective film layer and the exposed portion of the photosensitive resist layer.

As a specific example of the alkaline solution, an alkaline aqueous solution containing an alkaline compound selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide and triethylamine is used.
In the formation method of the present invention, a baking step and a rinsing step may be further combined.

  The present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

  In the examples, the gel permeation chromatography method is the GPC method, the weight average molecular weight is Mw, the number average molecular weight is Mn, dichloropentafluoropropane is R225, diisopropyl peroxydicarbonate is IPP, and propylene glycol methyl ether. Acetate is described as PGMEA, tetrahydrofuran as THF, methyl ethyl ketone as MEK, cyclopentanone as CP, and tetramethylammonium hydroxide as TMAH.

[Example 1] Production example of resist polymer (R) [Example 1-1] Production example of polymer (R ¹ ) The following compound (r ¹ ) (10.4 g) and the following compound (q ¹ ) were added to a reactor. (3.7 g), the following compound (p ¹ ) (8.0 g), and MEK (76.5 g) were charged. Next, isopropanol (6.3 g) was used as a chain transfer agent, and IPP (11.0 g) diluted to 50% by mass with R225 was charged as a polymerization initiator. After the inside of the reactor was frozen and degassed, a polymerization reaction was carried out at 40 ° C. for 18 hours.

After the polymerization reaction, the solution in the reactor was dropped into hexane to recover the aggregated solid, and the solid was vacuum-dried at 90 ° C. for 24 hours to obtain a resist polymer containing no fluorine atom; The union (R ¹ ) (15.9 g) was obtained.

The polymer (R ¹ ) was a white powdery amorphous polymer at 25 ° C. Mn of the polymer (R ¹ ) was 2870, and Mw was 6600. As a result of measurement by ¹³ C-NMR method, polymer (R ¹ ) was found to contain 40 mol% of repeating units of compound (r ¹ ) and 40 mol% of repeating units of compound (q ¹ ) with respect to all repeating units. And a polymer containing 20 mol% of the repeating unit of the compound (p ¹ ).
The polymer (R ¹ ) was soluble in THF, PGMEA, and CP, respectively.

[Example 1-2] Production example of polymer (R ² ) In the same manner as in Example 1-1 except that the amount of the compound and the polymerization conditions were finely adjusted, the repeating unit of compound (r ¹ ) was 37 mol%, the compound A polymer (R ² ) having Mw7100 containing 43 mol% of the repeating unit of (q ¹ ) and 20 mol% of the repeating unit of the compound (p ¹ ) was obtained.

[Example 2] Evaluation Example of solvent solubility of the resist polymer [Example 2-1] in a solvent soluble Evaluation Example silicon wafer of the polymer ^{(R 1),} spin-coated PGMEA solution containing a polymer ^{(R 1)} Then, heating was performed at 100 ° C. for 90 seconds to obtain a silicon wafer having a polymer (R ¹ ) thin film (thickness 150 nm) formed on the surface.

  The film reduction rate after 1.5 hours and the film reduction rate after 18 hours when the silicon wafer was immersed in various solvents shown in Table 1 were measured. The measurement was performed using F20 manufactured by Filmetrics. The results are summarized in Table 1.

_However, C ₅ H 3 _{F 7} are the following compounds.

[Example 2-2] was dissolved polymer ^{(R 2)} a solvent soluble Evaluation Examples 90 wt% of PGMEA and the polymer in a mixed solvent containing 10 mass% of CP of ^{(R 2),} of 10 mass% heavy A resin solution containing the union (R ² ) was obtained. The resin solution is spin-coated on a silicon wafer and heated on a hot plate at 100 ° C. for 90 seconds to form a thin film (unit: nm) of a polymer (R ² ) having a predetermined initial film thickness on the surface. A silicon wafer was obtained.

  The thickness of the thin film after the silicon wafer thin film was brought into contact with various solvents shown in Table 2 below for a predetermined time and the solvent was purged was measured. The results are summarized in Table 2.

  From the above results, it can be seen that the resist polymer (R) containing no fluorine atom is not easily modified by a fluorine-based solvent (S) such as 1,3-bis (trifluoromethyl) benzene.

[Example 3] Production example of fluoropolymer [Example 3-1] Production example of polymer (F ¹ ) CF ₂ = CFCH ₂ CH (C (CF ₃ ) ₂ OH) CH ₂ CH = CH ₂ ; Compound ( b1 ¹ ) was subjected to cyclopolymerization to obtain a fluorinated polymer having a Mw of 11000 comprising the following repeating units (B ^U1 ); a polymer (F ¹ ).

[Example 4] Production example of resist protective film forming composition [Example 4-1] Production example of composition (1) 99.5% by mass of 1,3-bis (trifluoromethyl) benzene and 2-methyl-1 2. A solution obtained by dissolving the polymer (F ¹ ) in a mixed solvent containing 0.5% by mass of propanol was filtered through a filter (manufactured by PTFE) having a pore size of 0.2 μm. A mixed solvent solution containing 5% by mass of the polymer (F ¹ ); a composition (1) was obtained.

[Example 4-2] Production Example of Composition (2) The mixed solvent in Example 4-1 was mixed with 95.1% by mass of 1,3-bis (trifluoromethyl) benzene and 4 of 2-methyl-1-propanol. A mixed solvent containing 4.5% by mass of the polymer (F ¹ ) was obtained in the same manner except that the mixed solvent containing 0.9% by mass was changed.

The mixed solvent (2.097 g) was mixed with a 1,3-bis (trifluoromethyl) benzene solution (1.366 g) containing 0.38% by mass of a homopolymer of the following compound (f11 ¹ ) to obtain a pore size. The solution was filtered through a 0.2 μm filter (manufactured by PTFE) to obtain a solution containing 6.0% by mass of the homopolymer based on the polymer (F ¹ ); composition (2) was obtained.

[Example 4-3 (Comparative Example)] Production Example of Composition (X) A solution obtained by dissolving the polymer (F ¹ ) in 2-methyl-1-propanol was used as a filter (PTFE) having a pore size of 0.2 μm. The resin solution of 2-methyl-1-propanol containing 3.5% by mass of the polymer (F ¹ ); composition (X) was obtained.

[Example 5] Intermixing evaluation example of resist protective film forming composition A resin solution containing a polymer (R ² ) was spin-coated on a silicon wafer, and then heated at 100 ° C for 90 seconds to polymer on the surface. A silicon wafer on which a thin film having a predetermined initial film thickness (unit: nm) of (R ² ) was formed was obtained.
The composition (2) is spin-coated on the surface of the thin film, and then heated at 100 ° C. for 90 seconds to form a silicon wafer, a polymer (R ² ) thin film, and a polymer (F ¹ ) thin film. Silicon wafers formed in order were obtained.
The silicon wafer is dipped in an alkaline aqueous solution containing 2.38% by mass of TMAH for 60 seconds and rinsed with ultrapure water for 10 seconds to remove the polymer (F ¹ ) thin film (R ² ) Was measured. Also, changes were observed in the thin film surface of the polymer (F ¹⁾ polymer after removal of the thin film of (R ^2). In addition, it measured similarly using the composition (X) instead of the composition (2). The results are summarized in Table 3.

[Example 6] Example of resist pattern formation Polymer (R ¹ ) (1 g) and photoacid generator triphenylsulfonium triflate (0.05 g) were dissolved in PGMEA (10 mL), and the pore size was 0.2 μm. The mixture was filtered through a filter (manufactured by PTFE) to obtain a photosensitive resist composition.

  After the photosensitive resist composition was spin-coated on the surface of a silicon wafer on which an antireflection film (trade name AR26 manufactured by ROHM AHD HAAS Electronic Materials) was formed on the surface, it was heated at 100 ° C. for 90 seconds and further to 130 ° C. For 120 seconds to obtain a silicon wafer having a photosensitive resist layer (thickness 150 nm) formed on the surface.

Furthermore, after spin-coating the composition (1) on the surface of the photosensitive resist layer of the silicon wafer, it was heat-treated at 100 ° C. for 90 seconds to form a substrate, the photosensitive resist layer, and the polymer (F A silicon wafer having a resist protective film layer made of ¹ ) formed in this order was obtained.

  A 90 nm L / S exposure test of the silicon wafer was performed by an immersion lithography process (immersion liquid: ultrapure water) using a two-beam interference exposure apparatus (light source: laser light having a wavelength of 193 nm). Subsequently, the silicon wafer was heated at 130 ° C. for 60 seconds. Furthermore, the photosensitive resist layer of the silicon wafer was developed using an alkaline aqueous solution containing 2.38% by mass of TMAH at 23 ° C. to obtain a silicon wafer on which a resist pattern formed from the photosensitive resist layer was formed. .

  A silicon wafer on which a resist pattern was formed was obtained in the same manner except that the composition (X) was used instead of the composition (1). Table 4 summarizes the results of confirming the shape of the resist pattern formed on each silicon wafer by SEM images.

From the above results, the alkali-soluble resist protective film material (polymer (F ¹ ) etc.) containing the fluoropolymer (F) and the fluorine-based solvent (S) (1,3-bis (trifluoro) A resist protective film formed from a resist-forming protective film composition containing (methyl) benzene etc.) is formed on the surface of the photosensitive resist layer containing the resist polymer (R) (polymer (R ¹ ) etc.). It can be seen that a resist pattern with high shape accuracy can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the stable resist protective film formation composition which enables high-speed implementation of the immersion lithography method which can form a highly accurate resist pattern is provided.

Claims (6)

A resist protective film forming composition used by being applied to the surface of the following photosensitive resist layer, comprising the following resist protective film material and the following solvent.
Photosensitive resist layer: A layer containing a resist polymer (R) which is a polymer whose alkali solubility is increased by the action of an acid and has a lower fluorine content than the fluoropolymer (F).
Resist protective film material: An alkali-soluble material containing a fluoropolymer (F).
Solvent: A solvent containing at least one fluorine-based solvent (S) selected from hydrofluorocarbon solvents and hydrofluoroether solvents.   The resist protective film-forming composition according to claim 1, wherein the resist polymer (R) is a resist polymer containing no fluorine atom. The resist protective film material is formed by polymerization of a monomer (b ^M ) having at least one functional group selected from a hydroxy group, a carboxy group, a sulfonic acid group, a sulfonylamide group, an amino group, and a phosphoric acid group. repeating comprises units (B ^U), alkali solubility of the fluorine-containing polymer containing (F ^P), the resist protective film forming composition according to claim 1 or 2.   The resist protective film formation composition in any one of Claims 1-3 whose solvent is a mixed solvent containing the fluorine-type solvent (S) and the organic solvent which does not contain a fluorine atom.   The resist protective film formation composition in any one of Claims 1-4 whose fluorine-type solvent (S) is 1, 3-bis (trifluoromethyl) benzene. A resist pattern forming method by immersion lithography, which is a polymer whose alkali solubility is increased by the action of an acid on the surface of a substrate and has a lower fluorine content than the fluoropolymer (F) ( R), a step of forming a photosensitive resist layer, a resist protective film forming composition containing the following resist protective film material and the following solvent is applied to the surface of the photosensitive resist layer, and the solvent is removed: A resist pattern for obtaining a base material on which a resist pattern is formed by performing a step of forming a resist protective film layer on the surface of the photosensitive resist layer, an immersion lithography step, and a step of developing the photosensitive resist layer in this order. Forming method.
Resist protective film material: a material containing an alkali-soluble fluoropolymer (F).
Solvent: A solvent containing at least one fluorine-based solvent (S) selected from hydrofluorocarbon solvents and hydrofluoroether solvents.