JP2008032758A - Resist protective film composition for immersion exposure and method for forming resist pattern - Google Patents

Abstract

A resist protective film composition for immersion exposure is provided.
CF ₂ ═CF—CH ₂ CHR (CH ₂ ) _m —CH═CH _{2, wherein} R is an alkyl group having 1 to 12 carbon atoms or a fluoroalkyl group having 1 to 12 carbon atoms, m is 0, 1 Or a polymer containing a repeating unit (A) formed by polymerization such as 2), wherein the polymer (A) contains 10 mol% or more of the repeating unit (A) with respect to all repeating units; , An alkali-soluble polymer (B) containing a repeating unit formed by polymerization of a polymerizable monomer (b) having a polar group such as a hydroxy group or a carboxy group, and the polymer (B) A resist protective film composition for immersion exposure comprising 0.1 to 30% by mass of the polymer (A).
[Selection figure] None

Description

  The present invention relates to a resist protective film composition for immersion exposure 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 pattern image is projected onto a desired position of the photosensitive resist through a projection lens that moves relatively on the photosensitive resist.

  Furthermore, in recent years, an exposure process using a phenomenon in which the wavelength of light in a liquid medium is a reciprocal of the refractive index of the liquid medium, that is, a liquid medium (water or the like) between the lower portion of the projection lens and the upper portion of the photosensitive resist. In addition, an immersion lithography method including an immersion exposure process in which a pattern image of a mask is projected onto a photosensitive resist on a substrate through a projection lens is being studied.

  However, in the immersion exposure process, since the space between the projection lens and the photosensitive resist is filled with water, components (photoacid generator, etc.) in the photosensitive resist are eluted in the water, and water is in the photosensitive resist. And the photosensitive resist swells. Therefore, an attempt is made to provide a resist protective film on the photosensitive resist to suppress elution of the photosensitive resist into water, water intrusion into the photosensitive resist, and the like.

As a resist protective film, an alkali-soluble polymer containing a repeating unit formed by polymerization of a polymerizable monomer having a polar group (for example, a compound represented by the following formula (g1)) and a fluorosurfactant And a resist protective film containing the following formula (see Patent Document 1) and the following formula formed by polymerization of a compound represented by the formula CF ₂ = CFCF ₂ C (CF ₃ ) (OR ^g ) CH ₂ CH═CH ₂ ( A resist protective film (see Patent Document 2) made of a polymer containing a repeating unit represented by G2) is known. However, ^Rg shows a hydrogen atom or a C1-C15 alkyloxy group or alkyloxyalkyl group.

JP 2005-352384 A JP 2005-264131 A

  When forming a resist protective film on the photosensitive resist in the immersion exposure process, it is desirable to select the resist protective film so that water follows the projection lens that moves relatively on the resist protective film. .

  However, the fluorosurfactant disclosed in the resist protective film of Patent Document 1 is a polymer formed by polymerization of a non-polymeric linear fluorine-containing compound and a (meth) acrylate having a linear fluoroalkyl group. Stay united. Therefore, the dynamic water repellency of the resist protective film is not sufficiently high. Therefore, when the resist protective film is used as a resist protective film for immersion exposure, it is considered that water does not sufficiently follow the projection lens that moves at high speed on the resist protective film, and the immersion exposure process cannot be stably performed. The dynamic water repellency of the resist protective film of Patent Document 2 is still not sufficient.

  The present inventors have excellent immersion resist protective film characteristics (suppression of swelling of the photosensitive resist due to intrusion of water, suppression of elution of the photosensitive resist component into the liquid medium, etc.) and particularly excellent dynamic water repellency. In order to obtain a resist protective film that slides well in water, intensive studies were conducted. As a result, a resist protective film having excellent physical properties was found.

That is, the present invention provides the following inventions.
[1] A resist protective film for immersion exposure comprising the following polymer (A) and the following polymer (B), and 0.1 to 30% by mass of the polymer (A) with respect to the polymer (B). Composition.
Polymer (A): a repeating unit (A) formed by polymerization of a compound represented by the following formula (a1), a compound represented by the following formula (a2) or a compound represented by the following formula (a3) A polymer containing 10% by mole or more of the repeating unit (A) based on all repeating units.
_{^{CF 2 = CF-Q-CX}} 1 = CX 2 X 3 (a1).

However, the symbol in a formula shows the following meaning.
Q: 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. The hydrogen atom in the group is a group selected from the group consisting of an alkyl group, a fluoroalkyl group, an alkoxy group and a fluoroalkoxy group, and may be substituted with a group having 1 to 12 carbon atoms or a fluorine atom.
X ¹ : a hydrogen atom, a fluorine atom, an alkyl group having 1 to 12 carbon atoms, or a fluoroalkyl group having 1 to 12 carbon atoms.
X ² and X ³ : each independently a hydrogen atom or a fluorine atom.
W ¹ : A fluorine atom or a C 1-3 perfluoroalkoxy group.
W ² , W ³ , W ⁴ , W ⁵ : each independently a fluorine atom or a C 1-6 perfluoroalkyl group.

  Polymer (B): formed by polymerization of a polymerizable monomer (b) having a polar group selected from the group consisting of hydroxy group, carboxy group, sulfonic acid group, sulfonylamide group, amino group and phosphoric acid group An alkali-soluble polymer containing repeating units.

[2] The polymer (A) is a polymer containing a repeating unit (A11) formed by polymerization of a compound represented by the following formula (a11), and the repeating unit (A11) is based on all repeating units. The resist protective film composition for immersion exposure according to [1], which is a polymer containing 10 mol% or more of.
_{CF 2 = CF-CH 2 CHR} (CH 2) m -CX 11 = CH 2 (a11).
However, the symbol in a formula shows the following meaning.
R: an alkyl group having 1 to 12 carbon atoms or a fluoroalkyl group having 1 to 12 carbon atoms.
m: 0, 1 or 2.
X < ¹¹ >: A hydrogen atom or a C1-C12 alkyl group.

[3] The repeating unit (A11) formed by polymerizing the compound represented by the following formula (a11) and the repeating unit formed by polymerizing the compound represented by the following formula (b1): And a polymer containing 10 mol% or more of the repeating unit (A11) and 10 mol% or more of the repeating unit (B1) with respect to all repeating units [1]. Or the resist protective film composition for immersion exposure as described in [2].
_{CF 2 = CF-CH 2 CHR} (CH 2) m -CX 11 = CH 2 (a11).
^{_{CF 2 = CF-Q b1 -CX}} b1 = CH 2 (b1).
However, the symbol in a formula shows the following meaning.
Q ^b1 : a group represented by the formula —CF ₂ C (CF ₃ ) (OH) (CH ₂ ) _n —, a formula —CH ₂ CH ((CH ₂ ) _p C (CF ₃ ) ₂ (OH)) (CH _{2) n} -, a group represented by or formula _{-CH 2 CH (C (O)} OH)) (CH 2) n - group represented by the.
n, p: each independently 0, 1 or 2.
X ^b1 : a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

[4] The resist protective film composition for immersion exposure according to any one of [1] to [3], wherein the polymerizable monomer (b) is a polymerizable monomer having a hydroxy group or a carboxy group.
[5] The polymerizable monomer (b) is a polymerizable monomer having a hydroxy group or a carboxy group bonded to a carbon atom adjacent to the carbon atom to which the polyfluoroalkyl group is bonded. 4] The resist protective film composition for immersion exposure according to any one of [4].

[6] The polymerizable monomer (b) is a compound represented by the formula (b1), a compound represented by the following formula (b2), a compound represented by the following formula (b3), or the following formula (b4). The resist protective film composition for immersion exposure according to [1] to [5], which is a compound represented by:
CH ₂ = CR ^b2 C (O) O—W ^b2 (—C (CF ₃ ) ₂ OH) _r (b2),
^{_{CH 2 = CH-W b3 (}} -C (CF 3) 2 OH) r (b3).

However, the symbol in a formula shows the following meaning.
R ^b2 : 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 ^b2 and W ^b3 : each independently a (r + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, which may contain a fluorine atom.
r: 1 or 2.
W ^b4 : a ^C 1-10 divalent hydrocarbon group that may contain a single bond or a fluorine atom.

  [7] The resist protective film composition for immersion exposure according to any one of [1] to [6], comprising an organic solvent.

  [8] A step of applying a photosensitive resist on the substrate to form a resist film on the substrate, and applying the resist protective film composition for immersion exposure on the resist film according to [7] to the resist film A method for forming a resist pattern, wherein a resist pattern is formed on a substrate by sequentially performing a step of forming a resist protective film on the film, an immersion exposure step, and a development step.

  According to the present invention, it is excellent in immersion resist protective film properties (suppression of swelling of the photosensitive resist due to water intrusion, suppression of elution of the photosensitive resist component into the liquid medium, etc.) and particularly excellent in dynamic water repellency. A resist protective film composition for immersion exposure is provided. By using the resist protective film composition for immersion exposure of the present invention, an immersion lithography method capable of transferring a mask pattern image with high resolution can be stably performed.

  In this specification, the compound represented by formula (a) is also referred to as compound (a), and the repeating unit represented by formula (A) is also referred to as unit (A). Compounds represented by other formulas and repeating units are also described in the same manner. Further, symbols in the group are as defined above unless otherwise specified.

The resist protective film composition for immersion exposure of the present invention (hereinafter also referred to as protective film composition) is a repeating unit formed by polymerization of the following compound (a1), the following compound (a2) or the following compound (a3). It is a polymer containing (A), Comprising: The polymer (A) which contains 10 mol% or more of repeating units (A) with respect to all the repeating units is included.
_{^{CF 2 = CF-Q-CX}} 1 = CX 2 X 3 (a1).

The polymer (A) is excellent in water repellency and particularly excellent in dynamic water repellency. The reason is not necessarily clear, but the polymer (A) is a polymer having a bulky fluorine-containing ring structure in the main chain, that is, the polymer formed by the polymerization of the compound (a1) has the following units ( A polymer comprising any one of A1 ¹ ) to (A1 ³ ), and the polymer formed by polymerizing the compound (a2) is a polymer comprising the following unit (A2), and by polymerizing the compound (a3) This is probably because the polymer formed is a polymer containing the following unit (A3).

  Therefore, when the protective film composition of the present invention containing the polymer (A) is a resist protective film for immersion exposure that has high water repellency, is difficult to enter water, and is particularly excellent in dynamic water repellency, it slides well in water. Conceivable.

  As the compound (a), one type of compound (a) may be used, or two or more types of compounds (a) may be used.

Q of the compound (a1) is preferably a group selected from the group consisting of a trimethylene group, a tetramethylene group and an oxydimethylene group. The hydrogen atom in the group is a group selected from the group consisting of an alkyl group and a fluoroalkyl group, and is preferably substituted with a group having 1 to 12 carbon atoms or a fluorine atom.
Q is —CF ₂ CF ₂ CH ₂ —, a group represented by the formula —CFR ^F CF ₂ CH ₂ —, a group represented by the formula —CF ₂ CFR ^F CH ₂ —, or a formula —CH ₂ CHRCH ₂ —. A group represented by the formula: -OCF ₂ CF _2- , a group represented by the formula -OCF ₂ CFR ^F- or a group represented by the formula -OCFR ^F CF _2- is preferred, and is represented by the formula -CH ₂ CHRCH _2-. Are particularly preferred. However, ^{R F} is a perfluoroalkyl group having 1 to 6 carbon atoms, shown.

X ¹ of the compound (a1) is preferably a hydrogen atom or a fluorine atom.

Specific examples of the compound (a1) (excluding the compound (a11) described later) include the following compounds.
_{CF 2 = CFCF 2 CF 2 CH} 2 CH = CH 2,
_{CF 2 = CFCF (CF 3)} CF 2 CH 2 CH = CH 2,
_{CF 2 = CFCF 2 CF (CF} 3) CH 2 CH = CH 2,
CF ₂ = CFOCF ₂ CF ₂ CF = CF ₂ ,
CF ₂ = CFOCF (CF ₃ ) CF ₂ CF = CF ₂ ,
CF ₂ = CFOCF ₂ CF (CF ₃ ) CF═CF ₂ ,
CF ₂ = CFOCF ₂ CF ₂ CH═CF ₂ ,
CF ₂ = CFOCF (CF ₃ ) CF ₂ CH═CF ₂ ,
CF ₂ = CFOCF ₂ CF (CF ₃ ) CH═CF ₂ ,
CF ₂ = CFOCF ₂ CF ₂ CH═CH ₂ ,
CF ₂ = CFOCF (CF ₃ ) CF ₂ CH═CH ₂ ,
_{CF 2 = CFOCF 2 CF (CF} 3) CH = CH 2.

  Specific examples of the compound (a2) include the following compounds.

  Specific examples of the compound (a3) include the following compounds.

  The compound (a) is preferably a compound having a hydrogen atom bonded to a carbon atom from the viewpoint of compatibility with the polymer (B).

The compound (a) is preferably the following compound (a11).
_{CF 2 = CF-CH 2 CHR} (CH 2) m -CX 11 = CH 2 (a11).
R is preferably a C 1-6 alkyl group or a C 1-6 polyfluoroalkyl group.
m is preferably 1.
X ¹¹ is preferably a hydrogen atom.

Specific examples of the compound (a11) include the following compounds.
_{CF 2 = CFCH 2 CH (CH} 2 CH 3) CH 2 CH = CH 2,
CF ₂ ═CFCH ₂ CH ((CH ₂ ) ₃ CH ₃ ) CH ₂ CH═CH ₂ ,
_{CF 2 = CFCH 2 CH (CH} 2 CH (CH 3) 2) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH ((} CH 2) 5 CH 3) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (CH} 2 CF 3) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (CH} 2 CF 2 CF 3) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (CH} 2 (CF 2) 2 CF 3) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (CH} 2 CF (CF 3) 2) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (CH} 2 (CF 2) 3 CF 3) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (CF} 3) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (CF} 2 CF 3) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH ((} CF 2) 3 CF 3) CH 2 CH = CH 2.

Compound (a11) is a novel compound unknown in the literature. Compound (a11) is obtained by reacting a compound represented by the formula CH ₂ ═CHR with CF ₂ ClCFClI to obtain the following compound (pa31). Next, compound (pa31) and CH ₂ ═CX ¹¹ (CH ₂ ) _m It can be produced by reacting MgCl to obtain the following compound (pa21) and then dechlorinating the compound (pa21) in the presence of Zn.
CF ₂ ClCFCl—CH ₂ CHIR (pa31),
_{CF 2 ClCFCl-CH 2 CHR (} CH 2) m -CX 11 = CH 2 (pa21).

  The polymer (A) is preferably a polymer having a hydrogen atom fluorine atom bonded to a carbon atom from the viewpoint of compatibility with the polymer (B).

  A polymer (A) contains 10 mol% or more of units (A) with respect to all the repeating units. The unit (A) may consist of only one type of unit (A) or may consist of two or more types of units (A).

  The polymer (A) may be a polymer comprising only the unit (A), or a polymer comprising the unit (A) and a repeating unit other than the unit (A) (hereinafter also referred to as other units). It may be. In any case, the polymer (A) contains 10 mol% or more and preferably 30 mol% or more of the unit (A) with respect to all repeating units. When the polymer (A) contains other units, the polymer (A) preferably contains 90 mol% or less, particularly preferably 70 mol% or less, based on all repeating units. .

The other unit is preferably a repeating unit (B1) formed by polymerization of the following compound (b1).
_{^{CF 2 = CF-Q b1 -CX}} b1 = CH 2 (b1).

  The compound (b1) forms any repeating unit represented by the following formula by polymerization. Therefore, the protective film composition of the present invention comprising the polymer (A) containing the unit (B1) has a high water repellency and is difficult to penetrate into water, and has a particularly excellent dynamic water repellency and slides well in water. It is thought that it becomes.

The unit (B1) includes a ^Qb1 moiety (—CF ₂ C (CF ₃ ) (OH) (CH ₂ ) _n — moiety, —CH ₂ CH ((CH ₂ ) _p C (CF ₃ ) ₂ (OH) _{) (CH} 2) _n - moiety or _{-CH 2 CH (C (O)} OH)) (CH 2) n - moiety. ), It is alkalophilic. Therefore, in the case where the protective film composition of the present invention containing the polymer (A) containing the unit (A) and the unit (B1) is used, the immersion exposure process can be stably performed, and the resist with an alkaline solution in the development process can be used. An immersion lithography method capable of removing the protective film is realized.

X ^b1 in the compound (b1) is preferably a hydrogen atom.
As for n in Q ^b1 of a compound (b1), 1 is especially preferable.
P in Q ^b1 of the compound (b1) is preferably 0 or 1.
Q ^b1 of the compound (b1) is —CF ₂ C (CF ₃ ) (OH) CH ₂ —, —CH ₂ CH (C (CF ₃ ) ₂ (OH)) CH ₂ — or —CH ₂ CH (C ( O) OH)) CH ₂ - is preferred.

Specific examples of the compound (b1) include the following compounds.
_{CF 2 = CFCF 2 C (CF} 3) (OH) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (C} (CF 3) 2 (OH)) CH 2 CH = CH 2,
_{CF 2 = CFCH 2 CH (C} (O) OH) CH 2 CH = CH 2.

  Examples of the unit other than the unit (B1) include a repeating unit formed by polymerization of a compound (b2), a compound (b3), or a compound (b4), which will be described later.

  1000-30000 are preferable and, as for the weight average molecular weight of a polymer (A), 1000-10000 are especially preferable.

  In a preferred embodiment of the polymer (A) in the present invention, a polymer composed only of the repeating unit (A11) formed by polymerization of the compound (a11), a polymer containing the repeating unit (A11) and the repeating unit (B1). Examples of the polymer include a polymer containing 10 mol% or more of the repeating unit (A11) and 10 mol% or more of the repeating unit (B1) with respect to all repeating units. The latter polymer preferably contains 10 to 70 mol% of the repeating unit (A11) and 10 to 90 mol% of the repeating unit (B1) with respect to all repeating units. Moreover, as for the weight average molecular weight of the polymer (A) in the said aspect, 5000-30000 are preferable.

  The protective film composition of the present invention is obtained by polymerizing a polymerizable monomer (b) having a polar group selected from the group consisting of a hydroxy group, a carboxy group, a sulfonic acid group, a sulfonylamide group, an amino group, and a phosphoric acid group. An alkali-soluble polymer (that is, polymer (B)) containing the formed repeating unit (hereinafter also referred to as unit (b)) is included. Since the polymer (B) interacts with the alkali and dissolves in the alkaline solution, the protective film composition of the present invention can be easily removed with the alkaline solution.

  The polymerizable monomer (b) is preferably a polymerizable monomer having a hydroxy group or a carboxy group. The hydroxy group may be an alcoholic hydroxy group or a phenolic hydroxy group.

From the viewpoint of the water repellency of the polymer (B) and the hydrophilicity of the polymer (B), the polymerizable monomer (b) is bonded to the carbon atom adjacent to the carbon atom to which the polyfluoroalkyl group is bonded. A polymerizable monomer having a bonded hydroxy group or carboxy group is more preferable, and a group represented by the formula —C (C _d F _{2d + 1} ) (OH) —, a formula —C (C _d F _{2d + 1} ) ₂ (OH ) Or a carboxy group-containing polymerizable monomer (where d represents an integer of 1 to 6), -C (CF ₃ ) (OH)-, -C (CF ₃ ) ₂ (OH) or a polymerizable monomer having a carboxy group is most preferred.

The polymerizable monomer (b) is preferably the compound (b1), the following compound (b2), the following compound (b3) or the following compound (b4), and particularly preferably the compound (b1).
CH ₂ = CR ^b2 C (O) O—W ^b2 (—C (CF ₃ ) ₂ OH) _r (b2),
^{_{CH 2 = CH-W b3 (}} -C (CF 3) 2 OH) r (b3).

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

When W ^b2 of the compound (b2) and W ^b3 of the compound (b3) are (r + 1) -valent hydrocarbon groups having 1 to 20 carbon atoms that may contain a fluorine atom, W ^b2 and W ^b3 are These are each independently preferably an (r + 1) -valent hydrocarbon group having 1 to 20 carbon atoms which may contain a fluorine atom having a ring hydrocarbon group. In this case, the (r + 1) -valent hydrocarbon group may be a group consisting of only a ring hydrocarbon group or a group containing a ring 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 condensed polycyclic hydrocarbon group or a bridged ring hydrocarbon group.

W ^b2 of compound (b2) and W ^b3 of compound (b3) are particularly preferably any group represented by the following formula.

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

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

W ⁴ of the compound (b4) is preferably a single bond or a methylene group.
Specific examples of the compound (b4) include the following compounds.

  The polymer (B) in the present invention preferably contains 10 mol% or more, particularly preferably 50 mol% or more of the unit (b) with respect to all repeating units. The polymer (B) may be a polymer composed only of the unit (b), and includes the unit (b) and a repeating unit other than the unit (b) (hereinafter also referred to as other unit (b)). It may be a polymer containing. The unit (b) may consist of only one type of unit (b) or may consist of two or more types of units (b). When the polymer (B) contains other units (b), the polymer (A) preferably contains 90 mol% or less, and 50 mol% or less of the other units (b) with respect to all repeating units. It is particularly preferable to include it.

  Examples of the other unit (b) include repeating units formed by polymerization of the following compounds.

  1000-100000 are preferable and, as for the weight average molecular weight of the polymer (B) in this invention, 1000-50000 are especially preferable.

  A preferred embodiment of the polymer (B) in the present invention is a polymer containing 70 to 100 mol% of repeating units formed by polymerization of the compound (b1) with respect to all repeating units, and having a weight average molecular weight. Examples include 1000 to 100,000 polymers. As a more preferred embodiment, a polymer having a weight average molecular weight of 1000 to 50000 consisting only of repeating units formed by cyclopolymerization of the compound (b1) can be mentioned.

  The protective film composition of this invention contains a polymer (A) and a polymer (B), and contains 0.1-30 mass% of polymers (A) with respect to a polymer (B). More preferably, 1-10 mass% of polymers (A) are included with respect to a polymer (B). In this case, there is an effect that the polymer (A) and the polymer (B) are easily compatible with each other, and the film forming property of the protective film composition is excellent.

The protective film composition of this invention may contain components (henceforth other components) other than a polymer (A) and a polymer (B). Examples of other components include organic solvents, plasticizers, stabilizers, colorants, and antihalation agents.
Since the protective film composition of the present invention is usually used by being applied to a resist film formed on a substrate (silicon wafer or the like) to form a film, it is prepared in a liquid form from the viewpoint of film forming properties. Is preferred. The protective film composition of the present invention preferably contains an organic solvent.

An organic solvent will not be specifically limited if it is a solvent with high compatibility with respect to a polymer (A) and a polymer (B). 1 type may be used for an organic solvent and 2 or more types may be used for it.
Specific examples of the organic solvent include a fluorine-containing organic solvent composed of a fluorine-containing compound and an organic solvent composed of a compound not containing a fluorine atom.

Specific examples of the fluorine-containing compound include hydrochlorofluorocarbons such as CCl ₂ FCH ₃ , CF ₃ CF ₂ CHCl ₂ , and CClF ₂ CF ₂ CHClF; CF ₃ CHFCHFCF ₂ CF ₃ , CF ₃ (CF ₂ ) ₅ H, Hydrofluorocarbons such as CF ₃ (CF ₂ ) ₃ C ₂ H ₅ , CF ₃ (CF ₂ ) ₅ C ₂ H ₅ , CF ₃ (CF ₂ ) ₇ C ₂ H ₅ ; 1,3-bis (trifluoromethyl) ) Hydrofluorobenzenes such as benzene and meta-xylene hexafluoride; Hydrofluoroketones; Hydrofluoroalkylbenzenes; CF ₃ CF ₂ CF ₂ CF ₂ OCH ₃ , (CF ₃ ) ₂ CF—CF (CF ₃ ) CF ₂ Hydrofluorocarbons such as OCH ₃ and CF ₃ CH ₂ OCF ₂ CHF ₂ Tellurium; Hydrofluoroalcohols such as CHF ₂ CF ₂ CH ₂ OH are listed.

  Specific examples of the compound containing no fluorine atom include methyl alcohol, ethyl alcohol, diacetone alcohol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-ethylbutanol, and pentanol. , Alcohols such as hexanol and heptanol, acetone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, ketones such as 2-heptanone, N-methylpyrrolidone and γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propio Nate, propylene glycol monoethyl ether acetate, carbitol acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, β-methoxyisobutyric acid Methyl, ethyl butyrate, propyl butyrate, methyl isobutyl ketone, ethyl acetate, 2-ethoxyethyl acetate, isoamyl acetate, methyl lactate, esters such as ethyl lactate, aromatic hydrocarbons such as toluene and xylene, propylene glycol monomethyl ether, propylene Glycol mono- or dialkyl ethers such as glycol methyl ether acetate, propylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, N, N-dimethylformamide, N, N-dimethylacetamide Etc.

  The protective film composition of the present invention preferably contains 100% by weight to 10,000% by weight of an organic solvent based on the total amount of the polymer (A) and the polymer (B).

  The method for producing the protective film composition of the present invention is not particularly limited, and a solution obtained by dissolving the polymer (A) in an organic solvent (hereinafter also referred to as a resin solution (A)) and the polymer (B). ) In an organic solvent (hereinafter also referred to as a resin solution (B)), a method of mixing a polymer (A) and a resin solution (B), a resin solution (A ) And the polymer (B). The resin solution (A) preferably contains 0.01 to 10% by mass of the polymer (A). The resin solution (B) preferably contains 0.1 to 20% by mass of the polymer (B).

  The protective film composition of the present invention is used in an immersion lithography method. The immersion lithography method is not particularly limited, and a step of coating a photosensitive resist on a substrate (silicon wafer or the like) to form a resist film on the substrate, the resist protective film composition for immersion exposure according to the present invention. An immersion lithography method in which a step of coating a resist film on the resist film to form a resist protective film on the resist film, an immersion exposure step, a development step, an etching step, and a resist stripping step are listed.

  The photosensitive resist in the present invention is not particularly limited as long as it is a photosensitive resist composition containing a photoacid generator and a polymer whose alkali solubility is increased by the action of an acid. Specific examples of the photosensitive resist composition include photosensitive resists described in JP-A-2005-234178. More specifically, a photosensitizer containing triphenylsulfonium triflate as a photoacid generator and a polymer each containing a repeating unit formed by polymerization of three compounds represented by the following formula as the polymer. Resist composition.

As an exposure light source in the immersion lithography method, g-line (wavelength 436 nm), i-line (wavelength 365 nm), KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F ₂ excimer laser light (wavelength 157 nm) ). The exposure light source is preferably ArF excimer laser light or F ₂ excimer laser light, particularly preferably ArF excimer laser light.

  In the immersion exposure process of the present invention, the mask pattern image obtained by irradiating the mask with light from an exposure light source is passed through a projection lens that moves relatively on the resist protective film, and the projection lens and the resist are protected. There is a step of projecting to a desired position of the resist film on the substrate while filling the space between the films with a liquid medium. The liquid medium is preferably a liquid medium containing water as a main component, and ultrapure water is particularly preferable.

  In the immersion exposure process of the present invention, the resist film is shielded from the liquid medium (water, etc.) by the protective film comprising the immersion protective film composition of the present invention, and is not easily penetrated into the liquid medium. The components in the film are difficult to elute into the liquid medium. Therefore, in the immersion exposure process of the present invention, the resist film is unlikely to swell, and optical characteristics such as the refractive index of the liquid medium are unlikely to change. Furthermore, in the immersion exposure process according to the present invention, since water follows the projection lens that moves relatively on the resist protective film, a stable immersion exposure process can be performed.

  Examples of the development step in the present invention include a step of removing the exposed portion of the resist with an alkaline solution. The alkali solution is not particularly limited, and examples thereof include an aqueous alkali solution containing an alkali compound selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, and triethylamine. In the development step in the present invention, the photosensitive portion of the resist film and the resist protective film can be removed together by alkaline solution treatment.

The present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
In the examples, the weight average molecular weight is Mw, the number average molecular weight is Mn, dichloropentafluoropropane is R225, tetrahydrofuran is THF, diisopropyl peroxydicarbonate is IPP, propylene glycol methyl ether acetate is PGMEA, I write.

  Mw and Mn were measured using gel permeation chromatography. In the measurement, THF was used as a developing solvent, and polystyrene was used as an internal standard.

The following compound (a11 ¹ ) was used as the compound (a11).
_{CF 2 = CF 2 CH 2 CH} (CH 2 CF (CF 3) 2) CH 2 CH = CH 2 (a11 1).
A repeating unit represented by the following formula (A11 ¹ ) is referred to as a unit (A11 ¹ ).

As the polymer (B), a polymer (hereinafter referred to as a repeating unit (B1 ¹ )) represented by the following formula (B1 ¹ ) obtained by homopolymerizing the following compound (b1 ¹ ) ( Mw11000) (referred to as polymer (B-1)) or a repeating unit represented by the following formula (B1 ² ) obtained by homopolymerizing the following compound (b1 ² ) (hereinafter referred to as repeating unit (B1 ² )) A polymer (Mw5000) (referred to as polymer (B-2)) was used.
_{CF 2 = CF 2 CH 2 CH} (C (CF 3) 2 OH) CH 2 CH = CH 2 (b1 1),
_{CF 2 = CF 2 CF 2 C} (CF 3) (OH) CH 2 CH = CH 2 (b1 2).

Example 1 Production Example of Compound (a11 ¹ ) CH ₂ = CH ₂ CH ₂ OCOCH ₃ (158 g) and azoisobutyronitrile (4.77 g) were placed in a reactor, and the reactor internal temperature was 65 ° C. (CF ₃ ) ₂ CFI (430 g) was added dropwise, and the inside of the reactor was further stirred. The solution in the reactor was added dropwise at 25 ° C. to a reactor containing zinc (105 g) and methanol (446 g), and the inside of the reactor was further stirred. The solution in the reactor was distilled under reduced pressure to obtain CH ₂ ═CHCH ₂ CF (CF ₃ ) ₂ (199 g).

CF ₂ ClCFClI (312 g) and azoisobutyronitrile (3.0 g) were added to the reactor, and CH ₂ = CHCH ₂ CF (CF ₃ ) ₂ (199 g) was added dropwise at a reactor internal temperature of 70 ° C. Further, the inside of the reactor was stirred. The solution in the reactor was distilled under reduced pressure to obtain CF ₂ ClCFClCH ₂ CHI (CH ₂ CF (CF ₃ ) ₂ ) (430 g).

CF ₂ ClCFClCH ₂ CHI (CH ₂ CF (CF ₃ ) ₂ ) (430 g) and THF (935 g) were placed in a reactor, and a THF solution containing CH ₂ ═CHCH ₂ MgCl at a reactor internal temperature of −70 ° C. 482 g) was added dropwise over 1 hour, and the inside of the reactor was stirred at a reactor internal temperature of 25 ° C. for 12 hours. The filtrate of the solution in the reactor was concentrated, further washed with an aqueous hydrochloric acid solution and saturated brine, and then distilled under reduced pressure to obtain CF ₂ ClCFClCH ₂ CH (CH ₂ CF (CF ₃ ) ₂ ) CH ₂ CH═CH ₂ (175 g). Obtained.

Zinc (55 g) and N-methyl-2-pyrrolidinone (310 g) were placed in the reactor, and CF ₂ ClCFClCH ₂ CH (CH ₂ CF (CF ₃ ) ₂ ) CH ₂ CH═CH at a reactor internal temperature of 75 ° C. ₂ (175 g) was added dropwise, and the reactor was further stirred. The solution in the reactor was concentrated, washed with an aqueous hydrochloric acid solution and saturated brine, and distilled under reduced pressure to obtain compound (a11 ¹ ) (92 g).

The NMR spectrum of the compound (a11 ¹ ) is shown below.
¹ H-NMR (399.8 MHz, solvent: heavy acetone, standard: tetramethylsilane) δ (ppm): 2.42 (m, 7H), 5.14 (m, 2H), 5.80 (m, 1H ).
¹⁹ F-NMR (376.2 MHz, solvent: heavy acetone, standard: CFCl ₃ ) δ (ppm): -185.1 (m, 1F), -172.3 (m, 1F), -123.7 (m , 1F), -104.9 (m, 1F), -76.5 (m, 6F).

[Example 3] Production example of polymer (A) [Example 3-1] Production example of polymer (A-1) In a pressure-resistant reactor (internal volume 30 mL, glass), compound (a11 ¹ ) (2.5 g ) And ethyl acetate (4.5 g), and an R225 solution (0.21 g) containing 50% by mass of IPP as a polymerization initiator was added. After depressurizing and depressurizing the inside of the pressure resistant reactor, a polymerization reaction was performed at a reactor internal temperature of 40 ° C. for 18 hours. Next, the solid content produced by dropping the solution in the reactor into methanol is recovered, the solid content is vacuum-dried at 90 ° C. for 24 hours, and a white powdery polymer (2. 17 g) (referred to as polymer (A-1)). The polymer (A-1) was a polymer composed of units (A11 ¹ ). Mn of the polymer (A-1) was 7300, and Mw was 15900.

  The glass transition temperature of the polymer (A-1) measured using differential scanning calorimetry was 82 ° C. Further, the polymer (A-1) was soluble in acetone, THF, ethyl acetate, R225 and xylene hexafluoride, respectively.

[Example 3-2] Production example of polymer (A-2) Compound (a11 ¹ ) (3.16 g), compound (b1 ¹ ) (2.0 g) in a pressure resistant reactor (internal volume 30 mL, glass) And R225 (19.6 g) and 2-propanol (0.67 g) were added, and an R225 solution (0.77 g) containing 50% by mass of IPP as a polymerization initiator was added. After depressurizing and depressurizing the inside of the pressure resistant reactor, a polymerization reaction was performed at a reactor internal temperature of 40 ° C. for 18 hours. Next, the solid content produced by dropping the solution in the reactor into hexane was recovered, and the solid content was vacuum-dried at 80 ° C. for 24 hours, and a white powdery polymer (4. 09 g) (referred to as polymer (A-2)). ¹⁹ F-NMR result of the measurement, the polymer (A-2), based on all repeating units comprise 60 mole percent of repeating units (A11 ^1), a polymer containing 40 mole% of recurring units (B1 ¹⁾ I confirmed that there was. Mn of the polymer (A-2) was 4500, and Mw was 9300.

  The glass transition temperature of the polymer (A-2) measured using differential scanning calorimetry was 94 ° C. The polymer (A-2) was soluble in acetone, THF, ethyl acetate, R225 and xylene hexafluoride, respectively.

[Example 3-3] Production example of polymer (A-3) In a pressure resistant reactor (internal volume 30 mL, glass), compound (a11 ¹ ) (1.61 g), compound (b1 ² ) (0.87 g) Then, methyl acetate (9.57 g) and 2-propanol (0.24 g) were added, and an R225 solution (0.373 g) containing 50% by mass of IPP as a polymerization initiator was added. After depressurizing and depressurizing the inside of the pressure resistant reactor, a polymerization reaction was performed at a reactor internal temperature of 40 ° C. for 18 hours. Next, the solid content produced by dropping the solution in the reactor into hexane was recovered, and the solid content was vacuum-dried at 100 ° C. for 24 hours, and a white powdery polymer (1. 86 g) (referred to as polymer (A-3)). ^{As a result of 19} F-NMR measurement and ¹ H-NMR measurement, polymer (A-3) contains 55 mol% of repeating units (A11 ¹ ) and 45 repeating units (B1 ² ) with respect to all repeating units. It was confirmed that the polymer contained mol%. Mn of the polymer (A-3) was 3900, and Mw was 8100.

  The glass transition temperature of the polymer (A-3) measured using differential scanning calorimetry was 82 ° C. The polymer (A-3) was soluble in acetone, THF, ethyl acetate, R225 and xylene hexafluoride, respectively.

[Example 4] Production Example of Composition [Example 4-1] Production Example of Composition (1) A metaxylene hexafluoride solution (1.117 g) containing 0.36% by mass of polymer (A-1) and A uniform polymer solution was obtained by mixing with a solution (1.855 g) containing 5.4% by mass of the polymer (B-1). The polymer solution is filtered through a filter (made of PTFE) having a pore diameter of 0.2 μm, and contains 4.0% by mass of the polymer (A-1) with respect to the total amount of the polymer (B-1). A composition (1) was obtained.

[Example 4-2] Production Example of Composition (2) Metaxylene hexafluoride solution (1.117 g) containing 0.09% by mass of polymer (A-1) and 5.5% by mass of polymer A solution containing (B-1) (1.081 g) was mixed to obtain a uniform polymer solution. The polymer solution is filtered through a filter (made of PTFE) having a pore diameter of 0.2 μm, and contains 1.0% by mass of the polymer (A-1) with respect to the total amount of the polymer (B-1). A composition (2) was obtained.

[Example 4-3] Production Example of Composition (3) A 2-methyl-1-propanol solution (0.829 g) containing 0.96% by mass of the polymer (A-2) and 7.5% by mass of A solution (1.331 g) containing the polymer (B-1) was mixed to obtain a uniform polymer solution. The polymer solution is filtered through a filter (made of PTFE) having a pore diameter of 0.2 μm and contains 8.0% by mass of the polymer (A-2) with respect to the total amount of the polymer (B-1). A composition (3) was obtained.

[Example 4-4] Production Example of Composition (4) A 2-methyl-1-propanol solution (0.829 g) containing 0.96% by mass of the polymer (A-2) and 7.5% by mass of A solution (1.331 g) containing the polymer (B-2) was mixed to obtain a uniform polymer solution. The polymer solution is filtered through a filter (made of PTFE) having a pore diameter of 0.2 μm, and contains 8.0% by mass of the polymer (A-2) with respect to the total amount of the polymer (B-2). A composition (4) was obtained.

[Example 4-5] Production Example of Composition (5) 2-methyl-1-propanol solution (0.794 g) containing 0.50% by mass of polymer (A-3), and 7.8% by mass of A solution (1.285 g) containing the polymer (B-2) was mixed to obtain a uniform polymer solution. The polymer solution is filtered through a filter (made of PTFE) having a pore diameter of 0.2 μm, and contains 4.0% by mass of the polymer (A-3) with respect to the total amount of the polymer (B-2). A composition (5) was obtained.

[Example 4-6] Production Example of Composition (6) Polymer (Mw21000) (heavy) composed of the following repeating units (A1 ³ ) obtained by cyclopolymerizing CF ₂ = CFOCF ₂ CF ₂ CH═CH ₂ A meta-xylene hexafluoride solution containing 0.36% by mass of combined (A-3)) was prepared.

  The solution (1.117 g) and a solution (1.855 g) containing 5.4% by mass of the polymer (B-1) were mixed, and 3.8 based on the total amount of the polymer (B-1). A composition (6) containing mass% of the polymer (A-3) was obtained.

[Example 4-7] Production Example of Composition (7) Polymer (Mw93000) comprising the following repeating unit (A1 ⁴ ) obtained by cyclopolymerizing CF ₂ ═CFOCF ₂ CF (CF ₃ ) CH═CH ₂ ) (Referred to as polymer (A-4)) in the same manner as in Example 4-4, except that polymer (A-4) is used instead of polymer (A-4), to 3.8 relative to the total amount of polymer (B-1). A composition (7) containing mass% of the polymer (A-6) was obtained.

[Example 5] Evaluation of water repellency of composition Composition (1) was spin-coated on a silicon substrate on which an antireflection film (trade name AR26 manufactured by ROHM AHD HAAS Electronic Materials) was formed. Next, the silicon substrate was heat-treated to form a resin thin film (film thickness 50 nm) composed of the polymer (A-1) and the polymer (B-1) on the silicon substrate. Note that the heat treatment of the silicon substrate was performed by heating the silicon substrate at 100 ° C. for 90 seconds, and further heating at 130 ° C. for 60 seconds, or heating at 100 ° C. for 60 seconds.

Subsequently, the static contact angle, dynamic falling angle, and dynamic receding angle of the resin thin film with respect to water were measured. The results are shown in Table 1. In addition, the falling angle measured by the sliding method is called a dynamic falling angle, and the receding angle measured by the sliding method is called a dynamic receding angle.
A resin thin film is formed on a silicon substrate in the same manner except that each of the compositions (2) to (7) is used in place of the composition (1), and the static contact angle, dynamic falling angle and dynamic The receding angle was measured.
Moreover, the static contact angle, the dynamic falling angle, and the dynamic receding angle of the resin thin film consisting only of the polymer (B-1) were measured. The results are summarized in Table 1. The unit of the static contact angle, the dynamic falling angle, and the dynamic receding angle is an angle (°).

  As is clear from the above results, the resin thin film formed from the composition containing the polymer (A) and the polymer (B) is compared with the resin thin film formed only from the polymer (B), It turns out that it is excellent in water repellency and is especially excellent in dynamic water repellency. Therefore, when the immersion resist protective film composition of the present invention containing the polymer (A) and the polymer (B) is used in the immersion lithography method, the projection lens that moves at high speed on the immersion resist protective film is used. Since water follows well, stable and high-speed implementation of the immersion lithography method is possible.

[Example 6] Example of evaluation of development rate of composition Composition (1) was spin-coated on a crystal resonator, heat-treated and polymer (A-1) and polymer (B-1) on the crystal resonator A thin film is formed. Next, when the crystal resonator is immersed in an aqueous solution of tetramethylammonium hydroxide and the film reduction rate of the thin film in the aqueous solution is measured using the crystal resonator microbalance (QCM) method, the film reduction rate is 100 nm / s. That's it.

  As is apparent from the above results, the immersion resist protective film composition of the present invention can be easily removed with an alkaline aqueous solution. By using the immersion resist protective film composition of the present invention, an efficient immersion lithography method capable of removing the resist protective film and the photosensitive portion of the photosensitive resist with an alkaline solution after the immersion exposure step is realized.

According to the present invention, it is excellent in immersion resist protective film properties (inhibition of swelling of the photosensitive resist due to intrusion of water, suppression of elution of the photosensitive resist component into the liquid medium, etc.), high water repellency and infiltration into water. It is difficult to provide a resist protective film composition for immersion exposure that is particularly excellent in dynamic water repellency. By using the resist protective film composition for immersion exposure according to the present invention, a stable immersion lithography method capable of forming a high-resolution mask pattern image can be realized.

Claims (8)

A resist protective film composition for immersion exposure comprising the following polymer (A) and the following polymer (B), and 0.1 to 30% by mass of the polymer (A) with respect to the polymer (B).
Polymer (A): a repeating unit (A) formed by polymerization of a compound represented by the following formula (a1), a compound represented by the following formula (a2) or a compound represented by the following formula (a3) A polymer containing 10% by mole or more of the repeating unit (A) based on all repeating units.
_{^{CF 2 = CF-Q-CX}} 1 = CX 2 X 3 (a1).

However, the symbol in a formula shows the following meaning.
Q: 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. The hydrogen atom in the group is a group selected from the group consisting of an alkyl group, a fluoroalkyl group, an alkoxy group and a fluoroalkoxy group, and may be substituted with a group having 1 to 12 carbon atoms or a fluorine atom.
X ¹ : a hydrogen atom, a fluorine atom, an alkyl group having 1 to 12 carbon atoms, or a fluoroalkyl group having 1 to 12 carbon atoms.
X ² and X ³ : each independently a hydrogen atom or a fluorine atom.
W ¹ : A fluorine atom or a C 1-3 perfluoroalkoxy group.
W ² , W ³ , W ⁴ , W ⁵ : each independently a fluorine atom or a C 1-6 perfluoroalkyl group.
Polymer (B): formed by polymerization of a polymerizable monomer (b) having a polar group selected from the group consisting of hydroxy group, carboxy group, sulfonic acid group, sulfonylamide group, amino group and phosphoric acid group An alkali-soluble polymer containing repeating units. The polymer (A) is a polymer containing a repeating unit (A11) formed by polymerization of a compound represented by the following formula (a11), and 10 mol of the repeating unit (A11) with respect to all repeating units. The resist protective film composition for immersion exposure according to claim 1, wherein the resist protective film composition is a polymer containing at least%.
_{CF 2 = CF-CH 2 CHR} (CH 2) m -CX 11 = CH 2 (a11).
However, the symbol in a formula shows the following meaning.
R: an alkyl group having 1 to 12 carbon atoms or a fluoroalkyl group having 1 to 12 carbon atoms.
m: 0, 1 or 2.
X < ¹¹ >: A hydrogen atom or a C1-C12 alkyl group. The polymer (A) is a repeating unit (A11) formed by polymerization of a compound represented by the following formula (a11) and a repeating unit (B1) formed by polymerization of a compound represented by the following formula (b1) The polymer according to claim 1, wherein the polymer contains 10 mol% or more of the repeating unit (A11) and 10 mol% or more of the repeating unit (B1) with respect to all repeating units. The resist protective film composition for immersion exposure as described.
_{CF 2 = CF-CH 2 CHR} (CH 2) m -CX 11 = CH 2 (a11).
_{^{CF 2 = CF-Q b1 -CX}} b1 = CH 2 (b1).
However, the symbol in a formula shows the following meaning.
Q ^b1 : a group represented by the formula —CF ₂ C (CF ₃ ) (OH) (CH ₂ ) _n —, a formula —CH ₂ CH ((CH ₂ ) _p C (CF ₃ ) ₂ (OH)) (CH _{2) n} -, a group represented by or formula _{-CH 2 CH (C (O)} OH)) (CH 2) n - group represented by the.
n, p: each independently 0, 1 or 2.
X ^b1 : a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.   The resist protective film composition for immersion exposure according to any one of claims 1 to 3, wherein the polymerizable monomer (b) is a polymerizable monomer having a hydroxy group or a carboxy group.   The polymerizable monomer (b) is a polymerizable monomer having a hydroxy group or a carboxy group bonded to a carbon atom adjacent to a carbon atom to which a polyfluoroalkyl group is bonded. A resist protective film composition for immersion exposure according to 1. The polymerizable monomer (b) is represented by the following formula (b1), the following formula (b2), the following formula (b3) or the following formula (b4). The resist protective film composition for immersion exposure according to claim 1, wherein
_{^{CF 2 = CF-Q b1 -CX}} b1 = CH 2 (b1).
CH ₂ = CR ^b2 C (O) O—W ^b2 (—C (CF ₃ ) ₂ OH) _r (b2),
_{^{CH 2 = CH-W b3 (}} -C (CF 3) 2 OH) r (b3).

However, the symbol in a formula shows the following meaning.
Q ^b1 : a group represented by the formula —CF ₂ C (CF ₃ ) (OH) (CH ₂ ) _n —, a formula —CH ₂ CH ((CH ₂ ) _p C (CF ₃ ) ₂ (OH)) (CH _{2) n} -, a group represented by or formula _{-CH 2 CH (COOH) (CH} 2) n - group represented by the group represented by.
n, p: each independently 0, 1 or 2.
X ^b1 : a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.
R ^b2 : 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 ^b2 and W ^b3 : each independently a (r + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, which may contain a fluorine atom.
r: 1 or 2.
W ^b4 : a ^C 1-10 divalent hydrocarbon group that may contain a single bond or a fluorine atom.   The resist protective film composition for immersion exposure according to any one of claims 1 to 6, comprising an organic solvent. A step of applying a photosensitive resist on a substrate to form a resist film on the substrate, and applying the resist protective film composition for immersion exposure according to claim 7 on the resist film. A resist pattern forming method for forming a resist pattern on a substrate by sequentially performing a step of forming a resist protective film, an immersion exposure step, and a development step.