JPWO2009011364A1 - Resist composition used for lithography using electron beam, X-ray or EUV light - Google Patents

Abstract

Provided is a resist composition used in a lithography method using electron beam, X-ray or EUV light. A fluorine-containing polymer (PF) having a fluorine atom or a fluorine-containing alkyl group bonded to the main chain and having an alkali solubility increased by the action of an acid containing a repeating unit (F) having an aromatic ring structure in the side chain; And a resist composition used for lithography using electron beam, X-ray or EUV light. For example, the repeating unit (F) is at least one repeating unit (FVn) selected from the group consisting of the following repeating units (FV1), (FV2), (FV3) and (FV4) (XF1 is —F Or —CF 3, r 1 and r 2 are each independently an integer of 0 to 2 (the sum of r 1 and r 2 is an integer of 1 to 3), YF is an alkyl group, an alkoxyalkyl group, an alkylcarbonyl group and an alkoxycarbonyl group A group having 1 to 20 carbon atoms which may have a fluorine atom selected from the group consisting of an alkyl group, WF has a fluorine atom selected from the group consisting of an alkyl group, an alkoxyalkyl group and an alkoxycarbonylalkyl group; A group having 1 to 20 carbon atoms which may be present).

Description

  The present invention relates to a resist composition used in a lithography method using electron beam, X-ray or EUV light.

In the manufacture of an integrated circuit such as a semiconductor, a lithography method in which a mask pattern obtained by irradiating a mask with exposure light source light is projected onto a photosensitive resist film on a substrate and the pattern is transferred to the photosensitive resist film Is used. As the exposure light source is shorter wavelength light, the transferred pattern can be made finer. Therefore, ArF excimer laser light (wavelength 193 nm) and F ₂ excimer laser light (wavelength 157 nm) have been studied as exposure light sources. . Also, photosensitive resist materials corresponding to these exposure light sources have been actively developed.

On the other hand, in recent years, as a next-generation lithography method, a lithography method using an electron beam, X-ray or EUV light as an exposure light source has attracted attention.
As the photosensitive resist material in the lithography method, a resist composition containing a polymer whose alkali solubility is increased by the action of an acid and a photoacid generator is used.
As the polymer, Patent Document 1 describes a polymer containing a repeating unit of styrenes having no fluorine atom (the following repeating unit (P ^V1 ) and the like), and Patent Document 2 includes a fluorine-containing side chain. A polymer containing a repeating unit of an acrylate having an aliphatic ring structure (the following repeating unit ( ^FANb ) etc.) is described, and Patent Document 3 ^discloses a repeating aliphatic acrylate having a trifluoromethyl group bonded to the main chain. A polymer containing a unit (the following repeating unit (F ^AAd ) and the like) is described.

  Further, in Non-Patent Documents 1 and 2, a resist composition containing a polymer containing a repeating unit of styrenes having a chlorine atom or a bromine atom is compared with a resist composition containing a polymer not containing the repeating unit. Therefore, it is reported that the sensitivity to electron beams is high. However, Non-Patent Documents 1 and 2 do not describe a fluorine-containing polymer containing a repeating unit of styrenes having a fluorine atom.

JP 2005-266801 A JP 2005-275283 A JP 2005-275041 A Jpn. J. et al. Appl. Phys. 43 (6B), 2004, pp. 3971-3973 Jpn. J. et al. Appl. Phys. 44 (26), 2005, pp. L842-L844

The photosensitive resist material used in the lithography method using an electron beam, X-ray or EUV light as an exposure light source is highly sensitive to an electron beam, X-ray or EUV light. Desirable from. For this purpose, use is made of a polymer that promotes acid generation of an acid generator that is easily ionized or easily generates secondary electrons by electron beam, X-ray or EUV light, and that increases alkali solubility by the action of an acid. Is desirable.
Moreover, it is desirable that the resist film formed from the photosensitive resist material on the substrate is excellent in etching resistance from the viewpoint of forming an ultrafine pattern on the substrate.
However, there is no known polymer that satisfies these characteristics and has increased alkali solubility by the action of an acid.

The gist of the present invention is as follows.
<1> A fluorinated polymer having a fluorine atom or a fluorinated alkyl group bonded to the main chain and containing a repeating unit (F) having an aromatic ring structure in the side chain and having increased alkali solubility by the action of an acid A resist composition used for a lithography method using electron beam, X-ray or EUV light, comprising (PF) and a compound capable of generating an acid.

<2> The resist composition according to <1>, wherein the repeating unit (F) is a repeating unit represented by the following formula (F ^V ).

The symbols in the formula have the following meanings.
X ^F : a fluorine atom or a fluorine-containing alkyl group having 1 to 3 carbon atoms.
R ^F1 , R ^F2 , R ^F3 : each independently a hydrogen atom, a chlorine atom, a bromine atom, a fluorine atom, or a monovalent organic group having an aromatic ring structure having 6 to 20 carbon atoms, and R ^F1 , R ^F2 And at least one of R ^F3 is a monovalent organic group having an aromatic ring structure having 6 to 20 carbon atoms.

<3> A group in which the repeating unit (F) is composed of repeating units represented by the following formula (F ^V 1), the following formula (F ^V 2), the following formula (F ^V 3), and the following formula (F ^V 4). The resist composition according to <1> or <2>, which is at least one type of repeating unit (F ^V n) selected from:

The symbols in the formula have the following meanings.
X ^F1 : a fluorine atom or a trifluoromethyl group.
r1 and r2 are each independently an integer of 0 to 2, and the sum of r1 and r2 is an integer of 1 to 3.
Y ^F : an alkyl group, an alkoxyalkyl group, an alkylcarbonyl group represented by the formula —C (O) R, and a formula — (CH ₂ ) _n C (O) OR (n is an integer of 1 to 3) Carbon having 1 to 20 carbon atoms which may have a fluorine atom, or one or more groups represented by the formula —C (CF ₃ ) ₂ OH, selected from the group consisting of alkoxycarbonylalkyl groups A monovalent organic group of formula 4-20.
W ^F : has a fluorine atom selected from the group consisting of an alkyl group, an alkoxyalkyl group, and an alkoxycarbonylalkyl group represented by the formula — (CH ₂ ) _n C (O) OR (n is an integer of 1 to 3). Or a monovalent organic group having 4 to 20 carbon atoms, which may have one or more groups represented by the formula -C (CF ₃ ) ₂ OH.

<4> The resist composition according to any one of <1> to <3>, wherein the ratio of the weight average molecular weight to the number average molecular weight of the fluoropolymer (PF) is 1.5 or less.
<5> The resist composition according to any one of <1> to <4>, wherein the compound that generates acid is a compound that generates sulfonic acid upon irradiation with actinic rays.
<6> The resist composition according to any one of <1> to <5>, including 0.1 to 20 parts by mass of an acid-generating compound with respect to 100 parts by mass of the total mass of the fluoropolymer (PF). .
<7> The resist composition according to any one of <1> to <6>, wherein the fluoropolymer (PF) contains 1 to 80 mol% of the repeating unit (F) with respect to all repeating units.
<8> The resist composition according to any one of <1> to <7>, wherein the fluoropolymer (PF) is produced by living radical polymerization or living cationic polymerization of a monomer that forms the repeating unit (F). object.

<9> The fluoropolymer (PF) is composed of repeating units represented by the following formula (G ^V 1), the following formula (G ^V 2), the following formula (G ^V 3), and the following formula (G ^V 4). The resist composition according to any one of <1> to <8>, comprising at least one repeating unit (G ^V n) selected from the group.

The symbols in the formula have the following meanings.
R ^G1 , R ^G2 and R ^G3 : each independently a hydrogen atom, an alkyl group or a hydroxyalkyl group.
T ^G : a hydrogen atom, a halogen atom, a methyl group, a hydroxyalkyl group or a haloalkyl group.
Z ^G and W ^G : each independently an acid-decomposable group having 1 to 20 carbon atoms.
g: An integer of 1 to 4.

<10> The fluorine-containing polymer (PF) is represented by the following formula (Q ^V 1), the following formula (Q ^V 2), the following formula (Q ^V 3), the following formula (Q ^V 4), and the following formula (Q ^V 5). The resist composition according to any one of <1> to <9>, comprising at least one repeating unit (Q ^V n) selected from the group consisting of repeating units represented by:

The symbols in the formula have the following meanings.
R ^Q1 , R ^Q2 and R ^Q3 : each independently a hydrogen atom, an alkyl group or a hydroxyalkyl group.
T ^Q : a hydrogen atom, a halogen atom, a methyl group, a hydroxyalkyl group or a haloalkyl group.
q: An integer of 1 to 4.

<11> The fluoropolymer (PF) includes a repeating unit (F ^V n), a repeating unit (G ^V n), and a repeating unit (Q ^V n), and the repeating unit (F the ^V n) contains 5 to 50 mol%, wherein the repeating units ^(G V n) ^10~80 mol%, including repeating units ^(Q V n) from 5 to 50 mol%, the resist composition according to <10> .
<12> A resist forming composition for use in a lithography method using an electron beam, X-rays or EUV light, comprising the resist composition according to any one of <1> to <11> and an organic solvent.

  According to the present invention, there is provided a resist composition having high sensitivity to electron beam, X-ray or EUV light, excellent etching resistance, and used for lithography using electron beam, X-ray or EUV light.

In the present specification, symbols in groups are as defined above unless otherwise specified.
In this specification, the compound represented by the formula (f) is the compound (f), the repeating unit represented by the formula (F) is the repeating unit (F), the group represented by the formula -OY ^F is- Also referred to as OY ^F. Other compounds and other groups are also described in the same manner.

  The present invention relates to a fluorine-containing polymer having an alkali solubility increased by the action of an acid having a repeating unit (F) having a fluorine atom or a fluorine-containing alkyl group bonded to the main chain and having an aromatic ring structure in the side chain. Provided is a resist composition used in a lithography method (hereinafter also simply referred to as a lithography method) using electron beam, X-ray or EUV light, which comprises (PF) and a compound that generates an acid (acid generator). To do.

Since the fluoropolymer (PF) in the present invention has a fluorine atom having a large absorption cross section for electron beam, X-ray or EUV light and has an aromatic ring structure, it is ionized by electron beam, X-ray or EUV light. Or secondary electrons are likely to be emitted. Therefore, it is considered that the fluoropolymer (PF) is easily activated by electron beam, X-ray or EUV light and promotes acid generation of the acid generator. Therefore, it is considered that the resist composition of the present invention has high acid generation efficiency and high sensitivity to electron beams, X-rays or EUV light.
In addition, the fluorinated polymer (PF) is a polymer having a fluorine atom or a fluorinated alkyl group bonded to the main chain, and the main chain is ionized by electron beam, X-ray or EUV light or emitted by secondary electrons. It is considered that the alkali solubility is likely to increase because the molecular weight is reduced by being divided. The increase in alkali solubility means that the protective group of the alkali-soluble group in the polymer is deprotected by the action of an acid, for example, and the polymer becomes soluble in an alkaline aqueous solution. In general, for lithography applications, a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution is used as a developer as an alkaline aqueous solution. The development rate (nm / s) is used as an indicator of alkali solubility. Generally, if it is 10 nm / s or more, it can be used as an alkali-soluble polymer.
Therefore, the exposed portion of the photosensitive resist film formed from the resist composition of the present invention can be easily removed with an alkali developer.
Therefore, by using the resist composition of the present invention, it is possible to form a very fine pattern by lithography.

  The repeating unit (F) in the fluoropolymer (PF) may consist of only one type or may consist of two or more types.

The repeating unit (F) is not particularly limited as long as it has a fluorine atom or a fluorine-containing alkyl group bonded to the main chain and has an aromatic ring structure in the side chain. The aromatic ring structure in the fluoropolymer (PF) is preferably directly bonded to the main chain.
The repeating unit (F) is preferably the following repeating unit (F ^V ).
The fluorinated polymer (PF) preferably contains a repeating unit (F ^V ) as an essential component. In addition to the repeating unit (F ^V ), it is more preferable that the repeating unit (G ^V n) and / or the repeating unit (Q ^V n) be included as an optional component.

X ^F is preferably a fluorine atom or a trifluoromethyl group.

R ^F1 , R ^F2 and R ^F3 are each independently preferably a hydrogen atom, a fluorine atom or a monovalent organic group having an aromatic ring structure having 6 to 20 carbon atoms, and R ^F1 and R ^F2 are each a hydrogen atom or It is particularly preferable that it is a monovalent organic group which is a fluorine atom and R ^F3 has an aromatic ring structure having 6 to 20 carbon atoms.
In addition, a functional group (hydroxy group, carboxyl group, etc.) or a group derived from the functional group may be bonded to the carbon atom forming the aromatic ring structure in the monovalent organic group.

The repeating unit (F) is at least one selected from the group consisting of the following repeating unit (F ^V 1), the following repeating unit (F ^V 2), the following repeating unit (F ^V 3), and the following repeating unit (F ^V 4). Particular preference is given to seed repeating units (F ^V n). The repeating unit (F) is particularly preferably the following repeating unit (F ^V 1).

The position of the carbon atom of the benzene ring to which —OH or —OY ^F is bonded in the repeating unit (F ^V 2) and the position of the carbon atom of the benzene ring to which —COOH or —COOY ^F is bonded in the repeating unit (F ^V 3) And the position of the carbon atom of the benzene ring to which —C (CF ₃ ) ₂ OH or —C (CF ₃ ) ₂ OY ^F is bonded in the repeating unit (F ^V 4) is not particularly limited.

It is preferable that one of r1 and r2 is 1 and the other is 0, or each is 1.
Y ^F is a methyl group, described in group (g1), below the group (g2), preferably a later group (g3) or later group (g4).
W ^F is methyl, below the group (g1), is preferably below the group (g2) or later group (g3).

  Specific examples of the repeating unit (F) include the following repeating units. Among them, the repeating unit (F) is preferably a repeating unit based on polymerization of 2-fluorostyrene or 2-trifluoromethylstyrene.

  The fluoropolymer (PF) preferably contains 1 mol% or more of the repeating unit (F) with respect to all repeating units. Moreover, the upper limit of a repeating unit (F) is not specifically limited, 80 mol% or less is preferable. It is more preferable that the repeating unit (F) is contained in an amount of 5 to 50 mol%.

The fluoropolymer (PF) is a fluoropolymer whose alkali solubility is increased by the action of an acid.
The fluorinated polymer (PF) preferably contains a repeating unit having a group (acid-decomposable group) that is decomposed by the action of an acid. The following repeating unit (G ^V 1), the following repeating unit (G ^V 2), It is particularly preferable to include at least one repeating unit (G ^V n) selected from the group consisting of the following repeating unit (G ^V 3) and the following repeating unit (G ^V 4).

R ^G1 , R ^G2 and R ^G3 in the repeating units (G ^V 1), (G ^V 2) and (G ^V 4) are each preferably a hydrogen atom.
T ^G in the repeating unit (G V ³⁾ is a hydrogen atom, a fluorine atom, preferably a methyl group or a trifluoromethyl group.
Z ^G in the repeating unit (G ^V 1) and the repeating unit (G ^V 4) is each independently a group represented by the formula —C (Z ^A ) (Z ^B ) O (Z ^C ); group (g1) A group represented by formula -C (O) C (Z ^D ) ₃ ; a group represented by group (g2), formula -C (Z ^D ) ₃ ; a group (g3) or a formula -C (Z ^A ) A group represented by (Z ^B ) C (O) OC (Z ^D ); preferably a group (g4).
W ^G in the repeating unit (G ^V 2) and the repeating unit (G ^V 3) is each independently a group represented by the formula —C (Z ^A ) (Z ^B ) O (Z ^C ); group (g1) And a group represented by the formula -C (O) C (Z ^D ) ₃ ; a group represented by the group (g2) or the formula -C (Z ^D ) ₃ ; and a group (g3).
The symbols in the formula have the following meanings (the same applies hereinafter).
Z ^A and Z ^B are each independently a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms.
Z ^C : a hydrocarbon group having 1 to 16 carbon atoms.
Z ^D : a hydrocarbon group having 1 to 16 carbon atoms, and three Z ^D may be the same or different. Further, two Z ^D may form a cyclic hydrocarbon group in cooperation with the carbon atom in the formula.

  Specific examples of the group (g1) include the following groups.

  Specific examples of the group (g2) include the following groups.

  Specific examples of the group (g3) include the following groups.

基（ｇ４）の具体例としては、下記の基が挙げられる。

Specific examples of the group (g4) include the following groups.

G in the repeating units (G ^V 1), (G ^V 2) and (G ^V 4) is preferably 1.
As the repeating unit (G ^V n), it is particularly preferable that the repeating unit is (G ^V 2), R ^G1 , R ^G2 and R ^G3 are each a hydrogen atom and g is 1.

  The fluoropolymer (PF) preferably contains 1 mol% or more of repeating units having an acid-decomposable group with respect to all repeating units. The upper limit of the repeating unit is not particularly limited and is preferably 80 mol% or less.

The fluoropolymer (PF) further includes the following repeating unit (Q ^V 1), the following repeating unit (Q ^V 2), the following repeating unit (Q ^V 3), the following repeating unit (Q ^V 4) and the following repeating unit. It is preferable to include at least one repeating unit (Q ^V n) selected from the group consisting of (Q ^V 5).

R ^Q1 , R ^Q2 and R ^Q3 in the repeating units (Q ^V 1) to (Q ^V 3) and (Q ^V 5) are each preferably a hydrogen atom.
T ^Q in the repeating unit (Q ^V 3) is preferably a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.
Q in the repeating units (Q ^V 1), (Q ^V 2) and (Q ^V 5) is preferably 1.

Specific examples of the repeating unit (Q ^V n) include the following compounds. As the repeating unit (Q ^V n), a repeating unit based on the polymerization of hydroxystyrene is particularly preferable.

The fluoropolymer (PF) preferably contains 1 mol% or more of repeating units (Q ^V n) based on all repeating units. The upper limit of the repeating units ^(Q V n) is not particularly limited, but is preferably 80 mol% or less.

  The weight average molecular weight of the fluoropolymer (PF) is preferably 1000 to 100,000.

The fluorinated polymer (PF) is preferably a polymer having a narrow molecular weight distribution. The ratio of the weight average molecular weight to the number average molecular weight of the fluoropolymer (PF) (weight average molecular weight / number average molecular weight) is preferably 1.5 or less, particularly preferably 1.4 or less. The lower limit of the ratio is not particularly limited and is 1.0.
The fluorine-containing polymer (PF) in this case has a particularly high transparency and sensitivity to electron beams, X-rays or EUV light, etching resistance, and solubility in an alkali developer, and has high resolution and a good pattern shape. The composition can be more easily prepared.

The fluorine-containing polymer (PF) having a narrow molecular weight distribution is preferably produced by living polymerization of a monomer that forms the repeating unit (F), more preferably produced by living radical polymerization or living cationic polymerization. It is particularly preferred to produce by cationic polymerization.
Living radical polymerization in this specification means not only radical polymerization in which polymerization end activity is always maintained in the polymerization of monomers, but also the species in which the polymerization end is deactivated and the polymerization end are activated. It also means quasi-living polymerization that proceeds in equilibrium with the generated species.

Living radical polymerization is a method using a chain transfer agent such as a thiocarbonylthio compound (for example, a method described in WO 1998/001478 pamphlet), a method using a radical scavenger such as a cobalt porphyrin complex or a nitroxide compound, or It is preferably carried out by an atom transfer radical polymerization method using an organic halide or the like as an initiator and a transition metal complex as a catalyst.
The living cationic polymerization in this specification means not only cationic polymerization in which the activity of the polymerization terminal is always maintained in the polymerization of the monomer, but also the species whose polymerization terminal is deactivated and the polymerization terminal are activated. It also means quasi-living polymerization that proceeds in equilibrium with the generated species.

  Living cationic polymerization is performed by polymerizing a monomer that forms the repeating unit (F) in the presence of an organic halogen compound, a Lewis acidic metal halide compound, and a solvent as one component of a polymerization initiator. preferable.

Specific examples of the organic halogen compound include halobenzene, 1-phenylalkyl halide, 2-phenylalkyl halide, and diphenylalkyl halide.
Specific examples of Lewis acidic metal halide compounds include SnCl ₄ , SnBr ₄ , BF ₃ , AlCl ₃ , AlBr ₃ , SbCl ₅ , FeCl ₃ , TiCl ₄ , and Al (CH ₂ CH ₃ ) ₂ Cl.
Specific examples of the solvent include methylene chloride, chloroform, benzene, toluene, nitromethane, and nitrobenzene.
The reaction temperature in the living radical polymerization is preferably -78 ° C to 0 ° C. The reaction pressure is not particularly limited.

As a preferable aspect of the fluoropolymer (PF) in the present invention, it contains a repeating unit (F ^V n) and a repeating unit (G ^V n), and the repeating unit (F ^V n) is contained in all repeating units. Examples thereof include a fluorine-containing polymer containing 5 to 50 mol% and containing 10 to 80 mol% of repeating units (G ^V n). The fluoropolymer further preferably contains 5 to 50 mol% of repeating units (Q ^V n) based on all repeating units.
As for the weight average molecular weight of the fluoropolymer in the said aspect, 1000-30000 are preferable. The ratio of the weight average molecular weight to the number average molecular weight of the fluoropolymer in the above embodiment is preferably 1.0 to 1.5, and particularly preferably 1.0 to 1.4.

  The acid generator in the present invention is a compound that generates an acid by the action of an electron beam, X-ray or EUV light (hereinafter also referred to as a photoacid generator), and is usually an electron beam, X-ray or EUV light. (Hereinafter, these are also referred to as actinic rays) are compounds that generate an acid when a chemical bond is cleaved by irradiation. The compound may be a non-polymer compound or a polymer compound.

  The photoacid generator is not particularly limited, and examples thereof include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates. The photoacid generator is preferably a compound that generates sulfonic acid when irradiated with actinic rays. Examples of the compound include sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, and disulfones.

  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 nonaflate, triphenylsulfonium perfluorooctanesulfonate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, triphenylsulfonium trifluoromethanesulfone Narate, triphenylsulfonium N-sulfolonium, 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 trifluoro Lomethanesulfonate, bis (t-butylphenyl) iodonium tri Fluoromethanesulfonate, 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, and the like.

  The resist composition of the present invention preferably contains 0.1 to 20 parts by mass of an acid generator, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the total mass of the fluoropolymer (PF). Is particularly preferred.

The resist composition of the present invention is preferably prepared as a liquid composition because it is usually used after being applied to an electron beam, X-ray or EUV lithography method after being coated on a substrate surface and dried to form a film. .
The present invention provides a resist forming composition comprising the resist composition of the present invention and an organic solvent. It is preferable that the resist forming composition of this invention contains 100-10000 mass parts of organic solvents with respect to 100 mass parts of total mass of a fluoropolymer (PF).

An organic solvent will not be specifically limited if it is a solvent with high compatibility with a fluorine-containing polymer (PF) and an acid generator. The organic solvent may be a fluorinated organic solvent or a non-fluorinated organic solvent that does not contain a fluorine atom.
Specific examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and diacetone alcohol; ketones such as acetone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-heptanone, 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, ethyl 3-ethoxypropionate, methyl β-methoxyisobutyrate, ethyl butyrate, butyric acid Esters such as propyl, methyl isobutyl ketone, ethyl acetate, 2-ethoxyethyl acetate, isoamyl acetate, methyl lactate, ethyl lactate; toluene, xylene Aromatic hydrocarbons such as 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, and the like; N, N -Amides such as dimethylformamide and N, N-dimethylacetamide.

The method for forming a resist pattern by the electron beam, X-ray or EUV lithography method using the resist forming composition of the present invention is not particularly limited.
As a method of forming the resist pattern, a step of forming a resist film formed from the resist composition of the present invention on the substrate by removing the organic solvent after applying the resist forming composition of the present invention on the substrate, The resist pattern on which a resist pattern is formed is obtained by performing an electron beam, X-ray or EUV light exposure process on the resist film on the substrate, and a developing process for removing the photosensitive portion of the resist film in this order. A forming method is mentioned. In the said formation method, you may combine a heating process, a rinse process, and a drying process further suitably. Note that exposure is a concept that includes irradiation with an electron beam, X-rays, or EUV light.

The substrate is not particularly limited, and examples thereof include a silicon substrate whose surface is coated with silicon dioxide, a glass substrate, an ITO substrate, and a quartz substrate whose surface is coated with chromium oxide.
The development process is performed until the alkali solution is brought into contact with the resist film side until the exposed portion of the resist film is removed.

  Specific examples of the alkaline solution include an alkaline aqueous solution containing an alkaline compound selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide and triethylamine.

The present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
In Examples, the weight average molecular weight is Mw, the number average molecular weight is Mn, and the ratio of Mw to Mn is Mw / Mn. Azobisisobutyronitrile is referred to as AIBN, propylene glycol methyl ether acetate as PGMEA, tetrahydrofuran as THF, and polystyrene as PSt.
As the acid generator, triphenylsulfonium nonaflate ((Ph) ₃ S ⁺ C ₄ F ₉ —SO ₃ ⁻ ), which is a photoacid generator, was used.
In order to produce a polymer, one of the following compounds was used.

The following repeating unit (F ^V 11) is simply the unit (F ^V 11), the following repeating unit (G ^V 21) is simply the unit (G ^V 21), and the following repeating unit (Q ^V 11) is the unit (Q ^V 11).

  The following compound (x1) was used as a reversible addition-cleavage chain transfer agent used for living radical polymerization.

Mw and Mn of the polymer were measured using a gel permeation chromatography method (developing solvent: THF, internal standard: PSt).
Specifically, a SEC column (trade name: TSKgel SuperHZ-2000, 3000, and 4000, manufactured by Tosoh Corporation) is used as an analytical column, and Mw / Mn is 1.15 or less as an internal standard for molecular weight measurement. 12 different types of PSt (Mw 495 to Mw 111000) were used. The flow rate of the mobile phase (developing solvent: THF) was 0.35 ml / min, and the column temperature was 40 ° C.

[Example 1] Production Example of Fluoropolymer (PF) [Example 1-1] Production Example of Polymer (1) To a round bottom flask with a three-way cock (internal volume 25 mL, glass), compound (f ^V 11 ) (0.5 g), compound (g ^V 21) (1.0 g), compound (pq ^V 11) (1.7 g) and methylene chloride (2.5 g) were charged. Next, a methylene chloride solution containing 1.0 mol / L of 1-phenylethyl chloride (1.0 ml), a methylene chloride solution containing 1.0 mol / L of bromobenzene (1.2 ml) and tetra-n-butylammonium chloride ( 4.0 ml) was added, and the flask was kept at -15 ° C. Further, a methylene chloride solution (5.0 ml) containing 1.0 mol / L of tin tetrachloride was added to start living cationic polymerization, and polymerization was carried out for 8 hours as it was.

  Next, the solid content obtained by dropping the solution in the flask into methanol was recovered and vacuum-dried at 80 ° C. for 24 hours to obtain a powdery amorphous polymer (p1) (1.4 g). Got. A reactor (made of glass) was charged with the polymer (p1) (1.3 g) and THF (10 ml), and then charged with a THF solution (20 ml) containing 1.0 mol / L of tetrabutylammonium fluoride. Reaction was performed at 25 degreeC for 4 hours. Next, the solid content obtained by dropping the solution in the reactor into water was recovered and vacuum-dried at 80 ° C. for 24 hours to obtain a brown powdery amorphous polymer (1) (0.8 g). ) The polymer (1) was soluble in toluene, acetone, THF, and PGMEA, respectively.

Mn of the polymer (1) was 9800, Mw was 11000, and Mw / Mn was 1.12.
As a result of analyzing the polymer (1) using ¹⁹ F-NMR and ¹ H-NMR, the polymer (1) was found to contain 13 mol% of repeating units (F ^V 11), repeating units (F G ^V 21) was confirmed to be a polymer containing 36 mol% and the repeating unit (Q ^V 11) was 51 mol%.

[Example 1-2] Production example of polymer (2) In a pressure-resistant reaction vessel (internal volume 100 mL, glass), compound (f ^V 11) (0.5 g), compound (g ^V 21) (1.0 g) Compound (pq ^V 11) (1.7 g) and toluene (1.1 g) were charged, and then AIBN (0.01 g) and compound (x ¹ ) (0.003 g) were charged.

  After freezing and degassing the inside of the reactor, the reactor was sealed, and living radical polymerization was performed at a reactor internal temperature of 80 ° C. for 42 hours. Next, the solid content obtained by dropping the solution in the reactor into methanol was recovered and dried in vacuo at 80 ° C. for 24 hours to obtain a pink powdery amorphous polymer (p2) (2. 0 g) was obtained. A reactor (made of glass) was charged with the polymer (p2) (2.0 g) and THF (10 mL), and then a THF solution (20 mL) containing 1.0 mol / L of tetrabutylammonium fluoride was charged into the reactor. The reaction was performed at an internal temperature of 25 ° C. for 4 hours.

  Next, the solid content obtained by dripping the solution in the reactor into water was collected and vacuum-dried at 80 ° C. for 24 hours to obtain a brown powdery amorphous polymer (2) (1.5 g). ) The polymer (2) was soluble in toluene, acetone, THF, and PGMEA, respectively.

Mn8500 of the polymer (2) was Mw of 11000, and Mw / Mn was 1.30.
As a result of analyzing the polymer (2) using ¹⁹ F-NMR and ¹ H-NMR, the polymer (2) was found to contain 10 mol% of units (F ^V 11) and units (G ^{V V} ) with respect to all repeating units. 21) was confirmed to be a polymer containing 40 mol% and the unit (Q ^V 11) 50 mol%.

[Example 1-3] Production example of polymer (3) In a pressure-resistant reaction vessel (internal volume 100 mL, made of glass), compound (f ^V 11) (0.4 g), compound (g ^V 21) (1.0 g) was charged with compound ^(pq V 11) ^(1.8g) and toluene (3.3 g), then it was charged with AIBN (0.3 g).
After the inside of the reactor was frozen and degassed, the reactor was sealed and polymerization was carried out at a reactor internal temperature of 60 ° C. for 16 hours. Next, the solid content obtained by dripping the solution in the reactor into methanol was recovered and vacuum-dried at 80 ° C. for 24 hours to obtain a brown powdery amorphous polymer (p3) (2. 5 g) was obtained. Polymer (p3) (2.5 g) and THF (10 mL) were charged into a glass reactor, and then a THF solution (25 mL) containing 1.0 mol / L of tetrabutylammonium fluoride was charged. Reaction was performed at 25 degreeC for 4 hours. Next, the solid content obtained by dripping the solution in the reactor into water was collected and vacuum-dried at 80 ° C. for 24 hours to obtain a brown powdery amorphous polymer (3) (1.9 g). ) The polymer (3) was soluble in toluene, acetone, THF, and PGMEA, respectively.

Mn of the polymer (3) was 6600, Mw was 14000, and Mw / Mn was 2.1.
As a result of analyzing the polymer (3) using ¹⁹ F-NMR and ¹ H-NMR, the polymer (3) was found to contain 10 mol% of units (F ^V 11) and units (G ^{V V} ) with respect to all repeating units. 21) was confirmed to be a polymer containing 42 mol% and units (Q ^V 11) of 48 mol%.

[Example 2] Exposure evaluation example of EUV light A solution obtained by dissolving polymer (1) (1 g) and acid generator (0.1 g) in PGMEA (20 g) was filtered with a filter (PTFE having a pore size of 0.2 μm). The resist-forming composition (1) was obtained through filtration.
A resist formed from the resist-forming composition (1) by spin-coating the resist-forming composition (1) on a silicon substrate surface-treated with hexamethyldisilazane and heating the silicon substrate at 100 ° C. for 90 seconds. A silicon substrate having a film (film thickness 0.15 μm) was obtained.

Each of the EUV light having an exposure intensity of 0.1, 0.5, ¹ , ² , ^{3, 5} , 8, 10 mJ / cm ² is exposed to each specific portion of the resist film of the silicon substrate. EUVES-7000 manufactured by RISOTEC JAPAN is used for EUV light exposure.
Next, the silicon substrate is heated at 100 ° C. for 90 seconds, and further the resist film is developed using an alkaline solution to remove the resist film exposed to EUV light. Subsequently, when the remaining film thickness of the resist film is measured according to the exposure intensity of the exposed EUV light, the exposure intensity of the EUV light necessary for completely exposing the resist film and removing it by development is 1.0 mJ / cm. ² or less.

Resist-forming compositions (2) and (3) were obtained using the polymer (2) and the polymer (3) in the same manner as in the case of the polymer (1). Similarly, when an exposure test is performed, the exposure intensity of EUV light necessary for completely exposing the resist film and removing it by development is 1.0 mJ / cm ² or less.
From the above results, it can be seen that a resist film formed from a fluoropolymer containing a repeating unit having a fluorine atom in the main chain and an aromatic ring structure in the side chain has high sensitivity to EUV light.

[Example 3] Evaluation example of etching resistance The solution obtained by dissolving the polymer (1) (1 g) in PGMEA (15 g) was filtered through a filter (made of PTFE) having a pore diameter of 0.2 μm, A polymer solution was obtained. The polymer solution was spin-coated on a silicon substrate, and the silicon substrate was heated at 100 ° C. for 90 seconds to obtain a silicon substrate having a polymer (1) thin film (film thickness: 0.2 μm).
Subsequently, an etching test of the silicon substrate is performed, and the etching rate of the thin film of the polymer (1) is measured. The etching test was performed using RIE-10NR manufactured by Samco (etching conditions: pressure: 2 Pa, etching gas: mixed gas of CF ₄ (80% by volume) and O ₂ (20% by volume), output: 70 W, time : 60 seconds).

A similar etching test was performed using a thin film of poly-p-hydroxystyrene (Mw 8000) instead of the polymer (1), and the etching rate (unit: nm / min) of poly-p-hydroxystyrene was measured. .
The etching rate ratio of the polymer (1) to the etching rate of poly-p-hydroxystyrene was around 1.1.

Using the polymer (2) and the polymer (3), a polymer solution was obtained in the same manner as in the case of the polymer (1). Similarly, an etching test is conducted, and the etching rate ratio of the polymer (2) and the polymer (3) to the etching rate of poly-p-hydroxystyrene is around 1.1.
From the above results, it can be seen that a fluoropolymer having a fluorine atom in the main chain and an aromatic ring structure in the side chain has sufficient etching resistance.

ADVANTAGE OF THE INVENTION According to this invention, the resist composition used for the lithography method using an electron beam, X-rays, or EUV light has high sensitivity with respect to an electron beam, X-rays, or EUV light, and is excellent also in resolving power and etching resistance. The The resist composition of the present invention has high sensitivity and high resolution, good pattern shape, and line edge roughness (the edge between the pattern formed on the photosensitive resist material and the substrate interface fluctuates in the direction perpendicular to the line direction). In other words, the positive resist composition satisfies the above-mentioned phenomenon in which the edge viewed from directly above the pattern appears uneven. By using the resist composition of the present invention, a very fine pattern can be formed by the lithography method.

The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2007-187462 filed on July 18, 2007 are incorporated herein as the disclosure of the specification of the present invention. It is.

Claims (12)

  A fluorine-containing polymer (PF) having a fluorine atom or a fluorine-containing alkyl group bonded to the main chain and containing a repeating unit (F) having an aromatic ring structure in the side chain and having increased alkali solubility by the action of an acid And a compound that generates an acid, and a resist composition used in a lithography method using an electron beam, X-rays, or EUV light. The resist composition according to claim 1, wherein the repeating unit (F) is a repeating unit represented by the following formula (F ^V ).

The symbols in the formula have the following meanings.
X ^F : a fluorine atom or a fluorine-containing alkyl group having 1 to 3 carbon atoms.
R ^F1 , R ^F2 , R ^F3 : each independently a hydrogen atom, a chlorine atom, a bromine atom, a fluorine atom, or a monovalent organic group having an aromatic ring structure having 6 to 20 carbon atoms, R ^F1 , R ^F2 And at least one of R ^F3 is a monovalent organic group having an aromatic ring structure having 6 to 20 carbon atoms. The repeating unit (F) is selected from the group consisting of repeating units represented by the following formula (F ^V 1), the following formula (F ^V 2), the following formula (F ^V 3), and the following formula (F ^V 4). The resist composition according to claim 1, wherein the resist composition is at least one repeating unit (F ^V n).

The symbols in the formula have the following meanings.
X ^F1 : a fluorine atom or a trifluoromethyl group.
r1 and r2 are each independently an integer of 0 to 2, and the sum of r1 and r2 is an integer of 1 to 3.
Y ^F : an alkyl group, an alkoxyalkyl group, an alkylcarbonyl group represented by the formula —C (O) R, and a formula — (CH ₂ ) _n C (O) OR (n is an integer of 1 to 3) Carbon having 1 to 20 carbon atoms which may have a fluorine atom, or one or more groups represented by the formula —C (CF ₃ ) ₂ OH, selected from the group consisting of alkoxycarbonylalkyl groups A monovalent organic group of formula 4-20.
W ^F : has a fluorine atom selected from the group consisting of an alkyl group, an alkoxyalkyl group, and an alkoxycarbonylalkyl group represented by the formula — (CH ₂ ) _n C (O) OR (n is an integer of 1 to 3). Or a monovalent organic group having 4 to 20 carbon atoms, which may have one or more groups represented by the formula -C (CF ₃ ) ₂ OH.   The ratio of the weight average molecular weight with respect to the number average molecular weight of a fluoropolymer (PF) is 1.5 or less, The resist composition in any one of Claims 1-3.   The resist composition according to claim 1, wherein the acid-generating compound is a compound that generates sulfonic acid upon irradiation with actinic rays.   The resist composition in any one of Claims 1-5 containing 0.1-20 mass parts of compounds which generate | occur | produce an acid with respect to 100 mass parts of total mass of a fluoropolymer (PF).   The resist composition according to any one of claims 1 to 6, wherein the fluoropolymer (PF) contains 1 to 80 mol% of the repeating unit (F) with respect to all repeating units.   The resist composition according to any one of claims 1 to 7, wherein the fluoropolymer (PF) is produced by living radical polymerization or living cationic polymerization of a monomer that forms the repeating unit (F). The fluoropolymer (PF) is selected from the group consisting of repeating units represented by the following formula (G ^V 1), the following formula (G ^V 2), the following formula (G ^V 3), and the following formula (G ^V 4). The resist composition according to claim 1, comprising at least one selected repeating unit (G ^V n).

The symbols in the formula have the following meanings.
R ^G1 , R ^G2 and R ^G3 : each independently a hydrogen atom, an alkyl group or a hydroxyalkyl group.
T ^G : a hydrogen atom, a halogen atom, a methyl group, a hydroxyalkyl group or a haloalkyl group.
Z ^G and W ^G : each independently an acid-decomposable group having 1 to 20 carbon atoms.
g: An integer of 1 to 4. The fluoropolymer (PF) is represented by the following formula (Q ^V 1), the following formula (Q ^V 2), the following formula (Q ^V 3), the following formula (Q ^V 4), and the following formula (Q ^V 5). The resist composition according to claim 1, comprising at least one repeating unit (Q ^V n) selected from the group consisting of repeating units.

The symbols in the formula have the following meanings.
R ^Q1 , R ^Q2 and R ^Q3 : each independently a hydrogen atom, an alkyl group or a hydroxyalkyl group.
T ^Q : a hydrogen atom, a halogen atom, a methyl group, a hydroxyalkyl group or a haloalkyl group.
q: An integer of 1 to 4. The fluoropolymer (PF) includes a repeating unit (F ^V n), a repeating unit (G ^V n), and a repeating unit (Q ^V n), and the repeating unit (F ^V n) with respect to all repeating units. The resist composition according to claim 10, comprising 5 to 50 mol% of repeating units, 10 to 80 mol% of repeating units (G ^V n), and 5 to 50 mol% of repeating units (Q ^V n).   The resist formation composition used for the lithography method using an electron beam, a X-ray, or EUV light containing the resist composition in any one of Claims 1-11, and an organic solvent.