JP2009080482A - Positive resist composition and pattern-forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist composition, which not only in normal exposure (dry exposure) but also in immersion exposure, causes few development defects, has film shrinkage resistance, excels also in line edge roughness, suppresses generation of scum, and has proper conformability to an immersion liquid in immersion exposure, and to provide a pattern forming method that uses the same. <P>SOLUTION: The resist composition comprises (A) resin, of which the solubility in an alkali developer increases by the action of an acid, (B) a compound which generates an acid upon irradiation with actinic rays or radiation, (C) a resin containing neither fluorine atoms nor silicon atoms, and having a degree of molecular weight dispersion of 1.3 or smaller and a weight average molecular weight of ≤1.0×10<SP>4</SP>, and (D) a solvent. The pattern-forming method that uses the composition is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resist composition used in a semiconductor manufacturing process such as an IC, a circuit board such as a liquid crystal or a thermal head, and a lithography process for other photo applications, a resin used in the resist composition, and the resin. And a pattern forming method using the positive resist composition. In particular, a resist composition suitable for exposure with an immersion projection exposure apparatus using far ultraviolet light having a wavelength of 300 nm or less as a light source, a resin used in the resist composition, a compound used in the synthesis of the resin, and the positive The present invention relates to a pattern forming method using a mold resist composition.

With the miniaturization of semiconductor elements, the exposure light source has become shorter in wavelength and the projection lens has a higher numerical aperture (high NA). Currently, an exposure machine with NA 0.84 using an ArF excimer laser having a 193 nm wavelength as a light source has been developed. ing. These can be expressed by the following equations as is generally well known.
(Resolving power) = k ₁ · (λ / NA)
(Depth of focus) = ± k ₂ · λ / NA ²
Where λ is the wavelength of the exposure light source, NA is the numerical aperture of the projection lens, and k ₁ and k ₂ are coefficients related to the process.

An exposure machine using a F ₂ excimer laser having a wavelength of 157 nm as a light source has been studied for higher resolution by further shortening the wavelength. Lens materials and resists used in the exposure apparatus for shorter wavelength have been studied. Because the materials used in the process are very limited, it is very difficult to stabilize the manufacturing cost and quality of the apparatus and materials, and the exposure apparatus and resist that have sufficient performance and stability within the required period are not in time. The possibility is coming out.

As a technique for increasing the resolving power in an optical microscope, a so-called immersion method in which a high refractive index liquid (hereinafter also referred to as “immersion liquid”) is filled between a projection lens and a sample is known.
This “immersion effect” means that when λ ₀ is the wavelength of the exposure light in the air, n is the refractive index of the immersion liquid with respect to air, θ is the convergence angle of the light beam, and NA ₀ = sin θ. The above-described resolving power and depth of focus can be expressed by the following equations.
(Resolving power) = k ₁ · (λ ₀ / n) / NA ₀
(Depth of focus) = ± k ₂ · (λ ₀ / n) / NA ₀ ²
That is, the immersion effect is equivalent to using an exposure wavelength having a wavelength of 1 / n. In other words, in the case of a projection optical system with the same NA, the depth of focus can be increased n times by immersion.
This is effective for all pattern shapes, and can be combined with a super-resolution technique such as a phase shift method and a modified illumination method which are currently being studied.

Examples of apparatuses in which this effect is applied to transfer of a fine image pattern of a semiconductor element are introduced in Patent Document 1, Patent Document 2, and the like.
Recent progress of immersion exposure technology is reported in Non-Patent Document 1, Non-Patent Document 2, Non-Patent Document 3, Patent Document 3, and the like. In the case of using an ArF excimer laser as a light source, pure water (refractive index of 1.44 at 193 nm) is considered to be most promising as an immersion liquid in terms of handling safety, transmittance at 193 nm, and refractive index.
When an F ₂ excimer laser is used as a light source, a solution containing fluorine has been studied from the balance between transmittance and refractive index at 157 nm. However, a sufficient product has not yet been seen in terms of environmental safety and refractive index. It has not been issued. From the degree of immersion effect and the degree of completeness of the resist, the immersion exposure technique is considered to be installed in the ArF exposure machine earliest.

Since the resist for KrF excimer laser (248 nm), an image forming method called chemical amplification has been used as an image forming method for a resist in order to compensate for sensitivity reduction due to light absorption. Explaining by taking a positive chemical amplification image forming method as an example, the acid generator in the exposed area is decomposed by exposure to generate an acid upon exposure, and the generated acid is reacted as a reaction catalyst by post exposure baking (PEB). In this image forming method, an alkali-insoluble group is changed to an alkali-soluble group and an exposed portion is removed by alkali development.
Although resists for ArF excimer laser (wavelength 193 nm) using this chemical amplification mechanism are now becoming mainstream, there are still many points that are insufficient, and line edge roughness, performance difference between dense pattern and isolated pattern, especially isolated pattern It was not enough for film reduction.

In addition, when a chemically amplified resist is applied to immersion exposure, the resist layer comes into contact with the immersion liquid at the time of exposure, so that the resist layer is altered and components that adversely affect the immersion liquid are leached from the resist layer. Has been pointed out. Patent Document 4 describes an example in which resist performance is changed by immersing a resist for ArF exposure in water before and after exposure, and points out a problem in immersion exposure.
In the immersion exposure process, when exposure is performed using a scanning immersion exposure machine, the exposure speed decreases unless the immersion liquid moves following the movement of the lens. Concerned about giving. In the case where the immersion liquid is water, it is desirable that the resist film be hydrophobic so that water followability is better. On the other hand, if the resist film is hydrophobized, the amount of scum generated increases. There was also an adverse effect on performance, and improvements were desired.
JP-A-57-153433 JP-A-7-220990 JP-A-10-303114 International Publication No. 04/068242 Pamphlet Proc. SPIE, 2002, Vol. 4688, p. 11 J.Vac.Sci.Tecnol.B 17 (1999) Proc. SPIE, 2000, Vol. 3999, p. 2

  The object of the present invention is to improve the line edge roughness, the film reduction performance difference between the dense pattern and the isolated pattern, as well as the normal exposure (dry exposure) as well as the immersion exposure, reduce development defects, and suppress the occurrence of scum. Another object of the present invention is to provide a positive resist composition having good followability to immersion liquid during immersion exposure and a pattern forming method using the same.

  The present invention is a positive resist composition having the following constitution and a pattern forming method using the positive resist composition, whereby the object of the present invention is achieved.

<1>
(A) a resin whose solubility in an alkaline developer is increased by the action of an acid;
(B) a compound that generates an acid upon irradiation with an actinic ray or radiation,
(C) a hydrophobic resin having no fluorine atom or silicon atom, a molecular weight dispersity of 1.3 or less and a weight average molecular weight of 1.0 × 10 ⁴ or less, and (D) a solvent A positive resist composition characterized by comprising:

式（Ｃ−ａ）中、
Ｒ_ａは、各々独立に水素原子、または、フッ素原子及び珪素原子を含まない有機基を表す。
Ｒ_ｂは、フッ素原子及び珪素原子を含まない有機基を表す。
Ｌ_１は、単結合、または連結基を表す。 <2>
Resin (C) is resin which has a repeating unit represented by the following general formula (Ca), The positive resist composition as described in said <1> characterized by the above-mentioned.

In the formula (Ca),
R _a each independently represents a hydrogen atom or an organic group not containing a fluorine atom and a silicon atom.
R _b represents an organic group containing no fluorine atom or silicon atom.
L ₁ represents a single bond or a linking group.

式（Ｃ−Ｉ）〜（Ｃ-III）中、
Ｒ_１は、各々独立に水素原子または炭素数１〜１０のアルキル基を表す。
Ｒ_２は、炭化水素基を表す。
Ｐ_１は、単結合、またはアルキレン基、エーテル基、またはそれらを２つ以上有する連結基を表す。
Ｐ_２は、−Ｏ−、−ＮＲ−（Ｒは水素原子またはアルキル基）、−ＮＨＳＯ_２−から選ばれる連結基を表す。
ｎは１〜４の整数を表す。 <3>
The positive type as described in <1> or <2> above, wherein the resin (C) is a resin having at least one repeating unit selected from the following general formulas (CI) to (C-III): Resist composition.

In the formulas (CI) to (C-III),
R ₁ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.
R ₂ represents a hydrocarbon group.
P ₁ represents a single bond, an alkylene group, an ether group, or a linking group having two or more thereof.
P ₂ represents a linking group selected from —O—, —NR— (R is a hydrogen atom or an alkyl group), and —NHSO ₂ —.
n represents an integer of 1 to 4.

<4>
The positive resist composition according to any one of the above <1> to <3>, wherein the addition amount of the resin (C) is 0.1 to 5% by mass relative to the total solid content in the positive resist composition.

<5>
The positive resist composition according to any one of <1> to <4>, wherein the resin (C) does not have an element other than a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom.

<6>
The positive resist composition as described in <1> to <5> above, wherein the resin (C) is purified by solvent fractionation.

<7>
The positive resist composition as described in <1> to <5> above, wherein the component (C) is obtained by living radical polymerization.

<8>
The positive resist composition according to any one of the above <1> to <7>, wherein the receding contact angle of water with respect to the film formed using the positive resist composition is 70 ° or more.

  The preferred embodiments of the present invention will be further described below.

<9>
The positive resist composition as described in any one of <1> to <8> above, further comprising (E) a basic compound.

<10>
The positive resist composition as described in any one of <1> to <9> above, further comprising (F) a fluorine-based and / or silicon-based surfactant.

<11>
The positive resist composition as described in any one of <1> to <10> above, wherein the solvent (D) is a mixed solvent of two or more containing propylene glycol monomethyl ether acetate.

<12>
The positive resist composition as described in any one of <1> to <11> above, wherein the resin (A) contains a repeating unit having an alicyclic structure which is eliminated by the action of an acid.

<13>
The positive resist composition for immersion exposure according to any one of <1> to <12>, wherein the resin (A) contains a repeating unit containing a lactone group.

<14>
Resin (A) is at least a (meth) acrylate-based repeating unit having a lactone ring, a (meth) acrylate-based repeating unit having an organic group substituted with at least one of a hydroxyl group and a cyano group, and an acid-decomposable group The positive resist composition as described in any one of <1> to <13> above, which is a copolymer having three types of repeating units of (meth) acrylate-based repeating units.

<15>
<1> to <14 above, wherein the weight average molecular weight of the resin (A) is 5,000 to 15,000, and the degree of dispersion of the resin (A) is 1.2 to 3.0. > The positive resist composition according to any one of the above.

<16>
Any of <1> to <15> above, wherein the compound (B) is a compound that generates an aliphatic sulfonic acid having a fluorine atom or a benzenesulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation. A positive resist composition as described above.

<17>
The positive resist composition as described in any one of <1> to <16> above, wherein the compound (B) has a triphenylsulfonium structure.

<18>
The positive resist composition as described in <17> above, wherein the compound (B) is a triphenylsulfonium salt compound having an alkyl group or a cycloalkyl group not substituted with fluorine in the cation moiety.

<19>
The positive resist composition as described in any one of <1> to <18>, wherein the total solid content concentration in the positive resist composition is 1.0 to 6.0% by mass.

<20>
Resin (A) does not have a fluorine atom and a silicon atom, The positive resist composition in any one of said <1>-<19> characterized by the above-mentioned.

<21>
A pattern forming method comprising a step of forming a resist film from the positive resist composition according to any one of <1> to <20>, immersion exposure, and development.

<22>
The pattern forming method as described in <21> above, wherein the exposure is performed with light having a wavelength of 1 nm to 200 nm.

<23>
The pattern forming method as described in <21> or <22> above, further comprising an immersion exposure step.

  According to the present invention, it is possible to provide a positive resist composition with improved performance difference and development defect between a dense pattern and an isolated pattern. Also, a positive resist composition that has good followability to immersion liquid during immersion exposure and is suitable for immersion exposure, a resin used in the positive resist composition, and used for synthesis of the resin And a pattern forming method using the positive resist composition.

Hereinafter, the present invention will be described in detail.
In addition, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what does not have a substituent and what has a substituent. . For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

(A) Resin whose solubility in an alkaline developer is increased by the action of an acid The resin used in the positive resist composition of the present invention is a resin that decomposes by the action of an acid and increases its solubility in an alkaline developer. Resin having a group (hereinafter also referred to as “acid-decomposable group”) that decomposes by the action of an acid to generate an alkali-soluble group (hereinafter also referred to as “acid-decomposable group”) in the main chain or side chain of Or “resin (A)”).
Alkali-soluble groups include phenolic hydroxyl groups, carboxylic acid groups, fluorinated alcohol groups, sulfonic acid groups, sulfonamido groups, sulfonylimide groups, (alkylsulfonyl) (alkylcarbonyl) methylene groups, (alkylsulfonyl) (alkylcarbonyl) Imido group, bis (alkylcarbonyl) methylene group, bis (alkylcarbonyl) imide group, bis (alkylsulfonyl) methylene group, bis (alkylsulfonyl) imide group, tris (alkylcarbonyl) methylene group, tris (alkylsulfonyl) methylene group A group having
Preferred alkali-soluble groups include carboxylic acid groups, fluorinated alcohol groups (preferably hexafluoroisopropanol), and sulfonic acid groups.
A preferred group as an acid-decomposable group (acid-decomposable group) is a group obtained by substituting the hydrogen atom of these alkali-soluble groups with a group capable of leaving with an acid.
Examples of the group leaving with an acid include -C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), -C (R ₃₆ ) (R ₃₇ ) (OR ₃₉ ), -C (R ₀₁ ) (R ₀₂ ). ) (OR ₃₉ ) and the like.
In the formula, R _{36 to} R ₃₉ each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R ₃₆ and R ₃₇ may be bonded to each other to form a ring.
R _{01 and} R ₀₂ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.
The acid-decomposable group is preferably a cumyl ester group, an enol ester group, an acetal ester group, a tertiary alkyl ester group or the like. More preferably, it is a tertiary alkyl ester group.

  When irradiating the positive resist composition of the present invention with ArF excimer laser light, the resin (A) preferably contains a repeating unit having an alicyclic structure that is eliminated by the action of an acid. That is, it is preferably a resin having a monocyclic or polycyclic alicyclic hydrocarbon structure that decomposes by the action of an acid and increases the solubility in an alkali developer.

  As a resin that has a monocyclic or polycyclic alicyclic hydrocarbon structure, decomposes by the action of an acid, and increases its solubility in an alkaline developer (hereinafter also referred to as “alicyclic hydrocarbon-based acid-decomposable resin”) , At least selected from the group consisting of repeating units having a partial structure containing an alicyclic hydrocarbon represented by the following general formula (pI) to general formula (pV) and repeating units represented by the following general formula (II-AB) It is preferable that it is resin containing 1 type.

In general formulas (pI) to (pV),
R ₁₁ represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a sec-butyl group, and Z is an atom necessary for forming a cycloalkyl group together with a carbon atom. Represents a group.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or cycloalkyl group having 1 to 4 carbon atoms. However, at least one of R _{12 to} R ₁₄ , or any of R ₁₅ and R ₁₆ represents a cycloalkyl group.
R _{17 to} R ₂₁ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group. However, at least one of R _{17 to} R ₂₁ represents a cycloalkyl group. Further, either R ₁₉ or R ₂₁ represents a linear or branched alkyl group or cycloalkyl group having 1 to 4 carbon atoms.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group. However, at least one of R _{22 to} R ₂₅ represents a cycloalkyl group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

In general formula (II-AB),
R ₁₁ ′ and R ₁₂ ′ each independently represents a hydrogen atom, a cyano group, a halogen atom or an alkyl group.
Z ′ represents an atomic group for forming an alicyclic structure containing two bonded carbon atoms (C—C).

  The general formula (II-AB) is more preferably the following general formula (II-AB1) or general formula (II-AB2).

In the formulas (II-AB1) and (II-AB2),
R ₁₃ ′ to R ₁₆ ′ each independently represents a hydrogen atom, a halogen atom, a cyano group, —COOH, —COOR ₅ , a group that decomposes by the action of an acid, —C (═O) —XA′—R. ₁₇ ′ represents an alkyl group or a cycloalkyl group. At least two of R ₁₃ ′ to R ₁₆ ′ may combine to form a ring.
Here, R ₅ represents an alkyl group, a cycloalkyl group, or a group having a lactone structure.
X represents an oxygen atom, a sulfur atom, -NH -, - NHSO ₂ - or an -NHSO ₂ NH-.
A ′ represents a single bond or a divalent linking group.
R ₁₇ ′ represents —COOH, —COOR ₅ , —CN, a hydroxyl group, an alkoxy group, —CO—NH—R ₆ , —CO—NH—SO ₂ —R ₆ or a group having a lactone structure.
R ₆ represents an alkyl group or a cycloalkyl group.
n represents 0 or 1.

In the general formulas (pI) to (pV), the alkyl group in R _{12 to} R ₂₅ represents a linear or branched alkyl group having 1 to 4 carbon atoms.

The cycloalkyl group in R _{11 to} R ₂₅ or the cycloalkyl group formed by Z and the carbon atom may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 5 or more carbon atoms. The carbon number is preferably 6-30, and particularly preferably 7-25. These cycloalkyl groups may have a substituent.

  Preferred cycloalkyl groups include adamantyl group, noradamantyl group, decalin residue, tricyclodecanyl group, tetracyclododecanyl group, norbornyl group, cedrol group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, A cyclodecanyl group and a cyclododecanyl group can be mentioned. More preferable examples include an adamantyl group, norbornyl group, cyclohexyl group, cyclopentyl group, tetracyclododecanyl group, and tricyclodecanyl group.

  As further substituents of these alkyl groups and cycloalkyl groups, alkyl groups (1 to 4 carbon atoms), halogen atoms, hydroxyl groups, alkoxy groups (1 to 4 carbon atoms), carboxyl groups, alkoxycarbonyl groups (carbon numbers) 2-6). Examples of the substituent that the alkyl group, alkoxy group, alkoxycarbonyl group and the like may further have include a hydroxyl group, a halogen atom, and an alkoxy group.

  The structures represented by the general formulas (pI) to (pV) in the resin can be used for protecting alkali-soluble groups. Examples of the alkali-soluble group include various groups known in this technical field.

  Specific examples include a structure in which a hydrogen atom of a carboxylic acid group, a sulfonic acid group, a phenol group, or a thiol group is substituted with a structure represented by the general formulas (pI) to (pV), preferably a carboxylic acid Group, a hydrogen atom of a sulfonic acid group is substituted with a structure represented by general formulas (pI) to (pV).

  As the repeating unit having an alkali-soluble group protected by the structure represented by the general formulas (pI) to (pV), a repeating unit represented by the following general formula (pA) is preferable.

Here, R represents a hydrogen atom, a halogen atom, or a linear or branched alkyl group having 1 to 4 carbon atoms. A plurality of R may be the same or different.
A is a single bond, an alkylene group, an ether group, a thioether group, a carbonyl group, an ester group, an amide group, a sulfonamide group, a urethane group, or a group of two or more groups selected from the group consisting of a ureylene group. Represents. A single bond is preferable.
Rp ₁ represents any group of the above formulas (pI) to (pV).

  The repeating unit represented by the general formula (pA) is particularly preferably a repeating unit composed of 2-alkyl-2-adamantyl (meth) acrylate and dialkyl (1-adamantyl) methyl (meth) acrylate.

  Hereinafter, although the specific example of the repeating unit which has an acid-decomposable group is shown, this invention is not limited to this.

Examples of the halogen atom in the general formula (II-AB), R ₁₁ ′, and R ₁₂ ′ include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom.

Examples of the alkyl group in R ₁₁ ′ and R ₁₂ ′ include a linear or branched alkyl group having 1 to 10 carbon atoms.

  The atomic group for forming the alicyclic structure of Z ′ is an atomic group that forms a repeating unit of an alicyclic hydrocarbon which may have a substituent in a resin, and among them, a bridged type alicyclic group. An atomic group for forming a bridged alicyclic structure forming a cyclic hydrocarbon repeating unit is preferred.

Examples of the alicyclic hydrocarbon skeleton to be formed include the same alicyclic hydrocarbon groups as R _{12 to} R _{25 in} the general formulas (pI) to (pV).

The alicyclic hydrocarbon skeleton may have a substituent. Examples of such a substituent include R ₁₃ ′ to R ₁₆ ′ in the general formula (II-AB1) or (II-AB2).

  In the alicyclic hydrocarbon-based acid-decomposable resin according to the present invention, the group decomposed by the action of an acid has a partial structure containing the alicyclic hydrocarbon represented by the general formula (pI) to the general formula (pV). It can be contained in at least one kind of repeating unit among the repeating unit having, the repeating unit represented by formula (II-AB), and the repeating unit of the copolymerization component described later.

Various substituents of R ₁₃ ′ to R ₁₆ ′ in the general formula (II-AB1) or the general formula (II-AB2) are atomic groups for forming an alicyclic structure in the general formula (II-AB). It can also be a substituent of the atomic group Z for forming a bridged alicyclic structure.

  Specific examples of the repeating unit represented by the general formula (II-AB1) or (II-AB2) include the following specific examples, but the present invention is not limited to these specific examples.

  The acid-decomposable resin (A) of the present invention preferably contains a repeating unit having a lactone group. As the lactone group, any group can be used as long as it contains a lactone structure, but preferably a group containing a 5- to 7-membered ring lactone structure, and a bicyclo structure in the 5- to 7-membered ring lactone structure, Those in which other ring structures are condensed to form a spiro structure are preferred. It is more preferable to have a repeating unit having a group having a lactone structure represented by any of the following general formulas (LC1-1) to (LC1-16). Further, a group having a lactone structure may be directly bonded to the main chain. Preferred lactone structures are groups represented by general formulas (LC1-1), (LC1-4), (LC1-5), (LC1-6), (LC1-13), (LC1-14), By using a specific lactone structure, line edge roughness and development defects are improved.

The lactone structure moiety may or may not have a substituent (Rb ₂ ). Preferred substituents (Rb ₂ ) include an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 4 to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkoxycarbonyl group having 1 to 8 carbon atoms, and a carboxyl group. , Halogen atom, hydroxyl group, cyano group, acid-decomposable group and the like. n ₂ represents an integer of 0-4. When n ₂ is 2 or more, a plurality of Rb ₂ may be the same or different, and a plurality of Rb ₂ may be bonded to form a ring.

As the repeating unit having a group having a lactone structure represented by any of the general formulas (LC1-1) to (LC1-16), R _{13 in the} above general formula (II-AB1) or (II-AB2) may be used. Wherein at least one of 'to R ₁₆ ' has a group represented by the general formulas (LC1-1) to (LC1-16) (for example, R _{5 of} -COOR ₅ is represented by the general formulas (LC1-1) to (LC1) -16) or a repeating unit represented by the following general formula (AI).

In general formula (AI),
Rb ₀ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.
Preferable substituents that the alkyl group of Rb ₀ may have include a hydroxyl group and a halogen atom.
Examples of the halogen atom for Rb ₀ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Rb ₀ is preferably a hydrogen atom or a methyl group.
Ab represents a single bond, an alkylene group, a divalent linking group having a monocyclic or polycyclic alicyclic hydrocarbon structure, an ether group, an ester group, a carbonyl group, a carboxyl group, or a divalent group obtained by combining these. To express. A linking group represented by a single bond or —Ab ₁ —CO ₂ — is preferable.
Ab ₁ is a linear, branched alkylene group, monocyclic or polycyclic cycloalkylene group, preferably a methylene group, an ethylene group, a cyclohexylene group, an adamantylene group or a norbornylene group.
V represents a group represented by any one of the general formulas (LC1-1) to (LC1-16).

  The repeating unit having a lactone structure usually has an optical isomer, but any optical isomer may be used. One optical isomer may be used alone, or a plurality of optical isomers may be mixed and used. When one kind of optical isomer is mainly used, the optical purity (ee) thereof is preferably 90 or more, more preferably 95 or more.

  Specific examples of the repeating unit having a group having a lactone structure are given below, but the present invention is not limited thereto.

The acid-decomposable resin (A) of the present invention preferably has a repeating unit containing an organic group having a polar group, particularly a repeating unit having an alicyclic hydrocarbon structure substituted with a polar group. This improves the substrate adhesion and developer compatibility. The alicyclic hydrocarbon structure of the alicyclic hydrocarbon structure substituted with a polar group is preferably an adamantyl group, a diamantyl group, or a norbornane group. The polar group is preferably a hydroxyl group or a cyano group.
As the alicyclic hydrocarbon structure substituted with a polar group, partial structures represented by the following general formulas (VIIa) to (VIId) are preferable.

In general formulas (VIIa) to (VIIc),
R _{2c to} R _4c each independently represents a hydrogen atom, a hydroxyl group or a cyano group. However, at least one of R _{2c to} R _4c represents a hydroxyl group or a cyano group. Preferably, one or two of R _{2c to} R _4c are a hydroxyl group and the rest are hydrogen atoms.
In general formula (VIIa), it is more preferable that two members out of R _{2c to} R _4c are a hydroxyl group and the remaining is a hydrogen atom.

As the repeating unit having a group represented by the general formulas (VIIa) to (VIId), at least one of R ₁₃ ′ to R ₁₆ ′ in the general formula (II-AB1) or (II-AB2) is the above. And a repeating unit represented by the following general formulas (AIIa) to (AIId): a group represented by general formulas (VIIa) to (VIId).

In general formulas (AIIa) to (AIId),
R _1c represents a hydrogen atom, a methyl group, a trifluoromethyl group, or a hydroxymethyl group.
R _2c to R _4c have the same meanings as R _2c to R _4c in formulas (VIIa) ~ (VIIc).

  Although the specific example of the repeating unit which has a structure represented by general formula (AIIa)-(AIId) is given to the following, this invention is not limited to these.

  The acid-decomposable resin (A) of the present invention may have a repeating unit represented by the following general formula (VIII).

In the above general formula (VIII),
Z ₂ represents —O— or —N (R ₄₁ ) —. R ₄₁ represents a hydrogen atom, a hydroxyl group, an alkyl group, or —OSO ₂ —R ₄₂ . R ₄₂ represents an alkyl group, a cycloalkyl group or a camphor residue. The alkyl group of R ₄₁ and R ₄₂ may be substituted with a halogen atom (preferably a fluorine atom) or the like.

  Examples of the repeating unit represented by the general formula (VIII) include the following specific examples, but the present invention is not limited thereto.

  The acid-decomposable resin (A) of the present invention preferably has a repeating unit having an alkali-soluble group, and more preferably has a repeating unit having a carboxyl group. By containing this, the resolution in contact hole applications increases. The repeating unit having a carboxyl group includes a repeating unit in which a carboxyl group is directly bonded to the main chain of the resin, such as a repeating unit of acrylic acid or methacrylic acid, or a carboxyl group in the main chain of the resin through a linking group. Either a repeating unit that is bonded, or a polymerization initiator or chain transfer agent having an alkali-soluble group is introduced at the end of the polymer chain at the time of polymerization, and the linking group is a monocyclic or polycyclic hydrocarbon. You may have a structure. Particularly preferred are repeating units of acrylic acid or methacrylic acid.

  The acid-decomposable resin (A) of the present invention may further have a repeating unit having 1 to 3 groups represented by the general formula (F1). This improves line edge roughness performance.

In general formula (F1),
R _{50 to} R ₅₅ each independently represents a hydrogen atom, a fluorine atom or an alkyl group. However, at least one of R _{50 to} R ₅₅ represents a fluorine atom or an alkyl group in which at least one hydrogen atom is substituted with a fluorine atom.
Rx represents a hydrogen atom or an organic group (preferably an acid-decomposable protecting group, an alkyl group, a cycloalkyl group, an acyl group, or an alkoxycarbonyl group).

The alkyl group of R _{50 to} R ₅₅ may be substituted with a halogen atom such as a fluorine atom, a cyano group, etc., preferably an alkyl group having 1 to 3 carbon atoms, such as a methyl group or a trifluoromethyl group. be able to.
R _{50 to} R ₅₅ are preferably all fluorine atoms.

  Examples of the organic group represented by Rx include an acid-decomposable protective group and an optionally substituted alkyl group, cycloalkyl group, acyl group, alkylcarbonyl group, alkoxycarbonyl group, alkoxycarbonylmethyl group, alkoxymethyl group. , 1-alkoxyethyl group is preferable.

  The repeating unit having a group represented by the general formula (F1) is preferably a repeating unit represented by the following general formula (F2).

In general formula (F2),
Rx represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. Preferable substituents that the alkyl group of Rx may have include a hydroxyl group and a halogen atom.
Fa represents a single bond or a linear or branched alkylene group (preferably a single bond).
Fb represents a monocyclic or polycyclic hydrocarbon group.
Fc represents a single bond or a linear or branched alkylene group (preferably a single bond or a methylene group).
F ₁ represents a group represented by the general formula (F1).
P ₁ represents a 1 to 3.
The cyclic hydrocarbon group in Fb is preferably a cyclopentyl group, a cyclohexyl group, or a norbornyl group.

  Specific examples of the repeating unit having a group represented by the general formula (F1) are shown below, but the present invention is not limited thereto.

  The acid-decomposable resin (A) of the present invention may further contain a repeating unit that has an alicyclic hydrocarbon structure and does not exhibit acid-decomposability. This can reduce the elution of low molecular components from the resist film to the immersion liquid during immersion exposure. Examples of such a repeating unit include 1-adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, and cyclohexyl (meth) acrylate.

  In addition to the above repeating structural units, the acid-decomposable resin (A) of the present invention has dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and resolution and heat resistance, which are general necessary characteristics of resist. Various repeating structural units can be contained for the purpose of adjusting properties, sensitivity and the like.

  Examples of such repeating structural units include, but are not limited to, repeating structural units corresponding to the following monomers.

  Thereby, the performance required for the acid-decomposable resin (A), in particular, (1) solubility in coating solvent, (2) film-formability (glass transition temperature), (3) alkali developability, (4) film Fine adjustments such as slippage (hydrophobic and hydrophobic group selection), (5) adhesion of unexposed portions to the substrate, and (6) dry etching resistance are possible.

  As such a monomer, for example, a compound having one addition polymerizable unsaturated bond selected from acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, etc. Etc.

  In addition, any addition-polymerizable unsaturated compound that can be copolymerized with monomers corresponding to the above various repeating structural units may be copolymerized.

  In the acid-decomposable resin (A), the content molar ratio of each repeating structural unit is the resist pattern dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and resolving power, which is a general required performance of the resist, It is appropriately set for adjusting heat resistance, sensitivity, and the like.

Preferred embodiments of the acid-decomposable resin (A) of the present invention include the following.
(1) What contains the repeating unit which has a partial structure containing the alicyclic hydrocarbon represented by said general formula (pI)-(pV) (side chain type).
Preferably those containing (meth) acrylate repeating units having a structure of (pI) to (pV).
(2) One containing a repeating unit represented by the general formula (II-AB) (main chain type).
However, in (2), for example, the following can be further mentioned.
(3) A repeating unit represented by the general formula (II-AB), a maleic anhydride derivative and a (meth) acrylate structure (hybrid type).

  In the acid-decomposable resin (A), the content of the repeating unit having an acid-decomposable group is preferably 10 to 60 mol%, more preferably 20 to 50 mol%, still more preferably 25 to 40 in all repeating structural units. Mol%.

  In the acid-decomposable resin (A), the content of the repeating unit having a partial structure containing the alicyclic hydrocarbon represented by the general formulas (pI) to (pV) is 20 to 70 mol% in all repeating structural units. Is preferable, more preferably 20 to 50 mol%, still more preferably 25 to 40 mol%.

  In the acid-decomposable resin (A), the content of the repeating unit represented by the general formula (II-AB) is preferably from 10 to 60 mol%, more preferably from 15 to 55 mol%, more preferably from all repeating structural units. Preferably it is 20-50 mol%.

In the acid-decomposable resin (A), the content of the repeating unit having a lactone ring is preferably 10 to 70 mol%, more preferably 20 to 60 mol%, still more preferably 25 to 40 mol% in all repeating structural units. It is.
In the acid-decomposable resin (A), the content of the repeating unit having an organic group having a polar group is preferably 1 to 40 mol%, more preferably 5 to 30 mol%, still more preferably 5 in all repeating structural units. ~ 20 mol%.

  Further, the content of the repeating structural unit based on the monomer of the further copolymer component in the resin can also be appropriately set according to the desired performance. Generally, the general formula (pI) to 99 mol% or less based on the total number of moles of the repeating structural unit having a partial structure containing an alicyclic hydrocarbon represented by (pV) and the repeating unit represented by the above general formula (II-AB) More preferably, it is 90 mol% or less, More preferably, it is 80 mol% or less.

  When the positive resist composition of the present invention is for ArF exposure, the resin (A) preferably has no aromatic group from the viewpoint of transparency to ArF light.

  The acid-decomposable resin (A) used in the present invention is preferably one in which all of the repeating units are composed of (meth) acrylate-based repeating units. In this case, all of the repeating units may be methacrylate repeating units, all of the repeating units may be acrylate repeating units, and all of the repeating units may be any mixture of methacrylate repeating units / acrylate repeating units, It is preferable that the acrylate repeating unit is 50 mol% or less of the entire repeating unit.

  The acid-decomposable resin (A) includes at least a (meth) acrylate-based repeating unit having a lactone ring, a (meth) acrylate-based repeating unit having an organic group substituted with at least one of a hydroxyl group and a cyano group, and an acid A copolymer having three types of repeating units of a (meth) acrylate-based repeating unit having a degradable group is preferable.

  Preferably, 20 to 50 mol% of repeating units having a partial structure containing an alicyclic hydrocarbon represented by general formulas (pI) to (pV), 20 to 50 mol% of repeating units having a lactone structure, substituted with a polar group It is a ternary copolymer containing 5 to 30% of repeating units having an alicyclic hydrocarbon structure, or a quaternary copolymer containing 0 to 20% of other repeating units.

  Particularly preferable resins include 20 to 50 mol% of repeating units having an acid-decomposable group represented by the following general formulas (ARA-1) to (ARA-5), and the following general formulas (ARL-1) to (ARL- 6) 50 to 50 mol% of a repeating unit having a lactone group represented by formula (6), and a repeating unit having an alicyclic hydrocarbon structure substituted with a polar group represented by the following general formulas (ARH-1) to (ARH-3) A ternary copolymer containing 5 to 30 mol% of units, or a carboxyl group, or a repeating unit having a structure represented by the general formula (F1), having an alicyclic hydrocarbon structure and not exhibiting acid decomposability It is a quaternary copolymer containing 5 to 20 mol% of repeating units.

(In the formula, Rxy and Rxy ₁ represent a hydrogen atom or a methyl group, and Rxa ₁ and Rxb ₁ represent a methyl group or an ethyl group.)

  The acid-decomposable resin (A) used in the present invention can be synthesized according to a conventional method (for example, radical polymerization). For example, as a general synthesis method, a monomer polymerization method in which a monomer species and an initiator are dissolved in a solvent and the polymerization is performed by heating, and a solution of the monomer species and the initiator is dropped into the heating solvent over 1 to 10 hours. The dropping polymerization method is added, and the dropping polymerization method is preferable. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane, diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, amide solvents such as dimethylformamide and dimethylacetamide, Furthermore, the solvent which melt | dissolves the composition of this invention like the below-mentioned propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone is mentioned. More preferably, the polymerization is performed using the same solvent as the solvent used in the positive resist composition of the present invention. Thereby, the generation of particles during storage can be suppressed.

The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. As a polymerization initiator, a commercially available radical initiator (azo initiator, peroxide, etc.) is used to initiate the polymerization. As the radical initiator, an azo initiator is preferable, and an azo initiator having an ester group, a cyano group, or a carboxyl group is preferable. Preferred examples of the initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile, dimethyl 2,2′-azobis (2-methylpropionate) and the like. If desired, an initiator is added or added in portions, and after completion of the reaction, it is put into a solvent and a desired polymer is recovered by a method such as powder or solid recovery. The concentration of the reaction is 5 to 50% by mass, preferably 10 to 30% by mass.
The reaction temperature is usually 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, more preferably 60-100 ° C.

The weight average molecular weight of the resin (A) according to the present invention is preferably 1,000 to 200,000, more preferably 3,000 to 20,000, most preferably 5, as a polystyrene conversion value by GPC method. 000 to 15,000. By setting the weight average molecular weight to 1,000 to 200,000, deterioration of heat resistance and dry etching resistance can be prevented, developability is deteriorated, and viscosity is increased, resulting in deterioration of film forming property. Can be prevented.
The degree of dispersion (molecular weight distribution) is usually 1 to 5, preferably 1 to 3, more preferably 1.2 to 3.0, particularly preferably 1.2 to 2.0. . The smaller the degree of dispersion, the better the resolution and the resist shape, the smoother the side wall of the resist pattern, and the better the roughness.

In the positive resist composition of the present invention, the blending amount of all the resins according to the present invention in the entire composition is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass in the total solid content. %.
In the present invention, the resins may be used alone or in combination.

  The acid-decomposable resin (A) of the present invention preferably contains no fluorine atom or silicon atom from the viewpoint of compatibility with the resin (C).

(B) Compound that generates acid upon irradiation with actinic ray or radiation The positive resist composition of the present invention is a compound that generates acid upon irradiation with actinic ray or radiation ("photoacid generator" or "component (B)") (Also called).
Examples of such photoacid generators include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, actinic rays used in microresists, etc. Known compounds that generate an acid upon irradiation with radiation and mixtures thereof can be appropriately selected and used.

  Examples thereof include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

  Further, a group that generates an acid upon irradiation with these actinic rays or radiation, or a compound in which a compound is introduced into the main chain or side chain of the polymer, such as US Pat. No. 3,849,137, German Patent No. No. 3914407, JP-A 63-26653, JP-A 55-164824, JP-A 62-69263, JP-A 63-146038, JP-A 63-163452, The compounds described in JP-A-62-153853 and JP-A-63-146029 can be used.

  Furthermore, compounds capable of generating an acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

  Among the compounds that decompose upon irradiation with actinic rays or radiation to generate an acid, compounds represented by the following general formulas (ZI), (ZII), and (ZIII) can be exemplified.

In the above general formula (ZI), R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
X ⁻ represents a non-nucleophilic anion, preferably sulfonate anion, carboxylate anion, bis (alkylsulfonyl) amide anion, tris (alkylsulfonyl) methide anion, BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ^{− and the} like. Preferably, it is an organic anion containing a carbon atom.

  Preferable organic anions include organic anions represented by the following formula.

Where
Rc ₁ represents an organic group.
Examples of the organic group in Rc ₁ include those having 1 to 30 carbon atoms, and preferably an alkyl group, an aryl group, or a plurality thereof, which may be substituted, is a single bond, —O—, —CO ₂ —, — Examples include groups linked by a linking group such as S-, -SO _3- , -SO ₂ N (Rd ₁ )-. Rd ₁ represents a hydrogen atom or an alkyl group.
Rc ₃ , Rc ₄ and Rc ₅ each independently represents an organic group. Preferred examples of the organic group for Rc ₃ , Rc ₄ , and Rc ₅ include the same organic groups as those for Rc _1, and a perfluoroalkyl group having 1 to 4 carbon atoms is most preferred.
Rc ₃ and Rc ₄ may combine to form a ring. Examples of the group formed by combining Rc ₃ and Rc ₄ include an alkylene group and an arylene group. Preferably, it is a C2-C4 perfluoroalkylene group.
The organic group of Rc ₁ and Rc _{3 to} Rc ₅ is particularly preferably an alkyl group substituted at the 1-position with a fluorine atom or a fluoroalkyl group, or a phenyl group substituted with a fluorine atom or a fluoroalkyl group. By having a fluorine atom or a fluoroalkyl group, the acidity of the acid generated by light irradiation is increased and the sensitivity is improved. Further, when Rc ₃ and Rc ₄ are combined to form a ring, the acidity of the acid generated by light irradiation is increased, and the sensitivity is improved.

The carbon number of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ is generally 1-30, preferably 1-20.
Two of R _{201 to} R ₂₀₃ may be bonded to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. The two of the group formed by bonding of the R ₂₀₁ to R _203, there can be mentioned an alkylene group (e.g., butylene, pentylene).
Specific examples of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ include corresponding groups in the compounds (ZI-1), (ZI-2) and (ZI-3) described later.

In addition, the compound which has two or more structures represented by general formula (ZI) may be sufficient. For example, the general formula at least one of R ₂₀₁ to R ₂₀₃ of a compound represented by (ZI) is, at least one bond with structure of R ₂₀₁ to R ₂₀₃ of another compound represented by formula (ZI) It may be a compound.

  More preferable (ZI) components include compounds (ZI-1), (ZI-2), and (ZI-3) described below.

The compound (ZI-1) is at least one of the aryl groups R ₂₀₁ to R ₂₀₃ in formula (ZI), arylsulfonium compound, i.e., a compound having arylsulfonium as a cation.
In the arylsulfonium compound, all of R _{201 to} R ₂₀₃ may be an aryl group, or a part of R _{201 to} R ₂₀₃ may be an aryl group, and the rest may be an alkyl group or a cycloalkyl group.
Examples of the arylsulfonium compound include triarylsulfonium compounds, diarylalkylsulfonium compounds, aryldialkylsulfonium compounds, diarylcycloalkylsulfonium compounds, and aryldicycloalkylsulfonium compounds.
The aryl group of the arylsulfonium compound is preferably an aryl group such as a phenyl group or a naphthyl group, or a heteroaryl group such as an indole residue or a pyrrole residue, more preferably a phenyl group or an indole residue. When the arylsulfonium compound has two or more aryl groups, the two or more aryl groups may be the same or different.
The alkyl group that the arylsulfonium compound has as necessary is preferably a linear or branched alkyl group having 1 to 15 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, sec- Examples thereof include a butyl group and a t-butyl group.
The cycloalkyl group that the arylsulfonium compound has as necessary is preferably a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.
Aryl group, alkyl group of R ₂₀₁ to R _203, cycloalkyl group, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 6 to 14 carbon atoms) , An alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, or a phenylthio group may be substituted. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and linear, branched or cyclic alkoxy groups having 1 to 12 carbon atoms, and particularly preferable. Is an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R _{201 to} R ₂₀₃ , or may be substituted with all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Next, the compound (ZI-2) will be described. Compound (ZI-2) is a compound in the case where R _{201 to} R ₂₀₃ in formula (ZI) each independently represents an organic group containing no aromatic ring. Here, the aromatic ring includes an aromatic ring containing a hetero atom.
The organic group having no aromatic ring as R ₂₀₁ to R ₂₀₃ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
R _{201 to} R ₂₀₃ are each independently preferably an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group, more preferably a linear, branched, cyclic 2-oxoalkyl group, or an alkoxycarbonylmethyl group, particularly preferably Is a linear, branched 2-oxoalkyl group.

The alkyl group as R ₂₀₁ to R ₂₀₃ may be linear, it may be either branched, preferably a straight-chain or branched alkyl group (e.g., methyl group having 1 to 10 carbon atoms, an ethyl group, a propyl Group, butyl group, pentyl group). The alkyl group as R ₂₀₁ to R ₂₀₃ is a straight-chain or branched 2-oxoalkyl group is preferably an alkoxycarbonyl methyl group.
The cycloalkyl group as R ₂₀₁ to R ₂₀₃ is preferably, and a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl).
The cycloalkyl group as R ₂₀₁ to R ₂₀₃ is preferably a cyclic 2-oxoalkyl group.
Linear as R ₂₀₁ to R _203, branched or cyclic 2-oxoalkyl group may preferably be a group having a 2-position> C = O in the above-described alkyl or cycloalkyl group.
The alkoxy group in the alkoxycarbonylmethyl group as R ₂₀₁ to R _203, preferably may be mentioned alkoxy groups having 1 to 5 carbon atoms (a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group).
R _{201 to} R ₂₀₃ may be further substituted with a halogen atom, an alkoxy group (for example, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, or a nitro group.

  The compound (ZI-3) is a compound represented by the following general formula (ZI-3), and is a compound having a phenacylsulfonium salt structure.

In general formula (ZI-3),
R _{1c to} R _5c each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, or a halogen atom.
R _6c and R _7c each independently represents a hydrogen atom, an alkyl group or a cycloalkyl group.
Rx and Ry each independently represents an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group.
Any two or more of R _1c to R _7c, and R _x and R _y may be bonded to each other to form a ring structure, the ring structure may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond May be included. Examples of the group formed by combining any two or more of R _{1c to} R _7c and R _x and R _y include a butylene group and a pentylene group.
X ⁻ represents a non-nucleophilic anion, and examples thereof include the same non-nucleophilic anion as X ^{− in} formula (ZI).

The alkyl group as R _{1c to} R _7c may be either linear or branched, for example, a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms. Or a linear or branched alkyl group (for example, a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, or a linear or branched pentyl group).
The cycloalkyl group as R _{1c to} R _7c is preferably a cycloalkyl group having 3 to 8 carbon atoms (for example, a cyclopentyl group or a cyclohexyl group).
The alkoxy group as R _{1c to} R _{5c may} be linear, branched or cyclic, for example, an alkoxy group having 1 to 10 carbon atoms, preferably a linear or branched alkoxy group having 1 to 5 carbon atoms. (For example, methoxy group, ethoxy group, linear or branched propoxy group, linear or branched butoxy group, linear or branched pentoxy group), C3-C8 cyclic alkoxy group (for example, cyclopentyloxy group, cyclohexyloxy group) ).
Preferably, any one of R _{1c to} R _5c is a linear or branched alkyl group, a cycloalkyl group, or a linear, branched or cyclic alkoxy group, and more preferably the sum of the carbon number of R _{1c to} R _5c is 2 ~ 15. Thereby, solvent solubility improves more and generation | occurrence | production of a particle is suppressed at the time of a preservation | save.

_Examples of the alkyl group as R _x and R _y include the same alkyl groups as R _{1c to} R _7c . The alkyl group as R _x and R _y is preferably a linear or branched 2-oxoalkyl group or an alkoxycarbonylmethyl group.
The cycloalkyl group as R _x and R _y may be the same as the cycloalkyl group as R _1c to R _7c. The cycloalkyl group as R _x and R _y is preferably a cyclic 2-oxoalkyl group.
Examples of the linear, branched, or cyclic 2-oxoalkyl group include a group having> C═O at the 2-position of the alkyl group or cycloalkyl group as R _{1c to} R _7c .
Examples of the alkoxy group in the alkoxycarbonylmethyl group include the same alkoxy groups as R _{1c to} R _5c .
R _x and R _y are preferably an alkyl group having 4 or more carbon atoms, more preferably 6 or more, and still more preferably 8 or more.

In general formulas (ZII) and (ZIII),
R ₂₀₄ to R ₂₀₇ each independently represents an aryl group, an alkyl group or a cycloalkyl group.
Phenyl group and a naphthyl group are preferred as the aryl group of R ₂₀₄ to R _207, more preferably a phenyl group.
The alkyl group as R ₂₀₄ to R ₂₀₇ may be linear, it may be either branched, preferably a straight-chain or branched alkyl group (e.g., methyl group having 1 to 10 carbon atoms, an ethyl group, a propyl Group, butyl group, pentyl group).
The cycloalkyl group as R ₂₀₄ to R ₂₀₇ is preferably, and a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl).
R ₂₀₄ to R ₂₀₇ may have a substituent. The R ₂₀₄ to R ₂₀₇ are substituents which may have, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (e.g., 6 carbon atoms 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups and the like.
X ⁻ represents a non-nucleophilic anion, and examples thereof include the same non-nucleophilic anion as X ^{− in} formula (ZI).

  Among the compounds that generate an acid upon irradiation with actinic rays or radiation, compounds represented by the following general formulas (ZIV), (ZV), and (ZVI) can be further exemplified.

In general formulas (ZIV) to (ZVI),
Ar ₃ and Ar ₄ each independently represents an aryl group.
R ₂₀₆ represents an alkyl group or an aryl group.
R ₂₀₇ and R ₂₀₈ each independently represents an alkyl group, an aryl group, or an electron withdrawing group.
R ₂₀₇ is preferably an aryl group.
R ₂₀₈ is preferably an electron withdrawing group, more preferably a cyano group or a fluoroalkyl group.
A represents an alkylene group, an alkenylene group or an arylene group.

  As the compound that generates an acid upon irradiation with actinic rays or radiation, compounds represented by general formulas (ZI) to (ZIII) are preferable.

  The compound (B) is preferably a compound that generates an aliphatic sulfonic acid having a fluorine atom or a benzenesulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation.

  The compound (B) preferably has a triphenylsulfonium structure.

  The compound (B) is preferably a triphenylsulfonium salt compound having an alkyl group or a cycloalkyl group not substituted with fluorine in the cation moiety.

  Among the compounds that generate an acid upon irradiation with actinic rays or radiation, examples of particularly preferable compounds are listed below.

A photo-acid generator can be used individually by 1 type or in combination of 2 or more types. When two or more types are used in combination, it is preferable to combine two types of compounds that generate two types of organic acids that differ in the total number of atoms excluding hydrogen atoms by two or more.
The content of the photoacid generator is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 7% by mass, based on the total solid content of the positive resist composition. It is.

(C) Hydrophobic resin The positive resist composition of the present invention contains a hydrophobic resin (C). As a result, the hydrophobic resin (C) is unevenly distributed on the surface of the resist film, and when the immersion medium is water, the receding contact angle of the resist film surface with respect to water when the resist film is formed is improved, and the immersion water followability is improved. Can be made. As the hydrophobic resin (C), any resin can be used as long as the receding contact angle of the surface can be improved by addition. The receding contact angle of the resist film is 60 ° to 80 °, preferably 70 ° or more. The addition amount can be adjusted as appropriate so that the receding contact angle of the resist film falls within the above range, but is preferably 0.1 to 20% by mass, more preferably, based on the total solid content of the resist composition. Is 0.1 to 10% by mass, more preferably 0.1 to 5% by mass.
The hydrophobic resin (C) is ubiquitous at the interface as described above, but unlike the surfactant (F), it is not always necessary to have a hydrophilic group in the molecule, and the polar / nonpolar substance is uniform. It is not necessary to contribute to mixing.

The resist composition of the present invention contains a hydrophobic resin (C) that makes the surface hydrophobic.
Resin (C) is a hydrophobic resin having neither fluorine atoms nor silicon atoms.
The resin (C) is preferably a resin having a repeating unit represented by the following general formula (Ca).

In the formula (Ca),
R _a each independently represents a hydrogen atom or an organic group having no fluorine atom and silicon atom.
R _b represents an organic group having no fluorine atom and no silicon atom.
L ₁ represents a single bond or a linking group.

The organic group having no fluorine atom and no silicon atom for _Ra is preferably a cyano group, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent, an alkyloxy group, A cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, and an aralkyl group.
The organic group having no fluorine atom and no silicon atom for R _b is preferably a linear, branched, or cyclic alkyl group, alkyloxy group, cyclohexane having 1 to 30 carbon atoms that may have a cyano group substituent. An alkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, and an aralkyl group;
As the linking group for L ₁ , alkylene, —O—, —COO—, —CONR— (R is a hydrogen atom or alkyl), —NR— (R is a hydrogen atom or alkyl), —NHSO ₂ — or It is a group having two or more.
R _{a s} or R _a and R _b may be bonded to each other to form a ring.
When R _a or R _a and R _b are bonded to each other to form a ring, the structure is preferably the same as the repeating unit represented by the formula (II-AB) in the resin (A).

  The resin (C) is more preferably a resin having a repeating unit selected from the following general formulas (CI) to (C-III).

In the formulas (CI) to (C-III),
R ₁ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.
R ₂ represents a hydrocarbon group.
P ₁ represents a single bond, an alkylene group, an ether group, or a linking group having two or more thereof.
P ₂ represents a linking group selected from —O—, —NR— (R is a hydrogen atom or an alkyl group), and —NHSO ₂ —.
n represents an integer of 1 to 4.
These repeating units may be one or a plurality of repeating units may be combined.

R ₂ hydrocarbon group in formulas (CI) to (C-III) Preferably has one or more —CH ₃ partial structures (ie, methyl groups). Examples of the hydrocarbon group for R ₂ include alkyl groups, alkyloxy groups, alkyl-substituted cycloalkyl groups, alkenyl groups, alkyl-substituted alkenyl groups, alkyl-substituted cycloalkenyl groups, alkyl-substituted aryl groups, and alkyl-substituted aralkyl groups. Group, an alkyl-substituted cycloalkyl group is preferred. The hydrocarbon group for R ₂ more preferably has two or more —CH ₃ partial structures.

The alkyl group in R ₂ is preferably a branched linear or branched alkyl group having 1 to 20 carbon atoms. Specific examples of preferred alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, isopropyl, isobutyl, t-butyl, 3 -Pentyl group, 2-methyl-3-butyl group, 3-hexyl group, 2-methyl-3-pentyl group, 3-methyl-4-hexyl group, 3,5-dimethyl-4-pentyl group, isooctyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2,3,5,7-tetramethyl-4-heptyl group, etc. Is mentioned. More preferably, an isobutyl group, a t-butyl group, a 2-methyl-3-butyl group, a 2-methyl-3-pentyl group, a 3-methyl-4-hexyl group, a 3,5-dimethyl-4-pentyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2,3,5,7-tetramethyl-4-heptyl group is there.

Examples of the alkyloxy group having at least one —CH ₃ partial structure in R ₂ include groups in which an ether group is bonded to an alkyl group having at least two —CH ₃ partial structures.

The cycloalkyl group in R ₂ may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 5 or more carbon atoms. The carbon number is preferably 6-30, and particularly preferably 7-25.
Preferred cycloalkyl groups include adamantyl group, noradamantyl group, decalin residue, tricyclodecanyl group, tetracyclododecanyl group, norbornyl group, cedrol group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, A cyclodecanyl group and a cyclododecanyl group can be mentioned. More preferable examples include an adamantyl group, norbornyl group, cyclohexyl group, cyclopentyl group, tetracyclododecanyl group, and tricyclodecanyl group. More preferably, they are a norbornyl group, a cyclopentyl group, and a cyclohexyl group.
The alkenyl group in R ₂ is preferably a linear or branched alkenyl group having 1 to 20 carbon atoms, and more preferably a branched alkenyl group.
The aryl group in R ₂ is preferably an aryl group having 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group, and a phenyl group is preferable.
The aralkyl group in R ₂ is preferably an aralkyl group having 7 to 12 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group.

Specific examples of the hydrocarbon group having at least two —CH ₃ partial structures in the general formulas (CI) to (C-III) and R ₂ include isopropyl group, isobutyl group, t- Butyl group, 3-pentyl group, 2-methyl-3-butyl group, 3-hexyl group, 2,3-dimethyl-2-butyl group, 2-methyl-3-pentyl group, 3-methyl-4-hexyl group 3,5-dimethyl-4-pentyl group, isooctyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2 , 3,5,7-tetramethyl-4-heptyl group, 3,5-dimethylcyclohexyl group, 4-isopropylcyclohexyl group, 4-tbutylcyclohexyl group, isobornyl group and the like. More preferably, an isobutyl group, a t-butyl group, a 2-methyl-3-butyl group, a 2,3-dimethyl-2-butyl group, a 2-methyl-3-pentyl group, a 3-methyl-4-hexyl group, 3,5-dimethyl-4-pentyl group, 2,4,4-trimethylpentyl group, 2-ethylhexyl group, 2,6-dimethylheptyl group, 1,5-dimethyl-3-heptyl group, 2,3,5 , 7-tetramethyl-4-heptyl group, 3,5-dimethylcyclohexyl group, 4-isopropylcyclohexyl group, 4-tbutylcyclohexyl group and isobornyl group.

  The total content of repeating units selected from the general formulas (CI) to (C-III) is preferably 50 to 100 mol%, more preferably 80 to 100 mol%, still more preferably based on all repeating units in the polymer. Is 90 to 100 mol%.

  Preferable specific examples of the repeating unit represented by formula (CI) are listed below. Note that the present invention is not limited to this.

The repeating unit represented by the general formula (CI) is preferably copolymerized with an electron-accepting monomer. Examples of the electron accepting monomer include maleic anhydride, fumaronitrile, maleimide, p-nitrostyrene, and the like. Preferably, maleic anhydride and maleimide are used.
Below, the example of the combination of the repeating unit represented by a formula (CI) and the repeating unit corresponding to an electron-accepting monomer is shown.

  Preferred specific examples of the repeating unit represented by formula (C-II) are shown below. Note that the present invention is not limited to this.

In general formula (C-III), when P ₂ is an oxygen atom, the carbon atom directly connected to the oxygen atom is preferably secondary or tertiary.
Specific preferred examples of the repeating unit represented by formula (C-III) are shown below. Note that the present invention is not limited to this. In specific examples, Rx represents a hydrogen atom or a methyl group, and Rxa to Rxc each independently represents an alkyl group having 1 to 4 carbon atoms.

  The resin of component (C) preferably has no elements other than carbon atoms, hydrogen atoms, oxygen atoms, nitrogen atoms and sulfur atoms.

Furthermore, the resin (C) may contain at least one group selected from the following groups (x) to (z).
(X) an alkali-soluble group,
(Y) a group that decomposes by the action of an alkali developer and increases the solubility in the alkali developer;
(Z) a group decomposable by the action of an acid

(X) Alkali-soluble groups include phenolic hydroxyl groups, carboxylic acid groups, sulfonic acid groups, sulfonamido groups, sulfonylimide groups, (alkylsulfonyl) (alkylcarbonyl) methylene groups, (alkylsulfonyl) (alkylcarbonyl) imide groups Bis (alkylcarbonyl) methylene group, bis (alkylcarbonyl) imide group, bis (alkylsulfonyl) methylene group, bis (alkylsulfonyl) imide group, tris (alkylcarbonyl) methylene group, tris (alkylsulfonyl) methylene group Groups and the like.
Preferable alkali-soluble groups include a sulfonimide group and a bis (carbonyl) methylene group.

Examples of the repeating unit having an alkali-soluble group (x) include a repeating unit in which an alkali-soluble group is directly bonded to the main chain of the resin, such as a repeating unit of acrylic acid or methacrylic acid, or a main group of the resin via a linking group. It is preferable to use a repeating unit in which an alkali-soluble group is bonded to the chain, and further introduce a polymerization initiator or chain transfer agent having an alkali-soluble group at the end of the polymer chain at the time of polymerization.
The content of the repeating unit having an alkali-soluble group (x) is preferably from 0 to 20 mol%, more preferably from 0 to 10 mol%, based on all repeating units in the polymer.

  Specific examples of the repeating unit having an alkali-soluble group (x) are shown below. Rx represents a hydrogen atom or a methyl group.

(Y) Examples of the group that decomposes by the action of an alkali developer and increases the solubility in the alkali developer include a group having a lactone structure, an acid anhydride, an acid imide group, and the like, and preferably a lactone structure It is group which has.
The repeating unit having a group (y) that is decomposed by the action of an alkali developer and increases the solubility in the alkali developer includes a resin via a linking group such as a repeating unit of an acrylate ester or a methacrylate ester. A polymerization initiator or chain transfer agent having a repeating unit in which an alkali-soluble group is bonded to the main chain or a group (y) that increases solubility in an alkaline developer is introduced at the end of the polymer chain during polymerization. Both are preferable.
The content of the repeating unit having a group (y) whose solubility in an alkali developer increases is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, based on all repeating units in the polymer.

  Specific examples of the repeating unit having a group (y) that increases the solubility in an alkali developer are shown below. Rx represents a hydrogen atom or a methyl group.

  (Z) Examples of the group capable of decomposing by the action of an acid include the same acid-decomposable groups as mentioned for the resin (A). The content of the repeating unit having a group (z) that decomposes by the action of an acid is preferably 0 to 100 mol%, more preferably 0 to 80 mol%, still more preferably 0 to 50 mol%, based on all repeating units in the polymer. It is.

The content of the resin (C) is preferably 0.1 to 20% by mass, more preferably 0.1 to 20% by mass, based on the solid content of the positive resist composition (total solid content constituting the resist film). It is 10 mass%, More preferably, it is 0.1-5 mass%.
Resin (C) is a resin having a molecular weight dispersity (Mw / Mn) of 1.3 or less and a weight average molecular weight (Mw) of 1.0 × 10 ⁴ or less. More preferably, it is a resin having a dispersity of 1.3 or less and a weight average molecular weight of 0.8 × 10 ⁴ or less, more preferably a dispersity of 1.3 or less and a weight average molecular weight of 0. It is a resin that is 7 × 10 ⁴ or less. Most preferred is a resin having a dispersity of 1.25 or less and a weight average molecular weight of 0.6 × 10 ⁴ or less and 0.2 × 10 ⁴ or more. Here, the weight average molecular weight is defined by a polystyrene conversion value of gel permeation chromatography.
As described above, the resin whose dispersion degree and molecular weight are controlled can be a commercially available resin, for example, synthesis of a resin using a living radical polymerization initiator, or purification by solvent fractionation. It can also be made by removing low molecular weight components.

In the present invention, the GPC measurement value is a measurement value under the following conditions.
Apparatus: HLC-8220GPC (manufactured by Tosoh Corporation)
Detector: Differential refractometer (RI detector)
Precolumn: TSKGUARDCOLUMN HXL-L 6mm x 40mm (manufactured by Tosoh Corporation)
Sample side column: The following four columns are directly connected in order (all manufactured by Tosoh Corporation)
・ TSK-GEL GMHXL 7.8mm x 300mm
・ TSK-GEL G4000HXL 7.8mm x 300mm
・ TSK-GEL G3000HXL 7.8mm x 300mm
・ TSK-GEL G2000HXL 7.8mm x 300mm
Reference side column: Same as sample side column Temperature chamber temperature: 40 ° C
Moving bed: THF
Sample-side moving bed flow rate: 1.0 mL / min Reference-side moving bed flow rate: 0.3 mL / min Sample concentration: 0.1% by weight
Sample injection volume: 107 μL
Data collection time: 16 minutes to 46 minutes after sample injection Sampling pitch: 300 msec

  The resin (C) preferably has a residual monomer amount of 0 to 10% by mass, more preferably 0 to 5% by mass, and still more preferably 0 to 1% by mass.

  Resin (C), like acid-decomposable resin (A), naturally has few impurities such as metals, but residual monomers and oligomer components are not more than predetermined values, for example, 0.1% by mass by HPLC. It is preferable that not only the sensitivity, resolution, process stability, pattern shape and the like as a resist can be further improved, but also a resist having no change over time such as foreign matter in liquid or sensitivity can be obtained.

  As the resin (C), various commercially available products can be used, or they can be synthesized according to a conventional method (for example, radical polymerization). For example, as a general synthesis method, a monomer polymerization method in which a monomer species and an initiator are dissolved in a solvent and the polymerization is performed by heating, and a solution of the monomer species and the initiator is dropped into the heating solvent over 1 to 10 hours. The dropping polymerization method is added, and the dropping polymerization method is preferable. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane, diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, amide solvents such as dimethylformamide and dimethylacetamide, Furthermore, the solvent which melt | dissolves the composition of this invention like the below-mentioned propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone is mentioned. More preferably, the polymerization is performed using the same solvent as that used in the resist composition of the present invention. Thereby, the generation of particles during storage can be suppressed.

  The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. As a polymerization initiator, a commercially available radical initiator (azo initiator, peroxide, etc.) is used to initiate the polymerization. As the radical initiator, an azo initiator is preferable, and an azo initiator having an ester group, a cyano group, or a carboxyl group is preferable. Preferred examples of the initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile, dimethyl 2,2′-azobis (2-methylpropionate) and the like. The concentration of the reaction is 5 to 50% by mass, preferably 30 to 50% by mass. The reaction temperature is usually 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, more preferably 60-100 ° C.

  Next, the obtained resin is purified. Purification can be accomplished by a liquid-liquid extraction method that removes residual monomers and oligomer components by combining water and an appropriate solvent, and a purification method in a solution state such as ultrafiltration that extracts and removes only those having a specific molecular weight or less. , Reprecipitation method that removes residual monomer by coagulating resin in poor solvent by dripping resin solution into poor solvent and purification in solid state such as washing filtered resin slurry with poor solvent A normal method such as a method can be applied.

The resin (C) in the present application has a low degree of dispersion as described above. However, such a resin can be a commercially available resin, for example, a resin can be synthesized using a living radical polymerization initiator. It can also be made by removing low molecular weight components using purification by solvent fractionation.
First, purification by solvent fractionation will be described. Purification by solvent fractionation is performed in a solution state such as washing with water or a liquid-liquid extraction method that removes residual monomers and oligomer components by combining appropriate solvents, or ultrafiltration that extracts and removes only those with a specific molecular weight or less. Solid methods such as reprecipitation method for removing residual monomers by coagulating the resin in the poor solvent by dripping the resin solution into the poor solvent and washing the filtered resin slurry with the poor solvent A normal method such as a purification method in a state can be applied. For example, after completion of the radical polymerization reaction, the acid-decomposable resin has a slightly soluble or insoluble solvent (poor solvent) in a volume amount less than 5 times, preferably 4.5 to 0.5 times, more preferably the reaction solution. Is 3 to 0.5 times, more preferably 1 to 0.5 times the volume, and the resin is precipitated as a solid by contact.

  The solvent (precipitation or reprecipitation solvent) used in the precipitation or reprecipitation operation from the polymer solution may be a poor solvent for the polymer. For example, hydrocarbon (pentane, hexane, Aliphatic hydrocarbons such as heptane and octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene), halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride, etc.) Halogenated aliphatic hydrocarbons; halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene), nitro compounds (nitromethane, nitroethane, etc.), nitriles (acetonitrile, benzonitrile, etc.), ethers (diethyl ether, diisopropyl ether, dimethoxyethane) Chain A Cyclic ethers such as tetrahydrofuran and dioxane), ketones (acetone, methyl ethyl ketone, diisobutyl ketone, etc.), esters (ethyl acetate, butyl acetate, etc.), carbonates (dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), alcohols ( (Methanol, ethanol, propanol, isopropyl alcohol, butanol, etc.), carboxylic acids (acetic acid, etc.), mixed solvents containing these solvents, etc. Among these, as the precipitation or reprecipitation solvent, a solvent containing at least a hydrocarbon (particularly, an aliphatic hydrocarbon such as hexane) is preferable. In such a solvent containing at least hydrocarbon, the ratio of hydrocarbon (for example, aliphatic hydrocarbon such as hexane) and other solvent (for example, ester such as ethyl acetate, alcohol such as methanol and ethanol) is For example, the former / the latter (volume ratio; 25 ° C.) = 10/90 to 99/1, preferably the former / the latter (volume ratio; 25 ° C.) = 30/70 to 98/2, more preferably the former / the latter (volume). Ratio: 25 ° C.) = About 50/50 to 97/3.

  The amount of the precipitation or reprecipitation solvent used can be appropriately selected in consideration of efficiency, yield, and the like, but generally 100 to 10000 parts by mass, preferably 200 to 2000 parts by mass with respect to 100 parts by mass of the polymer solution, More preferably, it is 300-1000 mass parts.

  The nozzle diameter at the time of supplying the polymer solution to the precipitation or reprecipitation solvent (poor solvent) is preferably 4 mmφ or less (for example, 0.2 to 4 mmφ). Moreover, the supply speed (dropping speed) of the polymer solution into the poor solvent is, for example, about 0.1 to 10 m / second, preferably about 0.3 to 5 m / second, as the linear speed.

  The precipitation or reprecipitation operation is preferably performed with stirring. As a stirring blade used for stirring, for example, a desk turbine, a fan turbine (including a paddle), a curved blade turbine, an arrow blade turbine, a fiddler type, a bull margin type, an angled blade fan turbine, a propeller, a multistage type, an anchor type (or Horseshoe type), gate type, double ribbon, screw, etc. can be used. Stirring is preferably further performed for 10 minutes or more, particularly 20 minutes or more after the supply of the polymer solution. When the stirring time is short, the monomer content in the polymer particles may not be sufficiently reduced. Further, the polymer solution and the poor solvent can be mixed and stirred using a line mixer instead of the stirring blade.

  The temperature for precipitation or reprecipitation can be appropriately selected in consideration of efficiency and operability, but is usually about 0 to 50 ° C., preferably around room temperature (for example, about 20 to 35 ° C.). The precipitation or reprecipitation operation can be performed by a known method such as a batch method or a continuous method using a conventional mixing vessel such as a stirring tank.

  The precipitated or re-precipitated particulate polymer is usually subjected to conventional solid-liquid separation such as filtration and centrifugation, and dried before use. Filtration is performed using a solvent-resistant filter medium, preferably under pressure. Drying is performed at a temperature of about 30 to 100 ° C., preferably about 30 to 50 ° C. under normal pressure or reduced pressure (preferably under reduced pressure).

The resin may be once deposited and separated, and then dissolved again in a solvent, and the resin may be brought into contact with a hardly soluble or insoluble solvent.
That is, after completion of the radical polymerization reaction, the acid-decomposable resin is brought into contact with a slightly soluble or insoluble solvent to precipitate the resin (step a), the resin is separated from the solution (step b), and dissolved again in the solvent. Resin solution A is prepared (step c), and then a solvent in which the resin is hardly soluble or insoluble is added to the resin solution A in a volume amount less than 5 times that of the resin solution A (preferably 3 times or less). Alternatively, a method including depositing a resin solid by contacting (step d) and separating the deposited resin (step e) may be used.
The solvent used in the preparation of the resin solution A can be the same solvent as the solvent that dissolves the monomer in the polymerization reaction, and may be the same as or different from the solvent used in the polymerization reaction.

Next, living radical polymerization will be described.
Living radical polymerization using a living radical polymerization initiator is a radical polymerization that maintains the activity of the polymerization terminal without losing the activity, and is a pseudo-polymer in which the terminal inactivated and the activated one are in an equilibrium state. Living polymerization is also included. Examples of living radical polymerization include those using chain transfer agents such as polysulfides, those using radical scavengers such as cobalt porphyrin complexes (J. Am. Chem. Soc. 1994, 116, 7943) and nitroxide compounds (Macromolecules, 1994, 27, 7228), atom transfer radical polymerization using organic halides as initiators and transition metal complexes as catalysts (JP 2002-145972, JP 2002-80523, JP 2001-261733, JP 2000-264914). ), And those having RCSS at the growth end (WO9801478A1, WO9858974A1, WO9935177A1, WO9931144, US6380335B1) and the like.

Among living radical polymerizations for producing acid-decomposable group-containing resins, first, a method using a radical scavenger in a nitroxide compound of a living radical polymerization initiator in an example using a thermal radical generator and a nitroxide compound as an initiator Will be described. In this polymerization, a stable nitroxy free radical (= N—O.) Is generally used as a radical capping agent. Examples of such compounds include, but are not limited to, 2,2,6,6-substituted-1-piperidinyloxy radical, 2,2,5,5-substituted-1-pyrrolidinyloxy radical, and the like. Nitroxy free radicals from cyclic hydroxyamines are preferred. As the substituent, an alkyl group having 4 or less carbon atoms such as a methyl group or an ethyl group is suitable.
Specific nitroxy free radical compounds include, but are not limited to, 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO), 2,2,6,6-tetraethyl-1- Piperidinyloxy radical, 2,2,6,6-tetramethyl-4-oxo-1-piperidinyloxy radical, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy radical, 1, Examples include 1,3,3-tetramethyl-2-isoindolinyloxy radical, N, N-di-t-butylamineoxy radical, and the like. Instead of the nitroxy free radical, a stable free radical such as a galvinoxyl free radical may be used.

The radical capping agent is used in combination with a thermal radical generator. It is considered that the reaction product of the radical capping agent and the thermal radical generator serves as a polymerization initiator and the polymerization of the addition polymerizable monomer proceeds. The combination ratio of the both is not particularly limited, but 0.1 to 10 mol of the thermal radical generator is suitable for 1 mol of the radical capping agent.
As the thermal radical generator, various compounds can be used, but peroxides and azo compounds capable of generating radicals under polymerization temperature conditions are preferred. Examples of the peroxide include, but are not limited to, diacyl peroxides such as benzoyl peroxide and lauroyl peroxide; dialkyl peroxides such as dicumyl peroxide and di-t-butyl peroxide; diisopropyl peroxydicarbonate, bis Peroxycarbonates such as (4-t-butylcyclohexyl) peroxydicarbonate; alkyl peresters such as t-butylperoxyoctate and t-butylperoxybenzoate. Benzoyl peroxide is particularly preferable. As the azo compound, 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis- (4-methoxy-2,4- Dimethyl valeronitrile), dimethyl azobisisobutyrate, and the like, and dimethyl azobisisobutyrate and 2,2′-azobisisobutyronitrile are particularly preferable.

  Further, as reported in Macromolecules, 1995, Vol. 28, p. 2993, instead of an example using a thermal radical generator and a radical capping agent, the formulas (9) and (10) are used. Can be used as initiators.

When an alkoxyamine compound is used as an initiator, if it has a functional group such as a hydroxyl group as shown in Formula (10), a polymer having a functional group at the terminal can be obtained.
Polymerization conditions such as a monomer, a solvent, and a polymerization temperature used in polymerization using a radical scavenger such as the above nitroxide compound are not limited, but may be the same as those used for atom transfer radical polymerization described below.

As the living radical polymerization initiator, a polymerization initiator composed of a transition metal complex, an organic halogen compound, and a Lewis acid or an amine can be used.
As the central metal constituting the transition metal complex, Group 7 to 11 elements of the periodic table such as iron, copper, nickel, rhodium, ruthenium, rhenium (Chemical Handbook Basic Edition I revised 4th edition) 1993)) is preferred. Of these, ruthenium and copper are preferred.
Specific examples of the transition metal complex having ruthenium as a central metal include dichlorotris (triphenylphosphine) ruthenium, dichlorotris (tributylphosphine) ruthenium, dichloro (cyclooctadiene) ruthenium, dichlorobenzeneruthenium, dichloro p-cymeneruthenium, Dichloro (norbornadiene) ruthenium, cis-dichlorobis (2,2′-bipyridine) ruthenium, dichlorotris (1,10-phenanthroline) ruthenium, carbonylchlorohydridotris (triphenylphosphine) ruthenium, chlorocyclopentadienylbis (triphenyl) Phosphine) ruthenium, chloropentamethylcyclopentadienylbis (triphenylphosphine) ruthenium, chloroindenylbis (triphenylphosphine) ) Ruthenium and the like, and particularly preferred is dichlorotris (triphenylphosphine) ruthenium, chloropentamethylcyclopentadienylbis (triphenylphosphine) ruthenium or chloroindenylbis (triphenylphosphine) ruthenium.

  The organic halogen compound functions as a polymerization initiator. As such an organic halogen compound, an α-halogenocarbonyl compound or an α-halogenocarboxylic acid ester can be used, and among them, an α-halogenocarboxylic acid ester is preferable, and specific examples thereof include ethyl 2-bromo-2-methylpropanoate, Examples include 2-hydroxyethyl 2-bromopropionate and dimethyl 2-chloro-2,4,4-trimethylglutarate.

The Lewis acid or amine functions as an activator. Examples of such Lewis acids include aluminum trialkoxides such as aluminum triisopropoxide and aluminum tri (t-butoxide); bis (2,6-di-t-butylphenoxy) methylaluminum, bis (2,4,4). Bis (substituted aryloxy) alkylaluminum such as 6-tri-t-butylphenoxy) methylaluminum; Tris (substituted aryloxy) aluminum such as tris (2,6-diphenylphenoxy) aluminum; Titanium such as titanium tetraisopropoxide Examples include tetraalkoxides, preferably aluminum trialkoxides, and particularly preferably aluminum triisopropoxides.
Examples of amines include aliphatic primary amines such as methylamine, ethylamine, propylamine, isopropylamine, and butylamine, aliphatic secondary amines such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, and dibutylamine, and trimethylamine. Aliphatic amines such as aliphatic tertiary amines such as triethylamine, tripropylamine, triisopropylamine, tributylamine; N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ′ Aliphatic polyamines such as', N ″ -pentamethyldiethylenetriamine and 1,1,4,7,10,10-hexamethyltriethylenetetraamine; aromatic primary amines such as aniline and toluidine, and fragrances such as diphenylamine Secondary amines such as triphenylamine Aromatic amines such as any aromatic tertiary amine can be mentioned. Of these, aliphatic amines are preferable, and butylamine, dibutylamine, tributylamine and the like are particularly preferable.

The content ratio of each component in the polymerization initiator system comprising a transition metal complex and an organic halogen compound, and a Lewis acid or amine is not necessarily limited, but if the ratio of the transition metal complex to the organic halogen compound is too low Polymerization tends to be slow, and conversely, if it is too high, the molecular weight distribution of the resulting polymer tends to be broad, so the molar ratio of transition metal complex: organic halogen compound is 0.05: 1 to 1: 1. A range is preferable. In addition, if the ratio of Lewis acid or amine to the transition metal complex is too low, the polymerization is slow, and conversely, if it is too high, the molecular weight distribution of the resulting polymer tends to be widened, so the organic halogen compound: Lewis acid or amine Is preferably in the range of 1: 1 to 1:10.
The living radical polymerization initiator system can be usually prepared by mixing a transition metal complex, an organic halogen compound polymerization initiator, and a Lewis acid or amine activator in a conventional manner immediately before use. In addition, the transition metal complex, the polymerization initiator, and the activator are stored separately, added separately to the polymerization reaction system, and mixed in the polymerization reaction system to function as a living radical polymerization initiator system. You may do it.
Other living radical polymerization initiators include compounds represented by formula (8).

In the formula (8), R ′ represents an alkyl group having 1 to 15 carbon atoms or an aryl group which may contain an ester group, an ether group, an amino group, an amide group, etc., and Y represents a single bond, an oxygen atom, nitrogen Represents an atom or a sulfur atom, and R ″ represents an alkyl group having 1 to 15 carbon atoms or an aryl group which may contain an ester group, an ether group, an amino group, or the like.
Specific examples of R ′, particularly preferred when Y is a single bond, include methyl group, ethyl group, propyl group, butyl group, cyclohexyl group, norbornyl group, dinorbornyl group, adamantyl group, phenyl group, benzyl group, hydroxymethyl Group, hydroxyethyl group, hydroxycyclohexyl group and the like.
Specific examples of those particularly preferable when Y is an oxygen atom include methyl, ethyl, propyl, butyl, cyclohexyl, norbornyl, dinorbornyl, adamantyl, phenyl, benzyl, hydroxymethyl, hydroxyethyl. Group, hydroxycyclohexyl group and the like.
When Y is a nitrogen atom, R′—Y— in the above formula (8) is (R ′) (R ′) N—, but as a specific example of particularly preferred R ′ at that time, independently Methyl, ethyl, propyl, butyl, cyclohexyl, norbornyl, dinorbornyl, adamantyl, phenyl, benzyl, hydroxymethyl, hydroxyethyl, hydroxycyclohexyl, piperidinyl, dimethylamino, diethylamino Group, acetamide group and the like. R ′ may form a ring, and in this case, groups represented by formula (8-1) to formula (8-3) are exemplified.

Specific examples of those particularly preferable when Y is a sulfur atom include methyl, ethyl, propyl, butyl, cyclohexyl, norbornyl, dinorbornyl, adamantyl, phenyl, benzyl, hydroxymethyl, hydroxyethyl. Group, hydroxycyclohexyl group and the like.
Specific examples of particularly preferable R ″ include groups represented by formulas (8-4) to (8-8).

  The polymerization initiator can be used in combination with heat or a photo radical generator. Specific examples of the thermal radical generator include 2,2-azobis (isobutyronitrile), 2,2′-azobis (2-cyano-2-butane), dimethyl 2,2′-azobisdimethylisobutyrate 4,4′-azobis (4-cyanopentanoic acid), 1,1′-azobis (cyclohexanecarbonitrile), 2- (t-butylazo) -2-cyanopropane, 2,2′-azobis [2-methyl -N- (1,1) -bis (hydroxymethyl) -2-hydroxyethyl] propionamide, 2,2'-azobis [2-methyl-N-hydroxyethyl]]-propionamide, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) dihydrochloride, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N ' Dimethyleneisobutylamine), 2,2′-azobis (2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide), 2,2′-azobis (2-methyl-) N- [1,1-bis (hydroxymethyl) ethyl] propionamide, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2-azobis (isobutylamide) dihydrate ), 2,2′-azobis (2,2,4-trimethylpentane), 2,2′-azobis (2-methylpropane), t-butylperoxyacetate, t-butylperoxybenzoate, t-butylperoxy Octoate, t-butylperoxyneodecanoate, t-butylperoxyisobutyrate, t-amylperoxypi Rato, t-butyl peroxypivalate, di-isopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, dicumyl peroxide, dibenzoyl peroxide, dilauroyl peroxide, potassium peroxydisulfate, ammonium peroxydisulfate, di-t-hypochlorous acid Examples include butyl nitrate and dicumyl hyponitrite.

Examples of the solvent used in the living radical polymerization include cycloalkanes such as cyclohexane and cycloheptane; saturated carboxylic acids such as ethyl acetate, n-butyl acetate, i-butyl acetate, methyl propionate, and propylene glycol monomethyl ether acetate. Esters; alkyl lactones such as γ-butyrolactone; airs such as tetrahydrofuran, dimethoxyethanes and diethoxyethanes; alkyl ketones such as 2-butanone, 2-heptanone and methyl isobutyl ketone; cycloalkyl ketones such as cyclohexanone Alcohols such as 2-propanol and propylene glycol monomethyl ether; aromatics such as toluene, xylene and chlorobenzene; dimethylformamide, dimethyl sulfoxide, dimethylacetamide , It may be mentioned aprotic polar solvent or without a solvent, such as N- methyl-2-pyrrolidone.
These solvents can be used alone or in admixture of two or more.
Moreover, the reaction temperature in the said superposition | polymerization is 40-150 degreeC normally, Preferably it is 50-130 degreeC, and reaction time is 1 to 96 hours normally, Preferably it is 1 to 48 hours.

The resin (C) according to the present invention is preferably a polymer polymerized randomly without repeating each repeating unit constituting the resin.
As a means for randomly polymerizing the monomers constituting each repeating unit, the monomers forming the repeating units represented by the above formulas (1) to (7) may be added together or mixed. Then, it is obtained by polymerization.
Naturally, the obtained resin (C) has few impurities such as halogen and metal, and the residual monomer and oligomer components are preferably not more than predetermined values, for example, 0.1% by mass or the like by HPLC. As a result, not only can the sensitivity, resolution, process stability, pattern shape, and the like as a resist be further improved, but also a resist having no change over time such as foreign matter in liquid or sensitivity can be obtained.

The resin (C) obtained by the living radical polymerization method may have an initiator-derived residue at the end of the molecular chain. Although this residue may be present, this residue can be further removed using an excess radical polymerization initiator. The end treatment can be performed on the end product of the polymerization reaction after completion of the living radical polymerization reaction, or the polymer end treatment can be performed after the once produced polymer is purified.
Usable radical polymerization initiators can be used as long as radicals can be generated under the conditions of molecular chain end group treatment. Radical generation conditions include high energy radiation such as heat, light, gamma rays or electron beams.
Specific examples of the radical polymerization initiator include initiators such as peroxides and azo compounds. Although not particularly limited, specific radical polymerization initiators include t-butyl hydroperoxide, t-butyl perbenzoate, benzoyl peroxide, 2,2′-azobis (2,4-dimethylvaleronitrile), 2, Examples include 2'-azobisisobutyronitrile (AIBN), 1,1'-azobis (cyclohexanecarbonitrile), dimethyl-2,2'-azobisisobutyrate (MAIB), benzoin ether, benzophenone, and the like.
When a thermal radical polymerization initiator is used, the temperature of the resin end group treatment reaction is about 20 to 200 ° C, preferably 40 to 150 ° C, more preferably 50 to 100 ° C. The reaction atmosphere is an inert atmosphere such as nitrogen or argon, or an air atmosphere. The pressure of the reaction can be normal pressure or increased pressure. The amount of the radical polymerization initiator is 1 to 800% mol, preferably 50 to 400% mol of the total number of moles of residues present in the polymer to be end-treated as the amount of radical generated by the radical polymerization initiator. Preferably, it can introduce | transduce so that it may become 100-300% mol, More preferably, it is 200-300% mol.
The reaction time for the terminal treatment is 0.5 to 72 hours, preferably 1 to 24 hours, more preferably 2 to 12 hours. Removal of residues such as thiogroups from the polymer ends is at least 50%, preferably at least 75%, more preferably 85%, even more preferably 95%. The end-treated polymer is replaced at the end with new radical species, such as radical initiator fragments derived from the radical initiator used in the end-treatment reaction. The resulting polymer has a new group at the end and can be used according to the application.
In addition, the polymer terminal treatment can remove the residue derived from the polymerization initiator also by the method described in WO 02/090397.

In this invention, resin (C) can be used individually or in mixture of 2 or more types.
Specific examples of the resin are shown below. The following table shows the molar ratio of repeating units in each resin (corresponding to each repeating unit in order from the left), the weight average molecular weight, and the degree of dispersion.

In order to prevent the resist film from coming into direct contact with the immersion liquid between the resist film made of the resist composition of the present invention and the immersion liquid, an immersion liquid hardly soluble film (hereinafter also referred to as “top coat”) is provided. It may be provided. The functions necessary for the top coat are suitability for application to the upper layer of the resist, transparency to radiation, particularly 193 nm, and poor immersion liquid solubility. It is preferable that the top coat is not mixed with the resist and can be uniformly applied to the resist upper layer.
From the viewpoint of 193 nm transparency, the top coat is preferably a polymer that does not contain abundant aromatics. Specifically, the polymer contains a hydrocarbon polymer, an acrylate polymer, polymethacrylic acid, polyacrylic acid, polyvinyl ether, and silicon. Examples thereof include a polymer and a fluorine-containing polymer. The above-mentioned hydrophobic resin (C) is also suitable as a top coat. From the viewpoint of contaminating the optical lens when impurities are eluted from the top coat into the immersion liquid, it is preferable that the residual monomer component of the polymer contained in the top coat is small.

When peeling the top coat, a developer may be used, or a separate release agent may be used. As the release agent, a solvent having a small penetration into the resist film is preferable. It is preferable that the peeling process can be performed with an alkali developer in that the peeling process can be performed simultaneously with the resist film development process. From the viewpoint of peeling with an alkaline developer, the topcoat is preferably acidic, but may be neutral or alkaline from the viewpoint of non-intermixability with the resist film.
The resolution is improved when there is no difference in refractive index between the top coat and the immersion liquid. In the case of using water as the immersion liquid in an ArF excimer laser (wavelength: 193 nm), the top coat for ArF immersion exposure is preferably close to the refractive index of the immersion liquid. From the viewpoint of making the refractive index close to the immersion liquid, it is preferable to have fluorine atoms in the topcoat. A thin film is more preferable from the viewpoint of transparency and refractive index.

The top coat is preferably not mixed with the resist film and further not mixed with the immersion liquid. From this point of view, when the immersion liquid is water, the solvent used for the top coat is preferably a water-insoluble medium that is hardly soluble in the solvent used for the resist composition. Furthermore, when the immersion liquid is an organic solvent, the topcoat may be water-soluble or water-insoluble.
Further, the hydrophobic resin (C) can be suitably used as a top coat.

(D) Solvent Examples of the solvent that can be used in preparing the positive resist composition by dissolving the above components include, for example, alkylene glycol monoalkyl ether carboxylate, alkylene glycol monoalkyl ether, alkyl lactate ester, Examples thereof include organic solvents such as alkyl alkoxypropionates, cyclic lactones having 4 to 10 carbon atoms, monoketone compounds having 4 to 10 carbon atoms, which may contain a ring, alkylene carbonate, alkyl alkoxyacetates, and alkyl pyruvates. .

Examples of the alkylene glycol monoalkyl ether carboxylate include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl Preferred examples include ether propionate, ethylene glycol monomethyl ether acetate, and ethylene glycol monoethyl ether acetate.
Preferred examples of the alkylene glycol monoalkyl ether include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether.

Preferred examples of the alkyl lactate include methyl lactate, ethyl lactate, propyl lactate and butyl lactate.
Preferable examples of the alkyl alkoxypropionate include ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, methyl 3-ethoxypropionate, and ethyl 3-methoxypropionate.

  Examples of the cyclic lactone having 4 to 10 carbon atoms include β-propiolactone, β-butyrolactone, γ-butyrolactone, α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone, γ- Caprolactone, γ-octanoic lactone, and α-hydroxy-γ-butyrolactone are preferred.

  Examples of the monoketone compound having 4 to 10 carbon atoms which may contain a ring include 2-butanone, 3-methylbutanone, pinacolone, 2-pentanone, 3-pentanone, 3-methyl-2-pentanone, 4- Methyl-2-pentanone, 2-methyl-3-pentanone, 4,4-dimethyl-2-pentanone, 2,4-dimethyl-3-pentanone, 2,2,4,4-tetramethyl-3-pentanone, 2 -Hexanone, 3-hexanone, 5-methyl-3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-methyl-3-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4 -Heptanone, 2-octanone, 3-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone, 3-decanone, 4-decanone, 5- Xen-2-one, 3-penten-2-one, cyclopentanone, 2-methylcyclopentanone, 3-methylcyclopentanone, 2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopenta Non, cyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 4-ethylcyclohexanone, 2,2-dimethylcyclohexanone, 2,6-dimethylcyclohexanone, 2,2,6-trimethylcyclohexanone, cycloheptanone, 2-methylcyclo Preferred are heptanone and 3-methylcycloheptanone.

Preferred examples of the alkylene carbonate include propylene carbonate, vinylene carbonate, ethylene carbonate, and butylene carbonate.
Examples of the alkyl alkoxyacetate include 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2- (2-ethoxyethoxy) ethyl acetate, 3-methoxy-3-methylbutyl acetate, and 1-methoxy-acetate. 2-propyl is preferred.
Preferred examples of the alkyl pyruvate include methyl pyruvate, ethyl pyruvate, and propyl pyruvate.
As a solvent which can be preferably used, a solvent having a boiling point of 130 ° C. or higher under normal temperature and normal pressure can be mentioned. Specifically, cyclopentanone, γ-butyrolactone, cyclohexanone, ethyl lactate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, ethyl 3-ethoxypropionate, ethyl pyruvate, 2-ethoxyethyl acetate, acetic acid -2- (2-ethoxyethoxy) ethyl and propylene carbonate are mentioned.
In the present invention, the above solvents may be used alone or in combination of two or more.

In this invention, you may use the mixed solvent which mixed the solvent which contains a hydroxyl group in a structure, and the solvent which does not contain a hydroxyl group as an organic solvent.
Examples of the solvent containing a hydroxyl group include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethyl lactate, and the like. Particularly preferred are propylene glycol monomethyl ether and ethyl lactate.
Examples of the solvent not containing a hydroxyl group include propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, 2-heptanone, γ-butyrolactone, cyclohexanone, butyl acetate, N-methylpyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide and the like. Among these, propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, 2-heptanone, γ-butyrolactone, cyclohexanone, and butyl acetate are particularly preferred, and propylene glycol monomethyl ether acetate, ethyl ethoxypropionate. 2-heptanone is most preferred.
The mixing ratio (mass) of the solvent containing a hydroxyl group and the solvent not containing a hydroxyl group is 1/99 to 99/1, preferably 10/90 to 90/10, more preferably 20/80 to 60/40. . A mixed solvent containing 50% by mass or more of a solvent not containing a hydroxyl group is particularly preferred from the viewpoint of coating uniformity.

  The solvent is preferably a mixed solvent of two or more containing propylene glycol monomethyl ether acetate.

(E) Basic compound The positive resist composition of the present invention preferably contains (E) a basic compound in order to reduce a change in performance over time from exposure to heating.
Preferred examples of the basic compound include compounds having structures represented by the following formulas (A) to (E).

In general formulas (A) and (E),
R ²⁰⁰ , R ²⁰¹ and R ²⁰² may be the same or different, and are a hydrogen atom, an alkyl group (preferably having 1 to 20 carbon atoms), a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group (having a carbon number). 6-20), wherein R ²⁰¹ and R ²⁰² may combine with each other to form a ring.

About the said alkyl group, as an alkyl group which has a substituent, a C1-C20 aminoalkyl group, a C1-C20 hydroxyalkyl group, or a C1-C20 cyanoalkyl group is preferable.
R ²⁰³ , R ²⁰⁴ , R ²⁰⁵ and R ²⁰⁶ may be the same or different and each represents an alkyl group having 1 to 20 carbon atoms.
The alkyl groups in these general formulas (A) to (E) are more preferably unsubstituted.

  Preferred compounds include guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, piperidine and the like, and more preferred compounds include imidazole structure, diazabicyclo structure, onium hydroxide structure, onium carboxylate Examples thereof include a compound having a structure, a trialkylamine structure, an aniline structure or a pyridine structure, an alkylamine derivative having a hydroxyl group and / or an ether bond, and an aniline derivative having a hydroxyl group and / or an ether bond.

Examples of the compound having an imidazole structure include imidazole, 2,4,5-triphenylimidazole, and benzimidazole. Examples of the compound having a diazabicyclo structure include 1,4-diazabicyclo [2,2,2] octane, 1,5-diazabicyclo [4,3,0] non-5-ene, and 1,8-diazabicyclo [5,4,0. ] Undecar 7-ene etc. are mentioned. Examples of the compound having an onium hydroxide structure include triarylsulfonium hydroxide, phenacylsulfonium hydroxide, sulfonium hydroxide having a 2-oxoalkyl group, specifically triphenylsulfonium hydroxide, tris (t-butylphenyl) sulfonium. Examples thereof include hydroxide, bis (t-butylphenyl) iodonium hydroxide, phenacylthiophenium hydroxide, and 2-oxopropylthiophenium hydroxide. As the compound having an onium carboxylate structure, an anion portion of the compound having an onium hydroxide structure is converted to a carboxylate, and examples thereof include acetate, adamantane-1-carboxylate, and perfluoroalkylcarboxylate. Examples of the compound having a trialkylamine structure include tri (n-butyl) amine and tri (n-octyl) amine. Examples of the aniline compound include 2,6-diisopropylaniline, N, N-dimethylaniline, N, N-dibutylaniline, N, N-dihexylaniline and the like. Examples of the alkylamine derivative having a hydroxyl group and / or an ether bond include ethanolamine, diethanolamine, triethanolamine, and tris (methoxyethoxyethyl) amine. Examples of aniline derivatives having a hydroxyl group and / or an ether bond include N, N-bis (hydroxyethyl) aniline.
These basic compounds are used alone or in combination of two or more.

  The usage-amount of a basic compound is 0.001-10 mass% normally on the basis of solid content of a positive resist composition, Preferably it is 0.01-5 mass%.

  The use ratio of the acid generator and the basic compound in the composition is preferably acid generator / basic compound (molar ratio) = 2.5 to 300. In other words, the molar ratio is preferably 2.5 or more from the viewpoint of sensitivity and resolution, and is preferably 300 or less from the viewpoint of suppressing the reduction in resolution due to the thickening of the resist pattern over time until post-exposure heat treatment. The acid generator / basic compound (molar ratio) is more preferably 5.0 to 200, still more preferably 7.0 to 150.

(F) Surfactant The positive resist composition of the present invention preferably further contains (F) a surfactant, and is a fluorine-based and / or silicon-based surfactant (fluorine-based surfactant, silicon-based interface). It is more preferable to contain any one or two or more of an activator and a surfactant having both a fluorine atom and a silicon atom.

When the positive resist composition of the present invention contains the surfactant (F), a resist having good sensitivity and resolution and less adhesion and development defects when using an exposure light source of 250 nm or less, particularly 220 nm or less. A pattern can be given.
Examples of the fluorine-based and / or silicon-based surfactant include, for example, JP-A No. 62-36663, JP-A No. 61-226746, JP-A No. 61-226745, JP-A No. 62-170950, JP 63-34540 A, JP 7-230165 A, JP 8-62834 A, JP 9-54432 A, JP 9-5988 A, JP 2002-277862 A, US Patent Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511, 5,824,451 Surfactant can be mentioned, The following commercially available surfactant can also be used as it is.
Examples of commercially available surfactants that can be used include F-top EF301, EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430, 431, 4430 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173, F176, F189 , F113, F110, F177, F120, R08 (Dainippon Ink Chemical Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), Troisol S-366 (Manufactured by Troy Chemical Co., Ltd.), GF-300, GF-150 (manufactured by Toagosei Chemical Co., Ltd.), Surflon S-393 (manufactured by Seimi Chemical Co., Ltd.), F-top EF121, EF122A, EF122B, RF122C, EF125M , EF135M, EF351, 352, EF801, EF802, EF 01 (manufactured by Gemco), PF636, PF656, PF6320, PF6520 (manufactured by OMNOVA), FTX-204D, 208G, 218G, 230G, 204D, 208D, 212D, 218, 222D (manufactured by Neos) Fluorine type surfactant or silicon type surfactant can be mentioned. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

In addition to the known surfactants described above, the surfactant is derived from a fluoroaliphatic compound produced by a telomerization method (also called telomer method) or an oligomerization method (also called oligomer method). A surfactant using a polymer having a fluoroaliphatic group can be used. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.
As the polymer having a fluoroaliphatic group, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate and / or (poly (oxyalkylene)) methacrylate is preferable and distributed irregularly. Or may be block copolymerized. Examples of the poly (oxyalkylene) group include a poly (oxyethylene) group, a poly (oxypropylene) group, a poly (oxybutylene) group, and the like, and a poly (oxyethylene, oxypropylene, and oxyethylene group). A unit having different chain lengths in the same chain length, such as a block link) or poly (block link of oxyethylene and oxypropylene) may be used. Furthermore, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate (or methacrylate) is not only a binary copolymer but also a monomer having two or more different fluoroaliphatic groups, Further, it may be a ternary or higher copolymer obtained by simultaneously copolymerizing two or more different (poly (oxyalkylene)) acrylates (or methacrylates).

Examples of commercially available surfactants include Megafac F178, F-470, F-473, F-475, F-476, and F-472 (Dainippon Ink Chemical Co., Ltd.). Further, a copolymer of an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxyalkylene)) acrylate (or methacrylate), an acrylate (or methacrylate) having a C ₃ F ₇ group and (poly (oxy) And a copolymer of (ethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) acrylate (or methacrylate).

  In the present invention, other surfactants other than fluorine-based and / or silicon-based surfactants can also be used. Specifically, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, polyoxyethylene nonylphenol ether, etc. Sorbitans such as polyoxyethylene alkyl allyl ethers, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate Fatty acid esters, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopal Te - DOO, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, may be mentioned polyoxyethylene sorbitan tristearate nonionic surfactants of polyoxyethylene sorbitan fatty acid esters such as such.

  These surfactants may be used alone or in several combinations.

  (F) The usage-amount of surfactant becomes like this. Preferably it is 0.01-10 mass% with respect to positive resist composition whole quantity (except a solvent), More preferably, it is 0.1-5 mass%.

(G) Carboxylic acid onium salt The positive resist composition in the present invention may contain (G) a carboxylic acid onium salt. Examples of the carboxylic acid onium salt include a carboxylic acid sulfonium salt, a carboxylic acid iodonium salt, and a carboxylic acid ammonium salt. In particular, the (G) carboxylic acid onium salt is preferably an iodonium salt or a sulfonium salt. Furthermore, it is preferable that the carboxylate residue of the (H) carboxylic acid onium salt of the present invention does not contain an aromatic group or a carbon-carbon double bond. As a particularly preferable anion moiety, a linear, branched, monocyclic or polycyclic alkylcarboxylic acid anion having 1 to 30 carbon atoms is preferable. More preferably, an anion of a carboxylic acid in which some or all of these alkyl groups are fluorine-substituted is preferable. The alkyl chain may contain an oxygen atom. This ensures transparency with respect to light of 220 nm or less, improves sensitivity and resolution, and improves density dependency and exposure margin.

  Fluoro-substituted carboxylic acid anions include fluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, pentafluoropropionic acid, heptafluorobutyric acid, nonafluoropentanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorocyclohexanecarboxylic acid, 2 , 2-bistrifluoromethylpropionic acid anion and the like.

  These (G) carboxylic acid onium salts can be synthesized by reacting sulfonium hydroxide, iodonium hydroxide, ammonium hydroxide and carboxylic acid with silver oxide in a suitable solvent.

  The content of the carboxylic acid onium salt in the composition is generally 0.1 to 20% by mass, preferably 0.5 to 10% by mass, and more preferably 1%, based on the total solid content of the composition. -7% by mass.

(H) Other Additives The positive resist composition of the present invention further has solubility in dyes, plasticizers, photosensitizers, light absorbers, alkali-soluble resins, dissolution inhibitors and developers as necessary. (For example, a phenol compound having a molecular weight of 1000 or less, an alicyclic compound having a carboxyl group, or an aliphatic compound) and the like can be contained.

Such phenolic compounds having a molecular weight of 1000 or less can be obtained by referring to, for example, the methods described in JP-A-4-1222938, JP-A-2-28531, US Pat. No. 4,916,210, European Patent 219294, etc. It can be easily synthesized by those skilled in the art.
Specific examples of alicyclic or aliphatic compounds having a carboxyl group include carboxylic acid derivatives having a steroid structure such as cholic acid, deoxycholic acid, lithocholic acid, adamantane carboxylic acid derivatives, adamantane dicarboxylic acid, cyclohexane carboxylic acid, cyclohexane Examples thereof include, but are not limited to, dicarboxylic acids.

(I) Pattern Forming Method The positive resist composition of the present invention is preferably used at a film thickness of 30 to 250 nm, more preferably at a film thickness of 30 to 200 nm, from the viewpoint of improving resolution. preferable. Such a film thickness can be obtained by setting the solid content concentration in the positive resist composition to an appropriate range to give an appropriate viscosity and improving the coating property and film forming property.
The total solid content concentration in the positive resist composition is generally 1 to 10% by mass, more preferably 1 to 8.0% by mass, and still more preferably 1.0 to 6.0% by mass.

  The positive resist composition of the present invention is used by dissolving the above components in a predetermined organic solvent, preferably the mixed solvent, filtering the solution, and then applying the solution on a predetermined support as follows. The filter used for filter filtration is preferably made of polytetrafluoroethylene, polyethylene, or nylon having a pore size of 0.1 microns or less, more preferably 0.05 microns or less, and still more preferably 0.03 microns or less.

For example, a positive resist composition is coated on a substrate (eg, silicon / silicon dioxide coating) used for manufacturing a precision integrated circuit element by an appropriate coating method such as a spinner or a coater, and dried to form a resist film. Form. In addition, you may coat a well-known antireflection film beforehand.
The resist film is irradiated with actinic rays or radiation through a predetermined mask, preferably baked (heated), developed and rinsed. Thereby, a good pattern can be obtained.

Examples of the actinic ray or radiation include infrared light, visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, etc., preferably 250 nm or less, more preferably 220 nm or less, particularly preferably 1 to 1. Far ultraviolet light having a wavelength of 200 nm, specifically, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ excimer laser (157 nm), X-ray, electron beam, etc. ArF excimer laser, F ₂ Excimer laser, EUV (13 nm), and electron beam are preferable.

Before forming the resist film, an antireflection film may be coated on the substrate in advance.
As the antireflection film, any of an inorganic film type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, and amorphous silicon, and an organic film type made of a light absorber and a polymer material can be used. In addition, as the organic antireflection film, commercially available organic antireflection films such as DUV30 series, DUV-40 series manufactured by Brewer Science, AR-2, AR-3, AR-5 manufactured by Shipley, etc. may be used. it can.

In the development step, an alkaline developer is used as follows. As an alkaline developer of the resist composition, inorganic hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, primary amines such as ethylamine and n-propylamine, Secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide and the like Alkaline aqueous solutions such as quaternary ammonium salts, cyclic amines such as pyrrole and pihelidine can be used.
Furthermore, alcohols and surfactants can be added in appropriate amounts to the alkaline developer.
The alkali concentration of the alkali developer is usually from 0.1 to 20% by mass.
The pH of the alkali developer is usually from 10.0 to 15.0.
Furthermore, alcohols and surfactants can be added in appropriate amounts to the alkaline aqueous solution.
As the rinsing liquid, pure water can be used, and an appropriate amount of a surfactant can be added.
Further, after the development process or the rinsing process, a process of removing the developer or the rinsing liquid adhering to the pattern with a supercritical fluid can be performed.

  Exposure (immersion exposure) may be performed by filling a liquid (immersion medium) having a higher refractive index than air between the resist film and the lens during irradiation with actinic rays or radiation. Thereby, resolution can be improved. As the immersion medium to be used, any liquid can be used as long as it has a higher refractive index than air, but pure water is preferred. Further, an overcoat layer may be further provided on the resist film so that the immersion medium and the resist film do not come into direct contact with each other during immersion exposure. Thereby, elution of the composition from the resist film to the immersion medium is suppressed, and development defects are reduced.

The immersion liquid used for the immersion exposure will be described below.
The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient as small as possible so as to minimize distortion of the optical image projected onto the resist. In the case of an ArF excimer laser (wavelength: 193 nm), it is preferable to use water from the viewpoints of availability and ease of handling in addition to the above-described viewpoints.
Further, a medium having a refractive index of 1.5 or more can be used in that the refractive index can be further improved. This medium may be an aqueous solution or an organic solvent.

  When water is used as the immersion liquid, the surface tension of the water is decreased and the surface activity is increased, so that the resist layer on the wafer is not dissolved and the influence on the optical coating on the lower surface of the lens element can be ignored. An additive (liquid) may be added in a small proportion. The additive is preferably an aliphatic alcohol having a refractive index substantially equal to that of water, and specifically includes methyl alcohol, ethyl alcohol, isopropyl alcohol and the like. By adding an alcohol having a refractive index substantially equal to that of water, even if the alcohol component in water evaporates and the content concentration changes, an advantage that the change in the refractive index of the entire liquid can be made extremely small can be obtained. On the other hand, when an opaque substance or impurities whose refractive index is significantly different from that of water are mixed with respect to 193 nm light, the optical image projected on the resist is distorted. Therefore, distilled water is preferable as the water to be used. Further, pure water filtered through an ion exchange filter or the like may be used.

The electrical resistance of water is desirably 18.3 MQcm or more, the TOC (organic substance concentration) is desirably 20 ppb or less, and deaeration treatment is desirably performed.
Moreover, it is possible to improve lithography performance by increasing the refractive index of the immersion liquid. From such a viewpoint, an additive for increasing the refractive index may be added to water, or heavy water (D ₂ O) may be used instead of water.

  When the positive resist composition of the present invention is used as a resist film, the receding contact angle of water with respect to the resist film is preferably 70 ° or more. Here, the receding contact angle is at normal temperature and pressure. The receding contact angle is the receding contact angle when the droplet starts to drop when the resist film is tilted.

Since the resist film is not directly brought into contact with the immersion liquid between the resist film of the positive resist composition of the present invention and the immersion liquid, it is also referred to as an “immersion liquid hardly soluble film” (hereinafter referred to as “top coat”). ) May be provided. The functions necessary for the top coat are suitability for application to the upper layer of the resist, transparency to radiation, particularly 193 nm, and poor immersion liquid solubility. It is preferable that the top coat is not mixed with the resist and can be uniformly applied to the resist upper layer.
From the viewpoint of 193 nm transparency, the topcoat is preferably a polymer that does not contain an aromatic, and specifically, a hydrocarbon polymer, an acrylate polymer, a polymethacrylic acid, a polyacrylic acid, a polyvinyl ether, a silicon-containing polymer, And fluorine-containing polymers. From the viewpoint of contaminating the optical lens when impurities are eluted from the top coat into the immersion liquid, it is preferable that the residual monomer component of the polymer contained in the top coat is small.

When peeling the top coat, a developer may be used, or a separate release agent may be used. As the release agent, a solvent having a small penetration into the resist is preferable. It is preferable that the peeling process can be performed with an alkali developer in that the peeling process can be performed simultaneously with the resist development process. From the viewpoint of peeling with an alkaline developer, the topcoat is preferably acidic, but may be neutral or alkaline from the viewpoint of non-intermixability with the resist.
The resolution is improved when there is no difference in refractive index between the top coat and the immersion liquid. In the case of using water as the immersion liquid in an ArF excimer laser (wavelength: 193 nm), the top coat for ArF immersion exposure is preferably close to the refractive index of the immersion liquid. From the viewpoint of making the refractive index close to the immersion liquid, it is preferable to have fluorine atoms in the topcoat. A thin film is more preferable from the viewpoint of transparency and refractive index.

  It is preferred that the top coat is not mixed with the resist and further not mixed with the immersion liquid. From this viewpoint, when the immersion liquid is water, the topcoat solvent is preferably a resist solvent hardly soluble and water-insoluble medium. Furthermore, when the immersion liquid is an organic solvent, the topcoat may be water-soluble or water-insoluble.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, the content of this invention is not limited by this.

Synthesis method A: Synthesis of resin (C-1) (radical polymerization)
t-Butyl methacrylate was dissolved in cyclohexanone to prepare 100 mL of a 20% solid content solution. To this solution, 5 mol% of a polymerization initiator V-601 manufactured by Wako Pure Chemical Industries, Ltd. was added, and this was added dropwise to 30 mL of cyclohexanone heated to 80 ° C. over 6 hours in a nitrogen atmosphere. After completion of dropping, the reaction solution was stirred for 2 hours to obtain a reaction solution (C-1). After completion of the reaction, the reaction solution (C-1) was cooled to room temperature, crystallized in 1 L of methanol, and the precipitated white powder was collected by filtration to recover the target resin (C-1).
The weight average molecular weight in terms of standard polystyrene determined by GPC measurement was 12000, and the degree of dispersion was 2.0.

Synthesis method A: Synthesis of resin (C-12) (radical polymerization)
4-t-butylstyrene was dissolved in tetrahydrofuran to prepare 50 g of a 20% solid content solution. To this solution, 6 mol% of a polymerization initiator V-65 manufactured by Wako Pure Chemical Industries, Ltd. was added and stirred for 6 hours in a nitrogen atmosphere to obtain a reaction solution (C-12). After completion of the reaction, 15 mL of tetrahydrofuran was added and the reaction solution (C-12) was cooled to room temperature, crystallized in 600 mL of methanol, and the precipitated white powder was collected by filtration to obtain the target resin (C-12). It was collected.
The weight average molecular weight in terms of standard polystyrene determined by GPC measurement was 4800, and the degree of dispersion was 1.6.

Synthesis method A: Synthesis of resin (C-10) (radical polymerization)
4-t-butylstyrene and acrylic acid (4-t-butylcyclohexyl) were charged at a ratio of 50/50 and dissolved in propylene glycol monomethyl ether acetate (PGMEA) to prepare 100 mL of a 20% solid content solution. 7 mol% of a polymerization initiator V-601 manufactured by Wako Pure Chemical Industries, Ltd. was added to this solution, and this was added dropwise to 30 mL of propylene glycol monomethyl ether acetate heated to 80 ° C. over 6 hours in a nitrogen atmosphere. The reaction liquid was stirred for 2 hours after completion | finish of dripping, and the reaction liquid (C-10) was obtained. After completion of the reaction, the reaction solution (C-10) was cooled to room temperature, crystallized in 1 L of methanol, and the precipitated white powder was collected by filtration to recover the target resin (C-10).
The weight average molecular weight in terms of standard polystyrene determined by GPC measurement was 7800, and the degree of dispersion was 2.5.

Synthesis Method B Synthesis of resin (C-8) (solvent fractionation)
20 g of resin (C-8) having a weight average molecular weight of 4500 and a dispersity of 1.8 was dissolved in 100 g of propylene glycol monomethyl ether acetate and charged into 1000 g of methanol.
The precipitated solid was collected by filtration. After dissolving again in 80 mL of propylene glycol monomethyl ether acetate, this was dropped into methanol and the target resin (C-8) was recovered.
The weight average molecular weight in terms of standard polystyrene determined by GPC measurement was 6000, and the degree of dispersion was 1.3.

Synthesis Method C Synthesis of Resin (C-8) (Living Radical Polymerization)
16 g of 4-t-butylstyrene, 65 g of propylene glycol monomethyl ether (PGME), 0.69 g of a polymerization initiator V-601 manufactured by Wako Pure Chemical Industries, Ltd., and 0.82 g of the following compound are mixed. This was stirred at 90 ° C. for 8 hours while expanding sales in the presence of nitrogen. After completion, the polymerization solution was allowed to cool to 30 ° C. or lower. Thereafter, 1.0 g of V-601 was added to the polymerization solution, heated to 80 ° C., stirred for 8 hours, and subjected to terminal treatment. After completion of the reaction, the solution was allowed to cool to cool to 30 ° C. or lower and dropped into 1000 mL of methanol. The precipitated white powder was collected by filtration and dried at 40 ° C. for 12 hours to obtain 9.5 g of the desired resin (C-8).
The weight average molecular weight in terms of standard polystyrene determined by GPC measurement was 6000, and the degree of dispersion was 1.2.

Other resins were synthesized by any one of the methods described above.
Regarding the resins (C-33) to (C-40), the corresponding polystyrene can be synthesized by hydrogenation in the presence of rhodium / carbon or rhodium / alumina catalyst. You may react under pressure as needed.

Synthesis of Resin (A) Resin (A-1) was synthesized according to the synthesis method of Resin A2 in JP-A-2004-78153. That is, under a nitrogen stream, 90 g of cyclohexanone was placed in a three-necked flask and heated to 80 ° C. To this, 24.8 g of 2-ethyladamantyl methacrylate, 11.8 g of hydroxyadamantyl methacrylate, 8.5 g of γ-butyrolactone methacrylate, and 8 mol% of a polymerization initiator V-601 (manufactured by Wako Pure Chemical Industries) were dissolved in 90 g of cyclohexanone. The solution was added dropwise over 6 hours. After completion of dropping, the reaction was further carried out at 80 ° C. for 2 hours. The reaction solution was allowed to cool and then added dropwise to a mixed solution of 1500 ml of hexane / 400 ml of ethyl acetate over 20 minutes, and the precipitated powder was collected by filtration and dried to obtain 37 g of Resin (A-1). The weight average molecular weight of the obtained resin was 8800 in terms of standard polystyrene, and the dispersity (Mw / Mn) was 2.2.
Resin (A-2) was synthesized in the same manner as in Example (Synthesis Example 3) of JP-A-2005-156726. Resin (A-4) was synthesized by the same method as in Example of JP-A No. 2004-175981. Resin (A-5) was synthesized by the same method as in Example 2 of JP-A No. 2004-124082. Resin (A-7) was synthesized in the same manner as in Example 1 of JP-A-2005-331918. Other resins were synthesized by the same method as that for the resin (A-1).
The structure and composition of the acid-decomposable resin (A) used in the examples, the molecular weight, and the like are shown below. The composition indicates the resin structural formula number and the composition ratio (in order from the left in the structural formula).

Examples and Comparative Examples <Resist Preparation>
The components shown in Table 3 below were dissolved in a solvent, and a solution having a solid content of 7% by mass was prepared for each, and this was filtered through a polyethylene filter having a pore size of 0.1 μm to prepare a positive resist solution. The prepared positive resist composition was evaluated by the following method, and the results are shown in the following table. In addition, about each component in a table | surface, ratio when using two or more is mass ratio.

[Image performance test]
(Exposure condition (1))
An organic antireflection film ARC29A (Nissan Chemical Co., Ltd.) was applied on a silicon wafer and baked at 205 ° C. for 60 seconds to form a 78 nm antireflection film. The positive resist composition prepared thereon was applied and baked at 120 ° C. for 60 seconds to form a 200 nm resist film. The obtained wafer was subjected to pattern exposure using an ArF excimer laser scanner (PAS5500 / 1100, NA0.75, σo / σi = 0.85 / 0.55, manufactured by ASML). Thereafter, heating was performed at 130 ° C. for 60 seconds, followed by development with an aqueous tetramethylammonium hydroxide solution (2.38 mass%) for 30 seconds, rinsing with pure water, and spin drying to obtain a resist pattern.

(Exposure condition (2))
This condition is to form a resist pattern by an immersion exposure method using pure water.
An organic antireflection film ARC29A (Nissan Chemical Co., Ltd.) was applied on a silicon wafer and baked at 205 ° C. for 60 seconds to form a 78 nm antireflection film. The positive resist composition prepared thereon was applied and baked at 120 ° C. for 60 seconds to form a 200 nm resist film. The obtained wafer was subjected to pattern exposure using an ArF excimer laser immersion scanner (NA 0.85). Ultra pure water was used as the immersion liquid. Thereafter, heating was performed at 130 ° C. for 60 seconds, followed by development with an aqueous tetramethylammonium hydroxide solution (2.38 mass%) for 30 seconds, rinsing with pure water, and spin drying to obtain a resist pattern.

(Evaluation method for film loss)
The pattern profile of 90 nm line / 900 nm space (isolated pattern) at the exposure amount for reproducing the mask pattern of 75 nm line / 75 nm space was evaluated.
A rectangle was marked with ◯, a film with a slight film loss was marked with Δ, and a film with a large film loss was marked with x.

[Line edge roughness (LER)]
For the range of 5 μm edge in the longitudinal direction of the line pattern, measure the distance from the reference line where the edge should be at 50 points with a length measuring SEM (S-8840, manufactured by Hitachi, Ltd.), calculate the standard deviation, and calculate 3σ did. A value of less than 5.0 nm was indicated as ◯, a value of 5.0 to 7.0 nm as Δ, and a value greater than 7.0 nm as ×. A smaller value indicates better performance.

[Development defect evaluation]
Using a defect inspection device KLA2360 (trade name) manufactured by KLA-Tencor Corporation, the pixel size of the defect inspection device is set to 0.16 μm, the threshold value is set to 20, and measurement is performed in a random mode. The number of development defects (number / cm ² ) per unit area was calculated by detecting development defects extracted from the differences caused by the pixel unit overlap. A value of less than 0.5 was evaluated as ◯, a value of 0.5 to 0.8 was evaluated as Δ, and a value of greater than 0.8 was evaluated as ×. A smaller value indicates better performance.

[Measurement of receding contact angle]
The prepared positive resist composition was applied onto a silicon wafer and baked at 120 ° C. for 60 seconds to form a 200 nm resist film. The receding contact angle of water droplets was measured by the expansion / contraction method of a dynamic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.). An initial droplet size of 100 μL was sucked at a speed of 6 μL / second for 8 seconds, and a value with a stable dynamic contact angle during suction was defined as a receding contact angle.
[Water followability]
The prepared positive resist composition was applied on a silicon wafer and baked at 130 ° C. for 60 seconds to form a 160 nm resist film. Next, as shown in FIG. 1, pure water 2 was filled between the wafer 1 coated with the obtained positive resist composition and the quartz glass substrate 3. In this state, the quartz glass substrate 3 was moved (scanned) in parallel to the surface of the resist-coated substrate 1, and the state of the pure water 2 following it was visually observed. The scanning speed of the quartz glass substrate 3 is gradually increased, and the pure water 2 cannot follow the scanning speed of the quartz glass substrate 3 to obtain the limit scanning speed (mm / second) at which water droplets start to remain on the retreat side. Follow-up was evaluated. As this limit scan speed is larger, water can follow a higher scan speed, and the water followability on the resist film is better.

The symbols in Table 3 are as follows.
The acid generator corresponds to that exemplified above.

N-1: N, N-dibutylaniline N-2: N, N-dihexylaniline N-3: 2,6-diisopropylaniline N-4: tri-n-octylamine N-5: N, N-dihydroxyethyl Aniline N-6: 2,4,5-triphenylimidazole N-7: Tris (methoxyethoxyethyl) amine N-8: 2-phenylbenzimidazole

W-1: Megafuck F176 (manufactured by Dainippon Ink & Chemicals, Inc.)
(Fluorine)
W-2: Megafuck R08 (Dainippon Ink Chemical Co., Ltd.)
(Fluorine and silicon)
W-3: Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.)
(Silicon)
W-4: Troisol S-366 (manufactured by Troy Chemical Co., Ltd.)
W-5: PF656 (manufactured by OMNOVA, fluorine-based)
W-6: PF6320 (manufactured by OMNOVA, fluorine-based)

SL-1: Cyclohexanone SL-2: Propylene glycol monomethyl ether acetate (PGMEA)
SL-3: Ethyl lactate SL-4: Propylene glycol monomethyl ether (PGME)
SL-5: γ-butyrolactone SL-6: Propylene carbonate

  As a result, the positive resist composition of the present invention has good line edge roughness performance and film reduction performance not only in normal exposure but also in immersion exposure, has few development defects, and in immersion exposure. It can be seen that the followability to the immersion liquid is also good.

Schematic diagram of water followability evaluation method

Explanation of symbols

1 Wafer on which resist film is formed 2 Pure water 3 Quartz glass substrate

Claims (9)

(A) a resin whose solubility in an alkaline developer is increased by the action of an acid;
(B) a compound that generates an acid upon irradiation with an actinic ray or radiation,
(C) a hydrophobic resin having neither a fluorine atom nor a silicon atom, a molecular weight dispersity of 1.3 or less and a weight average molecular weight of 1.0 × 10 ⁴ or less, and (D) a solvent. A positive resist composition characterized by the above. The positive resist composition according to claim 1, wherein the resin (C) is a resin having a repeating unit represented by the following general formula (Ca).

In the formula (Ca),
R _a each independently represents a hydrogen atom or an organic group not containing a fluorine atom and a silicon atom.
R _b represents an organic group containing no fluorine atom or silicon atom.
L ₁ represents a single bond or a linking group. 3. The positive resist composition according to claim 1, wherein the resin (C) is a resin having at least one repeating unit selected from the following general formulas (CI) to (C-III): .

In the formulas (CI) to (C-III),
R ₁ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.
R ₂ represents a hydrocarbon group.
P ₁ represents a single bond, an alkylene group, an ether group, or a linking group having two or more thereof.
P ₂ represents a linking group selected from —O—, —NR— (R is a hydrogen atom or an alkyl group), and —NHSO ₂ —.
n represents an integer of 1 to 4.   The positive resist composition according to any one of claims 1 to 3, wherein the addition amount of the resin (C) is 0.1 to 5 mass% with respect to the total solid content in the resist composition.   The positive resist composition according to any one of claims 1 to 4, wherein the resin (C) does not have an element other than a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom.   The positive resist composition according to claim 1, wherein the resin (C) is purified by solvent fractionation.   The positive resist composition according to claim 1, wherein the resin (C) is obtained by living radical polymerization.   The positive resist composition according to claim 1, wherein a receding contact angle of water with respect to a film formed using the positive resist composition is 70 ° or more.   A pattern forming method comprising the steps of: forming a resist film with the positive resist composition according to claim 1; immersion exposure; and developing.

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