JP2006301278A - Positive resist composition for liquid immersion exposure and method for forming pattern using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition for liquid immersion exposure which is used in manufacturing processes of a semiconductor such as an IC, fabrication of a circuit board of a liquid crystal, a thermal head or the like, and other photofabrication processes, and which has improved pattern edge roughness and dry etching durability, and to provide a method for forming a pattern using the composition. <P>SOLUTION: The positive resist composition for liquid immersion exposure contains (A) a resin having at least two kinds of specified repeating units and having solubility to an alkali developing solution increased by an action of an acid, and (B) a compound generating an acid upon irradiation with active rays or radiation. The method for forming a pattern is carried out by using the composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a positive resist composition for immersion exposure 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, and a pattern using the same. The present invention relates to a forming method. In particular, the present invention relates to a positive resist composition for immersion exposure suitable for exposure by an immersion projection exposure apparatus using far ultraviolet light having a wavelength of 300 nm or less as a light source, and a pattern forming method using the same.

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 include Patent Document 1 (Japanese Patent Laid-Open No. 57-153433) and Patent Document 2 (Japanese Patent Laid-Open No. 7-220990). There is no discussion of resists suitable for immersion exposure techniques.
Recent progress in immersion exposure technology is described in Non-Patent Document 1 (SPIE Proc 4688, 11 (2002)), Non-Patent Document 2 (J. Vac. Sci. Tecnol. B 17 (1999)), Non-Patent Document 3 (SPIE Proc 3999,2 (2000)), Patent Document 3 (Japanese Patent Laid-Open No. 10-303114), Patent Document 4 (International Publication WO 2004-077158 Pamphlet) 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 F2 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, but a sufficient product has not yet been found in terms of environmental safety and refractive index. It has not been. 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. 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 during exposure, and the generated acid is used as a reaction catalyst in post-exposure baking (PEB). In this image forming method, the alkali-insoluble group is changed to an alkali-soluble group, and the exposed portion is removed by alkali development.

It is pointed out that when 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. Patent Document 5 (International Publication WO 2004-068242 pamphlet) describes an example in which resist performance is changed by immersing a resist for ArF exposure in water before and after exposure, and points to a problem in immersion exposure. .
For example, when a chemically amplified resist is subjected to immersion exposure, it is necessary to improve pattern edge roughness. In particular, thin-film resists have insufficient dry etching resistance and need to be improved.

  On the other hand, Patent Document 6 (Japanese Patent Laid-Open No. 10-1111569) introduces a radiation sensitive resin composition containing a resin having an alicyclic hydrocarbon structure in the main chain.

JP-A-57-153433 JP-A-7-220990 JP-A-10-303114 International Publication WO2004-077158 Pamphlet International Publication WO 2004-068242 Pamphlet JP 10-1111569 A Proc. SPIE, 2002, Vol. 4688, p. 11 J.Vac.Sci.Tecnol.B 17 (1999) Proc. SPIE, 2000, Vol. 3999, p. 2

  An object of the present invention is to provide a positive resist composition suitable for immersion exposure with improved pattern edge roughness and dry etching resistance, and pattern formation using the same, in view of the problems of the conventional immersion exposure techniques as described above. It is to provide a method.

  The present invention is as follows, whereby the above-mentioned object of the present invention is achieved.

(1) (A) a resin having a repeating unit represented by the following general formula (A1) and a repeating unit represented by the following general formula (A2), whose solubility in an alkali developer is increased by the action of an acid; (B) A positive resist composition for immersion exposure, comprising a compound that generates an acid upon irradiation with actinic rays or radiation.

In general formula (A1),
X and Y each independently represent a methylene group, an ethylene group, an oxygen atom or a sulfur atom.
R ₁ and R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, a cyano group or a hydroxyl group.
R ₂ and R ₃ are each independently a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, a cyano group, a hydroxyl group, a group having a lactone ring, —COOH, —COOR _5a , —C (═O) —Xa -A'-R < _6a >, -OR < _7a >, -COR < _8a > or an acid-decomposable group is shown.
R _5a represents an alkyl group, a cycloalkyl group, or a group having a lactone ring.
Xa 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 _6a represents —COOH, —COOR _5a , —CN, a hydroxyl group, an alkyl group, an alkoxy group, —CO—NH—R _9a , —CO—NH—SO ₂ —R _9a or a group having a lactone ring.
R _7a and R _8a represent a hydrogen atom, an alkyl group, a cycloalkyl group or a group having a lactone ring.
R _9a represents an alkyl group or a cycloalkyl group.
At least two of R _{1 to} R ₄ may form a divalent linking group to form a ring.
n is 0 or 1.
In general formula (A2),
R ₅ represents an alkyl group, a cycloalkyl group or a group having a lactone ring.

(2) The positive resist composition for immersion exposure according to (1), wherein R ₅ in the general formula (A2) is a group having a lactone ring.

(3) The positive resist composition for immersion exposure according to (1) or (2), wherein R ₅ in the general formula (A2) is a group having a cyclic hydrocarbon structure.

  (4) The liquid immersion according to any one of (1) to (3), wherein the total solid concentration in the positive resist composition for liquid immersion exposure is 2.0 to 6.0% by mass. A positive resist composition for exposure.

  (5) A process comprising: forming a resist film from the positive resist composition for immersion exposure according to any one of (1) to (4); exposing the resist film to immersion exposure; and developing the resist film. Pattern forming method.

  (6) The pattern forming method as described in (5), wherein immersion exposure is performed through a medium having a refractive index of 1.5 or more.

  (7) The pattern forming method as described in (5) or (6), wherein the resist film has a thickness of 30 to 100 nm.

  (8) The pattern forming method as described in any one of (5) to (7), wherein a protective film is formed on the resist film.

  According to the present invention, it is possible to provide a positive resist composition suitable for immersion exposure with improved pattern edge roughness and dry etching resistance, and a pattern forming method using the same.

Hereinafter, the compounds used in 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 has a substituent with what does not have 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 having a repeating unit represented by the general formula (A1) and a repeating unit represented by the general formula (A2) whose solubility in an alkaline developer is increased by the action of an acid. The positive resist composition for use has a repeating unit represented by the following general formula (A1) and a repeating unit represented by the following general formula (A2), and the solubility in an alkali developer is increased by the action of an acid. Resin (hereinafter also referred to as “resin (A)”).

In general formula (A1),
X and Y each independently represent a methylene group, an ethylene group, an oxygen atom or a sulfur atom.
R ₁ and R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, a cyano group or a hydroxyl group.
R ₂ and R ₃ are each independently a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, a cyano group, a hydroxyl group, a group having a lactone ring, —COOH, —COOR _5a , —C (═O) —Xa -A'-R < _6a >, -OR < _7a >, -COR < _8a > or an acid-decomposable group is shown.
R _5a represents an alkyl group, a cycloalkyl group, or a group having a lactone ring.
Xa 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 _6a represents —COOH, —COOR _5a , —CN, a hydroxyl group, an alkyl group, an alkoxy group, —CO—NH—R _9a , —CO—NH—SO ₂ —R _9a or a group having a lactone ring.
R _7a and R _8a represent a hydrogen atom, an alkyl group, a cycloalkyl group or a group having a lactone ring.
R _9a represents an alkyl group or a cycloalkyl group.
At least two of R _{1 to} R ₄ may form a divalent linking group to form a ring.
n is 0 or 1.
In general formula (A2),
R ₅ represents an alkyl group, a cycloalkyl group or a group having a lactone ring.

Examples of the alkyl group in the alkyl group and the alkoxy group in the general formulas (A1) to (A2) include linear or branched alkyl groups having 1 to 4 carbon atoms. The alkyl group may have a substituent.
Examples of the cycloalkyl group in the general formulas (A1) to (A2) include a cycloalkyl group having 5 to 20 carbon atoms. The cycloalkyl group may be monocyclic or polycyclic. The cycloalkyl group may have an oxygen atom in the ring.

  Specific examples of the cycloalkyl group include groups having a monocyclo, bicyclo, tricyclo, or tetracyclo structure having 5 or more carbon atoms. The carbon number is preferably 6-30, and more 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 linking group in A ′ is selected from the group consisting of 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 and a urea group, or 2 A combination of two or more groups can be mentioned, and a single bond is preferable.

Examples of the divalent linking group when at least two of R _{1 to} R ₄ form a divalent linking group to form a ring include, for example, an oxy group, a carbonyl group, and an alkylene group (preferably having a carbon number of 1 -5), -NH-, -N (OH)-, or a combination of two or more thereof may be mentioned, and the ring may have a double bond.

  The repeating unit represented by the general formula (A1) and the repeating unit represented by the general formula (A2) have a group (also referred to as “acid-decomposable group”) that is decomposed by the action of an acid to be alkali-soluble. Is preferred. Examples of the acid-decomposable group include a group in which an alkali-soluble group is protected by a tertiary ester or an acetal structure.

  Examples of the alkali-soluble group include various groups known in this technical field. Specific examples include a carboxylic acid group, a sulfonic acid group, a phenol group, and a thiol group, and a carboxylic acid group is preferable.

  A preferred form of the acid-decomposable group is a structure in which the hydrogen atom of the carboxylic acid group is substituted with a structure represented by the following general formulas (pI) to (pV).

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, provided that at least one of R _{12 to} R ₁₄ , or R ₁₅ , Any of 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, provided that at least one of R _{17 to} R ₂₁ is cyclo Represents an alkyl 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, provided that at least one of R _{22 to} R ₂₅ is cyclo Represents an alkyl group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

  Among (pI) to (pV), (pI) or (pII) is preferable, and 2-alkyladamantane, 2-alkylnorbornane, and adamantylalkyl groups are more preferable.

  The repeating unit represented by the general formula (A1) and the repeating unit represented by the general formula (A2) preferably have a group having a lactone ring. As the group having a lactone ring, any group having a lactone ring can be used, but a group having a 5- to 7-membered ring lactone structure is preferred, and a bicyclo lactone structure is added to the bicyclo lactone structure. A structure in which another ring structure is condensed to form a structure or a spiro structure is preferable. A group having a lactone structure represented by any of the following general formulas (LC1-1) to (LC1-16) is more preferable. Further, a group having a lactone structure may be directly bonded to the main chain. Preferable lactone structures are (LC1-1) (LC1-4) (LC1-5) (LC1-6) (LC1-13) (LC1-14). By using the lactone structure, line edge roughness and development defects Will be better.

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. n2 represents an integer of 0 to 4. When n2 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.

  The repeating unit represented by the general formula (A1) and the repeating unit represented by the general formula (A2) preferably have an alkali-soluble group such as a hydroxyl group or a carboxyl group, and more preferably have a carboxyl group. By having these, the resolution in contact hole applications increases.

The repeating unit represented by the general formula (A1) and the repeating unit represented by the general formula (A2) preferably have a group represented by the following 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.

  Specific examples of the repeating unit represented by the general formula (A1) or the general formula (A2) are shown below, but the present invention is not limited to these specific examples.

  The resin (A) preferably has a repeating unit represented by the following general formula (pA) as a repeating unit having an acid-decomposable group.

In the general formula (pA), 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 represents 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 urea group, or a combination of two or more groups. Represents. A single bond is preferable.
Rp ₁ represents any one of the general formulas (pI) to (pV).

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

  Specific examples of the repeating unit represented by the general formula (pA) are shown below.

In the above structural formulas, Rx represents H, CH ₃ , CF ₃ or CH ₂ OH, and Rxa and Rxb each independently represents an alkyl group having 1 to 4 carbon atoms.

  Resin (A) adjusts dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and resolution, heat resistance, sensitivity, etc., which are general required characteristics of resist, in addition to the above repeating structural units. For this purpose, various repeating structural units can be contained.

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

Thereby, the performance required for the resin (A), in particular,
(1) Solubility in coating solvent,
(2) Film formability (glass transition point),
(3) Alkali developability,
(4) Membrane slip (hydrophobic, alkali-soluble group selection),
(5) Adhesion of unexposed part to substrate,
(6) Dry etching resistance,
Etc. can be finely adjusted.

  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 resin (A), the molar ratio of each repeating structural unit is the resist dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and the general required performance of the resist, resolving power, heat resistance, sensitivity. It is set appropriately in order to adjust etc.

  In the resin (A), the content of the repeating unit represented by the general formula (A1) is preferably 10 to 60 mol%, more preferably 15 to 55 mol%, still more preferably 20 to 50 in all repeating structural units. Mol%.

  In the resin (A), the content of the repeating unit represented by the general formula (A2) is preferably 10 to 60 mol%, more preferably 15 to 55 mol%, still more preferably 20 to 50 in all repeating structural units. Mol%.

  In the 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 mol% in all repeating structural units. is there.

  When the 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 resin (A) used in the present invention is preferably one in which all of the repeating units are composed of (meth) acrylate repeating units. In this case, all of the repeating units may be methacrylate, all of the repeating units may be acrylate, or a mixture of methacrylate / acrylate, but the acrylate repeating unit is preferably 50 mol% or less of all repeating units.

  The resin (A) preferably has a weight average molecular weight in the range of 1500 to 100,000, more preferably in the range of 2000 to 70000, and particularly preferably in the range of 3000 to 50000. The resin (A) preferably has a dispersity (Mw / Mn) of 1.2 to 3.0.

The resin (A) 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 and 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, generation | occurrence | production of the particle at the time of a preservation | save can be suppressed.
The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. As the 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 50 to 100 ° C.

  In the present invention, the addition amount of the resin (A) in the positive resist composition for immersion exposure is 50 to 99.7% by mass, preferably 70 to 99.5% by mass, based on the total solid content. In addition to the resin in the present invention, other resins can be used as necessary. In the composition of the present invention, the preferred range of use of other resins can be mixed at a ratio of 70 parts by mass or less, particularly preferably 50 parts by mass or less, per 100 parts by mass of the resin (A) in the present invention.

(B) Compound that generates acid upon irradiation with actinic ray or radiation Compound that generates acid upon irradiation with actinic ray or radiation (hereinafter referred to as “acid generator”) used in the positive resist composition for immersion exposure of the present invention. Will be described below.
The acid generator used in the present invention can be selected from compounds generally used as an acid generator.
That is, it generates an acid upon irradiation with actinic rays or radiation used for photoinitiators of photocationic polymerization, photoinitiators of photoradical polymerization, photodecolorants of dyes, photochromic agents, or microresists. Known compounds 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, for example, US Pat. No. 3,849,137, German Patent No. 3914407. JP, 63-26653, JP, 55-164824, JP, 62-69263, JP, 63-146038, JP, 63-163452, JP, 62-153853, The compounds described in 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.

  Preferred compounds among the acid generators include compounds represented by the following general formulas (ZI), (ZII), and (ZIII).

In the general formula (ZI),
R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
X ⁻ represents a non-nucleophilic anion.

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, aryldicycloalkylsulfonium compounds, and the like.

  The aryl group of the arylsulfonium compound is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. The aryl group may be an aryl group having a heterocyclic structure having an oxygen atom, a nitrogen atom, a sulfur atom or the like. Examples of the aryl group having a heterocyclic structure include a pyrrole residue (a group formed by removing one hydrogen atom from pyrrole) and a furan residue (a group formed by removing one hydrogen atom from furan). Groups), thiophene residues (groups formed by removing one hydrogen atom from thiophene), indole residues (groups formed by removing one hydrogen atom from indole), etc. it can. 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.

The aryl group, alkyl group, and cycloalkyl group of R _{201 to} R ₂₀₃ are an alkyl group (for example, having 1 to 15 carbon atoms), a cycloalkyl group (for example, having 3 to 15 carbon atoms), an aryl group (for example, having 6 to 6 carbon atoms) 14), an alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, a phenylthio group or the like may be used as a substituent. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and alkoxy groups having 1 to 12 carbon atoms, most preferably alkyl having 1 to 4 carbon atoms. Group, 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.

Examples of the non-nucleophilic anion as X ⁻ include a sulfonate anion, a carboxylate anion, a sulfonylimide anion, a bis (alkylsulfonyl) imide anion, and a tris (alkylsulfonyl) methyl anion.

  A non-nucleophilic anion is an anion that has an extremely low ability to cause a nucleophilic reaction, and is an anion that can suppress degradation over time due to an intramolecular nucleophilic reaction. This improves the temporal stability of the resist.

  Examples of the sulfonate anion include an aliphatic sulfonate anion, an aromatic sulfonate anion, and a camphor sulfonate anion.

  Examples of the carboxylate anion include an aliphatic carboxylate anion, an aromatic carboxylate anion, and an aralkylcarboxylate anion.

  Examples of the aliphatic group in the aliphatic sulfonate anion include, for example, an alkyl group having 1 to 30 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, sec- Butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl And an eicosyl group and a cycloalkyl group having 3 to 30 carbon atoms, specifically, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornyl group, a boronyl group, and the like.

  The aromatic group in the aromatic sulfonate anion is preferably an aryl group having 6 to 14 carbon atoms, such as a phenyl group, a tolyl group, and a naphthyl group.

  The alkyl group, cycloalkyl group, and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion may have a substituent.

  Examples of such substituents include nitro groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), carboxyl groups, hydroxyl groups, amino groups, cyano groups, and alkoxy groups (preferably having 1 to 5 carbon atoms). ), A cycloalkyl group (preferably 3 to 15 carbon atoms), an aryl group (preferably 6 to 14 carbon atoms), an alkoxycarbonyl group (preferably 2 to 7 carbon atoms), an acyl group (preferably 2 to 12 carbon atoms). ), An alkoxycarbonyloxy group (preferably having 2 to 7 carbon atoms), an alkylthio group (preferably having 1 to 15 carbon atoms), and the like. About the aryl group and ring structure which each group has, an alkyl group (preferably C1-C15) can further be mentioned as a substituent.

  Examples of the aliphatic group in the aliphatic carboxylate anion include those similar to the aliphatic group in the aliphatic sulfonate anion.

  Examples of the aromatic group in the aromatic carboxylate anion include the same aromatic groups as in the aromatic sulfonate anion.

  The aralkyl group in the aralkyl carboxylate anion is preferably an aralkyl group having 6 to 12 carbon atoms, such as a benzyl group, a phenethyl group, a naphthylmethyl group, a naphthylethyl group, and a naphthylmethyl group.

  The aliphatic group, aromatic group and aralkyl group in the aliphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion may have a substituent. Examples of the substituent include aliphatic sulfonic acid The same halogen atom, alkyl group, cycloalkyl group, alkoxy group, alkylthio group and the like as in the anion can be exemplified.

  Examples of the sulfonylimide anion include saccharin anion.

  The alkyl group in the bis (alkylsulfonyl) imide anion and tris (alkylsulfonyl) methyl anion is preferably an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, An isobutyl group, a sec-butyl group, a pentyl group, a neopentyl group, and the like can be given. These alkyl groups may have a substituent, and examples of the substituent include a halogen atom, an alkyl group substituted with a halogen atom, an alkoxy group, an alkylthio group, and the like, which are substituted with a fluorine atom. Alkyl groups are preferred.

  Examples of other non-nucleophilic anions include fluorinated phosphorus, fluorinated boron, and fluorinated antimony.

Examples of the non-nucleophilic anion of X ⁻ include an aliphatic sulfonate anion in which the α-position of the sulfonic acid is substituted with a fluorine atom, an aromatic sulfonate anion substituted with a fluorine atom or a group having a fluorine atom, and an alkyl group. A bis (alkylsulfonyl) imide anion substituted with a fluorine atom and a tris (alkylsulfonyl) methide anion wherein an alkyl group is substituted with a fluorine atom are preferred. The non-nucleophilic anion is more preferably a perfluoro aliphatic sulfonate anion having 4 to 8 carbon atoms, an aromatic sulfonate anion having a fluorine atom, particularly preferably a nonafluorobutane sulfonate anion, a perfluorooctane sulfonate anion, It is a pentafluorobenzenesulfonic acid anion and 3,5-bis (trifluoromethyl) benzenesulfonic acid anion.

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 not containing an 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 either linear or branched, and is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. Butyl group, pentyl group and the like. More preferable examples of the alkyl group include a 2-linear or branched oxoalkyl group and an alkoxycarbonylmethyl group.

The cycloalkyl group as R ₂₀₁ to R ₂₀₃ is preferably a cycloalkyl group having 3 to 10 carbon atoms, e.g., cyclopentyl, cyclohexyl group and a norbornyl group. More preferred examples of the cycloalkyl group include a 2-oxocycloalkyl group.

  The 2-oxoalkyl group may be linear, branched or cyclic, and preferably includes a group having> C═O at the 2-position of the above alkyl group or cycloalkyl group.

  The alkoxy group in the alkoxycarbonylmethyl group is preferably an alkoxy group having 1 to 5 carbon atoms (methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group).

R _{201 to} R ₂₀₃ may be further substituted with a halogen atom, an alkoxy group (eg, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, a nitro group, or the like.

  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 _5c , R _6c and R _7c , and Rx and Ry may be bonded to each other to form a ring structure, which is an oxygen atom, sulfur atom, ester A bond or an amide bond may be included. Any two or more of R _1c to R _5c, as the group R _6c and R _7c, and the Rx and Ry are formed in combination, there can be mentioned a butylene group and a pentylene group.

Zc ⁻ represents a non-nucleophilic anion, and examples thereof include the same as the non-nucleophilic anion of X ^{− in} formula (ZI).

The alkyl group as R _{1c to} R _7c is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, A linear or branched pentyl group can be exemplified.

The cycloalkyl group as R _{1c to} R _7c is preferably a cycloalkyl group having 3 to 8 carbon atoms, and examples thereof include a cyclopentyl group and 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.

The alkyl group as Rx and Ry, cycloalkyl groups, alkyl groups as R _1c to R _7c, can be the same as the cycloalkyl group, a 2-oxoalkyl group, a 2-oxocycloalkyl group, an alkoxy A carbonylmethyl group is more preferred.

Examples of the 2-oxoalkyl group and 2-oxocycloalkyl 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 .

  Rx and Ry are preferably alkyl groups 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.

The aryl group of R ₂₀₄ to R _207, a phenyl group, a naphthyl group, more preferably a phenyl group.

The alkyl group as R ₂₀₄ to R ₂₀₇ is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group).

The cycloalkyl group as R ₂₀₄ to R ₂₀₇ is preferably a cycloalkyl group having 3 to 10 carbon atoms, e.g., cyclopentyl, cyclohexyl group and a norbornyl group.

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).

  Preferred examples of the acid generator include compounds represented by the following general formulas (ZIV), (ZV), and (ZVI).

In general formulas (ZIV) to (ZVI),
Ar ₃ and Ar ₄ each independently represents an aryl group.
R ₂₀₆ represents an alkyl group, a cycloalkyl group or an aryl group.
_R207 and _R208 each independently represents an alkyl group, a cycloalkyl group, an aryl group, or a cyano group.
These alkyl group, a cycloalkyl group, an aryl group, an alkyl group as R ₂₀₄ to R _207, cycloalkyl group is the same as the aryl group.
A represents an alkylene group, an alkenylene group or an arylene group.

  Among the acid generators, compounds represented by the general formulas (ZI) to (ZIII) are more preferable.

  As the acid generator in the present invention, particularly preferably, an anion structure containing an alkyl group having 4 or less carbon atoms substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, or an aromatic group substituted with a fluorine atom; An acid generator having a triarylsulfonium cation structure. Such acid generators are preferably those represented by the following general formulas (B1) to (B3).

In general formulas (B1) to (B3),
R ₁ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, an alkoxy group or a halogen atom.
y represents 0 or an integer of 1 to 5 independently of each other. When y is an integer of 2 or more, two or more R _{1 s} may be the same or different.
Q _{1 to} Q ₄ are each independently an alkyl group having 1 to 8 carbon atoms substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom, or a fluorinated alkyl group. Represents a substituted aryl group.

As the alkyl group for R ₁ , a linear or branched alkyl group having 1 to 15 carbon atoms is preferable, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, and a t-butyl group. Can be mentioned.
The alicyclic hydrocarbon group for R ₁ is preferably a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.
The alkyl group substituted with a fluorine atom Q ₁ to Q _4, for _{example, -CF 3, -C 2 F 5} , -n-C 3 F 7, -n-C 4 F 9, -n-C 8 _{F 17, -CF (CF 3)} 2, -CH (CF 3) 2, - (CF 2) 2 OCF 2 CF 3, - (CF 2) 2 O (CH 2) 3 CH 3, - (CF 2) _{2 O (CH 2) 13 CH} 3, - (CF 2) 2 O (CF 2) 2 (CH 2) 3 CH 3 and the like. The alkyl group having 4 or less carbon atoms substituted with a fluorine atom of Q _{1 to} Q ₄ may further have a substituent such as an alkoxy group or a fluoroalkoxy group.
Examples of the aryl group substituted with a fluorine atom of Q _{1 to} Q ₄ include 2,3,4,5,6-pentafluorophenyl group, 2,3,4-trifluorophenyl group, and 2,4-difluoro. A phenyl group, 4-fluorophenyl group, 4-undecanyloxy-2,3,5,6-tetrafluorophenyl group and the like can be mentioned.
Examples of the aryl group substituted with a fluorinated alkyl group of Q _{1 to} Q ₄ include a 3-trifluoromethylphenyl group, a 3,5-bis (trifluoromethyl) phenyl group, a 4-trifluoromethylphenyl group, And 4-n-nonafluorobutylphenyl group.

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

An acid generator can be used individually by 1 type or in combination of 2 or more types.
The content of the acid generator in the resist composition for immersion exposure is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably, based on the total solid content of the resist composition. Is 1-7 mass%.

(C) A dissolution inhibiting compound having a molecular weight of 3000 or less (hereinafter also referred to as a “dissolution inhibiting compound”) that is decomposed by the action of an acid to increase the solubility in an alkaline developer.
The resist composition for immersion exposure of the present invention contains a dissolution inhibiting compound (hereinafter also referred to as “dissolution inhibitor”) having a molecular weight of 3000 or less, which is decomposed by the action of an acid to increase the solubility in an alkaline developer. It is preferable to do.
As a dissolution inhibitor, an alicyclic ring having an acid-decomposable group such as a cholic acid derivative containing an acid-decomposable group described in Proceeding of SPIE, 2724, 355 (1996) is used in order not to lower the permeability of 220 nm or less. Aliphatic or aliphatic compounds are preferred. Examples of the acid-decomposable group and alicyclic structure are the same as those described for the resin as the component (A).
The molecular weight of the dissolution inhibitor in the present invention is 3000 or less, preferably 300 to 3000, and more preferably 500 to 2500.

  The addition amount of the dissolution inhibitor is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, based on the total solid content of the positive resist composition for immersion exposure.

  Although the specific example of a dissolution inhibitor is shown below, it is not limited to these.

(D) Basic compound The positive resist composition for immersion exposure of the present invention preferably contains (D) a basic compound in order to reduce the 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) to (E),
R ²⁰⁰ , R ²⁰¹ and R ²⁰² may be the same or different and are a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. Here, R ²⁰¹ and R ²⁰² may combine with each other to form a ring.

The alkyl group may be unsubstituted or may have a substituent. Examples of the alkyl group having a substituent include an aminoalkyl group having 1 to 20 carbon atoms, a hydroxyalkyl group having 1 to 20 carbon atoms, 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.

Examples of basic compounds include substituted or unsubstituted primary, secondary, and tertiary aliphatic amines, aromatic amines, heterocyclic amines, amide derivatives, imide derivatives, and cyano groups. Examples thereof include nitrogen-containing compounds. Of these, aliphatic amines, aromatic amines, and heterocyclic amines are preferable. Preferred substituents that may be present are an amino group, an alkyl group, an alkoxy group, an acyl group, an acyloxy group, an aryl group, an aryloxy group, a nitro group, a cyano group, an ester group, and a lactone group.
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 based on solid content of the positive resist composition for immersion exposure, 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.

(E) Surfactant The positive resist composition for immersion exposure of the present invention preferably further comprises (E) a surfactant, and is a fluorine-based and / or silicon-based surfactant (fluorine-based surfactant). , A silicon-based surfactant, a surfactant having both a fluorine atom and a silicon atom), or two or more thereof.

When the positive resist composition for immersion exposure of the present invention contains the surfactant (E), adhesion and development can be achieved with good sensitivity and resolution when using an exposure light source of 250 nm or less, particularly 220 nm or less. A resist pattern with few defects can be provided.
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 OMNIVA), 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, surfactants are derived from fluoroaliphatic compounds produced by the telomerization method (also referred to as the telomer method) or the oligomerization method (also referred to as the 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.

  (E) The amount of the surfactant used is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total amount of the positive resist composition for immersion exposure (excluding the solvent). It is.

(F) Organic solvent Examples of the solvent that can be used in preparing the positive resist composition for immersion exposure by dissolving the above-described components include alkylene glycol monoalkyl ether carboxylate and alkylene glycol monoalkyl ether. , Alkyl lactate ester, alkyl alkoxypropionate, cyclic lactone having 4 to 10 carbon atoms, monoketone compound having 4 to 10 carbon atoms which may contain a ring, alkylene carbonate, alkyl alkoxyacetate, alkyl pyruvate, etc. Can do.

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-hexen-2-one, 3-penten-2-one, cyclopentanone, 2-methylcyclopentanone, 3-methylcyclo Pentanone, 2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopentanone, cyclohexanone, 3-methylcyclohexanone, -Methylcyclohexanone, 4-ethylcyclohexanone, 2,2-dimethylcyclohexanone, 2,6-dimethylcyclohexanone, 2,2,6-trimethylcyclohexanone, cycloheptanone, 2-methylcycloheptanone, 3-methylcycloheptanone Preferably mentioned.

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 preferable, 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 weight or more of a solvent not containing a hydroxyl group is particularly preferred from the viewpoint of coating uniformity.

(G) Alkali-soluble resin The positive resist composition for immersion exposure of the present invention further contains an acid-decomposable group, (G) a resin that is insoluble in water and soluble in an alkaline developer. And this improves the sensitivity.
In the present invention, novolak resins having a molecular weight of about 1000 to 20000 and polyhydroxystyrene derivatives having a molecular weight of about 3000 to 50000 can be used as such an alkali-soluble resin. However, they absorb light of 250 nm or less. Since it is large, it is preferable to use it by partially hydrogenating it or using it in an amount of 30% by weight or less of the total resin amount.
A resin containing a carboxyl group as an alkali-soluble group can also be used. The resin containing a carboxyl group preferably has a monocyclic or polycyclic alicyclic hydrocarbon group for improving dry etching resistance. Specifically, a methacrylic acid ester and (meth) acrylic acid copolymer having an alicyclic hydrocarbon structure that does not exhibit acid decomposability, or a (meth) acrylic acid ester having an alicyclic hydrocarbon group having a carboxyl group at the terminal And the like.

(H) Carboxylic acid onium salt Examples of the (H) carboxylic acid onium salt in the present invention include a carboxylic acid sulfonium salt, a carboxylic acid iodonium salt, and a carboxylic acid ammonium salt. In particular, the (H) 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 (H) 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 (H) carboxylic acid onium salt in the composition is suitably from 0.1 to 20% by weight, preferably from 0.5 to 10% by weight, more preferably 1%, based on the total solid content of the composition. -7% by mass.

Other Additives In the positive resist composition for immersion exposure according to the present invention, a dye, a plasticizer, a photosensitizer, a light absorber, and a compound that promotes solubility in a developing solution (for example, if necessary) , A phenol compound having a molecular weight of 1000 or less, an alicyclic compound having a carboxyl group, or an aliphatic compound).

Such phenol 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.

[Physical properties of resist composition]
The positive resist composition for immersion exposure 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 100 nm, from the viewpoint of improving resolution. Such a film thickness can be obtained by setting the solid content concentration in the positive resist composition for immersion exposure to an appropriate range to give an appropriate viscosity and improving the coating property and film forming property. .
The total solid concentration in the positive resist composition for immersion exposure is generally 1 to 10% by mass, more preferably 1 to 8% by mass, and still more preferably 1.0 to 6.0% by mass. .

[Pattern formation method]
The positive resist composition for immersion exposure according to the present invention is used by dissolving the above components in a predetermined organic solvent, preferably the mixed solvent, and applying the solution on a predetermined support as follows.
That is, a positive resist composition for immersion exposure can be applied to 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. It is applied with a thickness (usually 30 to 500 nm). After application, the resist film is washed with immersion water as necessary. The washing time is usually 5 seconds to 5 minutes.
Subsequently, the resist applied by spin or bake is dried to form a resist film, and then exposed through a mask or the like for pattern formation and exposed (immersion exposure) through immersion water. For example, the exposure is performed in a state where the space between the resist film and the optical lens is filled with the immersion liquid. The exposure amount can be set as appropriate, but is usually 1 to 100 mJ / cm ² . After exposure, the resist film is washed with immersion water as necessary. The time is usually 5 seconds to 5 minutes. Subsequently, spin or / and baking is preferably performed, and development and rinsing are performed to obtain a good pattern. It is preferable to perform the said baking, and baking temperature is 30-300 degreeC normally. From the above-mentioned PED point, it is better that the time from the exposure to the baking process is short.
Here, the exposure light is preferably far ultraviolet rays having a wavelength of 250 nm or less, more preferably 220 nm or less. Specific examples include KrF excimer laser (248 nm), ArF excimer laser (193 nm), F2 excimer laser (157 nm), and X-rays.
Incidentally, it is considered that the change in performance observed when the resist is applied to immersion exposure is derived from the contact of the resist surface with the immersion liquid.

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 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.

In order to prevent the resist film from coming into direct contact with the immersion liquid between the resist film formed by the positive resist composition for immersion exposure of the present invention and the immersion liquid, an immersion liquid hardly soluble film (hereinafter referred to as “top”). May also be provided). The necessary functions for the top coat are suitability for application to the upper layer of the resist, radiation, especially transparency to 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.

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 topcoat and the immersion liquid. When the exposure light source is an ArF excimer laser (wavelength: 193 nm), it is preferable to use water as the immersion liquid, so that the top coat for ArF immersion exposure is close to the refractive index of water (1.44). Is preferred. A thin film is more preferable from the viewpoint of transparency and refractive index.

  When an organic solvent is used as the immersion liquid, it is preferable to use a water-soluble top coat.

In the development process, a developer is used as follows. As a developer of a positive resist composition for immersion exposure, inorganic hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, etc. Primary amines, 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, tetraethyl Alkaline aqueous solutions such as quaternary ammonium salts such as ammonium hydroxide and cyclic amines such as pyrrole and pihelidine can be used.
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.
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.

  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.

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

Synthesis Example 1 (Synthesis of Resin (1))
Mixing of N-methylmaleic anhydride and 5-norbornenecarboxylic acid (2-methyladamantyl) ester in a ratio of 50/50 (molar ratio), propylene glycol monomethyl ether acetate / propylene glycol monomethyl ether = 70/30 (mass ratio) It melt | dissolved in the solvent and 450g of solutions with a solid content concentration of 22 mass% were prepared. 6 mol% of a polymerization initiator V-601 manufactured by Wako Pure Chemical Industries, Ltd. was added to this solution, and this was heated to 80 ° C. over 6 hours in a nitrogen atmosphere, propylene glycol monomethyl ether acetate / propylene glycol monomethyl ether = 70 / It was dripped at 50 g of mixed solvents of 30 (mass ratio). After completion of dropping, the reaction solution was stirred for 2 hours to obtain a reaction solution (1). After completion of the reaction, the reaction solution (1) was cooled to room temperature, crystallized in a mixed solvent of 4.5 times the amount of hexane / ethyl acetate = 90/10 (mass ratio), and the precipitated white powder was collected by filtration. The target resin (1) was recovered.
^The polymer composition ratio determined from ¹³ CNMR and acid value titration was 50/50. Moreover, the standard polystyrene conversion weight average molecular weight calculated | required by GPC measurement was 6500, and dispersion degree was 2.1.

  Resins (2) to (8) were synthesized in the same manner as for resin (1).

Synthesis Example 2 (Synthesis of Comparative Resin (9))
Mixing of 2-methyl-2-adamantyl methacrylate, hydroxyadaman methacrylate, and norbornane lactone acrylate at a ratio (molar ratio) of 40/20/40, propylene glycol monomethyl ether acetate / propylene glycol monomethyl ether = 70/30 (mass ratio) It melt | dissolved in the solvent and 450g of solutions with a solid content concentration of 22 mass% were prepared. 6 mol% of a polymerization initiator V-601 manufactured by Wako Pure Chemical Industries, Ltd. was added to this solution, and this was heated to 80 ° C. over 6 hours in a nitrogen atmosphere, propylene glycol monomethyl ether acetate / propylene glycol monomethyl ether = 70 / It was dripped at 50 g of mixed solvents of 30 (mass ratio). After completion of dropping, the reaction solution was stirred for 2 hours to obtain a reaction solution (9). After completion of the reaction, the reaction solution (9) was cooled to room temperature, crystallized in a mixed solvent of 4.5 times the amount of hexane / ethyl acetate = 90/10 (mass ratio), and the precipitated white powder was collected by filtration. The target resin (9) was recovered.
^The polymer composition ratio determined from ¹³ CNMR and acid value titration was 39/20/41. Moreover, the weight average molecular weight of standard polystyrene conversion calculated | required by GPC measurement was 9800, and dispersion degree was 2.1.

  The structures of the resins (1) to (9) are shown below.

Examples 1-8 and Comparative Example 1
[Resist preparation]
The components shown in Table 1 below are dissolved in a solvent, and a 7% by mass solid content solution and a 5% solid content solution are prepared for each, and filtered through a 0.1 μm polyethylene filter to form a positive resist. A composition was prepared. The prepared positive resist composition was evaluated by the following method, and the results are shown in Table 1 below.

[Image performance test]
(Exposure condition (1))
This condition is for forming a resist pattern under normal exposure conditions (exposure without immersion liquid).
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. A positive resist composition (solid content concentration 7% by mass) prepared thereon was applied, and baked at 130 ° C. for 60 seconds to form a 150 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, the film was heated at 120 ° C. for 90 seconds, developed with an aqueous tetramethylammonium hydroxide solution (2.38 mass%) for 30 seconds, rinsed with pure water, and spin-dried to obtain a resist pattern.

(Exposure condition (2))
This condition is to form a resist pattern by an immersion exposure method using pure water as the immersion liquid.
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. A positive resist composition (solid content concentration 7% by mass) prepared thereon was applied, and baked at 130 ° C. for 60 seconds to form a 150 nm resist film. The obtained wafer was subjected to pattern exposure using an ArF excimer laser immersion scanner (NA 0.75). As the immersion liquid, ultrapure water having impurities of 5 ppb or less was used. Thereafter, heating was performed at 120 ° 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 (3))
This condition is to form a resist pattern by a two-beam interference immersion exposure method using a fluorine compound solution as the immersion liquid.
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. A positive resist composition (solid content concentration 7% by mass) prepared thereon was applied, and baked at 130 ° C. for 60 seconds to form a 150 nm resist film. Further, a water-soluble antireflection film AQUATAR-VI (manufactured by AZ-EM) was applied on the resist film, and baked at 115 ° C. for 60 seconds to form a 35 nm protective film. The obtained wafer was subjected to pattern exposure using a two-beam interference exposure apparatus. Perfluoro (2-butylteteorahydrofuran) was used as the immersion liquid. Thereafter, heating was performed at 120 ° 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.
Moreover, the solid content concentration of the resist composition to be applied was changed to 5.0% by mass and the film thickness was changed to 100 nm, and evaluation was performed in the same manner as described above (thin film exposure).

[Profile]
The profile of the obtained pattern was observed and evaluated with a scanning electron microscope (S-9260, manufactured by Hitachi, Ltd.).

[Line edge roughness]
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 smaller value indicates better performance.

[Etching evaluation]
The prepared positive resist composition (solid content concentration 7%) was applied onto a silicon wafer, and baked at 130 ° C. for 60 seconds to form a 150 nm resist film. The etching rate of CF ₄ / O ₂ (8/2) gas with respect to the obtained resist film was measured using a reactive ion etching apparatus (CSE-1110) manufactured by ULVAC.

The symbols in Table 1 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

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 SL-3: γ-butyrolactone SL-4: Propylene glycol monomethyl ether SL-5: Propylene carbonate

  From Table 1, it is apparent that the positive resist composition of the present invention has improved resist pattern edge roughness and dry etching resistance during immersion exposure.

Claims (8)

(A) A resin having a repeating unit represented by the following general formula (A1) and a repeating unit represented by the following general formula (A2), which increases solubility in an alkali developer by the action of an acid, and (B) A positive resist composition for immersion exposure, comprising a compound that generates an acid upon irradiation with actinic rays or radiation.

In general formula (A1),
X and Y each independently represent a methylene group, an ethylene group, an oxygen atom or a sulfur atom.
R ₁ and R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, a cyano group or a hydroxyl group.
R ₂ and R ₃ are each independently a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, a cyano group, a hydroxyl group, a group having a lactone ring, —COOH, —COOR _5a , —C (═O) —Xa -A'-R < _6a >, -OR < _7a >, -COR < _8a > or an acid-decomposable group is shown.
R _5a represents an alkyl group, a cycloalkyl group, or a group having a lactone ring.
Xa 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 _6a represents —COOH, —COOR _5a , —CN, a hydroxyl group, an alkyl group, an alkoxy group, —CO—NH—R _9a , —CO—NH—SO ₂ —R _9a or a group having a lactone ring.
R _7a and R _8a represent a hydrogen atom, an alkyl group, a cycloalkyl group or a group having a lactone ring.
R _9a represents an alkyl group or a cycloalkyl group.
At least two of R _{1 to} R ₄ may form a divalent linking group to form a ring.
n is 0 or 1.
In general formula (A2),
R ₅ represents an alkyl group, a cycloalkyl group or a group having a lactone ring. The positive resist composition for immersion exposure according to claim 1, wherein R ₅ in the general formula (A2) is a group having a lactone ring. 3. The positive resist composition for immersion exposure according to claim 1, wherein R ₅ in the general formula (A2) is a group having a cyclic hydrocarbon structure.   The positive resist for immersion exposure according to any one of claims 1 to 3, wherein the total solid concentration in the positive resist composition for immersion exposure is 2.0 to 6.0% by mass. Composition.   A pattern forming method comprising the steps of: forming a resist film from the positive resist composition for immersion exposure according to any one of claims 1 to 4; and exposing and developing the resist film.   6. The pattern forming method according to claim 5, wherein immersion exposure is performed through a medium having a refractive index of 1.5 or more.   The pattern forming method according to claim 5, wherein the resist film has a thickness of 30 to 100 nm.   The pattern forming method according to claim 5, wherein a protective film is formed on the resist film.