JP2002062655A - Crosslinkable positive type resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical amplification type crosslinkable positive type resist composition having high resolution, excellent in etching resistance and capable of forming a resist pattern adaptable to a recent tendency to form a thinner film. SOLUTION: In the crosslinkable positive type resist composition containing (A) a resin having alkali solubility increased by the action of an acid and (B) a compound which generates the acid when irradiated with radiation, the component (A) is a copolymer containing a constitutional unit of formula (a1) (where R is H or methyl), a constitutional unit of formula (a2) (where R is H or methyl), a constitutional unit of formula (a3) (where R1 is H or methyl; R2 is lower alkyl; and (m) is an integer of 3-7) and a crosslinking type constitutional unit of formula (a4) (where R1 is H or methyl; R3 and R4 are each lower alkyl; (n) is an integer of 1-3; and A is a single bond or a (n+1)-valent organic group).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified cross-linked positive resist composition capable of forming a resist pattern having high resolution and excellent etching resistance.

[0002]

2. Description of the Related Art Recently, by using a chemically amplified positive resist in combination with an organic or inorganic lower antireflection film, it is possible to obtain a resist having a resistance of 0.1%.
A resolution of about 15 to 0.22 μm has been achieved, and a lithography process that requires such a fine resist pattern has been put into practical use and has already been partially mass-produced.

[0003] On the other hand, the need for miniaturization of semiconductor elements has been increasing more and more, and the use of a KrF excimer laser for 0.12
Development of a next-generation process that requires a fine pattern of about 0.15 μm is in progress. In such a lithography process aiming at high resolution, a thinner resist film (0.6 μm or less) is required, but the resist pattern formed by the thinner film has a problem of poor etching resistance. Newly arises.

Heretofore, a so-called cross-link type chemically amplified positive resist in which a polymer or copolymer containing a hydroxystyrene unit is used as a base resin component and its hydroxyl group is crosslinked between base resins by divinyl ether or the like. It is known (JP-A-6-148889, JP-A-8-305025). However, such a cross-link type chemically amplified positive resist generally has higher etching resistance than a conventional resist, but has a problem in resolution and etching resistance when the resist film is thinned. At present, it is not possible to respond sufficiently.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a chemical compound capable of forming a resist pattern capable of forming a high-resolution and excellent etching resistance and capable of coping with recent thinning. The object of the present invention is to provide an amplified cross-linked positive resist composition.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on a chemically amplified cross-linked positive resist composition, and have found that a resin comprising a copolymer containing a specific structural unit is used. The present inventors have found that a high resolution, excellent etching resistance, and a pattern giving a pattern that meets the needs of thinning can be obtained, and the present invention has been accomplished based on this finding.

That is, the present invention relates to a resist composition comprising (A) a resin whose solubility in alkali is increased by the action of an acid and (B) a compound which generates an acid upon irradiation with radiation. The component is represented by (a ₁ )

Embedded image (Wherein R is a hydrogen atom or a methyl group), (a ₂ ) a general formula

Embedded image (Wherein R has the same meaning as described above), (a ₃ ) a general formula

Embedded image Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a lower alkyl group, m is an integer of 3 to 7, and (a ₄ ) a general formula

Embedded image (Wherein R ¹ has the same meaning as described above, R ³ and R ⁴ are lower alkyl groups, n is an integer of 1 to 3, A is a single bond or n +
A monovalent organic group), and optionally (C) a tertiary aliphatic amine or (D) an organic carboxylic acid or phosphorus oxo acid or An object of the present invention is to provide a crosslinked positive resist composition containing a derivative or both of the components (C) and (D).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the cross-linked positive resist composition of the present invention, a resin having an increased solubility in alkali due to the action of an acid as the component (A) is represented by the general formula (a ₁ )

Embedded image (R in the formula has the same meaning as described above), (a ₂ ) a general formula

Embedded image (Wherein R has the same meaning as described above), (a ₃ ) a general formula

Embedded image Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a lower alkyl group, m is an integer of 3 to 7, and (a ₄ ) a general formula

Embedded image (Wherein R ¹ has the same meaning as described above, R ³ and R ⁴ are lower alkyl groups, n is an integer of 1 to 3, A is a single bond or n +
It is necessary to use a copolymer having a cross-linkable structural unit represented by the following formula (which is a monovalent organic group) as an essential structural unit.

The resin of component (A) is provided with alkali solubility and etching resistance by the structural unit (a ₁ ), and alkali insolubility and etching resistance by the structural unit (a ₂ ). The structural unit (a ₃ ) is a unit having an acid dissociable, dissolution inhibiting group. The tertiary alkyl group is eliminated by the action of an acid generated by exposure, and the ester moiety is changed to a carboxyl group. Therefore, the resin of component (A) was alkali-insoluble before exposure, but plays a role of changing to alkali-soluble after exposure. The unexposed part of this is a monocycloalkyl group in which two alkyl groups of the tertiary alkyl group are bonded, that is, a cyclic group,
It has better etching resistance and a greater contrast difference than conventional chain-like tertiary alkyl groups such as tert-butyl groups. This monocycloalkyl group is a cyclobutyl group,
A cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group are preferred, but a cyclopentyl group and a cyclohexyl group are particularly preferred in terms of high resolution and excellent depth of focus. As the lower alkyl group represented by R ² in the structural unit (a ₃ ), an alkyl group having 2 or more carbon atoms such as an ethyl group and a propyl group is preferable in terms of excellent acid dissociation.

Next, at least two structural units (a ₄ )
Acrylic acid or methacrylic acid tertiary alkyl ester is a cross-linkable unit linked via an organic group to one alkyl group bonded to each tertiary carbon atom, As in the case of the structural unit (a ₃ ), the ester group is changed to a carboxyl group by the action of the acid, and the copolymer in the exposed area is alkali-soluble. On the other hand, in the unexposed area, the copolymer remains alkali-insoluble because the crosslinking group remains. For this reason,
The resist pattern formed in the alkali developing solution has a large difference in contrast and has excellent etching resistance.

R ³ and R ⁴ in the structural unit (a ₄ )
Examples of the lower alkyl group include a methyl group, an ethyl group,
Examples thereof include n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and n-pentyl. A is a single bond or (n + 1)
Organic group having one bond, preferably 1-20 carbon atoms
Is a hydrocarbon group. Examples of the hydrocarbon group when n is 1 include a linear or branched alkylene group, a cycloalkylene group and an arylene group, and examples of the hydrocarbon group when n is 2 include One of the hydrogen atoms in the alkylene, cycloalkylene or arylene group
Examples of the hydrocarbon group when n is 3 include a trivalent group from which two hydrogen atoms have been eliminated, and a hydrocarbon group when two hydrogen atoms in the above alkylene group, cycloalkylene group or arylene group have been eliminated. Valent groups can each be mentioned. Particularly preferred structural units (a ₄ ) are those in which A is a linear alkylene group having 2 to 10 and R ³ and R ⁴ are methyl groups.

Such a cross-linkable structural unit (a ₄ ) is, for example, acrylic acid or methacrylic acid or a reactive functional derivative thereof, for example, a tertiary carbon having two to four molecules of an acid halide having a hydroxyl group bonded to each terminal. Diesters, triesters or tetraesters having 2 to 4 ethylenically unsaturated bonds obtained by bonding to one molecule of alcohols having 2 to 4 hydroxyl groups such as diols, triols or tetrols having atoms Derived from

The above diols include, for example, 2,
3-dimethyl-2,3-butanediol, 2,3-diethyl-2,3-butanediol, 2,3-di-n-propyl-2,3-butanediol, 2,4-dimethyl-
2,4-pentanediol, 2,4-diethyl-2,4
-Pentanediol, 2,4-di-n-propyl-2,
4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 2,5-diethyl-2,5-hexanediol, 2,5-di-n-propyl-2,5-hexanediol, 2, 6-dimethyl-2,6-heptanediol, 2,6-diethyl-2,6-heptanediol,
Glycols such as 2,6-di-n-propyl-2,6-heptanediol, and triols such as 2,4-dimethyl-2,4-dihydroxy-3- (2
-Hydroxypropyl) pentane, 2,4-diethyl-
2,4-dihydroxy-3- (2-hydroxypropyl) pentane, 2,5-dimethyl-2,5-dihydroxy-3- (2-hydroxypropyl) hexane, 2,5
Triols such as -diethyl-2,5-dihydroxy-3- (2-hydroxypropyl) hexane and tetrols include erythritol, pentaerythritol,
Tetrals such as 2,3,4,5-hexanetetrol can be exemplified.

Particularly preferred among these diesters or triesters are those of the general formula

Embedded image (Wherein R ¹ has the same meaning as described above, and p is 0, 1 or 2);

Embedded image Or general formula

Embedded image (Wherein R ¹ has the same meaning as described above).

In the component (A) of the present invention, since the amount of dissolution in alkali is a factor that determines the main resist characteristics such as the resolution of the resist pattern and the shape of the resist pattern, 2.38% by mass of tetrahydrofuran is used. The film weight loss at 23 ° C. with respect to an aqueous solution of methyl ammonium hydroxide is 5 to 500 nm / sec, particularly 10 to 300 nm.
It is preferable to prepare so as to be in the range of nm / sec.

The content ratio of each structural unit used as the component (A) is not particularly limited, but the structural unit (a ₁ ) is 50 to 80 mol%, preferably 65 to 80 mol%, and the structural unit ( a ₂ ) is 1 to 25 mol%, preferably 5 to 20 mol%, and the structural unit (a ₃ ) is 3 to 25 mol%.
Preferably 5 to 20 mol%, and the structural unit (a ₄ ) is 1
To 15 mol%, preferably 3 to 10 mol%. In addition to the structural units (a ₁ ) to (a ₄ ),
If desired, in a range that does not impair the effects of the present invention,
Various structural units that have been proposed as an acrylic acid derivative or methacrylic acid derivative unit of a positive resist for KrF or ArF can be included.

In the cross-linked positive resist composition of the present invention, as the compound (B), which is a compound capable of generating an acid upon irradiation with radiation (hereinafter referred to as an acid generator), a compound of the chemical amplification type has conventionally been used. The acid generator may be appropriately selected from known acid generators used in photoresists, and particularly preferred is an onium salt of a fluoroalkylsulfonic acid ion having 1 to 10 carbon atoms.

Examples of such onium salts include trifluoromethanesulfonate or nonafluorobutanesulfonate of diphenyliodonium, bis (4-te
rt-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate or nonafluorobutanesulfonate In particular, trifluoromethanesulfonate or nonafluorobutanesulfonate of diphenyliodonium or bis (4-tert-butylphenyl) iodonium is preferred.

In the present invention, the acid generator (B) may be used alone or in combination of two or more. The compounding amount is usually selected in the range of 1 to 10 parts by mass with respect to 100 parts by mass of the component (A). If this acid generator is less than 1 part by mass, it is difficult to form an image,
When the amount exceeds 10 parts by mass, a uniform solution is not obtained, and storage stability is reduced.

In the composition of the present invention, if necessary, a tertiary aliphatic amine may be used as the component (C) in order to improve the storage stability over time from exposure to heat treatment after exposure, the resist pattern shape and the resolution. Can be contained.
Examples of this tertiary aliphatic amine include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tri-isobutylamine, tri-tert-butylamine,
Examples include tripentylamine, triethanolamine, and tributanolamine. Of these, triethanolamine is particularly preferred.

These tertiary aliphatic amines may be used alone or in combination of two or more. In addition, the compounding amount is usually 0.01 to 1 to 100 parts by mass of the component (A) from the viewpoints of the stability with time from the exposure to the heat treatment after the exposure, the resist pattern shape and the resolution. It is selected in the range of 0 parts by mass.

Further, in the composition of the present invention, (C)
In order to prevent sensitivity degradation due to the addition of components, eliminate dependency on various substrates, and obtain a good resist pattern,
If necessary, as the component (D), an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof, or a derivative thereof (C)
Both the component and the component (D) can be contained.

The organic carboxylic acids include saturated or unsaturated aliphatic carboxylic acids, alicyclic carboxylic acids, oxycarboxylic acids, alkoxycarboxylic acids, ketocarboxylic acids, aromatic carboxylic acids such as p-hydroxybenzoic acid and o-carboxylic acid. Hydroxybenzoic acid, 2,5-dihydroxybenzoic acid,
Examples include 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2-vinylbenzoic acid, 4-vinylbenzoic acid, phthalic acid, terephthalic acid, and isophthalic acid. Of these, salicylic acid is particularly preferred.

Examples of the oxo acid of phosphorus or a derivative thereof include phosphoric acid such as phosphoric acid, di-n-butyl phosphate and diphenyl phosphate, or a derivative such as an ester thereof, phosphonic acid, Phosphonic acids such as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, dibenzyl phosphonate, and derivatives thereof such as esters, phosphinic acid,
Derivatives such as phosphinic acids such as phenylphosphinic acid and their esters. Among these,
Particularly, phenylphosphonic acid is preferred.

The amount of the component (D) is usually selected in the range of 0.01 to 1.0 part by mass based on 100 parts by mass of the component (A). If the amount is less than 0.01 part by mass, the effect of preventing tailing or tapering will not be sufficiently exhibited, and if it exceeds 1.0 part by mass, the resist pattern will be reduced in film thickness. In order to effectively prevent skirting, taper shape, and film reduction of the resist pattern, this (D)
The preferred amount of the components is in the range of 0.1 to 0.5 parts by mass.

The crosslinked positive resist composition of the present invention comprises
Upon use, it is preferable to use the above components in the form of a solution in which the components are dissolved in a solvent. Examples of the solvent used in this case include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, Dipropylene glycol or polyhydric alcohols such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate and derivatives thereof, cyclic ethers such as dioxane, and methyl lactate , Ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate Le,
Esters such as ethyl ethoxypropionate can be mentioned. These may be used alone or as a mixture of two or more.

The composition of the present invention may further contain additives that are optionally miscible, such as additional resins, plasticizers, stabilizers, colorants, and surfactants for improving the performance of the resist film. Can be added and contained.

As a method of using the composition of the present invention, a conventional method of forming a resist pattern by a photoresist technique is used. However, in order to carry out the method preferably, first, on a support such as a silicon wafer or, if necessary, an organic system is used. Alternatively, on a support provided with an inorganic anti-reflection film, a solution of the resist composition is applied by a spinner or the like, and prebaked to form a photosensitive layer, and a KrF excimer laser beam is applied thereto by, for example, a KrF exposure apparatus. After performing image formation exposure by irradiating through a desired mask pattern, heat treatment is performed. The 1-alkylcyclohexyl group in the component (A) used in the present invention is a protective group that is less likely to be removed by an acid than an acetal group or a tert-butoxycarbonyloxy group. The treatment temperature is preferably 130 ° C. or higher, particularly 140 ° C. or higher.

Next, this is added to a developing solution, for example, 0.1 to 10
Development processing is performed using an alkaline aqueous solution such as a mass% aqueous solution of tetramethylammonium hydroxide. With this forming method, a pattern faithful to the mask pattern can be obtained. The crosslinked positive resist composition of the present invention is also suitable as a positive resist for electron beams.

[0030]

According to the present invention, there is provided a chemically amplified crosslinked positive resist composition capable of forming a resist pattern having high resolution and excellent etching resistance.

[0031]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (A) 63.0 mol% of hydroxystyrene units, 10.5 mol% of styrene units, 23.0 mol% of 1-ethylcyclohexyl acrylate and 2,5-dimethyl-2,5-
100 parts by mass of a copolymer having a weight average molecular weight of 25,000 and a diacrylate of hexanediol of 3.5 mol% (amount dissolved at 23 ° C. in a 2.38 mass% aqueous solution of tetramethylammonium hydroxide at 80 ° C./sec)
(B) 3 parts by mass of diphenyliodonium trifluoromethanesulfonate, (C) triethanolamine 0.1
6 parts by mass and 0.16 parts by mass of (D) phenylphosphonic acid are dissolved in 500 parts by mass of ethyl lactate.
After adding 0.1 parts by mass of a silicone-based surfactant [trade name “R-08” (manufactured by Dainippon Ink and Chemicals, Inc.)] to the total amount, the mixture was filtered through a membrane filter having a pore size of 0.2 μm to obtain a positive resist. A solution was obtained.

On the other hand, an antireflection film forming agent [trade name “AR”
3 "(manufactured by Shipley)], the above-mentioned positive resist solution was spin-coated on a silicon wafer having an anti-reflection film having a thickness of 60 nm,
By pre-baking at 90 ° C. for 90 seconds, a film thickness of 0.45
A μm resist layer was formed.

Then, a reduction projection exposure apparatus NSRS-203B (manufactured by Nikon Corporation, NA =
0.68), selectively irradiating with a KrF excimer laser, heat-treating at 140 ° C. for 90 seconds, and then paddle developing with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide at 23 ° C. for 60 seconds. Was post-baked at 100 ° C. for 60 seconds to obtain a positive resist pattern.

In this way, a good shape of 0.13 μm
An m-hole pattern was obtained. The depth of focus at which a hole pattern of 0.13 μm was obtained was 0.5 μm.
Furthermore, when a mixed gas of CF ₄ , CHF ₃ and helium was used as an etching gas, the film loss per unit time when etching was 7.5 nm / sec.

Example 2 In Example 1, the component (A) was replaced with 70.0 mol% of a hydroxystyrene unit, 15.0 mol% of a styrene unit and 1-
10.0 mol% of ethylcyclohexyl acrylate and 2,5-dimethyl-2,5-dihydroxy-3- (2-
4. hydroxypropyl) hexane triacrylate
0 mol% of a copolymer having a weight average molecular weight of 25,000 (dissolution amount at 23 ° C. in 2.38 mass% aqueous solution of tetramethylammonium hydroxide at 100 ° C. /
Second) A positive resist solution was prepared in the same manner as in Example 1 except that the amount was changed to 100 parts by mass, and then the same resist patterning as in Example 1 was performed. In this way,
A 0.13 μm hole pattern having a good shape was obtained. The depth of focus at which a hole pattern of 0.13 μm was obtained was 0.4 μm. Furthermore, when the film loss per unit time was determined in the same manner as in Example 1, it was found that 7.0 nm /
Seconds.

Example 3 A positive resist solution was prepared in the same manner as in Example 1 except that the component (B) was changed to 4.5 parts by mass of diphenyliodonium nonafluoromethanesulfonate. The same resist patterning as in Example 1 was performed. Thus, a good shape of 0.13 μm
A hole pattern was obtained. The depth of focus at which a hole pattern of 0.13 μm was obtained was 0.4 μm. Further, when the film loss per unit time was determined in the same manner as in Example 1, it was 7.5 nm / sec.

COMPARATIVE EXAMPLE 1 In Example 1, the component (A) was replaced with 65.0 mol% of hydroxystyrene units, 20.0 mol% of styrene units and 1-
A copolymer having a weight average molecular weight of 12,000 and consisting of 15.0 mol% of ethylcyclohexyl acrylate (2.38)
A positive resist solution was prepared in the same manner as in Example 1, except that the amount was changed to 100 parts by mass (dissolution amount at 23 ° C. at 80 ° C./sec in a tetramethylammonium hydroxide aqueous solution at 23 ° C.). Resist patterning was performed. Thus, a slightly tapered 0.16 μm hole pattern was obtained. Also, 0.16
0.4μ depth of focus to obtain μm hole pattern
m. Further, when the film loss per unit time was determined in the same manner as in Example 1, it was 8.0 nm / sec.

COMPARATIVE EXAMPLE 2 In Example 1, the component (A) was replaced with 70.0 mol% of hydroxystyrene units, 15.0 mol% of styrene units, and te.
10 mol% of rt-butyl acrylate and diacrylate of 2,5-dimethyl-2,5-hexanediol 5.0
% Of a copolymer having a weight average molecular weight of 25,000 (dissolution amount at 23 ° C. in 2.38 mass% aqueous solution of tetramethylammonium hydroxide at 80 ° C./sec) 1
A positive resist solution was prepared in the same manner as in Example 1 except that the amount was changed to 00 parts by mass, and then the same resist patterning as in Example 1 was performed. In this way, a well-shaped 0.15 μm hole pattern was obtained, but it was at the limit. The depth of focus at which a hole pattern of 0.15 μm was obtained was 0.4 μm. Further, the film loss per unit time was determined in the same manner as in Example 1.
2.0 nm / sec.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 25/18 C08L 25/18 G03F 7/004 501 G03F 7/004 501 H01L 21/027 (C08F 212/14 // (C08F 212/14 212: 12 212: 12 220: 18 220: 18 220: 20) 220: 20) H01L 21/30 502R (72) Inventor Tomotaka Yamada 150 Nakamaruko, Nakahara-ku, Kawasaki-shi, Kanagawa Tokyo Oka Kogyo Co., Ltd. (72) Inventor Juichi Takayama 150 Nakamurako, Nakahara-ku, Kawasaki-shi, Kanagawa F-term within Tokyo Oka Kogyo Co., Ltd. 4J002 BC071 BC121 DH028 EB116 EF098 EF118 EN027 EN107 EW048 EW128 EW138 GP03 4J100 AB02Q AB07P AL08R AL62S AL63S BA03P BC03R BC04R CA06 JA38

Claims (8)

[Claims] 1. A resist composition comprising (A) a resin whose solubility in alkali is increased by the action of an acid and (B) a compound capable of generating an acid upon irradiation with radiation, wherein the component (A) comprises (A) a ₁ ) General formula (Wherein R is a hydrogen atom or a methyl group), (a ₂ ) a general formula: (Wherein R has the same meaning as described above), (a ₃ ) a general formula: Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a lower alkyl group, m is an integer of 3 to 7, and (a ₄ ) a general formula: (Wherein R ¹ has the same meaning as described above, R ³ and R ⁴ are lower alkyl groups, n is an integer of 1 to 3, A is a single bond or n +
A cross-linked positive resist composition comprising a cross-linkable structural unit represented by the following formula: 2. R ² in the structural unit (a ₃ ) has 2 to 4 carbon atoms.
2. The crosslinked positive resist composition according to claim 1, which is a lower alkyl group. 3. In the structural unit (a ₄ ), n is 1, and A
Is a linear or branched alkylene group having 1 to 20 carbon atoms or a partially or wholly cyclized alkylene group, the crosslinked positive resist composition according to claim 1 or 2. 4. n in the structural unit (a ₄ ) is 1, and A
Is a linear alkylene group having 2 to 10 carbon atoms, and R ³ and R ⁴ are methyl groups. 5. The composition according to claim 5, wherein the component (A) is composed of 50 to 50 structural units (a ₁ ).
80 mol%, structural unit (a ₂ ) 1 to 25 mol%, structural unit (a ₃ ) 3 to 25 mol%, and structural unit (a ₄ ) 1 to 15
The crosslinked positive resist composition according to any one of claims 1 to 4, which is a copolymer comprising mol%. 6. The cross-linking according to claim 1, wherein the component (A) has a film loss of 5 to 500 nm / sec with respect to a 2.38 mass% aqueous solution of tetramethylammonium hydroxide. Positive resist composition. 7. A tertiary aliphatic amine (C) or an oxo acid of phosphorus (D) or an organic carboxylic acid or a derivative thereof, or both of the components (C) and (D), ) 0.01 to 100 parts by mass of the component
The crosslinked positive resist composition according to any one of claims 1 to 6, which is contained in an amount of 1.0 part by mass. 8. The crosslinked positive resist composition according to claim 7, wherein the component (D) is salicylic acid or phenylphosphonic acid.