JP2000275843A - Chemically amplifiable positive resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the chemically amplified positive resist composition enhanced in adhesiveness to a substrate and dry etching resistance and improved in sensitivity and resolution. SOLUTION: The chemically amplified positive resist composition contains a polymer having 2-hydroxyethyl methacrylate polymerization units and polymerization units each having an acid-instable group, and itself being insoluble or hardly soluble in alkali but solubilizable in alkali, when the above acid-instable groups are cleft, and an acid generating agent. This polymer may have other units of monomer, such as 3-hydroxy-1-adamantyl (meth)acrylate, α-(meth) acryloyloxy-γ-butyrolactone (this lactone being optionally substituted by alkyl group) or maleic anhydride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified positive resist composition used for fine processing of semiconductors.

[0002]

2. Description of the Related Art A lithography process using a resist composition is usually employed for fine processing of a semiconductor.
In lithography, the shorter the exposure wavelength, the higher the resolution in principle, as expressed by the Rayleigh diffraction limit equation. Exposure light sources for lithography used in the manufacture of semiconductors have become shorter each year, such as g-line with a wavelength of 436 nm, i-line with a wavelength of 365 nm, and a KrF excimer laser with a wavelength of 248 nm. The ArF excimer laser is considered to be promising, and such an ArF excimer laser exposure resist is being put to practical use in part.

Since the life of a lens used in an ArF excimer laser exposure machine is shorter than that of a lens for a conventional exposure light source, it is desirable that exposure time to an ArF excimer laser beam be as short as possible. For this purpose, since it is necessary to increase the sensitivity of the resist, a so-called chemically amplified resist containing a resin having a group that is cleaved by the acid utilizing the catalytic action of an acid generated by exposure is used.

The resin used for the resist for ArF excimer laser exposure does not have an aromatic ring in order to secure the transmittance of the resist, and has an alicyclic ring instead of the aromatic ring in order to have dry etching resistance. Things are known to be good. Until now, such a resin
DC Hofer, Journal of Photopolymer Science andTec
Various resins are known as described in hnology, Vol. 9, No. 3, 387-398 (1996). However, conventionally known resins have a problem in that when the polarity is insufficient, development peeling is likely to occur due to insufficient adhesiveness during development.

[0005] S. Takechi et al, Journal of Photopoly
mer Science and Technology, Vol.9, No.3, 475-487
(1996) and JP-A-9-73173 disclose methacrylic acid 2
When a polymer or copolymer of -methyl-2-adamantyl is used as a resin for a chemically amplified resist, 2-methyl-2-adamantyl is cleaved by the action of an acid to act positively, It is reported that high dry etching resistance, high resolution and good adhesion to a substrate are obtained. Japanese Patent Application Laid-Open No. 10-274852 discloses that the use of a resin having a butyrolactone residue in a part of a polymerized unit as a resin constituting a chemically amplified resist composition improves the adhesiveness to a substrate. Have been reported.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have previously described (Meth) as a resin for a chemically amplified positive resist composition.
It has been found that by using a polymer having a polymerized unit of 2-alkyl-2-adamantyl acrylate and a polymerized unit of maleic anhydride, the adhesion to a substrate is improved,
A patent application has been filed as Japanese Patent Application No. Hei 10-191559. In addition, by using a resin having a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate and a polymerized unit of 3-hydroxy-1-adamantyl methacrylate, adhesion to a substrate is also improved. Heading,
A patent application has been filed as Japanese Patent Application No. 10-240143. Therefore,
A resin having a γ-butyrolactone residue disclosed in the above-mentioned JP-A-10-274852 or a resin having an adamantane-based polymerized unit disclosed in the above-mentioned Japanese Patent Application No. 10-191559 or Japanese Patent Application No. 10-240143. As a result of further research based on the chemically amplified positive resist composition used, it was found that a resin with a certain type of highly polymerized unit was effective in improving the adhesiveness to the substrate, as well as sensitivity and resolution. In particular, the present inventors have found that the present invention is effective in improving the sensitivity, and completed the present invention.

Accordingly, an object of the present invention is to provide a chemically amplified positive resist composition containing a resin component and an acid generator, which is suitable for excimer laser lithography such as ArF or KrF. An object of the present invention is to provide a substrate having excellent dry etching resistance and improved sensitivity and resolution.

[0008]

That is, the present invention has a polymerized unit of 2-hydroxyethyl methacrylate and a polymerized unit having an acid-labile group, and is itself insoluble or hardly soluble in alkali. Another object of the present invention is to provide a chemically amplified positive resist composition containing a resin which becomes alkali-soluble after the acid-labile group is cleaved by the action of an acid, and an acid generator.

The term "polymerized unit of 2-hydroxyethyl methacrylate" as used herein means a unit formed by opening a double bond of a methacrylic acid portion in 2-hydroxyethyl methacrylate. I).

[0010]

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The resin constituting the resist composition of the present invention has a polymerized unit of 2-hydroxyethyl methacrylate represented by the above formula (I), and the unit is a hydroxyl group which is a polar substituent. The presence of the compound ensures the adhesion to the substrate and contributes to the improvement of the resolution of the resist and the improvement of the dry etching resistance.

By performing polymerization using 2-hydroxyethyl methacrylate as one monomer, the above-mentioned formula (I)
A resin having a polymerized unit of 2-hydroxyethyl methacrylate represented by formula (1) is obtained, but the resin specified in the present invention has a polymerized unit having an acid-labile group together with the polymerized unit. Resins for chemically amplified positive resists are generally insoluble or poorly soluble in alkali by themselves,
Some groups are cleaved by the action of an acid and become alkali-soluble after the cleaving, and the acid-labile groups in the present invention are also various conventionally known ones. be able to. Specific examples of the acid-labile group include various esters of carboxylic acids, for example, alkyl esters represented by tert-butyl ester, methoxymethyl ester, ethoxymethyl ester, 1-ethoxyethyl ester, 1-isobutoxyethyl. Ester, 1-isopropoxyethyl ester, 1-ethoxypropyl ester, 1- (2-methoxyethoxy) ethyl ester, 1
-(2-acetoxyethoxy) ethyl ester, 1-
Acetal-type esters such as [2- (1-adamantyloxy) ethoxy] ethyl ester, 1- [2- (1-adamantancarbonyloxy) ethoxy] ethyl ester, tetrahydro-2-furyl ester and tetrahydro-2-pyranyl ester And alicyclic esters such as isobornyl ester and 2-alkyl-2-adamantyl ester. Monomers that lead to polymerized units having such carboxylic acid esters include (meth) acrylates such as methacrylic acid esters and acrylic acid esters.
It may be an acrylic one or a carboxylic acid ester group bonded to an alicyclic monomer such as norbornene carboxylic acid ester, tricyclodecene carboxylic acid ester or tetracyclodecene carboxylic acid ester.

Among these polymer units having an acid-labile group, in combination with a polymer unit of 2-hydroxyethyl methacrylate, an alicyclic ester of acrylic acid or methacrylic acid, especially (meth) acrylic acid 2-alkyl-2
-Polymerized units of adamantyl are preferred. This polymerized unit is formed by opening the double bond of the (meth) acrylic acid moiety in 2-alkyl-2-adamantyl acrylate or 2-alkyl-2-adamantyl methacrylate. It can be represented by the formula (II).

[0014]

[0015] In the formula, R ¹ represents hydrogen or methyl, R ²
Represents alkyl.

(Meth) acrylic acid 2 of the formula (II)
The polymerized unit of -alkyl-2-adamantyl is also advantageously employed because it contributes to an improvement in dry etching resistance of the resist and an improvement in resolution. In the formula (II), R
^The alkyl represented by ² can have, for example, about 1 to 6 carbon atoms, and is usually advantageously linear, but may be branched when it has 3 or more carbon atoms. Specific R ²
As methyl, ethyl, propyl, isopropyl,
Butyl and the like. Among them, those in which R ³ is methyl or ethyl are advantageous for improving the adhesion between the resist and the substrate and improving the resolution, and those in which ethyl is particularly advantageous. The 2-alkyl-2-adamantyl (meth) acrylates leading to the units of the formula (II) are usually prepared by reacting 2-alkyl-2-adamantanol or a metal salt thereof with an acrylic acid halide or a methacrylic acid halide. it can.

The resin having a polymerized unit of 2-hydroxyethyl methacrylate and a polymerized unit having an acid-labile group used in the present invention comprises 2-hydroxyethyl methacrylate and a monomer having an acid-labile group. It can be produced by performing copolymerization as an essential monomer. When the polymerized unit having an acid-labile group is a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (II), the monomer having an acid-labile group is 2-alkyl-2-adamantyl acrylate or 2-alkyl-2-adamantyl methacrylate may be used.

The resin may have other polymerized units if necessary. For example, a polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate or α- (meth) in which a lactone ring may be substituted with alkyl
It is effective to have polymerized units of acryloyloxy-γ-butyrolactone, polymerized units of maleic anhydride, and the like. 3-hydroxy-1 (meth) acrylate
The term “polymerized unit of adamantyl” means a unit formed by opening a double bond of a (meth) acrylic acid portion in 3-hydroxy-1-adamantyl acrylate or 3-hydroxy-1-adamantyl methacrylate, and is a lactone. The polymerized unit of α- (meth) acryloyloxy-γ-butyrolactone, in which the ring may be substituted with alkyl, refers to unsubstituted or α- (meth) acryloyloxy-γ-butyrolactone in which the lactone ring is substituted with alkyl. The unit formed by opening the double bond of the (meth) acrylic acid portion means the polymerized unit of maleic anhydride means the unit formed by opening the double bond of maleic anhydride,
They can be represented by the following formulas (III) to (V), respectively.

[0019]

In the formulas (III) and (IV), R ³ represents hydrogen or methyl, and R ⁴ , R ⁵ and R ⁶ independently represent hydrogen or alkyl.

(Meth) acrylic acid 3 represented by the formula (III)
-Hydroxy-1-adamantyl polymerized unit, formula (IV)
The polymerized unit of α- (meth) acryloyloxy-γ-butyrolactone and the polymerized unit of maleic anhydride represented by the formula (V) each have a high polarity, and when any of them is present in the resin, Since the adhesiveness of the resist containing the same to the substrate is improved, the combination with the polymerized unit of 2-hydroxyethyl methacrylate more effectively contributes to the improvement of the adhesiveness of the resist to the substrate. Further, the polymerized unit of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula (IV) also contributes to an improvement in resist resolution.

In the formula (IV), R ⁴ , R ⁵ and R ⁶ are each hydrogen or alkyl, and the alkyl has 1 carbon atom.
About 6 to about 6. When the number of carbon atoms is 3 or more, it may be linear or branched. Specific examples of the alkyl represented by R ⁴ , R ⁵ and R ⁶ include methyl, ethyl, propyl, butyl and the like. Examples of a monomer for leading to a polymerized unit of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula (IV) include, for example, α-
Acryloyloxy-γ-butyrolactone, α-methacryloyloxy-γ-butyrolactone, α-acryloyloxy-β, β-dimethyl-γ-butyrolactone, α-methacryloyloxy-β, β-dimethyl-γ-butyrolactone, α-acryloyloxy- α-methyl-γ-butyrolactone, α-methacryloyloxy-α-methyl-γ-butyrolactone, and the like.

In addition to the polymerized units of 2-hydroxyethyl methacrylate and the polymerized units having an acid-labile group, a compound of the formula (I)
II) 3-Hydroxy-1 (meth) acrylate
A polymerized unit of adamantyl, α- represented by the formula (IV)
When a polymerization unit of (meth) acryloyloxy-γ-butyrolactone and / or a polymerization unit of maleic anhydride represented by the formula (V) is present, 2-hydroxyethyl methacrylate and a monomer having an acid-labile group ( For example,
(2-alkyl-2-adamantyl (meth) acrylate)
In addition, 3-hydroxy-1-adamantyl (meth) acrylate, α- (meth) acryloyloxy-γ-butyrolactone whose lactone ring may be substituted with alkyl and / or maleic anhydride may be copolymerized. Further, together with or separately from the polymer units of the formula (III), the formula (IV) and / or the formula (V), other polymer units such as free polymer units may be used as long as the effects of the present invention are not impaired. It may contain a polymerized unit having a carboxylic acid group.

The resin used in the present invention varies depending on the kind of radiation for patterning exposure, the kind of an acid-labile group, and the like. It is preferable to contain it in the range of mol%.
Then, as at least a part of the polymerized unit having an acid-labile group, (meth) acrylic acid 2-
When a polymerized unit of alkyl-2-adamantyl is employed, the polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate is advantageously at least 20 mol% of the whole resin.

The polymerization unit of 2-hydroxyethyl methacrylate is preferably present in the resin in a range of 10 mol% to 70 mol%, more preferably 20 mol% or more.
More preferably, it is present in an amount of 50 mol% or less. Accordingly, when a binary resin of a polymerized unit of 2-hydroxyethyl methacrylate and a polymerized unit having an acid-labile group is used, 2-hydroxyethyl methacrylate is used in an amount of 20 to 70.
It is advantageous to use monomers having acid labile groups in the range of 30 to 80 mol% in the range of mol%, and to copolymerize both.

On the other hand, polymerized units of 3-hydroxy-1-adamantyl (meth) acrylate represented by the formula (III) and α- (meth) acryloyloxy-γ- represented by the formula (IV)
When a polymerized unit of butyrolactone and / or a polymerized unit of maleic anhydride represented by the formula (V) are present, the total thereof should be at least 5 mol%, especially at least 10 mol% in the resin. preferable. Polymerized units of these 3-hydroxy-1-adamantyl (meth) acrylates, α
The polymerization unit of (meth) acryloyloxy-γ-butyrolactone and / or the polymerization unit of maleic anhydride can be present in the resin up to a total of about 50 mol%.

Thus, for example, in addition to polymerized units of 2-hydroxyethyl methacrylate and polymerized units having an acid-labile group, 3- (meth) acrylic acid represented by formula (III)
Ternary or higher having polymerized units of hydroxy-1-adamantyl, polymerized units of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula (IV) and / or polymerized units of maleic anhydride represented by the formula (V) When the copolymer of the formula (1) is used, 10 mol% or more of 2-hydroxyethyl methacrylate is an unsubstituted or lactone ring for leading to 3-hydroxy-1-adamantyl (meth) acrylate, a unit of the formula (IV). Is at least 5 mol% of a second monomer selected from α- (meth) acryloyloxy-γ-butyrolactone and maleic anhydride substituted with alkyl, and a total of 20% of these 2-hydroxyethyl methacrylate and the second monomer is used.
It is advantageous to copolymerize a monomer mixture containing .about.70 mol% and 30-80 mol% of monomers having acid labile groups.

The acid generator, which is another component, is added to the substance itself or to a resist composition containing the substance.
When a radiation such as light or an electron beam is applied, the substance is decomposed to generate an acid. The acid generated from the acid generator acts on the resin to cleave the acid-labile groups present in the resin. Such acid generators include, for example, onium salt compounds, organic halogen compounds, sulfone compounds, sulfonate compounds and the like. Specifically, the following compounds can be mentioned.

Diphenyliodonium trifluoromethanesulfonate, 4-methoxyphenylphenyliodonium hexafluoroantimonate, 4-methoxyphenylphenyliodonium trifluoromethanesulfonate, bis (4-tert-butylphenyl) iodonium tetrafluoroborate, bis (4-tert
-Butylphenyl) iodonium hexafluorophosphate, bis (4-tert-butylphenyl) iodonium hexafluoroantimonate, bis (4-tert
-Butylphenyl) iodonium trifluoromethanesulfonate,

Triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium trifluoromethanesulfonate, 4-methoxyphenyldiphenylsulfonium hexafluoroantimonate, 4-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methylphenyl Diphenylsulfonium trifluoromethanesulfonate, 2,4,6-trimethylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-tert-
Butylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-phenylthiophenyldiphenylsulfonium hexafluorophosphate, 4-
Phenylthiophenyldiphenylsulfonium hexafluoroantimonate, 1- (2-naphthoylmethyl) thiolanium hexafluoroantimonate,
1- (2-naphthoylmethyl) thiolanium trifluoromethanesulfonate, 4-hydroxy-1-naphthyldimethylsulfonium hexafluoroantimonate, 4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate,

2-methyl-4,6-bis (trichloromethyl) -1,3,5-triazine, 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2-
Phenyl-4,6-bis (trichloromethyl) -1,3,
5-triazine, 2- (4-chlorophenyl) -4,6
-Bis (trichloromethyl) -1,3,5-triazine, 2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine, 2- (4
-Methoxy-1-naphthyl) -4,6-bis (trichloromethyl) -1,3,5-triazine, 2- (benzo [d] [1,3] dioxolan-5-yl) -4,6-
Bis (trichloromethyl) -1,3,5-triazine,
2- (4-methoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine, 2- (3
4,5-trimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine, 2- (3
4-dimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine, 2- (2,4-dimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5 -Triazine, 2- (2-methoxystyryl) -4,6-bis (trichloromethyl) -1,3,
5-triazine, 2- (4-butoxystyryl) -4,
6-bis (trichloromethyl) -1,3,5-triazine, 2- (4-pentyloxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,

1-benzoyl-1-phenylmethyl p
-Toluenesulfonate (commonly called benzoin tosylate), 2-benzoyl-2-hydroxy-2-phenylethyl p-toluenesulfonate (commonly called α-methylol benzoin tosylate), 1,2,3-benzenetriyl trismethanesulfonate, , 6-Dinitrobenzyl p-toluenesulfonate, 2-nitrobenzyl p-toluenesulfonate, 4-nitrobenzyl
p-toluenesulfonate,

Diphenyl disulfone, di-p-tolyl disulfone, bis (phenylsulfonyl) diazomethane, bis (4-chlorophenylsulfonyl) diazomethane, bis (4-methylphenylsulfonyl) diazomethane, bis (4-tert-butylphenylsulfonyl) diazomethane , Bis (2,4-xylylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, (benzoyl) (phenylsulfonyl) diazomethane,

N- (phenylsulfonyloxy) succinimide, N- (trifluoromethylsulfonyloxy) succinimide, N- (trifluoromethylsulfonyloxy) phthalimide, N- (trifluoromethylsulfonyloxy) -5-norbornene-2, 3-dicarboximide, N- (trifluoromethylsulfonyloxy) naphthalimide, N- (10-camphorsulfonyloxy) naphthalimide and the like.

In general, in a chemically amplified positive resist composition, a basic compound, particularly a basic nitrogen-containing organic compound, for example, an amine is added as a quencher to thereby form an acid accompanying the withdrawal after exposure. It is known that the deterioration of performance due to deactivation can be improved. In the present invention, it is preferable to blend such a basic compound. Specific examples of the basic compound used for the quencher include those represented by the following formulas.

[0036]

In the formula, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ independently represent hydrogen, alkyl, cycloalkyl, aryl or alkoxy which may be substituted by a hydroxyl group, and A represents alkylene; Represents carbonyl or imino. Here, the alkyl and alkoxy represented by R ^{11 to} R ¹⁵ can have about 1 to 6 carbon atoms, the cycloalkyl can have about 5 to 10 carbon atoms, and the aryl has The number can be on the order of 6-10. Further, the alkylene represented by A can have about 1 to 6 carbon atoms, and may be linear or branched.

The resist composition of the present invention preferably contains the resin in the range of 80 to 99.9% by weight and the acid generator in the range of 0.1 to 20% by weight based on the total solid content. Also, when using a basic compound as a quencher, similarly based on the total solid content of the resist composition,
The content is preferably in the range of 0.0001 to 0.5% by weight. The composition may also contain small amounts of various additives such as sensitizers, dissolution inhibitors, other resins, surfactants, stabilizers, and dyes, if necessary.

The resist composition of the present invention is usually used as a resist solution in a state where the above-mentioned components are dissolved in a solvent, and is applied on a substrate such as a silicon wafer by a conventional method such as spin coating. The solvent used here may be any as long as it dissolves each component, has an appropriate drying rate, and gives a uniform and smooth coating film after the solvent evaporates. A solvent generally used in this field is used. Can. For example,
Glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate and propylene glycol monomethyl ether acetate, esters such as ethyl lactate, butyl acetate, amyl acetate and ethyl pyruvate, acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone And cyclic esters such as γ-butyrolactone. These solvents can be used alone or in combination of two or more.

The resist film applied on the substrate and dried is subjected to an exposure treatment for patterning, and then subjected to a heat treatment for accelerating a deprotection group reaction, and then developed with an alkali developing solution. You. The alkaline developer used here can be various alkaline aqueous solutions used in this field, but generally, aqueous solutions of tetramethylammonium hydroxide and (2-hydroxyethyl) trimethylammonium hydroxide (commonly known as choline) are used. Often used.

[0041]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Parts in the examples are by weight unless otherwise specified. The weight average molecular weight is a value determined by gel permeation chromatography using polystyrene as a standard.

Synthesis Example 1 of Monomer (Synthesis of 2-ethyl-2-adamantyl methacrylate) To 31.1 g of 2-adamantanone was added 50 ml of diethyl ether.
g of ethyllithium, while maintaining the temperature of the solution not to exceed 10 ° C.
200 ml of a diethyl ether solution containing 4 mol / L was added dropwise. After stirring at 0 ° C. for 2 hours, methacrylic acid chloride 2 was maintained while maintaining the temperature at not higher than 10 ° C.
6.2 g (1.2 mol times based on 2-adamantanone) was added dropwise. After the addition, the mixture was stirred at room temperature for 12 hours. Thereafter, the precipitated inorganic salt was separated by filtration, and the organic layer was washed with a 5% by weight aqueous solution of sodium bicarbonate, and then washed twice with water.
After concentrating the organic layer, the residue was distilled under reduced pressure to obtain 2-ethyl-2-adamantyl methacrylate represented by the following formula.

[0043]

Monomer Synthesis Example 2 (Synthesis of α-methacryloyloxy-γ-butyrolactone) 100 g of α-bromo-γ-butyrolactone and 104.4 g of methacrylic acid (2.0 mol times based on α-bromo-γ-butyrolactone) ) Was added, and methylisobutyl ketone (3 times by weight of α-bromo-γ-butyrolactone) was added to obtain a solution. There, 183.6 g of triethylamine (α
-3.0 mol times bromo-γ-butyrolactone)
Was added dropwise, followed by stirring at room temperature for about 10 hours. After filtration, the organic layer was washed with a 5% by weight aqueous sodium bicarbonate solution, and then washed twice with water. The organic layer was concentrated to obtain α-methacryloyloxy-γ-butyrolactone represented by the following formula.

[0045]

Resin Synthesis Example 1 (Synthesis of Resin A) 2-Ethyl-2-adamantyl methacrylate, 3-hydroxy-1-adamantyl methacrylate and 2-hydroxyethyl methacrylate were used in a molar ratio of 5: 2.5: 2.5. Charged at a ratio (20.0 g: 9.5 g: 5.2 g), methyl isobutyl ketone was added at twice the weight of all monomers to form a solution. Azobisisobutyronitrile was added as an initiator thereto in an amount of 2 mol% based on the total amount of the monomers, and was added at 85 ° C. for about
Heated for hours. Thereafter, an operation of pouring the reaction solution into a large amount of heptane to precipitate was performed three times, and purification was performed. As a result, a copolymer having a weight average molecular weight of about 15,000 was obtained. This copolymer has units represented by the following formula, and is referred to as resin A.

[0047]

Resin Synthesis Example 2 (Synthesis of Resin X: Comparative) 2-Ethyl-2-adamantyl methacrylate, 3-hydroxy-1-adamantyl methacrylate, and α-methacryloyloxy-γ-butyrolactone, 2.5:
It was charged at a molar ratio of 2.5 (20.0 g: 9.5 g: 7.3 g), and methylisobutyl ketone, which was twice the weight of all monomers, was added to form a solution. Azobisisobutyronitrile was added as an initiator thereto in an amount of 2 mol% based on the total amount of monomers,
Heated at 80 ° C. for about 8 hours. Thereafter, an operation of pouring the reaction solution into a large amount of heptane to precipitate was performed three times, and purification was performed.
As a result, a copolymer having a weight average molecular weight of about 9,200 was obtained. This copolymer has units represented by the following formula, and is referred to as a resin X.

[0049]

Examples and Comparative Examples Using Resin A and Resin X obtained in Resin Synthesis Examples 1 and 2, each was mixed with each component according to the following composition, and further filtered through a fluororesin filter having a pore size of 0.2 μm. Thus, a resist solution was prepared.

Resin 10 parts Acid generator: 4-methylphenyldiphenylsulfonium trifluoromethanesulfonate 0.2 part (“MDS-205” manufactured by Midori Kagaku Co., Ltd.) Quencher: 2,6-diisopropylfluoroaniline 0.015 part Solvent: propylene glycol monomethyl 47.5 parts of ether acetate 2.5 parts of γ-butylolactone

A silicon wafer treated with hexamethyldisilazane at 23 ° C. for 20 seconds (water contact angle 50
°), the thickness of the resist solution prepared above after drying was 0.
Spin coating was performed to a thickness of 5 μm. Prebaking after the application of the resist solution was performed on a direct hot plate at 120 ° C. for 60 seconds.

An ArF excimer exposure machine [“NSR-Ar” manufactured by Nikon Corporation]
F ”, NA = 0.55], and the line-and-space pattern was exposed by changing the exposure stepwise. The line-and-space pattern was exposed by using a reticle (mask) for a dark field pattern and a reticle (mask) for a bright field pattern. The reticle of the dark field pattern referred to here is a glass surface only in the space portion of the resist pattern and a chrome surface in all other portions. Provides a pattern in which the entire periphery of the line and space pattern remains as a resist layer.The reticle of the bright field pattern is a chrome surface on the outer frame, and a resist pattern based on the glass surface inside the frame. The line area is patterned with a chrome layer, so After the development, the resist layer around the line-and-space pattern is removed, and a resist layer corresponding to the outer frame is left outside the pattern, after exposure, on a hot plate at 115 ° C. for 60 seconds. Was subjected to a post-exposure bake (PEB), followed by paddle development with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide for 60 seconds.The pattern after development was observed with a scanning electron microscope, and the following method was used. , Effective sensitivity and resolution were examined, and the results are shown in Table 1.

Effective sensitivity: The exposure was such that a 0.18 μm line and space pattern was 1: 1.

Resolution: The minimum size of the line and space pattern separated by the exposure amount of the effective sensitivity was displayed.

[0056]

[Table 1]

Further, when the pattern after exposure and development with the above-described effective sensitivity using a reticle of a bright field pattern was observed, the resist in the outer frame portion remained in accordance with the reticle pattern in both the examples and the comparative examples. And showed good adhesiveness. In the case of a resist having poor adhesion, the resist in the outer frame portion is peeled off and chipped.

As described above, the resist using the resin A according to the present invention does not cause development peeling, has excellent adhesiveness to a substrate, and has good resolution and sensitivity. And it is much faster. The compositions used in the examples give similarly excellent resist patterns even when exposed with a KrF excimer laser exposure machine.

[0059]

Industrial Applicability The chemically amplified positive resist composition of the present invention is excellent in adhesion to a substrate, sensitivity and resolution.
Also, various performances such as dry etching resistance are good.
Therefore, this composition can be used for a KrF excimer laser or A
Suitable for exposure using rF excimer laser, etc.
Thereby, a high-performance resist pattern is provided.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kaoru Araki 3-1-198 Kasuganaka, Konohana-ku, Osaka Sumitomo Chemical Co., Ltd. F-term (reference) 2H025 AA01 AA02 AA09 AA14 AB16 AC04 AC08 AD03 BE00 BG00 CB14 CB41 CB52 CC20

Claims (6)

[Claims] (1) It has a polymerized unit of 2-hydroxyethyl methacrylate and a polymerized unit having an acid-labile group, and is itself insoluble or hardly soluble in alkali, but is insoluble in the above acid by the action of an acid. A chemically amplified positive resist composition comprising a resin which becomes alkali-soluble after a stable group is cleaved, and an acid generator. 2. The composition according to claim 1, wherein the polymerized unit having an acid-labile group contains a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate. 3. The resin according to claim 1, wherein said resin is obtained by copolymerizing a monomer mixture containing 20 to 70 mol% of 2-hydroxyethyl methacrylate and 30 to 80 mol% of a monomer having an acid-labile group. 2. The composition according to 2. 4. The resin further comprises (meth) acrylic acid 3-
3. The composition according to claim 1, further comprising a polymerized unit of a monomer selected from hydroxy-1-adamantyl, α- (meth) acryloyloxy-γ-butyrolactone, and a lactone ring which may be substituted with alkyl, and maleic anhydride. 4. 5. The resin according to claim 1, wherein said resin comprises 2-hydroxyethyl methacrylate in an amount of at least 10 mol%, 3-hydroxy-1-adamantyl (meth) acrylate, and an α- (meth) acrylate in which the lactone ring may be substituted with alkyl. Acryloyloxy-γ-
5 mol% or more of a second monomer selected from butyrolactone and maleic anhydride, 20 to 70 mol% of 2-hydroxyethyl methacrylate and the second monomer in total, and 30 to 30 mol% of a monomer having an acid-labile group. 5. The composition according to claim 4, which is obtained by copolymerization of a monomer mixture containing 80 mol%. 6. The composition according to claim 1, further comprising an amine as a quencher.