JP2000275845A - Chemically amplifying positive resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. which has small dependence on substrates when the compsn. is applied on a basic substrate or low reflection substrate and which can form a good profile for any substrate by incorporating a specified resin and a specified acid producing agent. SOLUTION: This compsn. contains a resin having a 2-alkyl-2-adamantyl (meth)acrylate polymer unit expressed by formula I which itself is insoluble or hardly soluble with an alkali but changes into soluble with the alkali by the effect of an acid, and a sulfonium salt-based acid producing agent expressed by formula II. In formula I, R1 is hydrogen or a methyl group and R2 is an alkyl group. In formula II, each of Q1 to Q3 is independently hydrogen atom, a hydroxy group, 1-6C alkyl group or 1-6C alkoxy group and (n) is an integer 4 to 8. The resin to constitute the resist compsn. to be used may consist of only 2-alkyl-2-adamantyl (meth)acrylate polymer unit, however, it is usually advantageous that the resin consists of a copolymer having other polymer units.

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. ArF excimer laser is promising.

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, J. Photopolym. Sci. Technol., Vol. 9,
Various resins as described in No. 3, 387-398 (1996) are known. However, in a conventionally known resin,
In particular, when the polarity is insufficient, there is a problem that development peeling is likely to occur due to insufficient adhesiveness during development.

[0005] S. Takechi et al, J. Photopolym. Sci.
Technol., Vol. 9, No. 3, 475-487 (1996) and Japanese Patent Application Laid-Open No. 9-73.
No. 173 discloses that when a polymer or copolymer of 2-methyl-2-adamantyl methacrylate is used as a resin for a chemically amplified resist, the 2-methyl-2-adamantyl group is decomposed by the action of an acid. It has been reported that the film can be cracked to act positively, and that high dry etching resistance, high resolution and good adhesion to a substrate be obtained. Also,
JP-A-10-274852 discloses that, as a resin constituting a chemically amplified positive resist composition, a resin having a butyrolactone residue in a part of a polymerized unit is used to improve adhesiveness to a substrate. It has been reported. Further, JP-A-10-319595 describes a resist composition using a resin having a γ-butyrolactone-3-yl residue as a carboxyl-protecting group.

On the other hand, since the chemically amplified resist utilizes the action of an acid, when the substrate is basic,
There is a problem that the acid is deactivated and the profile becomes a skirted shape. It is known that this problem can be solved by adding a large amount of a basic quencher substance. However, when such a large amount of quencher substance is added, the sensitivity decreases. Furthermore, in ArF excimer laser exposure, a resist is often applied on a substrate having low reflectance such as an organic or inorganic antireflection film. The use of such a low-reflection substrate is effective in improving the dimensional uniformity, but generally, the profile of the resist becomes tapered due to light absorption and deteriorates. As described above, the chemically amplified resist has a problem that the performance, particularly the profile, changes depending on the type of the substrate.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a chemically amplified positive resist composition containing a resin component and an acid generator and suitable for excimer laser lithography such as ArF or KrF. It has good resist performance, such as high resolution, resolution, and adhesion to the substrate, and has a low substrate dependence even when applied to a basic substrate or a low-reflection substrate, giving a good profile to any substrate. Is to provide.

[0008] Japanese Patent Application No. 11-2385 related to the earlier application of the present applicant
No. 42 reports that a resin having a certain kind of highly polar polymerized unit together with an adamantane-based polymerized unit having a specific structure is effective for improving the adhesion to a substrate. The present inventors have disclosed a resin having a butyrolactone residue disclosed in JP-A-10-274852 and JP-A-10-319595, and an adamantane-based polymerization disclosed in Japanese Patent Application No. 11-238542. As a result of further study on a system using a resin having units as a chemically amplified positive resist composition, the resolution of these compositions was improved by using an acid generator having a specific structure as an acid generator. The present invention has been found to be improved, and the profile of a basic substrate or a low-reflection substrate has also been improved, and the present invention has been completed.

[0009]

That is, the present invention provides the following formula (I)

[0010]

Wherein R ¹ represents hydrogen or methyl;
R ² represents alkyl), which has a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate, which itself is insoluble or hardly soluble in alkali, but is soluble in alkali by the action of an acid. And the following formula (V)

[0012]

(Wherein Q ¹ , Q ² and Q ³ independently represent hydrogen, a hydroxyl group, alkyl having 1 to 6 carbons or alkoxy having 1 to 6 carbons, and n is an integer of 4 to 8) Represent)
And a chemically amplified positive resist composition comprising an acid generator represented by the formula:

The polymerization unit of the 2-alkyl-2-adamantyl (meth) acrylate represented by the above formula (I) is the same as the (meth) in 2-alkyl-2-adamantyl acrylate or 2-alkyl-2-adamantyl methacrylate. ) A unit formed by opening the double bond of the acrylic acid moiety. The resin constituting the resist composition of the present invention may be composed of only the polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate, but is usually a copolymer containing other polymerized units. Is advantageous.

The polymerized unit other than 2-alkyl-2-adamantyl (meth) acrylate preferably employed in the case of forming a copolymer is represented by the following formula (II):

[0016]

(Wherein R ³ represents hydrogen or methyl), a polymerized unit of 3-hydroxy-1-adamantyl (meth) acrylate represented by the following formula (III):

[0018]

(Wherein R ⁴ represents hydrogen or methyl;
⁵ , R ⁶ and R ⁷ each independently represent hydrogen or alkyl), α- (meth) acryloyloxy-γ-
Butyrolactone polymerization unit, the following formula (IV)

[0020]

(Wherein R ⁴ , R ⁵ , R ⁶ and R ⁷ are as defined above), and a polymerization unit of β- (meth) acryloyloxy-γ-butyrolactone. Of these, (meth) acrylic acid 3
The polymerization unit of -hydroxy-1-adamantyl is a unit formed by opening a double bond of a (meth) acrylic acid moiety in 3-hydroxy-1-adamantyl acrylate or 3-hydroxy-1-adamantyl methacrylate. Polymerized units of α- (meth) acryloyloxy-γ-butyrolactone and β- (meth) acryloyloxy-
The polymerization unit of γ-butyrolactone is α-acryloyloxy-γ-butyrolactone, α-methacryloyloxy-γ in which the lactone ring may be substituted with alkyl.
-Butyrolactone, β-acryloyloxy-γ-butyrolactone or β-methacryloyloxy-γ-butyrolactone is a unit formed by opening the double bond of the (meth) acrylic acid moiety.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The resin constituting the resist composition of the present invention has a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the above formula (I), and may optionally have a polymerized unit. A polymerized unit of 3-hydroxy-1-adamantyl (meth) acrylate represented by the formula (II), a polymerized unit of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula (III), It may have a polymerized unit of β- (meth) acryloyloxy-γ-butyrolactone represented by IV). Therefore, this resin is a 2-alkyl-2- (meth) acrylate.
It can be produced by polymerization or copolymerization using adamantyl as one monomer. When 3-hydroxy-1-adamantyl (meth) acrylate is used as a copolymer component at this time, a copolymer having a unit of the formula (II) together with a unit of the formula (I) can be obtained, and a lactone ring When α- or β- (meth) acryloyloxy-γ-butyrolactone which may be substituted with alkyl is used, a copolymer having a unit of the formula (III) or a unit of the formula (IV) together with a unit of the formula (I) is obtained. can get. Furthermore, for example, (meth) acrylic acid 3-
By using both hydroxy-1-adamantyl and α- (meth) acryloyloxy-γ-butyrolactone in which the lactone ring may be substituted with alkyl, the formula (I):
A terpolymer having units (II) and (III) is obtained. Of course, it is also possible to copolymerize another monomer as described later.

Among these monomers, 2-alkyl-2-adamantyl (meth) acrylate can be usually produced by reacting 2-alkyl-2-adamantanol or a metal salt thereof with acrylic acid halide or methacrylic acid halide. . Although 3-hydroxy-1-adamantyl (meth) acrylate is commercially available, 1,3-dibromoadamantane is hydrolyzed to 1,3-dihydroxyadamantane, which is combined with acrylic acid, methacrylic acid or a halide thereof. It can also be produced by reacting. Α- or β- (meth) acryloyloxy-
γ-butyrolactone is obtained by reacting an acrylic or methacrylic acid with α- or β-bromo-γ-butyrolactone in which the lactone ring may be substituted with alkyl, or α in which the lactone ring may be substituted with alkyl. -Or β-hydroxy-γ-butyrolactone can be produced by reacting acrylic acid halide or methacrylic acid halide.

(Meth) acrylic acid 2 represented by the formula (I)
The polymerization unit of -alkyl-2-adamantyl secures the transmittance of the resist and contributes to the improvement of dry etching resistance due to the presence of the adamantane ring which is an alicyclic ring. Furthermore, since the 2-alkyl-2-adamantyl group in this unit is cleaved by the action of an acid, this unit contributes to increasing the alkali solubility of the resist film after exposure. R ² in the formula (I) is an alkyl, and the alkyl can have, for example, about 1 to 8 carbon atoms, and is usually preferably straight-chain. It may be branched. Specific examples of R ² include methyl, ethyl, propyl, isopropyl, and butyl. Among them, those in which R ² is methyl or ethyl, particularly ethyl, are advantageous for improving the adhesion between the resist and the substrate and improving the resolution. Specific examples of the monomer for leading to the polymerization unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (I) include, for example, 2-methyl-2-adamantyl acrylate and 2-ethyl acrylate -2-adamantyl, methacrylic acid 2-
Methyl-2-adamantyl, 2-ethyl methacrylate-
2-adamantyl and the like.

(Meth) acrylic acid 3 represented by the formula (II)
-Hydroxy-1-adamantyl polymerized unit, formula (III)
The polymerized unit of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula and the polymerized unit of β- (meth) acryloyloxy-γ-butyrolactone represented by the formula (IV) are all highly polar. The presence in the resin improves the adhesiveness of the resist containing it to the substrate. These polymerized units also contribute to improving the resolution of the resist. Furthermore, the polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate is
It also contributes to improving the dry etching resistance of the resist.
Further, the polymerization unit of β- (meth) acryloyloxy-γ-butyrolactone also contributes to improving the transmittance of the resist.

(Meth) acrylic acid 3 represented by the formula (II)
Monomers leading to the polymerized units of -hydroxy-1-adamantyl are 3-hydroxy-1-adamantyl acrylate or 3-hydroxy-1-adamantyl methacrylate. In the formulas (III) and (IV), R ⁵ , R ⁶
And R ⁷ are each hydrogen or alkyl, and this alkyl can have about 1 to 6 carbon atoms. When it has 3 or more carbon atoms, it may be linear or branched. R ⁵ , R
Specific examples of the alkyl represented by ⁶ and R ⁷ include methyl, ethyl, propyl, butyl and the like. The formula (I
Examples of the monomer for leading to the polymerized unit of α- (meth) acryloyloxy-γ-butyrolactone represented by II) include 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. Further, as a monomer for leading to a polymerization unit of β- (meth) acryloyloxy-γ-butyrolactone represented by the formula (IV), for example, β-acryloyloxy-γ-butyrolactone, β-methacryloyloxy-γ-butyrolactone, β-methacryloyloxy-α-methyl-γ-butyrolactone and the like.

In general, a resin for a chemically amplified positive resist is itself insoluble or hardly soluble in alkali, but is partially alkali-dissociated by the action of an acid and becomes alkali-soluble after dissociation. In the resin specified in the present invention,
The 2-alkyl-2-adamantyl group in the formula (I) is cleaved by the action of an acid. Accordingly, by having the polymerized unit of the formula (I), the resist composition containing this resin acts positively, but optionally contains a polymerized unit having another group which is cleaved by the action of an acid. May be. Specific examples of other groups that can be cleaved by the action of an acid include various esters of carboxylic acids, for example, methyl esters and tert-
Alkyl ester represented by butyl ester, methoxymethyl ester, ethoxymethyl ester, 1-ethoxyethyl ester, 1-isobutoxyethyl ester, 1-isopropoxyethyl ester, 1-ethoxypropyl ester, 1- (2-methoxyethoxy ester ) Ethyl ester, 1- (2-acetoxyethoxy) ethyl ester, 1- [2- (1-adamantyloxy) ethoxy] ethyl ester, 1- [2- (1-adamantanecarbonyloxy) ethoxy] ethyl ester, tetrahydro- Acetal type esters such as 2-furyl ester and tetrahydro-2-pyranyl ester; alicyclic esters such as isobornyl ester; The monomer leading to the polymerization unit having such a carboxylic acid ester may be an acrylic monomer such as methacrylic acid ester or acrylic acid ester, norbornene carboxylic acid ester, tricyclodecene carboxylic acid ester, tetracyclodecene carboxylic acid Like an ester, a carboxylic acid ester group bonded to an alicyclic monomer may be used.

The resin used in the present invention varies depending on the type of radiation for patterning exposure and the type of a group which can be cleaved by the action of an acid, but generally, a polymerized unit having a group which is cleaved by the action of an acid. Is preferably contained in the range of 30 to 80 mol%. In particular, as a group which is cleaved by the action of an acid, the polymerization unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (I) is preferably at least 20 mol% of the whole resin. It is. Further, in addition to the polymerization unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (I), the polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate represented by the formula (II) And / or α- represented by the formula (III)
When polymerized units of (meth) acryloyloxy-γ-butyrolactone are present, these units of formula (II) and
It is preferable that the unit of (III) is in the range of 20 to 70 mol% of the whole resin. Furthermore, 2-alkyl-2 (meth) acrylate represented by the formula (I)
In the case where a polymerized unit of β- (meth) acryloyloxy-γ-butyrolactone represented by the formula (IV) is present in addition to the polymerized unit of adamantyl, the unit of the formula (IV) is 20 to 70% of the whole resin. It is preferred to be in the range of mol%.

Therefore, the unit of the formula (II) together with the unit of the formula (I)
And / or a copolymer having a unit of the formula (III), the (meth) acrylic acid 2 for leading to the unit of the formula (I)
20-80 mol%, preferably 30-80 mol%, of alkyl-2-adamantyl, and 3-hydroxy-1-adamantyl (meth) acrylate and / or (-) to lead to units of formula (II) Α- (meta) wherein the lactone ring for leading to the unit of III) may be substituted with alkyl
Acryloyloxy-γ-butyrolactone in total of 20 to 7
It is advantageous to copolymerize a monomer mixture containing 0 mol%. Similarly, when the copolymer having the unit of the formula (IV) together with the unit of the formula (I) is used, the 2-alkyl-2-adamantyl (meth) acrylate for leading to the unit of the formula (I) is 20 to 80 mol%, preferably 30-80 mol%,
It is advantageous to copolymerize a monomer mixture containing 20 to 70 mol% of β- (meth) acryloyloxy-γ-butyrolactone in which the lactone ring for leading to the unit of the formula (IV) may be substituted with alkyl. .

Resins having polymerized units of the formula (I) and, optionally, further having polymerized units of the formulas (II), (III) and / or (IV) can be prepared by reacting an acid as described above. In addition to containing polymerized units having other groups that can be cleaved by an action, as long as the effects of the present invention are not impaired, it is also possible to include other polymerized units that are not cleaved by the action of an acid. It is possible. Examples of other polymer units that can be contained include a polymer unit having a free carboxylic acid group, a polymer unit of maleic anhydride, a polymer unit of itaconic anhydride, and (meth)
Examples include acrylonitrile polymerization units.

The acid generator, another component of the resist composition, is decomposed by applying radiation such as light or an electron beam to the substance itself or the resist composition containing the substance. To generate an acid. The acid generated from the acid generator acts on the resin to cleave the group that is cleaved by the action of the acid present in the resin. In the present invention, the sulfonium salt-based compound represented by the formula (V) is used as an acid generator.

In the formula (V), Q ¹ , Q ² and Q ³ are each hydrogen, hydroxyl, alkyl having 1 to 6 carbons or alkoxy having 1 to 6 carbons. In the above case, the chain may be linear or branched. Specific examples of alkyl include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl,
Examples include pentyl and hexyl, and examples of alkoxy include methoxy, ethoxy, propoxy, and butoxy.

In the formula (V), n representing the number of carbon atoms in the alkane moiety constituting the perfluoroalkanesulfonate ion which is an anion is an integer of 4 to 8. Thus, the present invention relates to the above formula (I) The main feature of the present invention is that a sulfonium salt having a perfluoroalkane sulfonate anion having a large number of carbon atoms is used as an acid generator in combination with a resin having a polymerized unit represented by the formula (1). By using such a compound as an acid generator, the resolution of the resist is improved, and the profile on a basic substrate or a low-reflection substrate is also improved. The reason for this is not always clear, but as the anions become bulky, the diffusion distance of the generated acid in the resist is shortened, and the distribution of the acid more faithful to the optical image is achieved. It is presumed that the profile on the low reflection substrate is improved. Further, it is considered that since the diffusion distance of the acid in the resist becomes shorter, the diffusion of the base from the basic substrate is suppressed, and a profile with less footing can be obtained on the basic substrate.

As the sulfonium salt represented by the formula (V), if there is a commercial product, it can be used as it is, or it can be produced according to a conventional method. For example,
Reacting the corresponding triphenylsulfonium bromide with silver perfluoroalkanesulfonate,
According to the description of m. Pharm. Bull., Vol. 29, 3753 (1981), the corresponding diphenyl sulfoxide is reacted with a benzene compound and a perfluoroalkanesulfonic acid in the presence of trifluoroacetic anhydride. , JP-A-8-3110
A method in which a corresponding aryl Grignard reagent is reacted with thionyl chloride, then with a triorganosilyl halide to form a triarylsulfonium halide, and then reacted with silver perfluoroalkanesulfonate according to the description in JP-A-18. Can be manufactured. Further, the compound wherein Q ¹ , Q ² and / or Q ³ in the formula (V) is a hydroxyl group can be prepared according to the description in JP-A-8-311018.
The compound can be produced by treating a triphenylsulfonium salt having a tert-butoxy group on a benzene ring with the same sulfonic acid as the anion of the compound to remove the tert-butyl group.

Specific examples of the sulfonium salt corresponding to the formula (V) include the following compounds.

Triphenylsulfonium perfluorobutanesulfonate, triphenylsulfonium perfluorooctanesulfonate, 4-methylphenyldiphenylsulfonium perfluorobutanesulfonate, 4-methylphenyldiphenylsulfonium perfluorooctanesulfonate, 4-hydroxyphenyldiphenylsulfonium perfluorobutane Sulfonate, 4-hydroxyphenyldiphenylsulfonium perfluorooctanesulfonate, 4-methoxyphenyldiphenylsulfonium perfluorobutanesulfonate, 4-methoxyphenyldiphenylsulfonium perfluorooctanesulfonate, tris (4-methylphenyl) sulfonium perfluorobutanesulfonate, tris ( 4- Butylphenyl) sulfonium perfluorooctane sulfonate, tris (4-methoxyphenyl) sulfonium perfluorobutane sulfonate, tris (4-methoxyphenyl)
Sulfonium perfluorooctanesulfonate and the like.

The resist composition of the present invention comprises the above-mentioned formula (I)
A resin having a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (1), a sulfonium salt having a perfluoroalkanesulfonate anion having a large number of carbon atoms represented by the formula (V) as an acid generator Although it is a combination, other acid generators can be used in combination with this sulfonium salt, if desired.
Other acid generators that can be used in combination include other onium salt compounds such as sulfonium salts and iodonium salts other than the sulfonium salt represented by the formula (I), organic halogen compounds such as haloalkyltriazine compounds, disulfones and diazomethane. Sulfone compounds such as disulfones and various sulfonic acid esters are included.

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.

[0039]

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;
A represents alkylene, carbonyl or imino. Here, the alkyl and alkoxy represented by R ^{11 to} R ¹⁵ are
The cycloalkyl can have about 1 to 6 carbon atoms, the cycloalkyl can have about 5 to 10 carbon atoms, and the aryl can have about 6 to 10 carbon atoms. 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 about 80 to 99.9% by weight of a resin and about 0.1 to 20% by weight of an acid generator, based on the total solid content. preferable. When a basic compound is used as the quencher, the content is preferably in the range of about 0.01 to 1 % by weight based on the total solid content of the resist composition. The composition may also contain, if necessary, sensitizers, dissolution inhibitors, other resins, surfactants, stabilizers, dyes, etc.
Various additives may be contained in small amounts.

The resist composition of the present invention is usually made into a resist solution in which each of the above components is dissolved in a solvent, and is applied onto a substrate such as a silicon wafer. 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 ketones such as 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 to a heat treatment for accelerating the deprotection 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.

[0044]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, percentages and parts representing the content or the used amount are based on 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-methyl-2-adamantyl methacrylate) 83.1 parts of 2-methyl-2-adamantanol and 101 parts of triethylamine were charged into a reaction vessel, and 200 parts of methyl isobutyl ketone was added. To make a solution. 78.4 parts of methacrylic acid chloride (1.5 mol times based on 2-methyl-2-adamantanol) was added dropwise thereto, and the mixture was stirred at room temperature for about 10 hours. 5% organic layer after filtration
It was washed with an aqueous solution of sodium bicarbonate and then twice with water. After the organic layer was concentrated, the residue was distilled under reduced pressure to obtain 2-methyl-2-adamantyl methacrylate represented by the following formula in a yield of 75%.

[0046]

Synthesis Example 2 of Monomer (Synthesis of 2-Ethyl-2-adamantyl methacrylate) 31.1 parts of 2-adamantanone were mixed with 50 parts of diethyl ether.
And adding ethyl lithium to the solution 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 as it is, 26.2 parts of methacrylic acid chloride (1.2 mol times based on 2-adamantanone) while maintaining the temperature at not higher than 10 ° C.
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% aqueous sodium bicarbonate solution, and then washed twice with water. After the organic layer was concentrated, the residue was distilled under reduced pressure to obtain 2-ethyl-2-adamantyl methacrylate represented by the following formula in a yield of 60%.

[0048]

Synthesis Example 3 of Monomer (Synthesis of α-methacryloyloxy-γ-butyrolactone) 100 parts of α-bromo-γ-butyrolactone and 104.4 parts of methacrylic acid (2.0 parts with respect to α-bromo-γ-butyrolactone) (Molar times), and methylisobutylketone was added at 3 times the weight of α-bromo-γ-butyrolactone to form a solution. There triethylamine 183.6
Then, the mixture was added dropwise (3.0 mol times based on α-bromo-γ-butyrolactone), and then stirred at room temperature for about 10 hours.
After filtration, the organic layer was washed with a 5% aqueous sodium bicarbonate solution, and then twice with water. The organic layer was concentrated to obtain α-methacryloyloxy-γ-butyrolactone represented by the following formula in a yield of 85%.

[0050]

Resin Synthesis Example 1 (Synthesis of Resin A) 2-Methyl-2-adamantyl methacrylate and α-methacryloyloxy-γ-butyrolactone in a molar ratio of 5: 5 (15.0 parts: 11.7 parts) , And methylisobutyl ketone was added in an amount 2 times by weight based on all the monomers to form a solution. Thereto, azobisisobutyronitrile as an initiator was added at 2 mol% based on the total amount of monomers, and the mixture was 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 10,000 was obtained. This copolymer has the following structural units, which will be referred to as resin A.

[0052]

Resin Synthesis Example 2 (Synthesis of Resin B) Instead of 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate was used, and α-methacryloyloxy-γ-butyrolactone was used in 5: The same operation as in Resin Synthesis Example 1 was carried out except that the mixture was charged at a molar ratio of 5 (40.0 parts: 29.3 parts). As a result, a copolymer having a weight average molecular weight of about 5,600 was obtained. This copolymer has the following structural units, and is referred to as a resin B.

[0054]

Resin Synthesis Example 3 (Synthesis of Resin C) 2-Ethyl-2-adamantyl methacrylate, 3-hydroxy-1-adamantyl methacrylate and α-methacryloyloxy-γ-butyrolactone were mixed in a ratio of 5: 2.5.
The same operation as in Resin Synthesis Example 1 was carried out except that the mixture was charged at a molar ratio of 2.5 (20.0 parts: 9.5 parts: 7.3 parts). As a result, a copolymer having a weight average molecular weight of about 9,200 was obtained. This copolymer has the following structural units and is referred to as a resin C.

[0056]

Synthesis Example 1 of Acid Generator (Synthesis of triphenylsulfonium perfluorooctanesulfonate) In a four-necked flask, perfluorooctanesulfonic acid 7 was added.
5 parts and 100 parts of water were charged, and 21.4 parts of silver carbonate was added with stirring. After stirring at room temperature for 3 days, the mixture was filtered, and the obtained cake was washed with 10 parts of ion-exchanged water and then with diethyl ether 2 parts.
The residue was washed with 0 parts and dried to obtain 60.3 parts of silver perfluorooctanesulfonate.

A four-necked flask was charged with 0.5 part of triphenylsulfonium bromide and 30 parts of nitromethane, and then charged with 0.9 part of silver perfluorooctanesulfonate obtained above and 30 parts of nitromethane. Stirred for hours. Thereafter, the suspension was filtered, and the filtrate was concentrated to obtain 1.2 parts of triphenylsulfonium perfluorooctanesulfonate.

Synthesis Example 2 of Acid Generator (Synthesis of 4-methylphenyldiphenylsulfonium perfluorooctanesulfonate) A four-necked flask was charged with 8.0 parts of diphenylsulfoxide and 80.0 parts of toluene, and cooled to 2 ° C. Next, 16.6 parts of trifluoroacetic anhydride and 19.8 parts of perfluorooctanesulfonic acid were charged, and 30
Stirred for minutes. After standing, the lower layer was concentrated, and chloroform 3 was added.
Diluted with 40 parts. The obtained chloroform solution was washed six times with 85 parts of ion-exchanged water and then concentrated to obtain 27.7 parts of 4-methylphenyldiphenylsulfonium perfluorooctanesulfonate.

Synthesis Example 3 of Acid Generator (Synthesis of 4-methylphenyldiphenylsulfonium perfluorobutanesulfonate) A four-necked flask was charged with 5.06 parts of diphenylsulfoxide and 50.6 parts of toluene, and cooled to 2 ° C. Next, 10.5 parts of trifluoroacetic anhydride and 7.50 parts of perfluorobutanesulfonic acid were charged, and 60 parts at the same temperature.
Stirred for minutes. After standing, the lower layer was concentrated, and chloroform 1 was added.
Diluted with 00 parts. The obtained chloroform solution was washed 11 times with 50 parts of ion-exchanged water and then concentrated to obtain 12.0 parts of 4-methylphenyldiphenylsulfonium perfluorobutanesulfonate.

Examples 1 to 6 and Comparative Examples 1 to 3 The following acid generators were mixed together with a resin, a quencher and a solvent in the composition shown in Table 1 and the pore size was 0.2.
The solution was filtered through a μm fluororesin filter to prepare a resist solution.

PAG1: Triphenylsulfonium perfluorobutanesulfonate (“TPS-10” manufactured by Midori Kagaku)
9 ”). PAG2: Triphenylsulfonium perfluorooctanesulfonate. PAG3: 4-Methylphenyldiphenylsulfonium
Perfluorooctane sulfonate. PAGX: 4-methylphenyldiphenylsulfonium
Trifluoromethanesulfonate (Midori Chemical's MD
S-205 ").

[0063]

TABLE 1 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Ingredient Examples 1-6 Comparative Examples 1-3 Resin ( (Types are shown in Table 2) 10 parts 10 parts Acid generator (Types are shown in Table 2) * 0.2 part quencher: 2,6-diisopropyl aniline 0.015 part 0.015 parts Solvent: propylene glycol monomethyl ether acetate 47.5 parts 47.5 parts γ-butylolactone 2.5 Part 2.5 parts ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ * The amount of acid generator in Examples 1 to 6 Equimolar to that of Examples 1-3.

The above resist solution was spin-coated on a bare (raw) silicon wafer which had been subjected to a surface treatment at 90 ° C. for 180 seconds using hexamethyldisilazane so that the film thickness after drying was 0.5 μm. . After the application of the resist solution, prebaking was performed on a direct hot plate at a temperature shown in the column of “prebaking” in Table 2 for 60 seconds. An ArF excimer exposure machine (“NSR ArF” manufactured by Nikon Corporation, NA = 0.55) was applied to the wafer on which the resist film was formed in this manner.
The line and space pattern was exposed while changing the exposure amount stepwise. After the exposure, post-exposure baking was performed for 60 seconds on a hot plate at a temperature shown in the column of “PEB” in Table 2, and paddle development was performed for 60 seconds with a 2.38% tetramethylammonium hydroxide aqueous solution. Was. The pattern after development was observed with a scanning electron microscope, and the effective sensitivity and resolution were examined by the following methods. The results are shown in Table 2.

Effective sensitivity: Display was performed with a minimum exposure amount at which a 0.18 μm line and space pattern was 1: 1.

Resolution: Displayed with the minimum size of a line and space pattern separated by the exposure amount of the effective sensitivity.

Further, a resist film was formed on a quartz glass wafer such that the above-mentioned resist solution was applied and pre-baked at 120 ° C. for 60 seconds to have a thickness of 0.5 μm. The transmittance of this resist film at 193 nm was measured with a spectrophotometer, and the results are also shown in Table 2.

[0068]

[Table 2] Example No. Resin Acid generator Free break PEB Effective sensitivity Resolution Transmittance 実 施 Example 1 A PAG1 120 ℃ 120 ℃ 17 mJ / cm ² 0.16 [mu] m 45% 〃 2 B PAG1 80 ℃ 80 ℃ 15 mJ / cm 2 0.15μm 45% 〃 3 B PAG3 80 ℃ 80 ℃ 19 mJ / cm 2 0.15μm 45% 〃 4 C PAG1 120 ℃ 115 ℃ 16 mJ / cm ² 0.16μm 43% ５ 5 C PAG2 120 ℃ 115 ℃ 24 mJ / cm ² 0.16μm 43% ６ 6 C PAG3 120 ℃ 115 ℃ 22 mJ / cm ² 0.16μm 43% ───────── ────────────────────────── Comparative Example 1 A PAGX 120 ° C 120 ° C 18 mJ / cm ² 0.17μm 45% 〃 2B PAGX 80 ° C 80 ℃ 18 mJ / cm ² 0.16μm 45% ３ 3C PAGX 120 ℃ 115 ℃ 20 mJ / cm ² 0.17μm 43% ━━━━━━━━━━━━━━━━━━━━━━ ━━━ ━━━━━━━━━

Further, after a wafer (basic substrate) provided with a silicon nitride film having a thickness of 1,800.degree. Was subjected to a surface treatment under the same conditions as described above, the wafer was subjected to Examples 4 to 6 and Comparative Examples 1 and 3. Each of the resist solutions prepared in step 1 was applied in the same manner as above to form a resist film, which was then patterned. The cross-sectional shape of the obtained pattern was observed with a scanning electron microscope to evaluate the dependence on the substrate. As a result, Example 4
Each of the patterns obtained from the resist liquids of Comparative Examples 1 and 3 had good profiles without any tailing, while the patterns obtained from the resist liquids of Comparative Examples 1 and 3 were:
He had a hem pull shape.

As described above, the resolution of the resist of the example is improved as compared with the resist of the comparative example using 4-methylphenyldiphenylsulfonium trifluoromethanesulfonate (PAGX) having a small number of carbon atoms in the sulfonate anion portion as an acid generator. In addition, the tailing profile on a basic substrate is unlikely to occur. Furthermore, the resists prepared in these examples give good profiles even when applied to low reflection substrates.

Examples 7 to 9 and Comparative Example 4 The following resins C and D and acid generators PAG3, PAG4 and PAGX were mixed together with a quencher and a solvent in the composition shown in Table 3 to obtain a mixture having a pore size of 0.2 μm. The solution was filtered through a fluororesin filter to prepare a resist solution.

Resin C: 2-ethyl-2-adamantyl methacrylate obtained in Resin Synthesis Example 3 and methacrylic acid 3
-Hydroxy-1-adamantyl and α-methacryloyloxy-γ-butyrolactone molar ratio of 50/25/25
A resin having a weight average molecular weight of about 9,200. Resin D: a copolymer of 2-methyl-2-adamantyl methacrylate and β-methacryloyloxy-γ-butyrolactone in a molar ratio of 47.7 / 52.3, having a weight average molecular weight of about 8,400. PAG3: 4-methylphenyldiphenylsulfonium
Perfluorooctane sulfonate. PAG4: 4-methylphenyldiphenylsulfonium
Perfluorobutane sulfonate. PAGX: 4-methylphenyldiphenylsulfonium
Trifluoromethanesulfonate (Midori Chemical's MD
S-205 ").

[0073]

[Table 3] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Component Example 7 Example 8 Example 9 Comparative Example 4 Resin: C 10 parts 10 parts 10 parts D 10 parts Acid generator: PAG3 0.2 parts 0.2 parts PAG4 0.15 parts PAGX 0.1 parts Quencher: 2,6-diisopropyl aniline 0.0075 parts 0.0075 parts 0.0075 parts 0.0075 parts 57 parts 57 parts 57 parts 57 parts γ-butylolactone 3 parts 3 parts 3 parts 3 parts ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━

[0074] "DUV-30" manufactured by Brewer was applied, and 215
The resist solution was spin-coated on a silicon wafer on which an organic antireflection film having a thickness of 1,600 ° was formed by baking at 60 ° C. for 60 seconds so that the film thickness after drying was 0.39 μm. After the application of the resist solution, prebaking was performed on a direct hot plate at a temperature shown in the column of “prebaking” in Table 4 for 60 seconds. The wafer on which the resist film was formed was exposed to a line and space pattern in the same manner as in Example 1. After the exposure, post-exposure baking was performed for 60 seconds on a hot plate at a temperature shown in the column of “PEB” in Table 4, and paddle development was performed for 60 seconds with a 2.38% aqueous solution of tetramethylammonium hydroxide. . The pattern after development was observed with a scanning electron microscope, and the effective sensitivity and resolution were examined in the same manner as in Example 1. The resist solution was applied on a quartz glass wafer, and a resist film was formed so that the film thickness after pre-baking under the same conditions as above was 0.39 μm. Was measured. The results are summarized in Table 4.

[0075]

[Table 4] Example No. Resin Acid generator Free break PEB Effective sensitivity Resolution Transmittance ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 7 C PAG3 130 ℃ 130 ℃ 25 mJ / cm ² 0.14μm 62% ８ 8 C PAG4 130 ℃ 130 ℃ 25 mJ / cm ² 0.14μm 62% ９ 9 D PAG3 130 ℃ 120 ℃ 19 mJ / cm ² 0.14μm 70% ────────── ───────────────────────── Comparative Example 4 C PAGX 120 ℃ 115 ℃ 35 mJ / cm ² 0.15μm 62% ━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Further, a wafer (basic substrate) provided with a silicon nitride film having a thickness of 1,800.degree. Is subjected to a surface treatment using hexamethyldisilazane at 90.degree. C. for 180 seconds. The solution was applied in the same manner as above to form a resist film, and was patterned. The cross-sectional shape of the obtained pattern was observed with a scanning electron microscope to evaluate the dependence on the substrate. As a result, each of the patterns obtained from the resist solutions of Examples 7 to 9 had a favorable profile without any tailing. On the other hand, the pattern obtained from the resist solution of Comparative Example 4 had a skirt shape.

As described above, the resists of Examples 7 to 9 were compared with the resist of Comparative Example 4 in which 4-methylphenyldiphenylsulfonium trifluoromethanesulfonate (PAGX) having a small number of carbon atoms in the sulfonate anion portion was used as the acid generator. Thus, sensitivity and resolution are improved, and a tailing profile on a basic substrate hardly occurs.
In particular, the resist of Example 9 using the resin D is excellent in sensitivity and transmittance.

[0078]

According to the present invention, a resist composition comprising a specific resin and a specific acid generator has a good resolution in ArF excimer laser exposure and the like, and is applicable to a basic substrate or a low-reflection substrate. In this case, a good profile is provided, and there is an effect that substrate dependency is small.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/027 H01L 21/30 502R

Claims (10)

[Claims] (1) The following formula (I) (Wherein, R ¹ represents hydrogen or methyl, and R ² represents alkyl) having a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate, which is insoluble or difficult to dissolve in alkali. A resin which is soluble but soluble in alkali by the action of an acid; (Wherein, Q ¹ , Q ² and Q ³ independently represent hydrogen, a hydroxyl group, alkyl having 1 to 6 carbons or alkoxy having 1 to 6 carbons, and n represents an integer of 4 to 8). A chemically amplified positive resist composition comprising the sulfonium salt-based acid generator shown below. 2. A (meth) acrylic acid 2 represented by the formula (I)
The composition according to claim 1, wherein the polymerized unit of -alkyl-2-adamantyl is selected from polymerized units of 2-methyl-2-adamantyl methacrylate and polymerized units of 2-ethyl-2-adamantyl methacrylate. 3. The resin according to claim 2, wherein (Wherein R ³ represents hydrogen or methyl), a polymerized unit of 3-hydroxy-1-adamantyl (meth) acrylate represented by the following formula (III): (Wherein R ⁴ represents hydrogen or methyl, and R ⁵ , R ⁶ and R ⁷ independently represent hydrogen or alkyl) selected from the polymerization units of α- (meth) acryloyloxy-γ-butyrolactone 3. The method according to claim 1, further comprising:
A composition as described. 4. The resin according to claim 1, wherein the resin is substantially a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (I) and (meth) acrylic acid 3 represented by the formula (II).
The composition according to claim 3, which is a binary copolymer comprising polymerized units of -hydroxy-1-adamantyl. 5. The resin of claim 1, wherein said resin is a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (I) and α- (meth) acryloyloxy-γ represented by the formula (III): The composition according to claim 3, which is a binary copolymer composed of polymerized units of -butyrolactone. 6. The resin according to claim 1, wherein said resin is a polymerized unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (I), and 3- (meth) acrylic acid represented by the formula (II):
Polymerized unit of hydroxy-1-adamantyl and formula (III)
The composition according to claim 3, which is a terpolymer comprising polymerized units of α- (meth) acryloyloxy-γ-butyrolactone represented by the following formula: 7. The resin according to claim 1, wherein said resin has 30 to 80 mol% of 2-alkyl-2-adamantyl (meth) acrylate and 3-hydroxy-1-adamantyl (meth) acrylate and a lactone ring substituted with alkyl. The composition according to any one of claims 3 to 6, which is obtained by copolymerization of a monomer mixture containing 20 to 70 mol% of a monomer selected from α- (meth) acryloyloxy-γ-butyrolactone. 8. The resin according to claim 1, wherein (Wherein R ⁴ represents hydrogen or methyl, and R ⁵ , R ⁶ and R ⁷ independently represent hydrogen or alkyl) having a polymerized unit of β- (meth) acryloyloxy-γ-butyrolactone The composition according to claim 1. 9. The resin comprises 30 to 80 mol% of 2-alkyl-2-adamantyl (meth) acrylate and β- (meth) acryloyloxy-γ-butyrolactone in which the lactone ring may be substituted by alkyl. 20-70 mol%
9. The composition according to claim 8, which is obtained by copolymerization of a monomer mixture containing the composition. 10. The composition according to claim 1, further comprising an amine as a quencher.