JPH08101508A - Resist composition - Google Patents

Abstract

PURPOSE: To provide a resist compsn. excellent in resist characteristics by incorporating a specified polymer and a radiation sensitive component which produces an acid when irradiated with activated radiation. CONSTITUTION: A polymer having structural units represented by formulae I-III and a radiation sensitive component which produces an acid when irradiated with activated radiation are incorporated. In the formulae I-III, each of R<1> -R<3> is H, 1-4C substitutable alkyl, halogen, cyano, etc., R<4> is a group represented by formula IV, etc., R<5> is straight chain, branched or cyclic 1-8C substitutable alkyl, substitutable alkenyl or substitutable aryl, (k), (m) and (n) show the ratio among the units represented by formulae I-III, k+m+n=1, 0<k<0.95, 0<m<0.95, 0.05<=n<=0.6 and 0.1<=k/(k+m)<1. In formula IV, each of R<6> -R<8> is H, straight chain, branched or cyclic 1-8C substitutable alkyl, etc., and R<6> and R<7> may form a ring by bonding to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-sensitive composition, and more specifically, it is useful for ultrafine processing of semiconductor devices using radiation such as deep ultraviolet rays such as excimer laser, charged particles such as X-ray and electron beam. Radiation-sensitive composition suitable as another resist.

[0002]

2. Description of the Related Art When manufacturing a semiconductor device, a resist is applied to the surface of a silicon wafer to form a photosensitive film, which is irradiated with light to form a latent image, which is then developed to form a negative or positive image. The image is obtained by using the lithographic technology. By the way, IC, LSI, and VLSI
Due to the high integration, high density and miniaturization of semiconductors,
A technique for forming a fine pattern of 5 μm or less is required. However, it is extremely difficult to form a fine pattern of 0.5 μm or less with high precision by conventional lithography using near-ultraviolet rays and visible rays, and the yield is significantly reduced. Therefore, in order to increase the resolution of exposure, conventional photolithography that uses near-ultraviolet light having a wavelength of 350 to 450 nm is used, and in order to increase the resolution of exposure, far-ultraviolet light having a short wavelength (short-wavelength ultraviolet light), krypton fluoride laser (KrF excimer laser light). A wavelength of 248 nm) and a lithography technique using an electron beam are being studied.
A conventional novolak resin is used as a base polymer in lithography using near-ultraviolet light. Although the resin has a good transmittance for ultraviolet light having a wavelength of 350 to 450 nm, it has a long wavelength. Since the transmittance is extremely deteriorated with respect to ultraviolet rays and KrF excimer laser light, when the resin is used as the base polymer, sufficient sensitivity cannot be obtained and the pattern shape is poor. Has been. For the purpose of improving the poor transmittance, a chemically amplified resist using a polyvinylphenol derivative as a base polymer has been studied (Japanese Patent Publication No. 2-276).
No. 60), however, the pattern shape has not yet met the requirements. Further, as a recent example, a method using a hydrogenated polyvinylphenol derivative as a base polymer for the purpose of further improving the transmittance (Japanese Patent Laid-Open No. 5-249673, etc.) is known. Although the pattern shape is considerably improved by this improvement, further improvement is required for the more advanced required characteristics of the resist, particularly the resolution.

[0003]

Under the above-mentioned conventional techniques, the inventors of the present invention have conducted diligent research to solve the above-mentioned problems, and as a result, have found that vinylphenol and methacrylate units containing a certain acid labile group have been introduced. In addition, it was found that a resist composition having excellent resist characteristics can be obtained by using a resin having a vinylphenol unit having no acid labile group, and based on this finding, the present invention has been completed.

[0004]

According to the present invention, the general formulas (1), (2) and (3) are thus obtained.

[Chemical 6]

[Chemical 7]

Embedded image (In the formulas (1) to (3), R ^{1 to} R ³ are each independently a hydrogen atom, a substituted alkyl group having 1 to 4 carbon atoms, a halogen atom, a cyano group or a nitro group, and R ⁴ is the following formula. (4) or (5)

[Chemical 9]

[Chemical 10] (In the formulas (4) and (5), R ^{6 to} R ¹³ are each independently a hydrogen atom, a linear, branched, or cyclic C 1-8 substituted alkyl group, a substituted alkenyl group, or a substituted aryl. R ⁶ and R ⁷ , R ¹¹ and R ¹² may be bonded to each other to form a ring), and R ⁵ is a linear, branched or cyclic C 1 to C 8 group. Is a substituted alkyl group, a substituted alkenyl group, or a substituted aryl group. The ratio of the units represented by the formulas (1), (2) and (3) is k,
is represented by m and n, k + m + n = 1, 0 <k <0.95,
0 <m <0.95, 0.05 ≦ n ≦ 0.6, 0.1 ≦ k
/ (K + m) <1. The present invention provides a resist composition comprising a polymer having a structural unit represented by the formula (1) and a radiation-functional component that generates an acid when exposed to activating radiation.

The present invention will be described in detail below. The resin used in the present invention is a polymer having the structural units represented by the above formulas (1) to (3). This polymer may be a block copolymer or a random copolymer.
The lower limit of the weight average molecular weight of this polymer is usually 100
0, preferably 2,000 and the upper limit is usually 100,
000, preferably 20,000. If it deviates from this range, the resolution may decrease. Formula (1)-
Specific examples of R ^{1 to} R ³ in (3) include a hydrogen atom;
An alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, and a t-butyl group, and one or more hydrogen atoms of these alkyl groups Substitutes substituted with halogen atoms, alkoxy groups, etc .; halogen atoms such as fluorine, chlorine, bromine, iodine; cyano groups; nitro groups. R ^{4 in the} formula (1) is a group represented by the formula (4) or (5), and specific examples of R ^{6 to} R ^{13 in} the formulas (4) and (5) include a hydrogen atom and a methyl group. , Ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, hexyl group, 1-ethylbutyl group, 4-methylpentyl group,
Heptyl group, 1-methylpentyl group, 4-methylhexyl group, 3,3-dimethylpentyl group, octyl group, 1-
Ethylhexyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, 2-methoxyethyl group, 2-ethoxyethyl group, chloromethyl group,
2-chloroethyl group, 2-methylcyclopentyl group, 5
-A linear, branched or cyclic C1-C8 alkyl group such as a methoxypentyl group or a 3,3-dichlorocyclooctyl group, or one or more hydrogen atoms of these alkyl groups are substituted with a halogen atom or an alkoxy group. Substituted compounds;
Vinyl group, allyl group, 1-propenyl group, 1-butenyl group, 3-butenyl group, 1-pentynyl group, 2-pentynyl group, 4-pentynyl group, 2-methyl-1-butenyl group, 2-cyclobutenyl group, 3 -Hexenyl group, 2-cyclopentenyl group, 1-methyl-2-cyclopentenyl group,
Substitutable alkenyl groups such as 2-cyclohexenyl group and 3-methyl-2-cyclohexenyl group; substitutable aryl groups such as phenyl group, tolyl group, 4-chlorophenyl group and 2,4-dimethylphenyl group. . Also R
⁶ and R ⁷ , R ¹¹ and R ¹² may be bonded to each other to form a ring such as a cyclopentyl ring, a cyclohexyl ring, a cycloheptyl ring, a cyclopentenyl ring or a cyclohexenyl ring. In the formula (3), R ⁵ is a linear, branched, or cyclic C 1 to C 8 substitutable alkyl group, substitutable alkenyl group, or substitutable aryl group, and specific examples of such a group are the same as above. The following are listed. Preferred substituents for R ⁵ are those in which the carbon to which the oxygen atom is attached has three substituents.

The proportions of the structural units represented by the formulas (1), (2) and (3) are represented by k, m and n, and k + m + n = 1,0.
<K <0.95, 0 <m <0.95, 0.05 ≦ n ≦
0.60.1 ≦ k / (k + m) <1. The lower limit of the ratio (k / (k + m)) of the units represented by the formula (1) among the structural units represented by the formulas (1) and (2) is usually 0.1,
It is preferably 0.2, more preferably 0.4, and the upper limit is usually less than 1, preferably 0.8, more preferably 0.
7 If this ratio is too small, the dissolution inhibiting effect may decrease and the residual film rate may decrease. On the contrary, if it is too large, the adhesiveness may decrease, which is not preferable. Further, the ratio of the total of the structural units represented by the formulas (1) and (2) to the entire resin ((k + m) / (k + m +
n)) is not particularly limited as long as the above conditions are satisfied, but is preferably 0.4 to 0.95, and more preferably 0.60 to 0.85. If this ratio is too low (that is, if the ratio of formula (3) is too high), the etching resistance may decrease, and if this ratio is too high (that is, if the ratio of formula (3) is too low). ) The sensitivity may decrease.

The polymer having the structural units represented by the above formulas (1) to (3) used as the resin component in the present invention is
It is synthesized according to a conventional method. For example, in addition to a method of mixing monomers having a structural unit represented by each formula in a desired ratio and polymerizing, a monomer giving a structural unit of the formula (2) and a structural unit of the formula (3) are mixed. There is also a method of introducing R ⁴ of the formula (1) after polymerizing with a given monomer. A partially hydrogenated product of the obtained polymer can also be used in the present invention.

Specific examples of the monomer giving the structural unit of the above formula (1) include 4- (t-butoxycarbonyloxy) styrene and 3- (t-butoxycarbonyloxy).
Styrene, 2- (t-butoxycarbonyloxy) styrene, 4- (t-butoxycarbonylmethyloxy) styrene, 3- (t-butoxycarbonylmethyloxy)
Styrene, 2- (t-butoxycarbonylmethyloxy) styrene, 4- (t-amyloxycarbonyloxy) styrene, 3- (t-amyloxycarbonyloxy) styrene, 2- (t-amyloxycarbonyloxy) styrene, 4- (t-amyloxycarbonylmethyloxy) styrene, 3- (t-amyloxycarbonylmethyloxy) styrene, 2- (t-amyloxycarbonylmethyloxy) styrene, 4- (s-butoxycarbonyloxy) styrene, 3- (s-butoxycarbonyloxy) styrene, 4- (s-butoxycarbonylmethyloxy) styrene, 4-isopropoxycarbonyloxystyrene, 2-isopropoxycarbonyloxystyrene, 4- (t-butoxycarbonylchloromethyloxy) Stiletto , May be mentioned 4- (4-methoxycarbonyloxy) styrene, 4- (cyclohexyloxy-carbonyloxy) styrene, 4-styrene derivatives and these α- methyl styrene derivatives such as (cyclopentyloxy carbonyloxy) styrene.
Specific examples of the monomer giving the structural unit of the above formula (2) include 4-hydroxystyrene, 3-hydroxystyrene, 2-hydroxystyrene, α-methyl-4-hydroxystyrene, α-methyl-3-hydroxy. styrene,
Examples include α-methyl-2-hydroxystyrene and 4-hydroxy-3-methylstyrene. Formula (3)
Specific examples of the monomer that gives the structural unit of
Methyl acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, t-methacrylate
Examples thereof include (meth) acrylic acid esters such as butyl, t-amyl (meth) acrylate, and cyclohexyl (meth) acrylate.

When R ⁴ of the formula (1) is introduced later, methyl bromoacetate, ethyl bromoacetate, propyl is added to the monomer giving the formula (2).
Bromoacetate, t-butyl bromoacetate, t
-Amyl bromoacetate, t-butyl 4- (bromomethyl) phenoxyacetate, t-amyl 4-
A compound such as (bromomethyl) phenoxyacetate is reacted under basic conditions.

Specific examples of the resin used in the present invention include 4
-(T-Butoxycarbonyloxy) styrene / 4-hydroxystyrene / methyl methacrylate polymer, 4-
(T-Butoxycarbonyloxy) styrene / 4-hydroxystyrene / methyl methacrylate polymer, 4-
(T-Butoxycarbonylmethoxy) styrene / 4-hydroxystyrene / methyl methacrylate polymer, 4-
(T-Butoxycarbonylmethoxy) styrene / 4-hydroxystyrene / t-butyl methacrylate polymer, 4- (s-butoxyoxy) styrene / 4-hydroxystyrene / ethyl methacrylate polymer, 4-
(T-butoxycarbonylchloromethoxy) styrene /
4-hydroxystyrene / t-butyl methacrylate polymer, 4- (isopropoxycarbonyloxy) styrene / 4-hydroxystyrene / t-amyl methacrylate polymer, 4- (cyclohexyloxycarbonyloxy) styrene / 4-hydroxystyrene / t -Amyl methacrylate polymer, 4- (1-methylcyclohexyloxycarbonyloxy) styrene / 4-hydroxystyrene / methyl methacrylate polymer, 4-
(T-amyloxycarbonylmethoxy) styrene / 4
-Hydroxystyrene / methyl methacrylate polymer, 4- (t-amyloxycarbonylmethoxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer, 4- (t-amyloxycarbonyloxy) styrene / 4-hydroxystyrene / Methyl methacrylate polymer, 4- (t-amyloxycarbonyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer, 4- (pentyloxycarbonyloxy) styrene / 4-hydroxystyrene / propyl methacrylate polymer , 4- (2-methylpentyloxycarbonyloxy) styrene / 4-hydroxystyrene / t-butyl methacrylate polymer and the like.

The acid generator (hereinafter referred to as PAG) used in the present invention is not particularly limited as long as it is a substance capable of generating a Bronsted acid or a Lewis acid when exposed to activating radiation, and may be an onium salt or a halogenated salt. Organic compounds,
Known compounds such as quinonediazide compounds, α, αbis (sulfonyl) diazomethane compounds, α-carbonyl-α-sulfonyldiazomethane compounds, sulfone compounds, organic acid ester compounds, organic acid amide compounds, and organic acid imide compounds can be used. it can. Examples of onium salts include diazonium salts, ammonium salts, iodonium salts such as diphenyliodonium triflate, sulfonium salts such as triphenylsulfonium triflate,
Examples thereof include phosphonium salts, arsonium salts, oxonium salts and the like.

The halogenated organic compounds include halogen-containing oxadiazole compounds, halogen-containing triazine compounds, halogen-containing acetophenone compounds, halogen-containing benzophenone compounds, halogen-containing sulfoxide compounds, halogen-containing sulfone compounds,
Halogen-containing thiazole compounds, halogen-containing oxazole compounds, halogen-containing triazole compounds, halogen-containing 2-pyrone compounds, other halogen-containing heterocyclic compounds, halogen-containing aliphatic hydrocarbon compounds,
Examples thereof include halogen-containing aromatic hydrocarbon compounds and sulfenyl halide compounds. Specifically, tris (2,
3-dibromopropyl) phosphate, tris (2,3
-Dibromo-3-chloropropyl) phosphate, tetrabromochlorobutane, hexachlorobenzene, hexabromobenzene, hexabromocyclododecane, hexabromobiphenyl, allyltribromophenyl ether, tetrachlorobisphenol A, tetrabromobisphenol A, tetrachlorobisphenol A bis (chloroethyl) ether, tetrabromobisphenol A bis (bromoethyl) ether, bisphenol A bis (2,3-dichloropropyl) ether, bisphenol A bis (2,3-dibromopropyl) ether, tetrachlorobisphenol A's screw (2,3-
Dichloropropyl) ether, bis (2,3-dibromopropyl) ether of tetrabromobisphenol A,
Tetrachlorobisphenol S, tetrabromobisphenol S, tetrachlorobisphenol S bis (chloroethyl) ether, tetrabromobisphenol S bis (bromoethyl) ether, bisphenol S bis (2,3-dichloropropyl) ether, bisphenol S bis (2,3-dibromopropyl) ether,
Tris (2,3-dibromopropyl) isocyanurate, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4- (2-hydroxyethoxy) -3,5- Halogen-based flame retardants such as dibromophenyl) propane, dichlorodiphenyltrichloroethane, pentachlorophenol, 2,4,6-trichlorophenyl 4-nitrophenyl ether, 2,4
-Dichlorophenyl 3'-methoxy-4'-nitrophenyl ether, 2,4-dichlorophenoxyacetic acid,
4,5,6,7-tetrachlorophthalide, 1,1-bis (4-chlorophenyl) ethanol, 1,1-bis (4
-Chlorophenyl) -2,2,2-trichloroethanol, 2,4,4 ', 5-tetrachlorodiphenyl sulfide, 2,4,4', 5-tetrachlorodiphenyl sulfone and other organic chloro-based pesticides are exemplified. It

Specific examples of the quinonediazide compound include:
1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,1-naphthoquinonediazide-4-sulfonic acid ester Ester, 2,1-benzoquinonediazide-5
Sulfonic acid ester of quinonediazide derivative such as sulfonic acid ester, 1,2-benzoquinone-2-diazide-4-sulfonic acid chloride, 1,2-naphthoquinone-2-diazide-4-sulfonic acid chloride, 1,2-
Sulfonic acid of quinonediazide derivative such as naphthoquinone-2-diazide-5-sulfonic acid chloride, 1,2-naphthoquinone-1-diazide-6-sulfonic acid chloride and 1,2-benzoquinone-1-diazide-5-sulfonic acid chloride Examples include chloride.

Examples of the α, α bis (sulfonyl) diazomethane compounds include α, α having an unsubstituted, symmetrically or asymmetrically substituted alkyl group, alkenyl group, aralkyl group, aromatic group or heterocyclic group. Examples include α-bis (sulfonyl) diazomethane. Specific examples of the α-carbonyl-α-sulfonyldiazomethane compound include an α- having an unsubstituted, symmetrically or asymmetrically substituted alkyl group, alkenyl group, aralkyl group, aromatic group, or heterocyclic group. Carbonyl-α-sulfonyldiazomethane and the like can be mentioned. Specific examples of the sulfone compound include a sulfone compound having an unsubstituted, symmetrically or asymmetrically substituted alkyl group, alkenyl group, aralkyl group, aromatic group, or heterocyclic group,
Examples thereof include disulfone compounds.

Examples of the organic acid ester include carboxylic acid ester, sulfonic acid ester, and phosphoric acid ester, and examples of the organic acid amide include carboxylic acid amide, sulfonic acid amide, and phosphoric acid amide. As, carboxylic acid imide, sulfonic acid imide,
Examples thereof include phosphorimide.

These PAGs may be used alone or in combination of two or more. The blending amount of these PAGs is usually 0.01 part by weight, preferably 0.2 part by weight, with respect to 100 parts by weight of the resin used in the present invention.
The upper limit is usually 50 parts by weight, preferably 30 parts by weight.
If it is less than 0.01 parts by weight, it becomes impossible to form a pattern. If the amount exceeds 50 parts by weight, problems such as easy occurrence of undeveloped residue and deterioration of pattern shape occur, and in any case, it is not preferable in terms of resist performance.

In the present invention, the resist composition comprising the resin and PAG is used by dissolving it in a solvent. As the solvent, those generally used as a solvent for a resist composition can be used, and specific examples thereof include ketones such as acetone, methyl ethyl ketone, cyclohexanone, cyclopentanone, cyclopentanone, cyclohexanone; n-propanol. , I-propanol, n-
Alcohols such as butanol, i-butanol, t-butanol, cyclohexanol; ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dioxane; ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol mono Alcohol ethers such as ethyl ether; Esters such as propyl formate, butyl formate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate; 2-
Oxycarboxylic acid esters such as methyl oxypropionate, ethyl 2-oxypropionate, methyl 2-methoxypropionate and ethyl 2-methoxypropionate; cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate. Propylene glycols such as propylene glycol, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether, etc .; diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc. The di Tylene glycols; halogenated hydrocarbons such as trichloroethylene; aromatic hydrocarbons such as toluene and xylene; polarities such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylacetamide, N-methylpyrrolidone Examples thereof include solvents, and these may be used alone or in combination of two or more.

In the present invention, additives which are generally added to the resist composition as additives, such as surfactants, storage stabilizers, sensitizers, anti-striation agents, low molecular weight phenol compounds, etc., are compatible additives. Agents can be included.

In the composition of the present invention, the polymer having the constitutional unit represented by the above formula (1) undergoes the action of an acid generated from an acid generator upon irradiation with radiation, and has a solubility in an irradiated portion. Change. The composition of the present invention acts as a positive resist by using an alkaline developer. It is considered that the presence of the structural unit represented by the formula (1) or (2) in the polymer improves the resist properties such as dry etching resistance and resolution.

In the resist composition of the present invention, an alkaline aqueous solution is usually used as an alkaline developing solution. Specific examples thereof include aqueous solutions of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium silicate, and ammonia; ethylamine, propyl. Aqueous solutions of primary amines such as amines;
Aqueous solutions of secondary amines such as diethylamine and dipropylamine; aqueous solutions of tertiary amines such as trimethylamine and triethylamine; aqueous solutions of alcohol amines such as diethylethanolamine and triethanolamine; tetramethylammonium hydroxide, tetraethylammonium hydroxide, Examples thereof include aqueous solutions of quaternary ammonium hydroxide such as trimethylhydroxymethylammonium hydroxide, triethylhydroxymethylammonium hydroxide and trimethylhydroxyethylammonium hydroxide. Further, if necessary, a water-soluble organic solvent such as methanol, ethanol, propanol, or ethylene glycol, a surfactant, a resin dissolution inhibitor, or the like can be added to the alkaline aqueous solution.

A resist film can be formed by applying a resist solution prepared by dissolving the resist composition of the present invention in a solvent onto the surface of a substrate such as a silicon wafer by a conventional method and then removing the solvent by drying. As a coating method at this time, spin coating is particularly preferred. The exposure source used in the exposure for forming the pattern on the resist film thus obtained is deep ultraviolet ray, KrF
Examples of electron beam sources include excimer laser light, X-rays, and electron beams. Furthermore, it is preferable to perform heat treatment (post-exposure bake) after the exposure because the sensitivity can be improved and stabilized.

[0022]

EXAMPLES The present invention will be described in more detail below with reference to Reference Examples, Synthesis Examples and Examples. In addition, part and% in each example
Is weight basis unless otherwise specified.

(Synthesis Example 1) 4- (t-butoxycarbonylmethyloxy) styrene / 4-hydroxystyrene /
t-butyl methacrylate polymer polymerization step 4-vinylphenol 72.1 g (0.60 mol),
17.1 g of t-butyl methacrylate (0.12 mo
l), 1.5 g of azobisisobutyronitrile (0.0
(09 mol) and 150 ml of dioxane were charged into a 1-liter flask, and the mixture was stirred at 80 ° C. for 20 hours under a nitrogen stream. The obtained reaction liquid was put into 20 liter of xylene, and the generated precipitate was filtered. The obtained solid content was dissolved in 200 ml of diethyl ether and 10 liter of n-
The mixture was poured into hexane and the resulting precipitate was filtered (reprecipitation operation). This reprecipitation operation was repeated 3 times and then dried,
6.3 g of 4-hydroxystyrene / t-butyl methacrylate polymer was obtained. As a result of GPC analysis, the obtained polymer was Mw = 5,130. Also, ¹ H-NM
As a result of R spectrum analysis, 4-hydroxystyrene / t
The polymerization ratio of -butyl methacrylate was 71/29.

Modification step 23.6 g of the 4-hydroxystyrene / t-butyl methacrylate polymer obtained above and 150 ml of acetone were charged into a 500 ml flask and dissolved. This is t-
Butyl bromoacetate 7.2g (0.037mo
1), anhydrous potassium carbonate 6.9 g (0.05 ml) and potassium iodide 8.3 g (0.05 mol) were added, and 50
The mixture was stirred at 0 ° C for 8 hours. After removing salts from the obtained reaction solution, the reaction solution was poured into 5 liters of n-hexane and the resulting precipitate was filtered. The obtained solid content was dissolved in 100 ml of diethyl ether, poured into 5 liters of hexane, and the generated precipitate was filtered (reprecipitation operation). After repeating this reprecipitation operation twice, it was dried and 29.3 g of 4- (t-
Butoxycarbonylmethyloxy) styrene / 4-hydroxystyrene / t-butyl methacrylate polymer was obtained. The obtained polymer was analyzed by GPC and Mw =
It was 5,310. As a result of ¹ H-NMR spectrum analysis, the polymerization ratio of 4- (t-butoxycarbonylmethyloxy) styrene / 4-hydroxystyrene / t-butylmethacrylate was 21/51/28.

(Synthesis Example 2) 4- (t-amyloxycarbonylmethyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer polymerization step 19.1-methylcyclohexyl methacrylate 29.1 g instead of t-butyl methacrylate (0.16mo
2) g of 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer was obtained in the same manner as in the polymerization step of Synthesis Example 1 except that the above was adopted. As a result of GPC analysis, the obtained polymer was Mw = 6,330. As a result of ¹ H-NMR spectrum analysis, the polymerization ratio of 4-hydroxystyrene / 1-methylcyclohexyl methacrylate was 64/36. Modification step The same as the modification step of Synthesis Example 1 except that the polymer obtained in the polymerization step was 10.0 g, and t-amyl bromoacetate was 2.63 g (0.0126 mol) instead of t-butyl bromoacetate. Then, 1.05 g of 4- (t-amyloxycarbonylmethyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer was obtained. As a result of GPC analysis, the obtained polymer was Mw = 6,910. As a result of ¹ H-NMR spectrum analysis, the polymerization ratio of 4- (t-amyloxycarbonylmethyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate was 17/45/38.

(Synthesis Example 3) 4- (t-butoxycarbonyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer a 4-hydroxystyrene / 1-methyl obtained in the polymerization step of Synthesis Example 2 Cyclohexyl methacrylate polymer 1
0.0 g and 100 ml of acetone were charged and dissolved in a 500 ml flask, 2.75 g (0.0126 mol) of di-t-butyl dicarbonate and 6.9 g (0.05 mol) of anhydrous potassium carbonate were added thereto, and the mixture was stirred at 8 ° C. at 8 ° C. Stir for hours. Thereafter, by the same operation as in Synthesis Example 1, 10.9
g of 4- (t-butoxycarbonyloxy) styrene /
4-Hydroxystyrene / t-butyl methacrylate polymer a was obtained. As a result of GPC analysis, the obtained polymer was Mw = 6,790. As a result of ¹ H-NMR spectrum analysis, the polymerization ratio of 4- (t-butoxycarbonyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate was 12/5.
It was 1/37.

(Synthesis Example 4) 4- (t-butoxycarbonyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer b 4-hydroxystyrene / 1-methyl obtained in the polymerization step of Synthesis Example 2 Cyclohexyl methacrylate polymer 1
Into a 500 ml eggplant-shaped flask, 0.0 g and 100 ml of acetone were charged and dissolved, to which 11.0 g (0.05 mol) of di-t-butyl dicarbonate and 8.3 g (0.06 mol) of anhydrous potassium carbonate were added, and 50 8 at ℃
Stir for hours. Thereafter, the same operation as in Synthesis Example 1
1.8 g of 4- (t-butoxycarbonyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate polymer b was obtained. As a result of GPC analysis, the obtained polymer was Mw = 8,190. As a result of ¹ H-NMR spectrum analysis, the polymerization ratio of 4- (t-butoxycarbonyloxy) styrene / 4-hydroxystyrene / 1-methylcyclohexyl methacrylate was 48/16/36.

(Examples 1 to 4) 100 parts of the polymers obtained in the above Synthesis Examples 1 to 4, 5 parts of triphenylsulfonium triflate as an acid generator, 0.01 part of a fluorine-containing surfactant and 440 parts of ethyl lactate. And was filtered through a 0.1 μm polytetrafluoroethylene filter (manufactured by Millipore) to prepare a resist solution. After spin-coating this resist solution on a silicon wafer,
A resist film having a thickness of 1.0 μm was formed by baking for 0 seconds. This wafer was exposed using a KrF excimer stepper (NA = 0.45) and a test reticle. Then, after baking at 90 ° C. for 60 seconds, an immersion phenomenon with an aqueous solution of tetramethylammonium hydroxide was carried out for 1 minute to obtain a positive pattern. Table 1 shows the sensitivities of these resist films and the resolution when a good pattern obtained by optimizing the exposure is shown. Further, the patterned wafer was etched with a dry etching device (DEM451T manufactured by Nichiden Anelva) at a power of 300 W, a pressure of 0.03 Torr, a gas CF ₄ / H ₂ , and a frequency of 13.56 MHg. It was found that even the wafer using the polymer of 3 was etched only where there was no pattern, and most of Synthesis example 4 was also etched. Further, when the resist pattern after etching was observed, the shape before etching was almost maintained.

[0029]

[Table 1]

[0030]

As described above, according to the present invention, a resist material having excellent resist properties such as sensitivity, resolution and etching resistance and suitable for lithography using deep ultraviolet rays having a short wavelength or KrF excimer laser light can be obtained. The resist composition of the present invention is particularly suitable as a positive resist for fine processing of semiconductor devices.

Claims (1)

[Claims] 1. General formulas (1), (2) and (3): Embedded image Embedded image (In the formulas (1) to (3), R ^{1 to} R ³ are each independently a hydrogen atom, a substituted alkyl group having 1 to 4 carbon atoms, a halogen atom, a cyano group or a nitro group, and R ⁴ is the following formula. (4) or (5) Embedded image (In the formulas (4) and (5), R ^{6 to} R ¹³ are each independently a hydrogen atom, a linear, branched, or cyclic C 1-8 substituted alkyl group, a substituted alkenyl group, or a substituted aryl. R ⁶ and R ⁷ , R ¹¹ and R ¹² may be bonded to each other to form a ring), and R ⁵ is a linear, branched or cyclic C 1 to C 8 group. Is a substituted alkyl group, a substituted alkenyl group, or a substituted aryl group. The ratio of the units represented by the formulas (1), (2) and (3) is k,
is represented by m and n, k + m + n = 1, 0 <k <0.95,
0 <m <0.95, 0.05 ≦ n ≦ 0.6, 0.1 ≦ k
/ (K + m) <1. ) A resist composition comprising a polymer having a structural unit represented by the formula (1) and a radiation functional component which generates an acid when exposed to activating radiation.