GB2356258A

GB2356258A - Chemical amplification type resist composition

Info

Publication number: GB2356258A
Application number: GB0027168A
Authority: GB
Inventors: Yasunori Uetani; Kazuhiko Hashimoto; Yoshiko Miya; Hiroki Inoue
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 1999-11-09
Filing date: 2000-11-07
Publication date: 2001-05-16
Anticipated expiration: 2020-11-07
Also published as: JP4711018B2; JP2010204672A; DE10054996A1; GB2356258B; GB0027168D0; TW527522B; KR20010051470A

Abstract

A chemical amplification type resist composition comprises<BR> a radiation sensitive compound; and<BR> a binder resin which is soluble in alkali by itself or becomes soluble in alkali by a chemical change caused by the action of the radiation sensitive compound after irradiation, and has a polymerization unit derived from a monomer of formula (I): <EMI ID=1.1 HE=23 WI=67 LX=647 LY=992 TI=CF> <PC>wherein Q represents hydrogen, methyl or a fluoroalkyl having 1 to 4 carbon atoms; R<SP>1</SP> represents an alkyl having 1 to 14 carbon atoms;<BR> provided that at least one of Q and R<SP>1</SP> has at least one fluorine atom. The composition exhibits a high transmittance in light exposure using a light source having a wavelength of 170 nm or less and a high resolution in KrF or ArF light exposure, and has a sufficient contrast.

Description

2356258 CHEMICAL AMPLIFICATION TYPE RESIST COMPOSITION

BACKGROUND OF THE INVENTION

The present invention relates to a chemical amplification type resist composition usable in the fine processing of semiconductors.

The fine processing of semiconductors has usually been performed by adopting the lithography process using a resist composition. In the lithography process, as indicated by the Rayleigh's equation for limit of diffraction, it principally becomes more possible to improve resolution with shortening wavelength for exposure. Wavelength of light source for lithography process in the production of semiconductors has been becoming shorter and shorter year by year, in such order as g-ray at a wavelength of 436 nm, i-ray at a wavelength of 365 nm, KrF excimer laser at a wavelength of 248 nm and ArF eximer laser at a wavelength of 193 nm. Furthermore, F2 excimer laser at a wavelength of 157 is attracting attention as.a next generation of the light source. For exposure with KrF excimer laser or that with ArF excimer laser, so-called chemical amplification type resists utilizing a catalytic action of an acid generated by light exposure have frequently been used because of their excellent sensitivity. It is also considered that chemical amplification type resists will be used for exposure with F2 excimer laser because of their excellent sensitivity.

Conventionally, polyvinylphenol resins have been used as resists for exposure with KrF excimer laser. As resists for exposure with ArF excimer laser, resins without an aromatic ring and, instead, having an alicyclic ring are used in order to insure the transmittance of the resists and to confer a dry etching resistance. Various resins have, been known as resins 5 having an alicyclic ring, including one described by D. C. Hof er, Journal of Photopolymer Science and Technology, Vol. 9, No. 3, pages 387 - 398 (1996). In addition, it has been described, in S. Takechi et al., Journal of Photopolymer Science and Technology, Vol. 9, No. 3, pages 475 - 487 (1996) and JP-A- 9-73173, that a positive working action is realized, and a high dry etching resistance, high resolution and a good adherence to substrate are obtained by using polymers or copolymers of 2-methyl-2-adamantyl methacrylate as resins for chemical amplification type resist.

The known resins used in resists for exposure with KrF excimer laser or that with ArF excimer laser, however, did not exhibit a sufficient transmittance to a light having a wavelength of 170 nm or shorter, for example, F2 excimer laser at 157 nm. Insufficient transmittance adversely affects various performances including profile, contrast, sensitivity and so on.

The object of the present invention is to provide a chemical amplification type resist composition which is excellent in transmittance to a light having a wavelength of 170 nm or shorter and is suitably used particularly in laser lithography process with F2 excimer. The present inventors have found the fact that the transmittance to the wavelength 157 nm of F2 excimer laser can be improved by using a resin having a polymerization unit derived from a specific monomer, as the resin constituting a resist composition. The present invention has thus been completed.

SUMMARY OF THE INVENTION

The present invention provides a chemical amplification type resist composition comprising a radiation sensitive compound; and a binder resin which is soluble in alkali by itself or becomes soluble in alkali by a chemical change caused by an action of the radiation sensitive compound after irradiation with a radiation, and has a polymerization unit derived from a monomer represented by the following formula (I):

Q I -R1 CH2-u-u-u 11 U wherein Q represents hydrogen, methyl or a fluoroalkyl having 1 to 4 carbon atoms; R' represe nts an alkyl having 1 to 14 carbon atoms which may be optionally substituted with halogen, hydroxyl or alicyclic ring, or an alicyclic or a lactone ring which may be optionally substituted with halogen, hydroxyl or alkyl; provided that at least one of Q and R' has at least one fluorine atom.

PREFERRED EMBODIMENT OF THE INVENTION The chemical amplification type resist composition according to the invention contains a binder resin and a radiation sensitive compound.

- 3 The binder resin contained in the chemical amplification type resist composition has a polymerization unit derived from an acrylic acid ester represented by the formula (I).

In the formula (I), at least one of Q and R1 has at least 5 one fluorine atom, In the formula, Q represents hydrogen, methyl or a fluoroalkyl having 1 to 4 carbon atoms. The fluoroalkyl may be straight - chained or branched in the case where it has 3 or more carbon atoms. The f luoroalkyl preferably has two or more fluorine atoms. Acrylic acid esters wherein Q is a trifluoromethyl group are easily available.

Ri represents an alkyl having 1 to 14 carbon atoms which may be optionally substituted with halogen, hydroxyl or alicyclic ring, or an alicyclic or a lactone ring which may be optionally substituted with halogen, hydroxyl or alkyl.

The alkyl having 1 to 14 carbon atoms which may be optionally substituted with halogen, hydroxyl or alicyclic ring may be straight-chained or branched in the case where it has 3 or more carbon atoms. Examples of the halogen as the substituent include fluorine, chlorine and bromine. Examples of the alicyclic ring as the substituent include cyclopentyl ring, cyclohexyl ring, bicyclo[2.2.11heptyl ring, bicyclo[4.3.0]nonyl ring, bicyclo[4.4.0]decanyl ring, tricyclo[5.2. 1. 02,6 1 decanyl ring, adamantyl ring and the like.

As the alkyl having 1 to 14 carbon atoms which may be optionally substituted with halogen, hydroxyl or alicyclic ring, preferred groups are fluoroalkyls having 1 to 14 carbon atoms which are substituted with at least one fluorine and which may be optionally substituted with a hydroxyl group.

The alkyl group as a substituent on the alicyclic ring or the lactone ring is a lower alkyl group usually having about 1 to 4 carbon atoms. The alkyl group may be straight -chained or branched when it has 3 or more carbon atoms. Examples of the halogen as the substituent on the alicyclic ring or the lactone ring include fluorine, chlorine and bromine.

Examples of the alicyclic ring as R1 include cyclopentyl ring, cyclohexyl ring, bicyclo[2.2.11heptyl ring, bicyclo[4.3.0]nonyl ring, bicyclo[4.4.0]decanyl ring, tricyclo[5.2.1.02,61decanyl ring, adamantyl ring and the like. The lactone ring as R1 include 2-oxooxetane-3-yl ring, 2oxooxolane-3-yl ring, 2-oxooxane-3-yl ring and 2-oxepanone3-yl ring.

When R1 has at least one fluorine atom, R1 is preferably a group represented by the following formula (II):

OH R 2 1 1 3 CH2-CH CH-R (R) wherein R 2 represents hydrogen, an alkyl or a fluoroalkyl, R 3 represents a fluoroalkyl, the total number of carbon atoms in 20 R 2 and R 3 is 1 to 11, and n represents 0 or 1, in the viewpoint of availability of the resin. The alkyl group as R 2 and the fluoroalkyl group as R 2 or R 3 may be straight -chained or branched when they have 3 or more carbon atoms. The f luoroalkyl group pref erably has two or more fluorine atoms. A perfluoroalkyl group may also be possible.

When R1 has a hydroxyl group, the conformability of a - 5 - resin to a developer is improved as the result of increased hydrophilic property of the resin.

Examples of fluoroalkyl acrylate represented by the formula (I) include the following compounds:

2,2,2-trifluoroethyl acrylate, 2,2,2-trifluoroethyl methacrylate, 1-trifluoromethyl-2,2,2-trifluoroethyl acrylate, 1-trifluoromethyl-2,2,2-trifluoroethy1 methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 1H,lH,11H-eicosafluoroundecyl acrylate, 1H,lH,11H-eicosafluoroundecyl methacrylate, 3-(perfluoro-3-methylethyl)-2-hydroxypropyl methacrylate, 3-(perfluoro-3-methylbutyl)-2-hydroxypropy1 methacrylate, 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate, 3-(perfluoro-7-methyloctyl)-2-hydroxypropyl methacrylate, 3-(perfluoroethyl)-2-hydroxypropyl methacrylate, 3-(perfluorobutyl)-2-hydroxypropyl methacrylate, 3-(perfluorohexyl)-2-hydroxypropyl methacrylate, 3-(perfluorooctyl)-2-hydroxypropyl methacrylate, 3-(perfluoro-3-methylbutyl)-2-hydroxypropyl acrylate, 3-(perfluoro-2-methylethyl)-2-hydroxypropyl acrylate, 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl acrylate, 3-(perfluoro-7-methyloctyl)-2-hydroxypropyl acrylate, 3-(perfluoroethyl)-2-hydroxypropyl acrylate, 3-(perfluorobutyl)-2-hydroxypropyl acrylate, 3-(perfluorohexyl)-2-hydroxypropyl acrylate, 3-(perfluorooctyl)-2-hydroxypropyl acrylate, CF3 CH3 CF3 9H3 CH2=6-c-o CH2=6-C-0-C-CH, 11 0 0 6H, 11 qF3 C 3 F3 CH2=C-C-0-C CH2=c-c 0-10 0 -q CH3 0 0 F3 CH CF3 CH2=C-C-0 2=6-c-O 0 0 0 YF3 9H3 Y F3 CH2=C-C-0-CH2CH2CH20F CH2=C-C-0-C-CH2CI 11 0 6H3 0 Y F3 F3 -,CH3 CH2=c-c-o CH2=C-C-0 0 0 0 0 0 OH F3 F3 -j7\ CH2=C-C-O-q CH2=C-C-0 11 I 1 0 0 OH CF3 Br F3 I _q CH2=C-C-0 CH2=C-C-0 11 0-4 OH 0 and the like.

A polymer unit represented by the following formula (Ia) is formed by the polymerization of a monomer represented by the formula (I):

Q I -CH2-U a) I U=U I U 1 1 R wherein Q and R1 are as defined above.

The binder resin comprised in the chemical amplification type resist composition of the present invention is soluble in alkali by itself or becomes soluble in alkali by a chemical change caused by an action of a radiation sensitive compound 5 described below after irradiation with a radiation.

When a part of a resist film irradiated with a radiation is removed by the alkali development, such a resist is called positive type. In the positive working resist of chemical amplification type, an acid or abase generated from a radiation sensitive compound at a part irradiated with a radiation makes said part soluble in alkali by diffusing upon a heat treatment afterwards (post exposure bake) and cleaving a protective group in the resin or the like. The positive working resist of chemical amplification type includes:

1) those comprising a radiation sensitive compound, a binder resin soluble in alkali, and a dissolution inhibitor which has a protective group cleavable by the action of an acid or a base, and has by itself a dissolution- inhibiting ability against a binder resin soluble in alkali but loses its dissolution- inhibiting ability after said protective group is cleaved by the action of an acid or a base; 2) those comprising a radiation sensitive compound and a binder resin which has a protective group cleavable by the action of an acid or a base and is by itself insoluble or difficultly soluble in alkali but becomes soluble in alkali after said protective group is cleaved by the action of an acid or a base; and others.

8 When a binder resin is soluble in alkali and a part irradiated with a radiation is hardened and becomes insoluble in alkali, and only a part without irradiation with a radiation is removed by the alkali development, such a resist is called negative type. In the negative working resist of chemical amplification type, the binder resin is normally soluble in alkali. Such a negative working resist of chemical amplification type usually comprises, in addition to the binder resin and the radiation sensitive component, a cross-linking agent. An acid or a base generated from a radiation sensitive compound at the part irradiated with a radiation makes said part hardened and insoluble in alkali by diffusing upon a heat treatment afterwards (post exposure bake) and acting on the cross-linking agent..

Examples of the polymerization unit that confers solubility in alkali on the binder resin used in the invention (hereinaf ter I such a unit is ref erred to as alkall-soluble unit) include units having a phenol basic structure, units having a (meth)acrylic ester basic structure in which an alicyclic ring and a carboxyl group are present in the alcoholic moiety of the ester, units from unsaturated carboxylic acid and the like. Specific examples thereof include vinylphenol unit, isopropenylphenol unit, (meth)acrylic acid alicyclic ester in which a carboxyl group is present on its alicyclic ring, (meth)acrylic acid unit and the like. By introducing relatively large number of such alkali- soluble unit in the resin, the resin itself becomes soluble in alkali. The binder resin being soluble in alkali by itself as defined in the present invention may have polymerization unit that does not confer solubility in alkali on the binder resin (hereinafter, such a unit is referred to as alkali-insoluble unit) in addition to the above alkali-soluble unit, as far as the resin as a whole is soluble in alkali. Examples of the resin having the alkali -insoluble unit include a resin having a vinylphenol unit or a isopropenylphenol unit in which the hydroxyl group is partly alkyl-esterified, a resin obtainable by copolymerization of vinylphenol or isopropenylphenol and another polymerizable unsaturated compound, a resin obtainable by copolymerization of (meth) acrylic acid alicyclic ester and (meth)acrylic acid, and the like.

Examples of resins, which are by itself insoluble or difficulty soluble in alkali but become soluble in alkali by the action of the radiation sensitive compound after irradiation of a radiation, include those having polymerization unit with a protective group which has the dissolutioninhibiting ability into the alkali developer but is.cleavable by the action of an acid or a base, in addition to alkali soluble unit. The protective group which has the dissolutioninhibiting ability into the alkali developer but is cleavable by the action of an acid or a base is not particularly limited.

Examples of the protective group, which has the dissolution -inhibiting ability into the alkaline developer but is cleavable by the action of an acid, include tert-butyl, groups containing an oxygen atom connecting to a tertially carboi- atom such as tert-butoxycarbonyl and tertbutoxycarbonylmethyl, acetal type groups such as tetrahydro-2-pyranyl, tetrahydro-2-furyl, 1-ethoxyethyl, 1(2- methylpropoxy)ethyl, 1-(2-methoxyethoxy)ethyl, 1-(2acetoxyethoxy)ethyl, 1[2-(l-adamantyloxy)ethoxylethyl and 1-[2-(ladamantanecarbonyloxy)ethoxylethyl; residues of 5 non-aromatic ring compound such as 3-oxocyclohexyl, 4methyltetrahydro-2-pyrone-4-yl (derived from mevalonic lactone) and 2-alkyl-2-adamantyl and the like. These protective groups replace the hydrogen atom in the phenolic hydroxyl group or the carboxyl group. These protective groups can be introduced into a resin by subjecting an alkali-soluble resin having a phenolic hydroxyl group or a carboxyl group to the known protecting group-introducing reaction or by copolymerizing an unsaturated compound having such a group with another monomer.

Examples of the protective group which has the dissolution -inhibiting ability into the alkaline developer but is cleavable by the action of a base include alkylcarbamate or cycloalkylcarbamate groups. Examples of resins with a polymerization unit having a protective group which has the dissolution -inhibiting ability into the alkaline developer but is cleavable by the action of a base include those with a unit which has a phenol basic structure and in which phenolic hydroxyl groups are partly substituted by alkylcarbamoyloxy groups or cycloalkylcarbamoyloxy groups.

A polymerization unit derived from a monomer represented by the formula (I) may be an alkali-soluble unit.

Alternatively, the monomer represented by the formula (I) may has a protective group which has the dissolution-inhibiting ability into the alkaline developer but is cleavable by the action of an acid or a base. Excepting the above described cases, the binder resin of the present invention has an alkali-soluble unit or a polymerization unit having a group which becomes soluble in alkali by a chemical change caused by the action of a radiation sensitive compound after irradiation of a radiation, in addition to the polymerization unit derived from a monomer represented by the f ormula (I). In this case, the binder resin is produced by copolymerizing a monomer represented by the formula (I) and a monomer leading an alkali-soluble unit or a monomer that confers solubility in alkali of the resin by a chemical change caused by the action of a radiation sensitive compound after irradiation of a radiation. The copolymerization can be conducted according to a conventional process. For example, respective monomers are dissolved in a suitable solvent, then the polymerization is commenced in the presence of a polymerization initiator and the reaction proceeded towards termination.

The polymerization unit derived from the monomer represented by the formula (I) gives the binder resin containing the unit an excellent transmittance to a light having a wavelength of 170 nm or less, for example, F2 excimer laser at a wavelength of 157 nm. Therefore, it is suitable to present the polymerization unit derived from the monomer of the formula (1) in a range which allows the resin to have an excellent transmittance to a light having a wavelength of 170 nm or less as well as to be soluble in alkali or to become soluble in alkali by the action of a radiation sensitive compound after irradiation of a radiation. Depending on the kind and type, usually the ratio of the polymerization unit derived from the monomer of the formula (I) is 10 to 100% by mole based on the total units in the resin.

When the binder resin contains a relatively high ratio of the alkali-soluble unit, the resin itself becomes soluble in alkali. The binder resin soluble by itself in alkali can be formulated with a dissolution inhibitor and a radiation sensitive compound to form a positive working resist, or can be formulated with a cross-linking agent and a radiation sensitive compound to form a negative working resist.

Examples of the dissolution inhibitor used in the positive working resist in which the binder resin itself is soluble in alkali include phenol compounds in which the phenolic hydroxyl groups are protected by groups having dissolution inhibiting ability to alkaline developer but cleavable by the action of an acid or a base. Examples of the group having dissolution inhibiting ability to alkaline developer but cleavable by the action of an acid include tert- butoxycarbonyl group, which replaces hydrogen in the phenolic hydroxyl group. Examples of the dissolution inhibitor having the group having dissolution inhibiting ability to alkaline developer but cleavable by the action of an acid include 2,2-bis(4tertbutoxycarbonyloxyphenyl)propane, bis(4-tertbutoxycarbonyloxyphenyl)sulfone, 3,5-bis(4-tertbutoxycarbonyloxyphenyl)-1, 1,3-trimethyl indane and the like. Examples of the group having dissolution inhibiting ability to alkaline developer but cleavable by the action of a base include alkylcarbamate group or cycloalky1carbamate group and the like. Examples of dissolution inhibitor having a group cleavable by the action of a base include phenol compounds in which the phenolic hydroxyl group is replaced by an alkylcarbamoyloxy group or a cycloalkylcarbamoyloxy group. The binder component def ined in this invention includes these dissolution inhibitors as well as the binder resin.

The cross-linking agent used in a negative working resist in which the binder resin itself is soluble in alkali may be anyone that causes cross-linking of the binder resin by the action of an acid or a base. Usually compounds having a methylol group or their alkyl ethers as the cross-linking agents. Specific examples thereof include methylol melamines as well as alkyl ethers thereof such as hexamethylol melamine, pentamethylol melamine, tetramethylol melamine, hexamethoxymethyl melamine, pentamethoxymethyl melamine and tetramethoxymethyl melamine; methylol benzoguanamines as well as alkyl ethers thereof such as tetramethylol benzoguanamine, tetramethoxymethyl benzoguanamine and trimethoxymethyl benzoguanamine; 2, 6-bis(hydroxymethyl)-4-methylpheno1 as well as alkyl ethers thereof; 4- tert-butyl-2,6bis(hydroxymethyl)phenol as well as alkyl ethers thereof; 5ethyl-1,3-bis(hydroxymethyl)perhydro-1,3,5-triazine-2-one (common name: N-ethyldimethylol triazone) as well as alkyl ethers thereof; N,N'-dimethylolurea as well as dialkyl ethers thereof; 3,5bis(hydroxymethyl)perhydro-1,3,5-oxadiazine-4one (common name: dimethylol urone) as well as alkyl ethers thereof; tetramethylol glyoxal diurein as well as tetramethyl ether thereof; and the like.

The binder resin having a unit which confers solubility in alkali on the resin by a chemical change caused by a radiation sensitive compound af ter irradiation of a radiation and a unit derived from the monomer of the formula (I) can be formulated with a radiation sensitive compound to form a positive working resist. Sometimes, the monomer of the formula (I) itself becomes a unit which confers solubility in alkali on the resin by a chemical change caused by a radiation sensitive compound after irradiation of a radiation. Among the polymerization unit which confers solubility in alkali on the resin by a chemical change caused by a radiation sensitive compound after irradiation of a radiation, those derived from 2-alkyl-2adamantyl (meth)acrylates can confer an excellent resolution and dryetching resistance on the resin. The 2-alkyl-2adamantyl (meth)acrylates can specifically be represented by the formula (III) shown below and form polymerization units of the formula (IIIa) shown below by their polymerization.

R R 4 1 CH2 U R I _CH2_U a) I U=U I U R 41 wherein R represents hydrogen, methyl or a fluoroalkyl having 1 to 4 carbon atoms, and R 4 represents an alkyl. The alkyl represented by R 4 may have, for example, about 1 to 8 carbon atoms. Usually, it is advantageous to be straight -chained but may be branched in the case where they have 3 or more carbon atoms. Specific examples of R 4 include methyl, ethyl, propyl, isopropyl, butyl and the like. Since 2-alkyl-2-adamantyl group in the polymerization units of 2alkyl-2-adamantyl (meth) acrylates represented by the f ormula (I I Ia) is cleaved by the action of an acid, resins having these units can be used as a radiation sensitive compound in the positive working resist using an acid generating agent.

It is particularly effective for increasing the dry etching resistance that the binder resin contains an alicyclic olefin unit represented by the following formula (IV):

(IV) 16 6 wherein R and R, which are same or different from each other, represent hydrogen, an alkyl having 1 to 3 carbon atoms, a hydroxyalkyl having 1 to 3 carbon atoms, carboxyl, cyano or a group -COOR 7 wherein R 7 is an alcohol residue, or R 5 and R6 together form a carboxylic acid anhydride residue represented by - C(=O)OC(=O)-, and a polymerization unit of unsaturated dicarboxylic acid anhydride selected f rom maleic anhydride and itaconic anhydride in addition to the polymerization unit derived f rom the f ormula M.

6 In the formula (IV), R5 and R, which are same or dif f erent from each other, may represent hydrogen, an alkyl having 1 to 3 carbon atoms, a hydroxyalkyl having 1 to 3 carbon atoms, carboxyl, cyano or a group -COOR 7 wherein R 7 is an alcohol residue, or R5 and R 6 may together f orm a carboxylic acid anhydride residue represented by -C(=O)OC(=O) -. Examples of alkyls represented by R 5 and R 6 include methyl, ethyl, propyl and the like. Examples of hydroxyalkyls represented by R 5 and R 6 -include hydroxymethyl, 2-hydroxyethyl and the like. Examples of alcohol residue represented by R 7 include alkyl having about 1 to 8 carbon atoms which may be optionally substituted, 2oxooxolane-3- or -4-yl and the like. Examples of possible substituent on alkyl include hydroxyl, alicyclic hydrocarbon residue and the like. Examples of carboxylic acid ester residue represented by -COOR7 include methoxycarbonyl, ethoxycarbonyl, 2hydroxyethoxycarbonyl, tert-butoxycarbonyl, 2-oxooxolane-3-yloxycarbonyl, 2-oxooxolane-4-yloxycarbonyl, 1,1,2-trimethylpropoxycarbonyl, 1cyclohexyl-l- methylethoxycarbonyl, 1-(4-methylcyclohexyl)-lmethylethoxycarbonyl, 1-(ladamantyl)-lmethylethoxycarbonyl and the like.

Examples of the monomer leading to the polymerization unit of alicyclic olef in represented by the f ormula (IV) include the following compounds: 2-norbornene, 2-hydroxy-5-norbornene, 5-norbornene-2- carboxylic acid, methyl 5-norbornene-2-carboxylate, tert-butyl 5-norbornene-2-carboxylate, 1-cyclohexyl-l-methylethyl 5-norbornene-2-carboxylate, 1-(4methylcyclohexyl)-l-methylethy1 5-norbornene-2carboxylate, 1-(4-hydroxycyclohexyl)-l-methylethyl 5-norbornene-2carboxylate, 1-methyll-(4-oxocyclohexyl)ethy1 5-norbornene-2carboxylate, 1-(l-adamantyl)-lmethylethyl 5-norbornene-2-carboxylate, 1-methylcyclohexyl 5-norbornene-2-carboxylate, 2-methyl-2-adamantyl 5norbornene-2-carboxylate, 2-ethyl-2-adamantyl 5-norbornene-2-carboxylate, 2-hydroxy-l-ethyl 5-norbornene-2-carboxylate, 5-norbornene-2-methanol, 5-norbornene-2,3-dicarboxylic acid anhydride and the like.

The polymerization units of unsaturated dicarboxylic acid anhydride are selected from the polymerization unit of maleic acid anhydride and the polymerization unit of itaconic acid anhydride, and can be represented, respectively, by the formulae (V) and (VI) shown below. Examples of monomer leading to these polymerization units include maleic acid anhydride, itaconic acid anhydride and the like.

CH2- C 0 ::I 040--10) 00 (V) (VI) Typical examples of binder resin, which is comprised in the resist composition of the present invention and is soluble in alkali by itself or becomes soluble in alkali by a chemical change caused by the action of a radiation sensitive compound after irradiation with a radiation, include the compounds having respective units selected from those shown by the following formulae (VII) to (XXVIII).

- 19 H 3 C yl 3 CF3 C F31 1 1-3 CH2-C CH2'C CH2- CH2-.

C=O C=O C=O Q=O C 0 0 (VE) 0 0 (Vnl) CH3T) oz) CH3 0,Z,6 C qF3 CH3 qF3 CF CF3 B 1" 3 r-3 CH2'C CH2'6 CH2'C H2- CH2- c 6 - =o C=O C=O Q=O Q=O 0 0 (IX) 0 0 0 CH3 0 CH3 oz6 (X) C C JL 0 H) l 9F3 QF CHzq 3 CH2' C CH2-CH c Q=O 0 9=) CH3 0 OH(X H) OH C CF3 CHZ CH2-CH CH2-CHCH,C -CH2'CH 4 C=O CH 6 -CH3 (X HI) 6H (X IV) 0) 3-C 0)08) OH I OH OR CH3 CF3 QF3 CH2-CH 4CH2-qH-CH2' C CH CH2'c C=O G=O 0 0 (X V) 0 0 OH) j OH) OR) 0 (XVI) S 0 I-<- j CH CH3 CH CH CH3 CH2- 3\ CHZ CH2-CH 2- CH _71C C=O q=O 6=0 H 0 9 0) 0 6 3 8 6H (X M CH (XVR) 0 R % C v / lk OH CF3 CF) CF3 CF) CH CH CH CH3 -CH2-CH -CH2-CH-/CHZ 3 2- CH 2c C=O C=O 6 6H2 CH OH/ OR) OH (X IX) CHOH CF3 CF) 6F2 (X X) 6F2 CFCF3 6F3) - f,Lj \ H3 CH2. QH3 4CH2'"' H2-c C 0=0 C=O C=0 0 1P H3 CH 6H2 00 C CHOH cF3 CF CH3-CC.CH 3 QF2 CH3 (X X V QF2 (XX I 9FC CF3 C H3 _C Hzb CH C= CH2-CH-/CH,,b 3 C=O Q: 0 6 0 PH2 CH3-b-CH3 CHOH 6H2 CH3 QF2 OH) CHOH CF2 (X X IV) tF2 CFC CF2 (X X 1) CF3 FC CF3 CH3 H27b HzCH 0 C_= 0 6=0)) 9 6 Q:O PH2 9:0 1 0 0 PH2 CH3 CHOH CH3 QHOH CF2 C F2 (F2 (F2 9FCF CFCF3 (X X V) C F3 (X X VI) CF3 CH3 HLICH O 0) P=O t=o 0 0 0 Q-0 I H3 0 0 H3 C F (C H 3 F) 'F) 0 H2 0 JHH H F2 0 F2 FCF C F3 F3 H2 H 0 H F2 F2 FCF (:O 0 PH2 0 PH2 CH3'C-CH3 CeHOH CH3.C_CH3 CHOH C F2 CF2' (F2 C CF2 FC CFCF3 C F3 (X X Via) CF 3 (X X V11) 3 wherein R 8 represents a protective group of hydroxyl. Examples of R8 include alkyl, various groups listed above as the groups cleavable by the action of an acid or a base, and the like.

In the case of a positive working resist comprising an alkali-soluble binder resin and a dissolution inhibitor having a group cleavable by the action of an acid, and in the case of a positive working resist comprising a binder resin which has a group cleavable by the action of an acid and which is insoluble or difficultly soluble in alkali but becomes soluble in alkali after the cleavable group is cleaved, an acid generating agent which generates an acid by the action of a radiation is comprised in the positive working resist.

In the case of a negative working resist comprising an alkali-soluble binder resin and a cross-linking agent, usually an acid generating agent is used as a radiation sensitive compound, because many cross-linking agents cause the cross-linking reaction by the action of an acid.

On the other hand, in the case of a positive working resist comprising analkali-soluble binder resin and a dissolution inhibitor having a group cleavable by the action of a base, and in the case of such a positive working resist comprising a binder resin which has a group cleavable by the action of a base, a base generating agent which generates a base by the action of a radiation is comprised in the positive working resist.

The acid generating agent as a radiation sensitive compound may be selected from various compounds which generate an acid by irradiating a radiation on a resist composition containing such a compound. Examples thereof include onium salts, halogenated alkyltriazine compounds, disulfone compounds, compounds having a diazomethanesulfonyl basic structure, sulfonic acid ester compounds and the like.

Specific examples of such compounds are listed below. Onium salts:

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, bis(4-tert-butylphenyl)iodonium camphor sulfonate triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium trifluoromethanesulfonate, 4-methoxyphenyldiphenylsulfonium hexafluoroantimonate, 4-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate, p-tolyldiphenylsulfonium trifluoromethanesulfonate, 2,4,6-trimethylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-tert-butylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-phenylthiophenyldiphenylsulfonium hexafluorophosphate, 4-phenylthiophenyldiphenylsulfonium hexafluoroantimonate, 1-(2-naphthoylmethyl)thioranium hexafluoroantimonate, 1-(2-naphthoylmethyl)thioranium trifluoromethanesulfonate, 4-hydroxy-l-naphthyldimethylsulfonium hexafluoroantimonate 4-hydroxy-l-naphthyldimethylsulfonium trifluoromethanesulfonate, and the like.

Halogenated alkyltriazine compounds:

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-l-naphthyl)-4,6-bis(trichloromethyl)- 1,3,5-triazine, 2-(benzo[d][1,3]dioxolane-5-yl)-4,6-bis(tirichloro methyl)-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)-1,3,5triazine, 2-(4-pentyloxystyryl)-4,6-bis(trichloromethyl)- 1,3,5-triazine, and the like.

Disulfone compounds:

diphenyl disulfone, di-p-tolyl disulfone, phenyl p-tolyl disulfone, phenyl p-methoxyphenyl disulfone, and the like.

Compounds having a diazomethane sulfonyl basic structure:

bis(phenylsulfonyl)diazomethane, bis(4-chlorophenylsulfonyl)diazomethane, bis(p-tolylsulfonyl)diazomethane, bis(4-tert-butylphenylsulfonyl)diazomethane, bis(2,4-xylylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, (benzoyl)(phenylsulfonyl)diazomethane, and the like.

Sulfonic acid ester compounds:

1-benzoyl-l-phenylmethyl p-toluenesulfonate (common name: benzoin tosilate), 2-benzoyl-2-hydroxy-2-phenylethyl p-toluenesulfonate (common name: a-methylolbenzoin tosilate), 1,2,3-benzenetriyl trismethanesulfonate, 2,6-dinitrobenzyl p-toluenesulfonate, 2-nitrobenzyl p-toluenesulfonate, 4-nitrobenzyl p-toluenesulfonate, N-(phenylsulfonyloxy)succinimide, N-(trifluoromethylsulfonyloxy)succinimide, N-(butylsulfonyloxy)succinimide, N-(10-camphorsulfonyloxy)succinimide, N-(trifluoromethylsulfonyloxy)phthalimide, N-(trifluoromethylsulfonyloxy)-5-norbornene-2,3- dicarboxyimide, N-(trifluoromethylsulfonyloxy)naphthalimide, N-(10-camphorsulfonyloxy)naphthalimide, and the like.

The base generating agent as a radiation sensitive compound may be selected from various compounds which generate a base by irradiating a radiation on a resist composition containing such a compound. Specific examples thereof include 2-nitrobenzyl cyclohexylcarbamate, 2,6-dinotrobenzyl cyclohexylcarbamate, formanilide, triphenylsulfonium hydroxide and the like. These compounds decompose by the action of a radiation to form an amine, a hydroxyl anion or the like.

Furthermore, it is generally known that resist compositions of chemical amplification type using an acid generating agent deteriorate in performance due to inactivation of the acid by standing after irradiation with a radiation and that such deterioration can be suppressed by adding a basic nitrogen containing organic compound, particularly an amine or the like, as a quencher. Likewise, in the present invention, when an acid generating agent is used as a radiation sensitive compound, addition of such compound is preferred. Examples of basic compound used as a quencher include compounds represented by the following formulae:

26 R 14 R1 3 11 R 15 & N \ R 12 R" R 12 R" R 12 NI N N R 13 A R 13 4 -f ip R 14 R 15 R15 R14 R 13 R 14 C'N R11-ND R 15 12 R11-N/ N-R R11-N.' 0 R 16 -N R11 N 13 12 CrN R R I R" 14 R 13 R 13 14 14 R 13 R 13 14 R R \:-N N--j/-R N 12 wherein R" and R, which are same or dif f erent from each other, represent hydrogen, or alkyl, cycloalkyl or aryl which may be 13 14 15 optionally substituted with a hydroxyl; R, R and R, which are same or different from each other, represent hydrogen, or alkyl, cycloalkyl, aryl or alkoxy which may be optionally substituted with a hydroxyl; R 16 represents alkyl or cycloalkyl which may be optionally substituted with a hydroxyl; and A represents alkylene, carbonyl, imino, disulf ide, sulfide or a 16 secondary amine. The alkyl repres'ented by R" to R, the alkoxy represented by R 13 to R 15 may have about 1 to 6 carbon atoms. The cycloalkyl represented by R" to R 16 may have about 5 to 10 carbon atoms and the aryl represented by R" to R15 may have about 6 to 10 carbon atoms. The alkylene represented by A may have about 1 to 6 carbon atoms and may be straight-chained or branched.

Furthermore, the quencher may be a hindered amine compound having a piperidine basic structure as disclosed in JP-A-11-52575.

The resist composition of the present invention preferably contains the binder component in a range of about 60 to 99.9% by weight and the radiation sensitive compound in a range of about 0. 1 to 20-'.' by weight, based on the total solid amount. When a dissolution inhibitor is used, the dissolution inhibitor is included in the binder component defined in this invention. The amount of the dissolution inhibitor is preferably in a range of about 5 to 40-9. by weight, based on the total solid amount of the resist composition. In the case of a negative working resist, preferably it contains a cross- linking agent in a range of about 1 to 30% by weight, based on the total solid amount of the resist composition. In the case of a positive working resist containing a binder resin which becomes soluble in alkali by the action of a radiation sensitive compound after irradiation of a radiation, the amount of the binder resin is preferably about 80% by weight or more, based on the total amount of the binder resin and the radiation sensitive compound. When the radiation sensitive compound is an acid generating agent and a basic compound is used as a quencher, the amount of the quencher is preferably about 0. 0 1 to 1% by weight, based on the total solid amount of the resist composition. The composition can further comprise, if necess,ary, a small amount of various additives such as photo -,sensitizer, another resin, surfactant, stabilizer, dye and the like.

The resist composition of the invention is usually converted into a resist solution in which the above described components are dissolved in a solvent and applied onto a substrate such as a silicone wafer. The solvent used here may be anyone insofar as it dissolves the components, has a suitable drying rate and gives a uniform and smooth film after evaporation of the solvent, and those generally used in this f ield can be used. Examples of the solvent include glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate and propylene glycol monomethyl ether acetate; ethers such as diethylene glycol dimethyl ether; esters such as ethyl lactate, butyl acetate, amyl acetate and ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; cyclic esters such as y-butyrolactone and so on. These solvents can be used independently of each other or in combination of two or more.

The resist film formed by applying on a substrate and drying is subjected to exposure treatment for patterning, then to heat treatment for promoting protective group-cleaving reaction or cross-linking reaction and finally developed with an alkaline developer. The alkaline developer used here may be any aqueous alkaline solutions used in this field. Widely used developer is an aqueous solution of tetramethyl. ammonium hydroxide or (2-hydroxyethyl)trimethyl ammonium hydroxide (common name: choline).

The present invention will now be described in more specific based on Examples, which by no means should be construed as a limitation upon the scope of the invention. In Examples, parts are weight based unless otherwise specified. The weight average molecular weight and the molecular weight distribution, which is weight average molecular weight/ number average molecular weight are values obtained by gel permeation chromatography using polystyrene as the standard substance.

Synthetic Example 1 for Monomer (Synthesis of 2-methyl-2adamantyl methacrylate) Into a reaction vessel were charged 83.1 g of 2methyl-2-adamantanol and 101 g of triethylamine, and 200 g of methyl isobutyl ketone was added thereto to form a solution. To this solution was added dropwise 78.4 g (1.5 times by mole based on 2-methyl-2- adamantanol) of methacryloyl chloride.

The solution was stirred at room temperature for about 10 hours. Af ter f iltration, the organic layer was washed with 5% by weight aqueous sodium hydrogen carbonate solution and then washed twice with water. The organic layer was concentrated and distilled under reduced pressure to give 2methyl-2-adamantyl methacrylate represented by the following formula:

- CH3 CH3 CH2=U-U-U - 11 U Synthetic Example 2 for Monomer (Synthesis of a methacryloyloxy - y - butyro 1 act one) After charging 100 g of a-bromo-T-butyrolactone and 104.4 g (2.0 times by mole based on a-bromo-y-butyrolactone) of methacrylic acid, 300 g of isobutyl ketone was added thereto to form a solution. To this solution was added dropwise 183. 6 g (3.0 times by mole based on a-bromo-y-butyrolactone) of triethylamine. Then, the solution was stirred at room temperature for about 10 hours. After filtration, the organic layer was washed with 5% by weight aqueous sodium hydrogen carbonate solution and then washed twice with water. The organic layer was concentrated to give a-methacryloyloxy- y- butyrolactone represented by the following formula:

Y H3 CH2 =c- - 0 0 0 0 Synthetic Example for Resin (Al) Into a 100 ml three-necked f lask equipped with a magnetic stirrer, a cooler, a thermometer, a nitrogen introducer and a 20 dropping funnel were charged 5.81 g of 2-trifluoromethyl acrylate [obtained from Kanto Chemical], 9.72 g of 2methyl-2-adamantyl methacrylate and 10.5 g of methyl isobutyl ketone. After replacing the air in the vessel with nitrogen, the mixture was heated to 800C and a solution formed by dissolving 0.34 g of azobisisobutyronitrile in 10 g of methyl isobutyl ketone was added dropwise over 30 minutes. Then, the mixture was maintained for 8 hours keeping it at 800C. After cooling the obtained reaction solution to 300C, 7.5 g of triethylamine was added dropwise over 1 hour. Thereaf ter, 8. 56 g of cx-bromo-y-butyrolactone was added dropwise at 35 to 45 OC over 2 hours. The reaction was continued for 8 hours keeping it at 45"C. Then the solution was filtered and the filtrate was washed 6 times with water. The washed organic layer was concentrated, combined with 2-heptanone, concentrated and added dropwise to 65% aqueous methanol. The precipitated resin was filtered and dried to give the resin Al. Amount: 14.05 g.

Synthetic Example for Resin (A2) Into a 100 ml three-necked f lask equipped with a magnetic stirrer, a cooler, a thermometer, a nitrogen introducer and a dropping funnel were charged 15.54 g of t-butyl 5 norbornene-2-carboxylate, 7.84 g of maleic anhydride, 9.44 g of hexaf luoroisopropyl methacrylate and 22 g of methyl isobutyl ketone. After replacing the air in the vessel with nitrogen, the mixture was heated to 800C and a solution formed by dissolving 0.82 g of azobisisobutyronitr-ile in 11 g of methyl isobutyl ketone was added dropwise over 30 minutes. Then, the mixture was maintained for 8 hours keeping it at 800C. Thereafter, the reaction solution was poured into a mixed solution consisting of 250 g of methanol and 100 g of water.

The precipitated resin was dissolved in propylene glycol methyl ether acetate and concentrated to give a resin solution. Amount: 64.55 g. Solid content: 21.40%. This was referred to as the resin A2.

Synthetic Example for Resin (A3) Into a 100 ml three-necked flask equipped with a cooler, thermometer, a magnetic stirrer, a nitrogen introducer and dropping funnel were charged 8.59 g of 2-methyladamantyl bicyclo[2.2.llhept-5-ene-2-carboxylate (hereinafter, may be expressed as "NB-Mad"), 2.94 g of maleic anhydride (hereinafter, may be expressed as "MA"), 5.97 g of 3(perfluoro-3-methylbutyl)-2-hydroxypropyl acrylate (hereinafter, may be expressed as "TFMC700HAA") and 10 g of 4-methyl-2-pentanone. The air in the vessel was replaced with nitrogen. After heating the mixture to 800C, a 0.31 g of azobisisobutyronitrile dissolved in 7 g of 4-methyl-2pentanone was added dropwise over 30 minutes. Then, the mixture was maintained for 8 hours keeping it at 800C. After cooling, the reaction solution was poured into 300 ml of methanol and the precipitated resin was collected by f iltration. Vacuum drying at 400C for 8 hours gave 10. 2 g of a resin. Weight average molecular weight (Mw) converted to polystyrene: 6,400. This was referred to as the resin A3.

Synthetic Example for Resins (A4, A5 and Xl) According to similar procedures to the procedure in Synthetic Example f or Resin (A3), resins listed in the f ollowing Table were obtained:

Monomer composition charged MW Synthetic Example for Resin A4: NB-TB/MA/TFMC70HAA=40/40/20 6,100 Synthetic Example for Resin A5: NB-2Mad/MA/TFMC70HAA=45/45/10 5,500 Synthetic Example for Resin X1: NB-TB/MA=50/50 5,400 NB-TB: 2-methylpropyl bicyclo[2.2.11hept-5-ene2-carboxylate Synthetic Example for Resin (A6) Intoa 100 ml three-necked flask equipped with a cooler, a thermometer, a magnetic stirrer, a nitrogen introducer and a dropping funnel were charged 9.43 g of 2-adamantylpropyl bicyclo[2.2.llhept-5-ene-2-carboxylate (NB-AdTB), 2.94 g of maleic anhydride, 5.97 g of 3-(perfluoro-3-methylbutyl)-2 hydroxypropyl acrylate and 10 g of 4-methyl-2-pentanone. The air in the vessel was replaced with nitrogen. After heating the mixture to 800C, 0. 31 g of azobisisobutyronitrile dissolved in 7 g of 4-methyl-2-pentanone was added dropwise over 30 minutes. Then, the mixture was maintained for 8 hours keeping it at 800C. After cooling, the reaction solution was poured into 300 ml of hexane and the precipitated resin was collected by filtration. Vacuum drying at 400C for 8 hours gave 7.3 g of a resin. Weight average molecular weight (Mw) converted to polystyrene: 10,900. This was referred to as the resin A6.

Synthetic Example for Resin (M) The procedure in Synthetic Example for Resin A6 was repeated except that the molar ratio of the charged monomers was changed to NB- AdTB/MA/TFMC70HMA = 40/40/20 to give a resin. 5 Weight average molecular weight (Mw) converted to polystyrene: 16,700. This was referred to as the resin A7.

Synthetic Example for Resin (A8) Into a 100 ml three-necked flask equipped with a cooler, a thermometer, a magnetic stirrer, a nitrogen introducer and a dropping funnel were charged 7.03 g of 2-adamantyl methacrylate (hereinafter, may be expressed as "MadMA"), 12.37 g of (perfluoro-3-methylbutyl)-2-hydroxypropyl acrylate and 10 g of 4-methyl-2pentanone. The air in the vessel was replaced with nitrogen. Af ter heating the mixture to 800C, 0. 25 g of azobisisobutyronitrile dissolved in 7 g of 4-methyl-2pentanone was added dropwise over 30 minutes. Then, the mixture was maintained for 8 hours keeping it at 80.OC. After cooling, the reaction solution was poured into 300 ml of hexane and the precipitated resin was collected by filtration. Vacuum drying at 4 OOC f or 8 hours gave 10. 5 g of a resin. Weight average molecular weight (Mw) converted to polystyrene: 24, 000. This was referred to as the resin A8.

Synthetic Example for Resin (X2) After charging 2-methyl-2-adamantyl methacrylate and a-methacryloyloxy-y- butyrolactone in a molar ratio of 5: 5 (15. 0 g/ 11. 7 g), methyl ethyl ketone in twice by weight of total monomers was added to form a solution. Then, azobisisobutyronitrile in 2% by mole based on the amount of total monomers was added as an initiator and the solution was heated to 8 OOC for about 8 hours. Thereafter, purification was effected by pouring the reaction solution into a large quantity of heptane and this operation was carried out 3 times in total. As the result, a copolymer having a weight average molecular weight of about 10, 000 was obtained. This was referred to as the resin X2.

Examples 1 to 8 and Comparative Examples 1 and 2 Components listed below were mixed and filtered through a fluorine resin filter having a pore diameter of 0. 2 pn to give resist solutions.

Resin 10 parts Acid generating agent:

p-tolyldiphenylsulfonium trifluoromethanesulfonate 0.2 part ("MDS-205", obtained from Midori Chemical) Quencher: 2,6-diidopropyl aniline 0.015 part Solvent: propylene glycol monomethyl ether acetate parts The resist solutions prepared as above were coated on silicon wafers which had been treated with hexamethylsilazane at 230C for 20 seconds so that the film thickness after drying was 0.1 [tm. The prebake was carried out under conditions of 1200C for 60 seconds on a direct hot plate. The wafers having a resist film formed in such manner were exposed with a simplified F2 excimer laser exposure apparatus ["VUVES-4500" obtained from Lithotec Japan] through an open frame, changing stepwise the amount of exposure. After exposure, the wafers were subjected to post-exposure bake (PEB) cat a temperature of 12 OOC f or 6 0 seconds on a hot plate and then to paddle development in 2. 385.1 aqueous tetramethylammonium hydroxide solution for 60 seconds. Wafers obtained after development were assessed by visual observation and the minimum exposure at which the resist f ilm dropped (f ilm- dropping sensitivity) was determined to give the results shown in Table 1.

On other hand, each of the resist solutions prepared as above and solutions obtained by dissolving each of the resins alone in propylene glycol monomethyl ether acetate was coated on a magnesium fluoride waf er so that the film thickness af ter drying was 0. 1 pn. The prebake was carried out under conditions of 120'C for 60 seconds on a direct hot plate to form resist films. The resist films formed in such manner were assessed for transmittance at a wavelength of 157 nm using the transmittance - measurement ability of the simplified F2 excimer laser exposure apparatus used above to give the results shown in Table 1.

37 Table 1

Resin Film-dropping Transmittance sensitivity Resin only Resist Example 1 Al 2 Mj/CM2 35-9. 35-5.1 Example 2 A2 5 Mj/CM2 36-0. 33% Example 3 A3 3 Mj/CM2 32-0o 30-0.

Example 4 A4 4.5 Mj/CM2 38% 365'.1 Example 5 A5 4 Mj/CM2 28% 26% Example 6 A6 2.5 Mj/CM2 33% 31% Example 7 A7 3.5 Mj/CM2 30% 30-0.

Example 8 A8 1 Mj/CM2 44% 43-0.

Comparative Example 1 X1 8 Mj/CM2 26% 25% Comparative Example 1 X2 3 Mj/CM2 25% 25% Synthetic Example for Resin (A9) Into a 100 ml flask equipped with a magnetic stirrer, 5 a cooler, a thermometer, a nitrogen introducer and a dropping funnel were charged 10. 31 g of 3-perfluoro-3-methylbutyl)- 2-hydroxypropyl methacrylate [obtained from Daikin Kaseihin Hanbaij, 17. 63 g of p-t-butoxystyrene and 31 g of methyl isobutyl ketone. After replacing the air in the vessel with 10 nitrogen, the mixture was heated to 800C and a solution formed by dissolving 0. 82 g of az obi s isobutyronit rile in 11 g of methyl isobutyl ketone was added dropwise over 30 minutes. Then, the mixture was maintained for 8 hours keeping it at 800C. Then the solution was poured into a mixed solution consisting of 250 g of methanol and 100 g of water. The precipitated resin was dissolved in methyl isobutyl ketone and concentrated to give 57. 6 g of a resin solution. To this resin solution were added 62.8 g of methyl isobutyl ketone, 3.0 g of p-toluenesulfonic acid and 9.7 g of water and heated at 700C for 15 hours. The obtained reaction solution was washed 5 times with water and concentrated. Then, 300 g of propylene glycol methyl ether acetate was added and concentration was continued to give a resin solution. Amount: 65.3 g. Solid content: 27.21%.

Weight average molecular weight: 14, 900. This was referred to as the resin A9.

Synthetic Example for Resin (A10) Into a 200 ml flask equipped with a magnetic stirrer, a cooler, a thermometer, a nitrogen introducer and a dropping funnel was charged 26.81 g of methyl isobutyl ketone. After replacing the air in the vessel with nitrogen, the mixture was heated to 840C and a solution formed separately by dissolving 9.89 g of 3-perfluoro-3- methylbutyl)-2-hydroxypropyl methacrylate [obtained from Daikin Kaseihin Hanbail, 16. 92 g of p-t-butoxystyrene and 1.97 g of azobisisobutyronitrile in 26. 81 g of methyl isobutyl ketone was added dropwise over 1 hour.

Then, the mixture was maintained for 8 hours keeping it at 84 OC. The reaction solution was poured into a mixed solution consisting of 247.23 g of methanol and 123.61 g of water over 25 30 minutes. The obtained resin was dissolved in methyl isobutyl ketone and concentrated to give 67.03 g of a resin solution.

To this resin solution were added 93.52 g of methyl 39 - isobutyl ketone, 3.49 g of p-toluenesulfonic acid and 11.26 g of water and heated at 700C for 15 hours. The obtained reaction solution was washed 5 times with water, concentrated and then added dropwise to 446.88 g of n-heptane over 30 minutes. The obtained resin was f iltereaand vacuum- dried to give the product resin. Amount: 17.07 g. Weight average molecular weight:

4,400. This was referred to as the resin AIO.

Resin X3: a resin obtained by protecting hydroxyl groups in poly (p-vinylphenol) (commercial name: "VP-2500", manufactured by Nippon Soda) with isopropyl group at an average protection rate of 20%.

Examples 9 and 10 and Comparative Example 3 Components, listed below, were mixed and filtered through a fluorine resin filter having a pore diameter of 0.2 tm to give resist solutions.

Resin (as solid content) 10 parts Cross-linking agent: hexamethoxymethyl melamine 0.5 part Acid generating agent: N-(isopropylsulfonyloxy)succinimide 1.1 part Quencher: 1,3-di(4-pyridyl)propane 0.0125 part Solvent (including solvent derived from the resin solution): propylene glycol monomethyl ether acetate parts An organic reflection-preventing membrane having a thickness of 600 angstrom, which was prepared by applying a composition "DUV-42" for organic reflection-preventing membrane, manufactured by Brewer, and baking under conditions of 2150C for 60 seconds, was formed on a silicon wafer. The resist solution obtained above was applied on said wafer with a spin coater so that the film thickness after drying was 0.523 pn. After applying the resist solution, the wafer was pre baked on a direct hotplate under conditions of 100'C for 60 seconds. The wafer having a resist film formed thereon was irradiated with a KrF eximer stepper ["NSR-2205 EX12B", manufactured by Nikon, NA = 0.55, a = 0.81 through a line and- space pattern, changing stepwise the exposure amount. The exposed wafer was subjected to post-exposure baking (PEB) on a hot plate under conditions of 1050C for 60 seconds. Then the wafer was subjected to paddle development with 2. 38% by weight aqueous tetramethyl ammonium hydroxide solution f or 6 0 seconds.

The developed line-and-space pattern was observed bya scanning electron microscope and assessed for the effective sensitivity 20- and the resolution by the following methods:

Effective sensitivity: This is expressed in the minimum amount of exposure which gave 1: 1 line-and-space pattern of 0.20 p-m.

Resolution: This is expressed in the minimum size which gave line-and-space pattern spitted at the exposure amount of the effective sensitivity.

_ 41 The resist solutions prepared as above and solutions obtained by dissolving the resin alone in propylene glycol monomethyl ether acetate were coated on magnesium fluoride waf ers so that the f ilm thickness af ter drying was 0. 1 pn. The prebake was carried out under conditions of 100'C f or 60 seconds on a direct hot plate to form resist films. The resist films formed in such manner were assessed for transmittance at a wavelength of 157 nm using the transmittance-measurement ability of the simplified F2 excimer laser exposure apparatus ("VUVES-4500", manufactured by Lithotec Japan) to give the results shown in Table 2.

Table 2

Synthetic Example for Resin (All) Into a four-necked flask equipped with a magnetic stirrer, a nitrogen introducer, a Dimroth condenser, a thermometer and a dropping funnel were charged 9.37 g of 2methyl-2-adamantyl methacrylate, 9.44 g of 1trifluoromethyl-2,2,2-trifluoroethyl methacrylate [obtained from Tokyo Kasei Industries], 0.263 g of azobisisobutyronitrile and 40.9 g of methyl isobutyl ketone. The air in the vessel was replaced with nitrogen. Then, f lowing Resin Effective Resolution Transmittance sensitivity (KrF) Resin Resist (KrF) only Example 9 A9 40% 4 0 P6 18 Mj/CM2 0. 16 Lm Example 10 A10 39% 38% go Mj/CM2 0. 15 lim Comparative X3 27-0. 27-0. 27 Mj/CM2 0.16 pn Example 3 nitrogen stream in the system, the mixture was heated to 80 OC with an oil bath and maintained the temperature f or about 7 hours. After cooling, the reaction solution was poured into 1 dM3 of methanol with stirring. Af ter continuing the stirring f or 30 minutes, the solution was f iltered to give 25. 8 g of white powders. The white powders were dried under reduced pressure at 600C for about 6 hours to give 8. 4 g of a resin. Yield: 45%. Weight average molecular weight: 10, 200. This was referred to as the resin All.

Examples 11 and Comparative Example 4 Components listed below were mixed and filtered through a fluorine resin filter having a pore diameter of 0. 2 [tm. to give resist solutions.

Resin (as solid content) 10 parts Acid generating agent:

p-tolyldiphenylsulfonium trifluoromethanesulfonate ("MDS-205", obtained from Midori Chemicals) 0.2 part Quencher: dicyclohexylmethylamine 0.015 part Solvent: 100 parts Example: 2-heptanone Comparative Example: propylene glycol monomethyl ether acetate /y-butyrolactone (95/5) An organic reflection-preventing membrane having a thickness of 1,600 angstrom, which was prepared by applying a composition "DUV-30J-14" for organic reflection-preventing membrane, manufactured by Brewer, and baking under conditions of 2150C for 60 seconds, was formed on a silicon wafer. The resist solution obtained above was applied on said wafer with a spin coater so that the film thickness after drying was 0.39 pn. After applying the resist solution, the wafer was prebaked on a direct hotplate under conditions of 1200C for 60 seconds. The wafer having a resist film formed thereon was irradiated with an ArF eximer stepper " NSR ArF ", manufactured by Nikon, NA = 0.55, cy = 0.6] through a line-and-space pattern, changing stepwise the exposure amount. The exposed wafer was subjected to post-exposure baking (PEB) on a hot plate under conditions of 1200C for 60 seconds. Then the wafer was subjected to paddle development with 2.38% by weight aqueous tetramethyl ammonium hydroxide solution for 60 seconds. The developed line-and-space pattern was observed by a scanning electron microscope and the effective sensitivity and the resolution were assessed by the following methods:

Effective sensitivity: This is expressed in the minimum 20 amount of exposure which gave 1: 1 line-and-space pattern of 0.18 =.

Resolution: This is expressed in the minimum size which gave line-andspace pattern spitted at the exposure amount of the effective sensitivity.

The resist solutions prepared as above and solutions obtained by dissolving the resin alone in propylene glycol monomethyl ether acetate were coated on magnesium fluoride waf ers so that the f ilm thickness af ter drying was 0. 1 Lm. The prebake was carried out under conditions of 1200C for 60 seconds on a direct hot plate to form resist films. The resist films formed in such manner were assessed for transmittance at a wavelength of 157 nm using the transmittance-measurement ability of the simplified F2 excimer laser exposure apparatus ("VUVES-4500", manufactured by Lithotec Japan) to give the results shown in Table 3.

Table 3

Synthetic Example for Resin (A12) Into a 100 ml flask equipped with a stirrer, a cooler, a thermometer and a nitrogen introducer were charged 9. 73 g of p-acetoxystyrene, 2.56 g of t-butyl acrylate, 7.96 g of 3 (perfluoro-3-methylbutyl)-2-hydroxypropyl methacrylate [obtained from Daikin Industries Co. Ltd.], and 13.51 g of isopropyl alcohol. After replacing the air in the vessel with nitrogen, the mixture was heated to 800C and a solution formed by dissolving 0.41 g of azobisisobutyronitrile in 6.75 g of isopropyl alcohol was added dropwise over 30 minutes. Then, the mixture was maintained for 6 hours keeping it at 800C.

Thereafter, the reaction mixture was poured into a mixed solution of methanol and water to precipitate the resin which Resin Effective Resolution Transmittance sensitivity Resin Resist only Example 11 All 30% 30% 42 Mj/CM2 0.16 pm Comparative X2 25% 25% 36 Mj/CM2 0.16 Vm Example 4 was then filtered and dried to give 15.69 g of resin.

Into a 100 ml flask equipped with a stirrer, a cooler, a thermometer and a nitrogen introducer were charged 15.69 g of the resin obtained above, 1.57 g of 4-dimethylaminopyridine and 47.07 g of methanol, and the mixture was kept for 15 hours under reflux. Then, after cooling, the mixture was neutralized with 0.93 g of glacial acetic acid. The neutralized mixture was charged to 784. 50 g of water to precipitate the resin which was then filtered to obtain a resin crystal. The resin crystal was dissolved in acetone and the obtained solution was charged to water to precipitate the resin which was then filtered to obtain a resin crystal, and this operation is repeated three times. Then, the crystal thus obtained was dried to obtain 12.59 g of resin. The weight average molecular weight was 37,000 and the molecular weight distiribution was 3.72.

Hereinafter, this resin is expressed as "Resin A 12".

Synthetic Example for Resin (A13) Into a 100 ml flask equipped with a stirrer, a cooler, a thermometer and a nitrogen introducer were charged 9. 73 g of p- acetoxystyrene, 4.69 g of 2-methyl-2-adamantyl methacrylate, 7.96 g of 3- (perfluoro-3-methylbutyl)-2-hydroxypropyl methacrylate [obtained from Daikin Industries Co. Ltd. and 13.9.2 g of isopropyl alcohol. After replacing the air in the vessel with nitrogen, the mixture was heated to 800C and a solution formed by dissolving 0. 41 g of azobisisobutyronitrile, in 7. 46 g of isopropyl alcohol was added dropwise over 30 minutes. Then, the mixture was maintained for 6 hours keeping it at 80 OC. Thereafter, the reaction mixture was poured into a mixed solution of methanol and water to precipitate the resin which was then filtered and dried to give 22.08 g of resin.

Into a 300 ml flask equipped with a stirrer, a cooler, a thermometer and a nitrogen introducer were charged 22.08 g of the resin obtained above, 2.21 g of 4 -dime thyl aminopyridine and 110 g of methanol, and the mixture was kept for 15 hours under ref lux. Then, af ter cooling, the mixture was neutralized with 2.21 g of glacial acetic acid. The neutralized mixture was charged to 2000 g of water to precipitate the resin which was then filtered to obtain a resin crystal. The resin crystal was dissolved in acetone and the obtained solution was charged to water to precipitate the resin which was then filtered to obtain a resin crystal, and this operation is repeated three times. Then, the crystal thus obtained was dried to obtain 11.51 g of resin. The weight average molecular weight was 30,900 and the molecular weight distiribution was 1.99. Hereinafter, this resin is expressed as "Resin A 13".

Resin X4 TSM-4, a terpolymer of t-butylacrylate, styrene and p-hydroxystyrene manufactured by Maruzen Petrochemical Co., Ltd., is hereinafter expressed as "Resin X4". The polymerization ratio of t-butylacrylate, styrene and p- hydroxystyrene in Resin X4 was measured with a nuclear magnetic resonance (13C -NMR) spectrometer, and it is about 20/20/60.

Synthetic Example for Resin (X5) (1) Into a flask were charged 39.7 g (0.245 mol) of p acetoxystyrene, 24.6 g (0.105 mol) of 2-methyl-2-adamantyl me thacryl ate and 128.6 g of is opropyl alcohol. After rep lac in g the air in the vessel with nitrogen, the mixture was heated to 750C and a solution formed by dissolving 4.84 g (0.021 mol) of dimethyl 2,2-azobis(2-methylpropionate) in 97 g of isopropyl alcohol was added dropwise. Then, the mixture was maintained for 30 minutes at 750C, and for 11 hours under reflux.

Thereafter, the reaction mixture was diluted with aceton.e and the obtained solution was charged to heptane to precipitate the resin which was then filtered. The resin obtained by the filtration was dried to give 54.1 g of crystal of copolymer of p-acetoxystyrene and 2-methyl-2adamantyl methacrylate. (2) Into a flask were charged 53.2 g of the copolymer of p- acetoxystyrene and 2-methyl-2-adamantyl methacrylate, 5.3 g (0. 043 mol) of 4 -dime thylaminopyridine and 159. 5 g of methanol, and the mixture was kept f or 2 0 hours under ref lux. Then, af ter cooling, the mixture was neutralized with 3.92 g (0.065 mol) of glacial acetic acid. The neutralized mixture was charged to water to precipitate the resin which was then filtered to obtain a resin crystal. The resin crystal was dissolved in acetone and the obtained solution was charged to water to precipitate the resin which was then filtered to obtain a resin crystal, and this operation is repeated three times. Then, the crystal thus obtained was dried to give 41.2 g of crystal of copolymer of p-hydroxystyrene and 2-methyl-2-adamantyl methacrylate. The weight average molecular weight was 8,100 and the molecular weight distiribution was 1.68. The polymerization ratio of p-acetoxystyrene and 2-methyl-2adamantyl methacrylate was measured with a nuclear magnetic resonance ( 13C -NMR) spectrometer, and it is about 70/30.

Hereinafter, this resin is expressed as "Resin X5".

Synthetic Example for Resin (X6) (1) Into a flask were charged 45.4 g (0. 28 mol) of pacetoxystyrene, 16.4 g (0.07 mol) of 2-methyl-2-adamantyl methacrylate and 123. 6 g of isopropyl alcohol. Af ter replacing the air in the vessel with nitrogen, the mixture was heated to 750C and a solution formed by dissolving 4.84 g (0.021 mol) of dimethyl 2,2-azobis(2methylpropionate) in 9.7 g of 1sopropyl alcohol was added dropwise. Then, the mixture was maintained for 30 minutes at 750C, and for 11 hours under reflux.

Thereafter, the reaction mixture was diluted with acetone and the obtained solution was charged to heptane to precipitate the resin which was then filtered. The resin obtained by the filtration was dried to give 54. 2 g of crystal of copolymer of p- acetoxystyrene and 2-methyl-2-adamantyl methacrylate.

(2) Into a flask were charged 53.0 g of the copolymer of pacetoxystyrene and 2-methyl-2-adamantyl methacrylate, 5.3 g (0. 043 mol) of 4dimethylaminopyridine and 159. 0 g of methanol, and the mixture was kept f or 20 hours under ref lux. Then, af ter cooling, the mixture was neutralized with 3.13 g (0.052 mol) of glacial acetic acid. The neutralized mixture was charged to water to precipitate the resin which was then filtered to obtain a resin crystal. The resin crystal was dissolved in acetone and the obtained solution was charged to water to precipitate the resin which was then filtered to obtain a resin crystal, and this operation is repeated three times. Then, the crystal thus obtained was dried to give 37.8 g of crystal of copolymer of phydroxystyrene and 2-methyl-2-adamantyl methacrylate. The weight average molecular weight was about 7,900 and the molecular weight distiribution was 1.72. The polymerization ratio of p- acetoxystyrene and 2-methyl-2adamantyl methacrylate was measured with a nuclear magnetic resonance ( 13C -NMR) spectrometer, and it is about 80/20.

Hereinafter, this resin is expressed as "Resin XV.

Example 12 and Comparative Example 5 Components listed below were mixed and f Iltered through a f luorine resin f ilter having a pore diameter of 0. 2 [un to give resist solutions.

Resin 10 parts Acid generating agent:

bis(4-tert-butylphenyl)iodonium camphor sulfonate 0.52 part Quencher: tripropanol amine 0.052 part Solvent: ethyl lactate 100 parts Example 13 and Comparative Example 6 Components listed below were mixed and filtered through a fluorine resin filter having a pore diameter of 0. 2 pm to give resist solutions.

Resin 10 parts Acid generating agent:

bis(4-tert-butylphenyl)iodonium camphor sulfonate 0.52 part Quencher: 2,6-diisopropyl aniline 0.052 part Solvent: methyl amyl ketone 100 parts The resist solutions prepared as above were coated on silicon wafers which had been treated with hexamethylsilazane, at 230C for 20 seconds so that the film thickness after drying was 0.1 pin. The prebake was carried out under conditions of 1300C for 60 seconds on a direct hot plate. The wafers having a resist film formed in such manner were exposed with a simplified F2 excimer laser exposure apparatus ["VUVES-4500" obtained from Lithotec Japan] through an open frame, changing stepwise the amount of exposure. After exposure, the wafers were subjected to post- exposure bake (PEB) at a temperature of 1400C f or 60 seconds on a hot plate and then to paddle development in 2. 38-9. aqueous tetramethylammonium hydroxide solution f or 60 seconds. Wafers obtained after development were assessed by visual observation and the minimum exposure at which the resist f ilm dropped (f ilm-dropping sensitivity) was determined to give the results shown in Table 4.

On other hand, each of the resist solutions prepared as above and solutions obtained by dissolving each of the resins alone in propylene glycol monomethyl ether acetate was coated on a magnesium fluoride waf er so that the f ilm thickness af ter drying was 0. 1 Lm. The prebake was carried out under conditions of 1300C for 60 seconds on a direct hot plate to form resist films. The resist films formed in such manner were assessed for transmittance at a wavelength of 157 nm using a vacuum ultra-violet spectrometer (VUV-200, manufactured by JASCO 5 Corporation) to give the results shown in Table 4.

Table 4

Resin Film-dropping Transmittance sensitivity Resin only Resist Example 12 A12 2.5 Mj/CM2 30% 31% Example 13 A13 0.5 Mj/CM2 27% 27-W Comparative Example 5 X4 2 Mj/CM2 24% 25% Comparative Example 6 X5/X6=1 3 Mj/CM2 21% 22% The resist composition of the present invention exhibits a high transmittance in a light exposure using a light source having a wavelength of 170 nm or less, for example, F2 excimer laser at 157 nm. The resist composition also exhibits a high resolution in KrF or ArF light exposure and has a sufficient contrast. Therefore, the resist composition can exhibit an excellent performance as a resist of chemical amplification type using a light source having a wavelength of 170 nm or less.

52

Claims

I A chernical amplification type resist composition comprising a radiation sensitive compound; and a binder resin which is soluble in alkali by itself or becomes soluble in alkali by a chernical change caused by the action of the radiation sensitive compound after irradiation, and has a polymerization unit derived frorn a monomer of formula (1):

U wherein Q represents hydrogen, methyl or a fluoroalkyl having I to 4 carbon atorris; R' represents an alkyl having I to 14 carbon atoms which may be optionally substituted with halogen, hydroxyl or alicyclic ring, or an alicyclic or lactone ring which may be optionally Substituted with halogen, hydroxyl or alkyl; provided that at least one of Q and R' has at least one fluorine atom.
2. A composition according to claim I wherein Q is a trifluoromethyl group.
3. A composition according to claim I to 2 wherein R' is a fluoroalkyl having I to 14 carbon atoms which is Substituted with at least one fluorine and which may be optionally substituted with a hydroxyl group.
4. A composition according to claim 3 wherein the fluoroalkyl having I to 14 carbon atoms which is substituted with at least one fluorine and which may be optionally substituted with a hydroxyl group is of formula (II):

OH R 2 1 1 3 CH2CH nn CH-R wherein R 2 represents hydrogen, an alkyl or a fluoroalkyl, R' represents a fluoroalkyl, the total number of carbon atoms in R 2 and R' is I to 11, and n represents 0 or 1.

ing to any one of clairns I to 4 which is of positive type A composition accordi and wherein the radiation sensitive compound is an active agent which generates an a'd oi I el a base by the action of radiation. 6. A composition according to claim 5, wherein the binder rtsin has a protective group cleavable by the action of an acid or a base, and is insoluble or difficultly soluble in alkali but becomes soluble in alkali after said protective group is cleaved by the action of an acid or a base. 7. A composition according to clairn 5 or 6, wherein the binder resin has 8 unit derived fi-om a 2-alkyl-2-adaniantyl (1-neth)acrylate of formula (111):

R R 4 CH2=U-U-U11 U wherein R represents hydrogen, methyl or a fluoroalkyl having I to 4 carbon atoms, and R 4 represents an alkyl, in addition to the polymerization unit derived from the monomer of formula (I),- and the radiation sensitive compound is an acid generating agent which generates an acid by the action of radiation.

A composition according to any one of claims 5 to 7, wherein the binder resin has an alicyclic olefin unit of formula (IV):

IV) tRPFR 6) wherein R' and R', which are the same as or different from each other, represent hydrogen, an alkyl having I to 3 carbon atoms, a hydroxyalkyl having I to 3 carbon atoms, carboxyl, cyano or a group -COOR' wherein R' is an alcohol residue, or R' and R' together form a carboxylic acid arihydride residue -C(=O)OC(=O)-, and an unsaturated dicarboxylic acid anhydride unit selected from i- naleic anhydride and itaconic anhydride, in addition to the polymerization unit derived from the monomer of formula (1). 9. A composition according to any one of claims I to 4 wherein the binder resin is soluble in alkali, and which is of negative type and con-1prises a cross-linking agent in addition to the binder resin and the radiation sensitive coinponent. 10. A composition according to claim I substantially as hereinbefore described in any one of Examples I to 13.