Chemically amplified positive type resist composition and sulfonate

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a chemically amplified positive resist composition used for microfabrication of semiconductors and a novel compound useful as an acid generator thereof.

【0002】

[Conventional technology]

A lithography process using a resist composition is usually used for microfabrication of semiconductors, and in lithography, the exposure wavelength is short in principle, as expressed by Rayleigh's diffraction-limited equation. It is possible to increase the resolution. The exposure light sources for lithography used in the manufacture of semiconductors are g-rays with a wavelength of 436 nm, i-lines with a wavelength of 365 nm, and KrF excimer lasers with a wavelength of 248 nm. The ArF excimer laser is seen as promising, and some such ArF excimer laser exposure resists are being put into practical use.

【0003】

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

【0004】

The resin used for the resist for ArF excimer laser exposure should not have an aromatic ring in order to secure the transmittance of the resist, and should have an alicyclic ring instead of an aromatic ring in order to have dry etching resistance. It is known. As such resins, various resins as described in DC Hofer, J. Photopolym. Sci. Technol., Vol.9, No.3, 387-398 (1996) are known. Also, S. Takechiet al., J. Photopolym. Sci. In Technol., Vol.9, No.3, 475-487 (1996) and JP-A-9-73173, a polymer or copolymer of 2-methyl-2-adamantyl methacrylate is used as a chemically amplified resist. When used as a resin, 2-methyl-2-adamantyl is cleaved by the action of acid and acts in a positive form, and high dry etching resistance, high resolution and good adhesion to a substrate are obtained. It is reported that it will be done. Further, in JP-A-10-274852, the adhesiveness to the substrate is improved by using a resin constituting the chemically amplified positive resist composition having a butyrolactone residue as a part of the polymerization unit. Japanese Patent Application Laid-Open No. 10-319595 describes a resist composition using a resin having a γ-butyrolactone-3-yl residue as a protecting group for a carboxyl group.

【0005】

By the way, since the chemically amplified resist utilizes the action of an acid, there is a problem that when the substrate is basic, the acid is deactivated and the profile becomes a tailed shape. It is known that a large amount of basic quencher substances should be added to solve this problem. However, if a large amount of quencher substance is added, the sensitivity of the resist decreases. Further, in ArF exposure, a resist is often applied on a substrate having low reflectance such as an organic or inorganic antireflection film. Although the use of such a low reflectance substrate is effective in improving the uniformity of dimensions, generally speaking, the profile of the resist becomes tapered due to light absorption and deteriorates.

【0006】

It is conceivable to reduce the amount of acid generator in the resist composition in order to reduce light absorption, but in this case the sensitivity is generally slowed down. As another method for reducing light absorption, transparency as described in JP-A-7-25846, JP-A-7-28237, JP-A-7-92675 and JP-A-8-27102. It is conceivable to use an aliphatic sulfonium salt having a high content. However, these known aliphatic sulfonium salts do not solve the problem that sufficient resolution cannot be obtained and the profile on the basic substrate has a tailed shape. As described above, the chemically amplified resist using a conventionally known acid generator has a problem that the performance, particularly the profile, changes depending on the type of the substrate.

【0007】

[Problems to be Solved by the Invention]

One of the objects of the present invention is chemical amplification which contains a resin component and an acid generator and is suitable for excimer laser lithography such as ArF and KrF, particularly light having a wavelength of 220 nm or less, for example, lithography using ArF excimer laser light. It is a type positive resist composition, which has good resist performance such as sensitivity, resolution, and adhesion to a substrate, and has little substrate dependence even when applied to a basic substrate or a low reflectance substrate. It is an object of the present invention to provide one that gives a good profile to any substrate.

【0008】

Another object of the present invention is to provide a compound useful as an acid generator of such a chemically amplified positive resist composition.

【0009】

The present inventors have improved the resolution by using a certain type of acid generator in combination, or by using an acid generator having a specific structure, and also a basic substrate or low reflectance. We have found that the profile of the rate substrate is also improved, and have completed the present invention.

【0010】

[Means for solving problems]

That is, from the first point of view, the present invention uses the following formula (I) as an acid generator. [0011]

<img file="JP2001192569A_D0001.tif" />【0012】

(During the formula, Q¹Represents alkyl, Q²Represents an alkyl or alicyclic hydrocarbon residue, m represents an integer of 1 to 8), an aliphatic sulfonium salt represented by the following formula (IIa), a triphenyl sulfonyum salt represented by the following formula (IIa), and the following formula ( Diphenyliodonium salt represented by IIb) [0013]

<img file="JP2001192569A_D0002.tif" />【0014】

(During the formula, Q³ , Q⁴, Q⁵, Q⁶ And Q⁷ Represents hydrogen, hydroxyl groups, alkyls with 1 to 6 carbon atoms or alkoxys with 1 to 6 carbon atoms, and q and p represent integers from 4 to 8) with at least one onium salt selected from each other. It has an acid generator and a polymerization unit having an acid-unstable group, and is characterized by containing a resin that is insoluble or sparingly soluble in alkali, but becomes soluble in alkali by the action of acid. Provided is a chemically amplified positive type resist composition.

【0015】

Among the aliphatic sulfonium salts represented by the above formula (I), those having a large carbon number with m of 4 to 8 in the sulfonate anion moiety have a remarkable effect of improving the resolution and profile, and this is used as an acid generator. Even when the compounds are used alone, they give excellent resolution and profile. Therefore, from the second point of view, the present invention also uses the following formula (Ia) as an acid generator. [0016]

<img file="JP2001192569A_D0003.tif" />【0017】

(During the formula, Q¹ And Q² Is as defined above, n represents an integer from 4 to 8), contains an aliphatic sulfonium salt, has a polymerization unit with an acid-unstable group, and is itself alkaline. Also provided is a chemically amplified positive resist composition containing a resin that is insoluble or sparingly soluble in, but is soluble in alkali by the action of an acid. Of course, even when an aliphatic sulfonium salt represented by the formula (Ia) having a large number of carbon atoms in the sulfonate anion moiety is used, at least one onium salt selected from the above formulas (IIa) and (IIb) should be used in combination. Is even more effective.

【0018】

The aliphatic sulfonium salt represented by the above formula (Ia) having a large number of carbon atoms in the sulfonate anion moiety is a compound not described in the literature. Therefore, the present invention also provides a sulfonium salt represented by the above formula (Ia) from a third point of view.

【0019】

BEST MODE FOR CARRYING OUT THE INVENTION

The acid generator used in the chemically amplified resist composition decomposes the substance by applying radiation such as light or electron beam to the substance itself or the resist composition containing the substance. Is generated. In the composition specified from the first viewpoint in the present invention, as such an acid generator, the aliphatic sulfonium salt represented by the formula (I), the triphenylsulfonium salt represented by the formula (IIa) and the above formula ( In the composition specified in combination with at least one onium salt selected from the diphenyliodonium salt represented by IIb) and specified from the second viewpoint, the sulfonate anion moiety has a large number of carbon atoms in the above formula (Ia). The aliphatic sulfonium salt indicated by is used.

【0020】

In equations (I) and (Ia), Q¹ Is alkyl and Q² Is an alkyl or alicyclic hydrocarbon residue. The alkyl in this case can have, for example, about 1 to 8 carbon atoms, and when it has 3 or more carbon atoms, it may be linear or branched. Specific examples of alkyl include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl and the like. Meanwhile, Q² The alicyclic hydrocarbon residue represented by can have, for example, about 5 to 16 carbon atoms, and can be of monocyclic cycloalkyl such as cyclopentyl, cyclohexyl and cyclooctyl, as well as norbornyl, isobornyl and adamantyl. It may be a group of such crosslinked polycycles. Further, in the formula (I), m representing the carbon number of the alkane moiety constituting the perfluoroalkane sulfonate anion is an integer of 1 to 8. Specific examples corresponding to the perfluoroalkanesulfonate anion in the formula (I) include trifluoromethanesulfonate ion, perfluorobutane sulfonate ion, perfluorooctane sulfonate ion and the like.

【0021】

Since each group constituting the sulfonium cation is non-aromatic, the aliphatic sulfonium salt represented by the formula (I) has a transmittance for light having a wavelength of 220 nm or less, for example, ArF excimer laser light having a wavelength of 193 nm. Is high. Therefore, by using such an aliphatic sulfonium salt as an acid generator, the resist composition containing the aliphatic sulfonium salt absorbs the exposure light having a short wavelength as described above at a reduced rate, and the profile becomes tapered. Can be prevented.

【0022】

However, in the formula (I), when the number of carbon atoms in the perfluoroalkanesulfonate anion moiety is small, for example, in the case of a trifluoromethanesulfonate anion, a resist composition using it alone as an acid generator can obtain sufficient resolution. In addition to being difficult to obtain, it is difficult to obtain a good profile, especially on a basic substrate. Therefore, in the resist composition specified from the first viewpoint in the present invention, at least one onium selected from the formulas (IIa) and (IIb) is used as the acid generator together with the aliphatic sulfonium salt of the formula (I). Salt is also used. By using such a sulfonium salt-based acid generator in combination, the resolution can be increased without impairing the substrate dependence as compared with the case where the aliphatic sulfonium salt-based acid generator of the formula (I) is used alone. Compared with the case where at least one onium salt-based acid generator selected from the formulas (IIa) and (IIb) is used alone, the sensitivity can be increased without impairing the substrate dependence.

【0023】

On the other hand, in the formula (I), when the number of carbon atoms in the perfluoroalkanesulfonate anion moiety increases, and specifically, when m in the formula (I) becomes 4 or more, the resist is used even when this is used alone as an acid generator. The resolution of the is improved, and the profile on the basic substrate and the low reflectance substrate is also improved. Therefore, in the resist composition specified from the second viewpoint in the present invention, as the acid generator, a compound having m of 4 or more in the formula (I), in other words, an aliphatic represented by the formula (Ia). Use a sulfonium salt. The reason why such a sulfonium salt having a perfluoroalkanesulfonate anion having a large number of carbon atoms is effective in improving the resolution of the resist and the profile on the basic substrate or the low reflectance substrate is not always clear. As the anions become bulky, the diffusion distance of the generated acid in the resist is shortened, and the distribution of the acid that is more faithful to the optical image is achieved, so that the resolution is improved and the low reflectance substrate is used. It is presumed that the profile in will be improved. Further, since the diffusion distance of the acid in the resist is shortened, the diffusion of the base from the basic substrate is also suppressed, and it is considered that a profile with less tailing can be obtained even on the basic substrate.

【0024】

The aliphatic sulfonium salt represented by the formula (I) can be used as it is if there is a commercially available product, or can be produced according to a known method. For example, it can be produced according to the following reaction scheme by applying the method described in DN Kevill et al., J. Am. Chem. Soc., Vol.108, 1579-1585 (1986).

【0025】

<img file="JP2001192569A_D0004.tif" />【0026】

During the ceremony, Q¹ , Q² And m are as defined above, and X stands for halogens such as bromine and iodine.

【0027】

That is, the formula Q is applied to the sulfide compound corresponding to the above formula (A1).¹A halogenated hydrocarbon corresponding to -X is allowed to act, or a sulfide compound corresponding to the above formula (A2) is subjected to the formula Q.²A halogenated hydrocarbon corresponding to -X is allowed to act to produce a sulfonium halide corresponding to the above formula (B), and further formula C_mF_{2m + 1}SO₃By allowing silver perfluoroalkanesulfonate corresponding to Ag to act, an aliphatic sulfonium salt represented by the formula (I) can be obtained. These reactions are carried out in a suitable solvent, for example, in a solvent such as acetonitrile, nitromethane, ethyl acetate and the like. Expression Q¹-X or formula Q²The halogenated hydrocarbon corresponding to -X is preferably used in excess of the sulfide compound of the formula (A1) or the formula (A2), for example, about 3 to 20 mol times, and the formula C._mF_{2m + 1}SO₃The silver perfluoroalkanesulfonate corresponding to Ag may be used in an amount approximately equal to that of the sulfide compound of the formula (A1) or the formula (A2) used for the formation of the sulfonium halide of the formula (B). After completion of the reaction, the produced silver halide is removed by filtration or the like, and then post-treatment such as concentration or recrystallization is performed to obtain an aliphatic sulfonium salt of the formula (I). Of course, the compound represented by the formula (Ia) can be produced in the same manner by replacing m in the above reaction scheme with n.

【0028】

Specific examples of the aliphatic sulfonium salt represented by the formula (I) include the following compounds, and among these exemplified compounds, those labeled with (Ia) at the end are described in the above formula (Ia). It is also a compound with a large number of carbon atoms in the sulfonate anion moiety corresponding to Ia).

【0029】

Cyclohexylmethyl (2-oxocyclohexyl) Sulfonium Trifluoromethanesulfonate (in formula (I), Q¹ = Methyl, Q² = Cyclohexyl, compound of m = 1), 1-adamantylmethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate (in formula (I), Q¹ = Methyl, Q² = 1-adamantyl, compound of m = 1), methyl (2-norbornyl) (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate (in formula (I), Q¹ = Methyl, Q² = 2-norbornyl, compound of m = 1), dimethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate (in formula (I), Q¹ = Q² = Methyl, compound of m = 1), methyl (2-oxocyclohexyl) propylsulfonium trifluoromethanesulfonate (in formula (I), Q¹ = Propyl, Q² = Methyl, compound of m = 1), [0030]

Cyclohexylmethyl (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate (in formula (I), Q¹ = Methyl, Q² = Cyclohexyl, compound of m = 4) (Ia), 1-adamantylmethyl (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate (in formula (I), Q¹ = Methyl, Q² = 1-adamantyl, compound of m = 4) (Ia), methyl (2-norbornyl) (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate (in formula (I), Q¹ = Methyl, Q² = 2-Norbornyl, compound of m = 4) (Ia), dimethyl (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate (in formula (I), Q¹ = Q² = Methyl, compound of m = 4) (Ia), methyl (2-oxocyclohexyl) propylsulfonium perfluorobutanesulfonate (in formula (I), Q¹ = Propyl, Q² = Methyl, compound of m = 4) (Ia), [0031]

Cyclohexylmethyl (2-oxocyclohexyl) Sulfonium Perfluorooctane Sulfonium (in formula (I), Q¹= Methyl, Q²= Cyclohexyl, compound of m = 8) (Ia), 1-adamantylmethyl (2-oxocyclohexyl) sulfonium perfluorooctane sulfonate (in formula (I), Q¹ = Methyl, Q² = 1-adamantyl, compound of m = 8) (Ia), methyl (2-norbornyl) (2-oxocyclohexyl) sulfonium perfluorooctane sulfonate (in formula (I), Q¹ = Methyl, Q² = 2-Norbornyl, compound of m = 8) (Ia), dimethyl (2-oxocyclohexyl) sulfonium perfluorooctane sulfonate (in formula (I), Q¹ = Q² = Methyl, compound of m = 8) (Ia), methyl (2-oxocyclohexyl) propylsulfonium perfluorooctanesulfonate (in formula (I), Q¹ = Propyl, Q² = Methyl, compound of m = 8) (Ia), etc.

【0032】

Next, the formulas (IIa) and (IIb) representing at least one onium salt selected from the triphenylsulfonium salt and the diphenyliodonium salt, which are essential components in the composition specified from the first viewpoint in the present invention. In Q³, Q⁴, Q⁵, Q⁶And Q⁷Are hydrogen, hydroxyl group, alkyl having 1 to 6 carbon atoms or alkoxy having 1 to 6 carbon atoms, respectively, and alkyl and alkoxy may be linear or branched when they have 3 or more carbon atoms. Specific examples of alkyl include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl and the like, and examples of alkoxy include methoxy, ethoxy, propoxy, butoxy and the like. Further, in the formulas (IIa) and (IIb), p and q representing the carbon number of the alkane moiety constituting the perfluoroalkane sulfonate anion are integers of 4 to 8. Similar to the aliphatic sulfonium salt represented by the above formula (Ia), the triphenylsulfonium salt having such a perfluoroalkanesulfonate anion having a large number of carbon atoms has improved resolution, and is further a basic substrate or a low reflectance substrate. It is advantageous for improving the profile above.

【0033】

The triphenylsulfonium salt represented by the formula (IIa) and the diphenyliodonium salt represented by the formula (IIb) can be used as they are if they are commercially available, or can be produced according to a conventional method. is there. Examples of the method for producing the triphenylsulfonium salt (IIa) include a method of reacting the corresponding triphenylsulfonium bromide with silver perfluoroalkanesulfonate, and the description of Chem. Pharm. Bull., Vol.29, 3753 (1981). A method for reacting a corresponding diphenyl sulfoxide, a benzene compound, and a perfluoroalkane sulfonic acid in the presence of trifluoroacetate anhydride, according to JP-A-8-311018. It can be produced by reacting a greenia reagent with thionyl chloride, then reacting with triorganosilyl halide to obtain triarylsulfonium halide, and then reacting with silver perfluoroalkanesulfonate. Also, Q in equation (IIa)³ , Q⁴ And / or Q⁵ For a compound in which is a hydroxyl group, a triphenylsulfonium salt having a tert-butoxy group on the benzene ring is treated with the same sulfonic acid as the anion of the compound in accordance with the description in JP-A-8-311018. It can be produced by removing the tert-butyl group.

【0034】

Further, as a method for producing the diphenyliodonium salt (IIb), for example, according to the description of J. Am. Chem. Soc., Vol.81, 342 (1959), after reacting iodil sulfuric acid with an aryl compound corresponding to it. , Perfluoroalkane sulfonic acid is added, concentrated sulfuric acid is added dropwise to a mixture of the corresponding aryl compound, acetic anhydride and potassium iodate, and then perfluoroalcan sulfonic acid is added, or acetic anhydride. It can be produced by a method of adding perfluoroalkanesulfonic acid after reacting an aryl compound corresponding to a reaction product obtained by adding iodine and trifluoroacetic acid to a mixed solution of fuming sulfuric acid.

【0035】

Specific examples of the triphenylsulfonium salt and the diphenyliodonium salt corresponding to the formulas (IIa) and (IIb) include the following compounds.

【0036】

Triphenylsulfonium Perfluorobutane Sulfonium, 4-Methylphenyldiphenylsulfonium Perfluorobutane Sulfonium, 4-Hydroxyphenyldiphenylsulfonium Perfluorobutane Sulfonium, 4-methoxyphenyldiphenylsulfonium Perfluorobutane Sulfonium, Tris (4-Methylphenyl) Sulfonium Per Fluorobutane Sulfonium, Tris (4-methoxyphenyl) Sulfonium Perfluorobutane Sulfonium, Triphenylsulfonium Perfluorooctane Sulfonium, 4-Methylphenyldiphenylsulfonium Perfluorooctane Sulfonium, 4-Hydroxyphenyldiphenylsulfonium Perfluorooctane Sulfonium, 4-methoxy Phenyldiphenylsulfonium Perfluorooctane Sulfonium, Tris (4-Methylphenyl) Sulfonium Perfluorooctane Sulfonium Tris (4-Methoxyphenyl) Sulfonium Perfluorooctane Sulfonium Diphenyliodonium Perfluorobutane sulfonate, di (4-methoxyphenyl) iodonium perfluorooctane sulfonate Di (4-tert-butylphenyl) iodonium perfluorooctane sulfonate, etc.

【0037】

Next, the resin components constituting the resist composition of the present invention will be described. This resin has a polymerization unit having an acid-unstable group. Resins for chemically amplified positive resists are generally insoluble or sparingly soluble in alkalis by themselves, but some groups are cleaved by the action of an acid, and after the cleaves, they become alkali-soluble. The acid-labile groups in the present invention can also be of various conventionally known groups. Specific examples of acid-labile groups include various esters of carboxylic acids, such as alkyl esters represented by methyl esters and tert-butyl esters, methoxymethyl esters, ethoxymethyl esters, 1-ethoxyethyl esters, and 1-. Isobutoxyethyl ester, 1-isopropoxyethyl ester, 1-ethoxypropyl ester, 1- (2-methoxyethoxy) ethyl ester, 1- (2-acetoxyethoxy) ethyl ester, 1-[2- (1-adamantyloxy) ) Ethoxy] ethyl ester, 1- [2- (1-adamantan carbonyloxy) ethoxy] ethyl ester, acetal type esters such as tetrahydro-2-furyl ester and tetrahydro-2-pyranyl ester, isobornyl ester and 2- Examples include alicyclic esters such as alkyl-2-adamantyl esters. The monomer leading to the polymerization unit having such a carboxylic acid ester may be a (meth) acrylic type such as a methacrylic acid ester or an acrylic acid ester, or a norbornene carboxylic acid ester, a tricyclodecene carboxylic acid ester, or a tetracyclo. A carboxylic acid ester group may be bonded to an alicyclic monomer, such as a decene carboxylic acid ester.

【0038】

Among such polymerization units having an acid-unstable group, a resin having a polymerization unit of 2-alkyl-2-adamantyl (meth) acrylate is preferable in terms of the resolution of the resist containing the polymerization unit. This polymerization unit is formed by opening the double bond of the (meth) acrylic acid moiety in 2-alkyl-2-adamantyl acrylate or 2-alkyl-2-adamantyl methacrylate. It can be expressed by equation (III).

【0039】

<img file="JP2001192569A_D0005.tif" />【0040】

In the formula, R¹ Represents hydrogen or methyl, R² Represents alkyl.

【0041】

The polymerization unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (III) secures the transmittance of the resist and improves the dry etching resistance due to the presence of the adamantane ring which is an alicyclic ring. Contribute to. Furthermore, 2-alkyl-2-adamantyl in this unit is cleaved by the action of an acid, so this unit contributes to increasing the alkali solubility of the resist membrane after exposure. R in equation (III)² Is an alkyl, and this alkyl can have, for example, about 1 to 8 carbon atoms, and is usually advantageous to be linear, but when it has 3 or more carbon atoms, it may be branched. Specific R² Examples include methyl, ethyl, propyl, isopropyl, butyl and the like. Above all, R² Is methyl or ethyl, which is advantageous for improving the adhesiveness between the resist and the substrate and improving the resolution.

【0042】

Specific examples of the monomer for leading to the polymerization unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (III) include 2-methyl-2-adamantyl acrylate and 2-ethyl acrylate. -2-adamantyl, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate and the like can be mentioned. 2-Alkyl-2-adamantyl (meth) acrylate can usually be produced by the reaction of 2-alkyl-2-adamantanol or a metal salt thereof with an acrylate or a methacrylic acid halide.

【0043】

Of course, the resin specified in the present invention may contain other polymerization units that do not cleave or are difficult to cleave due to the action of the acid, in addition to the above-mentioned polymerization units having an acid-unstable group. It is possible. Other polymerization units that can be contained include, for example, polymerization units of monomers having a free carboxylic acid group such as acrylic acid and methacrylic acid, and aliphatic unsaturated dicarboxylic acid anhydrides such as maleic anhydride and itaconic anhydride. Polymerization unit of, 2-norbornene polymerization unit, (meth) acrylonitrile polymerization unit, (meth) acrylate 2-hydroxyethyl, (meth) acrylate 3-hydroxy-1-adamantyl, (meth) acryloyloxy-γ-butyrolactone Examples of polymerization units of various (meth) acrylic acid esters such as.

【0044】

In particular, the polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate or the polymerization unit of (meth) acryloyloxy-γ-butyrolactone in which the lactone ring may be substituted with alkyl is the adhesiveness of the resist to the substrate. It is preferably used in terms of points. The polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate referred to here is formed by opening the double bond of the (meth) acrylate portion in the corresponding 3-hydroxy-1-adamantyl (meth) acrylate. The polymerization unit of (meth) acrylicyloxy-γ-butyrolactone, in which the lactone ring may be substituted with alkyl, is α- (meth) acrylicyloxy-, which is unsubstituted or substituted with alkyl on the lactone ring. The unit formed by opening the double bond of the (meth) acrylic acid moiety in γ-butyrolactone or the lactone ring may be substituted with alkyl β-unsubstituted or β- (meth) in which the lactone ring is substituted with alkyl. It means a unit formed by opening the double bond of the (meth) acrylic acid moiety in acryloyloxy-γ-butyrolactone, and can be represented by the following formulas (IV), (V) and (VI), respectively.

【0045】

<img file="JP2001192569A_D0006.tif" />【0046】

In the formula, R³ And R⁴ Represents hydrogen or methyl independently of each other, R⁵ , R⁶ And R⁷ Represents hydrogen or alkyl independently of each other⁸Represents hydrogen or hydroxyl group.

【0047】

3-Hydroxy-1-adamantyls (meth) acrylates for deriving the units of formula (IV) are commercially available, for example by reacting the corresponding hydroxyadamantanes with (meth) acrylates or halides thereof. It can also be manufactured. Further, in the α- or β- (meth) acrylicyloxy-γ-butyrolactone for leading to the unit of the formula (V) or the formula (VI), the lactone ring may be substituted with an alkyl α- or β-bromo-. By reacting γ-butyrolactone with acrylic acid or methacrylic acid, or by reacting α- or β-hydroxy-γ-butyrolactone with an acrylic acid halide or methacrylic acid halide whose lactone ring may be substituted with alkyl. Can be manufactured.

【0048】

The polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate represented by the formula (IV), the polymerization unit of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula (V), and the polymerization unit of the formula (VI). The polymerization units of β- (meth) acrylicyloxy-γ-butyrolactone are all highly polar, and the presence of any of them in the resin improves the adhesiveness of the resist containing them to the substrate. These polymerization units also contribute to improving the resolution of the resist. Furthermore, the polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate also contributes to the improvement of the dry etching resistance of the resist. In addition, the polymerization unit of β- (meth) acryloyloxy-γ-butyrolactone also contributes to the improvement of the transmittance of the resist.

【0049】

The monomers for leading to the polymerization unit of 3-hydroxy-1-adamantyl (meth) acrylate represented by the formula (IV) are 3-hydroxy-1-adamantyl acrylate, 3-hydroxy-1-adamantyl methacrylate, and acrylic. Examples thereof include 3,5-dihydroxy-1-adamantyl acid and 3,5-dihydroxy-1-adamantyl methacrylate. Also, in equations (V) and equations (VI), R⁵ , R⁶ And R⁷Are hydrogen or alkyl, respectively, and this alkyl can have about 1 to 6 carbon atoms, and when it has 3 or more carbon atoms, it may be linear or branched. R⁵ , R⁶ And R⁷ Specific examples of the alkyl represented by are methyl, ethyl, propyl, butyl and the like. Examples of the monomer for leading to the polymerization unit of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula (V) include α-acryloyloxy-γ-butyrolactone, α-methacryloyloxy-γ-butyrolactone, and α-. Acryloyloxy-β, β-dimethyl-γ-butyrolactone, α-methacryloyloxy-β, β-dimethyl-γ-butyrolactone, α-acryloyloxy-α-methyl-γ-butyrolactone, α-methacryloyloxy-α-methyl- γ-Butyrolactone and the like can be mentioned. Examples of the monomer for leading to the polymerization unit of β- (meth) acryloyloxy-γ-butyrolactone represented by the formula (VI) include β-acryloyloxy-γ-butyrolactone and β-methacryloyloxy-γ-butyrolactone. Examples thereof include β-methacryloyloxy-α-methyl-γ-butyrolactone.

【0050】

In addition, the resin containing the polymerization unit of 2-norbornene has a tough structure because it has an alicyclic group directly in its main chain, and exhibits excellent dry etching resistance. The polymerization unit of 2-norbornene can be introduced into the main chain by radical polymerization using, for example, in addition to the corresponding 2-norbornene, an aliphatic unsaturated dicarboxylic acid anhydride such as maleic anhydride or itaconic anhydride. Therefore, the polymerization unit of 2-norbornene is formed by opening its double bond and can be represented by the formula (VII). Further, the polymerization unit of maleic anhydride and the polymerization unit of itaconic anhydride, which are the polymerization units of the aliphatic unsaturated dicarboxylic acid anhydride, are formed by opening their double bonds, respectively. It can be represented by (IX).

【0051】

<img file="JP2001192569A_D0007.tif" />【0052】

Here, R in equation (VII)⁹And R¹⁰Represents hydrogen, alkyl with 1-3 carbon atoms, hydroxyalkyl with 1-3 carbon atoms, carboxyl, cyano or group-COOZ (Z is an alcohol residue), or R independently of each other.⁹And R¹⁰Can also be combined to form the carboxylic acid anhydride residue represented by -C (= O) OC (= O)-. R⁹And / or R¹⁰Specific examples of the case where is alkyl include methyl, ethyl, propyl and the like, and specific examples of the case where is hydroxyalkyl include hydroxymethyl, 2-hydroxyethyl and the like. R⁹And / or R¹⁰When is a group-COOZ, the carboxyl is an ester, and the alcohol residue corresponding to Z is, for example, an alkyl having about 1 to 8 carbon atoms which may be substituted, 2-oxooxo. Examples thereof include orchid-3- or -4-yl, and examples of the alkyl substituent include a hydroxyl group and an alicyclic hydrocarbon residue. So R⁹And / or R¹⁰Specific examples of the case where is a carboxylic acid ester residue represented by -COOZ include methoxycarbonyl, ethoxycarbonyl, 2-hydroxyethoxycarbonyl, tert-butoxycarbonyl, 2-oxooxolan-3-yloxycarbonyl, 2 -Oxooxolan-4-yloxycarbonyl, 1,1,2-trimethylpropoxycarbonyl, 1-cyclohexyl-1-methylethoxycarbonyl, 1- (4-methylcyclohexyl) -1-methylethoxycarbonyl, 1- (1) -Adamantyl) -1-methylethoxycarbonyl and the like.

【0053】

Specific examples of the monomer for leading to the polymerization unit of 2-norbornene represented by the formula (VI) include the following compounds.

【0054】

2-Norbornene 2-Hydroxy-5-norbornene 5-Norbornene-2-carboxylic acid Methyl 5-norbornene-2-carboxylate 5-Norbornene-2-carboxylic acid-t-butyl 5-Norbornene-2-carboxylic acid 1-cyclohexyl-1-methylethyl, 5-norbornene-2-carboxylic acid 1- (4-methylcyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1-( 4-Hydroxycyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1-methyl-1- (4-oxocyclohexyl) ethyl, 5-norbornene-2-carboxylic acid 1- (1-adamantyl) -1 -Methylethyl, 5-norbornene-2-carboxylic acid 1-methylcyclohexyl, 5-norbornene-2-carboxylic acid 2-methyl-2-adamantyl, 5-norbornene-2-carboxylic acid 2-ethyl-2-adamantyl 5- 2-Hydroxy-1-ethyl norbornene-2-carboxylic acid, 5-norbornene-2-methanol, 5-norbornene-2,3-dicarboxylic acid anhydride, etc.

【0055】

The resin used in the present invention varies depending on the type of radiation for patterning exposure and the type of acid-unstable group, but generally, the polymerization unit having an acid-unstable group is 10 to 80 mol%. It is preferably contained in a range. And especially as an acid-labile group, formula (III) When the polymerization unit of 2-alkyl-2-adamantyl (meth) acrylate represented by is used, it is advantageous that this unit accounts for 15 mol% or more of the total resin. In addition to the polymerization unit having an acid-unstable group, other polymerization units that are not easily cleaved by the action of the acid, for example, 3-hydroxy-1-adamantyl (meth) acrylate represented by the formula (IV). Polymerization unit of α- (meth) acryloyloxy-γ-butyrolactone represented by the formula (V), polymerization unit of β- (meth) acryloyloxy-γ-butyrolactone represented by the formula (VI), formula (VII) 2-Norbornene polymerization unit represented by, aliphatic unsaturated dicarboxylic acid anhydride polymerization unit, maleic anhydride polymerization unit represented by formula (VIII), itaconic anhydride polymerization unit represented by formula (IX) When such substances are present, it is preferable that the total of them is in the range of 20 to 90 mol% of the total resin.

【0056】

Therefore, the (meth) acrylic acid 3 represented by the formula (IV) together with the polymerization unit having an acid-unstable group containing the unit of 2-alkyl-2-adamantyl (meth) acrylate represented by the formula (III). -Polymerization unit of hydroxy-1-adamantyl and / or polymerization unit of α- (meth) acryloyloxy-γ-butyrolactone represented by formula (V), and polymerization unit of 2-norbornene represented by formula (VII) and formula ( In the case of a copolymer having a polymerization unit of an aliphatic unsaturated dicarboxylic acid anhydride represented by VIII) and (IX), 10 to 80 mol% of a monomer having an acid-unstable group is used, particularly the formula (III). ) 2-alkyl-2-adamantyl (meth) acrylate to lead to the unit of formula (IV) in an amount of 15 mol% or more, and 3-hydroxy-1-adamantyl (meth) acrylate to lead to the unit of formula (IV) and / or The alkyl may be substituted on the lactone ring to lead to the unit of formula (V) α- (meth) acryloyloxy-γ-butyrolactone and 2-norbornenes and aliphatic non-polymer to lead to the unit of formula (VII). It is common to copolymerize a monomer mixture containing a total of 20-90 mol% of the monomers leading to the polymerization unit of the saturated dicarboxylic acid anhydride. When 2-norbornenes and aliphatic unsaturated dicarboxylic acid anhydrides are used as copolymerization monomers, they tend to be difficult to polymerize. Therefore, in consideration of this point, it is preferable to use them in excess. .. Similarly, in the case of a copolymer having a polymerization unit of β- (meth) acryloyloxy-γ-butyrolactone represented by the formula (VI) together with a polymerization unit having an acid-labile group, an acid-labile group is similarly used. Monomer mixture containing 10 to 80 mol% of the monomer having, and 20 to 90 mol% of β- (meth) acryloyloxy-γ-butyrolactone in which the lactone ring for leading to the unit of formula (VI) may be substituted with alkyl. It is advantageous to copolymerize.

【0057】

Further, in general, in a chemically amplified positive resist composition, by adding a basic compound, particularly a basic nitrogen-containing organic compound, for example, amines as a questionnaire, the acid is deactivated due to the retention after exposure. It is known that the performance deterioration due to the above can be improved, and it is preferable to blend such a basic compound also in the present invention. Specific examples of the basic compounds used in the quencher include those represented by the following formulas.

【0058】

<img file="JP2001192569A_D0008.tif" />【0059】

In the formula, R¹¹, R¹², R¹³, R¹⁴And R¹⁵Represents alkyl, cycloalkyl, aryl or alkoxy which may be substituted with hydrogen or hydroxyl group independently of each other, and A represents alkylene, carbonyl or imino. Where R¹¹~ R¹⁵Alkoxy and alkoxy represented by can have about 1 to 6 carbon atoms, cycloalkyl can have about 5 to 10 carbon atoms, and aryl can have about 6 to 10 carbon atoms. Can be done. Further, the alkylene represented by A can have about 1 to 6 carbon atoms, and may be linear or branched. Among such basic compounds, the 2,6-dialkylpyridine compound represented by the following formula (X) is effective in improving the stability of the resist over time.

【0060】

<img file="JP2001192569A_D0009.tif" />【0061】

In the formula, R²¹And R²²Represents alkyl having 1 to 4 carbon atoms independently of each other. Specific examples of the 2,6-dialkylpyridine compound include 2,6-lutidine, 2-ethyl-6-methylpyridine, 2,6-di-tert-butylpyridine and the like. This 2,6-dialkylpyridine compound can be used alone as a quencher, or can be used in combination with other basic compounds if desired.

【0062】

The resist composition of the present invention preferably contains a resin in the range of about 80 to 99.9% by weight and an acid generator in the range of about 0.1 to 20% by weight based on the total solid content. When the aliphatic sulfonium salt of the formula (I) and the triphenylsulfonium salt of the formula (II) are used in combination as an acid generator as in the composition specified from the first viewpoint in the present invention, both are usually 9 :. It is preferably used in a weight ratio of about 1 to 1: 9, and more preferably about 8: 2 to 2: 8. When a basic compound as a quencher is used, it is preferably contained in the range of about 0.01 to 1% by weight based on the total solid content of the resist composition. The composition can also contain small amounts of various additives such as sensitizers, solubilizers, other resins, surfactants, stabilizers, dyes, etc., if desired.

【0063】

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

【0064】

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

【0065】

[Example]

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In the examples,% and parts indicating the content or the amount used are based on weight unless otherwise specified. The weight average molecular weight is a value obtained by gel permeation chromatography using polystyrene as a standard product.

【0066】

Monomer synthesis example 1: Synthesis of 2-methyl-2-adamantyl methacrylate 83.1 parts of 2-methyl-2-adamantanol and 101 parts of triethylamine were charged, and 200 parts of methyl isobutyl ketone was added to prepare a solution. 78.4 parts of methacrylic acid chloride (1.5 mol times as much as 2-methyl-2-adamantanol) was added dropwise thereto, and then the mixture was stirred at room temperature for about 10 hours. After filtration, the organic layer was washed with a 5% aqueous sodium bicarbonate solution, followed by two washings with water. The organic layer was concentrated and then distilled under reduced pressure to obtain 2-methyl-2-adamantyl methacrylate represented by the following formula.

【0067】

<img file="JP2001192569A_D0010.tif" />【0068】

Monomer synthesis example 2: Synthesis of 2-ethyl-2-adamantyl methacrylate 2-Add 50 parts of diethyl ether to 31.1 parts of adamantanone to make a solution, and while maintaining the temperature of this solution so that it does not exceed 10 ° C, 200 ml of diethyl ether solution containing ethyl lithium at a concentration of 1.14 mol / L. Was dropped. After stirring at 0 ° C for 2 hours as it was, 26.2 parts of methacrylic acid chloride (1.2 mol times as much as 2-adamantanone) was added dropwise while maintaining the temperature so as not to exceed 10 ° C. After completion of the dropping, the mixture was stirred at room temperature for 12 hours. Then, the precipitated inorganic salt was separated by filtration, and the organic layer was washed with a 5% aqueous sodium bicarbonate solution, followed by washing with water twice. The organic layer was concentrated and then distilled under reduced pressure to obtain 2-ethyl-2-adamantyl methacrylate represented by the following formula.

【0069】

<img file="JP2001192569A_D0011.tif" />【0070】

Monomer synthesis example 3: Synthesis of α-methacryloyloxy-γ-butyrolactone Add 100 parts of α-bromo-γ-butyrolactone and 104.4 parts of methacrylic acid (2.0 mol times as much as α-bromo-γ-butyrolactone), and add 3 times by weight of methyl isobutyl ketone as compared to α-bromo-γ-butyrolactone. In addition, it was prepared as a solution. 183.6 parts of triethylamine (3.0 mol times as much as α-bromo-γ-butyrolactone) was added dropwise thereto, and then the mixture was stirred at room temperature for about 10 hours. After filtration, the organic layer was washed with a 5% aqueous sodium bicarbonate solution, followed by two washings with water. The organic layer was concentrated to obtain α-methacryloyloxy-γ-butyrolactone represented by the following formula.

【0071】

<img file="JP2001192569A_D0012.tif" />【0072】

Resin synthesis example 1: Synthesis of resin A1 2-Methyl-2-adamantyl methacrylate and α-methacrylicoyloxy-γ-butyrolactone were charged at a molar ratio of 5: 5 (15.0 parts: 11.7 parts), and 2 times by weight of methyl isobutyl ketone was added to all the monomers. And made a solution. Azobisisobutyronitrile was added thereto as an initiator in an amount of 2 mol% based on the total amount of the monomers, and the mixture was heated at 80 ° C. for about 8 hours. Then, the reaction solution was poured into a large amount of heptane and precipitated by performing the operation three times for purification. As a result, a copolymer having a weight average molecular weight of about 10,000 was obtained. This copolymer has each polymerization unit of the following formula, and this is referred to as resin A1.

【0073】

<img file="JP2001192569A_D0013.tif" />【0074】

Resin synthesis example 2: Synthesis of resin A2 2-Ethyl-2-adamantyl methacrylate, 3-hydroxy-1-adamantyl methacrylate, and α-methacryloyloxy-γ-butyrolactone in a molar ratio of 5: 2.5: 2.5 (20.0 parts: 9.5 parts: 7.3 parts) The operation was carried out in the same manner as in Resin Synthesis Example 1 except that the preparation was carried out in. As a result, a copolymer having a weight average molecular weight of about 9,200 was obtained. This copolymer has each unit represented by the following formula, and this is referred to as resin A2.

【0075】

<img file="JP2001192569A_D0014.tif" />【0076】

Resin synthesis example 3: Synthesis of resin A3 2-Adamantyl-2-ethyl methacrylate, 1-adamantyl-3-hydroxyacrylic acid, norbornene and maleic anhydride in a molar ratio of 2: 2: 3: 3 (10.0 parts: 9.0 parts: 5.7 parts: 5.9 parts). After charging and adding methyl isobutyl ketone, which is 2 times by weight of all the monomers, the temperature was raised to 80 ° C in a nitrogen atmosphere. Azobisisobutyronitrile was added thereto as an initiator in an amount of 3 mol% based on the total amount of the monomers, and the mixture was heated at 80 ° C. for about 15 hours. Then, the reaction solution was poured into a large amount of methanol and precipitated three times to obtain a copolymer (17.1 parts) having a weight average molecular weight of about 12160 and a dispersion of 1.90. This copolymer has each unit represented by the following formula, and this is referred to as resin A3.

【0077】

<img file="JP2001192569A_D0015.tif" />【0078】

Acid Generator Synthesis Example 1: Synthesis of cyclohexylmethyl (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate 3.2 parts of 2- (cyclohexylthio) cyclohexanone and 10.0 parts of nitromethane were placed in a four-necked flask and cooled to 15 ° C. 19.2 parts of methyl iodide was charged therein, and the mixture was stirred at the same temperature for 2 hours. Then, 6.10 parts of silver perfluorobutanesulfonate dissolved in 200 parts of nitromethane was gradually added dropwise. After stirring at the same temperature for 6 hours, the precipitated silver iodide was filtered off, and the silver iodide was washed with 32 parts of nitromethane. The filtrate and washings were combined and concentrated to 8.4 parts and added to 260 parts of diethyl ether. The precipitated crystals were filtered and washed with 30 parts of diethyl ether to obtain 1.35 parts of the desired product. Yield 17.1%. The compound is cyclohexylmethyl (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate represented by the following formula.¹Confirmed by 1 H-NMR (GX-270 manufactured by JEOL Ltd.).

【0079】

<img file="JP2001192569A_D0016.tif" />【0080】

Melting point 86 ~ 88 ° C¹H-NMR (CDCl₃, Internal standard substance tetramethylsilane): δ (ppm) 1.15-2.32 (m, 15H); 2.52-2.83 (m, 3H); 2.83 (s, 1.5H); 2.96 (s, 1.5H); 3.57 (tt , 0.5H); 3.85 (tt, 0.5H); 5.36 (dd, 0.5H); 5.50 (dd, 0.5H). [0081]

Acid Generator Synthesis Example 2: Synthesis of Cyclohexylmethyl (2-oxocyclohexyl) Sulfonium Perfluorooctane Sulfonium A four-necked flask was charged with 4.25 parts of 2- (cyclohexylthio) cyclohexanone and 13.0 parts of nitromethane, and cooled to 15 ° C. 25.5 parts of methyl iodide was charged therein, and the mixture was stirred at the same temperature for 2 hours. Then, 12.14 parts of silver perfluorooctanesulfonate dissolved in 750 parts of nitromethane was gradually added dropwise. After stirring at the same temperature for 18 hours, the precipitated silver iodide was filtered off, and the silver iodide was washed with 40 parts of nitromethane. The filtrate and washings were combined and concentrated to 15.1 parts and added to 600 parts of diethyl ether. The precipitated crystals were filtered and washed with 50 parts of diethyl ether to obtain 6.22 parts of the desired product. Yield 42.8%. The compound is cyclohexylmethyl (2-oxocyclohexyl) sulfonium perfluorooctane sulfonate represented by the following formula.¹Confirmed by 1 H-NMR.

【0082】

<img file="JP2001192569A_D0017.tif" />【0083】

¹H-NMR (CDCl₃, Internal standard substance tetramethylsilane): δ (ppm) 1.15-2.32 (m, 15H); 2.52-2.83 (m, 3H); 2.83 (s, 1.5H); 2.95 (s, 1.5H); 3.58 (tt , 0.5H); 3.86 (tt, 0.5H); 5.38 (dd, 0.5H); 5.51 (dd, 0.5H). [0084]

Acid Generator Synthesis Example 3: Synthesis of 4-Methylphenyldiphenylsulfonium Perfluorooctanesulfonate 8.0 parts of diphenyl sulfoxide and 80.0 parts of toluene were placed in a four-necked flask and cooled to 2 ° C. Next, 16.6 parts of trifluoroacetic anhydride and 19.8 parts of perfluorooctanesulfonic acid were charged, and the mixture was stirred at the same temperature for 30 minutes. After standing, the lower layer was concentrated and diluted with 340 parts of chloroform. The obtained chloroform solution was washed 6 times with 85 parts of ion-exchanged water and then concentrated to obtain 27.7 parts of 4-methylphenyldiphenylsulfonium perfluorooctanesulfonate.

【0085】

Next, an example in which a resist composition was prepared and evaluated using the following acid generators B1 to B3, C1 and C2 is shown.

【0086】

Acid Generator B1: Cyclohexylmethyl (2-oxocyclohexyl) Sulfonium Perfluoromethanesulfonate (CMS-105 manufactured by Midori Kagaku Co., Ltd.) Acid generator B2: Cyclohexylmethyl (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate (product according to acid generator synthesis example 1) Acid Generator B3: Cyclohexylmethyl (2-oxocyclohexyl) Sulfonium Perfluorooctane Sulfonium (Product by Acid Generator Synthesis Example 2) Acid Generator C1: 4-Methylphenyldiphenylsulfonium Perfluorooctane Sulfonium (Product by Acid Generator Synthesis Example 3) Acid generator C2: 4-Methylphenyldiphenylsulfonium perfluoromethanesulfonate (MDS-205 manufactured by Midori Chemical Co., Ltd.) [0087]

Example 1 Each component shown below was mixed and further filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist solution.

【0088】

<img file="JP2001192569A_D0018.tif" />【0089】

After drying the above resist solution on a silicon wafer coated with Brewer's "DUV-30" and baked at 215 ° C for 60 seconds to form an organic antireflection film with a thickness of 1,600 Å. Spin coating was performed so that the film thickness was 0.39 μm. After applying the resist solution, it was prebaked on a direct hot plate at 100 ° C. for 60 seconds. On the wafer on which the resist film was formed in this way, an ArF excimer exposure machine [NSR ArF manufactured by Nikon Corporation, NA = 0.55, σ = 0.6] was used to gradually change the exposure amount to create a line-and-space pattern. Exposed. After the exposure, post-exposure baking was performed on a hot plate at 115 ° C. for 60 seconds, and paddle development was further performed with a 2.38% tetramethylammonium hydroxide aqueous solution for 60 seconds. The developed pattern was observed with a scanning electron microscope, and the effective sensitivity and resolution were examined by the following methods. The effective sensitivity was 22 mJ / cm.² The resolution was 0.16 μm.

【0090】

Effective sensitivity: The line-and-space pattern of 0.18 μm was displayed at the minimum exposure amount of 1: 1.

【0091】

Resolution: Displayed with the minimum dimensions of the line-and-space pattern separated by the effective sensitivity exposure.

【0092】

Further, the above resist solution was applied onto a quartz glass wafer to form a resist film so that the film thickness after prebaking under the same conditions as above was 0.39 μm, and the resist film was formed at 193 nm. The transmittance was measured with a spectrophotometer. As a result, the transmittance was 62%. As described above, this resist exhibited high transmittance and also had good sensitivity and resolution.

【0093】

Examples 2 to 7 and Comparative Examples 1 to 2 The acid generator shown in Table 1 was mixed with each component shown below, and further filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist solution.

【0094】

<img file="JP2001192569A_D0019.tif" />【0095】

After drying the above resist solution on a silicon wafer coated with Brewer's "DUV-30" and baked at 215 ° C for 60 seconds to form an organic antireflection film with a thickness of 1,600 Å. Spin coating was performed so that the film thickness was 0.39 μm. After applying the resist solution, it was prebaked on a direct hot plate at 120 ° C. for 60 seconds. The wafer on which the resist film was formed was exposed to a line-and-space pattern in the same manner as in Example 1. After the exposure, post-exposure baking was performed on a hot plate at 120 ° C. for 60 seconds, and paddle development was further performed with a 2.38% tetramethylammonium hydroxide aqueous solution for 60 seconds. The developed pattern was observed with a scanning electron microscope, and the effective sensitivity and resolution were examined by the same method as in Example 1. In Example 7, "DUV-30J" was used instead of "DUV-30", and the baking temperature was 115 ° C. Further, the above resist solution was applied onto a quartz glass wafer to form a resist film so that the film thickness after prebaking under the same conditions as above was 0.39 μm, and the resist film was formed at 193 nm. The transmittance was measured. These results are summarized in Table 1.

【0096】

[table 1]

Example No. Resin Acid Generator Effective Sensitivity Resolution Transmittance Example 2 A2 B2 (1.0 part) 58 mJ / cm² 0.16 μm 72% 3 A2 B2 (0.2 copies) + C1 (0.25 copies) 42 mJ / cm² 0.15 μm 63% 4 A2 B3 (0.2 copies) + C1 (0.25 copies) 46 mJ / cm² 0.15 μm 58% 5 A2 B2 (0.4 copies) + C1 (0.2 copies) 42 mJ / cm² 0.15 μm 62% 6 A1 B2 (0.2 copies) + C1 (0.25 copies) 48 mJ / cm² 0.15 μm 60% 7 A3 B2 (0.2 copies) + C1 (0.25 copies) 47 mJ / cm² 0.16 μm 61% Comparative Example 1 A1 C2 (0.1 part) 70 mJ / cm² 0.17 μm 63% 2 A2 C2 (0.1 part) 62 mJ / cm² 0.17 μm 62% [0097]

As is clear from the results of Example 1 and the results of Table 1, the resist of Example is excellent in sensitivity and resolution when compared with the same transmittance. Further, the resist of Example 2 using cyclohexylmethyl (2-oxocyclohexyl) sulfonium perfluorobutane sulfonate alone as an acid generator has a high transmittance at 193 nm even if the amount of the acid generator is large. Since it is difficult to absorb the ArF excimer laser light used for exposure, it can be seen that it is effective in improving the profile.

【0098】

Example 8 A wafer (basic substrate) provided with a silicon nitride film having a thickness of 1,800 Å was surface-treated with hexamethyldisilazane by a conventional method, and then each resist solution prepared in Examples 3 and 5 was applied to this wafer, respectively. A resist film is formed by applying a resist film so that the film thickness after drying is 0.5 μm in the same manner as in the above example, and after patterning, the cross-sectional shape of the pattern is observed with a scanning electron microscope to determine the substrate dependence. evaluated. As a result, all of these patterns showed a good profile with no tailing.

【0099】

As described above, the resist of the example has improved resolution as compared with the resist of the comparative example using 4-methylphenyldiphenylsulfonium perfluoromethanesulfonate as an acid generator, and is good even when applied to a low reflectance substrate. Give a profile. Furthermore, the resists prepared in these examples are less likely to cause tailing profiles on basic substrates.

【0100】

Examples 9-11 Each component shown below was mixed and further filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist solution.

【0101】

Example 9 Example 10 Example 11 Resin A2 10 parts 10 parts A4 ^* 10 copies Acid generator B1 0.5 part 0.5 part 0.5 part C1 0.2 part 0.2 part 0.2 part Question: 2,6-Diisoprop aniline 0.015 copies 0.015 copies 0.015 copies 2,6-Ruchijin --0.01 copies- Solvent: Propyrene Recall Monomethyl Ether Acetate 57 parts 57 parts 57 parts γ-Buchirolactone 3 parts 3 parts 3 parts [0102]

^* Resin A4: A copolymer of 2-methyl-2-adamantyl methacrylate and β-methacrylicoyloxy-γ-butyrolactone having a molar ratio of 47.7 / 52.3, and having a weight average molecular weight of about 8,400.

【0103】

Of these, for the resist solutions of Example 9 and Example 10, they were divided into two, one was stored at 60 ° C for 24 hours and then returned to 23 ° C over 1 hour, and the other was 23 ° C during that time. Saved in. Then, the following tests were performed on each resist solution. The resist solution of Example 11 was subjected to the following test as it was.

【0104】

After drying the above resist solution on a silicon wafer coated with Brewer's "DUV-30" and baked at 215 ° C for 60 seconds to form an organic antireflection film with a thickness of 1,600 Å. Spin coating was performed so that the film thickness was 0.39 μm. After applying the resist solution, it was prebaked on a direct hot plate at 110 ° C. for 60 seconds. The wafer on which the resist film was formed was exposed to a line-and-space pattern in the same manner as in Example 1. After the exposure, post-exposure baking was performed on a hot plate at 115 ° C. for 60 seconds, and paddle development was further performed with a 2.38% tetramethylammonium hydroxide aqueous solution for 60 seconds. The developed pattern was observed with a scanning electron microscope, and the effective sensitivity and resolution were examined by the same method as in Example 1. Further, the above resist solution was applied onto a quartz glass wafer to form a resist film so that the film thickness after prebaking under the same conditions as above was 0.39 μm, and the resist film was formed at 193 nm. The transmittance was measured. These results are summarized in Table 2.

【0105】

[Table 2]

Examples Resin 2,6-Activity Sensitivity Resolution Transmittance Ruchiji 23 ° C storage 60 ° C storage 23 ° C storage 60 ° C storage 23 ° C 60 ° C Save Save 9 A2 --19 mJ / cm² 13 mJ / cm² 0.16 μm 0.16 μm 61% 58% 10 A2 Yes 20 mJ / cm² 18 mJ / cm² 0.16 μm 0.16 μm 61% 61% 11 A4 --13 mJ / cm² --0.16 μm --71% - [0106]

As is clear from these results, the resists of Examples 9 to 11 are good in sensitivity, resolution and transmittance. In particular, in Example 10 in which 2,6-lutidine was used as the quencher, the change in sensitivity and transmittance was small and the stability over time was improved even after the accelerated aging test for 24 hours at 60 ° C. Further, the resist of Example 11 using the resin A4 has a higher sensitivity and a high transmittance at 193 nm.

【0107】

[Effect of the invention]

According to the present invention, a resist composition using a specific acid generator has good resolution, and is used as a basic substrate or low in light with a wavelength of 220 nm or less, for example, exposure using ArF excimer laser light. Even when applied to a reflectance substrate, it gives a good profile and has the effect of being less dependent on the substrate.