Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-11-06
2004-01-06
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S326000, C430S914000, C430S905000, C430S919000, C430S921000, C430S327000, C430S328000, C430S330000, C430S331000
Reexamination Certificate
active
06673516
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a coating composition for a chemically amplified positive resist and to a method of patterning a resist using the coating composition.
(2) Description of the Related Art
Lithographic processes requiring the definition in the vicinity of 0.25 &mgr;m and using a chemically amplified positive resist have been launched in practical applications. Separately, with an increasing demand on semiconductor devices having less sizes, next-generation processes requiring fine patterns of from 0.13 &mgr;m to 0.22 &mgr;m using KrF excimer laser have been developed.
Under these circumstances, a demand has been made on improvement of the characteristics of resists such as sensitivity, definition and resist pattern sectional shapes (profiles). The present invention is aimed specifically to the definition and depth of focus.
Conventional positive resist compositions each containing 3-octanone as a resist solvent are described in Japanese Unexamined Patent Application Publications No. 5-34919, No. 4-29146, No. 62-251739 and No. 62-194249. These positive resist compositions are, however, positive resist compositions each containing a non-chemically-amplified naphthoquinonediazide photosensitizer and a cresol novolak resin. They are neither chemically amplified resist compositions nor compositions each containing a predetermined amount of an octanone as in the present invention and are still susceptible to improvement in definition and depth of focus. In such a chemically amplified resist, a resist is patterned by the reaction between an acid generated from an acid generator upon irradiation with light and a base resin having an acid-decomposable dissolution inhibiting group.
Japanese Unexamined Patent Application Publication No. 6-130665 proposes a chemically amplified resist using 2-octanone or 3-octanone as a resist solvent. However, the use of 2-octanone or 3-octanone as the solvent cannot yield desired definition and depth of focus.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a chemically amplified positive resist composition having improved definition and depth of focus.
The above-noted objects can be achieved by incorporating an (D)octanone into (B)a resin which exhibits increased solubility in an alkali aqueous solution by action of an acid, in a coating composition for a chemically amplified positive resist, in proportion of from 0.1 to 5 parts by weight of (D), relative to 100 parts by weight of (B).
Specifically, the present invention is a coating composition for a chemically amplified positive resist comprising (A) an acid generator which generates an acid upon irradiation with active light or radiant ray, (B) a resin ingredient which exhibits increased solubility in an alkali aqueous solution by action of an acid, (C) an organic solvent, and (D) an octanone, in a proportion of from 0.1 to 5 parts by weight relative to 100 parts by weight of the ingredient (B).
More specifically, the present invention is a coating composition for a chemically amplified positive resist produced by dissolving (A) an acid generator which generates an acid upon irradiation with active light or radiant ray and (B) a resin ingredient which exhibits increased solubility in an alkali aqueous solution by action of an acid, into (C) an organic solvent, characterized in the (D) octanone is formulated in a proportion of from 0.1 to 5 parts by weight relative to 100 parts by weight of the ingredient (B)
In another aspect, the present invention provides a method of patterning a resist, including the steps of applying a film of the aforementioned coating composition for a chemically amplified positive resist onto a substrate, prebaking the applied film at a temperature in the range of from 80° C. to 120° C., irradiating the prebaked film with active light or radiant ray through a patterned mask, subjecting the exposed film to post-exposure baking at a temperature in the range of from 80° C. to 130° C., and subjecting the resulting film to alkali-development.
DETAILED DESCRIPTION OF THE INVENTION
Ingredient (A)
Ingredients (A) for use in the present invention are not specifically limited and include any compounds that generate an acid upon irradiation with active light or radiant ray. The acid generator can appropriately be selected from conventional acid generators such as iodonium salts, sulfonium salts, and other onium salts; oxime sulfonates; bis(alkylsulfonyl)diazomethanes, bis(cycloalkylsulfonyl)diazomethanes, bis(arylsulfonyl)diazomethanes, nitrobenzylsulfonates, iminosulfonates, and disulfones. Among them, bis(alkylsulfonyl)diazomethanes, bis(cycloalkylsulfonyl)diazomethanes and bis(arylsulfonyl)diazomethanes are preferred.
Such diazomethanes include, for example, bis(n-propylsulfonyl)diazomethane, bis(isopropylsulfonyl)diazomethane, bis(n-butylsulfonyl)diazomethane, bis(isobutylsulfonyl)diazomethane, bis(tert-butylsulfonyl)diazomethane, and other bis(alkylsulfonyl)diazomethanes each having a straight- or branched-chain alkyl group; bis(cyclopentylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, and other bis(cycloalkylsulfonyl)diazomethanes each having a cyclic alkyl group; and bis(phenylsulfonyl)diazomethane, bis(p-methyphenylsulfonyl)diazomethane, bis (2,4-dimethylphenylsulfonyl)diazomethane, bis(p-methoxyphenylsulfonyl)diazomethane, and other bis(arylsulfonyl)diazomethanes each having a substituted or unsubstituted phenyl group.
The content of the ingredient (A) is preferably from 0.5 to 20 parts by weight and more preferably from 1 to 10 parts by weight, relative to 100 parts by weight of the ingredient (B).
Ingredient (B)
Ingredients (B) for use in the present invention are not specifically limited and include any resins which exhibit increased solubility in an alkaline aqueous solution by action of an acid. Such resins may be derived from known or conventional alkali-soluble resins, in which phenolic hydroxyl groups or hydroxyl groups of carboxyl groups of the resins are protected with an acid-decomposable dissolution inhibiting group, and the resulting resins become insoluble in an alkali. The dissolution inhibiting group in the resins is decomposed by action of an acid generated from the acid generator, and the resulting resins become soluble in an alkali.
As the ingredient (B), preferred are polymers each having a unit in which hydrogen atoms of hydroxy groups of hydroxystyrene are substituted with an “acetal” group serving as the acid-decomposable dissolution inhibiting group. Such acetal groups include, for example, ethoxyethyl group, methoxypropyl group and other lower alkoxyalkyl groups. Such polymers have excellent sensitivity, definition and good resist pattern profiles.
Specifically, preferred resins are resins derived from polyhydroxystyrenes, hydroxystyrene-styrene copolymers and copolymers of hydroxystyrene and (meth)acrylic acid or a (meth)acrylic ester, in which the hydroxystyrene unit is substituted with the acetal group.
To further improve definition and heat resistance, the resin ingredient preferably comprises both the acetal group and an acid-decomposable dissolution inhibiting group other than the acetal group. Such acid-decomposable dissolution inhibiting groups include, but are not limited to, tert-butoxycarbonyl group and other tertiary-alkyloxycarbonyl groups; tert-butoxycarbonylmethyl group and other tertiary-alkyloxycarbonyl-substituted alkyl groups; tert-butoxy group and other tertiary alkyl groups; and tetrahydropyranyl group, tetrahydrofuranyl group and other cyclic ether groups, and other conventional acid-decomposable dissolution inhibiting groups. In this case, the resin may be a resin blend as mentioned below or a copolymer containing a hydroxystyrene unit, a hydroxystyrene unit substituted with the acetal group, and a hydroxystyrene unit substituted with a dissolution inhibiting group other than the acetal group.
The ingredient (B) preferably comprises (b) a resin derived from a polymer having a weight average molecular weight of
Kumon Satoshi
Sato Kazufumi
Baxter Janet
Lee Sin J.
Sughrue & Mion, PLLC
Tokyo Ohka Kogyo Co. Ltd.
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