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
2001-11-27
2004-07-06
Chu, John S. (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
C430S905000
Reexamination Certificate
active
06759176
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a positive-working resist composition or, more particularly, to a chemical-amplification positive-working resist composition capable of forming a resist pattern having high transparency to active light of 200 nm wavelength or shorter or, in particular, to ArF excimer laser beams, high pattern resolution and excellent cross sectional profile, etching resistance of the resist pattern and adhesion to the substrate and further improved in the line edge roughness.
As the base resinous ingredient in a chemical-amplification resist, those used heretofore include polyhydroxystyrenes having high transparency to the KrF excimer laser beams (248 nm) and those by substitution of acid-dissociable solubility-reducing groups for the hydroxyl groups thereof.
However, semiconductor devices are now on the way toward higher and higher fineness and development works are actively undertaken for a process by using ArF excimer laser beams (193 nm).
In the process using ArF excimer laser beams (193 nm), resins having benzene nuclei such as polyhydroxystyrenes have a defect of insufficient transparency to these beams. In order to overcome this defect, many proposals are made heretofore for resins having the main-chain units derived from an acrylic acid ester or methacrylic acid ester having an adamantyl skeleton in the ester portion (referred to simply as an “acrylic acid ester resin” hereinafter) having no benzene nuclei and having excellent dry etching resistance (Japanese Patent No. 2881969, Patent Kokai No. 5-346668, Patent Kokai No. 7-234511, Patent Kokai No. 9-73173, Patent Kokai No. 9-90637, Patent Kokai No. 10-161313, Patent Kokai No. 10-319595, Patent Kokai No. 11-12326 and elsewhere).
A positive-working resist composition by using these acrylic acid ester resins is developable with a standard developer solution which is a 2.38% by mass aqueous solution of tetramethylammonium hydroxide and the results obtained are satisfactory to some extent in respects of the transparency to ArF excimer laser beams, dry etching resistance and adhesion to the substrate.
In the field of semiconductor devices nowadays, however, an ultrafine pattern further has become required necessitating pattern resolution at 150 nm or finer or in the vicinity of 100 nm while the above-mentioned effectiveness is no longer sufficient for such a requirement.
In order to obtain a resist pattern of such high pattern resolution in a good profile, it is necessary to decrease the resist film thickness (prior art film thickness: about 500 nm and now desired film thickness: 300-400 nm) and to increase the fraction of the acrylic ester units having acid-dissociable solubility-reducing groups (e.g., 2-methyladamantyl methacrylate units) in the base resin.
However, a decrease in the film thickness is accompanied by a relative increase in the film thickness reduction during dry etching as compared with that of a conventional film thickness so that it is necessary to further improve the dry etching resistance and an increase in the fraction of the acrylic ester units having acid-dissociable solubility-reducing groups is accompanied by an increase in the hydrophobicity resulting in a problem of degradation in the adhesion to the substrate. A difficulty is also encountered in the formation of a resist pattern with a good profile, as the size of a resist pattern is so fine.
Accordingly, along with the improvement in the pattern resolution, it has become required to obtain a good resist pattern profile together with improvements in the dry etching resistance and adhesion to the substrate. In order to satisfy these requirements, a proposal is made for a chemical-amplification resist composition containing a copolymer consisting of (meth)acrylic acid units having lactone ring-containing bridged saturated polycyclic hydrocarbon groups, (meth)acrylic acid units having bridged polycyclic hydrocarbon groups having acid-decomposable groups or carboxyl groups and (meth)acrylic acid or alkyl (meth)acrylate units and having a mass-average molecular weight of 2000 to 200000 (Japanese Patent Kokai No. 2000-26446).
Recently, an important problem came under attention, as for the ArF resists, besides the aforementioned requirements, for that, of which the target semiconductor design rule was still finer, to prevent drawbacks due to line edge roughness (LER) which is a phenomenon that non-uniform raggedness is formed along the outer peripheries of lines to decrease accuracy and fine surface roughening during etching but no solution has been obtained yet in this regard.
SUMMARY OF THE INVENTION
The present invention has been completed with an object to provide a chemical-amplification positive-working resist composition capable of giving a resist pattern of high pattern resolution having excellent dry etching resistance and adhesion to the substrate as well as a good profile with improved line edge roughness.
The inventors have continued extensive investigations on a chemical-amplification resist for ArF use and, as a result, have arrived at a discovery that great improvements can be accomplished in the dry etching resistance and adhesion to the substrate as well as line edge roughness by using, as the resinous ingredient capable of being imparted with increased solubility in alkali by the interaction with an acid to be used in combination with an acid-generating agent, a copolymer containing acrylic acid or methacrylic acid ester units having lactone ring-containing bridged saturated polycyclic hydrocarbon groups and acrylic acid or methacrylic acid ester units having straight-chain alkyl groups substituted by hydroxyl groups, alkoxy groups or acyl groups.
Namely, the present invention provides a chemical-amplification positive-working resist composition characterized by the use of, in a positive-working resist composition containing (A) a resinous ingredient capable of being imparted with increased solubility in alkali by interacting with an acid, (B) an acid-generating agent capable of generating an acid by irradiation with a radiation and (C) an organic solvent, as the component (A), a copolymer of which the monomer units constituting the main chain consist of (a1) acrylic acid ester or methacrylic acid ester units having solubility-reducing groups, (a2) the monomer units derived from an ester between acrylic acid or methacrylic acid and a lactone ring-containing bridged saturated polycyclic alcohol and (a3) the monomer units derived from an ester between acrylic acid or methacrylic acid and a straight-chain alcohol substituted by a hydroxyl group, alkoxy group or acyl group.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the composition of the present invention, the resinous ingredient (A) is necessarily a resin capable of being imparted with increased solubility in alkali by the interaction with an acid. Such a resin is exemplified, for example, by a polymer or copolymer having, in the main chain, the monomer units derived from an acrylic acid ester or methacrylic acid ester having a solubility-reducing group, of which the ester group is dissociated by an acid.
The polymer or copolymer here having the monomer units derived from an acrylic acid ester or methacrylic acid ester in the main chain is a polymer or copolymer having a main chain consisting of the monomer units represented by the general formula:
(R in the formula is a hydrogen atom or a methyl group).
It is essential that the same has a property that the solubility in alkali is increased by the acid generated when the acid-generating agent (B) used in combination receives interaction of a radiation and such a property is imparted by protecting the hydroxyl group of the carboxyl group of the monomer unit derived from acrylic acid or methacrylic acid with an acid-dissociable solubility-reducing group to give alkali-insolubility. As a result of conversion of the polymer or copolymer having such monomer units rendered alkali-soluble when the solubility-reducing groups are eliminated by the interaction of the acid generated from the
Fujimura Satoshi
Hada Hideo
Iwai Takeshi
Chu John S.
Tokyo Ohka Kogyo Co. Ltd.
Wenderoth Lind & Ponack LLP
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