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
2000-07-14
2002-03-19
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
C430S914000, C430S921000, C526S281000, C526S272000
Reexamination Certificate
active
06358666
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a chemically amplified resist composition which can be effectively used for micro-processing a semiconductor element using various types of radiation such as KrF or ArF excimer laser as far ultraviolet rays, X-ray as synchrotron radiation and electron beam as charged particle radiation and more particularly, to the chemically amplified resist composition comprising A) a polymer containing acid-decomposable functional groups for the manufacture of a resist, B) an acid generator, and C) a low molecular additive which can serve to enhance the dry etch resistance and resolution of patterns.
DESCRIPTION OF THE RELATED ART
In general, a semiconductor element is prepared through a lithographic process, wherein a resist is implanted on a silicon wafer to form a film; the film is radiated by a light to form a pattern, followed by development to form a positive or negative pattern.
In parallel with the recent trend that the semiconductor technology is being developed in a higher integration, higher density, smaller size and higher speed due to LSI and VLSI, there has been great demand for the micro-processing of the semiconductor element having ultramicro-patterns of less than 0.2 micron. To meet such market need, a wavelength in the exposed regions has been far shorter from the conventional g-ray or i-line and thus, a new lithography technology using far ultraviolet rays, KrF or ArF excimer laser, X-ray and electron beam have drawn keen attention.
In the case of an ultraviolet ray such as i-line that has been mainly used in the conventional lithographic process, its micro-processing at the subquarter(0.25) micron level is reported to be extremely difficult. Therefore, to achieve the micro-processing at the subquarter micron level, an excimer laser with more short wavelength at the far ultraviolet rays can be utilized, together with X-ray and electron beam; among them, KrF or ArF excimer laser is being spotlighted from the related field.
A resist (hereinafter referred to as “chemically amplified resist”) composition suitable for such excimer laser comprises a component having functional groups acid-decomposable (polymer), a component generating by irradiation (hereinafter referred to as “acid generator”) and a solvent, which is being applied in the lithographic process using the chemically amplified effect induced by the acid generator.
In line with the chemically amplified resist composition, the Japanese Pat. Heisei 2-27,660 has disclosed a resist composition comprising a polymer with t-butyl ester group of carboxylic acid or t-butylcarbonyl group of phenol, together with an acid generator. This method using the composition is based upon the principle that since t-butyl ester group or t-butylcarbonyl group in a polymer is dissociated and calibrated into hydroxyl group due to the action of acid generated from irradiation, the exposed regions are easily dissolved by an alkaline developer.
However, in the case of the chemically amplified resist used for KrF excimer laser, a phenol resin has been mostly employed as a base material but it has proven to be insuitable for a matrix resin due to the fact that the aromatic ring in the resin absorbs much more light from ArF excimer laser. To comply with this matter, intensive research for polyacrylate derivatives as a matrix resin has been made, since it has relatively less absorption of light than phenol resin at ArF excimer laser region (Japanese Pat. Heisei 4-226,461 and Proc. SPIE, 1996, vol. 2724, p. 377).
Even though it has less absorption of light at ArF excimer laser region, polyacrylate has a poor dry etch resistance. Recently, to withcome such drawback of polyacrylate, much research has focused on the method of introducing alicyclic derivatives to polyacrylate in order to enhance the etch resistance but the affinity to a developer is decreased due to the fact that such alicyclic derivatives are hydrophobic. Further, to form the pattern of less than 0.2 micron, the adhesion between a resist composition and substrate is an important factor. In the case of the conventional polyacrylate matrix resin, carboxylic acid is introduced to the side chain of polyacrylate in an effort to improve the adhesion (Proc. SPIE, 1997, vol. 3049, p. 126). However, if the amount of carboxylic acid is increased to some extent, the increasing solubility to a basic solution makes it inevitable to change the basic concentration of a developer.
The matrix resin with hydrophilic groups, which can serve to improve a dry etch resistance, include a copolymer of maleic anhydride and olefin (Proc. SPIE, 1997, vol. 3049, p. 92). With its hydrophilic property, maleic anhydride can serve to facilitate the co-polymerization with an olefin-based monomer at a very low temperature and pressure. The olefin-based monomer can promote a dry etch resistance and resolution through the introduction of various substituents at the side chain of the copolymer (Proc. SPIE, 1998, vol. 3333, p. 463). Further, to overcome the shortcomings that the copolymer resin using maleic anhydride and olefin-based monomer has encountered (e.g., reduction of remaining film characteristics, decrease of dry etch resistance or occurrence of standing wave (
?) in forming the patterns), the recent method of using a low molecular additive for the manufacture of a resist has been greatly spotlighted (Korea Pat. No. 98-064842 and Proc. SPIE, 1998, vol. 3333, p. 73).
SUMMARY OF THE INVENTION
An object of this invention is to provide a chemically amplified resist composition, which is activated by far ultraviolet rays represented by KrF or ArF excimer laser as a chemically amplified resist, and with its excellent transparency on ArF excimer laser beam, the composition has excellent combination of properties such as resolution and sensitivity, including substrate adhesion, dry etch resistance and development properties.
To achieve the above object, the chemically amplified resist composition of this invention is characterized by the chemical composition containing a multi copolymer copolymer represented by the following formula 1, a low molecular additive represented by the following formulae 2 or 3, an acid generator and a solvent.
wherein the repeating units comprising X and Y are independent monomers, respectively, selected from the group consisting of the following formulae (II), (III) and (IV);
wherein R
1
is a hydrogen atom, a linear or branched alkyl group, a cyclic or polycyclic alkyl group, an alkyl carbonyl group, a branched alkyl carbonyl group, a cyclic or polycyclic alkyl carbonyl group of 1 to 20 carbon atoms such as an acetyl group, a t-butyl oxycarbonyl group, a cyclohexane carbonyl group, an adamantane carbonyl group a bicyclo[2,2,1]heptane methyl carbonyl group.
R
2
is a hydrogen atom, a hydroxyl group, carboxylic group, an alkyl group, an alkyl group containing an alkoxy group, a hydroxyl group or a carboxylic acid, an alkoxy group, a linear alkyl oxycarbonyl group, a branched alkyl oxycarbonyl group, an alkoxy alkyl carbonyl group, a cyclic alkyl oxycarbonyl group or polycyclic alkyl oxycarbonyl group of 1 to 20 carbon atoms.
R
3
is a hydrogen atom, a linear or branched alkyl group, a cyclic or polycyclic alkyl group of 1 to 20 carbon atoms such as a methyl group, an ethyl group, a t-butyl group, an isopropyl group, an adamantyl group, a bicyclo[2,2,1]heptane methyl group.
l, m, n and o, which represent the repeating units of a polymer, are 0≦l/(l+m+n+o)≦0.5, 0≦m/(l+m+n+o)≦0.5, 0≦n/(l+m+n+o)≦0.35 and 0.4≦o/(l+m+n+o)≦0.6, respectively, with a value of 0.15≦(1+m)/(l+m+n+o)≦0.5.
wherein R
1
is the same as defined above.
wherein R
2
, R
3
is the same as defined above.
DETAILED DESCRIPTION OF THE INVENTION
To further improve various shortcomings of the conventional chemically amplified positive resist in terms of a substrate adhesion, dry etch resistance and development, the inventor et al. have endeavored
Kim Seong Ju
Park Joo Hyeon
Park Sun Yi
Seo Dong Chul
Baxter Janet
Clarke Yvette M.
Davidson Davidson & Kappel LLC
Korea Kumho Petrochemical Co. Ltd.
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