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Proceedings Paper

Novel strategy for the design of highly transparent ArF resists with excellent dry etch resistance
Author(s): Wenwei Zhao; Takeshi Ohfuji; Masaru Sasago; Seiichi Tagawa
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Paper Abstract

To circumvent the difficulty in seeking a balance between dry etch resistance and the transparency at 193 nm in the design of a single-layer-resist for ArF lithography, a new strategy based on the de-coupling of these two criteria from each other is presented. The possibility of the de-coupling has been demonstrated by imparting dry etch resistance to resist matrix after the exposure step. Imparting of dry etch resistance can be achieved with the utilization of thermal- activated reactions during post exposure bake or plasma- activated reactions during etching. Specifically, copolymers containing acrylonitrile were synthesized and evaluated as a demonstration. Chemical reactions, especially cyclization reaction, in the copolymers upon heating were investigated. Intramolecular cyclization of the nitrile groups, which is electrophilic reagent catalyzed, starts at about 130 degree(s)C in a copolymer of acrylonitrile containing 50 mol% methacrylic acid. The reaction results in rigid ring structures with satisfying dry etch resistance. Dry etch resistance of the copolymer after thermal treatment was measured to be up to the same level of a poly(hydroxystyrene)-based commercial resist. Partially protection of the acid component by introducing tertiary- butyl ester groups provides new chemically amplified resist candidates. The materials based on terpolymers of acrylonitrile, tertiary-butyl methacrylate and methacrylic acid well satisfy the basic requirements for ArF resists with high transparency at 193 nm and excellent dry etch resistance after prolonged post exposure bake. Lithographic performance of the newly designed materials are currently under further assessments..

Paper Details

Date Published: 29 June 1998
PDF: 9 pages
Proc. SPIE 3333, Advances in Resist Technology and Processing XV, (29 June 1998); doi: 10.1117/12.312448
Show Author Affiliations
Wenwei Zhao, Osaka Univ. (Japan)
Takeshi Ohfuji, Association of Super-Advanced Electronics Technologies (Japan)
Masaru Sasago, Association of Super-Advanced Electronics Technologies (Japan)
Seiichi Tagawa, Osaka Univ. (Japan)

Published in SPIE Proceedings Vol. 3333:
Advances in Resist Technology and Processing XV
Will Conley, Editor(s)

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