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Proceedings Paper

Reactivity of model compounds of ArF immersion, ArF, and KrF resists with diphenylsulfinyl radical cation, a cage-escape product of photochemistry of triphenylsulfonium salts
Author(s): Yoshinori Matsui; Hidekazu Sugawara; Shou Tsuji; Toshiro Itani; Shu Seki; Takahiro Kozawa; Seiichi Tagawa
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Paper Abstract

Reactivity of diphenylsulfinyl radical cation (Ph2S.+) with model compounds of "dry/wet" ArF resists and KrF resists was investigated by pulse radiolysis technique, in order to reveal the reaction between Ph2S.+ and a polymer. Ph2S.+ is an intermediate of photolysis of triphenylsulfonium salts. Some Ph2S.+ react with other intermediate of phenyl radical, leading to the formation of (phenylthio)biphenyl products and proton (H+). The reaction, referred to as rearrangement reaction, is mainly responsible for acid generation. However, some Ph2S.+ react with a polymer. Acid-generation efficiency might be enhanced if H+ is also formed by this reaction. Among 25 model compounds employed, Ph2S.+ was scavenged by phenolic compounds which have lower electrochemical half wave reduction potential (E1/2) than that of Ph2S. However, resulting radical cations of the phenolic compounds were not observed. Ph2S.+ was not scavenged by the other compounds with higher E1/2. Decay rate constant of Ph2S.+ scavenged by additives clearly depends on the change of E1/2 between Ph2S and the additives including pyrene from which charge transfer was observed to Ph2S.+. The reaction is therefore charge transfer between the model compounds and Ph2S.+. The resulting radical cations of phenolic compounds are known to decompose to phenoxy radical and proton (H+), suggesting that the compounds contribute to the enhancement of acid-generation efficiency in a chemically amplified resist. From the viewpoint of reaction of Ph2S. + with resists, conventional polymer of KrF resist is therefore appropriate for H+ source. Phenolic compounds are generally not appropriate for the component of "dry/wet" ArF resists because of their strong absorption at 193 nm. However, the electron proved to be transferred from fluorinated methylphenols to Ph2S.+. Fluorinated methylphenols may have a potential for candidate of resist components improving acid generation in "dry/wet" ArF lithography.

Paper Details

Date Published: 11 April 2006
PDF: 12 pages
Proc. SPIE 6153, Advances in Resist Technology and Processing XXIII, 61530I (11 April 2006); doi: 10.1117/12.655087
Show Author Affiliations
Yoshinori Matsui, Osaka Univ. (Japan)
Hidekazu Sugawara, Osaka Univ. (Japan)
Shou Tsuji, Semiconductor Leading Edge Technolgies, Inc. (Japan)
Toshiro Itani, Semiconductor Leading Edge Technolgies, Inc. (Japan)
Shu Seki, Osaka Univ. (Japan)
Takahiro Kozawa, Osaka Univ. (Japan)
Seiichi Tagawa, Osaka Univ. (Japan)

Published in SPIE Proceedings Vol. 6153:
Advances in Resist Technology and Processing XXIII
Qinghuang Lin, Editor(s)

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