Jpn. J. Appl. Phys. 44 (2005) pp. 114-117 |Previous Article| |Next Article| |Table of Contents|
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Dry Etching of Cr2O3/Cr Stacked Film during Resist Ashing by Oxygen Plasma
Junichi Tonotani, Shun-ichiro Ohmi1 and Hiroshi Iwai2
Corporate Manufacturing Engineering Center, Toshiba Corporation, 33 Shin-Isogo-cho, Isogo-ku, Yokohama 235-0017, Japan
1Department of Information Processing, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
2Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
(Received May 1, 2004; accepted October 8, 2004; published January 11, 2005)
Stacked films of chromium oxide and chromium (Cr2O3/Cr) have been commonly used as a photomask for the lithographic process of integrated circuit fabrication. It has been found, however, that the Cr2O3/Cr films were etched during the oxygen plasma ashing process, which is applied for the resist removal after the Cr2O3/Cr patterning. In order to solve this problem, we investigated the mechanisms of the Cr2O3/Cr film etching during the ashing process. As a result, it was found that the Cr2O3/Cr film is oxidized during the ashing process to generate CrOx (2≤x≤3) in which Cr has a higher valence than Cr2O3, and that the CrOx (2≤x≤3) evaporates. It was confirmed by means of a plasma shielding experiment that not only oxygen plasma but also oxygen radicals oxidize the Cr2O3/Cr. It has been found that keeping the photomask temperature below 200°C during the ashing process solves the Cr2O3/Cr etching problem.
KEYWORDS:
chromium, chromium oxide, etching, ashing, oxygen, plasma, photomask
URL:
http://jjap.ipap.jp/link?JJAP/44/114/
DOI: 10.1143/JJAP.44.114
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