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Proceedings Paper

Chemical durability studies of Ru-capped EUV mask blanks
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Paper Abstract

Surface cleaning has become one of the most critical processes in photomask manufacturing in the last few years because of the demands for high cleaning efficiency with no film loss and no damage to fragile patterns. The requirement is getting tighter as the feature-size shrinks. In addition, EUV masks pose further unique challenges in the cleaning process, because of the reflective multilayer (ML) mask structure, which is sensitive to surface damage, and a more frequent cleaning requirement due to the lack of pellicle protection during handing and usage. To address the challenge of ML surface damage from EUV mask cleaning processes, this paper presents the chemical durability of Ru-capped ML blanks against two types of chemistries: a mixture of sulfuric acid and hydrogen peroxide (SPM) and ozonated water (DIO3). The authors found that SPM slightly oxidized the Ru capping layer, but with minimal effect to EUV reflectivity. It was observed that DIO3 damaged the Ru capping layer and resulted in a significant EUV reflectivity drop. An alloyed Ru-capping layer showed improved durability against DIO3 damage. The changes to the Ru-surface were characterized with atomic force microscopy (AFM) and X-ray photo electron spectroscopy (XPS).

Paper Details

Date Published: 17 October 2008
PDF: 8 pages
Proc. SPIE 7122, Photomask Technology 2008, 712226 (17 October 2008); doi: 10.1117/12.803065
Show Author Affiliations
Takeya Shimomura, Dai Nippon Printing Co., Ltd. (Japan)
Ted Liang, Intel Corp. (United States)

Published in SPIE Proceedings Vol. 7122:
Photomask Technology 2008
Hiroichi Kawahira; Larry S. Zurbrick, Editor(s)

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