Oxidation and Reduction of Ultrathin Nanocrystalline Ru Films on Silicon:  Model System for Ru-Capped Extreme Ultraviolet Lithography Optics

Ultrathin ruthenium films are promising capping layers protecting extreme ultraviolet lithography optics against carbon growth and oxidation. The structure and reactivity of 2, 5, and 7 nm thick nanocrystalline Ru films on Si (serving as a model system for Ru capping layers) were studied by multiple...

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Bibliographic Details
Published in:Journal of physical chemistry. C 2007-07, Vol.111 (29), p.10988-10992
Main Authors: He, Y. B, Goriachko, A, Korte, C, Farkas, A, Mellau, G, Dudin, P, Gregoratti, L, Barinov, A, Kiskinova, M, Stierle, A, Kasper, N, Bajt, S, Over, H
Format: Article
Language:English
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Summary:Ultrathin ruthenium films are promising capping layers protecting extreme ultraviolet lithography optics against carbon growth and oxidation. The structure and reactivity of 2, 5, and 7 nm thick nanocrystalline Ru films on Si (serving as a model system for Ru capping layers) were studied by multiple techniques including scanning electron microscopy, X-ray diffraction, X-ray reflectivity, and X-ray photoelectron spectroscopy. The structural analysis indicated dense and flat Ru films, consisting of preferentially (0001)-oriented grains. High resolution core-level Ru 3d5/2 and O 1s spectroscopy studies have revealed that these Ru films exposed to O2 ambient are resistant to oxidation up to ∼470 K similar to the oxidation of single-crystalline Ru(0001) surfaces. The reduction of the oxide in the H2 ambient is highly effective and proceeds already below 370 K.
ISSN:1932-7447
1932-7455
DOI:10.1021/jp071339b