C. G. Morgan and R. Vane, XEI Scientific, Inc., Redwood City, CA
Poster Presentation at SPIE Advanced Lithography Conference, March 2011, San Jose, CA

Carbon contamination on extreme ultraviolet (EUV) optics reduces their reflectivity. The use of a commercially available low power downstream plasma cleaner using room air has been shown to be effective in removing carbon contamination from EUV optics. However,there is concern that removal of carbon contamination by oxidation may damage the capping layers of the optics. In particular, ruthenium capping layers may be susceptible to reaction with oxygen radicals. The previous experiments with low power downstream plasma were done on silicon capped EUV optics. In this paper, the use of gases other than room air, such as hydrogen with low power downstream plasma cleaning is explored to determine its effectiveness by using customized quartz crystal monitors.

View PDF document here.