AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS-ThP

Paper SS-ThP9
Thermal- and Electron-Induced Reactions on the Ru(10-10) Surface: Relevance to Extreme Ulltraviolet Lithography

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: T.E. Madey, Rutgers University
Authors: T.E. Madey, Rutgers University
B.V. Yakshinskiy, Rutgers University
R. Wasiliewski, Rutgers University
Correspondent: Click to Email
Our goal is to provide insights into surface processes that affect the reflectivity of Ru-coated mirrors used in extreme ultraviolet (EUV) lithography applications. Thin capping layers of Ru are found to reduce contamination and oxidation of Mo/Si multilayer reflecting optics surfaces, and extend the useful lifetime of EUV multilayer mirrors. However, reflectivities of even the Ru-coated mirrors degrade in time during exposure to vacuum background gases and EUV radiation. Several techniques, including temperature programmed desorption (TPD), x-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS) and electron stimulated desorption (ESD), are used to characterize thermally-induced and electron impact-induced surface reactions of gases found typically in vacuum chambers of EUV lithography systems. We present data concerning the interaction of water and acetone vapors with clean, O-covered and C-covered Ru(10-10) surfaces. A 100eV electron beam is used to mimic excitations initiated by 13.5 nm wavelength radiation employed in EUV applications. The data show non-wetting behavior of water on the air-exposed or the carbon-covered surfaces; however, water becomes more strongly bonded to an oxygen-dosed substrate. We report on the electron-induced dissociation and desorption of water adsorbed on these surfaces at low temperature. The clean Ru surface is shown to be easily covered by carbon as a result of the thermally-induced dissociation of acetone, but this reaction demonstrates different behaviour on the preoxidized Ru. Electron-stimulated desorption of O from Ru proceeds at electron energies > 25eV. Our results may provide insights into contamination and mitigation processes that affect EUV mirror lifetimes.@footnote 1@ @FootnoteText@ @footnote 1@ T. E. Madey, B. V. Yakshinskiy, N. S. Faradzhev, N. V. Edwards, Appl. Surf. Sci. (2006), in press.