Thermal processes used in EUV optics contamination mitigation

3 Thermal processes used in EUV optics contamination mitigation 

Thermal processes used in EUV optics contamination mitigation are processes in which heat is used to either inhibit or clean off contaminants, without introducing a new set of problems. Taking a Ru-capped EUV multilayer reflector as our target surface, we examine here aspects of the surface reactions involved in removing carbon deposits and surface oxides from model Ru and Ru02 surfaces. 

Takase, S. Terashima, Y. Gomei, M. Tanabe, Y. Watanabe, T. Aoki, K. Murakami, S. Matsunari, M. Niihe, and Y. Kakutani, Study of ruthenium capped multilayer mirror for EUV irradiation durability, Proc. SPIE 6151, 615135 (2006). 

A good starting point is the investigation of Koch et involving the water- 

Atomic hydrogen is effective at removing adsorbed O from a Ru(OOOl) surface at low temperatures. Weinberg and co-workers have demonstrated that as gas-phase H atoms (produced by dissociation of H2 on a hot W wire) impinge on a 0.5 monolayer of oxygen at surface temperatures below 100 K, they react directly to form surface OH ions via the Eley-Rideal mechanism, in which the H atoms react with O before being accommodated on the surface. The OH ion eventually reacts with the H atom to form water, which readily desorbs from the surface as the latter warms up (at temperatures greater than 200 K). 

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