Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Metal subtrates: Adsorption of O and/or H

O 27.3: Vortrag

Dienstag, 23. März 2010, 11:00–11:15, H42

Oxidation kinetics of Ru(0001) — •Marius Ernst¹ and Wim Sloof² — ¹Universität Würzburg, Experimentelle Physik 7 — ²Delft University of Technology, Department of Materials Sciences

Ru is a candidate material to be used as protective capping layers on mirrors for extreme ultraviolet (EUV) lithography. These mirrors are subject to contamination due to reaction of the mirror surface with hydrocarbons and oxygen under influence of the EUV radiation. In order to find a method of mitigating the effects of this contamination, it is necessary to understand the interaction process of the contaminating species and the Ru mirror surface. In this study the oxidation kinetics of a monocrystalline Ru(0001) surface was studied with ellipsometry and XPS. During the oxide growth, first a monolayer of chemisorbed oxygen was formed on the surface. After this monolayer was formed in its entirety, ruthenium dioxide could start to grow. The change from the chemisorbed oxygen layer to RuO₂ is related to a phase transition from a (1x1) overlayer structure to the (110) plane of RuO₂ and only occurs after a constant exposure of the Ru(0001) surface to oxygen. In the second stage the growth of RuO₂ is linear with time, indicating an adsorption limited growth mode. Finally, in the third stage, the growth levels off due to a transport limited behavior. The EUV light can accelerate the transition from the chemisorbed monolayer to RuO₂ but has no significant effect on the thickness and structure of the oxide after longer oxidation times.