Effect of atomic and molecular hydrogen on the reduction process of ruthenium dioxide

Gaining insights into the reduction process of ruthenium dioxide by atomic hydrogen is relevant for the optimization of the lifetime of the optics of extreme ultraviolet nanolithography machines. This thesis reports an in situ X-ray photoelectron spectroscopy (XPS) study of the different effect that atomic vs molecular hydrogen has on the reduction of ruthenium dioxide. The results presented in this research demonstrate that reduction of RuO2 using H* leads to a more effective and faster reduction of the oxide layer than through H2. A detailed study of the evolution of the oxygen species involved in this reaction, oxide, hydroxide, and adsorbed water is reported. A systematic difference of the evolution of these 3 oxygen species during reduction with H* and H2 is identified .