Oxidation and Etching of Thin Ruthenium Films in Low Ion Energy Oxygen Plasma

It has been established by X-ray photoelectron spectroscopy that the oxidation of thin ruthenium films in oxygen plasma with the addition of 5% inert gases (Ar or Kr) occurs to form an oxide layer of RuO2. With an increase in ion energy from 20 to 140 eV, the oxygen content in the near-surface layer was found to increase from 60 to 70 at %. The Ru etching rate also increased several times. Such a symbate dependence is explained by the fact that ion bombardment of the surface stimulates not only the removal of weakly bound metal oxides on the surface but also accelerates their formation on the surface. The limiting stage of etching is the removal of low-volatile metal oxides. The shift of the Ru3d doublet peaks, the change in their relative intensity depending on the ion energy, and the presence of an oxygen-enriched layer on the RuO2 surface indicate that RuO3 oxide can be formed on the surface during plasma treatment.