Chemical mechanism of oxidative etching of ruthenium: Insights into continuous versus self-limiting conditions

•The mechanisms and conditions required for oxidative etching of Ru is studied.•Oxidative etching of Ru is more favored over that of RuO2.•Oxide formation leads to a reduction in the etching rate.•Etching rate depends on the crystalline orientations of Ru exposed to surface.•Fundamental understanding on oxidation and etching of Ru is provided.