Plasma etching of RuO2 thin films was studied. It was shown that reactive ion etching employing CF4 or O2 plasma is effective in delineating RuO2 fine patterns. The etching rate was 2̃ 5 times higher than that for sputter etching. A higher etching rate and good selectivity were achieved using O2 plasma. This result can be explained by the difference in volatility of the respective reaction species.