Etching characteristics (etch rate, selectivity and etching profile) of YMnO 3 thin films were investigated using CF 4 /Ar inductively coupled plasma. The maximum etch rate of 18 nm/min for YMnO 3 thin films was obtained at CF 4 (20%)/Ar(80%) gas mixing ratio. Optical emission spectroscopy analysis was performed to analyze the behavior of active species as a function of gas mixing ratio and showed decreasing volume density of fluorine atoms during Ar addition. The chemical states of YMnO 3 films exposed to the plasma were investigated using X-ray photoelectron spectroscopy and secondary ion mass spectrometry (SIMS). Metal-fluorides such as YF, YF 2 , YF 3 and MnF 3 were detected using SIMS analysis. Ion assisted chemical etching was proposed as the main etching mechanism. At the process conditions, which correspond to maximum etch rate, the etch slope was approximately 65 o and the surface was clean.