Etching characteristics (etch rate, selectivity and etching profile) of YMnO3 thin films were investigated using CF4/Ar inductively coupled plasma. The maximum etch rate of 18 nm/min for YMnO3 thin films was obtained at CF4(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 At addition. The chemical states of YMnO3 films exposed to the plasma were investigated using X-ray photoelectron spectroscopy and secondary ion mass spectrometry (SIMS). Metal-fluorides such as YF YF2, YF3 and MnF3 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 65degrees and the surface was clean. (C) 2003 Elsevier Science B.V. All rights reserved.