In this study, the etch characteristics of IrMn magnetic thin films patterned with TiN hard mask were investigated using an inductively coupled plasma reactive ion etching in CH4/Ar and CH4/O-2/Ar gas mixes. As the CH4 concentration increased in the CH4/Ar gas, the etch rates of IrMn and TiN films simultaneously decreased, while the etch selectivity increased and etch profiles improved without any redeposition. The addition of O-2 to the CH4/Ar gas led to an increase in the etch selectivity and a higher degree of anisotropy in etch profile. The dc-bias voltage and gas pressure were varied to examine and optimize the etching process of IrMn films. Low gas pressure and high dc-bias voltage improved the etch profile, which displayed a high degree of anisotropy. Surface analysis of etched films by X-ray photoelectron spectroscopy was performed to identify the existence of compounds during etching. (C) 2011 Elsevier B. V. All rights reserved.