Inductively coupled plasma reactive ion etching of CoZrNb magnetic thin films was studied using a TiN hard mask in a Cl-2/O-2/Ar gas mix. The etch rates of CoZrNb films and TiN hard mask gradually decreased with increasing Cl-2 O-2 gas concentrations. When O-2 gas was added in the Cl-2/Ar gas mix, the etch rate of TiN hard mask was suppressed effectively so that the etch selectivity of CoZrNb film to TiN hard mask was enhanced. The addition of O-2 into the gas mix also led to the anisotropic etching of the CoZrNb films and it was confirmed by Auger electron spectroscopy that there were no redeposited materials on the sidewall of the etched films. Highly anisotropic etching of CoZrNb films was achieved at room temperature under the optimized etching conditions. (c) 2005 Elsevier B.V. All rights reserved.