The etch characteristics of Al2O3 films were investigated for magnetically enhanced reactive ion etching (MERIE) and inductively coupled plasma (ICP) etch systems as a function of bias power, source power, and gas chemistry. Compared to pure Ar sputtering, F-, Cl-, and Br-based plasma provided a significant chemical enhancement. Fluorine containing plasma produced higher etch rates compared to Cl and Br. The selectivity for Al2O3 over other semiconductor materials is low for all of the investigated two-gas mixtures. A polymerizing C4F6 chemistry provides acceptable selectivity to Si, and was used for a patterning of an Al2O3 hard mask. These structures have been transferred into the Si wafer. (c) 2005 The Electrochemical Society. All rights reserved.