The dry etch behavior of Pt films using a TiO2 hard mask was investigated with an O-2/Cl-2/Ar gas chemistry in an inductively coupled plasma. The variations in etch rates and etch profiles of both the Pt films and the TiO2 masks were examined as a function of Cl-2 and O-2 concentration. It was found that the ratio of O-2 to Cl-2 concentration strongly influenced the etch selectivity of the Pt film relative to the TiO2 mask. X-ray photoelectron spectroscopy indicates that the addition of O-2 to the gas mix causes a decrease in the TiO2 etch rate as a result of the oxidation of Ti2O3 and TiO species. It is proposed that these oxides arise via the reduction of TiO2 in the presence of a Cl-2/Ar plasma. A 1 mu m x 1 mu m minimum feature size was successfully etched with this TiO2 mask material, yielding a sidewall of approximately 75 degrees in slope that did not exhibit redeposition or residue.