Dry etch chemistries for TiO 2 thin films

Abstract

Several different plasma chemistries were investigated for dry etching of TiO 2 thin films. Fluorine-based discharges produced the fastest etch rates (∼2000 Å min −1) and selectivities >1 for Si over TiO 2. Chlorine-based discharges also showed a chemical enhancement over pure Ar sputtering and had selectivities <1 for Si over TiO 2 for a range of plasma conditions. Methane–hydrogen discharges produced very slow etch rates, below those obtained with Ar sputtering. The etched surface morphologies of TiO 2 were excellent in all three types of plasma chemistry. Small concentrations (2 at.%) of chlorine- or fluorine-containing residues were identified on the TiO 2 surface after Cl 2/Ar or SF 6/Ar etching, but these residues were water soluble.