Dry etch chemistries for TiO2 thin films

Several different plasma chemistries were investigated for dry etching of TiO2 thin films. Fluorine-based discharges produced the fastest etch rates (∼2000 Å min−1) and selectivities >1 for Si over TiO2. Chlorine-based discharges also showed a chemical enhancement over pure Ar sputtering and had selectivities <1 for Si over TiO2 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 TiO2 were excellent in all three types of plasma chemistry. Small concentrations (2 at.%) of chlorine- or fluorine-containing residues were identified on the TiO2 surface after Cl2/Ar or SF6/Ar etching, but these residues were water soluble.