Anomalous high rate reactive ion etching process for indium tin oxide

An anomalous high indium tin oxide etch rate, i.e., 1630 angstroms/min, reactive ion etching condition has been obtained. This process is based on the combination of high temperature, i.e., 250 °C, and a mixture of HCl and CH4 gases. Throughout the whole range of the gas composition, the highest etch rate is obtainable in a small CH4 concentration range, e.g., around 40%. The same phenomenon has been observed at different plasma powers. The influence of temperature or power to the etch rate is not obvious unless a threshold temperature or a threshold power is surpassed. The pure HCl plasma etched surface is in liquid form and has a rough topography after solidification. The HCl/40% CH4 etched surface is solid and has a smooth topography. A high etch rate is contributed by near-stoichiometric surface reactions as well as strong ion bombardment.