Reactive Ion Etching of Titanium Tungsten Thin Films

Abstract

Reactive ion etching processes on titanium tungsten thin films have been investigated with , , and feed gases. Process parameters such as feed gas composition, radio-frequency power, and pressure showed tremendous effects on the etch rate and the etch selectivity. Both F and Cl are effective etchants for the titanium tungsten film. The etch rate is chemically controlled by the F concentration in the plasma, and by the sum of Cl and F concentrations in the and plasmas. The etch rate is a function of both the plasma phase etchant concentration and the ion bombardment energy. The peak etch rate was obtained at the medium pressure range, e.g., , due to the combination of the above two factors. The F residue was detected on the plasma etched surface, while a trace amount of Cl was detected on the plasma etched surface. Although the plasma-enhanced chemical vapor deposition silicon nitride was etchable with the same type of plasma, an etch selectivity of greater than 2 was achieved under the low ion bombardment condition.