Thermodynamic considerations in refractory metal-silicon-oxygen systems

Abstract

Thermodynamic considerations in thin-film reactions involving refractory metals, refractory metal silicides, silicon, and silicon dioxide are described using ternary phase diagrams. Calculated metal-silicon-oxygen phase diagrams for Mo, W, Ta, and Ti are used to explain the reactivity of the metal with silicon dioxide, the effectiveness of native oxide in preventing metal-silicon interdiffusion, and the formation of silicon dioxide in preference to metal oxides during silicide oxidation. Distinctions are drawn between experimental results which can be explained solely on thermodynamic grounds and those requiring consideration of both thermodynamic and kinetic factors.