Investigation of silicon etching and silicon dioxide bubble formation during silicon oxidation in HCl-oxygen atmospheres

Experiments performed to characterize the silicon etching occurring at the silicon-silicon dioxide interface during thermal oxidation of silicon in dry oxygen-HCl atmospheres at 1100 °C are described. The etching was accompanied by bubble formation or bowing of the silicon dioxide film and ultimately by complete loss of adhesion of the thermally grown film. Pre-oxidation experiments with dry oxygen suggest that silicon etching is primarily dependent upon the chlorine concentration at the silicon-silicon dioxide interface, with oxide growth prior to HCl addition having a small effect.