The influence of ion implantation on the thermal oxidation of copper

Abstract

The effect of ten species of ion-implanted impurities on the thermal oxidation of copper has been studied. The majority of these increased the oxidation resistance of the copper, the greatest effect (85% decrease in oxidation) being caused by Ti. Only Xe and Cs caused significantly increased oxidation in dry oxygen, but in the presence of water vapour the effect of Ti⁺ implants was reversed and increases in oxidation rate up to 100% were observed. Electrical measurements on devices formed by applying a gold probe to the oxide surface showed a correlation between switching voltage and the effect of the implant on the oxidation rate. A simple model is proposed whereby the observed behaviour is ascribed to the creation of an n type region in the predominantly p type oxide such that inward hole diffusion is inhibited during oxide growth.