Gettering rates of various fast-diffusing metal impurities at ion-damaged layers on silicon

Abstract

High-temperature gettering of Fe, Co, Ni, Cu, and Au by ion-damaged surface layers on silicon wafers has been studied by Rutherford backscattering of 4He+ ions incident at 1.75 or 2 MeV. Analysis showed impurity levels in the damaged layers ranging from 1013–1017/cm2. The metals fall into two groups: those which are gettered slowly-Fe, Co, and Au— and those gettered rapidly-Cu and Ni. This trend is predicted by a simple diffusion model using published interstitial solubilities and diffusivities.