A silicon on insulater (SOI) wafer is provided. A dielectric layer is formed on an active silicon substrate of the wafer. The dielectric layer is patterned and etched to expose selected portions of the silicon substrate. Impurities are then introduced into the exposed portions of the silicon substrate to act as gettering regions. The dielectric layer is then removed and an epitaxial layer of silicon is grown on the silicon substrate. Trenches are etched in the epitaxial layer of silicon through the gettering regions, partially removing the gettering regions and any contaminants contained therein. Remaining portions of the gettering regions still act as gettering regions during subsequent process steps.