Nonplanar silicon oxidation in a dry O2+NF3gas mixture has been investigated. Oxide morphologies at silicon corners following 800 °C oxidation in dry O2and in dry O2+NF3gas are observed using a scanning electron microscope. While a serious decrease in oxide thickness at convex silicon corners is observed following oxidation in dry O2, no inhibition of oxide growth occurs and the Si/SiO2interface is smoothly rounded off at the corners following oxidation in dry O2+NF3. The effects of adding NF3gas to a dry O2atmosphere on nonplanar oxidation are discussed. Furthermore, a sacrificial oxidation in dry O2+NF3prior to forming the thin capacitor oxide is found to be very effective for reducing the oxide leakage current for a trenched capacitor.