Nonplanar silicon oxidation in dry O2+NF3

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Abstract
Nonplanar silicon oxidation in a dry O2+NF3 gas mixture has been investigated. Oxide morphologies at silicon corners following 800 °C oxidation in dry O2 and in dry O2+NF3 gas 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/SiO2 interface is smoothly rounded off at the corners following oxidation in dry O2+NF3. The effects of adding NF3 gas to a dry O2 atmosphere on nonplanar oxidation are discussed. Furthermore, a sacrificial oxidation in dry O2+NF3 prior to forming the thin capacitor oxide is found to be very effective for reducing the oxide leakage current for a trenched capacitor.