Low-temperature SiO2 growth using fluorine-enhanced thermal oxidation

Abstract
A new low‐temperature oxidation technique of silicon to obtain high quality Si‐SiO2 interface and bulk SiO2 layer is presented. A few tens‐nanometer‐thick oxide layers are grown within 30 min at temperatures between 600 and 800 °C by fluorine‐enhanced thermal oxidation using an O2+NF3 gas mixture. Fluorine atoms incorporated in the oxide layer are substituted by oxygen atoms through post‐annealing in pure oxygen gas at the same temperature as oxidation. An interface state density as low as 2×1010 cm2 eV1 near midgap is achieved for oxides grown at 800 °C and 8×1010 cm2 eV1 even for oxides at 600 °C. The dielectric breakdown strength of the oxide is improved by the post‐annealing in O2.