A low-temperature and high-purity radical-assisted oxidation (RAO) process for the growth of ultrathin (1.4-2.3 nm) gate oxides was successfully developed utilizing a remote ultraviolet ozone source. The metal-oxide- semiconductor transistors with RAO gate oxides showed improved device characteristics and oxide reliability, in comparison with the devices with non-RAO or standard furnace oxides. The RAO process in this study was proven to be an effective technique to make the oxide network robust and dense, without an increase of growth temperature. (C) 2004 American Vacuum Society.