A low-temperature and low-activation-energy process for the gate oxidation of Si substrates has been proposed. Using the energy-controlled excited oxygen generated in rare-gas and O2 molecule mixture plasma, the enhancement of the oxidation rates was achieved. In addition, the oxidation rates and kinetics drastically change with the type of mixed rare gas in the plasma. Using Kr as the mixed rare gas, the interface trap density near the mid gap [D it(mid)] of the SiO2/Si interface grown at 500°C was 2.6×1011/cm2/eV, which was comparable to that of the as-grown one using conventional thermal oxidation at a higher temperature. For this process, the oxidation rates were shown to be hardly dependent on the substrate temperature, and the activation energy of B, which is the parabolic rate constant, was found to be low, 0.14 eV.