Rapid Oxidation of Silicon Using UV-Light Irradiation in Low-Pressure, Highly Concentrated Ozone Gas below 300 °C

Abstract

A low-temperature, damage-free process for growing ultrathin (<6 nm) silicon dioxide (SiO2) films was successfully developed. The excitation of low-pressure, highly concentrated O3 gas using photons with energies less than 5.6 eV led to rapid growth rates of 2 and 3 nm within 1 and 5 min, respectively, even when the process temperature was as low as 200 °C. The enhanced oxidation rate was due to an increased supply of O(1D) atoms at the Si surface. Transmission electron microscope images revealed that the SiO2 film formed with a uniform thickness and a smooth, distinct SiO2/Si interface. Capacitance–voltage and current–voltage measurements showed that 200 and 300 °C as-grown films had a satisfactorily low density of mobile ions and trap charges as well as ideal insulating properties.