Rapid photo-oxidation of silicon at room temperature using 126 nm vacuum ultraviolet radiation

Abstract

Over the years, photo-oxidation of silicon has been found to proceed fastest when the progressively lower wavelength radiation has been used. Here, we use the shortest UV lamp radiation yet applied to Si oxidation, by employing 126 nm radiation from an Ar excimer lamp source. Oxidation rates as high as 5 nm/min were readily achievable at room temperature, which are more than two orders of magnitude higher than those for UV-induced oxidation of silicon using a low pressure mercury lamp at a temperature of 350 °C, and immeasurably higher than for thermal oxidation at room temperature. This enhancement is believed to arise from two effects: ozone produced by 126 nm light and more efficient photochemical reaction at lower wavelengths. Furthermore, thicknesses up to 9 nm have been obtained, which are not possible in reasonable times with conventional dry thermal oxidation processes at temperatures less than even 500 °C. The films are found by XPS and FTIR to be stoichiometric in nature. Current–voltage measurements from metal oxide–semiconductor (MOS) devices fabricated using a 9 nm SiO 2 layer showed that leakage current densities as low as 10 −6 A/cm 2 at an electric field of 1 MV/cm can be obtained in the as-grown films. Further properties of these films will be reported.