Oxidation of Si surface by a pulsed Nd: YAG laser

Abstract

SiO2 thin films have been obtained by 1064 nm Nd: YAG laser oxidation of p-Si in the presence of O2. The thickness uniformity, dielectric and electrical properties of the layers have been studied. The effect of both the laser beam energy density and the substrate temperature on the oxide growth is also discussed. It was established that there exists an interval of laser beam energy density in which the oxidation occurs without surface melting. The oxidation process is controlled by the laser beam energy density rather than by the substrate temperature (673-748 K) and the higher laser power results in a thicker oxide. X-ray photoelectron spectroscopy (XPS) was used to provide information on the oxide composition. XPS results revealed that the as-grown oxide is a mixed layer of SiO2 and Si2O, which are distributed nonuniformly through the depth. MOS capacitors fabricated on the grown oxide exhibited typical capacitance-voltage, conductance-voltage characteristics. However, the density of interface states and oxide charge density were found to be higher than the typical values of thermally grown oxides. The quality of the oxide layers can be further improved by optimization of the process parameters and/or by post-processing of the grown films. It is concluded that the SiO2 films formed by the technique of Nd: YAG laser-enhanced oxidation at low temperature are potentially useful for device applications.