Demonstration of non-negligible oxygen exchange in the thermal oxidation of silicon carbide

Abstract

Oxygen incorporation mechanism with various temperatures during the thermal oxidation of 4H–SiC in dry O2 has been investigated by the isotopic tracing technique. The results suggest that the oxygen exchange is the main incorporation mechanisms of oxygen for SiC oxidation. The temperature and locations of oxygen exchange are different from those in Si oxidation. In SiC thermal oxidation, oxygen exchange occurs even for extremely low oxidation rate at low temperature, and it is not confined to the surface region but throughout the oxide layer. The rate of oxygen exchange increases as temperature increases. This is the direct evidence that oxygen exchange in SiC oxidation cannot be negligible. By analysing the results of X-ray photoelectron spectroscopy and capacitance-voltage measurements, it is found that such significant oxygen exchange is not caused by a large number of defects. Moreover, based on the fitting of refractive index and extinction coefficient, the number of defects in the oxide layer decreases with the increase of temperature, which indicates that oxygen exchange contributes to reducing defects in the oxide layer during high-temperature oxidation and low-temperature post-oxidation annealing.