Study of defects distribution in SiO2/SiC with plasma oxidation and post oxidation annealing

Abstract

Microwave plasma oxidation is a method to realize high quality SiC gate oxide instead of thermal oxidation. In order to achieve good dielectric reliability by microwave plasma oxidation, the defects distribution in the oxide layer after post oxidation annealing (POA) have been studied. The deconvolution of X-ray photoelectron spectroscopy (XPS) spectra at different distances from the interface were analyzed to obtain the distribution of oxygen deficiency throughout the entire oxide layer. POA treatment has been confirmed to decrease oxygen deficiency. Besides, the distribution trend of oxygen vacancies near the interface by secondary ion mass spectrometry analysis is consistent with the XPS results. Considering the reaction between oxygen vacancy and oxygen atom, a kinetic model was proposed to explain the repair mechanism. This explanation is further confirmed by a series of electrical characterization, such as the leakage current density, time-dependent dielectric breakdown, the density of interface traps, border trap and fixed charge of SiO2/SiC stacks. The variation of these electrical properties with annealing temperature is consistent with the variation of oxygen vacancy with annealing temperature.