SiO2/SiC structures annealed in D2 18O : compositional and electrical effects

Abstract

Effects of water vapor annealing on SiO2/4H-SiC structures formed following different routes were investigated using water isotopically enriched in 18O and 2H (D). Isotopic exchange between oxygen from the water vapor and oxygen from SiO2 films deposited on 4H-SiC was observed in the whole depth of the films, differently from the behavior of SiO2 films thermally grown on 4H-SiC. The highest amount of D was obtained in the sample with the highest negative fixed charge concentration, suggesting that the D incorporation occurs in defects in the structure that exist prior to the annealing. As a consequence of the water annealing, a significant reduction in the negative effective charge in metal-oxide-semiconductor capacitors and the removal of the SiO2/SiC interfacial region was observed, attributed to the reduction of the amount of SiOxCy compounds in the interfacial region.