Oxygen transport and incorporation mechanisms in the dry thermal oxidation of 6H-SiC

Abstract

Thermal oxidation of 6H-SiC was investigated by means of isotopic tracing and narrow nuclear resonant reaction profiling techniques. The mechanisms of oxygen transport and incorporation were accessed by sequential oxidations in dry O2 enriched or not in the O18 isotope and subsequent determinations of the O18 profiles. After sequential O216∕O218 or O218∕O216 oxidations of SiC, the O18 profiles were seen to be markedly different from those observed in Si oxidation, which led to the identification of different mechanisms of oxygen incorporation and transport. The gradual nature of the SiO2∕SiC interface was also evidenced by the O18 depth distributions in samples oxidized in a single step in O18-enriched O2. A probable explanation for this gradual SiO2∕SiC interface is shown to be the formation of C clusters during oxidation.