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 18O isotope and subsequent determinations of the 18O profiles. After sequential 16O2 / 18O2 or 18O2 / 16O2 oxidations of SiC, the 18O 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 18O depth distributions in samples oxidized in a single step in 18O-enriched O2. A probable explanation for this gradual SiO2 /SiC interface is shown to be the formation of C clusters during oxidation.