Effects of chlorine on interfacial properties and reliability of SiO2 grown on 6H-SiC

A new process of oxidizing 6H-SiC in dry O2+trichloroethylene (TCE) is used to incorporate chlorine in SiO2. The interface quality and the reliability of 6H-SiC MOS capacitors with gate dielectrics prepared by the process are examined. As compared to the conventional dry O2 oxidation, the O2+TCE oxidation results in lower interface-state density, reduced oxide-charge density and enhanced reliability. This could be attributed to the passivation effects of Cl2 and HCl on the structural defects at/near the SiC/SiO2 interface, and also their gettering effects on ion contamination. Moreover, post-oxidation NO annealing, especially in a wet ambient, can further decrease the interface-state density and the oxide-charge density. Lastly, an increased oxidation rate induced by TCE is observed and should be useful for reducing the normally high thermal budget of oxide growth. All these are very attractive for fabricating SiC MOSFETs with high inversion-channel mobility and high hot-carrier reliability.