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

Abstract

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.