The surface morphology of the polycrystalline and single-crystal SiC treated with pure NF{sub}3 plasma and analysis on chemical reaction of SiC with NF{sub}3

摘要

Silicon carbide (SiC) is a promising semiconductor material for use in high temperature and high power electronic device applications, because of its attractive properties such as a wide band gap (2.3eV) at 300K, a high thermal conductivity (5W/cm°C), etc. In addition, its high breakdown electric field (3.0×10{sup}6V/cm) and high saturated electron drift velocity(2.7×10{sup}7cm/s) make SiC-based devices suitable for high power and high frequency applications. However its poor machinability, which originates from its high mechanical strength and chemical stability, is a serious problem for using these applications. In the semiconductor industry in Japan, a large amount of nitrogen trifluoride (NF{sub}3) is now used as a dry etchant and a cleaner gas for CVD chambers. NF{sub}3 is chosen as a fluorine radical (F·) source, because it efficiently decomposes to from free radicals, and all possible reaction products are volatile, thus avoiding contamination or polymer formation in the chamber. With these scientific backgrounds, etching of SiC in NF{sub}3 plasma has been studied.