Electrical Properties Of SiO₂/SiC Interface Treated By Nitrogen And Hydrogen Plasma

SiC has wide application in the field of high temperature, high frequency, high power and radioresistance because of its excellent physics and electronic characteristics, such as wide band gap, high breakdown electrical field and high thermal conductivity. The best property of SiC is it can generate the intrinsic dioxide-SiO₂ through thermal oxidation. This makes it easily fabricate SiC MOS devices according to silicon processes. In fact, the channel mobility of the real SiC MOS devices is very low. One of the main reasons is the high interfacestates density between SiO₂ and SiC. To reduce the interface states density of SiO₂/SiC system has became the most important technology in fabricating SiC MOS devices.In this paper, ECR plasma treatment system was used to treat SiO₂/ SiC interface, and MOS capacitor was fabricated for testing electrical properties. The reliability of the dioxide was analyzed through I-V test and Fowler-Nordheim current model. 9.95MV/cm of breakdownelectrical field was got, and the barrier height between SiO₂ and SiC was 2.71eV which is nearly to the theoretical value of 2.72eV. The plasma treatment effect was revealed through C-V test qualitatively, and -2.23×10¹¹cm^-1 of effective charge density in oxide was got. The interface states density was quantative calculated through high frequency test and Hi-Lo calculation, and the relationship curve between interface states density and energy was also drawed. The interface states density of 1.14×10¹²cm^-2eV^-1 was got near the conduction band edge about the sample of 10min treatment.The results revealed that, nitrogen and hydrogen plasma treatment could improve the SiO₂/ SiC interface properties. The low SiO₂/ SiC interface states density was obtained, meanwhile the dioxide showed great reliabilites. These results play an important role in studying and improving the SiC MOSFET processes.