Investigation of thermally grown oxide on 4H-SiC by a combination of H2O and HNO3 vapor with varied HNO3 solution heating temperature

A new technique of oxidizing n-type 4H-SiC in a combination of H2O and nitric acid (HNO3) vapor at various heating temperatures (60 °C, 70 °C, 80 °C, 90 °C, 100 °C and 110 °C) of HNO3 solution has been introduced in this work. Utilizing secondary ion mass spectroscopy, effects of H+ and N− on the passivation of structural defects at the bulk oxide and partial of the SiC/SiO2 interface have been discussed. The effects of heating temperature of HNO3 solution on structural properties of the SiC substrate; after the oxide has been removed have been systematically investigated. Contact angles and the surface roughness of the substrate were recorded from a Goniometer and an atomic force microscope, respectively. It has been revealed that as compared to oxide grown by conventional wet (H2O vapor only) oxidation technique; this “wet diluted nitridation” technique is able to produce oxide with lower interface-state density and higher breakdown voltage. Physical properties of the substrate after oxide removal show surface roughness reduces as the heating temperature of HNO3 solution increases, which is mainly attributed by the significant reduction of carbon content at the SiC/SiO2 interface.