Improvement of SiO2/4H-SiC Interface Using High-Temperature Hydrogen Annealing at Low Pressure and Vacuum Annealing

Abstract

The influences of high-temperature H2 annealing at low pressure (8.5×102 Pa at 1273 K) and vacuum (1× 10-4 Pa at 1273 K) annealing on capacitance-voltage (C-V) characteristics of 4H-SiC MOS structures have been investigated. H2 annealing more effectively reduced the flat band voltage shift of the 4H-SiC MOS structure than vacuum annealing. The interface state density of the 4H-SiC MOS structure after H2 annealing at 1273 K was reduced to approximately one-fifth that of the sample without H2 annealing. Secondary ion mass spectroscopy (SIMS) revealed that hydrogen accumulated at the SiO2/4H-SiC interface, and its density increased with H2 annealing temperature.