Method for manufacturing silicon carbide (sic) semiconductor device by introducing nitrogen concentration of 5x1019 cm-3 or more at a boundary surface between thermal oxide film and the sic substrate and then removing the thermal oxide film

Abstract

A method for manufacturing a semiconductor device includes forming a thermal oxide film on one surface of an SiC substrate by thermal oxidation at a temperature of 1150° C. or above in a gas atmosphere including nitrogen and oxygen, and introducing highly-concentrated nitrogen to one surface of the SiC substrate while forming the thermal oxide film; forming a highly-concentrated n-type SiC layer on one surface of the SiC substrate such that the thermal oxide film is removed from one surface of the SiC substrate by etching and, thereafter, one surface of the SiC substrate is exposed to radicals so that Si—N bonded bodies and C—N bonded bodies on one surface of the SiC substrate are removed while leaving nitrogen introduced into a lattice of SiC out of highly-concentrated nitrogen introduced into one surface of the SiC substrate; and forming an ohmic electrode layer on one surface of the SiC substrate.