The invention discloses a method for manufacturing a low-offset
flat band voltage SiC
MOS capacitor, which mainly solves the problem that the trap intensity of a SiC / SiO2 interface is too high. The method comprises the following manufacturing processes: cleaning an N-SiC
epitaxy material; after injecting N<+> into a SiC
epitaxy layer by
ion injection, injecting Al<-> into the
epitaxy layer; oxidizing a layer of SiO2 on the epitaxy layer after the
ion injection in the mode of dry-
oxygen; sequentially finishing the annealing in Ar gas environment, the wet-
oxygen oxidation annealing in wet-
oxygen environment and the
cold treatment in the Ar gas environment of an oxidized sample
wafer; depositing a layer of SiO2 on the sample
wafer after the
cold treatment by
chemical vapor deposition and first annealing the sample
wafer in the Ar gas environment; and manufacturing an
electrode by vacuum
sputtering of Al and carrying out second annealing in the Ar gas environment so as to finish manufacturing the whole
capacitor. The invention has the advantages of accurate control of N<+>\Al<-> doses, low trap intensity of the SiC / SiO2 interface, small
flat band voltage offset of the SiC
MOS capacitor and simple achieving process and can be used for improving the characteristics of the SiC / SiO2 interface of an N type SiC MOS device.