Study of SiO2/4H-SiC interface nitridation by post-oxidation annealing in pure nitrogen gas

An alternative and effective method to perform interface nitridation for 4H-SiC metal-oxide-semiconductor (MOS) devices was developed. We found that the high-temperature post-oxidation annealing (POA) in N2 ambient was beneficial to incorporate a sufficient amount of nitrogen atoms directly into thermal SiO2/SiC interfaces. Although N2-POA was ineffective for samples with thick thermal oxide layers, interface nitridation using N2-POA was achieved under certain conditions, i.e., thin SiO2 layers (< 15 nm) and high annealing temperatures (>1350°C). Electrical characterizations of SiC-MOS capacitors treated with high-temperature N2-POA revealed the same evidence of slow trap passivation and fast trap generation that occurred in NO-treated devices fabricated with the optimized nitridation conditions.