The effects of sequential annealing in NO and wet-O2 on interfacial properties and reliability of 4H-SiC (0001) MOS devices

Abstract Post-oxidation annealing (POA) is widely employed in academic research as well as in mass production to improve the properties of SiC MOS devices. We investigate the effect of sequential annealing in NO and wet-O 2 on the interfacial properties and reliability of 4H-SiC MOS capacitors. Compared with SiC MOS capacitors with normal NO annealing, the samples with NO and wet annealing show almost identical interface state density, near-interface trap density and F–N effective barrier height. Regarding the breakdown characteristics, the charge-to-breakdown ( Q BD ) of sample NO/wet is increased by two times compared to sample NO at cumulative failure probability F = 63.2%. Moreover, XPS analysis results confirm that sequential annealing can reduce the interface states and improve the oxide reliability by eliminating Si-related SiO x C y defects and carbon-related defects. The subsequent wet annealing can not only annihilate oxygen vacancies which are generated by additional oxidation after NO POA but also suppress the deterioration of bulk SiO 2 quality to further improve the gate oxide reliability of SiC MOS structures. These results will be useful for improved control of interface state passivation technologies and for further optimization of the properties of the SiO 2 /4H-SiC interface.