Improved electrical characteristics of 4H-SiC (0001) MOS devices with atomic layer deposited SiO₂ gate dielectric with H₂O plasma

SiC MOS devices with SiO 2 gate dielectrics deposited by an atomic layer deposition (ALD) process with remote H 2 O plasma were investigated. H 2 O plasma was found to have a strong oxidizing effect compared to that of remote O 2 plasma. Hydroxyl groups found in the SiO 2 films with H 2 O plasma were removed by post-deposition annealing (PDA), and no difference in the IR absorption spectra was found between H 2 O and O 2 plasma samples. A low leakage current and a high breakdown field of 10.5 MV cm −1 were obtained, comparable to the SiO 2 films formed by O 2 plasma. SiC capacitors showed reduced hysteresis of 0.07 V and a better bias stress resistance than an O 2 -plasma-formed SiO 2 film. Moreover, MOSFETs revealed a high peak mobility of 26 cm 2 V −1 s −1 . We postulate that removing hydroxyl groups during the PDA can effectively remove the near-interface defects of SiO 2 /SiC.