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

Abstract

SiC MOS devices with SiO2 gate dielectrics deposited by an atomic layer deposition (ALD) process with remote H2O plasma were investigated. H2O plasma was found to have a strong oxidizing effect compared to that of remote O2 plasma. Hydroxyl groups found in the SiO2 films with H2O plasma were removed by post-deposition annealing (PDA), and no difference in the IR absorption spectra was found between H2O and O2 plasma samples. A low leakage current and a high breakdown field of 10.5 MV cm−1 were obtained, comparable to the SiO2 films formed by O2 plasma. SiC capacitors showed reduced hysteresis of 0.07 V and a better bias stress resistance than an O2-plasma-formed SiO2 film. Moreover, MOSFETs revealed a high peak mobility of 26 cm2V−1s−1. We postulate that removing hydroxyl groups during the PDA can effectively remove the near-interface defects of SiO2/SiC.