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 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 infrared absorption spectra was found between H2O and O2 plasma samples. A low leakage current and a high breakdown field of 10.5 MV/cm 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 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.