Ultrathin stacked Si3N4/SiO2 gate dielectrics prepared by rapid thermal processing

Ultrathin (58 AA equivalent oxide thickness) stacked Si₃N₄/SiO₂ (NO) films with the bottom oxide prepared by rapid thermal oxidation (RTO) in O₂ and the top nitride deposited by rapid thermal processing chemical vapour deposition (RP-CVD) were fabricated and studied. Results show that the charge trapping and leakage current of the stacked films are comparable to those of pure SiO₂ and low-field breakdown events are significantly reduced. By scaling down the top nitride thickness the commonly observed flat-band voltage instability of MNOS devices was minimised, but the low-defect property was still preserved.