High quality and high performance gate dielectrics prepared by NH3 nitridation, with equivalent oxide thickness (EOT) down to 1.3-1.6 rim, were firstly investigated. NH3 nitridation can effectively reduces the EOT to a lower down gate leakage current for more than one order in comparison to the control oxide with identical EOT. More significant barrier height lowering in valence band than in conduction band leads to inferior gate leakage behavior in PMOS after NH3 nitridation. In addition, NH3 nitrided NMOS shows a significant improvement in current drivability. But, larger V-lb shift and drivability degradation were observed in PMOS. Fortunately, the most of them can be reduced with post-deposition annealing to meet the process target. The quality and reliability were also exanimated by the hysteresis, temperature and time-to-breakdown characteristics. (C) 2002 Elsevier Science Ltd. All rights reserved.