The gate leakage current and reliability concern become more serious due to the aggressive scaling-down of the gate oxide thickness. In this paper, the gate leakage current reduction and reliability optimization with an EOT 15A plasma nitrided gate oxide were explored. The plasma nitrided oxide fabricated by plasma nitridation process demonstrated good gate leakage reduction and high carrier mobility without sacrificing the reliability performance. The optimization of nitrogen profile and post nitridation annealing has been also discussed. (C) 2004 Elsevier Ltd. All rights reserved.