Improvement in hot carrier lifetime as a function of N sub(2) ion implantation before gate oxide growth in deep submicron NMOS devices

A detailed study of the impact of N sub(2) ion implantation (I/I) dose before gate oxide growth to hot carrier (HC) reliability of NMOSFET's is reported here. Improvements of more than 20xin HC lifetime were achieved by the introduction of sufficiently high N sub(2) (I/I) doses. It was found that for NMOSFET's, the HC degradation correlates inversely to the initial interface state density introduced by the N sub(2) I/I process. This process-driven HC lifetime improvement does not require extensive post-metal anneals for HC lifetime improvements in advanced CMOS multilevel metal-dielectric processes.