Hot-carrier-induced degradation in reoxidized-nitrided-oxide n-MOSFET's under mixed AC-DC stressing

Abstract

Reduced degradation rate can be observed for reoxidized-nitrided-oxide (RNO) n-MOSFETs under dynamic stressing versus the corresponding static stressing. A new degradation mechanism is proposed in which trapped holes in gate oxide are neutralized by the hot-electron injection, with no significant generation of interface states because of the hardening on Si/SiO2 interface by nitridation/reoxidation steps. The RNO device degradation during AC stressing arises mainly from the charge trapping in gate oxide rather than the generation of interface states. Moreover, the AC-stressed RNO devices are significantly inferior to the fresh RNO devices in terms of DC stressing, possibly due to lots of neutral electron traps in gate oxide resulting from the AC stressing.