Mechanisms for hot-carrier-induced degradation inreoxidized-nitrided-oxide n-MOSFET's under combined AC/DC stressing

Hot-carrier-induced degradation behavior of reoxidized-nitrided-oxide (RNO) n-MOSFETs under combined AC/DC stressing was extensively studied and compared with conventional-oxide (OX) MOSFETs. A degradation mechanism is proposed in which trapped holes in stressed gate oxide are neutralized by an ensuing hot-electron injection, leaving lots of neutral electron traps in the gate oxide, with no significant generation of interface states. The degradation behavior of threshold voltage, subthreshold gate-voltage swing, and charge-pumping current during a series of AC/DC stressing supports this proposed mechanism. RNO device degradation during AC stressing arises mainly from the charge trapping in gate oxide rather than the generation of interface states due to the hardening of the Si-SiO₂ interface by nitridation/reoxidation steps