Hot-carrier effects under AC(Alternating Current)stress are investigated in this paper.Alternative hot-hole and hot-electron injection effects on the degradation of NMOSFET's under pulse stress are discussed mainly.Enhanced degradation appears in both threshold voltage and transconductance under pulse stress.NMOSFET's after hot-hole injection followed by hot-electron injection produce serious degradation

which can be explained by neutral-electron-trap model and hot-carrier-induced gate oxide degradation under pulse stress.The pulsed delay time and pulse frequency effects on NMOSFET's degradation are investigated and analyzed quantitatively

and a detailed explanation is also given out.Under pulse stress

the hot-carrier-induced device degradation is caused by the cooperation of hot holes at low voltage and hot electrons at high voltage.