Sinusoidal AC stressing of thin-gate oxides and oxide/silicon interfaces in 0.5-μm n-MOSFETs

Sinusoidal ac signals are applied to 90-/spl Aring/ thick gate-oxide in 0.5-μm n-MOSFETs. The objective is to emulate ac stressing to devices, recently reported to occur during plasma processes. AC stressing is found to be more damaging to the oxide and oxide/silicon interface when compared to dc stressing. The damage induced by the ac stress is observed to depend on the signals frequency and amplitude. It is proposed that carrier hopping is primarily responsible for oxide current and device damage observed following the ac stress. This hopping current is insignificant during high-field dc stress when Fowler-Nordheim tunneling becomes the dominant conduction mechanism.