SINUSOIDAL AC STRESSING OF THIN-GATE OXIDES AND OXIDE SILICON INTERFACES IN 0.5-MU-M N-MOSFETS/

Sinusoidal ac signals are applied to 90-Angstrom thick gate-oxide in 0 .5-mu m n-MOSFET's. The objective is to emulate ac stressing to device s, recently reported to occur during plasma processes. AC stressing is found to be more damaging to the oxide and oxide/silicon interface wh en compared to de stressing. The damage induced by the ac stress is ob served to depend on the signals frequency and amplitude, It is propose d that carrier hopping is primarily responsible for oxide current and device damage observed following the ac stress, This hopping current i s insignificant during high-field de stress when Fowler-Nordheim tunne ling becomes the dominant conduction mechanism.