Charge trapping/detrapping and dielectric breakdown in SiO/sub 2//Si/sub 3/N/sub 4//SiO/sub 2/ stacked layers on rugged poly-Si under dynamic stress

The authors report a study on charge trapping/detrapping and dielectric breakdown of ultrathin reoxidized Si/sub 3/N/sub 4/ stacked layers on rugged poly-Si under dynamic stress. It was found that the dielectric time-to-breakdown (t/sub BD/) in capacitors with rugged poly-Si under dynamic stress increases with increasing frequency, whereas t/sub BD/ in capacitors with smooth poly-Si decreases with frequency. Charge trapping/detrapping has been studied by monitoring the current-voltage characteristic before and after stress. Results show that for capacitors with rugged poly-Si, hole trapping dominates during electron injection from the top electrode, whereas electron trapping dominates during injection from the bottom electrode. Hole trapping dominates for both polarity injections in capacitors with smooth poly-Si. A dynamic stress-induced breakdown model based on charge trapping/detrapping is proposed.<>