Dynamic-stress-induced dielectric breakdown in ultrathin nitride/oxide stacked films deposited on rugged polysilicon

The dielectric breakdown characteristics of thin reoxidized Si/sub 3/N/sub 4/ films on both smooth and rugged poly-Si have been studied under dynamic stressing (unipolar and bipolar) with frequencies of up to 500 kHz. For capacitors with smooth poly-Si the time to breakdown (t/sub BD/) increases with frequency under unipolar stressing with positive gain bias, whereas it slightly decreases with frequency under unipolar and bipolar stressing with negative gate bias. For capacitors with rugged poly-Si, t/sub BD/ increases with frequency in all cases.<
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