Channel width dependence of AC stress on bulk nMOSFETs.

Channel width dependence of AC stress was investigated. OFF-state stress generated negative interface traps, positive oxide charges, and neutral traps in the whole channel region. Comparison of drain currents of parasitic and main MOSFET during OFF-state indicates that more defects were generated on channel edge than near its center. During ON-state stress, electrons were dominantly trapped in the neutral traps near channel edge. These results cause degradation due to AC stress to become increasingly severe as W is scaled down. The operating voltage to guarantee 10-year lifetime decreased as width decreased. The above results show that electron trapping in neutral traps near the channel edge induce severe degradation on narrow nMOSFET during AC stress. Therefore, degradation of channel edge during AC stress is an importantly considered in narrow nMOSFET.