Effects of localized interface defects caused by hot-carrier stress in n-channel MOSFETs at low temperature

摘要

Hot-carrier stressing was carried out on 1- mu m n-type MOSFETs at 77 K with fixed drain voltage V/sub d/=5.5 V and gate voltage V/sub g/ varying from 1.5 to 6.5 V. It was found that the maximum transconductance degradation Delta G/sub m/ and threshold voltage shift Delta V/sub t/, do not occur at the same V/sub g/. As well, Delta K/sub t/ is very small for the V/sub g/>V/sub d/ stress regime, becomes significant at V/sub g/ approximately=V/sub d/, and then increases rapidly with increasing V/sub g/, whereas Delta G/sub m/ has its maximum maximum in the region of maximum substrate current. The behavior is explained by the localized nature of induced defects, which is also responsible for a distortion of the transconductance curves and even a slight temporary increase in the transconductance during stress.