Statistical aspects of the degradation of LDD nMOSFETs

Abstract

The spread between hot-carrier degradation curves of LDD nMOSFETs, stressed at thesame level, is studied. It's observed that a large part of this variation can be explained by the difference in initial drain current I-d,I-sat. A relationship between the amount of degradation or equivalently the lifetime and I-d,I-sat is used to predict the degradation behaviour (at this stress level) or the lifetime of a single LDD nMOSFET from its value of I-d,I-sat. By introducing I-d/sat into the statistical analysis, the variance of the failure time distribution is reduced and a failure time distribution can be estimated at specific values of I-d,I-sat. The parameter I-d,I-sat can be used to select the more reliable LDD nMOSFETs out of a population. (C) 2002 Elsevier Science Ltd. All rights reserved.