TheEffect oftheSubthreshold SlopeDegradation on NBTI DeviceCharacterization

ForPMOSFETdevices NBTIisa serious reliability concern. Becauseofrecovery effects careful stress and measurement methods mustbeusedtodetermine threshold voltage degradation. These methods assume that mobility and subthreshold slope degradation areminimal. Recent papers havepointed outthat this assumption maynotbevalid. This paper discusses forthefirst timeaunique fast switching NBTI measurement technique thatalternates between twoVGS measurement conditions todetermine thesubthreshold slope vs.stress time.Fromthese measurements theeffect of subthreshold slope degradation onVT degradation canbe accurately determined andresults compared tothestandard techniques. In,addition, thisworkalsointroduces an improved NBTI fastswitching testmethodology to complement thepending NBTIJEDECtesting standard.