Transistor reliability variation correlation to threshold voltage

MOSFET reliability data are often represented as a function of gate overdrive (V_G-V_T) with the implicit assumption that overdrive is the appropriate normalizing parameter. While this can be true for some specific sources of variation, reliability does not necessarily track gate overdrive. This paper explores systematic and random sources of variation in TDDB, BTI, and hot carrier degradation data in Intel´s tri-gate technologies. We find that random variation captured within a baseline of reliability data does not, in general, trend with overdrive. However, some sources of systematic variation are correlated or, interestingly, anti-correlated with overdrive.