New methodology for modelling MOL TDDB coping with variability

We report a novel time-dependent dielectric breakdown (TDDB) lifetime model which accounts for the impact of various sources of variability. We prove that the standard Weibull and Lognormal distributions normally used for FEOL and BEOL TDDB lifetime predictions respectively are not adequate for MOL TDDB analysis. Due to the many sources of variability, only a combination of different variability separation techniques — even including a convolution of a Weibull and Lognormal distribution as a last resort for some cases — can reconcile the intrinsic breakdown mechanism with the extra variability. This approach is shown to correctly fit and predict the reliability of integrated low-k spacer dielectrics.