Bimodal lifetime distributions of dielectrics for integrated circuits

Constant voltage stressing of large area capacitors with thin thermal oxide and ONO dielectrics reveals that defect related breakdown is the dominant failure mode. Elimination of the complete early failure mode by means of screening will neither be possible nor necessary. Consequently, prediction of failure rates under operating conditions must be deduced from defect‐related distributions. A statistical model is introduced and discussed in order to extrapolate to small failure percentages. Furthermore an additional term is introduced in the effective thickness model of Lee et al. which takes into account the weaker field acceleration behaviour of very thin dielectrics.