Weibull breakdown characteristics and oxide thickness uniformity

In this work, we investigated both experimentally and numerically the impac t of macroscopic oxide thickness uniformity on Weibull breakdown characteri stics for both Weibull parameters, namely, the characteristic times and Wei bull slopes over a wide range of oxide thicknesses. We report the abnormal characteristics of the Weibull time-to-breakdown distributions and non-Pois son area scaling behavior observed on ultrathin oxides. Two numerical metho ds using the parameters obtained from two independent sets of experimental results are developed to quantitatively explain these effects in the contex t of current modulation due to oxide thickness variation. The relationship between time-to-breakdown and charge-to-breakdown distributions has been cl arified and established. It is found that without proper treatment of these effects, the use of Weibull slopes at higher failure percentiles can lead to erroneous and pessimistic reliability projection. Furthermore, we perfor m a detailed full-scale Monte Carlo analysis to evaluate the impact of thic kness variation on low-percentile breakdown distributions and their sensiti vity to the thickness dependence of the times-to-breakdown and Weibull slop es.