Weibull breakdown characteristics and oxide thickness uniformity

In this work, we investigated both experimentally and numerically the impact of macroscopic oxide thickness uniformity on Weibull breakdown characteristics for both Weibull parameters, namely, the characteristic times and Weibull slopes over a wide range of oxide thicknesses. We report the abnormal characteristics of the Weibull time-to-breakdown distributions and non-Poisson area scaling behavior observed on ultrathin oxides. Two numerical methods using the parameters obtained from two independent sets of experimental results are developed to quantitatively explain these effects in the context of current modulation due to oxide thickness variation. The relationship between time-to-breakdown and charge-to-breakdown distributions has been clarified 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, me perform a detailed full-scale Monte Carlo analysis to evaluate the impact of thickness variation on low-percentile breakdown distributions and their sensitivity to the thickness dependence of the times-to-breakdown and Weibull slopes.