Statistical leakage modeling for accurate yield analysis the CDF matching method and its alternatives

We study the impact of statistical leakage modeling on the yield of memory designs. We critically evaluate different closed form models from a rare fail event perspective and propose CDF matching as a comprehensive and effective approach for accurate statistical leakage modeling. While Schwartz-Yeh method is found to match the body and left tail of the distribution, the Fenton-Wilkinson method aims more at matching the right tail of the distribution. The latter is more critical for purposes of yield estimation in the presence of leaky bitlines devices, as the right tail region is more crucial. However, for practical applications, it is shown that even Fenton-Wilkinson method leads to reduced accuracy compared to the CDF matching method. The error in estimating the probability of a false-read is shown to range from 10x–147x and is expected to increase with technology scaling.