Impact of nMOS/pMOS gate length correlation on the accuracy of statistical modeling

In LSI design of modern scaled-down technologies, the statistical model is used to take process variation effects into account. In order to predict device fluctuations in early stages of device development, the TCAD approach of statistical modeling has already been introduced in some reports. But from statistical modelling points of view, prediction accuracy of such TCAD approaches has not been sufficiently discussed. In this paper, statistical distribution of factory-manufactured devices is compared carefully to the prediction of TCAD. It is revealed that there is no serious accuracy problem in statistical model prediction even with economically calibrated TCAD, On the other hand, consideration of nMOS and pMOS gate length correlation is found to be critical to the prediction