Defocus-aware leakage estimation and control

Leakage power is one of the most critical issues for ultra-deep sub-micron technology. Subthreshold leakage depends exponentially on linewidth, and consequently variation in linewidth translates to a large leakage variation. A significant fraction of variation in linewidth occurs due to systematic variations involving focus and pitch. In this paper we propose a new leakage estimation methodology that accounts for focus-dependent variation in linewidth. The ideas presented in this paper significantly improve leakage estimation and can be used in existing leakage reduction techniques to improve their efficacy. We modify the previously proposed gate length biasing technique of [P. Gupta, A. B. Kahng, P. Sharma and D. Sylvester (2004)] to consider systematic variations in linewidth and further reduce leakage power. Our method reduces the leakage spread between worst and best process corners by up to 62%. Defocus awareness improves leakage reduction from gate length biasing by up to 7%.