Representative Critical Reliability Paths for low-cost and accurate on-chip aging evaluation

Aging of transistors degrades circuit performance and can potentially lead to functional failure in the field. This has become a major reliability concern especially when technology further scales to 45 nm and below. It is thus necessary to design on-chip structures that can provide accurate aging evaluation with no performance penalty. In this paper, we propose a novel methodology to accurately evaluate aging in the field. Representative Critical Reliability Paths (RCRP-s) are synthesized as a stand-alone circuit to represent the aging of critical reliability paths, which are defined as paths that can potentially become critical at some point in time due to aging. By monitoring the RCRPs, aging of the critical reliability paths can be efficiently and accurately evaluated with no impact on the normal operation of the chip. The aging evaluation results can then be exploited to guide on-chip performance calibration to ensure lifetime reliability. Simulation results demonstrate the efficiency of the proposed structure.