Aging-resilient SRAM design: an end-to-end framework

The performance of transistors degrades due to aging. Bias temperature instability (BTI) is the most prominent aging mechanism in nano-scale CMOS technologies. Aging degradation causes lifetime failures and lowers the quality of shipped chips. We have developed an end-to-end SRAM design framework to maximize the aging resilience under the given constraints. Specifically, we analyze the impact of aging in SRAM peripheral circuits, including address decoder, precharge, write circuit and sense amplifiers (SAs). We explore the efficiency of error-correcting codes (ECC) to combat aging by quantifying the area and delay overheads of ECC and estimating the lifetime yield and DPPM of SRAMs with ECC, respectively. We also calculate the soft error resilience when ECC is used to repair aging failures. After comparing approaches based on cell sizing and ECC in terms of overheads, lifetime yield and DPPM, we can choose either one or a combination of these approaches to identify the optimal design against aging under the given constraints. We integrate our methods into an existing SRAM compiler, CACTI [1], to provide the end-to-end capability to designers.