On Characterizing Near-Threshold SRAM Failures in FinFET Technology

Adoption of near-threshold voltage (NTV) operation in SRAM-based memories has been limited by reduced robustness resulting from marginal transistor operation that results in bit failures. Using silicon measurements from a large sample of 14nm FinFET test chips, we show that our cells operate at frequencies of up to 1GHz with a minimum 15% voltage guardband, below which the cells begin to fail. We find that when operated at 32.5% below nominal voltage, >95% of the lines experience fewer than 2 failures, which can be corrected with SECDED ECC. Our results indicate that for frequencies of up to 1GHz, NTV can help maximize power savings potential while requiring minimal protection.