FinFET-Based Flex-Vth SRAM Design for Drastic Standby-Leakage-Current Reduction

Aiming at drastically reducing standby leakage current, an SRAM using Four-Terminal- (4T-) FinFETs, named Flex-Vth SRAM, with a dynamic row-by-row threshold voltage control (RRTC) was developed. The Flex-Vth SRAM realizes an extremely low standby-leakage current thanks to the flexible threshold-voltage (Vth) controllability of the 4T-FinFETs, while its access speed and static noise margin (SNM) are maintained. A TCAD-based Monte Carlo simulation indicates that even when the process-induced random variation in the device performance is taken into account, the Flex-Vth SRAM reduces the leakage current to 1/100 of that of a standard SRAM in a 256×256 array, where 20-nm-gate-length technologies with the same on-current are assumed.