Reliability-Driven Voltage Optimization for NCFET-based SRAM Memory Banks

Negative Capacitance Field-Effect Transistors (NCFET) are promising significant power reductions while maintaining performance due to their internal voltage amplification. However, the addition of the ferroelectric layer also introduces a higher gate capacitance, which has to be charged and discharged resulting in higher power consumption. This results in trade-offs when employing NC-FinFET with respect to the thickness of the ferroelectric layer and their operating voltage on power, performance and reliability in circuits. This design-space is currently not explored, as existing research focused on a transistor-to-transistor comparison to show the superiority of NC-FinFET at the same voltage. In this work, we evaluate NC-FinFET employment in a full SRAM memory array (including write driver, sense amplifier, pre-charging, etc.) to obtain circuit delay, read and hold power and reliability metrics. This work shows, that solely evaluating SRAM cells results in inaccurate delay and power estimations compared to a full SRAM array. We explore iso-voltage and iso-performance NC-FinFET operation. Additionally, we explore two new operation modes: operating NC-FinFET within the same overall power consumption (iso-power) and operating at the same noise margins (iso-reliability). This exploration shows, for the first time, how ferroelectric layer thickness plays a role on reliability as a 4 nm layer features a 47% loss compared to FinFET. Lastly, we obtain the activity of a register file in a processor simulator to obtain the ultimate impact on power and energy consumption of employing NC-FinFET in a microprocessor.