Hybrid NEMS–CMOS integrated circuits: a novel strategy for energy-efficient designs
Substantial increase in gate and sub-threshold leakage of complementary metal-oxide-semiconductor (CMOS) devices is making it extremely challenging to achieve energy-efficient designs while continuing their scaling at the same pace as in the past few decades. Designers constantly sacrifice higher levels of performance to limit the ever-increasing leakage power consumption. One possible solution to tackle the leakage issue, which is proposed in this work, is to integrate nano-electro-mechanical switches (NEMS) with CMOS technology. Hybrid NEMS–CMOS technology takes advantage of both near-zero-leakage characteristics of NEMS devices along with high ON current of CMOS transistors. The feasibility of integration of NEMS switches into a CMOS process is illustrated by a practical process flow. Moreover, co-design of hybrid NEMS–CMOS as low-power dynamic OR gates, static random access memory (SRAM) cells and sleep transistors is explored. Simulation results indicate that such hybrid dynamic OR gates can achieve 60–80% lower switching power and almost zero-leakage power consumption with minor delay penalty. However, the hybrid OR gate outperforms its CMOS counterpart both in terms of delay and switching power consumption with increase in fan-in beyond 12. Additionally, it is shown that a hybrid NEMS–CMOS SRAM cell can achieve almost 8× lower standby leakage power consumption with only minor noise margin and latency cost. Finally, application of NEMS devices as sleep transistors results in up to three orders of magnitude lower OFF current with negligible performance degradation as compared to CMOS sleep switches.
