Highly Scalable NEMS Relays With Stress-Tuned Switching Voltage Using Piezoelectric Buckling Actuators

This paper reports the design, fabrication, characterization, and scaling analysis of novel buckling-based nanoelectromechanical relays that use, for the first time, piezoelectric actuation. The generated stress from anchored piezoelectric films is employed to buckle a clamped-clamped beam to connect suspended source and drain terminals, while the residual stress in the beam is used to control the actuation voltage. This demonstration is the first of its kind to exploit residual stress to deliver a highly scalable switching mechanism that exhibits low actuation voltage (~1.8V), very fast switching (~80 ns), and uniquely achieves an equivalent electric body bias via mechanical methods. Finite-element analysis and analytical simulations show a linear dependence of the switching voltage on the residual stress, while the voltage versus stress tuning slope is reduced linearly with scaling the piezoelectric film thickness (-16.6 mV/MPa for 10-nm thick aluminum nitride film). A scaling analysis shows that millivolt switching is possible for aggressively miniaturized relays, which highlights the great impact this technology could have on demonstrating ultralow power digital circuits and memories.