Piezoelectric buckling-based NEMS relays for millivolt mechanical logic

We report on the design, fabrication, characterization, and scaling analysis of buckling-based NEMS 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 the source and drain, while the residual stress 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 (~1.8 V), and uniquely achieves an equivalent electric body bias via mechanical methods. Analytical and FEA simulation show a linear dependence of the switching voltage on the residual stress, while the voltage vs. stress tuning slope is reduced linearly with scaling the piezoelectric film thickness (-16.6 mV/MPa for 10 nm thick AlN film). A scaling analysis shows that millivolt switching is possible for aggressively miniaturized relays.