On the notion of vdW-force loaded hysteretic switching for precise release voltage design in all-metal electrostatic logic relay

Abstract

In electrostatic switches, the inability to correlate hysteretic-switching (an electrical attribute) and adhesion force (a structural attribute) makes the predictive design difficult. The van-der-Waals interactions (FvdW) to adhesion may even be large enough to cause the release voltage (VREL) to shift past V = 0, afterward, the device never spring-back when the gate voltage is removed. The main part of this paper is devoted to addressing this issue in all-metal relay configuration. We present a physical model for shifting of VREL in its switching curve. A rule-based analytical model for VREL (precisely correlating FvdW) is first derived and found to be well fitted with the experimental data. The fabricated all-metal dielectric-less relay design mitigates the nonidealities (e.g. no work-function difference and no dielectric-charging) in FvdW calculation which is a major improvement over the past approach. Our modeling outcomes improve the understanding of how surface effects (mainly vdW force) influence the releasing sequence in M/NEMS devices that often employ contact-based switching. Temperature influence on switching characteristics is also investigated. The results demonstrate that lateral-dimensions and the temperature drive pull-out (PO) operation more dominantly than pull-in (PI).