Multi-Functional CMOS Compatible Nano-Electro-Mechanical Relays for Vapor Phase Explosive Detection

Nano-electro-mechanical (NEM) relays play a very important role in ultra-low standby power and ultra-low power vapor phase gas sensor for Internet-of-Things sensor applications. In this paper, for the first time, we demonstrate a multi-functional fully-CMOS compatible titanium-based NEM relay with 1.8V actuation voltage, ~100Ω R
_ON
, 50ns turn ON delay, and 10
⁹
ON/OFF current ratio in the ambient conditions. The innovative feature of this paper lies on the novel combination of grayscale electron beam lithography and a bi-layer lift-off process at room temperature (RT) to realize an NEM relay. This novel combination facilitates easy release of structures with an air gap of 25nm and a beam size of 1μm × 1.5μm. As an example, using the proposed self-purging NEM relay, a vapor phase gas sensing application is successfully demonstrated for explosives detection in an ambient air at RT.