Development of a new technological MEMS process for AC voltage standards

Abstract

This paper describes the development of a new technological process for manufacturing MEMS with out-of-plane motion in order to develop voltage references with high stability (deviation from the nominal value less than some 10 -6 per year) and working in alternating current (AC). In this application, the AC voltage reference is defined at the pull-in point of the MEMS variable capacitor made of two electrodes, one fixed and the other movable driven by an AC current having a frequency much higher than the mechanical resonant frequency. This process has been developed to get MEMS devices exhibiting high nominal capacitances, which makes the development of the read-out electronics easier, and metallized electrodes to avoid charge effects on the stability of the voltage standard. Moreover, this process allows to realize stoppers, in order to get a good operational reliability.