Stability of microelectromechanical devices for electrical metrology

Microelectromechanical systems (MEMS) have been recently proposed for realizing several references in electrical metrology. Such devices are formed from micromachined electrodes of which at least one is supported by a compliant structure such that an electrostatic force between two electrodes displaces the moving electrode. The properties of these electromechanical devices can be very stable if they are fabricated from single-crystalline silicon and sealed hermetically in a low-pressure atmosphere. In comparison to several semiconducting reference devices, micromechanical components are large in size and consume a negligible power. Thus, a low 1/f noise level is expected. The proposed MEMS electrical references include a DC and an AC voltage reference, an AC/DC converter, a low-frequency voltage divider, a microwave and millimeter-wave detector, a DC current reference, etc. Measurements on a prototype for a MEMS DC reference are discussed. The stability is presently limited by charge fluctuations on the native oxides of electrode surfaces. Preliminary results show relative fluctuations below 1 μV/V