Laterally actuated multicontact MEMS relay fabricated using MetalMUMPS process: experimental characterization and multiscale contact modeling

Abstract

Multicontact MEMS relays laterally actuated using electrostatic comb-drive actuators are reported. The relay consists of a movable main beam anchored to the substrate using two identical folded suspension springs. Multicontact RF ports consist of five movable fingers connected to the movable main beam and six fixed fingers anchored to the substrate. Comb-drive actuators located at the top and bottom ends of the main beam enable bidirectional actuation of the RF contacts. The MEMS relays were fabricated using the MetalMUMPs process, which uses 20-µm-thick electroplated nickel as the structural layer. A 3-µm-thick gold layer was electroplated at the electrical contact surfaces. An example MEMS relay with planar contacts of area 80 µm×20 µm and a spacing of 10 µm between the movable and fixed contacting surfaces is discussed. The overall size of the relay is approximately 3 mm×3 mm. "Resistance versus applied voltage" characteristics of the MEMS relay have been measured for applied DC bias voltages in the range of 172 V to 220 V. A multiscale rough surface contact model was used to estimate the actual electrical contact resistance versus applied force curve of these devices. The multiscale model showed good qualitative agreement with the experimental measurements but requires more refinement to achieve good quantitative agreement.