RF MEMS Metal-Contact Switches With mN-Contact and Restoring Forces and Low Process Sensitivity

This paper presents an electrostatic RF microelectromechanical systems (MEMS) metal contact switch based on a tethered cantilever topology. The use of tethers results in a design that has low sensitivity to stress gradients, biaxial stresses, and temperature. A switch with a footprint of 160 190 mu m(2) and based on a 8-mu m-thick gold cantilever with an Au/Ru contact is implemented on a high-resistivity silicon substrate and results in a total contact force of 0.8-1.2 mN at 80-90 V, a restoring force of 0.5 mN, a pull-in voltage of 61 V, an up-state capacitance of 24 fF, and an actuation time of 6.4 s. The device achieves a switch resistance of 2.4 +/- 1.4 Omega to 1.8 +/- 0.6 Omega at 90-100 V in open laboratory environments (nonpackaged). This design has the potential to replace conventional electromagnetic relays in application areas such as automated testing equipment and high-performance switching networks.