Contact Resistance Measurements and Modeling of an Electrostatically Actuated Microswitch

Micromechanical switches have been fabricated in electroplated nickel using a four-level surface micromachining process. The simplest devices are configured with three terminals, a source, a drain, and a gate and are 30 µm wide, 1 µm thick, and 65 µm long. A voltage applied between the gate and the source closes the switch, connecting the source to the drain. Devices operate for more than 109 cycles in a nitrogen ambient before failure and have an initial contact resistance of less than 50 mΩ. The threshold voltages for these devices are between 30 V and 200 V. Long lifetimes are achieved with a current of 30 mA. The breakdown (stand-off) voltage between the source and the drain is greater than 100 V and the off-impedance exceeds 1012Ω. The modeling of these switches includes a structural model of the beam and a contact resistance model for the electrical contact. Preliminary contact resistance measurements are presented and compared with the modeled contact resistance characteristics.