Capillarity and electromigration effects on asperity contact evolution in microelectromechanical systems switches

Morphology evolution of asperity contacts in microelectromechanical systems switches is examined in the framework of the phase field method. Surface mass diffusion, driven by capillarity, rapidly increases the asperity contact radius at early times, decreases it slowly at later times, and, possibly, pinches off the contact due to a Rayleigh instability. Electromigration accelerates this process but retards or prevents the pinch off at late times. The evolution occurs faster when the asperity size and/or density are smaller. Approximate analytical results for the evolution kinetics are provided. (c) 2006 American Institute of Physics.