A Review of Adhesion in an Ohmic Microswitch

Due to fundamental scaling laws, the effect of surface forces becomes relatively large for microscale structures, such as MEMS. The operation of an ohmic MEMS microswitch relies on repeated make-and-break contacts, typically between each of two metal tips and a metal drain. Large contact forces are desirable for low contact resistance, but the resulting plastic deformation at this small scale, as well as the breaking through of contaminant films, further increases the adhesion force which can then exceed the restoring force of the actuator. This stuck-closed failure, also known as stiction, is a major hindrance to switch reliability and to the ultimate commercialization of these devices. In this article we review the experimental and modeling efforts which have been directed to achieving an improved understanding of adhesion in an ohmic MEMS microswitch. (C) Koninklijke Brill NV, Leiden, 2010