Adhesive Force Characterization for MEM Logic Relays With Sub-Micron Contacting Regions

Contact adhesive force (Fa) scaling is critical for relay miniaturization, since the actuation area and/or actuation voltage must be sufficiently large to overcome the spring restoring force (Fk) in order to turn on the relay and Fk must be larger than Fa in order to turn off the relay. In this work, contact adhesive force is investigated in MEM logic relays with contact dimple regions as small as 100 nm in lateral dimension. The results indicate that van der Waals force is predominant. An adhesive force of 0.02 nN/nm² is extracted for tungsten-to-tungsten contact. Fa reduction should be possible with contact dimple size reduction and contact surface coating.