Tunable MEMS capacitors considering deformation factor

For electrostatically actuated parallel-plate tunable Microelectromechanical System (MEMS) capacitors in traditional theory, pull-in occurs when the deflection of the movable plate is one-third of the original air gap. In this paper, we fabricated the parallel-plate tunable MEMS capacitors and used WYKO NT1100 optical surface profiler to measure the displacement related with deformation. The results show that only the center of the movable plate nearly fully reached their maximum displacement when pull-in effect occurs, that is, the electrostatic force is nonlinear. The theoretical deviations of the capacitance and pull-in voltage in traditional theory and in this work are more than 2.6% and 1.3%.