Air Damping of Oscillating MEMS Structures: Modeling and Comparison with Experiment

S. Gorelick[1], M. Leivo[1], U. Kantojärvi[1]
[1]VTT Technical Research Centre of Finland, Espoo, Finland

Excessive air damping can be detrimental to the performance of oscillating MEMS components. Complex systems, such as structures in pre-etched cavities or angular comb-drive scanning mirrors, typically require simulations to reliably evaluate the air damping. The simulated and experimental performance of the following systems was evaluated and compared: two types of out-of-plane cantilevers, in-plane and out-of-plane tuning forks, and a torsional mirror. A simplified 2D model of the damping per unit length of the structures and as a function of initial displacement was developed. Experimentally measured Q-values of selected systems were compared with simulated results with 2-30% agreement validating the applicability of the simplified 2D model.