ACES characterization of damping in micro-beam resonators

摘要

This study develops a preliminary model ofQ-factor of MEMS resonators by usingAnalytical, Computational, andExperimental Solutions (ACES) methodologyto investigate the effects of variousdamping mechanisms on the Q-factor ofmicroelectromechanical resonators. Focuswas made on the contributions of airdamping, thermoelastic damping (TED), andsurface damping to the Q-factor. LaserDoppler Vibrometry (LDV) and MichelsonInterferometry were used to characterizethe damping of tipless atomic forcemicroscopy (AFM) probes through ringdown tests. Tests were performed atvarious levels of vacuum with differentbeam geometries and coatings. COMSOLwas used to model the TED as well asresonance characteristics of the beams andthe computational results were comparedto analytical and experimental results. Itwas found that as surface area to volumeratio increases beyond approximately1 μm~(-1), surface damping becomes thedominant damping mechanism.Additionally air damping was significant at avacuum level greater than approximately0.1 μbar. It was also found that surfacedamping was much greater with Au-Pd andAl coatings applied. Finally, the dissipationterm in the analytical approximation ofsurface damping was calculated for theabove coatings.