EFFECT OF CURVATURE AND ELECTRODE COVERAGE ON THE QUALITY FACTOR OF BICONVEX ALN-ON-SI MEMS RESONATORS

This paper analyzes for the first time the effect of incrementally varying the curvature of a MEMS contour mode resonator on its quality factor (Q). The change in curvature is analyzed in terms of the change in width of the acoustic cavity. Our experimental results show that the change in width of the acoustic cavity should be at least half the acoustic wavelength (lambda) of the resonant cavity to achieve optimal and consistent improvement in Q. However, curving beyond lambda drastically reduces coupling while providing little improvement in Q. We also examine the impact of electrode coverage for Q-enhanced biconvex resonators: Narrowing the width of the electrodes tends to increase Q but shortening the length reduces Q slightly.