Apodization techniques for spurious mode suppression in 900 MHz aluminum nitride contour-mode resonators

Abstract

This paper reports, for the first time, on the application of apodization techniques to 900 MHz MEMS AlN Contour-Mode Resonators (CMRs [1]) to efficiently suppress spurious modes in close proximity of the main mechanical resonance. This concept has been applied with excellent results to a variety of one port resonators formed by patterned top electrodes made out of Aluminum, and a floating bottom electrode made out of Platinum sandwiching the AlN film. As also predicted by 3D COMSOL simulations, a complete elimination of spurious responses in the admittance plot of these resonators is attained without impacting their Q or electromechanical coupling coefficient, kt2.