Piezoelectric ALN MEMS resonators with high coupling coefficient

Piezoelectric AlN resonators with novel checker-patterned electrode architecture are reported in this paper. An array of interdigitated electrodes is used to excite two-dimensional plate acoustic waves within a thin piezoelectric layer. The resonant frequency can be changed by adjusting the size of the electrode fingers and hence resonators with multiple frequencies can be fabricated on a single wafer. A high coupling coefficient of 3.95% has been measured for one of the checker-mode resonators. A comparison of measured S21 plots of a checker-mode resonator and a contour-mode resonator with similar resonant frequency shows that checker mode is highly specific over a large frequency range.