Contour-Mode AlN Resonator with High Coupling Factor

Abstract

A micro electro mechanical systems (MEMS) type contour-mode resonator with a high coupling factor of several percent is proposed. The fabricated 60-MHz-band radial-extensional resonators using MEMS process technology of AlN film exhibited a high coupling factor of 2.8% and high Q values of 3000 at the series resonant frequency and 4000 at the parallel resonant frequency. We demonstrated a Pierce type oscillator using the radial-extensional resonators and achieved low power consumption and stable oscillation. These radial-extensional resonators were suitable for filter and oscillator applications because the figure of merit, defined as the ratio of the Q value and the capacitance ratio, was 71 at the series resonant frequency and 94 at the parallel resonant frequency, which were the highest values of the contour-mode AlN resonators.