Piezoelectric micromechanical disk resonators towards UHF band

This paper presents the design, simulation, fabrication, and test results of a new type of piezoelectrically transduced micromechanical disk resonator approaching UHF frequencies. The resonators were fabricated from silicon-on-insulator (SOI) wafers with a 4-mask low-temperature process. The highest processing temperature was 250°C, allowing post-CMOS integration compatibility. Several prototype resonators with measured diameter of 100 μm and 60 μm were tested in air, with the highest resonant peak observed at 208 MHz, which matched well with simulation results from finite-element analysis. A quality factor of 15 at 208 MHz was extracted, and is expected to be significantly higher with an optimized design and vacuum testing.