Voltage-tunable Piezoelectrically-transduced Single-crystal Silicon Resonators on Soi Substrate

This paper reports on a new class of high-Q single crystal silicon (SCS) resonators that are piezoelectrically actuated and sensed, and have voltage-tunable center frequencies. The resonating element is made out of the SCS device layer of a SOI wafer. In a unique manner, piezoelectric transduction was integrated with capacitive fine-tuning of the resonator center frequencies to compensate for any process variations. A quality factor of 6,200 was measured for the 1.7MHz 1 resonance mode of a clamped-clamped beam resonator in 50mTorr vacuum. A 200μm long, 4.2μm thick beam was operated in its higher order modes and demonstrated a Q of 5,300, 3,000, and 2,400 in its 3 (3.3MHz), 4 (4.9MHz), and 5 (6.7MHz) flexural modes, respectively. A 6kHz tuning range was measured for a 719kHz resonator by applying a DC voltage in the range of 0-20V.