Design and fabrication of a tuning fork shaped voltage controlled resonator for low-voltage applications with additional tuning electrodes

Abstract

In this work a silicon voltage controlled microelectromechanical tuning fork resonator with electrostatic actuation and separate frequency tuning electrodes is presented. The released device is fabricated using a silicon-on-insulator wafer by a two-step process involving only focused ion beam masking and cryogenic deep reactive ion etching. This process is ideal for rapid prototyping, as the time to turn a design into the final device is only a few hours. The design of the resonator is optimized to accommodate the restrictions of the fabrication process, to maximize the frequency tuning range and to minimize the biasing voltage. Separating tuning and driving electrodes enables the resonance frequency adjustment by over 70 000 ppm (fcenter > 1.5 MHz, quality factor Q ≈ 2000) with a tuning voltage of 29 V in an open loop mode.