Capacitive silicon resonator structure with movable electrodes to reduce capacitive gap widths based on electrostatic parallel plate actuation

This paper presents the design and fabrication of a capacitive silicon resonator with movable electrodes to obtain smaller capacitive gap widths, which results in smaller motional resistance and lower insertion loss. It also helps to increase the tuning frequency range for the compensation of temperature drift of the silicon resonator. The resonant frequency of the fabricated device with a length of 500 μm, width of 440 μm and thickness of 5 μm is observed at 9.65 MHz, and the quality factor is 49,000. Using electrostatically-drived movable electrode structure, it is shown that the motional resistance is reduced by 200 times, the output signal (insertion loss) is improved by 21 dB and the tuning characteristic of the frequency is 7 times larger than those of the structures without movable electrode structures.