An electrostatic quality factor control for surface-micromachined lateral resonators

We present and apply a quality factor control method for laterally driven micromechanical resonant microstructures. The present method modifies the thickness of air-damping gap by applying an electrostatic force between the planar resonant microstructure and ground plane; thereby adjusting the quality factor of the microresonators after fabrication. Polysilicon resonators have been designed and fabricated by a 4-mask surface-micromachining process. The present method reduces the quality factor of the fabricated resonator at the rate of 120/V by applying the electrostatic voltage in the range of 1.75~2.25 V. The maximum 50% reduction of the quality factor has been achieved at the electrostatic voltage of 2.25 V