Microelectromechanical HF resonators fabricated using a novel SOI-based low-temperature process

This paper reports on a novel silicon-on-insulator (SOI) based low-temperature fabrication process to realize microelectromechanical high-frequency resonators. Key features of the devices are single-crystal silicon resonant beams, 400-nm or 600-nm thin transducer gaps, and gold electrodes. The fabrication process combines bulk silicon micromachining applying deep reactive ion etching, low-temperature deposition of a thin sacrificial oxide layer, and electroplating of the lateral electrodes. The resonant behavior of devices with resonance frequencies f_res between 420 kHz and 4.11 MHz was characterized as a function of the bias voltage V_bias applied to the beam. Measurements were performed at ambient pressures p between 5×10^-3 Pa and 0.5 Pa. Q values up to 52000 at f_res=420 kHz and 6000 at f_res=4.11 MHz were obtained. The interaction of resonator and measurement setup were simulated using an electrical network simulation program combined with a finite element analysis using ANSYS.