Design, Analysis, and System-Level Simulation of a Micromachined Resonant Charge Sensor with Microleverage Mechanisms

摘要

In this paper, a micromechanical electrostatic resonant charge sensor with responsivity enhanced by introducing dual single-stage microleverage mechanisms (microlevers) is presented. The sensor is based on the mechanism of detecting the resonant frequency shift of a single-crystal silicon double-ended tuning fork (DETF) element due to the axial compression generated by the additional charge and transformed by the microlevers. An analytic model comprising both mechanical and electrical subsystems was derived. The system-level simulation was carried out to optimize the critical dimensions and responsivity that coincides with the theoretical solution. The resonator has a nominal resonant frequency of 166 kHz and the amplification factor is more than 8. Simulation results suggest that the responsivity of the charge sensor is 1.38 × 10~(-3)Hz/fC~2. Finally, the device was fabricated in a commercial standard silicon-on-insulator (SOI) micromachining process to reduce the parasitic capacitance more effectively by back-side release.