Design and Fabrication of Quartz Micro-Electro-Mechanical System-Based Double-Ended Tuning Fork with Variable Sections

In this paper, we report a novel double-ended tuning fork (DETF) with variable sections. The DETF is fabricated using a quartz micro-electro-mechanical system (MEMS) technique and packaged using the flip chip technique. The central part of the vibration beam is thinned to enhance the force-frequency sensitivity but not decrease the vibration frequency. The mechanical quality factor ( Q value) can also be maintained, which determines the mechanical noise performance. Three types of DETF are designed and fabricated with a fixed beam length of 4 mm. The vibration characteristics (vibration frequency, Q value, and equivalent circuit parameters) are evaluated using an impedance analyzer 4294A. The finite element method (FEM) is used to simulate the natural frequency and force-frequency sensitivity. For the natural frequencies, the experimental results agreed well with the simulation results. High Q values are achieved for all the DETFs, which are 9924, 7083, and 6335. By multiplying the force-frequency sensitivity (Δ F ) by the measured Q values, the performance of the new DETF structure can be improved by 1.9 times.