A high Q micromachined single crystal silicon bulk mode resonator with pre-etched cavity

In this paper, a novel method of fabricating micromachined single crystal silicon bulk mode resonators is demonstrated. The most distinguishing feature of this method is that the resonator structure is fabricated and released simultaneously in the end of the process, as a cavity for structure release is pre-etched in the substrate layer. The advantages of this process include: simplifying the fabrication process by fabricating and releasing the device structure simultaneously; enhancing fabrication yield through eliminating the sacrificial release step needed for existing process. The complete process has been validated and prototypes have been fabricated. The transmission performance of a 4.13 MHz Lamé mode square resonator fabricated using this method is presented, with a quality factor of 8,400 in air and exceeding one million at pressure of 0.11 mbar, respectively.