Fabrication and characterization of an SOI MEMS gyroscope

This paper presents an SOI (silicon on insulator) MEMS (micro-electro-mechanical systems) vibratory gyroscope that was fabricated using bulk micromachining processes. In the gyroscope architecture, a frame structure that nests the proof mass is used to decouple the drive motion and sense motion. This approach ensures that the drive motion is well aligned with the designed drive axis, and minimizes the actual drive motion component along the sense detection axis. The thickness of the structural layer of the device is 100 μm, which induces a high elastic stiffness in the thickness direction, so it can suppress the high-order out-of-plane resonant modes to reduce deviation. In addition, the dynamics of the gyroscope indicate that higher driving mass brings about higher sensing displacements. The thick structural layer can improve the output of the device by offering a sufficient mass weight and large sensing capacitance. The preliminary test results of the vacuum packaged device under atmospheric pressure will be provided. The scale factor is 1.316 × 10−4 V/(deg/s), the scale factor nonlinearity and asymmetry are 1.87% and 0.36%, the zero-rate offset is 7.74 × 10−4 V, and the zero-rate stability is 404 deg/h, respectively.