High Vacuum Circumferentially Distributed Quad Mass MEMS Gyroscope Based on All-Silicon Process

Conservation of momentum and environmental robustness are achieved for the quad mass MEMS gyroscope in both the driving mode and the sense mode. A new type of all-silicon circumferentially distributed quad mass MEMS gyroscope is proposed, and the performance test is completed through the technology process. The four proof masses are distributed surround the central coupling ring symmetrical. Each proof mass has the same amplitude and oppositely phase with neighboring one. The angle rate could be measured by the sense comb difference capacitive signal. Moving structures of the gyroscope are fabricated by deep reactive ion etching, and then vacuum encapsulated by silicon-silicon fusion bonding at wafer level. Internal signals of the gyroscope are lead out through TSVs that fabricated by deep reactive ion etching and wet etching. A wafer-level test system is built, and a phase-locked amplifier was used to test the gyroscope Q value. The Q value can reach more than 300,000, the gyro's bias repeatability at room temperature is 4.44°/h, and the bias instability is 0.69°/h.