Research On Design And Fabrication Of Structure-Decoupled Quadruple Mass Mems Gyroscope Based On SOI

The traditional single mass gyroscope is simple in structure and easy to process,but the common-mode interference caused by the external environment limits its overall performance.On this basis,the structure of dual mass can effectively eliminate the common-mode signals generated by the environment due to the method of differential detection.However,because of the asymmetry between two operation modes of dual mass,the frequency split of the gyroscope is large,resulting in the relatively small amplitude of sense mode.Therefore,in this paper,the structure of quadruple mass is studied,which not only keeps high environmental robustness,but also makes the structure have high symmetry.In this paper,structure design and preparation method of a novel structure-decoupled quadruple mass gyroscope are proposed.Design of comb electrode and push-pull method are used to eliminate the second harmonic component of the electrostatic driving force.Through the design of two degrees of freedom,the structure of folding beam is simulated,analyzed and optimized to effectively realize the ideal decoupling effect.According to the structure of the quadruple mass gyroscope,a feasible process plan is designed and the practical processing is carried out.Samples of the quadruple mass gyroscope are finally made by using SOI and anode bonding process,at the same time,the test of structure,decoupling effect and resonance frequency scanning are carried out after non-vacuum packaging.Through the modal analysis,the frequency spit of gyroscope is 7 Hz,which shows the high symmetry of its structure.Under the harmonic response analysis,the maximum displacement difference of the drive frame is 60.75 nm,and the deflection angle of the sense frame around its center is about 0.0357 °,which achieves the ideal decoupling effect.The Q values of thermo elastic damping of drive and sense modes are 64156.68 and 64105.25 respectively.The drive frequency obtained by test of resonance frequency scanning is 37～39k Hz,which is consistent with the drive mode frequency of 38653 Hz calculated by theoretical simulation,The reliability of the structure and process parameters is also verified by the characterization of the gyroscope samples.