Research On Key Technology Of Micro-gyro Process With Double-layer Grating In-plane Detection

As one of the core devices in micro inertial system,micro gyro is mainly used to measure the angular velocity of the carrier,which has very important applications in the fields of military guidance,unmanned aerial vehicles and civil car navigation,maritime positioning and so on.Micro gyro has many advantages such as small size,low power consumption and low cost.High-precision micro-gyro products and technologies are strictly controlled by foreign countries,and the application of double-layer grating detection displacement to micro-gyros is expected to break the limits of current mainstream detection methods such as capacitance and piezoelectricity.This paper proposes a micro-gyro that uses double-layer grating in-plane detection,and studies its key manufacturing process.This article mainly completes micro-gyro structure simulation and calculation,micro-gyro process design,process production,bonding test,structural characterization and natural frequency test analysis.The main research contents are as follows:First,the principle of the double-layer grating micro-gyro is introduced,that is,under the action of the Corelli Force,the dynamic and static gratings are displaced in the plane,which makes the diffracted light intensity change.The displacement signal is extracted by detecting the light intensity change,and finally the angular velocity is obtained by demodulation.Simulates the micro-gyro to calculate that the structure sensitivity under atmospheric pressure is 5.665×10-9 m/°/s,and the total sensitivity is 10 m V/ °/s,the quality factors of the driving and detection directions are 3946 and 4226,respectively,the mechanical bandwidth of the micro-gyro is 11 Hz,and the noise level is 0.27 °/h/?Hz.Then completed the silicon wafer process,the glass wafer process,the layout design and the process flow design,and the selection of the bonding method was analyzed and selected.Through experiments,a photolithography model and anode model were established.It is determined that the metal barrier layer is adopted to avoid pull-in failure,and the anodic bonding method is adopted to form the Al-Al interconnection channel to provide an electrical channel for subsequent adjustment of the upper and lower grating spacing.After that,the silicon wafer and glass were processed by dry process,wet process,long film and other processes,and the silicon glass was anodic bonded.Finally,the anodic bonding wafer was scanned by C-SAM that showed no defects.The Al-Al interconnection interface was analyzed to show that the interconnection was formed.The anodic bonding was tested for shear strength,and the average shear strength was33.94 Mpa.The device was subjected to a shock test,and there is no obvious change in the interconnect resistance before and after the shock.The overall structure of the gyro was tested by scanning electron microscopy,and the width of the beam and the thickness of the mass block were tested and analyzed.The overall structure of the gyro meets the design requirements and the manufacturing error is controlled within 5%.In the atmospheric pressure environment,the device drive intrinsic frequency is 7675 Hz,the detection intrinsic frequency is 7703 Hz,the maximum relative error with the dynamic simulation result is 5.6%,and the frequency difference between driving and detection is 28 Hz.