Research On Structural Dynamics And Fabrication Process On A 2D MEMS Mirror

The 2D MEMS mirror obtains three-dimensional information by changing the exit angle of incident laser,reflecting,receiving and processing it by space objects.The application environment of vehicle LiDAR requires the micro-mirror reach enough reflective area to ensure the accuracy of incident light alignment and reduce assembly cost of alignment.High frequency(at KHz)motion is required to capture the object quickly.The large deflection angle is required to meet the requirements of a wide range of field of view.The problems above are focused and researched in the following aspects.Firstly,structure design and optimization of micro-mirror based on Newmark-? algorithm.By Lagrangian energy equation,the dynamic model under generalized coordinates was established.By mechanics of materials,the analytic solutions between structure parameters and spring stiffness or moment of inertia of mirror structure were established.The structure parameters were optimized design and analyzed by Newmark-? numerical integration method to obtain the angle matching of biaxial deflection under a certain proportional driving force.The ANSYS finite element static and dynamic analysis were carried out to simulate and verify the static and dynamic characteristics of mirror.Secondly,analysis of damping characteristics of micro-mirror working in atmospheric environment.The first-order viscous damping model was used to solve the air damping problem of the mirror and two-way FSI simulation was carried out to simulate the motion of the micromirror in the atmosphere.Therefore,the approximate solution of quality factors of three modes in the atmosphere were obtained.Besides,the values of quality factor of thermoelastic damping were derived by COMSOL and the relationship between different bending beam sizes and the quality factors was analyzed.Thirdly,design and implementation of micro-mirror based on bulk silicon MEMS technology.The fabrication process was based on 4-inch SOI wafer and the layout of the optimized mirror structure was designed by L-Edit layout design software.The mirror with buried 16?m extra deep Cu coils was processed with the process Equipment Support of Suzhou Nano Institute.Fourthly,morphology testing of single chip and experimental analysis of principle prototype.The fabricated single chip was tested to obtain its morphological characteristics.The response experiments of the mirror prototype were carried out to verify its response characteristics and damping characteristics in air.The tested maximum scanning angles of fast axis and slow axis were 10 ° and 50 ° respectively under the voltage of 5 V and the scanning frequencies are 8 KHz and 800 Hz respectively.The deflection angle of fast axis could obtain 20 ° under the voltage of 10 V.The tested quality factors of the mirror at fast and slow modes were 464.9 and 102 in air respectively.