| MEMS scanning mirror is a core component of MEMS lidar system,and can obtain three-dimensional information of space objects.In recent years,with the rapid development of the intelligent vehicles,MEMS lidar,as one of the core sensors,has drawn extensive attention.The vehicle-mounted lidar puts forward the following requirements for MEMS scanning mirror: a large reflective area;a high-frequency vibration(k Hz),and a large deflection angle.These requirements have become the urgent issues for high-precision and high-resolution MEMS scanning mirror.In order to meet the requirements of vehicle mounted,improve the resonant frequency and deflection angle,a double comb-drived MEMS scanning mirror based on the principle of electrostatic repulsion is designed in this master’s dissertation.The overall structure of the scanning mirror consists of a silicon substrate layer,a scanning mirror structure layer,and a glass cap layer.The structure layer of the scanning mirror is composed of an actuator with double comb,an S-type torsion beam and a lens body.The scanning mirror structure is modeled by SOLIDWORKS,and the sensitivity and reliability of the designed MEMS scanning mirror are analyzed and verified by using the simulation software MAXWELL,ANSYS and COMSOL.The simulation results show that the double comb-drived MEMS scanning mirror can effectively increase the deflection angle to ±13.46° at a driving voltage of 110 V.Moreover,the resonant frequency of the scanning mirror is 1.79 k Hz,which is much higher than other high-order modes.Therefore,it has an excellent working bandwidth and can effectively suspress the cross interference motions of other non-working modes.Based on modeling and simulation results,the mask layout of double comb-drived MEMS scanning mirror is completed by using L-edit software,and the fabrication processes of the proposed MEMS scanning mirror are designed by using micromachining technology.First,the combs,torsional beams,frame and the mirror structure are etched by reactive ion etching technique.The vertical interlacing structure of the comb teeth is realized by releasing technology and the vacuum encapsulation of the whole structure is completed by silicon-glass bonding technology.Moreover,the Al metal electrode and the ITO transparent conductive film are deposited by magnetron sputtering technology.Finally,the mask layout and fabrication processes of the proposed double comb-drived MEMS scanning mirror can be used for the fabrication of the devices. |
