Research On Piezoelectric-Driven Micromirrors Based On Mechanical Cutting And Eutectic Bonding Processes

In recent years,with people’s research in-depth to micro-nano level,MEMS(micro-electro-mechanical system)technology has been developed rapidly,which spans multiple disciplines and integrates multiple fields.The miniature drive device that powers the microsystem has also become one of the current research hotspots.In this context,a piezoelectric-driven micromirror based on mechanical cutting and eutectic bonding process is designed and prepared.Combined with a variety of MEMS processing technology,the preparation of piezoelectric drive micromirror was completed,and the preparation process was detected and analyzed,and some optimization schemes were proposed,and the problems in the eutectic bonding process of PZT and Si in the preparation were studied by tensile experiments.The designed piezoelectric drive micromirror consists of two parts: silicon mirrors and PZT driver.By comparing the characteristics of different materials,the material of the mirrors and the piezoelectric driver was determined.The finite element simulation software COMSOL Multiphysics was used to optimize the structure of silicon mirrors in piezoelectrically driven micromirrors.The preparation of piezoelectric-driven micromirrors was completed by physical vapor deposition,ultraviolet lithography,eutectic bonding,mechanical cutting and DRIE(deep reactive ion etching).The relationship between PZT-Si eutectic bond strength and bonding temperature,bonding time,intermediate Au layer thickness and polarization order was tested by tensile experiments.Three to five samples were prepared and measured under each condition,and their mean values and variations were assessed.Combined with the fracture optical photo and the SEM photo,the internal causes of the bond strength change during eutectic bonding were analyzed.The dielectric properties of PZT under eutectic and non-eutectic bonding conditions were tested using an LCR analyzer.The laser interferometer was used to detect the morphology of silicon mirrors after each process step.The test results show that the prepared piezoelectric drive micromirror can achieve a maximum deformation of 0.6μm in the positive direction and 1.7μm in the negative direction when loaded with a voltage of ±1.5k V.The causes of non-uniform deformation of silicon mirrors are emphatically discussed and some methods for optimizing the process are put forward.