Research On Critical Technologies Of The Wafer-level Vacuum Packaging Based On TGV For The Butterfly Microgyroscope Drived By Tangential Force

MEMS?Micro-Electro-Mechanical System?wafer-level vacuum packaging can not only provide necessary protection and steady work environment for MEMS devices,but also have lots of advantages like smaller packaging size,lower cost and higher efficiency than device-level vacuum packaging.TGV?Through Glass Via?technology based on glass reflow is used for the MEMS wafer-level vacuum packaging due to its capability to achieve signal's vertical interconnection.It can further reduce the packaging size.Moreover,it is one of the most important methods to achieve MEMS' 3D integration.Besides,it becomes a hot spot in MEMS packaging field due to its high insulating property and little parasitic capacitor.However,the researches for the packaging scheme,especially for glass reflow and airtightness enhancing technology,are not enough.Therefore,the TGV technology based on glass reflow is researched in this paper,and the wafer-level vacuum packaging for butterfly gyroscope drived by tangential force is achieved.The major contents include:1.Introduce the background and significance of the research.By investigating the study states of MEMS wafer-level vacuum packaging all over the world,know about its trend and summarize the advantages and problems of the wafer-level vacuum packaging scheme based on TGV.2.Design the structure of the butterfly microgyroscope drived by tangential force.According to the principle of the tangential electrostatic force,we design the butterfly microgyroscope that is drived by tangential force while detects angular velocity by the changes of capacitance in the normal direction.Besides,the structure for the wafer-level vacuum packaging,TGV-gyroscope-glass cap,was also designed.3.The theoretical analysis,simulation and experimental verification for the critical technology-glass reflow.Propose the equivalent circuit theory to describe glass reflow process,and deduce the relationship between reflow depth and all the influential factors,such as temperature,heating time,pressure,width of gap and surface tension;simulate this glass reflow process through COMSOL software and verify the deduced theory; design the experiment to demonstrate the theory's accuracy;Results show that the theoretical deduction can be used to instruct the glass reflow process.4.The research for enhancing airtightness and the verification of the TGV's airtightness.Propose that add a layer of SiO₂ to enhance the airtightness between silicon and reflowed glass by analyzing the theory of interfacial energy,and design experiments to see whether the method is efficient;conduct the experiment to verify TGV has ability to achieve the vacuum packaging;explore the anodic bonding technology and conduct the verification experiment.5.The design of the whole technological process and the research of the critical technologies in TGV.Design the steps of fabricating TGV;study the critical technologies in TGV fabrication process,such as DRIE,glass reflow,wafer reduction and CMP.6.The technologies of the wafer-level vacuum packaging based on TGV for the butterfly microgyroscope drived by tangential force were explored.Gyroscopes and glass caps were got respectively,and the packaging structure of TGV-gyroscope-glass cap was also achieved by the strong anodic bonding.