Study On Fabrication Process Of Torsion Balance Plate For Casimir Force Measurement

With the development of MEMS technology, the sizes of and the distances between the components in some MEMS devices are already in the sub-micrometer regime. Further miniaturization is carrying the MEMS technology into a domain where some quantum mechanical effects, hitherto neglected, will need to be taken into account. The Casimir effect, is the attractive pressure between two flat parallel plates of solids and it is not an electrostatic effect but a quantum effect. More and more researchers focus on how to measure the Casimir force accurately. The torsion balance system is the most widely used measurement tool, the plate of which is one of the most critical components that affect the accuracy.In this thesis, the plates of the torsion balance for Casimir force measurement have been fabricated by designing and optimizing the processing technology. As the plate is made up of silicon V-groove structure and glass substrate, the processes of silicon V-groove etching and silicon-glass bonding were investigated. The main work of this thesis includes:(1) Based on the analyses of the structure and materials of the plate, a low cost and few steps fabrication process for the torsion balance plates was designed. The silicon V-groove structure was etched by KOH wet anisotropic etching. The silicon was bonded to the glass substrate by using silicon-glass bonding technology.(2) Cut-and-try method was used to adjust the lithography process parameters to obtain a better pattern. Veeco Surface Profiler was used to measure the etching rate of nitride using RIE etching and the etching rate of silicon using KOH wet anisotropic etching. The mechanism of KOH anisotropic etching, the etching apparatus configuration and the etchant solution prescription were also discussed.(3) Taking advantage of the transparence of glass, UV-curing was applied to bond the silicon wafer to the glass substrate The bonding process details, including the pre-bonding mode, UV-curing system configuration and bonding process parameters were investigated. The bonding quality and intermediate layer were also analyzed.Experiment results demonstrate: the method is effective, simple and lower cost. The V-groove structure of the torsion balance plate using this process is precise and reliable. UV curing can be applied in the silicon-glass intermediate layer bonding and high bonding quality of the plate can be achieved.