| Summary: | 碩士 === 國立清華大學 === 化學工程學系 === 87 === Abstract LIGA, one of the MEMS'' manufacturing technologies, fabricates microstructures with high aspect ratio. This process involves deep etched x-ray lithography, electroforming, and molding. Laser-LIGA process mentioned in the subject is different from the traditional LIGA because it utilizes excimer laser as light source instead of synchrotron x-ray radiation. Furthermore, the exposure mechanism called photoablation is also unlike others. After polymer surface absorbs the laser pulse, the breaking of chemical bonds will cause a sudden pressure increase and force material to be ejected in a mini-explosion.So this kind of lithography do not need development procedure in fact. After exposure it can create patterns in the resist layer immediately. The study aims at developing thick film resists satisfied with the wavelength characteristics of KrF laser in PIDC and the request for following electroforming process.This project will be carried out in the following procedures. The major contents include：1.preparing poly(methylmethacrylate) homopolymer as KrF laser thick resist and developing the fabrication technique of thickness from 300mm to 500mm.2.characterization and analysis of thick film resists'' properties.3.finding out the optimal exposure parameters to fabricate microgears with high aspect ratio.4.choosing MMA as the basic component and copolymerizing with methacrylic acid monomer to form copolymer thick film resist.5.studying the feasibility of improving the mechanical and physical properties of resists by this way.6.discussing the relationship between the exposure parameters and the copolymer resists'' properties.7.choosing the optimal copolymer resist to fabricate the micogear box.Results show that the PMMA microstructures with the near-vertical sidewalls can be produced under the proper control of experimental parameters. Moreover, the PMMA templates with aspect ratio of 25：1 have been achieved in a 300-mm-thick layer , and the sequential electroforming processes have realized the metallic microstructures. In this study the practical fabrication of the microgear by the laser LIGA processes is also presented.Otherwise we add MAA monomer to photoresist solution and try to improve the properties of thick film. The addition of MAA can increase the adhesion of PMMA thick film to substrate. Furthermore the threshold fluence of poly(MMA-co-MAA) film will also be reduced.
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