Modeling and Experimental Study of Wafer Manufacturing and Machining Processes
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To achieve the stringent requirements for the future specification of wafers, the progress in wafering processes such as slicing, lapping, grinding, and polishing is critical. The improvement of the existing technology and the innovation of advanced machining tools are necessary for the future wafer production. For example, study of vibration of a moving wire in slurry wiresaws and active control of such vibration can reduce kerf loss, and in turn reduce the cost of wafer manufacturing. Such study can also contribute to a better surface finish with less subsurface damages. Mixed abrasives in slurry can increase material removal rate in lapping to reduce time of machining and cost. In this dissertation, the research on the vibration of the wire in the slurry wiresaw system, mixed abrasive effect in lapping process, and wafer surface finishing by CNT brush are studied. Both free and forced vibration response of damped axially moving wire are derived by modal analysis and the Green's function, respectively. The eigensolutions, orthogonality, frequency of damped vibration, and frequency response with a point excitation are also obtained. Two different sizes of abrasives, F-400 and F-600 SiC, are mixed with different ratios in the slurry for lapping process. The results show that mixed abrasive grits can enhance the material removal rate. However, the surface roughness becomes slightly worse. CNT brush is introduced as a new polishing tool. Preliminary experimental results are presented.