| Multilayer thin films are widely used in semiconductor devices and electronic packaging. In multilayer thin films, thermal stress, induced from mismatch in thermomechanical properties between constituents of each layer, causes micro mechanical failures such as interface delamination, cracking, yielding and creep. Thus, the evaluation of thermal stress evolution and its effects on the deformation behavior of multilayer system is very important. We presented an analytical model on thermal deformation of multilayer thin films on the basis of elastic/plastic beam bending theory concerning bending stress of the film layer. By using the model, we studied a common interconnection system in semiconductors. We deposited Al(1%Si) thin film and SiO₂ passivation layer of different thicknesses on Si wafers. In-situ laser scanning method was performed to measure the thermal stress induced curvature of the system. By applying the model to the measured curve of curvature vs. temperature, we could ascertain the validity of the model. |
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