Microscopic Fracture Mechanics Study on Fatigue Micro Mechanisms of Thin Films by Micro Beam X-Ray Stress Evaluation

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1. A high-power X-ray generator was equipped with a new two-dimensional detector to measure the stress in a local area of about 50 μm in diameter. A four-point.bending device was developed to enable the in-situ stress measurement. A new method was proposed to measure the stress in a single crystal using the two-dimensional detector..2. Using atomic force microscopy (AFM), the formation of hillocks and voids in copper thin films was determined as a function of thermal cycling conditions. In-situ measurements of the internal stress during thermal cycling was conducted using synchrotron X-rays. The measured results agreed fairly well with the prediction based on the mismatch of the coefficient of thermal expansion and creep and plastic behaviors of copper films.3. Fatigue tests of electrodeposited copper thin films were successfully conducted. The fatigue life was longer in fine grained films than coarse grained films. The half-value breadth will be a parameter to detect the progress of f … More atigue damage.4. A copper thin film was sputtered on a polyimide foil. The stress and the half-value breadth in copper films were measured in-situ by X-rays. The characteristic behavior of the X-ray parameters was evaluated.5. Electron back scattered diffraction (EBSD) method was used to determine the orientation of each crystal in polycrystalline specimens. The condition of fatigue crack initiation in polycrystals was proposed on the basis of the development of surface topography measured by AFM and the orientation analysis of crystals by EBSD.6. A finite element model of textured thin film was developed and the effect of the specimen size on the elastic characteristics of thin films was systematically analyzed.7. Molecular dynamic analysis was conduced to determine the effect of nano-sized defect of the fracture behavior of silicon single crystals, and the limitation of the fracture mechanics approach was discussed. A similar analysis of copper thin films was conducted to determine the effect of nano-sized defect on the dislocation behavior in thin films. Less