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

1. 在大功率x射线发生器上安装了一种新型二维探测器，用于测量直径约为50 μm的局部区域的应力。四点。研制了弯曲装置，实现了地应力测量。提出了一种利用二维探测器测量单晶应力的新方法。利用原子力显微镜（AFM）测定了铜薄膜中丘状和空洞的形成与热循环条件的关系。利用同步加速器x射线对热循环过程中的内应力进行了原位测量。实测结果与基于热膨胀、蠕变系数与铜膜塑性行为失配的预测结果吻合较好。成功地进行了电沉积铜薄膜的疲劳试验。细晶膜的疲劳寿命比粗晶膜长。半值宽度将作为一个参数来检测疲劳损伤的进展。在聚酰亚胺箔上溅射了一层铜薄膜。用x射线原位测量了铜膜的应力和半值宽度。评价了x射线参数的特征行为。采用电子背散射衍射（EBSD）方法测定了多晶样品中各晶体的取向。基于原子力显微镜（AFM）测量的表面形貌发展和ebsd的晶体取向分析，提出了多晶疲劳裂纹萌生的条件。建立了织构薄膜的有限元模型，系统地分析了试样尺寸对薄膜弹性特性的影响。通过分子动力学分析确定了纳米缺陷对硅单晶断裂行为的影响，并讨论了断裂力学方法的局限性。对铜薄膜进行了类似的分析，以确定纳米缺陷对薄膜中位错行为的影响。少

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