;Thermal compression bonding (TCB) was one of frequently used technique in semiconductor packaging process. In TCB technique, the purpose of applying external stress is increasing the contact area between interface, while the elevated temperature could enhance the mobility of atoms for inter-diffusion to eliminate the interface and further accomplish bonding. The mechanical properties of joints were significantly related to their microstructure. However, most of research only focus on the effect of bonding temperature and bonding time on the microstructure. The discussion about the external stress effect on the microstructure is limited. Therefore, we would figure out the uniaxial external stress effect on the microstructure evolution of electroplated Cu films during TCB process. To simulate the thermal compression bonding process, the electroplated Cu films were stressed during thermal annealing. The external compression stress effect on microstructure of electroplated Cu films during TCB process could be discussed by the observation of the difference in microstructure with applying a different level of external stress. In chapter 4, we observed that the microstructure of electroplated Cu films changed with different level of external stress. Besides, microstructure changed by external stress most obviously in 373K. With grain size distribution analysis, we deduced that the external stress would change the grain growth mode of electroplated Cu films from normal grain growth mode to abnormal grain growth mode during thermal annealing. By analyzing the orientation of those abnormal grains, we observed that the initial generated abnormal grains reveals no preferred orientation. In chapter 5, the external stress effect on the grain growth kinetic of electroplated Cu film have been calculated. By analyzing the microstructure of annealed electroplated Cu films with external stress through transmission electron microscope (TEM), subgrain boundaries were comprised of dislocations which generated at the interface of abnormal grains and fine grains. From the analysis results and discussion, this research proposed the mechanism of uniaxial external stress effect on the microstructure evolution of electroplated Cu films during thermal annealing process.
