In situ Observation of Grain Growth on Electroplated Cu Film by Electron Backscatter Diffraction

Abstract

In situ observations using an automated electron backscatter diffraction (EBSD) system with a heating stage were carried out to clarify the mechanism of grain growth on electroplated Cu and Cu deposited by physical vapor deposition (PVD). Hardness measurements and EBSD observations revealed that the strain in electroplated Cu and Cu deposited by PVD was released by annealing. Little preferential orientation of the texture was observed in electroplated Cu, while Cu deposited by PVD showed strong (111) texture. A greater number of twin boundaries were observed in electroplated Cu than in Cu deposited by PVD. Grains surrounded by random grain boundaries were more enlarged by annealing in electroplated Cu than those in Cu deposited by PVD. Since segregation of impurities with a low melting point, such as sulfur, to grain boundaries could promote grain growth, which is often accompanied by twin boundary formation, the reason that many twin boundaries are found in electroplated Cu is considered to be the existence of impurities such as sulfur at grain boundaries. The effect of a twin grain boundary on resistivity was calculated and the contribution of a twin grain boundary to resistivity was found to be much less than that of a random grain boundary.