Influence of initial microstructure and impurities on Cu room-temperature recrystallization (self-annealing)

The initial microstructure of thin electroplated Cu films was investigated for different layer thicknesses and plating conditions. The initial grain size of electroplated Cu thin films was found to be distributed homogeneously whereas the initial texture was inhomogeneous over film thickness. With increasing film thickness a transition occurs from a basis-oriented into a field-oriented texture. The knowledge about initial Cu microstructure for different plating conditions helped to clarify the factors of influence for Cu room-temperature recrystallization, called self-annealing. Furthermore, beside the microstructure also incorporated impurities were found to be of great importance for Cu self-annealing particularly in the case of a varying additive content in electrolyte.