In-situ study on the self-annealing behavior of electroplated Cu through the cantilever method, XRD, and EBSD

• In-situ investigation on the self-annealing behavior of electroplated Cu
• Rapid recrystallization occurred with high current density deposition.
• 〈111〉 is the orientation developing as a result of self-annealing.
• Impurity redistribution with the internal stress relaxation during self-annealing
• Incubation time of Cu self-annealing

It is well-known that self-annealing of as-electroplated Cu would cause remarkable microstructure transition in few hours, inducing grain growth accompanied by elimination of grain boundaries and redistribution of impurities and crystallographic defects that determine the physical/chemical characteristics (e.g., resistivity and internal stress) of the entire Cu film. We carried out an in-situ study on this strongly time-dependent phenomenon to probe into crystallographic/microstructure and strain transitions in the self-annealing procedure. The crystallographic evolution of electroplated Cu, including grain size distribution, crystallographic orientation, grain boundaries, and residual strain, were investigated by means of in-situ X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). Moreover, grain orientation spread (GOS) value was obtained via the EBSD analysis, which offers valuable information regarding the residual strain distribution in the Cu platings. The internal stress of electroplated Cu was examined via a cantilever method. Additionally, effects of self-annealing on the impurity redistribution were investigated by a time of flight secondary ion mass spectrometer (TOF-SIMS). The knowledge advances our understanding of the evolution of the electroplated Cu physical/chemical properties during self-annealing.