Activation energy determination for recrystallization in electroplated-copper films using differential scanning calorimetry

The apparent activation energy for recrystallization during self-annealing of 1.5-µm-thick electroplated copper films was determined using constant-heating-rate scans in a differential scanning calorimeter (DSC). The apparent-activation energy was measured to be 0.62 eV/atom. Ex-situ microscopy studies showed that self-annealing in electroplated Cu films is characterized by site-saturated nucleation and diffusion-limited, two-dimensional grain growth. For a transformation with these characteristics, the apparent activation energy measured using a differential scanning calorimeter corresponds to the activation energy for grain-boundary motion. The measured activation energy is reasonably close to values reported for grain boundary motion from in-situ microscopy studies. The value is also close to the activation energy for grain boundary diffusion in Cu. This work demonstrates the feasibility of using differential scanning calorimetry (DSC) as a relatively straightforward method to study the kinetics of the self-annealing process.