Copper grain growth in thin film Cu-Cr multilayers

Copper-chromium multilayers with a 25 nm repeat distance were prepared by dual gun sequential magnetron sputtering. The mutual immiscibility of the two elements ensures that no interdiffusion or reaction takes place at the deposition temperature. High temperature X-ray diffraction runs were carried out in the 370-630°C temperature range, at constant time intervals. At elevated temperature, the Cu(111) reflection showed increasing intensity and decreasing line-width as a function of time. Analysis of the line narrowing as a function of the annealing time and temperature allowed deduction of the activation energy, 0.41 ± 0.05 eV per atom, associated with the atom mobility involved in the copper grain growth.