Hillock growth on aluminum and aluminum alloy films

Abstract

The size distributions of hillocks formed on Al and Al alloy films were measured and related to their growth mechanisms. The compositions of these films were as follows: pure Al, Al–1.7wt.%Cu, Al–7.6wt.%Cu, Al– 15wt.%Cu, and Al–1.7wt.%Cu–<1wt.%Si. They were formed under a variety of experimental conditions. In almost all cases the hillock size distributions were log-normal, which, in analogy with the nucleation and growth of thin films, is the distribution that would be expected for hillock growth by mobility coalescence. In the case of the Al–15wt.%Cu films, which were isothermally annealed in vacuum at 300 °C, the distributions gradually changed from log-normal initially to one that had some of the characteristics of Ostwald ripening.