A model for hillock growth in Al thin films controlled by plastic deformation

The dependence of total hillock volume (per unit area) on film thickness and annealing temperature has been studied in pure aluminum films. The total hillock volume (per unit area) increases linearly with both the film thickness and annealing temperature. Other characteristics involve a critical temperature and a critical thickness for hillock formation. It is shown that these phenomena can be explained by assuming that hillock growth is controlled by plastic deformation in the surrounding film. A simple analytical model is developed to account for these observations.