Effect of film thickness and annealing temperature on hillock distributions in pure Al films

The dependence of hillock distribution on film thickness and annealing temperature has been studied in pure aluminum films. The densities and diameters of hillocks were analyzed after 6 h of annealing. As the film thickness increases, the hillock density decreases and the average diameter increases. The total volume of hillocks per unit area of the film increases linearly with both the film thickness and the annealing temperature. Using a model based on stress relaxation, a simple equation which can predict the hillock density and average hillock diameter is suggested.