Effect of film thickness and annealing temperature in stress-induced damage in metal films

Hillocks were observed in various thick Al films after annealing for a long time and their density and diameter were measured using an image analysis program. The hillock density decreased while the diameter increased with increasing film thickness. The total hillock volume per unit area of the film is linearly proportional to the film thickness and annealing temperature. Based on the results of our investigation, the effect of the film thickness, grain size and annealing temperature on hillock formation is discussed, and an equation that can be used to predict the hillock density and average hillock diameter is suggested.