Experimental study to validate a model of hillock's formation in aluminum thin films

The growth of holes and hillocks in thin films has been reported extensively and for a multitude of film-substrate systems. A recently developed model [F. Y. Genin, J. Appl. Phys. 77, 5130 (1995)] which analyzes the formation of a ridge at a traveling grain boundary due to stress and capillarity driving forces provides a quantitative description of the growth of the hillocks. In order to test the model, the surface morphology of aluminum thin films deposited on oxidized silicon substrates and annealed at 450 degrees C in argon is investigated; the profiles of thermal hillocks are measured by atomic force microscopy. The comparison shows excellent agreement between modeled and experimental profiles.