Abstract: Stresses in epitaxial and textured Al films were determined by substrate-curvature measurements. It was found that in both cases the flow stresses increase with decreasing film thickness. The flow stresses in the epitaxial Al films are in agreement with a dislocation-based model, while the same model strongly underestimates the flow stresses of textured Al films. In situ transmission electron microscopy studies indicate that dislocations channeling through epitaxial Al films on single-crystalline (0001) a-Al2O3 substrates frequently deposit dislocation segments adjacent to the interface. Furthermore, the Al/a-Al2O3 interface acted as a dislocation source. In this case, the interface is between two crystalline lattices. In contrast, the interface of textured Al films on oxidized silicon substrates is between the crystalline Al and the amorphous SiOC interlayer. It is speculated that the different nature of the interfaces changes dislocation mechanisms and thus influences the flow stresses.

Key words: Thin film, Plasticity, Dislocation, Interface