Deformation mechanisms of Al films on oxidized Si wafers

The mechanism for plastic deformation of 0.5 µm thick, 0.5 µm grain-size evaporated Al films on oxidized Si wafers has been studied using wafer curvature measurements over a temperature range from room temperature to 500 °C. Extensive evidence for both morphology changes and plastic deformation was obtained. Transmission electron microscopy confirmed the occurrence of grain growth, and stress changes attributed to recrystallization were observed. Deformation under tension could be explained by dislocation glide according to the kinetics observed in bulk Al at the same temperatures, stresses, and grain sizes. The kinetics of deformation under compression were investigated at 400 °C and were completely different form those under tension. This is either due to a difference in the deformation mechanism or to the occurrence of work softening.