DEFORMATION MECHANISMS OF AL FILMS ON OXIDIZED SI WAFERS

The mechanism for plastic deformation of 0.5 mum thick, 0.5 mum grain- size evaporated Al films on oxidized Si wafers has been studied using wafer curvature measurements over a temperature range from room temper ature to 500-degrees-C. Extensive evidence for both morphology changes and plastic deformation was obtained. Transmission electron microscop y confirmed the occurrence of grain growth, and stress changes attribu ted to recrystallization were observed. Deformation under tension coul d be explained by dislocation glide according to the kinetics observed in bulk Al at the same temperatures, stresses, and grain sizes. The k inetics of deformation under compression were investigated at 400-degr ees-C and were completely different from those under tension. This is either due to a difference in the deformation mechanism or to the occu rrence of work softening.