Effects of composition and structure on electromigration kinetics in aluminum-alloy thin films

Variations in time to failure data for electromigration processes have shown the importance to conductor design of factors that include composition, grain size, and passivation thickness. Traditionally, these variables have been studied separately. An understanding of the combined effects of these variables is necessary to design reliable conductors. Temperature-ramp resistance analysis to characterize electromigration (TRACE) has been applied to sample groups in which composition, passivation thickness, and grain size were varied. The results of these experiments provide the kinetic parameters for electromigration, and from these values, a calculation is proposed that allows an estimate of the conductors’ resistance to electromigration. The results suggest that the predominant factor controlling electromigration rates is the passivation thickness.