Electromigration (EM) phenomena are generally and quite accurately attributed to electron flow enhanced grain boundary diffusion processes. However, there is clear evidence in the literature and in the work that will be presented, that surface or interface diffusion phenomena also contribute to electromigration damage (EMD) in Al, Cu, and alloy films. Most of this evidence comes from transmission and scanning electron microscope experiments carried out on samples that have experienced the latter stages of EMD stressing. Evidence for surface or interface diffusion occurs in hillock formation and annealing, film thinning, voiding and island formation, and regrowth-healing events on current reversal. The implications of these results in attempting to reduce EMD in microelectronic metallizations are presented.
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