Electromigration Characteristics of Cu and Al Interconnections

Abstract

ABSTRACTElectromigration activation energies (Ea) of Al and Cu interconnections are strongly dependent on the grain boundary morphology, and it is pointed out that Ea of bamboo-like Al interconnection is not less than Ea of small grain Cu interconnections. Small resistance oscillatory changes caused by electromigration, which are classified into three categories; oscillation, downward spikes, and upward spikes, are investigated in detail. It seems most likely that oscillations correspond to annihilation and formation of the one void. It is also pointed out that downward spikes are local, while upward spikes are non-local. Dislocation dynamics such as generation, rapid transport and subsequent annihilation are considered to be origins of spikes.