Electromigration-induced copper interconnect degradation and failure: the role of microstructure

In this paper, EM-induced degradation processes and failure in on-chip interconnects are discussed based on experimental studies. In-situ microscopy studies at embedded via/line dual inlaid copper interconnect test structures show that void formation and evolution depend on both interface bonding and microstructure. In future, copper microstructure becomes more critical for interconnect reliability since grain boundary diffusion becomes increasingly important for structures with strengthened interfaces, i. e. interfaces are the fastest pathways for the EM-induced mass transport any more. Particularly, grain boundaries have to be considered as significant pathways for mass transport in copper interconnects.