Copper interconnections and reliability

The materials, processes, and reliability issues in the development of multi-level Cu chip interconnections are described. Fully integrated four-level Cu/polyimide structures have been fabricated by using a damascene process which maintains planarity at each level. Electromigration lifetime for two-level Cu interconnections is found to be more than two orders of magnitude longer than that of Al(Cu) while having approximately twice the conductivity. © 1998 Elsevier Science S.A.