Reduced electromigration of Cu wires by surface coating

Abstract

Electromigration in on-chip Cu interconnections with a selective electroless metal coating, CoWP, CoSnP, or Pd, on the top surface of Cu damascene lines has been investigated. The 10–20 nm thick metal cap significantly improves electromigration lifetime by providing protection against interface diffusion of Cu which has been the leading contributor to metal line failure by electromigration.