In Situ SEM Observations of Electromigration Voids in Al Lines under Passivation

Abstract

Since the early work of Ilan Blech and Gene Meieran more than 20 years ago, electromigration (mass transport produced in a metallic conductor by current flow) has been recognized as an important reliability hazard for solid-state electronic devices. The continuing shrinkage of dimensions in VLSI devices has resulted in a continuing increase in the current density in the interconnection lines and a corresponding increase in the potential electromigration hazard. Although there have been improvements in the materials and structures used for interconnections, notably the addition of copper to aluminum and the use of layered structures, the provision of an adequate margin of safety has become increasingly difficult and is an important constraint on both device design and process development.