Electromigration
Resistance to electromigration, the process by which a metal conductor changes shape under the influence of an electric current flowing through it and which eventually leads to the breaking of the conductor, is significantly better with copper than with aluminium. This improvement in electromigration resistance allows higher currents to flow through a given size copper conductor compared to aluminium. The combination of a modest increase in conductivity along with this improvement in electromigration resistance was to prove highly attractive. The overall benefits derived from these performance improvements were ultimately enough to drive full-scale investment in copper-based technologies and fabrication methods for high performance semiconductor devices, and copper-based processes continue to be the state of the art for the semiconductor industry today.
Read more about this topic: Copper Interconnect