Microstructure modulation for resistance reduction in copper interconnects

Microstructure variation with post-patterning dielectric aspect ratio (AR) and post-plating annealing temperature has been investigated in Cu narrow wires. As compared to the conventional annealing at 100 C for a feature AR of 2.6, both elevated temperature anneals and reduced AR structures modulated Cu microstructure, which then resulted in a reduced rate of electrical resistivity increase with area scaling and an increased electromigration resistance in the Cu narrow wires.