Electromigration in two-level bamboo grain structure Al(Cu)/W interconnections

Abstract

Electromigration in two-level Ti/Al(0.5%Cu)/Ti lines with interlevel W stud interconnects has been investigated using both drift velocity and resistance techniques. It is shown that the mass depletion from the cathode end correlates with resistance change and electromigration failure in line/stud chains. The mean time to failure was found to be weakly dependent on linewidth from 1.9 μm (two grains across any linewidth) to 0.7 μm (bamboo structure). The dominant mass transport path is along the edges of the metal line.