Reliability of Complete Plasma Etched Ru/Cu Lines

Abstract

The reliability of oxygen plasma-etched ruthenium/copper thin film stacks was studied under constant-current density and constant-voltage stress conditions. The thin ruthenium served as an adhesion layer for copper. The lifetime of the ruthenium/copper line was determined from resistance-time measurements. The ruthenium/ copper line had a longer lifetime than the titanium tungsten/copper line. The line failure process started from voids formation followed by growth and merging, which could be correlated to the change of the surface topography, especially near the broken area. Ruthenium can be a promising barrier material for interconnect copper lines.