An alloy forming dopant material is deposited prior to the formation of a copper line, for instance by incorporating the dopant material into the barrier layer, which is then driven into the vicinity of a weak interface by means of a heat treatment. As indicated by corresponding investigations, the dopant material is substantially transported to the weak interface through grain boundary regions rather than through the bulk copper material (copper grains), thereby enabling moderately high alloy concentrations in the vicinity of the interface while maintaining a relatively low overall concentration within the grains. The alloy at the interface reduces electromigration along the interface.