An embodiment of the instant invention is a method of etching a conductive structure comprised of copper and overlying a semiconductor substrate, the method comprising the step of: subjecting the conductive structure to a combination of plasma, an etchant, and a gaseous aluminum source. Preferably, the conductive structure is comprised of aluminum and copper (more preferably, it is comprised of aluminum and 1 to 4% by weight copper) or it may be substantially comprised of substantially pure copper. In addition, the etchant is preferably introduced into the process chamber in a gaseous state and is comprised of Cl.sub.2. The gaseous aluminum source may be comprised of: DMAH, trimethylaluminum, dimethylalane, trimethylaminealine, dimethylethylaminealane, dimethylethylaminedimethylalane, or AlCl.sub.3.