Abstract: Manufacturing a damascene structure involves: forming a sacrificial layer (20) on a substrate (10) to protect an area around a recess (30) for the damascene structure, forming a barrier layer (40) in the recess, and in electrical contact with the sacrificial layer, forming the damascene structure (50) in the recess, and planarizing. During the planarizing the sacrificial layer reacts electrochemically with the barrier layer or with the damascene structure. This can alter a relative rate of removal of the damascene structure and the sacrificial layer so as to reduce dishing or protrusion of the damascene structure, and reduce copper residues, and reduce barrier corrosion. The barrier layer can be formed by ALCVD. The barrier material being one or more of WCN and TaN. The sacrificial layer can be TaN, TiN or W.