We investigated the mechanism of chemical and galvanic corrosion of tungsten nitride carbide (WNXCY) barrier during Cu chemical mechanical planarization (CMP). Our results demonstrate that chemical corrosion is caused by the oxidation of tungsten (W) in the WNXCY film by H2O2 followed by the dissolution of a tungsten oxide complex, which leads to WNXCY loss. WNXCY loss is enhanced during CMP due to galvanic corrosion driven by the Cu/WNXCY couple. A high loss rate occurs due to the strong potential difference between Cu and WNXCY in H2O2-containing slurries. A model representing WNXCY loss in Cu damascene lines during the CMP process is proposed. It supports WNXCY loss in the top part of the trench sidewall at the interface with Cu. We demonstrate that the use of HNO3 instead of H2O2 as the oxidizer, in the formulation of the corrosion-inhibiting model slurries reduces chemical and galvanic corrosion of WNXCY. Addition of monosaccharides or organic acids prevents excessive Cu loss. Wafer-level tests done with in-house corrosion-inhibiting model slurries show promising Cu and WNXCY compatibility without significant WNXCY loss. (c) 2005 The Electrochemical Society.