Copper films were directly electrodeposited on a TaN diffusion barrier from specially designed electrolytes that contribute to good adhesion between copper and TaN. A very stable oxide film formed on the TaN surface when TaN was exposed in air. The tantalum oxide layer was removed by applying an anodic potential in a saturated KOH solution. The TaN surface in oxide free condition serves as an energetically favorable platform for highly adherent copper deposition in a copper-citrate complex solution. Careful selection of electrochemical parameters such as chemical composition, current, applying voltage, and time led to quality copper deposits on TaN with strong adhesion. (c) 2005 The Electrochemical Society.