Seedless electrochemical deposition (ECD) can generate good adhesion of copper on TaN and Ta diffusion barriers using a saturated KOH solution and a copper-citrate complex electrolyte. The interfacial fracture energy of the Cu/TaN or Ta interface was quantitatively measured by four-point bending method. The load increased linearly with interfacial crack growth due to the plasticity of ductile copper and the elastic bending of the Si substrate. The delamination energy was proportional to the thickness of seedless ECD copper, which was in the range of 180-980 nm. The delamination energy in the steady state, G(ss), of 5-24 J m(-2) was attained. (c) 2006 The Electrochemical Society.