BEHAVIOR OF CU(P) AND OXYGEN FREE HIGH CONDUCTIVITY CU ANODES UNDER ELECTRODEPOSITION CONDITIONS

Films formed on Cu(P) (with 0.1 atom percent P) and oxygen free high c onductivity Cu anodes in electroplating solutions were studied by a ne wly developed gravimetric technique, electrochemical methods, x-ray ph otoelectron spectroscopy, and x-ray absorption spectroscopy. The black film formed on Cu(P) in Cl--containing solutions was found to resembl e a porous sponge composed of CuCl but laden with concentrated CuSO4 s olution. The gravimetric experiments show that the difference between the buoyancy-corrected measured mass change and the charge-equivalent mass change has two components: a reversible part that comes and goes as the current is turned on and off, and an irreversible part that rem ains on the surface and increases in mass with time as dissolution pro ceeds. The reversible part of the mass change arises from the weight o f the diffusion layer. The irreversible part results from the anodic f ilm, which increases linearly in mass with charge density but at a rat e that is independent of current density. P inhibits the disproportion ation of Cu+1 that results in the poorly adherent anodic film that for ms on OFHC Cu anodes.