Growth of electrodeposited copper on anodized titanium

Abstract

Copper electrocrystallization at high current density was studied in a pure copper sulphate-sulphuric acid bath. Besides the influence of the current density and electrolyte flow rate, the influence of the titanium substrate pretreatment on the nucleation and growth of copper is emphasized. The 100 μm thick copper deposits give two different layers. The layer in contact with the substrate shows a high density of very small crystals and corresponds to the unoriented dispersion (UD) type in the Winand diagram. The structure of the layer in contact with the electrolyte is, on the contrary, mainly controlled by the electrodeposition parameters (current density and electrolyte flow rate) and corresponds to a field oriented (FT)-UD type in this diagram. It is shown that the thickness of the transition zone between the substrate influenced deposit and that controlled by the electrodeposition parameters depends on the anodic oxidation conditions of the substrate pretreatment. The copper deposits were separated from their substrate and analysed by TEM (including cross-sections), SEM and X-ray diffraction. Some copper foils recrystallize at room temperature.