Characteristics of Thin Cu Films Electrodeposited On Textured Ni-Co Substrates

Abstract

An attempt has been made to study the effects of current density and the texture of the underlying substrate on electrodeposited copper. For this purpose five Ni-Co alloys, Ni-10 Co, Ni-20 Co, Ni-30 Co, Ni-40 Co and Ni-60 Co, in the cold rolled as well as in the annealed conditions, were used as substrates. Acid copper sulfate solution was used to deposit thin Cu layers on the substrates, using a Cu plate as anode, at four different current densities, 1, 10, 30 and 50 mA/cm2. The thickness of the electrodeposited Cu layer increased nearly linearly with current density, but was independent of the texture and composition of the underlying substrate. In general, the X-ray diffraction line intensities for the deposited Cu layer sharpened and those for the substrate Ni alloys weakened with increase in current density. The textural developments in the Cu deposits appeared to be quite independent of the textures as well as the compositions of the substrate materials. The deposited Cu layers did not inherit the textures of the substrates at the lower current densities, and also developed their own textures at higher current densities. The Cu (220) peak ultimately became the strongest XRD peak for the electrodeposited layer. The surface roughness of the deposited layers was distinctly smoother for the annealed substrates, as compared to the cold rolled Ni-Co alloys.