Electroless and electro-plating of Cu on Si

In this work, the deposition of copper onto silicon by either electro or electroless plating was investigated. Aqueous solutions with known concentrations of copper ions, with or without fluoric or sulfuric acid, were used. Surface morphology, composition and thickness of the deposited films were characterized by SEM, RES and profilometry. Deposition under the cathodic regime yielded a film with a non-homogeneous granular structure independently, whether hydrofluoric acid had been added to the electrolyte or not. Under the anodic regime, deposition also occurred, but only if HF was added to the electrolyte. In this case, the Cu deposits exhibited good adhesion, a metallic appearance and a homogeneous and compact granular structure with grain size of similar to 500 nm. In contrast to the electrodeposition, for the electroless deposition, adhesion of the film was poor and grain sizes were similar to 100 nm. For both electroless and anodic electrodeposition cases, silicon dissolution was observed.