A MECHANISM FOR ELECTROLESS CU PLATING ONTO SI

In this work the electrochemical mechanism of copper plating on silico n during immersion into diluted hydrofluoric acid (D-HF) solutions is investigated. For that purpose, silicon wafers were immersed for vario us time intervals into D-HF intentionally contaminated with copper fro m copper sulphate. The RES analysis of the plated films revealed the p resence of oxygen at the copper-silicon interface. It was found that c oncomitantly to the copper film deposition silicon consumption occurre d at a ratio of 1:1 (one consumed silicon atom for one plated copper i on) instead of the ratio of 1:2 usually accepted for silicon dissoluti on in presence of fluoride ions. In conclusion, a new electrochemical copper plating mechanism is proposed.