Cu electroplating using suspension of supercritical carbon dioxide in copper-sulfate-based electrolyte with Cu particles

An electroplating method with supercritical carbon dioxide (sc-CO2) suspension, which is named EP-SCS, is proposed in this study. Application of sc-CO2 emulsion in electroplating has been reported to be effective in reducing defects found in the plated materials. However, dissolution of the Cu seed layer was observed in the attempt to fill the nanoscale holes on a hole test element group. Therefore, Cu particle was added to form a suspension to inhibit the dissolution of the Cu seed layer. In this study, we found usage of the additives in the Cu damascene process can be reduced significantly by application of EP-SCS. Complete Cu fillings were obtained in the holes with 60 nm in diameter and aspect ratio of 2 by application of EP-SCS.

► An electroplating method with supercritical carbon dioxide suspension is proposed.
► Addition of Cu particles improved the current efficiency.
► Additives in the Cu damascene process can be reduced significantly by this method.
► Complete Cu fillings were obtained in 60-nm diameter holes