High Density Copper Nucleation on Ruthenium and Its Application to Direct Plating of Advanced Interconnects

Abstract

Electrochemical nucleation of Cu on Ru in commercial chemistries was studied. The results show that Cu nucleation behavior is highly dependent on the suppressor species and concentrations, the acidity of the electrolyte, and the state of Ru surface. With an excellent suppressor and intermediate acid electrolyte, the Cu nucleation density as high as 1 ×1013 cm-2 can be achieved without the need of a pretreatment of the Ru surface. Direct plating of Cu on Ru with both damascene and through-silicon via structures using this highly suppressive chemistry is demonstrated.