Additives for Super-conformal Electroplating of Ag Thin Film for ULSIs

Abstract

For Ag electroplating in a damascene structure, two additives were tried in the electrolyte composed of KAg(CN)2 and KCN. One additive, thiourea, played a role as a suppressor and a brightener on a Ag seed layer. The other additive, benzotriazole, worked as an inhibitor on a Cu seed layer whereas it acted as an accelerator on the Ag seed layer. When these two additives were added to the electrolyte, the superconformal electroplating of Ag thin film for ultralarge scale integrateds ~ULSIs! was accomplished successfully without defects in the damascene structure with a width of 400 nm and an aspect ratio was 4.