Polyether Suppressors Enabling Copper Metallization of High Aspect Ratio Interconnects

Void-free bottom-up fill in aggressive interconnect geometries, i.e., aspect ratio exceeding 20, requires suppression stronger than that provided by the conventionally used poly(ethylene glycol) (PEG). Reported here are polarization studies of copper electrodeposition in the presence of several polyethers, which heretofore were not studied in the context of bottom-up fill. Several of these compounds (including polyoxyethylated β-naphthol and polyoxyethylene lauryl ether) exhibit superior inhibition, thus enabling the bottom-up fill of high aspect ratio features, which cannot be metallized by PEG. Plating experiments of high aspect ratio features confirm the advantage provided by this class of additives. A first-order scaling model that predicts the bottom-up fill efficacy of an additive system in terms of readily measured polarization parameters and the wafer geometry is also presented.