The adsorption of PEG-Cl on a.) air-oxidized Ru, b.) reduced or activated Ru and c.) underpotential deposited (upd) Cu on activated Ru was examined in-situ using spectroscopic ellipsometry. In the absence of Cl- ion, PEG adsorption was minimal at all potentials and on all surfaces characterized in this study. On activated Ru, the addition of Cl- ion resulted in PEG coadsorption. At potentials relevant to Cu upd, a three-component PEG-Cl--Cu layer forms independent of the order of additive addition to the electrolyte. The PEG-Cl--Cu upd overlayer provides inhibition of subsequent Cu overpotential deposition. At potentials positive of Cu upd, a monolayer oxide film forms that inhibits PEG adsorption even in the presence of Cl-. Ru oxidation exerts a strong effect on the adsorption of additives that are directly relevant to the nucleation and growth of electrodeposited Cu.
Citation: Journal of the Electrochemical Society
Issue: No. 4
Pub Type: Journals
coadsorption under potential deposition, Cu electrodeposition, Cu upd, PEG-C1, Ru Barrier material, spectroscopic ellipsomety, superfilling