In-Situ Ellipsometric Study of the Competitive Adsorption of PEG-/CI-/(SPS/MPS) on Cu
Marlon L. Walker, Lee J. Richter, Thomas P. Moffat
The adsorption of Cu electrodeposition accelerating agents SPS and MPS on evaporated Cu thin films was examined in-situ using spectroscopic ellipsometry under quiescent conditions. Both the thiol (MPS) and disulfide (SPS) resulted in definitive changes in the optical response of the interface, indicative of irreversible chemisorption. The optical responses of the two additives were different, however, suggesting a difference in the adsorbed states. Upon thiol or disulfide adsorption, the inhibition of the specific adsorption of PEG in the presence of Cl- is demonstrated. Pre-adsorbed Cl-/PEG layers hinder SPS adsorption to a greater extent than MPS adsorption; however, these layers are disrupted upon the adsorption of either organosulfur additive..