SEIRAS Study of Chloride Mediated Polyether Adsorption on Cu

Published

August 31, 2018

Author(s)

Thomas P. Moffat, Daniel Josell, Lee J. Richter

Abstract

Surface enhanced infrared absorption spectroscopy (SEIRAS) was used to examine the co- adsorption of a selection of polyethers with Cl- under conditions relevant to superconformal Cu electrodeposition in CuSO4-H2SO4 electrolytes. In 0.1 mol/L H2SO4 a potential dependent mixed SO42--H3O+/H2O layer forms on weakly textured (111) Cu thin film surfaces. With the addition of 1 mmol/L NaCl the SO42--H3O+/H2O adlayer is displaced and rapidly replaced by an ordered halide layer that disrupts the adjacent solvent network leading to an increase in non-hydrogen bonded water that makes the interface more hydrophobic. The altered wetting behavior facilitates co- adsorption of polyethers, such as poly(ethylene glycols), polyoxamers, or polyoxamines. Interfacial water is displaced by co-adsorption of the hydrophobic polymer segments on the Cl- terminated surface while the hydrophilic ether oxygens are available for hydrogen bond formation with the solvent. The combined polyether-Cl- layer serves as an effective suppressor of the Cu electrodeposition reaction by limiting access of Cu2+aq to the underlying metal surface. This insight differs from previous efforts that suggest polymer binding is mediated by Cu+ species.

Citation

Journal of Physical Chemistry C

Pub Type

Journals

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Keywords

copper, superconformal, superfilling, polyethylene glycol, SEIRAS, FT-IR, suppressor, inhibitor

Citation

Moffat, T. , Josell, D. and Richter, L. (2018), SEIRAS Study of Chloride Mediated Polyether Adsorption on Cu, Journal of Physical Chemistry C, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926260 (Accessed April 18, 2024)