Abstract
We investigate the suppression behavior of poly(ethylene glycol) (PEG) in methanesulfonic acid (MSA) Cu plating baths using electrochemical methods, normal Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), and electrochemical quartz crystal microbalance (QCM) measurements. Suppression of Cu electrodeposition by PEG in H2SO4 electrolytes only occurs in the presence of Cl−, whereas Cl− is not required in MSA electrolytes. SERS measurements of MSA electrolytes without PEG at a Cu surface show MSA molecules undergo a re-orientation at ca. −0.15 V vs. Ag/AgCl, as evidenced by potential-dependent symmetry changes. The re-orientation of MSA in MSA + PEG electrolyte does not occur until −0.3 V vs. Ag/AgCl. At potentials negative of −0.3 V, MSA re-orients and PEG leaves the surface, in coordination with onset of Cu reduction current, suggesting the suppression interaction of PEG at a Cu surface is facilitated by MSA. QCM measurements demonstrate a similar departure of PEG mass at potentials negative of the MSA re-orientation.
Original language | English (US) |
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Pages (from-to) | D551-D558 |
Journal | Journal of the Electrochemical Society |
Volume | 166 |
Issue number | 13 |
DOIs | |
State | Published - 2019 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Electrochemistry
- Materials Chemistry