TY - JOUR
T1 - Suppression of copper electrodeposition by PEG in methanesulfonic acid electrolytes
AU - Rooney, Ryan T.
AU - Jha, Himendra
AU - Rohde, Dirk
AU - Schmidt, Ralf
AU - Gewirth, Andrew A.
N1 - Funding Information:
We thank Atotech for funding this Research. The authors also thank Dr. Bruno Nicolau for discussions regarding the MSA behavior and Minjeong Shin for help processing SER spectra.
Publisher Copyright:
© The Author(s) 2019.
PY - 2019
Y1 - 2019
N2 - 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.
AB - 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.
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U2 - 10.1149/2.0171913jes
DO - 10.1149/2.0171913jes
M3 - Article
AN - SCOPUS:85073690349
SN - 0013-4651
VL - 166
SP - D551-D558
JO - Journal of the Electrochemical Society
JF - Journal of the Electrochemical Society
IS - 13
ER -