In Situ Wide-Frequency Surface-Enhanced Infrared Absorption Spectroscopy Enables One to Decipher the Interfacial Structure of a Cu Plating Additive
Zijie Mao, Yicai Wu, Xian‐Yin Ma, Li Zheng, Xia‐Guang Zhang, Wen–Bin Cai
Abstract
In situ spectroscopic characterization of the interfacial structure of an organic additive at a Cu electrode is essential for a mechanistic understanding of Cu superfilling at the molecular level. In this work, we demonstrate wide-frequency attenuated total reflection surface-enhanced infrared absorption spectroscopy (wf-ATR-SEIRAS) to elucidate the dissociative adsorption of bis(sodium sulfopropyl)-disulfide (a typical accelerator) on a Cu electrode in conjunction with the electrochemical quartz crystal microbalance measurement and modeling calculations. The wf-ATR-SEIRAS clearly identifies the peaks featuring the sulfonate and methylene groups as well as the C–Ssulfonate and C–Sthiol vibrations of the adsorbate. Analysis of relative peak intensities from 1100 to 650 cm–1 reveals a more tilted alkyl chain axis for the thiolate on Cu than that on Au, which is supported by comparative density functional theory calculations. This work opens a new avenue for the wf-ATR-SEIRAS to study interfacial structures of electroplating additives related to advanced microelectronics manufacture.