Copper interconnect electroplating is one of the core technologies for the manufacture of high-end electronic devices including but not limited to chips. To promote the development of advanced copper interconnect process, it is necessary to clarify the mechanisms of copper electroplating additives. Herein, we provide a brief overview of the research progress on the interfacial structures and mechanisms of the three types of additives (accelerator, suppressor and leveler) in copper sulfate plating baths from a methodological perspective. Besides, the advantages and limitations of different research methods are discussed and the scientific issues related to the Damascene copper electroplating are summarized, to afford a hint for the further research and development of the additives in advanced chip fabrication.

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.