Revealing the complexation of 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid (DPS) with cuprous ion and its contribution to Cu electrodeposition

Abstract

An accelerator is an organic additive used in Cu electrodeposition, crucial for achieving superfilling during the fabrication of Cu interconnects in microelectronics. 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid (DPS) has been proposed and investigated as a substitute for SPS. However, its acceleration mechanism associated with its interaction with Cu ions has not been intensively investigated. In this study, the interaction between DPS and Cu+ was investigated using various spectroscopic analyses, including ultraviolet-visible-nearinfrared absorption (UV-VIS-NIR), electron paramagnetic resonance (EPR), and nuclear magnetic resonance (NMR) spectroscopy. UV-VIS-NIR and EPR spectroscopy revealed that DPS forms a complex with Cu+, namely Cu(I)(DPS)2. The kinetic study on the complexation of DPS with Cu+ indicated second-order reaction characteristics. The structure of the complex was suggested using 1 H and 13 C NMR spectroscopy. Furthermore, electrochemical analyses, including cyclic voltammetry (CV) and linear sweep voltammetry (LSV), were conducted to investigate the electrochemical behaviors of the Cu(I)(DPS)2 complex, demonstrating its acceleration effect on Cu electrodeposition. These results will provide valuable insights for understanding the acceleration mechanism of DPS in Cu electrodeposition.