Electrochemical analysis of cathode in TSV copper electroplating

In TSV copper electroplating, the most important is to form the “bottom up” deposition. In order to achieve this kind of super-filling, additive in the electroplating bath need to play its own role at the respective position. Accelerator adsorb at the bottom of the via to accelerate the deposition of copper while suppressor mostly adsorb at the top of the via to inhibit the deposition. Therefore, vias could be supper-filled without any void. In this paper, bis(3-sulfopropyl) disulfide (SPS) and polyethylene glycol (PEG) were used as accelerator and suppressor respectively. The supper-filling mechanism and the competitive adsorption of SPS and PEG were being researched by means of linear sweep voltammetry (LSV) and cyclic voltammogram (CV). The electrochemical analysis and the experimental plating are closely related.