Structural effect of inhibitors on adsorption and desorption behaviors during copper electroplating for through-silicon vias

Abstract

Cu extreme superfilling of through-silicon vias (TSV) in advanced interconnects is recently achieved by poloxamine Tetronic 701 (Te701) as a single inhibitor. However, the mechanism of Te701 during Cu deposition is still unclear and need further exploration. In this work, three different inhibitors, Te701, poly(ethylene glycol) (PEG) and poloxamer Pluronic F-68 (F68), were studied for their effects during Cu electrodeposition. The electrochemical results show that Te701 exhibited a stronger inhibiting capacity than PEG and F68 at higher potential and performed better at the increased concentration. The morphologies of deposited Cu on planar substrates exhibited that PEG or F68 generated flat Cu films, while Te701 led to the growth of local abnormal nodules. Next, an adsorption-desorption model was proposed to explain the strong inhibiting capacity of Te701 owing to its inconsistent desorption of polyoxypropylene blocks and protonated ethylenediamine groups. Finally, the excellent inhibiting effect of Te701 at the via mouth promoted the achievement of extreme superfilling, which can be explained by the electrochemical results. This work provides a new molecular-level perspective to understand the extreme superfilling in TSVs with a single inhibitor and is of theoretical significance for inhibitor selection.