The Degradation Behavior of Brightener on Dimensionally Stable Anodes during the Copper Electrodeposition

This study shows the firstwork that in the copper electroplating bath containing brighteners, the degradation and lifetime of brighteners are mainly determined by the mixed metal oxide (MMO) coating on the anode. We demonstrate that the depolarizing ability and lifetime of bis-3-sulfopropyl-disulfide (SPS), a typical brightener in the copper electroplating bath, are strongly affected by the oxidative activity of the anode. Here, the commercially available IrO2-based and Ta2O5-based dimensionally stable anodes (DSA) are employed in the Cu plating, and the oxidation rate of SPS during the deposition is analyzed. The results reveal the prolonged depolarizing ability and lifetime of SPS in the plating bath when the relatively inert anode, Ta2O5-DSA, is used. The degradation rate of brighteners can be quantified by the voltammetric stripping method and consequently, the variation in the brighteners activity during electrodeposition can be precisely tracked to ensure their functions. Moreover, the inert anode is highly recommended to prolong the function and lifetime of SPS, which is cost-effective and beneficial for circumventing the bath aging issue. (C) 2019 The Electrochemical Society.