Superfilling evolution in Cu electrodeposition - Dependence on the aging time of the accelerator

초록

Interesting phenomena were observed during an investigation on the accelerating effects of 3-mercapto-1-propane sulfonic acid (MPSA), i. e., different aging times of MPSA result in different filling profiles. When MPSA was added to the electrolyte immediately before electrodeposition, subconformal deposits appeared, whereas MPSA aged over 12 h enabled superfilling. From UV-visible analysis, over 99% MPSA was converted to bis(3-sulfopropyl)disulfide (SPS) within 12 h through the reaction with Cu2+, which means that SPS was, in terms of "visible'' superfilling, the real accelerator. This arose from the fact that SPS experienced adsorption first, while MPSA underwent Cu2+ reduction first at the trench entrance. (C) 2004 The Electrochemical Society.

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