Erratum: "Copper electroplating for future ultralarge scale integration interconnection" [J.

Interesting phenomena were observed during an investigation on the accelerating effects of 3-mercapto-1-propane sulfonic acid ͑MPSA͒, 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 bis͑3-sulfopropyl͒disulfide ͑SPS͒ within 12 h through the reaction with Cu 2ϩ , 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 Cu 2ϩ reduction first at the trench entrance.

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The synthesis of metal nanostructures usually requires a capping agent that is generally thought to cause anisotropic growth by blocking the addition of atoms to specific crystal facets. This work uses a series of electrochemical measurements with a quartz crystal microbalance and single-crystal electrodes to elucidate the facet-selective chemistry occurring in the synthesis of Cu nanowires. Contrary to prevailing hypotheses, ethylenediamine, a so-called capping agent in the synthesis of Cu nanowires, causes anisotropic growth by increasing the rate of atomic addition to (111) facets at the end of a growing nanowire relative to (100) facets on the sides of a nanowire. Ethylenediamine increases the reduction rate of Cu(OH) on a Cu(111) surface relative to Cu(100) by selectively inhibiting the formation of Cu oxide on Cu(111). This work demonstrates how studying facet-selective electrochemistry can improve the understanding of the processes by which atoms assemble to form anisotropic metal nanostructures.

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