Production Method of High Purity Copper for Semiconductor Use and Evaluation of the Quality (Report I)(Materials, Metallurgy & Weldability)

概要

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The new refining process to remove infinitesimal sulfur (S) impurity contained in twofold electrolytic refined copper has been developed using sulfide forming method followed by zone refining. Various dopant materials were examined thermodynamically and experimentally for eliminating S element in extremely small quantity and sweeping out themselves after zone refining. Lanthanum element was found out to be optimal as a result of the experiment for this purpose. Residual S content in copper has been reduced to less than 0.1 wt.ppm after this refining process and thus, extremely high purity copper which hardly contains not only heavy metal elements such as silver, iron, lead, tellurium, selenium, arsenic, antimony, bismuth but also S has been obtained. The developed copper has been expected to be used for semiconductor application because of much higher purity than oxygen free copper available in market. This paper describes the production method of high purity copper for semiconductor use together with desulfurization mechanism as a first report.
大阪大学の論文