ULTRAHIGH-PURITY COPPER AND PROCESS FOR PRODUCING THE SAME, AND BONDING WIRE COMPRISING ULTRAHIGH-PURITY COPPER

摘要

Provided is ultrahigh purity copper having a hardness of 40Hv or less, and a purity of 8N or higher (provided that this excludes the gas components of O, C, N, H, S and P). With this ultrahigh purity copper, the respective elements of O, S and P as gas components are 1wtppm or less. Also provided is a manufacturing method of ultrahigh purity copper based on two-step electrolysis using an electrolytic solution comprised of copper nitrate solution, including the procedures of adding hydrochloric acid in an electrolytic solution comprised of copper nitrate solution; circulating the electrolytic solution; and performing two-step electrolysis while eliminating impurities with a filter upon temporarily setting the circulating electrolytic solution to a temperature of 10°C or less. The present invention provides a copper material that is compatible with the thinning (wire drawing) of the above, and is capable of efficiently manufacturing ultrahigh purity copper having a purity of 8N (99.999999wt%) or higher, providing the obtained ultrahigh purity copper, and providing a bonding wire for use in a semiconductor element that can be thinned.