Ultrahigh-Purity Copper and Process for Producing the Same, and Bonding Wire Comprising Ultrahigh-Purity Copper

Abstract

Provided is ultrahigh purity copper having a hardness of 40 Hv 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 1 wtppm 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 (99.999999 wt %) or higher, providing the obtained ultrahigh purity copper, and providing a bonding wire for use in a semiconductor element that can be thinned.

1 . Ultrahigh purity copper having a hardness of 40 Hv or less, and a purity of 8N or higher (provided that this excludes the gas components of O, C, N, H, S and P). 
     
     
         2 . The ultrahigh purity copper according to  claim 1 , wherein the respective elements of O, S and P as gas components are 1 wtppm or less. 
     
     
         3 . The ultrahigh purity copper according to  claim 1  or  claim 2 , wherein the recrystallization temperature is 200° C. or less. 
     
     
         4 . A bonding wire comprised of the ultrahigh purity copper according to any one of  claims 1  to  3 . 
     
     
         5 . 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. 
     
     
         6 . The manufacturing method of ultrahigh purity copper according to any one of  claims 1  to  3  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.