| 摘要 |
It is intended to perform selective uniform etching of copper or a copper alloy even when mixed with another metal. There is provided a copper etchant of <= 45 mN/m surface tension and 6.0 to 8.5 pH value containing at least ammonium oxalate, hydrogen peroxide and a surfactant. The ammonium oxalate functions as a complexing agent for dissolving copper in the form of a copper complex. The hydrogen peroxide functions as an oxidant for oxidizing a copper surface. The addition of the surfactant lowers the surface tension of the etchant to <= 45 mN/m. As a result, substrate surface wetting and etchant permeation into high-aspect portions of a substrate structure can be enhanced, and in the co-presence of a metal with high conductivity for wiring or electrode, copper or copper alloys can be etched uniformly and selectively.
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