Selective etch of TiW for capture pad formation

摘要

A chemical etchant containing hydrogen peroxide and phosphate ions at a controlled pH is provided for selectively etching metals in the presence of one or more metals not to be etched. The etchant is useful in the fabrication of semiconductor components particularly for forming capture pads where TiW is used as a barrier layer for a copper, copper/nickel pad, or copper/nickel alloy pad. A commercial hydrogen peroxide solution is preferred to which has been added phosphoric acid as a source of phosphate ions and KOH as the pH adjuster.