Method for chemical etch control of noble metals in the presence of less noble metals

摘要

A method for preparing a bonding pad on an integrated circuit wafer by the steps of depositing a conductive seed layer (104) on the bonding pad; depositing a metal layer (301, 302, and 303) over a portion of the conductive seed layer; and immersing the wafer in an etchant solution (501) to remove the portion of the seed layer not covered by the metal layer. The etchant solution contains a chelating agent that bonds ions from the seed layer. When the seed layer is copper or a refractory metal, and the metal layer is gold or palladium, the preferred chelating agent is selected from, but is not limited to, but is not limited to, the families of ethylenediaminetetraacetic acids (EDTA), 8-hydroxy-quinolines, including 8-hydroxy-quinoline-5-sulfonic acid, porphyrins, and phthalocyanines.