Method of etching metal with increased etching selectivity

摘要

A method for etching metal which can increase the metal-to-photoresist etching selectivity of a metal layer aimed to be etched with respect to a photoresist layer overlaying the metal layer. The method includes a first step of forming a cap oxide layer over the metal layer; a second step of forming a photoresist layer with a desired pattern over the cap oxide layer; a third step of conducting an ion implantation process on the photoresist layer; and a final step of conducting an etching process on the semiconductor wafer by using the photoresist layer as a mask so as to etch away exposed portions of the metal layer that are uncovered by the photoresist layer. Through experiments, it is found that the invention provides a significantly improved etching selectivity over the prior art.