Process for controlled collapse chip connection - wherein ball-limiting metallurgy is etched in the presence of lead@-tin@ solder bumps

摘要

A method is disclosed for removing metal layers from the surface of a wafer in the presence of a Pb/Sn solder bump, comprising the steps (a) removing a first metal layer (15) from the surface by exposing it to a first etchant, wherein a protective layer (18) is formed on the solder bump (17), (b) removing a second metal layer (14) from the surface of the wafer by exposing it to a second etchant, wherein at least a portion of the protective layer remains on the Pb/Sn solder bump after exposure to the second etchant, and (c) removing the protective layer from the solder bump by exposing the wafer to a third etchant.