Abstract: A semiconductor wafer rework process sideways etches an underlying layer of metal to remove a difficult to etch upper layer of metal without substantially etching that upper layer and without damaging permanent layers of the wafer. If the underlying layer of metal is TiW and the permanent layer is aluminum, the TiW layer can be sideways etched with a hydrogen peroxide and ammonium hydroxide solution that does not damage aluminum lines that are permanently on the wafer. Thus, difficult to remove intermetallic layers, such as tin-copper or chrome-copper, that are located on an underlying layer of TiW, can be successfully removed without danger of damaging permanent aluminum metallization of the wafer.