Rework process
AssigneeInternational Business Machines Corporation
InventorsRussell G. Berger, Jr., Albert J. Gregoritsch, Jr.
Life of this patent
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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.
Claims6
A terminal metal rework process, comprising the steps of:
- a) providing a semiconductor wafer having terminal metals thereon comprising a solder bump on layers of underlying metals, wherein said layers of underlying metals comprise a first metal layer on a second metal layer on said wafer, said wafer further comprising a permanent third aluminum metal layer, and wherein said second metal layer contacts said permanent third aluminum metal layer;
- b) selectively removing said solder bumps from said substrate with an acidic solder etchant;
- and then
- c) selectively removing said first metal layer and said second metal layer from said substrate by sideways etching said second metal layer with an etchant that does not substantially etch said first metal layer and that does not substantially damage said permanent third aluminum layer.
Dependencies are inferred from the claim text.