Selective etch of TiW for capture pad formation
AssigneeInternational Business Machines Corporation
InventorsCarla A. Bailey, Camille P. Bowne, Krystyna W. Semkow
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Abstract
A chemical etchant containing hydrogen peroxide and phosphate ions at a controlled pH is provided for selectively etching metals in the presence of one or more metals not to be etched. The etchant is useful in the fabrication of semiconductor components particularly for forming capture pads where TiW is used as a barrier layer for a copper, copper/nickel pad, or copper/nickel alloy pad. A commercial hydrogen peroxide solution is preferred to which has been added phosphoric acid as a source of phosphate ions and KOH as the pH adjuster.
Claims8
A chemical etchant for etching titanium-tungsten alloys in microelectronics fabrication of capture pads for C4 solder bumps in the presence of one or more metals not to be etched, the etchant consisting essentially of:
- an aqueous solution maintained at a temperature between about 25° C. and 60° C. comprising;
- about 5% to 12% by weight of solution of H2O2;
- about 0.06% to 0.6% by weight of solution of phosphate ions;
- an amount of a pH adjusting material to provide the aqueous solution with a pH of about 4-6;
- and
- the balance H2O,
- wherein said aqueous solution does not etch one or more metals selected from the group consisting of copper, copper/nickel, and copper/nickel alloys.
Dependencies are inferred from the claim text.