| abstract |
A method for preparing a copper pad surface for electrical connection that has superior diffusion barrier and adhesion properties is provided. In the method, a copper pad surface is first provided that has been cleaned by an acid solution, a protection layer of a phosphorus or boron-containing metal alloy is then deposited on the copper pad surface, and then an adhesion layer of a noble metal is deposited on top of the protection layer. The protection layer may be a single layer, or two or more layers intimately joined together formed of a phosphorus or boron-containing metal alloy such as Ni-P, Co-P, Co-W-P, Co-Sn-P, Ni-W-P, Co-B, Ni-B, Co-Sn-B, Co-W-B and Ni-W-B to a thickness between about 1,000 Å and about 10,000 Å. The adhesion layer can be formed of a noble metal such as Au, Pt, Pd and Ag to a thickness between about 500 Å and about 4,000 Å. |