Wire bonding on reactive metal surfaces of a metallization of a semiconductor device by providing a protective layer
View Patent ↗In semiconductor devices having a copper-based metallization system, bond pads for wire bonding may be formed directly on copper surfaces, which may be covered by an appropriately designed protection layer to avoid unpredictable copper corrosion during the wire bond process. A thickness of the protection layer may be selected such that bonding through the layer may be accomplished, while also ensuring a desired high degree of integrity of the copper surface.
1. A method, comprising:
forming a dielectric layer stack above a metallization layer formed above a substrate of a semiconductor device, said metallization layer comprising a contact region having a copper-containing surface for receiving a bond wire;
forming an opening in said dielectric layer stack to expose a portion of said copper-containing surface;
forming a protection layer at least on said exposed portion of said copper-containing surface; and
attaching a lead wire to said exposed portion of said copper-containing surface in the presence of said protection layer.
2. The method of claim 1 , wherein forming said protection layer comprises selectively depositing a conductive material on said exposed portion of said copper-containing surface by performing an electrochemical deposition process.
3. The method of claim 2 , wherein performing said electrochemical deposition process comprises depositing at least one of a compound comprised of cobalt, tungsten, phosphorous (CoWP), a compound comprised of cobalt, tungsten, boron (CoWB), a compound comprised of nickel, molybdenum, boron (NiMoB), and a compound comprised of nickel, molybdenum, phosphorous (NiMoP).
4. The method of claim 3 , wherein performing said electrochemical deposition process comprises depositing at least one of palladium (Pd) and nickel (Ni).
5. The method of claim 1 , wherein forming said protection layer comprises depositing a conductive material above said dielectric layer stack and within said opening so as to cover said exposed portion of said copper-containing surface and removing the conductive material outside said opening.
6. The method of claim 1 , wherein attaching said lead wire to said exposed portion of said copper-containing surface comprises bonding said lead wire to said exposed portion through said protection layer.
7. The method of claim 1 , wherein attaching said lead wire to said exposed portion of said copper-containing surface comprises bonding said lead wire to said protection layer.
8. The method of claim 1 , wherein forming said protection layer comprises depositing a dielectric material on said dielectric layer stack and within said opening.
9. The method of claim 1 , wherein forming said protection layer comprises applying a wet chemical surface treatment to said exposed portion of said copper-containing surface.
10. The method of claim 9 , wherein forming said protection layer further comprises reducing surface corrosion during said wet chemical surface treatment.
11. The method of claim 9 , wherein forming said protection layer comprises forming a layer of polymer material in a plasma ambient.
12. The method of claim 11 , further comprising performing an etch process in said plasma ambient for forming said opening prior to forming said layer of polymer material.