Coated bonding wire and methods for bonding using same
A semiconductor device includes a bond formed on a bond pad. The bond is formed of a wire that includes a central core of conductive metal, a first coating over the central core of conductive metal that is more chemically active than the conductive metal, and a second coating over the central core of conductive metal that is less chemically active than the central core of conductive metal.
1. A semiconductor device comprising:
a packaging mold compound;
a wire bond embedded in the packaging mold compound, wherein
a wire of the wire bond includes a central core of electrically conductive material, a sacrificial coating over the central core of electrically conductive material, and a second coating over the central core of conductive material, and
the central core of electrically conductive material includes at least one of a group consisting of copper and silver, and the sacrificial coating is formed of a material that has a lower reduction potential than the central core of electrically conductive material and the second coating, and the second coating has a higher reduction potential than the central core of electrically conductive material.
2. The device of claim 1 , wherein an interface between the central core and a bond pad is devoid of the sacrificial coating, and the second coating is between the bond pad and the central core of electrically conductive material.
3. The device of claim 2 , wherein the sacrificial coating is in direct contact with the central core of electrically conductive material and the second coating is in direct contact with the sacrificial coating.
4. The device of claim 1 , wherein a thickness of the sacrificial coating is between 0.05 and 0.20 micrometers.
5. The device of claim 1 , wherein the bond is one of a group consisting of a ball bond, a wedge bond, and a stitch bond.
6. The device of claim 1 , wherein the sacrificial coating includes one of group consisting of zinc, aluminum, and magnesium.
7. The device of claim 1 , wherein the second coating includes palladium.
8. A semiconductor device comprising:
a packaging mold compound; and
a wire bond embedded in the packaging mold compound, wherein a wire of the wire bond includes:
a central core of electrically conductive material,
a sacrificial coating over the central core of electrically conductive material,
a second coating over the central core of conductive material, and
a third coating, and
the sacrificial coating is formed of a material that has a lower reduction potential than the central core of electrically conductive material and the second coating, and the second coating has a higher reduction potential than the central core of electrically conductive material, and the second coating is in direct contact with the central core of electrically conductive material, and the sacrificial coating is between the second coating and the third coating.
9. The device of claim 8 , wherein an interface between the central core and a bond pad is devoid of the sacrificial coating, and the second coating is between the bond pad and the central core of electrically conductive material.
10. The device of claim 9 , wherein the sacrificial coating is in direct contact with the central core of electrically conductive material and the second coating is in direct contact with the sacrificial coating.
11. The device of claim 8 , wherein a thickness of the sacrificial coating is between 0.05 and 0.20 micrometers.
12. The device of claim 8 , wherein the bond is one of a group consisting of a ball bond, a wedge bond, and a stitch bond.
13. The device of claim 8 , wherein the sacrificial coating includes one of group consisting of zinc, aluminum, and magnesium.
14. The device of claim 8 , wherein the second coating includes palladium.
15. A semiconductor device comprising:
a packaging mold compound; and
a wire bond embedded in the packaging mold compound, wherein a wire of the wire bond includes:
a central core of electrically conductive material, a sacrificial coating over the central core of electrically conductive material, a second coating over the central core of conductive material, and a third coating, and
the sacrificial coating is formed of a material that has a lower reduction potential than the central core of electrically conductive material and the second coating, and the second and third coatings have a higher reduction potential than the central core of electrically conductive material, and the second coating is in direct contact with the central core of electrically conductive material, and the sacrificial coating is between the second coating and the third coating.
16. The device of claim 15 , wherein an interface between the central core and a bond pad is devoid of the sacrificial coating, and the second coating is between the bond pad and the central core of electrically conductive material.
17. The device of claim 15 , wherein the bond is one of a group consisting of a ball bond, a wedge bond, and a stitch bond.
18. The device of claim 15 , wherein the central core of electrically conductive material includes at least one of a group consisting of copper and silver.
19. The device of claim 15 , wherein the second coating includes palladium.