Solder bump with inner core pillar in semiconductor package

1. An electrical interconnect within a semiconductor package, consisting of:

a substrate having a plurality of active devices formed thereon;

a contact pad formed on the substrate in electrical contact with the plurality of active devices;

a first insulation layer formed over the substrate;

a second insulation layer formed over the first insulation layer;

a first barrier layer formed over the contact pad and the first and second insulation layers;

an adhesion layer formed over the first barrier layer;

a seed layer formed over the adhesion layer;

a single cylindrical inner core pillar including a hollow interior centered over and formed within a footprint of the contact pad;

a second barrier layer and a wetting layer formed over the single cylindrical inner core pillar and the hollow interior; and

a spherical bump formed around the second barrier layer, the wetting layer, and the single cylindrical inner core pillar, wherein a footprint of the spherical bump encompasses the footprint of the contact pad, and the spherical bump is electrically connected to the contact pad.

2. The electrical interconnect of claim 1 , wherein the single cylindrical inner core pillar is made of copper, nickel, or other metal.

3. The electrical interconnect of claim 1 , wherein the single cylindrical inner core pillar extends into the spherical bump at least two-thirds of a height of the spherical bump.

4. The electrical interconnect of claim 1 , wherein the single cylindrical inner core pillar has a width 40-60% of a width of a spherical bump diameter.

5. An electrical interconnect within a semiconductor package, consisting of:

a substrate having a plurality of active devices formed thereon;

a contact pad formed on the substrate in electrical contact with the plurality of active devices;

an insulation layer formed over the substrate;

an under bump metallization (UBM) formed over the contact pad and the insulation layer;

a cylindrical inner core pillar including a hollow interior centered over and formed within a footprint of the contact pad;

a conductive layer formed over the cylindrical inner core pillar and the hollow interior; and

a spherical bump formed around the conductive layer, the cylindrical inner core pillar, and electrically connected to the contact pad.

6. The electrical interconnect of claim 5 , wherein the UBM includes an adhesion layer, barrier layer, and seed layer.

7. The electrical interconnect of claim 5 , wherein the cylindrical inner core pillar is made of copper, nickel, or other metal.

8. The electrical interconnect of claim 5 , wherein the conductive layer includes a barrier layer and a wetting layer.

9. The electrical interconnect of claim 5 , wherein the cylindrical inner core pillar extends into the spherical bump at least two-thirds of a height of the spherical bump.

10. An electrical interconnect within a semiconductor package, consisting essentially of:

a substrate having a plurality of active devices formed thereon;

a contact pad formed on the substrate in electrical contact with the plurality of active devices;

an insulation layer formed over the substrate;

an under bump metallization (UBM) formed over the contact pad and the insulation layer;

an inner core pillar including a hollow interior formed within a footprint of the contact pad;

a first barrier layer and a wetting layer formed over the inner core pillar; and

a spherical bump formed around the first barrier layer, the wetting layer, and the inner core pillar, wherein the spherical bump is electrically connected to the contact pad.

11. The electrical interconnect of claim 10 , wherein the UBM includes an adhesion layer, a second barrier layer, and a seed layer.

12. The electrical interconnect of claim 10 , wherein the inner core pillar has a form factor selected from the group consisting of rectangular, cylindrical, and toroidal.

13. The electrical interconnect of claim 10 , wherein the first barrier layer and the wetting layer are formed within the hollow interior of the inner core pillar.

14. The electrical interconnect of claim 10 , wherein the inner core pillar is made of copper, nickel, or other metal.

15. The electrical interconnect of claim 10 , wherein the inner core pillar extends into the spherical bump at least two-thirds of a height of the spherical bump.

16. The electrical interconnect of claim 10 , wherein the inner core pillar is centered over the footprint of the contact pad.

17. An electrical interconnect within a semiconductor package, consisting essentially of:

a substrate having a plurality of active devices formed thereon;

a contact pad formed over the substrate in electrical contact with the plurality of active devices;

an insulation layer formed over the substrate;

an under bump metallization (UBM) formed over the contact pad and the insulation layer;

an inner core pillar including a hollow interior formed within a footprint of the contact pad;

a conductive layer formed over the inner core pillar; and

a rounded bump formed around the conductive layer and the inner core pillar, wherein the rounded bump is electrically connected to the contact pad.

18. The electrical interconnect of claim 17 , wherein the UBM includes an adhesion layer, a barrier layer, and a seed layer.

19. The electrical interconnect of claim 17 , wherein the conductive layer includes a barrier layer and wetting layer.

20. The electrical interconnect of claim 17 , wherein the inner core pillar has a form factor selected from the group consisting of rectangular, cylindrical, and toroidal.

21. The electrical interconnect of claim 17 , wherein the conductive layer is formed within the hollow interior of the inner core pillar.

22. The electrical interconnect of claim 17 , wherein the inner core pillar is made of copper, nickel, or other metal.

23. The electrical interconnect of claim 17 , wherein the inner core pillar extends into the rounded bump at least two-thirds of a height of the rounded bump.