Redistribution metal and under bump metal interconnect structures and method

1. An integrated circuit die, comprising:

a metal layer;

a first passivation layer disposed above the metal layer;

a redistribution layer disposed above the first passivation layer, wherein the redistribution layer is planar with a bottom surface in direct contact with the first passivation layer; and

a redistribution layer plug disposed in a via through the first passivation layer, wherein a top surface of the redistribution layer plug is substantially in-plane with the bottom surface of the redistribution layer, and a bottom surface of the redistribution layer plug is substantially in-plane with the metal layer, wherein material of the redistribution layer is not within the via; and

an under bump metallization layer coupled to the redistribution layer above the first passivation layer at a lateral distance from the redistribution layer plug.

2. The integrated circuit die of claim 1 , wherein the redistribution layer plug comprises tungsten, titanium, titanium nitride, titanium-tungsten, or nickel silicide.

3. The integrated circuit die of claim 2 , wherein the under bump metallization layer is connected to the metal layer at a location directly below a bump structure attached to the under bump metallization layer.

4. The integrated circuit die of claim 1 , wherein the redistribution layer plug comprises copper.

5. The integrated circuit die of claim 4 , wherein the top surface comprises tungsten, titanium, or tantalum.

6. The integrated circuit die of claim 1 , wherein the under bump metallization layer is coupled to the redistribution layer through a polyimide layer, the redistribution layer comprising, copper, aluminum, gold or mixtures thereof.

7. An integrated circuit die, comprising:

a metal layer;

a first passivation layer disposed above the metal layer;

a conductive layer disposed above the first passivation layer;

a polyimide layer disposed above the conductive layer; and

an under bump metallization layer extended to the metal layer through the polyimide layer, the conductive layer, and the first passivation layer, wherein the under bump metallization layer directly contacts the metal layer and the conductive layer.

8. The integrated circuit die of claim 7 , wherein the under bump metallization layer is provided through a first hole in the polyimide layer, a second hole in the conductive layer, and a third hole in the first passivation layer, the first hole being larger than the second hole and the second hole at a bottom being substantially the same size as the third hole at a top.

9. The integrated circuit die of claim 7 , wherein the under bump metallization layer is provided through a first hole in the polyimide layer, a second hole in the conductive layer, and a third hole in the first passivation layer, the first hole being larger than the second hole and the second hold being larger than the third hole.

10. The integrated circuit die of claim 7 , further comprising a second passivation layer above the first passivation layer and at least partially above the conductive layer.

11. The integrated circuit die of claim 7 wherein the under bump metallization layer comprises copper.

12. An integrated circuit die, comprising:

a metal layer;

a barrier layer above the metal layer;

a first passivation layer disposed above the barrier layer;

a redistribution layer disposed above the first passivation layer, wherein the redistribution layer does not contact the metal layer; and

an under bump metallization layer plug coupled to the metal layer and disposed in a via that is provided through the first passivation layer, the redistribution layer, and the barrier layer, wherein a top surface of the redistribution layer plug is disposed above a top surface of the redistribution layer.

13. The integrated circuit die of claim 12 , further comprising:

an under bump metallization layer coupled to the redistribution layer above the first passivation layer at a distance from the redistribution layer plug, wherein the under bump metallization layer comprises a material, the material being the same material as the under bump metallization layer plug.

14. The integrated circuit die of claim 12 , wherein the under bump metallization layer is connected to the metal layer without aluminum in the under bump metallization layer plug.

15. The integrated circuit die of claim 13 , wherein the under bump metallization layer plug comprises copper.

16. The integrated circuit die of claim 13 , further comprising:

a polyimide layer disposed above the redistribution layer, wherein the top surface of the under bump metallization layer plug extends above the polyimide layer and the redistribution layer comprises aluminum.

17. An integrated circuit die, comprising:

a metal layer;

a first passivation layer disposed above the metal layer;

a first polyimide layer disposed above the first a passivation layer; and

an under bump metallization layer coupled to the metal layer through the first polyimide layer, wherein the under bump metallization layer comprises at least one conductor extending across a top surface of the first polyimide layer and away from an area for a solder bump or pillar for the integrated circuit die, wherein the under bump metallization layer is directly connected between the solder bump or pillar and the metal layer.

18. The integrated circuit die of claim 17 , further comprising a second polyimide layer having a top surface disposed directly above the under bump metallization layer and the conductor.

19. The integrated circuit die of claim 17 , wherein the under bump metallization layer and the conductor comprise copper.

20. The integrated circuit die of claim 17 , wherein the conductor is not covered by a dielectric.