Granted Patent B2

US 6,930,032 · App. 10/145,500 · Granted Aug 16, 2005

Abstract

Claims (30)

1. A method for creating an under bump metallization, comprising the steps of:

providing a die having a die pad disposed thereon;

forming a stress compensation layer over the die pad, said stress compensation layer having a thickness within the range of about 10 to about 100 microns and comprising a first photo-definable polymer;

masking and exposing the stress compensation layer to create an aperture therein which exposes the die pad;

forming a bus metal layer over the stress compensation layer and within the aperture;

forming a layer of a second photo-definable polymer over the bus metal layer;

masking and exposing the second polymer to create a first region in which the bus metal layer is exposed and a second region in which the bus metal layer is covered by the second polymer, the first region including at least a portion of the aperture; and

forming an under bump metallization on the bus metal layer in the first region;

wherein the under bump metallization has a thickness of at least about 20 microns as measured in the center of the aperture along a line orthogonal to the die pad.

2. The method of claim 1 , wherein the first polymer is an epoxy.

3. The method of claim 2 , wherein the epoxy contains an inorganic filler.

4. The method of claim 3 , wherein the filler is selected from the group consisting of borosilicate glass, quartz, silica, and glass beads.

5. The method of claim 1 , wherein the second polymer is a photoresist.

6. The method of claim 1 , wherein the under bump metallization is deposited via an electroplating process.

7. The method of claim 6 , wherein the under bump metallization comprises copper.

8. The method of claim 1 , wherein said under bump metallization includes a receptacle for receiving a solder ball.

9. The method of claim 1 , wherein the under bump metallization includes a bowl-shaped portion.

10. The method of claim 1 , wherein the under bump metallization has a thickness within the range of about 45 microns to about 75 microns as measured in the center of the aperture along a line orthogonal to the die pad.

11. The method of claim 1 , wherein the bus metal layer comprises TiW and the under bump metallization comprises Cu.

12. A method for creating an under bump metallization, comprising the steps of:

providing a die having a die pad disposed thereon;

forming a stress compensation layer on or over the die pad, said stress compensation layer comprising a photo-definable polymer and having a thickness within the range of about 10 to about 100 microns;

masking and exposing the stress-compensation layer to create an aperture having at least a portion of a bus metallization layer exposed therein; and

forming an under bump metallization on the exposed portion of the bus metallization layer;

wherein the under bump metallization has a thickness of at least about 20 microns as measured in the center of the aperture along a line orthogonal to the die pad.

13. The method of claim 12 , wherein the thickness of the stress compensation layer is within the range of about 20 to about 60 microns.

14. The method of claim 12 , wherein the thickness of the stress compensation layer is within the range of about 30 to about 50 microns.

15. The method of claim 12 , wherein the under bump metallization has a thickness within the range of about 45 microns to about 75 microns as measured in the center of the aperture along a line orthogonal to the die pad.

16. The method of claim 12 , wherein the shape of the under bump metallization is determined primarily by the stress compensation layer.

17. The method of claim 1 , wherein the shape of the under bump metallization is determined primarily by the stress compensation layer.

Assignments (22)