Adhesion between post-passivation interconnect structure and polymer
An embodiment integrated circuit structure includes a substrate, a metal pad over the substrate, a post-passivation interconnect (PPI) structure over the substrate and electronically connected to the metal pad, a thin oxide film layer directly over a top surface of the PPI structure, and a polymer layer over the thin oxide film layer and PPI structure.
1. An integrated circuit structure comprising:
a substrate;
a metal pad over the substrate;
a passivation layer over the substrate and covering an edge portion of the metal pad;
a post-passivation interconnect (PPI) structure over the passivation layer and electronically connected to the metal pad;
a thin oxide film layer directly over a top surface of the PPI structure; and
a polymer layer over the thin oxide film layer and PPI structure.
2. The integrated circuit structure of claim 1 , wherein the thin oxide film layer has a thickness greater than about ten nanometers.
3. The integrated circuit structure of claim 1 , wherein the thin oxide film layer has a thickness less than about two hundred nanometers.
4. The integrated circuit structure of claim 1 , wherein the polymer layer has a thickness of about five to ten micrometers.
5. The integrated circuit structure of claim 1 , wherein the PPI structure comprises copper, and the thin oxide film layer comprises copper oxide.
6. The integrated circuit structure of claim 1 , wherein the polymer layer is selected from a group consisting of polyimide (PI), polybenzoxazole (PBO), benzocyclobuten (BCB), epoxy, silicone, acrylates, nano-filled pheno resin, siloxane, fluorinated polymer, polynorbornene, and combinations thereof.
7. The integrated circuit structure of claim 1 , further comprising:
an under bump metallurgy (UBM) extending into an opening in the polymer layer and the thin oxide film layer, wherein the UBM is electrically connected to the PPI structure; and
a bond ball on the UBM.
8. An integrated circuit structure comprising:
a first die, wherein the first die comprises:
a metal pad at a top surface of the first die; and
a passivation layer covering an edge portion of the metal pad;
a redistribution layer (RDL) structure over the first die, wherein the RDL structure is electrically connected to the metal pad;
a thin oxide film layer over a top surface of the RDL structure;
a polymer layer over the thin oxide film layer and the RDL structure;
an under bump metallurgy (UBM) over the polymer layer and electrically connected the RDL structure; and
a conductive bump on the UBM.
9. The integrated circuit structure of claim 8 , wherein the thin oxide film layer has a thickness greater than about ten nanometers.
10. The integrated circuit structure of claim 8 , wherein the polymer layer is selected from a group consisting of polyimide (PI), polybenzoxazole (PBO), benzocyclobuten (BCB), epoxy, silicone, acrylates, nano-filled pheno resin, siloxane, fluorinated polymer, polynorbornene, and combinations thereof.
11. The integrated circuit structure of claim 8 , wherein the RDL structure comprises a metallic material, and the thin oxide film layer comprises an oxide of the metallic material.
12. The integrated circuit structure of claim 8 , further comprising a molding compound separating the first die from a second die in the integrated circuit structure.
13. The integrated circuit of claim 8 , wherein the RDL structure comprises one or more RDL lines and RDL pads.
14. A method for forming an integrated circuit structure comprising:
forming a post-passivation interconnect (PPI) structure over a substrate, wherein the substrate comprises a metal pad and the PPI structure is electrically connected to the metal pad;
oxidizing a top surface of the PPI structure; and
forming a polymer layer over the PPI structure.
15. The method of claim 14 , wherein oxidizing a top surface of the PPI structure comprises an oxygen plasma treatment.
16. The method of claim 14 , wherein the oxygen plasma treatment comprises:
exposing the top surface of the PPI structure to an oxygen plasma, wherein the oxygen plasma is created by exciting oxygen gas over the PPI structure; and
applying a voltage under the substrate.
17. The method of claim 14 , wherein oxidizing a top surface of the PPI structure comprises treating the substrate with a wet chemical.
18. The method of claim 14 , wherein the oxidizing a top surface of the PPI structure creates a thin oxide film layer having a thickness greater than about ten nanometers.
19. The method of claim 18 , further comprising:
patterning an opening in the polymer layer and the thin oxide film layer, wherein the opening exposes a portion of the PPI structure;
forming an under bump metallurgy (UMB), wherein at least a portion of the UMB extends into the opening in the polymer layer and the thin oxide film layer and is electrically connected to the PPI structure; and
forming a bond ball on the UMB.
20. The method of claim 18 , wherein the PPI structure comprises copper, the thin oxide film layer comprises copper oxide, and the polymer layer is selected from a group consisting of polyimide (PI), polybenzoxazole (PBO), benzocyclobuten (BCB), epoxy, silicone, acrylates, nano-filled pheno resin, siloxane, fluorinated polymer, polynorbornene, and combinations thereof.