Chip packages
Chip assemblies are disclosed that include a semiconductor substrate, multiple devices in and on the semiconductor substrate, a first metallization structure over the semiconductor substrate, and a passivation layer over the first metallization structure. First and second openings in the passivation layer expose first and second contact pads of the first metallization structure. A first metal post is positioned over the passivation layer and over the first contact pad. A second metal post is positioned over the passivation layer and over the second contact pad. A polymer layer is positioned over the passivation layer and encloses the first and second metal posts. A second metallization structure is positioned on the polymer layer, on the top surface of the first metal post and on the top surface of second metal post. The second metallization structure includes an electroplated metal. Related fabrication methods are also described.
1. An integrated circuit chip comprising:
a silicon substrate;
multiple devices in and on said silicon substrate, wherein said multiple devices comprise a transistor;
a first dielectric layer over said silicon substrate;
a first metallization structure over said first dielectric layer, wherein said first metallization structure comprises a first metal layer and a second metal layer over said first metal layer;
a second dielectric layer between said first and second metal layers;
a passivation layer over said first metallization structure and over said first and second dielectric layers, wherein a first opening in said passivation layer is over a first contact point of said first metallization structure, and said first contact point is at a bottom of said first opening, and wherein a second opening in said passivation layer is over a second contact point of said first metallization structure, and said second contact point is at a bottom of said second opening;
a first metal post on said first contact point, wherein said first metal post comprises a third metal layer on said first contact point and a copper layer having a thickness between 3 and 100 micrometers on said third metal layer;
a second metal post on said second contact point, wherein a pitch between said first and second metal posts is between 25 and 100 micrometers; and
a second metallization structure on a top surface of said first metal post and on a top surface of second metal post, wherein said second metallization structure comprises a tin-containing layer over said first and second metal posts.
2. The integrated circuit chip of claim 1 further comprising a polymer layer on said passivation layer, wherein said polymer layer contacts a sidewall of said copper layer.
3. The integrated circuit chip of claim 2 , wherein said polymer layer has a thickness between 20 and 100 micrometers.
4. The integrated circuit chip of claim 1 , wherein said tin-containing layer comprises silver.
5. The integrated circuit chip of claim 1 , wherein said tin-containing layer is on a nickel layer of said second metallization structure.
6. The integrated circuit chip of claim 1 , wherein said first metal layer comprises electroplated copper.
7. The integrated circuit chip of claim 1 , wherein said first metal layer comprises electroplated copper and said second metal layer comprises an aluminum layer over said first metal layer.
8. The integrated circuit chip of claim 1 , wherein said passivation layer comprises a nitride layer.
9. The integrated circuit chip of claim 1 , wherein said passivation layer comprises a silicon-oxynitride layer.
10. The integrated circuit chip of claim 1 , wherein said third metal layer comprises titanium.
11. The integrated circuit chip of claim 1 , wherein said first and second metal posts are further on said passivation layer.
12. The integrated circuit chip of claim 1 further comprising a polymer layer on said passivation layer, wherein a third opening in said polymer layer is over said first contact point, and a fourth opening in said polymer layer is over said second contact point, wherein said first metal post is connected to said first contact point through said third opening, and said second metal post is connected to said second contact point through said fourth opening.