LOW FABRICATION COST, HIGH PERFORMANCE, HIGH RELIABILITY CHIP SCALE PACKAGE
First Claim
1. A method for fabricating a metal bump over a device, comprising:
- providing a silicon substrate, a copper pad over said silicon substrate, a passivation layer over said silicon substrate, and a polymer layer on said passivation layer, wherein an opening in said passivation layer and in said polymer layer exposes said copper pad;
forming a first metal layer over said copper pad and over said polymer layer;
forming a first photoresist layer on said first metal layer, an opening in said first photoresist layer exposes said first metal layer;
forming a second metal layer on said first metal layer exposed by said opening in said first photoresist layer;
removing said first photoresist layer;
forming a second photoresist layer on said second metal layer, wherein an opening in said second photoresist layer exposes said second metal layer;
electroplating a copper pillar over said second metal layer exposed by said opening in said second photoresist layer, wherein said copper pillar has a height between 10 and 100 micrometers;
electroplating a nickel layer over said copper pillar in said opening in said second photoresist layer, wherein said nickel layer has a thickness between 1 and 10 micrometers;
electroplating a solder layer directly on said nickel layer in said opening in said second photoresist layer, wherein said solder layer has a thickness between 10 and 100 micrometers;
removing said second photoresist layer; and
reducing a transverse dimension of said copper pillar to be smaller that said height of said copper pillar and removing said first metal layer not under said second metal layer.
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Accused Products
Abstract
The invention provides a new method and chip scale package is provided. The inventions starts with a substrate over which a contact point is provided, the contact point is exposed through an opening created in the layer of passivation and a layer of polymer or elastomer. A barrier/seed layer is deposited, a first photoresist mask is created exposing the barrier/seed layer where this layer overlies the contact pad and, contiguous therewith, over a surface area that is adjacent to the contact pad and emanating in one direction from the contact pad. The exposed surface of the barrier/seed layer is electroplated for the creation of interconnect traces. The first photoresist mask is removed from the surface of the barrier/seed layer. A second photoresist mask, defining the solder bump, is created exposing the surface area of the barrier/seed layer that is adjacent to the contact pad and emanating in one direction from the contact pad. The solder bump is created in accordance with the second photoresist mask, the second photoresist mask is removed from the surface of the barrier/seed layer, exposing the electroplating and the barrier/seed layer with the metal plating overlying the barrier/seed layer. The exposed barrier/seed layer is etched in accordance with the pattern formed by the electroplating, reflow of the solder bump is optionally performed.
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Citations
20 Claims
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1. A method for fabricating a metal bump over a device, comprising:
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providing a silicon substrate, a copper pad over said silicon substrate, a passivation layer over said silicon substrate, and a polymer layer on said passivation layer, wherein an opening in said passivation layer and in said polymer layer exposes said copper pad; forming a first metal layer over said copper pad and over said polymer layer; forming a first photoresist layer on said first metal layer, an opening in said first photoresist layer exposes said first metal layer; forming a second metal layer on said first metal layer exposed by said opening in said first photoresist layer; removing said first photoresist layer; forming a second photoresist layer on said second metal layer, wherein an opening in said second photoresist layer exposes said second metal layer; electroplating a copper pillar over said second metal layer exposed by said opening in said second photoresist layer, wherein said copper pillar has a height between 10 and 100 micrometers; electroplating a nickel layer over said copper pillar in said opening in said second photoresist layer, wherein said nickel layer has a thickness between 1 and 10 micrometers; electroplating a solder layer directly on said nickel layer in said opening in said second photoresist layer, wherein said solder layer has a thickness between 10 and 100 micrometers; removing said second photoresist layer; and reducing a transverse dimension of said copper pillar to be smaller that said height of said copper pillar and removing said first metal layer not under said second metal layer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for fabricating a metal bump over a device, comprising:
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providing a silicon substrate, a copper pad over said silicon substrate, and a passivation layer over said silicon substrate, wherein an opening in said passivation layer exposes said copper pad; forming a first metal layer over said copper pad and over said passivation layer; forming a first photoresist layer on said first metal layer, an opening in said first photoresist layer exposes said first metal layer; forming a second metal layer on said first metal layer exposed by said opening in said first photoresist layer; removing said first photoresist layer; forming a second photoresist layer on said second metal layer, wherein an opening in said second photoresist layer exposes said second metal layer; electroplating a copper pillar over said second metal layer exposed by said opening in said second photoresist layer, wherein said copper pillar has a height between 10 and 100 micrometers; electroplating a nickel layer over said copper pillar in said opening in said second photoresist layer, wherein said nickel layer has a thickness between 1 and 10 micrometers; electroplating a solder layer directly on said nickel layer in said opening in said second photoresist layer, wherein said solder layer has a thickness between 10 and 100 micrometers; removing said second photoresist layer; and reducing a transverse dimension of said copper pillar to be smaller that said height of said copper pillar and removing said first metal layer not under said second metal layer. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method for fabricating a metal bump over a device, comprising:
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providing a silicon substrate, a copper pad over said silicon substrate, a passivation layer over said silicon substrate, and a polymer layer on said passivation layer, wherein an opening in said passivation layer and in said polymer layer exposes said copper pad; forming a first metal layer over said copper pad and over said polymer layer; forming a first photoresist layer on said first metal layer, an opening in said first photoresist layer exposes said first metal layer; forming a second metal layer on said first metal layer exposed by said opening in said first photoresist layer; removing said first photoresist layer; forming a second photoresist layer on said second metal layer, wherein an opening in said second photoresist layer exposes said second metal layer; electroplating a copper pillar over said second metal layer exposed by said opening in said second photoresist layer, wherein said copper pillar has a height between 10 and 100 micrometers; electroplating a solder layer over said copper pillar in said opening in said second photoresist layer, wherein said solder layer has a thickness between 10 and 100 micrometers; removing said second photoresist layer; reducing a transverse dimension of said copper pillar to be smaller than said height of said copper pillar and removing said first metal layer not under said second metal layer.
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- 16. The method of claim 16, wherein said first metal layer comprises titanium.
Specification