Flip chip packaging rework
AssigneeInternational Business Machines Corporation
InventorsCharles Leon Arvin, Karen P. McLaughlin, Thomas Anthony Wassick, Brian W. Quinlan
Life of this patent
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Abstract
Rework and recovery processes generally include application of liquid metal etchant compositions to selectively remove one layer at a time of a solder layer and underball metallurgy multilayer stack including a titanium-based adhesion layer, a copper seed layer, a plated copper conductor layer, and a nickel-based barrier layer. The rework and recovery process can be applied to the dies, wafers, and/or substrate.
Claims20
A process for reworking and recovering a die for a flip chip application, the process comprising:
- providing the die comprising a plurality of under-bump metallurgy (UBM) stacks on a substrate, wherein each of the UBM stacks is in contact with a first bond pad and is formed in a trench to the first bond pad defined by a passivation layer and a polyimide layer, wherein each of the UBM stacks comprises a sputtered adhesion layer including a seed layer thereon, a plated conductive layer, and a barrier layer;
- and solder in direct contact with the UBM stacks, wherein an intermetallic forms at an interface between each of the UBM stacks and the solder;
- applying a liquid etchant to selectively remove one layer at a time each of the solder, the barrier layer, the plated conductive layer, and the sputtered adhesion layer;
- removing the polyimide layer;
- depositing a nitride layer;
- depositing and patterning a photosensitive polyimide layer to expose the first bond pad;
- depositing and patterning a redistribution layer extending from the first bond pad to a second bond pad at a different location;
- depositing and patterning a passivation layer to expose the second bond pad;
- and
- forming a second UBM stack and a second solder ball thereon on the second bond.
A process for reworking and recovering a substrate for a flip chip application, the process comprising:
- applying a liquid etchant to selectively remove solder from the substrate;
- removing a solder mask and a copper short;
- applying and patterning a solder mask;
- curing the substrate;
- exposing the solder mask to an oxygen plasma ash process to roughen a surface thereof;
- and
- reapplying solder to the substrate.
A process for reworking and recovering a wafer for a flip chip application, the process comprising:
- providing the wafer comprising a plurality of under-bump metallurgy (UBM) stacks, wherein each of the UBM stacks is in contact with a bond pad and is formed in a trench opening in a passivation layer and a polyimide layer to the bond pad, wherein each of the UBM stacks comprises a titanium-based adhesion layer, a copper-based conductive layer, a sputtered copper seed layer, and a nickel-based barrier layer;
- and a solder in direct contact with the UBM stacks, wherein an intermetallic forms at an interface between the UBM stacks and the solder;
- applying a liquid etchant to selectively remove one layer at a time each of the solder, the nickel-based barrier layer, the copper-based conductive layer, the titanium based adhesion layer and the intermetallic;
- oxygen plasma ashing the polyimide surface to increase surface roughness thereon;
- sputter depositing a titanium adhesion layer and a copper based seed layer onto the bond pad and the polyimide;
- applying, exposing, and developing a photoresist onto the titanium-based adhesion layer to form a pattern;
- plating a copper-based conductor layer and a nickel-based barrier layers onto the exposed portion of the sputtered copper-based seed layer and titanium adhesion layers in the pattern;
- and
- etching the copper-based conductor layer and the nickel-based barrier layer to reform the UBM stack.
Dependencies are inferred from the claim text.