Patent ID: 9543262
Date: 2017-01-10
CPC Classifications: H01L

Claim:
1. A method comprising: blanket depositing a seed layer on a surface of a substrate; forming a first photoresist layer over the substrate and patterning a first opening in the first photoresist layer exposing a portion of the seed layer; electroplating a redistribution layer on the portion of the seed layer exposed in the first opening; removing the first photoresist layer using a sodium carbonate or potassium hydroxide based solution; forming a second photoresist layer over the substrate and patterning a second opening in the second photoresist layer exposing a portion of the redistribution layer; forming a self-aligned stud bump by sequentially electroplating a bulk metal layer on the portion of the redistribution layer exposed in the second opening and a cap layer on the bulk metal layer to form a completed stud bump in the opening without forming an additional photoresist layer; removing the second photoresist layer from the substrate to expose a portion of the seed layer using a sodium carbonate or potassium hydroxide based solution; removing the exposed portion of the seed layer; screen printing a passivation layer over the substrate, seed layer, redistribution layer and the completed stud bump; and etching back the passivation layer to expose a portion of the cap layer, so that a top surface of the stud bump is above a top surface of the passivation layer, and the seed layer, the redistribution layer, the bulk metal layer and at least a portion of sidewalls of the cap layer are encapsulated by the passivation layer.