Patent ID: 7713860

Claim:
A method of forming a metallic bump for establishing electrical contact to an I/O pad of a semiconductor device, comprising the steps of: preparing said semiconductor device having at least said I/O pad for electrical connection; forming an under bump metallurgy (UBM) on a top side of said I/O pad for electrical connection to said I/O pad; forming an isolative layer and a metallic foil sequentially in this order on a top side of said semiconductor device to cover said UBM entirely; forming a via by removing a part of said isolative layer and said metallic foil until a substantial part of said top side of said UBM is exposed; forming a thin metallic layer at least in said via; forming resist on a top side of said metallic foil without covering said via coated with said thin metallic layer; forming said metallic bump in said via on said top side of said UBM by using said metallic foil and said thin metallic layer jointly to conduct electrical current; and removing said resist and said metallic foil.