Composite bump structure and methods of fabrication

A method of forming composite bumps, comprising the steps of:

• providing an integrated circuit element or substrate with input/output pads on the top surface of said integrated circuit element or substrate;
• forming a dielectric layer over the top surface of said integrated circuit element or substrate having contact openings directly over said input/output pads, wherein said contact openings expose at least a part of each said input/output pad;
• forming a base metal layer over said dielectric layer covering said input/output pads;
• forming composite bumps on said base metal layer, wherein each said composite bump comprises a polymer body covered by a conductive metal coating;
• and
• removing part or all of that part of said base metal layer which is not covered by said composite bumps and does not cover said/input output pads.

A method of forming composite bumps, comprising the steps of:

• providing an integrated circuit element or substrate with input/output pads on the top surface of said integrated circuit element or substrate;
• forming a dielectric layer over the top surface of said integrated circuit element or substrate having contact openings directly over said input/output pads wherein said contact openings expose at least a part of each said input/output pad;
• forming a first photoresist layer on the top surface of said dielectric layer covering said input/output pads;
• forming a first photoresist mask in said first photoresist layer having openings over said input/output pads;
• forming a base metal layer on the top surface of said first photoresist mask, on the top surface of said dielectric layer not covered by said first photoresist mask, and on said input/output pads not covered by said dielectric layer;
• removing said first photoresist mask thereby removing that part of said base metal layer on the top surface of said first photoresist mask and forming base metal pads;
• forming composite bumps on said base metal pads wherein each said composite bump comprises a polymer body covered by a conductive metal coating.