International Business Machines Corporation

Erik J Roggeman

Randolph F Knarr

Emanuel Israel Cooper

Roger Allan Quon

Panayotis Constantinou Andricacos

Kamalesh K Srivastava

Tien-Jen Cheng

Jonathan H Griffith

Lisa A Fanti

David E Eichstadt

A method of creating a multi-layered barrier for use in an interconnect, a barrier for an interconnect, and an interconnect including the barrier are disclosed. The method includes creating the multi-layered barrier in a recess of the device terminal by use of a single electroplating chemistry to enhance protection against voiding and de-lamination due to the diffusion of copper, whether by self-diffusion or electro-migration. The barrier includes at least a first layer of nickel-rich material and a second layer of copper-rich material. The barrier enables use of higher current densities for advanced complementary metal-oxide semiconductors (CMOS) designs, and extends the reliability of current CMOS designs regardless of solder selection. Moreover, this technology is easily adapted to current methods of fabricating electroplated interconnects such as C4s.

Barrier for interconnect and method

Start with a semiconductor substrate with contacts exposed through an insulating layer. Form a base over the contacts, with the base composed of at least one metal layer. Then form a conductive metal layer over the base. Form a mask over the top surface of the conductive metal layer with C solder bump openings therethrough with the shape of C solder bump images down to the surface of the conductive metal layer above the contacts. Etch away the exposed portions of the conductive metal layer below the C solder bump openings to form through holes in the conductive metal layer exposing C solder bump plating sites on the top surface of the base below the C solder bump openings with the conductive metal layer remaining intact on the periphery of the through holes at the C solder bump plating sites. As an option, form a barrier layer over the plating sites next. Form C solder bumps on the plating sites on the base/barrier layer within the C solder bump openings, with the C solder bumps being in contact with the conductive metal layer on the periphery of the through holes. Remove the mask. Etch away the remainder of the conductive metal layer, and etch away the base aside from the C solder bumps forming BLM pads. Then reflow the C solder bumps to form C solder balls.

Sacrificial seed layer process for forming C4 solder bumps

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Fishkill, NY, United States of America

Erik J Roggeman