Microsoft Technology Licensing, LLC

Christopher A Cantaloube

David Bazeley Tuckerman

Richard P Rouse

Flavio Griggio

Cliff C Lee

A cryogenic under bump metallization (UBM) stack includes an adhesion and barrier layer and a conductive pillar on the adhesion and barrier layer. The conductive pillar functions as a solder wetting layer of the UBM stack and has a thickness. An indium superconducting solder bump is on the conductive pillar. The thickness of the conductive pillar is sufficient to prevent intermetallic regions, which form in the conductive pillar at room temperature due to interdiffusion, from extending through the entire thickness of the conductive pillar to maintain the structural integrity of the UBM stack. The indium (In) solder bump may be formed through electroplating, with the conductive pillar being copper (Cu) and the adhesion and barrier layer being titanium tungsten (TiW) and a thin seed layer of copper (Cu), or a layer of titanium (Ti).

Electroplated indium bump stacks for cryogenic electronics

An integrated circuit is provided that comprises a first substrate having a plurality of conductive contact pads spaced apart from one another on a surface of the first substrate, a dielectric layer overlying the first substrate and the plurality of conductive contact pads, and a second substrate overlying the dielectric layer. A plurality of superconducting contacts extend through the second substrate and the dielectric layer to the first substrate, wherein each superconducting contact of the plurality of superconducting contacts is aligned with and in contact with a respective conductive contact pad of the plurality of conductive contact pads.

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Christopher A Cantaloube