The IBM Research – Zurich lab presented their latest development to Angela Merkel at this year’s CeBIT – a 3D chip assembly cooled only by 50 micrometer thin coolant channels. The technique was developed in collaboration with the Fraunhofer Institute for Reliability and Microintegration IZM as part of a jointly supervised PhD dissertation and may lead to supercomputers the size of sugar cubes.

IBM Head Sam Palmisano presented Chancellor Merkel with the first prototype of the stacked chip at the technology trade fair’s opening ceremony. Much research and development has gone into the 3D assembly of computer chips over recent years in order to improve processor performance even more. Apart from reducing the chip surface area, the data connections between the chip levels have been shortened to increase speed. A stumbling block was that, although the chips are smaller than their non-stacked competitors, they also run a lot hotter. Conventional cooling solutions were unable to overcome the problem. IBM finally found a solution in a close cooperation with Fraunhofer IZM Berlin and TU Berlin, who specialize in thermal management and the reliability of chip architecture*.

The technology introduced by IBM at CeBIT is based on a water-cooling system. Instead of cooling the outside of the complete stack, hair-thin channels were integrated in the assembly. A particular challenge was the assembly of the electronics, as the tiny cooling channels have to skirt the many thousands of electronic data connections. Directly integrating water-cooling into the 3D chip also means that the thermal management is scalable. In principle, countless stacked chips can be cooled by adaptively matching them to power distribution of the individual chips. The prototype has a capacity of 180 watt/cm², enough power to meet the cooling requirements of such complex assemblies.

Chancellor Merkel, who was visibly impressed by the technology, was able to leave CeBIT with a small piece of tomorrow’s IT, technology that will likely make its way into all our lives in the future.

*The design and assembly of the 3D cooling concept is based on the dissertation “Interlayer cooling of 3D chip stacks” by Dr. Thomas Brunschwiler at IBM Research – Zurich, which was supervised by Fraunhofer IZM’s Prof. Herbert Reichl, Prof. Bernhard Wunderle and Dr. Hermann Oppermann.