IBM makes breakthrough in cooling chips with water

5 Jun 2008

IBM researchers have made a breakthrough in cooling stack chips with water, a methodology that promises to advance Moore’s Law and reduce energy consumed by data centres.

For the first time IBM researchers, in collaboration with the Fraunhofer Institute in Berlin, demonstrated a prototype that integrates the water cooling system into the 3D chips by piping water directly between each layer in the stack.

These so-called 3D chip stacks – which take chips and memory devices that traditionally sit side-by-side on a silicon wafer and stacks them together on top of one another – present one of the most promising approaches to enhancing chip performance beyond its predicted limits.

The research team piped water into cooling structures as thin as a human hair (50 microns) between the individual chip layers in order to remove heat efficiently at the source.

“As we package chips on top of each other to significantly speed a processor’s capability to process data, we have found that conventional coolers attached to the back of a chip don’t scale. In order to exploit the potential of high-performance, 3D chip stacking, we need interlayer cooling,” explained Thomas Brunschwiler, project leader at IBM’s Zurich Research Laboratory. “Until now, nobody has demonstrated viable solutions to this problem.”

“This truly constitutes a breakthrough. With classic backside cooling, the stacking of two or more high-power density logic layers would be impossible,” said Bruno Michel, manager of the chip cooling research efforts at the IBM Zurich Lab.

The team overcame key technical challenges in designing a system that maximises the water flow through the layers, yet hermetically seals the interconnects to prevent water from causing electrical shorts. The complexity of such a system resembles that of a human brain, wherein millions of nerves and neurons for signal transmissions are intermixed but do not interfere with tens of thousands of blood vessels for cooling and energy supply, all within the same volume.

By Niall Byrne