IBM Cools 3-D Computer Chips With Water

IBM scientists unveiled a powerful and efficient technique to cool 3-D chip stacks with water. In collaboration with the Fraunhofer Institute in Berlin, they demonstrated a prototype that integrates the cooling system into a 3-D chip by piping water directly between each layer in the stack.


These so-called 3-D chip stacks—in which chips and memory devices that traditionally sit side-by-side on a silicon wafer are layered on top of one another—presents one of the most promising approaches to enhancing chip performance beyond its predicted limits.

This follows IBM's leadership in advancing chip-stacking technology in a manufacturing environment announced one year ago, which drastically shortens the distance that information needs to travel on a chip to just 1/1000th of that on 2-D chips and allows the addition of up to 100 times more channels, or pathways, for that information to flow.


IBM researchers are exploring concepts for stacking memory on top of processors and, ultimately, for stacking many layers of processor cores. But in such advanced scenarios, cooling becomes a formidable challenge.

Such 3-D chip stacks would have an unprecedented aggregated heat dissipation of close to 1 kilowatt in a volume of just half a cubic centimeter—10 times higher than any other human-made device. Most notably, power densities in these stacked processors are higher than in nuclear and plasma reactors.

Brunschwiler and his 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. Using the superior thermophysical qualities of water, scientists were able to demonstrate a cooling performance of up to 180 W/cm2 per layer for a stack with a typical footprint of 4 cm2.