March/April 2009

From the Labs: Information Technology

New publications, experiments and breakthroughs in information technology--and what they mean.

By Kate Greene

Brrr: A thermoelectric cooler, at the center, on a copper plate.
Credit: Macmillan Publishers, Ltd: Nature Nanotechnology vol. 4, issue 1 © 2009

Chip Chiller
On-chip cooling could increase performance and decrease power consumption

Source: "On-chip cooling by superlattice-based thin-film thermoelectrics"
Ravi Prasher et al.
Nature Nanotechnology online, January 25, 2009

Results: Researchers at Intel, Arizona State University, and Nextreme Thermal Solutions and RTI International, both located in North Carolina, have integrated a thermo­electric cooler into a computer chip for the first time. The semiconductor-based device, which uses electric current to move heat from one place to another, cooled a targeted region in a chip by 15 °C.

Why it matters: When microprocessors and opto­electronics operate, they generate heat; too much can inhibit performance and reduce reliability. Today's cooling systems use flat metal plates attached to a chip to disperse the heat, and metal heat sinks, fans, and liquid-based cooling systems to remove it. But these tech­nologies are bulky and inefficient. If small thermoelectric coolers could be built onto the heat-dissipating metal plates to target hot spots in the chip, they could replace other cooling systems and save space. Such focused cooling might also consume less energy.

Methods: The researchers selected thermoelectric coolers made from nanostructured thin films whose cooling properties had been proved superior to those of bulk thermoelectric materials. To attach a cooler to a copper plate already incorporated into the chip packaging, they applied an insulating material to the copper and deposited metal lines to serve as electrical connections to the cooler. Then they filled the spaces between the lines with a ­polymer for mechanical ­stability and soldered the cooler to the lines.

Next steps: Thermal resistance in the contact point between the cooler and the copper plate keeps the integrated device from cooling as effectively as a stand-alone device would. To reduce this resistance, the researchers are exploring alternative connectors, such as special types of solder and carbon nanotubes. They also plan to use more thermoelectric coolers to cover all the hot spots on a chip.