Bell Labs Invention Could Mean Cooler Chips

Bell Labs, the research arm of Lucent Technologies Inc., has developed a method of using micro-amounts of liquid that could help solve a major problem with today's powerful microprocessors -- heat.

While chips powering laptops and computers have gotten faster and faster, they have also gotten hotter and hotter, presenting engineers with a quandary. Chip-generated heat, for example, can cause blade servers in densely packed racks to overheat, and can suck up notebook battery juice by requiring power-hungry coolant systems.

A possible solution to the problem is Bell Labs's "nanograss," tiny tubes that can spray liquid on chip hot spots.

Cooling technology used today is applied to the entire chip surface, even though only portions of it require heat dissipation. Because cooling systems can't be localized, they are inefficient and use too much power, Tom Krupenkin, the Bell Labs scientist who led the research on nanograss, said.

To solve the problem, a chipmaker would plant nanograss on the walls of micro-channels etched on the chip's surface. That way, liquid would be applied only on the hot spots, with the excess flowing through the channel to a radiator sitting on top of the chip, so it can be cooled and reused."It's very much what you have in a car, with the liquid cooling of an engine," Krupenkin said. "You have a radiator that's the equivalent of a heat sink (on the top of the chip), and the engine would be the equivalent of the chip."

Because the coolant would be applied only where needed, heat would be more effectively dissipated. In addition, less power would be used, because less liquid would be circulated.

"You want to minimize the amount of liquid you push through because that requires less power," Krupenkin said.

The size of the nanograss will depend on its application. In the case of chips, they would be used in channels that could be as much as several hundred microns in diameter. A human hair is about a hundred microns.

Nano-grass has other applications besides in chip manufacturing. The technology could be used in biotechnology research to mix tiny amounts of liquids in genetic analysis, or in optical switches used in fiber-optic communications networks, Krupenkin said.Lucent is looking for partners interested in using the technology, and expects it to find its way into products over the next several years.