DARPA targets three-dimensional chip-cooling tech

Posted by Thomas Anderson

Researchers from the Georgia Institute of Technology have clinched a Defense Advanced Research Projects Agency (DARPA) contract to develop three-dimensional chip-cooling technology capable of handling heat loads as much as ten times greater than systems commonly used today.

In addition to higher overall chip heat dissipation demands, the new approach will also handle on-chip hot-spots that dissipate considerably more power per unit area than the remainder of the device.

Such cooling demands may be needed for future generations of high-performance integrated circuits embedded in a wide range of military equipment.

"There is really no good way to address this heat dissipation need with existing technology, and the problem is getting worse because computing power is increasing and the capabilities being put on chips are expanding," explained Yogendra Joshi, a professor in Georgia Tech’s Woodruff School of Mechanical Engineering and the project’s principal investigator.

"There is a real need for developing schemes that can address high power on the whole chip coupled with very high power dissipation areas that are only a few millimeters square."

DARPA’s Microsystems Technology Office, which provided the three-year $2.9 million contract, is seeking techniques to dissipate heat of as much as one kilowatt per square centimeter in the overall integrated circuit, and five kilowatts per square centimeter on smaller areas. The research is part of DARPA’s Intrachip/Interchip Enhanced Cooling (ICECool) program.

"The approaches that we are talking about are relatively high-risk," said Joshi, who specializes in electronic cooling from the chip-level on up to full-sized data centers.

"They have not been tried before, so there are real questions of reliability – whether they can hold up under repeated cycles of being powered up and powered down."

As Joshi explains, while applications for the high-powered chips aren’t specified, their installation in systems intended for field use will add to the level of challenge.

"For speed and performance issues, this computing power may be embedded where it is needed in the field," he noted. "The challenges of cooling these high performance integrated circuits will be even more challenging because they will operate in environments that may be adverse compared to an office or computer room situation."

Muhannad Bakir, an associate professor in the Georgia Tech School of Electrical and Computer Engineering, expressed similar sentiments.

"It is well known that cooling constraints play a critical role in designing electronic systems. Often a favorable electronic system configuration may not be realizable due to lack of adequate cooling," Bakir explained.

"The novel microscale thermal technologies that will result from this project will address the most demanding thermal needs of future heterogeneous 3-D nanoelectronic systems and will enable new levels of performance and energy efficiency"

Beyond the technology challenges, says Joshi, the researchers will also need to develop a detailed and fundamental understanding of how liquids boil at the micron size scale.

"The physics of how liquids boil has been well studied for large systems such as power plant boilers... What we are talking about here is boiling that will take place in passages that are produced by microfabrication techniques that may be only 50 micrometers by 50 micrometers. The physics of what will be going on there is very different than what happens at the large scale, and how these liquids boil in the passages of interest will result in new scientific insights."

The above-mentioned research will be conducted in collaboration with industry partner Rockwell-Collins, a major manufacturer of electronic systems for the military. That collaboration will help ensure that solutions developed will be compatible with defense system requirements.

"The technologies we have proposed aim to explore uncharted territory in multiple science and technology domains to bring about an order-of-magnitude improvement in the current state-of-the-art," added Andrei Fedorov, a professor in the Georgia Tech School of Mechanical Engineering.

"The project represents a significant challenge on the most fundamental level of materials and fluid behavior down to the sub-micron scale. We’re confident that this project will produce some really new technologies to address the needs of future 3D microsystems."