"CHIPS: Water-filled wafers streamline chip cooling"

Georgia Institute of Technology researchers have developed a chip-cooling process that they hope will replace the bulky, bolt-on metal towers used with microprocessors like the G5. Instead of an entire tower through which water circulates, they have created water-filled wafers that can be integrated on self-cooling pc boards. The boards, which are being fabricated by the Microelectronics Advanced Research Corp. (Marco), will provide the plumbing for flip-chip-mounted ICs. In the streamlined cooling system envisioned by the researchers, water will circulate through the silicon substrates of microprocessors and other system-level chips by virtue of trenches etched on the otherwise unused backside of the wafer. "We have applied for the patents with Marco, and so far we have garnered interest in licensing our technology from over a dozen major semiconductor makers," said Georgia Institute of Technology EE Bing Dang. The researcher co-invented the technique in collaboration with professors Paul Kohl and James Meindl and their research assistants Paul Joseph, Muhannad Bakir and Todd Spencer. Although the technique is still in the prototype stage, the EEs have succeeded in fabricating very deep trenches that are only about 100 microns wide in the backside of wafers. Normally that side remains unused, but the new technique utilizes almost the entire surface area of that side for cooling. Because the water circulates through the silicon chips themselves, which have excellent thermal conductivity, the approach promises to cool chips much more efficiently than the customary metal cooling towers.
Text: http://www.eetimes.com/showArticle.jhtml?articleID=165600142