Cleanrooms for research at the nanoscale

The chips that power today’s information technology revolution begin their existence with a tiny “seed” crystal dipped into a crucible of molten silicon. Around the seed, untold numbers of silicon atoms align themselves perfectly with the seed’s crystalline structure, creating a self-assembled single-crystal ingot of silicon the diameter of a dinner plate and up to five feet long. From that ingot, wafers are cut to provide the foundations for integrated circuits used in computers, cell phones, medical equipment and a host of other modern electronic marvels.

Formation of the ingot provides an example of “bottom-up” nanotechnology, in which the tiniest of silicon units – atoms – come together to create a larger object using a self-assembly process that proceeds on its own, governed by the laws of physics.

To make integrated circuits, however, the wafers must be topped by intricate patterns of transistors, insulating layers, interconnects and other structures grown using “top-down” processes. These processes create small structures from large ones through techniques that include photolithography.

This complex fusion of “top-down” and “bottom-up” technology has produced increasingly powerful and less expensive electronic devices at a steady pace for the past 50 years. But scientists can now see the end of the road for these advances because semiconductor feature sizes simply can’t be made much smaller with current technology.

What will replace silicon integrated circuits at the heart of technology innovation?

Jim Meindl doesn’t know exactly, but he believes it will involve the fusion of another set of top-down and bottom-up technologies – this one involving the basic mechanisms that govern living creatures. As director of Georgia Tech’s Nanotechnology Research Center, Meindl has led the development of a US$80m (€55m) facility that will support the institute’s vision for a new kind of technology based on the merger of biological and physical sciences at the nanometer scale.

“Plants, animals and people are the most stunning examples of self-assembly that anyone can point to,” he notes. “I believe it is going to take another, more elegant, clever and spectacular fusion of bottom-up and top-down nanotechnology to get the breakthrough we need to move from silicon to whatever is next. That’s what we are going to try to do in this new facility.”

To accommodate that vision, the new Marcus Nanotechnology Building on the northern part of the Georgia Tech campus will provide 20,000 square feet (ft2) of cleanroom space devoted to traditional nanotechnology based on the physical sciences – next to 10,000 ft2 of cleanroom space devoted to biologically based nanotechnology.

Construction has already begun, but realising this vision in concrete and steel won’t be easy. Traditional microelectronics cleanrooms operate under positive pressure to keep dust out, and limit humidity. Life sciences cleanrooms work under negative pressure to keep microbes in.

Biotech and physics fusion

“I’m not aware of another facility in the world that has been designed to do this integration from the beginning,” Meindl adds. “I believe we can do things with this fusion of biological nanotechnology and physical nanotechnology that will be very exciting.”

With its collaborators at Emory University and other leading institutions, Georgia Tech’s nanotechnology and nanoscience programme has already demonstrated the potential for merging the disciplines. Three major research initiatives totalling more than $40m (€27m) are funding nanotech research to develop new ways of fighting cancer and repairing DNA damage, for example.

“In nano-medicine, we have combined a top engineering school with top medical schools, and we are now in a unique position to be able to move into nanomedicine very effectively,” says Charles Liotta, Georgia Tech’s vice provost for research and graduate studies. “Nanotechnology and nanoscience are platform technologies that impact many other areas of science and technology. We aim to take advantage of what happens at the boundaries between these disciplines.”

Liotta sees more collaboration ahead and benefits for industrial companies, including those based in Georgia.

“No one university can do everything on its own,” he stresses. “Nobody has all the intellectual capital or the facilities to meet the needs of interdisciplinary research today.”

Liotta points to Oak Ridge National Laboratory, Imperial College in the UK and the National Nanotechnology Infrastructure Network (NNIN) as examples of Georgia Tech’s collaborative approach in nanotechnology.

He expects the new 160,000 ft2 facility to serve as a magnet for industrial companies wanting to share in Georgia Tech’s vision for technology at the smallest of scales.

“We feel that this new Nanotechnology Research Building will attract industry to partner with our researchers,” Liotta explains. “We look at the new building as not the just vehicle for doing nanoscience and nanotechnology, but also as an outreach to industry so we can transfer technology developed here and jointly develop new technology.”

That collaboration has already begun. In the Joseph M. Pettit Microelectronics Research Center – currently a campus focal point for nanotechnology and nanoscience – more than two dozen industrial companies use the cleanroom facilities, Meindl says.

Georgia Tech has made significant investments in new equipment for nanotechnology, including an electron-beam lithography tool able to produce feature sizes as small as five to 10 nanometers. The device was purchased with support from the Georgia Research Alliance.

Beyond industrial collaborators, the facilities are used by all five of the other Georgia Research Alliance universities, making it truly a Georgia resource. Meindl wants the same thing to happen with the new building, which will be the most advanced facility of its kind in the southeast when it opens in mid-2008.

“This new building is going to give us a new opportunity to provide nanotechnology research services to the state in a significant way,” he says. “We really are motivated and we can do it. We have a vision and we are putting resources behind that vision.”

Such collaboration is encouraged by the National Nanotechnology Infrastructure Network – a National Science Foundation-supported organisation that brings together 13 leading US universities to share facilities and facilitate collaborations with industry.

Georgia Tech is a national leader in the ancillary technologies associated with integrated circuits, addressing such key issues as interconnects, cooling, power supply and packaging.

Today, it is part of the Focus Center Research Program, supported by the Defense Advanced Research Projects Agency (DARPA) and the semiconductor industry. Other universities involved include Stanford, MIT, the University of California at Berkeley and the University of Texas.

Through its Microsystems Packaging Research Center – supported by the National Science Foundation and industry partners – Georgia Tech has led efforts to further shrink electronic equipment through “system-on-package” technology that goes beyond Moore’s Law.

At the groundbreaking ceremony for the new building in August, Georgia Tech President Wayne Clough vowed that the institute would be a national leader in nanotechnology, with the new facility fuelling rapid growth in Georgia Tech’s nanotechnology research.