Nanoelectronics arrives with five nanotesla noise shielding

As electronics research shifts to ever smaller scales, stable laboratory environments  becomes increasingly important, says Matthias Kaiserswerth, director of the IBM Zurich Research Laboratory.  "If you're trying to design a new transistor by manipulating individual electrons moving through a carbon nanotube, any disturbance--a truck rumbling past or a nearby vacuum cleaner - can disrupt your experiment and leave you with irreproducible results.

"What we're trying to get to is something that is truly noise free, shielding against all these influences," says Kaiserswerth. "These kinds of facilities will become for nanoelectronics what clean rooms are for conventional silicon electronics."

Henry Smith, co-director of MIT's Nanostructures Laboratory, is not so sure. "There is no firm evidence that such facilities are needed," he says. "Active isolation of vibration is a better solution and at much lower cost."

But Xiang Zhang, director of the Nano-Scale Science and Engineering Center at the University of California, Berkeley, says that it's precisely IBM's willingness to push to perfection with its new facility that will create keen interest in the nanotech community.

The new labs are part of a $90m, 65,000sq.ft facility being collaboratively built by IBM with the Swiss Federal Institute of Technology, also in Zurich. One-third of the $90m will go toward building 10,000sq.ft  of clean-room facilities and 2,000sq.ft. of noise-free labs. Although nanotech labs elsewhere are shielded in various ways, says Kaiserswerth, "this 200m2 will be unique. These noise-free labs will give us a competitive edge so we can move forward faster."

"IBM is in the business of making computer chips," says Kaiserswerth. "But we have been struggling in the last few years to meet Moore's Law in terms of doubling the number of transistors on a chip and doubling the clock rate." Techniques that the industry has traditionally used to increase circuit density are beginning to bump up against silicon's fundamental physical limits. So many companies and research centers are trying to develop novel ways to store information and perform computations

For example, IBM is looking at building transistors from nanowires, using tiny magnetic forces exerted by electrons to store information, and slowing and bending light in ways that make it possible to carry out computations with photons instead of electrons.

"Once you move into atomic-scale research, you are dealing with very low energy levels, and so you need very sensitive instruments," says Kaiserswerth. The more sensitive the instrument, the more responsive to disturbances in the environment. "Every time we bought a new piece of equipment," says Paul Seidler, IBM Zurich's science and technology manager, "we would find ourselves having to think hard about which lab was most suitable."

"And as nanotechnology progresses in making ever smaller structures that demand higher precision, many labs will increasingly find this a problem," says Kaiserswerth. Zhang agrees. "It's something the industry will have to address," he says.

Each lab in IBM's new facility will have test benches mounted on separate concrete blocks, elastically supported by pneumatic dampers. These in turn will be mounted on vibration-absorbing high-mass concrete slabs. This double floor will eliminate even vibrations caused by people entering the room.

Similarly, the labs will effectively be encased in cages that act like passive electromagnetic shields to protect against permanent electromagnetic fields, such as those caused by nearby railways or other labs. Sensor-based active shielding will compensate for any periodic electromagnetic disturbances. "We can shield down to five nanotesla, or one-10,000th of the earth's magnetic field," says Kaiserswerth.

"This is the next level of precision," says Seidler. "In many respects, it's an indication that nanoelectronics has arrived."

 Model of Nanoscale Exploratory Technology Laboratory in Rüschlikon. Courtesy: IBM
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