Scientists at Bell Labs, the research and development arm of Lucent Technologies, have found a way to peer deep inside a semiconductor and create an image of a single impurity atom in silicon, a development that will help scientists understand how impurities affect the properties of microchips.
This understanding of semiconductors at the atomic level is critical in devising manufacturing technologies needed to shrink the size of future generations of high-speed electronics, such as microprocessors, in a bid to keep Moore's Law on track.
Moore's Law, observed by Intel co-founder Gordon Moore in 1965, posits that the number of transistors on a semiconductor doubles roughly every 18 months with a 50 percent reduction in area.
This is the first time that an individual impurity has been pictured in its undisturbed state within a crystal and was achieved using a special electron microscope, Bell Labs said, adding that such a feat is as difficult as seeing a footprint on the surface of the moon.
The research is described in an article published Thursday in the journal Nature.
The results "are important in understanding the distribution of impurities in silicon at an atomic level," wrote Paul Peercy, a professor and dean of engineering at the University of Wisconsin at Madison. "They will also be important in increasing our understanding of a wide range of complex materials."
As chips get ever smaller, it's now important both to image and understand the chemical and physical environment within devices, because those properties will ultimately determine to what lengths engineers will be able to shrink the sizes of transistors and interconnections among them in semiconductors, said Elsa Reichmanis, director of the materials research department at Bell Labs.
Impurities--or "dopants" as they are known--are purposefully introduced into silicon to provide charge carriers that control a chip's electrical properties. But as chip components continue to shrink in accordance with Moore's Law, the industry is reaching a point where just a few atoms of impurities could determine the function of a particular device, Bell Labs said.
The Bell Labs technique, which uses scanning transmission electron microscopy, enables scientists to view the individual dopants and clusters as they exist within actual devices, and will provide scientists with an understanding of how these impurity atoms function within real devices, Bell Labs said.
Previous techniques had not been able to look inside crystal.
"Now we can look at things hidden inside a solid, in their natural environment," said David Muller, a Bell Labs physicist. "It's as qualitatively different as seeing how an animal behaves in a zoo and how it behaves in its natural habitat."
The Bell Labs technique is extremely sensitive and can be applied to almost any material, not just semiconductors, Bell Labs said.
Other members of the research team were Paul Voyles, John Grazul and Paul Citrin of Bell Labs, and Hans Gossmann of Agere Systems.
April 26, 2002, 6:00 AM PT
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