IBM Wissenschaftler bauen den weltweit kleinsten funktionsfähigen Computerschaltkreis

(PresseBox) () San Jose, Kalifornien, 24. Oktober 2002. IBM Forscher haben die kleinsten Computerschaltkreise der Welt gebaut und in Funktion getestet. Hierbei wurde ein innovativer neuer Ansatz aus der Nanotechnologie gewählt: Individuelle einzelne Moleküle bewegen sich über eine glatte, atomare Kupfer-Oberfläche wie Dominosteine in einer Kettenreaktion.

Die neue "Molekülkaskade" ermöglichte es den Forschern, lauffähige digitale, logische Elemente zu bauen, die 260.000 mal kleiner sind als diese, die heute in den modernsten Halbleiterchips eingesetzt werden.

Die Schaltkreise wurden erzeugt, indem ein genaues Muster von Kohlenmonoxid-Molekülen auf einer Kupferoberfläche aufgebracht wurden. Das Bewegen eines einzelnen Moleküls erzeugt eine Kaskade, wie ein einzelner Dominostein eine ganze Kettenreaktion in Gang bringen kann. Die Wissenschaftler erzeugten winzige Strukturen, die fundamentale digitale Funktionen darstellen (logische "Und" und "Oder"-Funktionen). Das Speichern und Wiederauffinden von Daten war im Experiment bereits möglich, sowie die nötige "Verkabelung", um diese Funktionen in funktionierenden Computerschaltkreisen zu erzeugen.

Der komplexeste Schaltkreis, den die Forscher erzeugt haben, ist ein 12 x 17 Nanometer (Milliardstel Meter) großes Bauteil. (Ein "Sortierer" mit drei Schnittstellen). Er ist so klein, daß 190 MILLIARDEN davon auf einen Radiergummi am Ende eines Bleistifts passen (Kreis mit 7mm Durchmesser). Ein Nanometer (10 Hoch -9 Meter) entspricht der Länge von 5-10 Atomen in einer Reihe!!!

Denkbare Anwendungsgebiete sind Sensoren, Messfühler, vor allem etwa im Gesundheitsbereich, und mikroskopisch kleine Geräte, bei denen eine einmal vorzunehmende Schaltung nötig ist (wie bei den umgekippten Dominosteinen ist es nicht möglich, "rückwärts"zu schalten, dafür nimmt man dann einfach weitere Schalter).

Fotos finden Sie im Internet-Link anbei: www.research.ibm.com/...

Weitere Informationen in der Original-Pressemeldung anbei!

Contact:
Michael Ross,
IBM Research, Almaden Research Center
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E-mail: mikeross@almaden.ibm.com

IBM scientists build world's smallest operating computing circuits

Domino-like motion of individual molecules performs computation

SAN JOSE, Calif. (Oct 24, 2002) -- IBM researchers have built and operated the world's smallest working computer circuits using an innovative new approach in which individual molecules move across an atomic surface like toppling dominoes.

The new "molecule cascade" technique enabled the IBM scientists to make working digital-logic elements some 260,000 times smaller than those used in today's most advanced semiconductor chips.

The circuits were made by creating a precise pattern of carbon monoxide molecules on a copper surface. Moving a single molecule initiates a cascade of molecule motions, just as toppling a single domino can cause a large pattern to fall in sequence. The scientists then designed and created tiny structures that demonstrated the fundamental digital-logic OR and AND functions, data storage and retrieval, and the "wiring" necessary to connect them into functioning computing circuitry.

The most complex circuit they built -- a 12 x 17-nanometer three-input sorter -- is so small that 190 billion could fit atop a standard pencil-top eraser 7mm (about 1/4-inch) in diameter. A nanometer is a billionth of a meter; the length of five to 10 atoms in a line.

"This is a milestone in the quest for nanometer-scale computer circuitry," said Andreas Heinrich, a physicist at IBM's Almaden Research Center in San Jose, Calif., and one of the lead authors of the research article published in today's online edition of Science Magazine, Science Express. "The molecule cascade is not only a novel way to do computation, but it is also the first time all of the components necessary for nanoscale computation have been constructed, connected and then made to compute. It is way smaller than any operating circuits made to date."

"Molecule cascades show how we are learning to harness the properties of very small structures," added IBM Fellow Don Eigler. "I was amazed at how rapidly we progressed from initial discovery to design and operation of functional circuitry."

"These structures are so small," added IBM Fellow Don Eigler, "that even if traditional semiconductor technology continued to improve at today's Moore's Law pace -- doubling feature density every 2.5 years -- it would take 45 years to get down to these circuit dimensions."

This new technique for computation is another indicator of how atomic and molecular behavior on the nanoscale differs from the more familiar realm of everyday materials. This molecule cascade and the quantum mirage that Eigler and colleagues discovered two years ago are intriguing examples of novel nanoscale science and information-processing approaches that also yield new insights in the properties and interactions of atoms, molecules and surfaces.

Heinrich, Eigler and colleagues Christopher Lutz and Jay Gupta are continuing their exploratory research to find additional nanometer-scale computing systems based on the cascade mechanism.

Technical details

IBM's molecule cascade works because carbon monoxide molecules can be arranged on a copper surface in an energetically metastable configuration that can be triggered to cascade into a lower energy configuration, just as with toppling dominoes. The metastability is due to the weak repulsion between carbon monoxide molecules placed only one lattice spacing apart.

This situation is analogous to placing tennis balls next to each other in an egg carton. Since the tennis balls are slightly larger than the lattice spacing of the carton, they push against each other and can't nestle down into the hollows of the carton as deeply as they could if they were more widely separated.

Just as placing three tennis balls in a row of an egg carton is unstable, Heinrich and Lutz learned that a triad of carbon monoxide molecules arranged in a chevron-shaped pattern on the copper surface would spontaneously rearrange by the outward motion of the central molecule. They then designed ways to link pairs of molecules so the rearrangement of an initial chevron formed a new chevron, and so on, in a cascade of molecular motion.

What enables computation is that each cascade carries a single bit of information. By analogy, a toppled domino can be thought of as a logical "1," and a untoppled domino can be thought of as a logical "0." Similarly, a cascaded or non-cascaded molecular array can represent a logical "1" or "0," respectively.

The logic AND and OR operations and other features needed for complex circuits are created by cleverly designed intersections of two cascades. Heinrich and Lutz designed molecular arrangements that acted as crossovers (allowing two cascade paths to cross over each other) and fanouts (splitting one cascade into two or more paths).

These molecule cascades are currently assembled by moving one molecule at a time using an ultra-high-vacuum, low-temperature scanning tunneling microscope (STM). It takes several hours to set up the most complicated cascades. Since there is no reset mechanism, these molecule cascades can only perform a calculation once. While these initial cascades rely on the motion of a molecule, Eigler envisions that it should be possible to make nanometer-scale cascades using other fundamental interactions, such as electron spin. Such cascades may also be resettable, allowing repeated calculations, similar to ordinary computer circuitry.

Other features of molecule cascades include:

Energy: An intriguing aspect of molecule cascades is their minuscule energy consumption. The three-input sorter is estimated to expend only 1 electron-volt of energy -- 100,000 times less than the equivalent semiconductor circuit.

Temperature: IBM's initial cascades were created and operated a 4-10 degrees above absolute zero. In their paper, the scientists show how cascades operate faster at higher temperatures.

Precision construction: IBM's molecule cascades were created by positioning carbon monoxide molecules one at a time, a lengthy process. Other cascade mechanisms may not need to be built so precisely.

Additional information

Cascade images, animations: HYPERLINK http://www.research.ibm.com/...

IBM's nanotechnology research projects: HYPERLINK http://www.research.ibm.com/...

Fact Sheet

Molecule Cascade Fact/Message sheet: (draft 10/21/02)

IBM researchers have built and operated the world's smallest working computer circuits using a radically new nanotechnology, called a molecule cascade.

In a molecule cascade, individual molecules move across an atomic surface like toppling dominoes. By creating a precise pattern of molecules, moving a single molecule initiates a cascade of molecule motions, just as toppling a single domino can cause a large pattern to fall in sequence.

The first molecule cascade used carbon monoxide molecules on a copper surface.

The IBM scientists used their low-temperature, high vacuum scanning tunneling microscope to move the iondividual molecule into the precise patterns needed to make the circuits..

IBM's molecule cascade circuits are some 260,000 times smaller than those used in today's most advanced semiconductor chips.

The most complex circuit they built -- a 12 x 17-nanometer three-input sorter -- is so small that nearly 40 million could fit onto the area spanned by a single human hair.

These structures are so small that even if traditional semiconductor technology continued to improve at today's Moore's Law pace -- doubling feature density every 2.5 years -- it would take 45 years to get down to these circuit dimensions.

Members of the scientific team are: Andreas Heinrich, Christopher Lutz, Jay Gupta and Donald Eigler of IBM's Almaden Research Center in San Jose, Calif.

First publication of the molecule cascade is in the Oct 24, 2002 Science Express, the online edition of the prestigious scientific journal Science Magazine.

This is a milestone in the quest for nanometer-scale computer circuitry. It is not only a novel way to do computation, but it is also the first time all of the components necessary for computation at the nanometer scale have been made, connected together and then made to compute.

This new technique for computation is another indicator of how atomic and molecular behavior differs on the nanoscale compared with the more familiar realm of bulk materials.

This molecule cascade and the quantum mirage that Eigler and colleagues discovered two years ago are intriguing examples of novel nanoscale computing and information-processing approaches.

The IBM scientists will continue research to find and develop nanometer-scale computing systems based on the cascade mechanism.

Current cascade performs a single computation and cannot be reset. Cascades using other atomic and molecular properties may be resettable.

Hans-Juergen Rehm
IBM Deutschland GmbH
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