November 1, 1999
Computer Scientists Are Poised for Revolution on a Tiny Scale

SAN FRANCISCO -- Scientists at a variety of elite
laboratories around
the country are sharing a growing sense that they are
on the brink of a
new era in digital electronics. It will usher in a world of
circuits no more than
a few atoms wide, with a potential impact on computing, in
terms of speed
and memory, that may be too profound to fathom.

It was only in July that a group of researchers at
Hewlett-Packard and the
University of California at Los Angeles reported that they
had successfully
fashioned rudimentary electronic logic gates -- a basic
component of
computing -- that were the thickness of a single molecule.
Now other groups
are preparing to announce that they have succeeded in
creating other basic
computing components at this ultramicroscopic scale, known
as molecular
electronics.

Researchers at Yale and Rice Universities, for
example, plan to report in the journal Science in
a few weeks that they have taken an important
step past the Hewlett-UCLA work. In the July
demonstration, the molecular gate could be
made to move into open or shut positions, but
could not be switched back again. But the
Yale-Rice team says it has created
molecular-scale switches that can be repeatedly
opened and shut -- a necessary step in
representing zeros and ones, the basic binary
signals used in the circuitry of digital transistors.

            And now Hewlett-Packard scientists say they
            have recently taken an important step toward
            creating rows of conductive wires that are less
            than a dozen atoms across -- a crucial part of
            hooking together the molecule-sized switches
            that could one day result in computers vastly
            faster than today's.

            The rapid sequence of breakthroughs is giving the
researchers a new sense
            of confidence. "We're on the scent, and we know the fox is
out there," said
            Stan Williams, a Hewlett-Packard physicist who is a pioneer
in molecular
            electronics.

            According to the buzz in this research community, meanwhile,
other
            laboratories are making progress on a number of fronts,
working under
            top-secret conditions. One of these labs is said to be
working on a molecular
            device capable of holding random-access memory, or RAM.

            If molecular memory devices could be constructed, they might
offer vast
            storage capabilities for just pennies in cost. One near-term
application might
            be to permanently store an entire DVD-quality movie in a
space much smaller
            than a conventional semiconductor chip.

            As an applied science, molecular electronics would begin at
a minute scale far
            beyond the theoretical boundaries of the conventional
technology of silicon
            transistors.

            Today's silicon-based
            microelectronic devices have a
            minimum size between electrical
            components of 0.18 micron
            (about one-thousandth the
            thickness of a human hair) and
            could potentially go as small as
            0.10 micron. That would be
            100-billionths of a meter, or 100
            nanometers.

            But in molecular electronics, the
            smallest components may be
            able to shrink to one-hundredth
            that size -- a single nanometer.
            The difference could mean chips exponentially more powerful
than anything
            of a comparable size today or computing devices unimaginably
tiny by
            contemporary standards.

            The recent rapid pace of advance has led to a palpable sense
of mission
            among a small group of physicists, chemists and computer
designers, who
            until recently were viewed as impractical dreamers by much
of the computer
            industry.

            "In two to five years, you will begin to see functioning
circuits which are of
            recognizable utility," said John Ellenbogen, a molecular
electronics researcher
            at Mitre Corp., a research center for the military and
private industry.

            Such optimism leads a number of researchers to believe that
rapidly
            cascading advances in molecular-scale science may soon
constitute what
            economists refer to as a disruptive technology -- one that
changes basic
            industrial assumptions, just as the transistor did in
replacing the vacuum tube
            during the 1950s, and as integrated circuits overtook
individual transistors
            during the 1960s. Some molecular electronics researchers
envision an entirely
            new industry, perhaps within the next decade.

            The consequences of such a revolution would be immense and
possibly
            destabilizing for the world's semiconductor industry.
Although the chip
            industry now believes that it sees a path at least until
2014 for making
            ever-smaller solid-state silicon devices, the cost of the
manufacturing
            systems needed to make the chips is enormous -- and
continuing to mount
            with each new chip generation.

            Today's semiconductor chips are made in multibillion-dollar
fabrication plants
            -- or "fabs" -- that use light waves to etch successive
layers of circuitry on a
            silicon substrate. It is an expensive process, in part
because of the high cost
            of creating and maintaining the "clean rooms" required for
avoiding
            contamination by dust. But researchers in molecular
electronics are optimistic
            that they will be able to use much less finicky methods by
creating chemical
            reactions that "self-assemble" vast numbers of
molecular-scale circuits at
            infinitesimal cost.

            "This should scare the pants off anyone working in silicon,"
said Mark Reed,
            a Yale University chemist, who is co-author of the
forthcoming Science
            article and co-leader of a related memory project to be
announced Dec. 6 at
            the International Electron Device Meeting in Washington. "It
will be dirt
            cheap and it will create a discontinuity."

            A colleague in the field agrees. "If you can make computers
as easily as
            photographic film, then a lot of companies are going to be
wondering what
            they're doing with their $15 billion fabs," said James
Heath, a UCLA chemist
            who is part of the Pentagon-financed Hewlett-Packard-UCLA
research team
            that demonstrated molecular logic gates last summer.

            The vision of a new industry
            has captured government and
            corporate attention. The Clinton
            administration is now
            considering the possibility of a
            National Nanotechnology
            Initiative as early as next
            January to set up financing and
            help organize diverse research
            activities in nanotechnology -- a
            range of manufacturing
            technologies that begin at the
            scale of individual molecules.
            Moreover, a number of
            computer and semiconductor
            companies, led by Sun
            Microsystems and Motorola,
            have been quietly meeting with scientists to discuss the
formation of an
            industry consortium to seek commercial applications for
molecular
            electronics.

            And yet, researchers acknowledge that so far they have taken
only the first
            baby steps toward the larger challenge of building
molecular-scale
            computers. No one, for example, has figured out how to
interconnect billions
            and billions of molecular switches with wires 11 atoms in
diameter.

            "It feels like we're a year before the invention of the
transistor and we're
            asking: 'What does solid state look like?"' said Paul Saffo,
a researcher at the
            Institute for the Future who has tracked the development of
new
            technologies.

            And there is a general agreement that if such systems are to
be assembled
            into workable computers, it will require radically new
architectures alien to
            today's semiconductor-based computers.

            At Hewlett-Packard, at the Massachusetts Institute of
Technology's
            Laboratory of Computer Science and at Mitre, computer
scientists are
            beginning to explore computer architectures that are far
more fault-tolerant
            than today's microelectronic computers and whose structures
resemble
            biological systems.

            Manufacturing might involve assembling trillions of circuits
and then
            identifying and mapping out the bad ones -- much as faulty
sectors are
            declared off limits in today's disk drives.

            "We will try to program with what we've got," said James
Tour, a molecular
            scientist at Rice University. "It's a very biological
approach. Everyone's brain
            is the same, but the pathways are all unique."

            Much of the research financing in this field now comes from
the Pentagon's
            Defense Advanced Research Projects Agency. "We've built this
entire
            program on the idea of thinking differently," William
Warren, a program
            manager at the agency, said. "We don't want to be standing
on the shoulders
            of silicon."

            That is why the recent first steps toward eventual
self-sufficiency have
            created such excitement in the molecular computing research
community, a
            group that for years had a consistent vision but no
empirical results.

            "All of us were constantly on the defensive," Ellenbogen,
the Mitre
            researcher, recalled. "Although we believed in some rational
way this was the
            way to go, among ourselves we were continually forced to
reassure
            ourselves that we weren't crazy."


By JOHN MARKOFF
Copyright 1999 The New York Times Company
http://www.nytimes.com/library/tech/99/11/biztech/articles/01nano.html

janet paterson
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