Fwd: On the tube

From: Michael M. Butler (mmb@spies.com)
Date: Thu May 08 2003 - 22:31:55 MDT

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    > ON THE TUBE
    >
    > May 8th 2003
    >> From The Economist print edition
    > http://www.economist.com/science/displayStory.cfm?story_id=1763552
    >
    >
    >
    > A new type of computer memory uses carbon, rather than silicon
    >
    > WAITING for a computer to turn on is a nuisance. That is why
    > manufacturers
    > have been trying to create ³non-volatile² memories. These would be fast,
    > like the random-access memory (RAM) chips that are currently used for
    > often-accessed memory, but they would also continue to store information
    > even without power, like hard drives, which are too slow to use except
    > for
    > long-term storage.
    >
    > Several technologies have been competing to become the standard for fast,
    > non-volatile memory. The best known is magnetic RAM, which IBM and
    > Motorola
    > are touting. Others are based on polymers or on strange-sounding metal
    > alloys called chalcogenides that change shape when an electric charge is
    > applied to them. But there is now a new entrant to the field: carbon.
    >
    > Carbon comes in many forms. Diamonds and graphite are two of the most
    > familiar ones. A less familiar variety is the nanotube, also known as a
    > ³buckytube² after Richard Buckminster Fuller, whose geodesic domes have a
    > framework similar to the arrangement of the atoms in a nanotube.
    > Nanotubes
    > consist of a cylindrical array of carbon atoms whose diameter is only
    > about
    > 1 nanometre (a billionth of a metre). If Nantero, a firm based in Woburn,
    > Massachusetts, proves correct, such tubes will soon be an integral part
    > of
    > computer memories.
    >
    > Nantero's memory chips consist of billions of nanotubes, each a few
    > hundred
    > nanometres long, suspended from a silicon wafer. Another wafer sits about
    > 100 nanometres below the first. Because the nanotubes that Nantero uses
    > conduct electricity, a small electric charge at one point on the second
    > wafer will draw several dozen nanotubes towards it. Once they are there,
    > they stay there. That is because they are bound by Van der Waals
    > forces‹intermolecular bonds that do not depend on external power for
    > their
    > maintenance. An additional application of current, however, will release
    > the
    > nanotubes. This means that a group of a few dozen nanotubes can act as a
    > memory element, storing a single bit (either a one or a zero) of the
    > binary
    > code that computers use to operate. If the connection between the wafers
    > is
    > live at a particular point, the bit represented is a one. If not, it is a
    > zero.
    >
    > If nanotubes were not so small, this would not be a big deal. Because
    > they
    > are, though, Nantero's technology can already achieve a data density
    > considerably higher than existing RAMs. And because the wafers are so
    > close
    > together, those data can move rapidly from place to place. Nantero's new
    > memory can read or write a bit in as little as half a nanosecond
    > (billionth
    > of a second). The best RAM chips, by contrast, need ten nanoseconds to
    > perform a similar operation.
    >
    > At the moment, Nantero has only a working prototype. But the firm aims to
    > have memories on the market within a year. It thinks it will be able to
    > tool
    > up for commercial production quickly, because the fabrication technique
    > it
    > uses, though novel, relies on standard semiconductor-making technology.
    >
    > The main difficulty faced by others who have tried to go down the
    > buckytube
    > route is getting the tubes to align with each other when they are hung
    > from
    > the first wafer. Until now, the approach has been to try to grow all of
    > the
    > tubes in the correct orientation to start with. But Nantero's founders
    > came
    > up with a simpler, if less elegant, solution. They use established
    > lithographic techniques to get rid of tubes that are pointing in the
    > wrong
    > direction by zapping them with an electron beam. That leaves only those
    > that
    > are hanging down towards the opposite wafer.
    >
    > Though the recent chip is certainly impressive, the reason for getting
    > excited about Nantero is not so much the present as the future. Unlike
    > silicon, which is pushing against its physical limitations, carbon-
    > nanotube
    > technology is in its infancy. Greg Schmergel, Nantero's boss, says that
    > within the next few years the firm's engineers may be able to achieve
    > data
    > densities of a trillion bits per square centimetre (more than 1,000 times
    > that available on existing RAM) and it will be possible to read those
    > memories 100 times faster than can be done at the moment. The days of
    > silicon-based memory may be numbered.
    >
    >
    >
    >
    >

    -- 
    I am not here to have an argument. I am here as part of a civilization. 
    Sometimes I forget.
    


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