HP PROPOSE ALTERNATIVE TO TRANSISTORS
HP PROPOSE ALTERNATIVE TO TRANSISTORS
2005-02-06 at 10:37:00 am #10078
<>HP Propose Alternative to Transistors
SAN JOSE, Calif. (Feb. O5) – Challenging a basic tenet of
the semiconductor industry, researchers at Hewlett-Packard Co. have demonstrated
a technology that could replace the transistor as the fundamental building block
of all computers.
The devices, called crossbar latches, could be made so
small that thousands of them could fit across the diameter of a human hair,
enabling the high-tech industry to continue to build ever-smaller computing
devices that are less expensive than their predecessors.
For years, engineers have been able to pack more and more
smaller transistors onto a fingernail-size silicon chip. The rate of
integration, first predicted by Intel Corp. co-founder Gordon Moore in 1965, has
driven computer performance and prices for more than 30 years.
But the pace of Moore’s Law can’t continue forever, and the
high-tech industry has been scrambling to develop workarounds for the day –
expected in a decade or so – when transistor dimensions become too small for the
materials commonly used today.
“If we’re going to extend Moore’s Law for another several
decades, we’ve got to have an alternative strategy,” said Phil Kuekes, one of
the paper’s authors at HP Labs. “This is the final piece of the puzzle in what
HP has been putting together as such a strategy.”
The smallest features of today’s silicon-based transistors
are about 90 nanometers long, a nanometer being roughly one hundred-thousandth
the width of a human hair. The crossbar latch, by comparison, can work in a
space of about 2 to 3 nanometers.
The HP research, reported in Tuesday’s Journal of Applied
Physics, scraps the transistor entirely. In its place is basically a series of
platinum wires crossed opposite directions. At the junctions are molecules that
in the HP research happen to be steric acid.
“It’s metal and molecules. Nothing else,” Kuekes said.
“We’re getting away from the physics of silicon.”
Like in a transistor, an electrical signal that passes
through a crossbar latch is manipulated to perform logic functions. The latest
research shows that the technology also can be used for amplifying a signal,
allowing multiple functions to be applied.
“The power of this device is not when it’s by itself. It’s
when it glues together other pieces of logic,” said Duncan Stewart, another HP
Labs scientist and study co-author. “As soon as you’re able to do that, we call
that a computer.”
The researchers have not glued together multiple crossbar
latches, though they say it’s something they’re continuing to pursue. They
expect it to be commercially viable as early as 2012. The latches are formed
through a specialized stamping process for nano-sized imprints.
They also must persuade an industry built on transistors
that an alternative technology can be just as effective, said Stan Williams,
director of Quantum Science Research at HP Labs and another of the paper’s
“There came to be a mantra that you have to have
transistors to build computers,” he said. “A latch is a different way of
achieving that same function, but it turns out it has significant advantages
over a transistor.”
The crossbar latch not only works at a much smaller scale
than a transistor but also can do more, he added.
“In order to do the same thing that a latch can do, you
actually need many transistors,” Williams said.
In fact, other researchers have been focused on building
molecular transistors, which are much more challenging to build at such a small
scale, said James C. Ellenbogen, principal scientist in the Nanosystems Group at
the MITRE Corp.
“This may enable the field to proceed toward nanoprocessor
demonstrations and applications more rapidly and at lower cost,” he said.
It also could prove to be less expensive to build because
engineers can more easily work around defects that arise during manufacturing
than with those that occur during silicon fabrication, where defects are avoided
at great cost.
But crossbar latches aren’t going to replace today’s
silicon chips anytime soon. At first, they would likely be used for memory and
later for specialized devices. They also will have to integrate with today’s
silicon chips for the time being.
“Transistors will continue to be used for years to come
with conventional silicon circuits,” Kuekes said, “but this could someday
replace transistors in computers, just as transistors replaced vacuum tubes and
vacuum tubes replaced electromagnet relays before them.”