-
Created
the highest density electronically addressable memory
reported to date. The laboratory demonstration circuit, a
64-bit memory using molecular switches as active devices,
fits inside a square micron -- an area so tiny that more
than 1,000 of these circuits could fit on the end of a
single strand of a human hair. The bit density of the device
is more than 10 times greater than today's silicon memory
chips;
-
Combined,
for the first time, both memory and logic using rewritable,
non-volatile molecular-switch devices; and
"We
believe molecular electronics will push advances in future
computer technology far beyond the limits of silicon," said
Williams. "Capacity and performance could be extended
enormously by layering molecular-switch devices on conventional
silicon without the need for complex and expensive changes to
the base technology."
The
circuits (images of which are available at http://www.hpl.hp.com/about/media/stockholm/)
were fabricated using HP's patented cross-bar architecture
incorporating molecular switches.
First,
researchers made a master mold of eight parallel lines, each
only 40 nanometers wide. Then, in a three-step process,
researchers:
-
Pressed
the mold into a polymer layer on a silicon wafer to make
eight parallel "east-west" trenches, which they
then filled with platinum metal to form wires;
-
Deposited
a single layer of electronically switchable molecules on the
surface; and
-
Repeated
the first step, after rotating the mold 90 degrees to make
another eight wires, running "north-south," on top
of the molecular layer.
At
each of the 64 points where the top and bottom wires crossed,
the roughly 1,000 molecules sandwiched between them became a bit
of memory. A bit can be written by applying a voltage pulse to
set the molecules' electrical resistance and read by measuring
their resistance at a lower voltage.
"Using
a combination of optical and electron beam lithography, it took
about a day to create the master, which included 625 separate
memories connected to conventional wires so that we can
communicate with them," said Williams. "After that, it
took just a few minutes to make an imprint."
The
memories also proved to be both rewritable and non-volatile --
that is, they preserved information stored in them after the
voltage was removed. Today's DRAM chips do not have this
capability.
The
researchers also put logic in the same circuit by configuring
molecular-switch junctions to make a demultiplexer -- a logic
circuit that uses a small number of wires to address memory. A
demultiplexer is essential to make memories practical.
"This
is the first demonstration that molecular logic and memory can
work together on the same nanoscale circuits," said
Williams.
Four
U.S. patents have been awarded in connection with this work and
scientific papers are being submitted to reviewed technical
journals for publication.
The
HP Labs research team that fabricated and tested the memory was
led by senior scientist Yong Chen and included Douglas A. A.
Ohlberg, Xuema Li, Duncan Stewart, Tan Ha, Gun-Young Jung and
Hylke Wiersma.
About
HP
HP
is a leading global provider of products, technologies,
solutions and services to consumers and businesses. The
company's offerings span IT infrastructure, personal computing
and access devices, global services and imaging and printing. HP
completed its merger transaction involving Compaq Computer Corp.
on May 3, 2002. More information about HP is available at http://www.hp.com.
|
STOCKHOLM,
Sweden, Sept. 9, 2002 --
HP (NYSE:HPQ)
today announced dramatic new breakthroughs in molecular
electronics by scientists in HP Labs, the company's central
research facility.