MADISON - In the time it takes to read this sentence, your fingernail will have
grown one nanometer. That's one-billionth of a meter and it represents the scale
at which electronics must be built if the march toward miniaturization is to
continue.
Reporting in the June 3 issue of the Journal Science,
an international team of researchers shows how control
over materials on this tiny scale can be extended
to create complex patterns important in the production
of nano-electronics.
About two years ago, a team led by University of
Wisconsin-Madison Chemical and Biological Engineering
Professor Paul Nealey, demonstrated a lithographic
technique for creating patterns in the chemistry
of polymeric materials used as templates for nano-manufacturing.
They deposited a film of block copolymers on a chemically
patterned surface such that the molecules arranged
themselves to replicate the underlying pattern without
imperfections.
That
technique works well for
creating templates that
are neatly ordered in periodic
arrays, explains Nealey,
who directs the NSF-funded
Nanoscale Science and Engineering
Center. "But one of the challenges
of nanofabrication is integrating these self-assembling
materials, that naturally form periodic structures,
into existing manufacturing strategies," he says.
Adds
Nealey: "Engineers create
microelectronics under
free-form design principles.
Not everything fits neatly
into an array. This new
technique directs the assembly
of blends of block copolymers
and homopolymers on chemically
nano-patterned substrates.
The result is the creation
of structures with non-regular
geometries. We've now potentially
harnessed the fine control
over structure dimensions, afforded by self-assembling
materials, to allow for the production of complex
nano-electronic devices."
That kind of control is critical if computer architects
are to continue advancing by Moore's Law. In 1965,
Gordon Moore noted the exponential growth in the
number of transistors per integrated circuit and
predicted the trend would continue. It has. About
every 18 months, the number of transistors in computer
chips doubles. By decreasing the size of these components
and, consequently, fitting more of them onto a single
chip, computer speed and power improves. But before
long, existing technology will run out of room.
Current manufacturing processes employing chemically
amplified lithography techniques achieve dimensions
as small as 50 to 70 nanometers, but that technology
might not be extendable as feature dimensions shrink
below 30 nanometers.
By merging the latest principles of lithography
and self-assembly block-copolymer techniques, researchers
at UW-Madison and the Paul Scherrer Institute in
Switzerland developed a hybrid approach that maximizes
the benefits and minimizes the limitations of each
approach to nano-manufacturing.
"These new self-assembly materials used in conjunction
with the most advanced exposure tools may enable
the extension of current manufacturing practices
to dimensions of 10 nanometers and less," says Chemical
and Biological Engineering graduate student and co-author
Mark Stoykovich.
The team includes Nealey, Stoykovich, graduate student
Erik Edwards, former postdoctoral researcher Sang
Ouk Kim, UW-Madison Chemical and Biological Engineering
Professor Juan de Pablo, UW Physics Associate Professor
Marcus Mueller, and Harun Solak of the Paul Scherrer
Institute in Switzerland. The group conducted its
work at the Center for NanoTechnology at UW-Madison's
Synchrotron Radiation Center.
It was funded in part by Semiconductor Research
Corporation and the National Science Foundation's
Nanoscale Science and Engineering Center.
- Jim Beal (608) 263-0611, jbeal@engr.wisc.edu |
