|
Topic Name: A new technique for nanolithography
Category: Nanocharacterization
Research persons: Elisa Riedo,William P. King
Location: Georgia Institute of Technology :: Atlanta, Georgia 30332, United States
Details
Scientists at the Georgia Institute of Technology have developed a new
technique for nanolithography that is extremely fast and capable of being used
in a range of environments including air (outside a vacuum) and liquids.
Researchers have demonstrated the technique, known as thermochemical
nanolithography, as a proof of concept. The technique may allow industry to
produce a variety of nanopatterned structures, including nanocircuits, at a
speed and scale that could make their manufacture commercially viable. The
research, which has potential applications for fields ranging from the
electronics industry to nanofluidics to medicine, appeared earlier this year in
the journal Nano Letters.
The technique is surprisingly simple. Using an atomic force microscope (AFM),
researchers heat a silicon tip and run it over a thin polymer film. The heat
from the tip induces a chemical reaction at the surface of the film. This
reaction changes the film’s chemical reactivity and transforms it from a
hydrophobic substance to a hydrophilic one that can stick to other molecules.
The technique is extremely fast and can write at speeds faster than millimeters
per second. That’s orders of magnitude faster than the widely used dip-pen
nanolithography (DPN), which routinely clocks at a speed of 0.0001 millimeters
per second.
Using the new technique, researchers were able to pattern with dimensions down
to 12 nanometers in width in a variety of environments. Other techniques
typically require the addition of other chemicals to be transferred to the
surface or the presence of strong electric fields. TCNL doesn’t have these
requirements and can be used in humid environments outside a vacuum. By using an
array of AFM tips developed by IBM, TCNL also has the potential to be massively
scalable, allowing users to independently draw features with thousands of tips
at a time rather than just one.
“Thermochemical nanolithography is a rapid and versatile technique that puts us
much closer to achieving the speeds required for commercial applications,” said
Elisa Riedo, assistant professor in Georgia Tech’s School of Physics. “Because
we’re not transferring any materials from the AFM tip to the polymer surface (we
are only heating it to change its chemical structure) this method can be
intrinsically faster than other techniques.”
It’s the heated AFM tips that are one key to the new technique. Designed and
fabricated by a group led by William King at the University of Illinois, the
tips can reach temperatures hotter than 1,000 degrees Celsius. They can also be
repeatedly heated and cooled 1 million times per second.
“The heated tip is the world’s smallest controllable heat source,” said King.
TCNL is also tunable. By varying the amount of heat, the speed and the distance
of the tip to the polymer, researchers can introduce topographical changes or
modulate the range of chemical changes produced in the material.
“By changing the chemistry of the polymer, we’ve shown that we can selectively
attach new substances, like metal ions or dyes to the patterned regions of the
film in order to greatly increase the technique’s functionality,” said Seth
Marder, professor in Tech’s School of Chemistry and Biochemistry and director of
the Center for Organic Photonics and Electronics. Marder’s group developed the
thermally switchable polymers used in this study.
“We expect thermochemical nanolithography to be widely adopted because it’s
conceptually simple and can be broadly applied,” said Marder. “The scope is
limited only by one’s imagination to develop new chemistries and applications.”
For nanolithography to be commercially viable, it must be able to write at high
speeds, be used in a variety of environments and write on a variety of
materials. While the technique demonstrated here doesn’t yet allow writing at
the centimeters per second rate that would be ideal, it does put researchers
much closer to the goal than previous techniques. Once perfected,
nanolithography could be used to draw nanocircuits for the electronics industry,
create nanochannels for nanofluidics devices or be adapted for drug delivery or
biosensing technologies.
About The Researchers:
Elisa Riedo
Assistant Professor, School of Physics
Adjunct Professor, School of Chemistry and BioChemistry
Ph.D. Physics 2000, University of Milano, Italy
Phone: (404) 894-6580
Room: N107
EMail: elisa.riedo [at] physics.gatech.edu
Fields of Interest ■
Nano-confined Liquids: Physics and chemistry of liquids when confined in nano-spaces.
Origin of hydrophobic forces.
Nanotribology: Friction and adhesion forces at the nanoscale.
NanoBioMechanics: Elasticity, plasticity and mechanical properties of nano-objects
from nanotubes to DNA.
Nano-patterning of chemical modified surfaces
■ Selected Awards, Honors, and Societies ■
Member of the American Physical Society, American Chemical Society, + Material
Research Society
November 2005: Selected as Highly Creative Researcher in Nanoscience and
Nanotechnology for the “Project on Creativity Capabilities and the Promotion of
Highly Innovative Research” (CREA), a joint USA/European endeavor.
August 2002: Best Poster, Gordon International Conference Tribology.
June 1999: Best Students Grant Award 1998-99 from ESRF, Grenoble.
Nov. 1995: Physics Degree Summa cum Laude.
William P. King
Kritzer Faculty Scholar
Associate Professor
Office: 4409 Mechanical Engineering Laboratory
Mailing Address:
4409 Mechanical Engineering Laboratory
1206 West Green Street, MC-244
Urbana, IL 61801
Telephone:217-244-3864
Fax:217-244-9956
Web Site:http://mechse.uiuc.edu/research/wpk/
Email:wpk@uiuc.edu
Awards & Professional Societies
Honors and Awards:
IBM Graduate Research Fellow, 2000-2002
National Science Foundation CAREER Award, 2003-2008
University of Dayton School of Engineering Outstanding Alumni Award, 2004
Invited Participant, National Academy of Sciences Keck Future Conference on
Nanobiotechnology, 2004
Georiga Institute of Technology Class of 1969 Teaching Fellow, 2005-2006
Department of Energy Defense Programs Early Career Award for Scientist and
Engineers, 2005-2010
Presidential Early Career Award for Scientist and Engineers (PE CASE), 2005-2010
Society of Manufacturing Engineers International Branimir F. von Turkovich
Outstanding Young Manufacturing Engineer Award, 2006
Invited Participant, 2006 US-Japan Young Researchers Exchange Program for
Nanotechnology and Nanomanufacturing , 2006
TR35 - Technology Review's list of the most innovative people under the age of
35, 2006
Funded:
The research was supported by the National Science
Foundation’s Center for Materials and
Devices for Information Technology Research, the
U.S. Department of Energy, the National
Science Foundation, the Georgia
Institute of Technology Research Foundation, the GT College of Sciences
Cutting Edge Research Award and ONR Nanoelectronics. In addition to Riedo,
Marder and King, the interdisciplinary research team consisted of Robert
Szoszkiewicz, Takashi Okada, Simon Jones and Tai-De Li from Georgia Tech.
In The Images:
1.Elisa Riedo
2.An animated look at how DPN works (not to scale).
3.An animated look at how thermochemical nanolithography works.
4.The initials for the Georgia Institute of Technology written with the
thermochemical nanolithography technique. (Image: Georgia Tech)
|
