view of the extreme ultraviolet lithography full-field step-and-scan
system. Inset shows a close-up of the 24- by 32-millimeter
fields that this technology can print on a silicon wafer.
MICROELECTRONICS permeate our lives. They are in our cars, our kitchen appliances,
and thousands of other products that drive our modern-day existence.
Now, researchers at Lawrence Livermore, Sandia, and Lawrence Berkeley
national laboratories have developed a system that will keep microchips
rolling off the line with ever-smaller features.
extreme ultraviolet lithography (EUVL) full-field step-and-scan
system is the first tool that demonstrates all of the key technologies
needed for production of next-generation microprocessors. This
fully integrated system prints 50-nanometer features—less
than half the size of those made by current production tools—and
it writes the full field size of the chip—24 by 32 millimeters.
The projection optical system, which was developed at Livermore,
is the first large-field diffraction-limited camera for extreme
ultraviolet (EUV) wavelengths and may rank as the most accurate
imaging system ever constructed.
it prints smaller features, the system produces chips that are
higher in density. That is, they can “do more” in
less space, which will dramatically improve the speed and memory
capacity of computer systems. Microchips with features smaller
than 50 nanometers may well lead to systems for facile speech recognition,
improved weather prediction, enhanced medical diagnostics, three-dimensional
image processing, microcontrollers for “intelligent” machinery,
and more powerful supercomputers for scientific and defense research.
Regina Soufli, one of Livermore’s principal investigators
on the multilaboratory team, says such applications will be possible
because the system embodies a set of groundbreaking technologies.
In fact, until a few years ago, the science and technology community
considered many of them impossible to develop.
team members (standing, from left): Eberhard Spiller, Russ
Hudyma, Rick Levesque, Chris Walton, Regina Soufli, John Taylor,
Sherry Baker, Mark Schmidt, Franklyn Snell, Layton Hale, Michael
Johnson, Nhan Nguyen, Don Phillion, Henry Chapman, Butch Bradsher;
(kneeling): Gary Sommargren, Ken Blaedel, Jim Folta, and Don
Making the Jump for Moore’s
several decades, integrated circuits have steadily gotten faster,
smaller, and cheaper. Circuit performance has basically doubled
every two years—a pace of development referred to as Moore’s
Law. This rapid development rate is primarily responsible for the
remarkable advances in computer technology that have occurred over
the past few decades.
fundamental physics laws on the diffraction of light are threatening
to put the brakes on this progress. Photolithography
uses light to print features onto a circuit substrate, which is
usually silicon. The wavelike nature of light makes it extremely
difficult to print images whose features have a resolution less than
the wavelength of the light being used. To print 100-nanometer
features—the current size for computer chips—manufacturers
have had to add expensive enhancements to lithographic systems.
The enhanced systems use light in the deep ultraviolet part of
the spectrum with wavelengths of
193 to 248 nanometers.
full-field step-and-scan system goes beyond deep ultraviolet into
the EUV part of the spectrum, using light with wavelengths of
about 13 nanometers—more than a factor of 10 shorter than the
wavelength of even the most aggressive deep ultraviolet system. The
current resolution for the EUVL system is 50 nanometers, but Soufli
says that a resolution of 20 nanometers will ultimately be possible.
She adds that such a fine resolution is not likely to be attained
with other semiconductor technologies for high-volume manufacturing.
Because it uses EUV light, the new system will also have a greater
depth of focus than systems using longer wavelengths, which will
guarantee more robust processing capabilities. In addition, the mask
patterns for imaging onto the silicon wafers can be relatively simple,
which eliminates the complex and expensive pattern modifications
that non-EUV systems use to enhance the resolution of the printing
the EUVL full-field step-and-scan system into reality for the next
Moore’s Law jump required the multilaboratory team
to rapidly develop several technologies. Many of these technologies
were thought to be too difficult or even impossible to develop in
time for EUVL to play a role in manufacturing.
example, the team developed highly accurate metrologies to fabricate
the system’s mirrors (see S&TR, October 1997,
Measures to Atomic Dimensions) because no existing
method came even close to measuring figure and smoothness with the
these measurements are accurate down to atomic dimensions. The team
also developed the world’s most precise multilayer reflective
coatings, which are necessary for EUVL optics (see S&TR,
October 2002, Stepping
Up to Extreme Lithography; October 1999, New
Deposition System for the Microchip Revolution), as well as a
clean, 13-nanometer light source with a high-power laser-produced
plasma. The source provides enough light for rapid scanning without
creating contaminants that would damage the system.
Since EUV radiation is absorbed by gases, new controls were needed
to ensure a suitable, ultrahigh-vacuum environment in which to operate
the system. The team developed magnetically levitated precision stages
compatible with the vacuum environment. Custom sensors were also
created that could operate in the EUV environment, and control hardware
and software were designed to provide full step-and-scan capabilities.
full-field step-and-scan system is the central element of the largest
Cooperative Research and Development Agreement (CRADA)
between the U.S. national laboratories and private industry. This
unprecedented CRADA is a 6-year, $250-million program, funded by
the EUV LLC, a consortium of six semiconductor manufacturers. The
system’s development was key in convincing the microelectronics
industry that EUV systems could follow deep ultraviolet systems as
the next-generation lithography technology for producing microelectronics.
In fact, Charles W. Gwyn, general manager of EUV LLC and a program
director at Intel, noted that the success of this system led EUVL
to be selected by international semiconductor organizations as the
best candidate technology for use with circuit features below 50
The EUVL system also has potential applications outside the semiconductor
manufacturing industry. Various nanotechnologies could benefit from
the large surface area that can be imaged with features smaller than
50 nanometers. Possibilities include photonic crystals, surface-acoustic-wave
detectors, and molecular electronic devices.
Set for the Future
With the success and acceptance of the system, EUVL now appears on
the road maps of all the major semiconductor manufacturers. Soufli
notes that subsequent versions of this system most likely will be
used to fabricate microelectronics that are 100 times faster than
those currently available. With Moore’s Law now in good shape
for well into the next decade, microelectronics will continue to
advance at the pace we have all come to take for granted for nearly
half a century.
Key Words: Cooperative Research and Development Agreement (CRADA),
extreme ultraviolet lithography (EUVL) full-field step-and-scan
system, EUV LLC, R&D 100 Award, semiconductor computer chips.
For further information contact Regina Soufli (925) 422-6013
(firstname.lastname@example.org) or John S. Taylor (925) 423-8227 (email@example.com).
a printer-friendly version of this article.