Discussion of EUV, ArF, Scalpel, and other technology..............
techweb.cmp.com
Posted: 3:00 p.m. EST, 3/13/98
Japan and Europe map plans for extreme-ultraviolet lithography
By David Lammers
KYOTO, Japan - Both Japan and the European Community are laying
the groundwork for separate cooperative-research programs into extreme
ultraviolet (EUV) lithography, according to participants at the inaugural
International Forum on Semiconductor Technology in Kyoto, Japan.
About 330 people discussed next-generation lithography and related issues
at the forum, which was organized by Japan's national Association for
Super-advanced Electronics Technology (ASET) research project.
The fledgling EUV efforts in Japan and Europe lag those of EUV LLC, an
Intel-backed operating which is extending EUV work started at the
Lawrence Livermore (Livermore, Calif.) and Sandia (Livermore) U.S.
national laboratories. To catch up, as many as 10 Japanese companies may
join a private EUV research project that now has three early participants:
Nikon Corp., Hitachi Ltd., and the Himeji Institute of Technology.
Professor Hiroo Kinoshita, a former NTT Corp. researcher, leads a small
EUV research effort at Himeji, located near Osaka.
Japan's government may put public funding behind the EUV project,
extending the work begun at ASET on argon-fluoride, electron beam and
proximity X-ray lithography. The EUV work may kick off as soon as next
year.
In Europe, ASM Lithography and its optics supplier Karl Zeiss have
started EUV research, and the European Community has given preliminary
approval to "a significant fraction" of a requested $75 million in funding,
said Michael Hatzakis, an advisor to the Institute of Microelectronics in
Greece. Hatzakis, a retired electron-beam researcher for IBM, evaluated
the EUV proposal.
In a separate presentation at the forum, Gerhard Gross, a Siemens AG
research manager, said the European "cluster project on future lithography"
has started preliminary EUV work, along with investigations into Ion
Projection Lithography and direct-write electron-beam lithography. After
about a year, the three approaches will be evaluated and a decision will be
made about future directions of the research, he said.
Naomichi Abe, a Fujitsu Ltd. lithography manager, said he personally
supports EUV as a promising approach. Abe said EUV relies on reflective
optics - polished mirrors - rather than the increasingly complex lenses
used in refractive optics. Also, the EUV particles are not charged when
they hit the wafer, another reason EUV research is gaining support.
However, he cautioned that the reflective masks required for EUV
lithography are "very complicated."
Still in its infancy
Compared with the relatively mature X-ray lithography, the EUV approach
is in its infancy. However, the short wavelength of the light holds out the
promise that patterns in the 0.05-micron realm and beyond may be
possible, using relatively simple optics and a 5:1 reduction-mask scheme.
Taro Okabe, executive director of the Semiconductor Industry Research
Institute of Japan, said an EUV project is being discussed in Japan, but
emphasized "it is only in the talking stage now. You can't really say that a
project is being officially planned now."
One lithography expert said Japan and Europe must support EUV research
in order to gather their own intellectual property, thereby earning enough
bargaining chips to make an exchange of information with EUV LLC a
tenable scenario.
U.S. participants at the forum said that the level of EUV research in Japan
and Europe "is very limited compared with the EUV LLC," but that the
basic technical strengths in Japan and Europe will ensure gradual progress.
U.S. companies involved in the mirror-making and coating processes now
being developed in the EUV LLC program have a commercial motivation
to sell their products abroad. Japanese companies will bring their own skills
to the EUV problem: Matsushita Electric Industrial and Canon Inc. are
co-developing mirror-polishing technology.
Richard Freeman, deputy associate director at the Lawrence Livermore
National Laboratory, said a number of EUV-related challenges -
problems that seemed intractable a few years ago - "have been put to
bed," including interferometry, and a way to avoid argon contamination on
the surface of the mirrors. Other challenges will be solved soon, Freeman
said, including simpler methods of creating the 13-nm-wavelength light,
manufacturing the aspheric mirrors and precisely coating the optics. An
optimized resist chemistry suitable to EUV light also must be worked out.
Argon fluoride for 0.10 micron
More process engineers - but certainly not all - are becoming confident
that Argon fluoride-based deep ultraviolet light at 193 nm can be used for
0.10-micron patterning, albeit with expensive phase-shift masks and optics.
Several participants at the Kyoto forum said that for the 0.10-micron
lithography, ArF-based steppers can be used in a mix-and-match
approach with critical mask layers written by means of X-ray, direct-write
electron beam or Scalpel, the scanned E-beam approach being developed
primarily within Bell Labs, the research arm of Lucent Technologies.
Several Japanese companies are expected to join a 10-company
consortium backing Scalpel, said Lloyd Harriott, director of the Scalpel
project at Bell Labs (Murray Hill, N.J.).
"We will announce the 10 companies very soon, after all the contracts are
signed," Harriott said. "There are several Japanese participants, a Korean
company, but, unfortunately, no European participants at this time. The
majority of consortium members are U.S. semiconductor manufacturers."
Hajime Sasaki, senior executive vice president of NEC Corp., said one
attraction of Scalpel is that the self-contained consortium can deal with the
intellectual property (IP) issue - a topic that arose repeatedly at the forum
- fairly easily. NEC and many other companies have patent
cross-licensing agreements with Lucent Technologies. Harriott said that
even though Scalpel has benefited from government support, the formation
of an international consortium will not pose IP issues. |
