Rep
rint
in
g
Interview
Vol.
05
The Challenge of Manipulating Light Electron Beam Lithography System
Draws the Future
Susumu Noda
Professor of Graduate School of Engineering
and Faculty of Engineering, Kyoto University
“The acceleration of our research
is surely attributable to the
improvement of such systems.”
Susumu Noda
Professor of Graduate School of Engineering
and Faculty of Engineering, Kyoto University
After finishing the master’s course in the Graduate School of Engineering and Faculty
of Engineering, Kyoto University, Professor Noda joined Mitsubishi Electric Corporation.
In 1988, he assumed the post of an assistant in the Faculty of Engineering, Kyoto
University, an associate professor in 1992 and a professor in 2000. In the same year as
becoming a professor, he was awarded the 14th IBM Japan Science Prize for Research
on Semiconductor Photonic Crystals and Applications. Subsequently, Professor Noda
received a series of awards including the Commendation for Science and Technology
by the Minister of Education, Culture, Sports, Science and Technology in 2009, the
6th Reona Ezaki Award in 2009, the Medal with Purple Ribbon in 2014 and JSAP
Outstanding Achievement Award in 2015, etc.
The Challenge of Manipulating Light Electron Beam Lithography System Draws the Future
Optical chips, semiconductor laser innovations, thermal emission control and high-efficiency solar cells, etc…
Photonic crystals are without doubt innovative materials that catch the future.
Professor Susumu Noda of Kyoto University has led studies in this field since the very beginning
and continues to run toward an ambitious dream.
Ultra-modern Material Photonic Crystals
With the capacity to split, bend, store
and reinforce light, “photonic crystals”
manipulation of light, as can be done for
such technologies will ultimately realize
electrons.
today’s supercomputer performance in a
One example of possible applications
consumer-size computer.
of photonic crystals is an optic-wired
Photonic crystals are also expected to
computer with internal substrates made
trigger a revolution in semiconductor lasers.
are innovative materials that possess
with photonic crystals. For conventional
While semiconductor laser technology
great potential to manipulate light freely
substrates, data are transmitted by
has been significantly advanced in terms
of wavelength and time, it is left behind
and thereby bring about a great leap of
electrons between components such as
possibilities for electrical and electronic
CPU and memory. However, the velocity
other laser technologies including solid-
devices. As light has the advantages that
of electrons is limited and electrons
state lasers and gas lasers in terms of
it travels much faster than electrons and
necessarily generate heat, which has
power. Additionally, its advancement in
hardly attenuates even when traveling
been one of the major factors that prevent
power has been long overdue. If large-area
long distances, there have been diverse
an improvement in computer processing
coherent operations are fully realized by
attempts to marry it with electronics.
speed. Utilizing substrates made with
photonic crystal lasers, it is expected that
However, while flows of electrons can be
photonic crystals, however, data can be
high-power operations with consistently
manipulated freely with semiconductors,
carried by light between components.
high beam quality will be possible, which
for light, no such equivalent semiconductors
Technologies to store intense light at
will cause a new revolution in the field of
existed. Photonic crystals virtually serve as
one point by using photonic crystals
semiconductor lasers. Possible applications
“semiconductors for light” that allow for the
have already been invented. Advancing
thereof range from processing, automotive
and sensing industries to ignition lasers for
nuclear fusion. Its potential market size is
remarkably large.
Photonic crystals are also expected
to trigger renovation of thermal emission
technologies. Thermal emission herein
re f er s t o the phenomenon o f light
(electromagnetic wave) generation from
a heated object. For many years, this
phenomenon has been utilized as an
Fig.1: Three-dimensional image of a
light path through a photonic crystal
underlying principle of lamps and light
sources for analyses. In this sense, the sun
is also a thermal emitter , radiating light in
an extremely broad band from ultraviolet
light to infrared light. Similarly, general
410nm
415nm
415nm
420nm
410nm
nano-resonator
thermal emitters radiate a broad range of
light not needed for specific purposes and
this greatly degrades light use efficiency.
What if thermal emission from objects can
be converged into desired wavelengths
waveguide
and desired linewidths with no energy loss
and be controlled dynamically and at ultrahigh rates? It will realize high-efficiency and
high-rate infrared light sources for various
analysis purposes and significantly improve
efficiency of thermophotovoltaic power
generation system.
Fig.2: A two-dimensional pattern of orderly-aligned air-holes with “artificial defects”
applied. The portion indicated as “Nano-resonator” (between the dashed lines with 10
mm wider pore intervals) can confine light longer. The portion indicated as “Waveguide”
(its height is larger than that of the nano-resonator) serves to guide light from outside to
Structure to Manipulate
Light Freely
Light has wave-like characteristics, and
differences of wavelength in the visual light
range are represented as different colors.
The reason why sunlight and fluorescent
light look white to us is due to synthesis
of light in various wavelengths. A red
post looks red because the light reflected
from the post is red and the other light
is absorbed or transmissive. Reflection,
absorption and transmission of light are
determined by an object’s molecular and
surface structures. Photonic crystals are
meant to design and produce such micro
structures to freely control light reflection
(i.e. changing light direction) and light
resonance (i.e. reinforcing light).
The procedure to make the photonic
the nano-resonator. As pore diameter and intervals should be controlled in nanometers,
precision drawing by an electron beam lithography system is required.
crystals is simple. As in the case of
insulator.”
semiconductors, the primary material
Structures called “artificial defects” are
component is a silicon wafer (or an
more important. When air-holes of different
III-V compound semiconductor wafer).
sizes or shapes and/or sections with no air-
The procedure is as follows: First, use
holes are created on the pattern of orderly-
an electron beam to create orderly-
aligned pores, the presence of light is
aligned air-holes on a wafer. This brings
allowed in such sections, making it possible
air into the pores. Then a large number
to transmit or store light through the
of recurrent patterns with different
sections. These “defects” serve as cages
refraction indexes are created in between
of light. Therefore, it is possible to flexibly
semiconductor parts and reflection
control how light propagates by arranging
occurs at the boundaries. Consequently, it
the defects accordingly. (Fig.1 illustrates
causes a Bragg reflection phenomenon in
a three-dimensional view of an example
which light reflected from boundaries in a
photonic circuit on a photonic crystal
specific direction interferes constructively
wafer.) Also, if micro defects (including
and other light interferes destructively and
micro-variations of defect sizes) are made,
disappears, and results in a so-called “light
light will converge into the defects and only
light of wavelength(s) appropriate to the air-
research expenses. They were so poor
holes size will interfere constructively. Such
that some used empty sake bottles as
structures will realize light-storing memories
beakers,” he reflected.
for photonic circuits and micro laser
The Pursuit of Future
Standard Devices
After consistently dedicating himself to
devices. (Fig.2 shows a two-dimensional
The professor said photonic crystals
electron micrograph of optical waveguide
represented such a big dream that it
a paper he published in 2000 catapulted
and nano-resonator formed on a photonic
made him enthusiastic about continuing
Professor Noda into the limelight. The article
crystal wafer.)
the study in such difficult conditions.
demonstrated the feasibility of photonic
low-profile basic research for over 10 years,
crystal technology with the abundant fruits
Nonetheless, the air-hole diameter is as
“When I started the research, many
of his long-standing research, which were
even smaller than the size of a virus, and
researchers questioned its practical
substantial enough to involve a multitude
this means accuracy by nm is required
possibility and they believed it to be a
of researchers. Today, there are a number
for manufacturing. To achieve desired
mere fantasy. Even so, I still believed
of applied researches of photonic crystals
functions, air-hole locations must be
photonic crystals would realize key
aiming to generate tangible outcomes.
controlled in sub-nanometers and a highly
devices for the future if put into practice."
fine as approximately 200 nm, which is
A Prime Figure behind
Practical Applications of
Photonic Crystals
One of the most expected applications of
the technology is the aforementioned large-
precise machine is required.
Due to the shor tage of funds and
area coherent semiconductor laser. As of
immature nano-engineering technologies,
this writing, watt-class operations of high-
his research could not go beyond the
quality and high-power beam output with a
theoretical phase.
single chip have been successfully carried
out. Researchers expect that the world will
Susumu Noda, a Professor at Kyoto
A large part of the leap in his photonic
change when 10W operations are put into
University, has been actively engaged in
crystal research was a result of the
practice. Also, an application in solar cells
development of photonic crystals since
progressive development of devices
has attracted attention as a renewable
the 1980’s.
called electron beam lithography systems.
energy source. Existing solar cells can
After completing graduate school,
We can call this machine (photo on
absorb and convert only a part of visible
y oung Pro f ess or Noda joined the
right) “nano-printer” as it draws design
light into power so a large part of sunlight
Central Laboratory at Mitsubishi Electric
data developed by CAD, etc. on nano-
is abandoned. The themal emission control
Corporation and continued research on
materials by using an electron gun that
with photonic crystals (mentioned earlier),
laser technologies. Reaching a certain
emits electrons in the form of beams.
is expected to solve the issue in the future;
point of satisfaction in his research, he
This technology has been used as an
i.e. thermal emission control could improve
began exploring possibilities of next-
electron-emitting source of electron
power generation efficiency by allowing for
generation optical materials and focused
microscopy. JEOL went into the business
solar cell designs that emit light in a specific
his attention on photonic cr ystals.
of electron beam lithography systems in
band for the most efficient absorption by
Coincidentally, his former professor
1967 with its long-standing technologies
the cells and allow them to absorb most of
the sunlight.
offered him an assistant position at Kyoto
and experiences in electron microscopy
University and he decided to return to
〒196-8558 東京都昭島市武蔵野 3-1-2 business and improved the system’s
TEL:
(042)542-1111
) FAX: (042)546-3353
academia
for basic( 大代表
research.
performance step by step in accordance
the possibilities of such novel technologies,
東京事務所・グローバル営業推進本部
本社・昭島製作所
with the voices of researchers.
many researchers believe Professor Noda
本社・昭島製作所
Admiring his achievements that opened up
〒100-0004 東京都千代田区大手町
2-1-1 大手町野村ビル
13 階 〒196-8558
3-1-2 “At
that time,東京都昭島市武蔵野
Japan was at the
zenith of its
TEL:
(03)6262-3567
FAX:
(03)6262-3577
TEL:
(042)542-1111
( 大代表
) FAX: (042)546-3353
deserves the next Nobel Prize.
※ 東京事務所・グローバル営業推進本部
本誌は、弊社ウェブサイトのコンテンツを印刷用に再構成したものです。
locates the object and draws with great
environment
of private enterprises was
掲載の機関名・役職・装置外観などは、ウェブサイト掲載当時のものです。
〒100-0004 東京都千代田区大手町 2-1-1 大手町野村ビル 13 階 precision. The acceleration of our research
far
better
than
that
of
academia
because
TEL: (03)6262-3567 FAX: (03)6262-3577
“Practical use of photonic crystals is just
is surely attributable to the improvement
nurture the budding technologies to their
bubble economy. As such, the research
www.jeol.co.jp/products/interview/
university laboratories could, at best, only
“JEOL’s lithography system accurately
※ 本誌は、弊社ウェブサイトのコンテンツを印刷用に再構成したものです。
掲載の機関名・役職・装置外観などは、ウェブサイト掲載当時のものです。
of such systems.”
obtain
several millions of yens per year for
getting started. My mission is to steadily
full bloom,” he said.
www.jeol.co.jp/products/interview/
Main Office
3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
Electron Optics Business Promotion Department
MainBusiness
Office Promotion Division
Global
3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
13F, Ohtemachi Nomura Building
2-1-1 Ohtemachi, Chiyoda-ku, Tokyo 100-004 Japan
Electron
Optics Business
Promotion Department
TEL:
+81-3-6262-3567
FAX: +81-3-6262-3577
Global Business Promotion Division
※ This book edited the article carried in our web site for print.
13F, Ohtemachi Nomura Building
The agency's name, the post and the equipment out ward
2-1-1 Ohtemachi, Chiyoda-ku, Tokyo 100-004 Japan
appearance which appear on a thing, too in web site carrying.
TEL: +81-3-6262-3567 FAX: +81-3-6262-3577
www.jeol.co.jp/en/products/interview/
※ This book edited the article carried in our web site for print.
The agency's name, the post and the equipment out ward
appearance which appear on a thing, too in web site carrying.
No. Y3021A604C Printed in Japan, Pp