Nanofabrication: Principles, Capabilities and Limits

442 Pages·2017·21.643 MB·English

by  Zheng Cui (auth.)

Zheng Cui
Nanofabrication
Principles, Capabilities and Limits
Second Edition
Nanofabrication
Zheng Cui
Nanofabrication
Principles, Capabilities and Limits
Second Edition
Zheng Cui
Suzhou Institute of Nano-Tech
and Nano-Nanobionics (SINANO)
Suzhou , China
ISBN 978-3-319-39359-9 ISBN 978-3-319-39361-2 (eBook)
DOI 10.1007/978-3-319-39361-2
Library of Congress Control Number: 2016943135
© Springer International Publishing Switzerland 2017
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Pref ace
It has been nearly 8 years since the fi rst edition of this book was published. I was
surprised as well as pleased to fi nd that people who are practicing on nanofabrica-
tion for their own applications still look for answers or acquire information from my
book. I knew this because I have been receiving my book royalty from Springer
every year in the last 8 years. The continued interests in my book from readers
across the globe prompted me to consider writing the second edition. I felt that I
owed readers an updated version of the book. The plan of writing the second edition
was hatched in early 2015. After a year of fi ghting with my busy working schedule
to squeeze out time to write, here fi nally is the second edition.
Looking back on the past 8 years, the development in nanofabrication technol-
ogy is clearly on two paths, the path towards mass manufacturing of structures/
devices particularly for integrated circuits (IC) and the path towards fabrication of
structures/devices for scientifi c research. On the IC manufacturing side, the technol-
ogy node of 32 nm was just demonstrated at the prototyping stage 8 years ago. Now
manufacturing of 10 nm ICs is in the preproduction stage. The progress was not
brought about by any revolutionary new technologies but by continuous refi ning of
the technologies already existing 8 years ago, such as multiple patterning with
193 nm deep UV photolithography. The nanofabrication processes for mass manu-
facturing of ICs have become highly specialized and hugely expensive. Only a
handful of companies and organizations across the globe can access these technolo-
gies. On the scientifi c research side, diversity and variety were the features of nano-
fabrication development. Anyone can invent a new trick to make something at
sub-100 nm scale in a lab. To understand this, one can just browse through the sea
of scientifi c publications from the past 8 years. Mentioning of nanofabrication has
been scattering all over the place. However, the fundamental techniques one can
fi nd in every nanofabrication lab are still various lithographic patterning and pattern
transfer processes, which is probably the reason that my book still has readers even
though it was published 8 years ago. With more and more nanofabrication facilities
set up in universities and research labs across the globe, nanofabrication becomes
more of a routine activity than a research fi eld. People learn nanofabrication
v
vi Preface
techniques because they need them as tools for their own specifi c applications. For
this reason, the second edition maintained the same structure as the fi rst edition but
added more basic information about nanofabrication, and at the same time included
some new developments that have happened in the last 8 years.
The second edition has expanded from 8 chapters to 11 chapters. The newly
added chapters are the splitting of “Nanofabrication by Charged beams” chapter
into two chapters (electron beam and ion beam) and splitting of “Nanoscale Pattern
transfer” chapter into two chapters (etching and deposition), so that they can be
described in more details. Nanofabrication by electron beam and by ion beam
deserves to be in separate chapters as they are the two most important patterning
processes in nanofabrication. Pattern transfers by etching and by deposition are also
of different distinctive features and are better introduced separately. There was no
mention of application aspect of nanofabrication in the fi rst edition. A new chapter
on application (Chap. 1 1) is therefore added. The addition of a chapter on applica-
tion would help readers to relate the nanofabrication techniques introduced in the
book to practical examples. With the aforementioned expansion, the second edition
ended up with 30 % more content compared to the fi rst edition. Apart from the
expansion, new developments and new data are added in each chapter for each of
the nanofabrication technique described so that readers will have the most updated
information. Because of the length limit of the book, many more new developments
may have been omitted. The information I have selected is based on my own judg-
ment to be the most signifi cant and will have a long-lasting infl uence in the future.
In the last 8 years, my own career also had a major change. I wrote the fi rst edi-
tion in Oxford, when I was working at the Rutherford Appleton Laboratory in the
UK. One year after the book was published, I left the UK and returned to China to
join the Suzhou Institute of Nanotech and Nanobionics (SINANO) which is one of
the research institutes within the Chinese Academy of Sciences. Since then, I
started a new direction in research, the printed electronics. I set up the research
center, called Printable Electronics Research Center (PERC), which was then the
fi rst of its kind in China. Printed electronics is to use the conventional printing
process to make electronic devices. Printing is an additive patterning process,
directly depositing electronic functional materials in pattern forms onto substrates.
Though the patterning is not in nanometer scale and cannot be categorized as nano-
fabrication literally, printing can deposit a variety of nanomaterials such as nanopar-
ticles, nanotubes, or nanowires into functional devices. These nanomaterials play
key roles in the devices because of their nanoscale properties. In this sense, printing
can be considered as an alternative nanofabrication technique. In fact, the second
edition of my book has a section on pattern formation by printing (Chap. 8 ) to
explain why printing can be called nanofabrication. In the last few years my
research team has used printing, in combination with a variety of nanomaterials-
based inks, to make thin fi lm transistors, transparent conductive electrodes, and
fl exible light emitting devices. We have recently published a book, “Printed
Electronics: Materials, Technologies and Applications” (Wiley, 2016), on the sub-
ject. I also conducted a research project funded by the National Science Foundation
of China (NSFC grant No. 91123034) as part of the NSFC’s Key Program on
Preface vii
Nanomanufacturing in the last 4 years. The central theme of the project is the fun-
damental study of nanomaterials printing. Another project funded through National
Key Basic Research Program of China (Grant No. 2015CB351900) was started last
year, which is again looking at printing fabrication of fl exible and stretchable elec-
tronic devices and integrated systems. Though my main focus is now on printed
electronics, I have never been out of touch with the nanofabrication fi eld. All the
research activities I and my team carried out were intimately related to microfabri-
cation and nanofabrication of some sort. I have also kept a watchful eye on any new
developments in nanofabrication in the last 8 years, which enabled me to gather the
most updated information for writing the second edition.
Finally, my sincere gratitude goes to the SINANO Institute, the Chinese Academy
of Sciences, and all funding bodies which gave me the opportunities, resources, and
the platform. I have achieved a great deal with my research team in the last 6 years
since I returned to China. The future is even brighter and I am looking forward to it.

Suzhou, China Zheng Cui
May 1, 2016
Preface to the First Edition
T he idea of writing a book focusing on nanofabrication came after I gave a series of
lectures in 2007. First I was invited to give a lecture at the Nanoelectronics Research
Centre in the Peking University, China, in January 2007. The title of my lecture was
“Nanofabrication: Capabilities and Limits.” Then I was invited to give a presenta-
tion with the same title at the UK Institute of Physics Conference on “Nanoelectronics-
Materials and Technologies” in February 2007. The audience, who were mostly
working on new nanoelectronic devices, was keen to know which technology they
could use to make the nanostructures they need. In April 2007, I was on a lecture
tour in Taiwan where I lectured at National Taiwan University, Taiwan National
Nanodevice Laboratory, and National Cheng-Kung University. Wherever I lectured,
researchers and students were showing great interest in nanofabrication technolo-
gies and concerned about their capabilities and limits. My collaboration with
researchers in China, particularly with the Institute of Physics, Chinese Academy of
Sciences, where a number of research groups are devoted to nanomaterials and
devices, has also exposed me to frequent questions such as what are the capabilities
and limits of various current nanofabrication technologies. Although I have pub-
lished a book, titled “Micro-Nanofabrication Technologies and Applications
(Springer, 2006), my previous book, including a number of other books published
so far, has not made clear which technologies can truly claim to be nanofabrication
technologies. The descriptions of nanostructure fabrication are often buried in those
of microstructure fabrication. It is apparent that a book on this subject is desirable.
I t is no surprise that nanofabrication is drawing widespread interest, as nanotech-
nology has been a buzz word in the last few years across the global. Not only the
traditional physical science community is drawn into nanotechnology, researchers
in chemistry, medicine, biology, energy, and environment sciences are all becoming
interested in nanotechnology. Though nanoscience and nanotechnology are broadly
defi ned as research and exploitation of structures and systems at sub-100 nm dimen-
sion, the distinction between microfabrication and nanofabrication is not too obvi-
ous. Many traditional technologies for fabricating microscale structures are also
ix
x Preface to the First Edition
capable of making sub-100 nm structures, such as optical lithography, though many
advances in the optical lithography taking place over the years have made the
sub- 100 nm patterning possible. On the other hand, some of the technologies are
inherently “nano” rather than “micro,” such as fabrication based on scanning probes.
I have written the book especially with the sub-100 nm dimensional scale in mind,
and have selected only those technologies that are capable of making sub-100 nm
structures, or emphasized on the aspects of sub-100 nm structuring capabilities for
those technologies which have been traditionally for microfabrication. As the book
title suggested, I have described not only the nanofabrication capabilities for each of
the selected technology but also their limits which are either about the ultimate pat-
terning resolution or about the practicality as a fabrication technology.
N anofabrication is a multidisciplinary fi eld. A book in this nature is often written
by multiple authors. I was able to take on this task on my own because of my many
years working with various microfabrication and nanofabrication technologies. The
Central Microstructure Facility, Rutherford Appleton Laboratory, where I have
worked for 15 years, has been a place with sole job to provide micro- and nanofab-
rication solutions to researchers of many scientifi c disciplines. My connection with
the Laboratory of Microfabrication at the Institute of Physics, Chinese Academy of
Science, in the last 6 years as a visiting professor also has given me the opportunity
to work with many scientists in nanoscience and nanotechnology areas. Though I
cannot claim to be an expert in every nanofabrication technology described in the
book, my experience and insight into how a nanostructure should be made give me
the advantage of knowing which is a viable nanofabrication technology and which
is not. This helped me to select only those most appropriate technologies to be
included in the book. I hope the readers of the book should gain useful information
and advice when deciding which technology they should choose for their specifi c
applications.
I n the era when any information can be “googled” from the Internet, who would
still need a book? In fact more titles of professional books are published than ever
before. Though the Internet has provided the convenience of fi nding required infor-
mation at a stroke of keyboard, it still needs a trained eye to spot the correct and best
knowledge among the vast amount of information presented to someone. I must
admit that the Internet has helped me a great deal in gathering information and pre-
paring for the book. I hope that with my trained eyes I have fi ltered the useful infor-
mation through to my book. In addition the book has provided references, web
links, and explanation of terminologies, which should serve as a “street map” for
readers to fi nd their way through in the Internet “maze.”
M y gratitude goes to many of my colleagues and friends working at the Central
Microstructure Facility, Rutherford Appleton Laboratory, UK, at the Laboratory of
Microfabrication, the Institute of Physics, Chinese Academy of Sciences, and at the
Nanoelectronics Centre of Peking University, China, where I also serve as a visiting
Preface to the First Edition xi
professor. Many of their published work have been cited in the book, including
work published by many other experts in different fi elds. My fi nal thanks go to my
family, my wife Ling Wang who herself is also an experienced engineer working in
the micro- and nanofabrication fi eld, and my daughters, Helen and Katy, who have
supported me all along.
Oxford, UK Zheng Cui
25 July 2008