Flow Controlled Solvent Vapor Annealing of Block Copolymers for Lithographic Applications Kevin ...

192 Pages·2013·26.02 MB·English

Flow Controlled Solvent Vapor Annealing of Block
Copolymers for Lithographic Applications
by
Kevin Willy Gotrik
B.S. Engineering Physics
University of Wisconsin - Madison (2008)
Submitted to the Department of Materials Science and Engineering
in partial fulfillment of the requirements for the degree of
Doctor of Science in Materials Science and Engineering
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
June 2013
(cid:13)c Massachusetts Institute of Technology 2013. All rights reserved.
Author ..............................................................
Department of Materials Science and Engineering
May 17, 2013
Certified by..........................................................
Caroline A. Ross
Toyota Professor of Materials Science and Engineering
Thesis Supervisor
Accepted by .........................................................
Gerbrand Ceder
R. P. Simmons Professor of Materials Science and Engineering
Chair, Departmental Committee on Graduate Students
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Flow Controlled Solvent Vapor Annealing of Block
Copolymers for Lithographic Applications
by
Kevin Willy Gotrik
Submitted to the Department of Materials Science and Engineering
on May 17, 2013, in partial fulfillment of the
requirements for the degree of
Doctor of Science in Materials Science and Engineering
Abstract
Self-assembly of block copolymer thin-films may provide an inexpensive alternative
to patterning lithographic features below the resolution limits of traditional optical
methods. Block copolymers (BCPs) are polymers made of two or more distinct
monomer/block units that are covalently bonded. Due to their differences in surface
energy, the different blocks tend to phase segregate like oil and water; but because of
the covalent linkage, this segregation is practically limited to size scales ranging from
only a few nm to ≈ 100 nm. A thin film of a BCP can be used in much the same way
as a photoresist in the lithographic process, whereas a desired pattern morphology
can be obtained by etching one block away and leaving behind a self-assembled hard
mask for the underlying substrate.
After a thin film of BCP is coated onto a given substrate, the BCP must be given
an annealing step, where the disordered entangled polymer networks can be allowed
to diffuse and equilibrate into lower free energy configurations which result in periodic
patterns of micelles with different morphologies such as spheres, in/out of plane
cylinders, etc. This work explored the technique of solvent vapor annealing, where
organic solvents were allowed to interact with BCP thin films to facilitate annealing
and act as surrogates for the different BCP polymer blocks. This allowed for a wide
range of control over the BCP self-assembly (morphology, periodicity, etc.) for a
given molecular weight BCP. Additionally, by adding heat at critical times during the
self-assembly, time scales for solvent vapor enhanced self-assembly could be reduced
from hours to seconds making the prospects for this technology to become industrially
applicable more promising.
Thesis Supervisor: Caroline A. Ross
Title: Toyota Professor of Materials Science and Engineering
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Acknowledgments
I would like to start off by apologizing to anyone that I fail to acknowledge. I know
that a man is not an island unto himself; but rather, he is affected in some way by
every person he ever interacts with. I have been very fortunate to be able to grow
and mature in a surrounding where the people and communities have had a great and
positive influence on me. I hope that in my life I will be able to continue the work of
passing on these received gifts for the next generations to come.
I would like to thank my parents for raising me in a loving and caring household
where values such as compassion, self-sacrifice, faith, and hard work were instilled in
me. I would like to thank my siblings for being such great companions, and I look
forward to what the future brings. I would like to thank the community of educators
in my hometown of Gretna, NE where I spent twelve years learning how to learn.
I would like to thank my grandmother for putting up with me during my first two
years at the University of Wisconsin and my relatives there for the early morning
transportation on game days (Renee, Don, and Patti!). I would also like to thank the
UW for providing an opportunity to explore my research interests almost immediately
when I arrived there in 2003, and I would like to thank my mentors there: Prof.
Rob Carpick, Prof. Hal Evenson, Prof. Franz Himpsel, Prof. Wendy Crone and Dr.
Hongquan Jiang. I would like to thank those involved in helping me have successful
study abroad opportunities in Germany: Mary Bird, Dr. Tom Thersleff, and the staff
from DAAD’s RISE program.
I would like to thank my advisor, Prof. Caroline Ross for all of her guidance
throughout my thesis; without which, my time would not have been nearly as enjoyable.
I would like to thank all of the support staff who have been invaluable with helping
me find solutions to my problems: David Bono, Mike Tarkanian, James Daley, Mark
Mondol, and Dr. Shiahn Chen. I would like to thank some of my many mentors at
MIT: Prof. Karl Berggren, Prof. Jeff Grossman, and Prof. Michael Demkowicz. I
would like to thank the many friends and acquaintances that I met while at MIT and
especially those with whom I worked with on various projects. I would like to thank
the undergraduates of Conner4 who I was able to meet and mentor during my time
as a graduate resident tutor - I couldn’t have found a more pleasing place to reside.
I would like to thank my daughter Felicity (and now Eleanor!). I know she won’t
remember living here, but it brought joy to my day when I would come home to a
squealing one and a half year-old excited to see ’daddo.’ And lastly, I would like to
thank my best friend and loving wife Susan. She made every day a joy.
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Contents
1 Introduction and Motivation 27
1.1 Motivation and Outline of Thesis . . . . . . . . . . . . . . . . . . . . 27
1.2 Introduction to Block Copolymers . . . . . . . . . . . . . . . . . . . . 31
1.3 Annealing Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.3.1 Thermal Annealing . . . . . . . . . . . . . . . . . . . . . . . . 35
1.3.2 Solvent Vapor Annealing (SVA) . . . . . . . . . . . . . . . . . 37
1.4 Templated Self-Assembly . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.5 Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
1.5.1 Self-Consistent Mean Field Theory . . . . . . . . . . . . . . . 41
1.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2 Experimental Design and Methodology 49
2.1 Solvent Vapor Annealing Setups . . . . . . . . . . . . . . . . . . . . . 49
2.1.1 Basic Solvent Vapor Annealing . . . . . . . . . . . . . . . . . 51
2.1.2 Flow Controlled Solvent Vapor Annealing . . . . . . . . . . . 54
2.1.3 Solvothermal Annealing . . . . . . . . . . . . . . . . . . . . . 64
2.2 Experiment Operational Details . . . . . . . . . . . . . . . . . . . . . 67
2.2.1 Flow Controlled Solvent Vapor Annealing . . . . . . . . . . . 67
2.2.2 Solvothermal Annealing . . . . . . . . . . . . . . . . . . . . . 72
2.3 Digital Revolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
2.3.1 Mind Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 76
2.3.2 Multimedia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
2.3.3 Digital Library . . . . . . . . . . . . . . . . . . . . . . . . . . 78
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3 Basic Solvent Vapor Annealing Applications 81
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.2 Experimental Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
4 Flow Controlled Solvent Vapor Annealing 95
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.2 Experimental Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.4 Non-Random Two Liquid Model . . . . . . . . . . . . . . . . . . . . . 110
4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
5 Templated Self-Assembly 113
5.1 Enforcing Rectangular Symmetry . . . . . . . . . . . . . . . . . . . . 113
5.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
5.1.2 Experimental Methods . . . . . . . . . . . . . . . . . . . . . . 114
5.1.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . 116
5.1.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
5.2 3D Self-Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
5.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
5.2.2 Experimental Methods . . . . . . . . . . . . . . . . . . . . . . 125
5.2.3 SCFT Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 127
5.2.4 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . 132
5.2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
5.3 Removable Templates . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
5.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
5.3.2 Experimental Methods . . . . . . . . . . . . . . . . . . . . . . 143
5.3.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . 145
5.3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
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6 Solvothermal Annealing 153
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
6.2 Experimental Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 155
6.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 158
6.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
7 Conclusion and Future Work 169
7.1 Suggested Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . 170
7.1.1 Rapid Solvothermal Annealing . . . . . . . . . . . . . . . . . . 170
7.1.2 Controlling 3D Interconnects . . . . . . . . . . . . . . . . . . . 174
7.1.3 3D TEM Tomography . . . . . . . . . . . . . . . . . . . . . . 175
7.2 Looking Ahead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
A Supplementary Information 179
A.1 Self Consistent Mean Field Theory Code . . . . . . . . . . . . . . . . 179
A.2 Spectral Reflectometry . . . . . . . . . . . . . . . . . . . . . . . . . . 182
A.3 Mass Flow Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . 183
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