The Design, Fabrication, and Implications of a Solvothermal Vapor Annealing Chamber

82 Pages·2013·6.72 MB·English

The Design, Fabrication, and Implications of a
Solvothermal Vapor Annealing Chamber
by
Nathaniel R. Porter, Jr.
Submitted to the Department of Mechanical Engineering
ARCHIVES
in partial fulfillment of the requirements for the degree of
ASSACHUSETT , NS - UT
Bachelor of Science in Mechanical Engineering O7ECINOLOGY
JUL 3 1 2013
at the
RARIES
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
June 2013
© Massachusetts Institute of Technology 2013. All rights reserved.
Author ....... ./
.Iepartm t of Mechanyl Engineering
May 20, 2013
Al
~~~~1 j A
C ertified by .....................
David R. Wallace
Professor of Mechanical Engineering
Thesis Supervisor
Accepted by ...................
Annette Hosoi
Professor of Mechanical Engineering
Undergraduate Officer
2
The Design, Fabrication, and Implications of a Solvothermal
Vapor Annealing Chamber
by
Nathaniel R. Porter, Jr.
Submitted to the Department of Mechanical Engineering
on May 20, 2013, in partial fulfillment of the
requirements for the degree of
Bachelor of Science in Mechanical Engineering
Abstract
This thesis documents the design, fabrication, use, and benefits of a prototype alu-
minum solvothermal vapor annealing chamber which facilitates the self-assembly of
block copolymers (BCPs) on silicon wafers which are then used to generate nanoscale
patterns through the use of additive lithography. The chamber aids in the low-waste
production of research and development silicon wafers possessing unparalleled surface
resolution and feature density, by way of nanoscale lithography.
The concept of this chamber came out of a need by the MIT Department of Mate-
rials Science and Engineering for a faster and more controlled lithographic production
process. The chamber's design lends to a more simplistic, more durable, safer, and en-
vironmentally cleaner process than traditional custom-made laboratory instruments.
The prototype has the potential to become the standard apparatus for improving the
process of solvothermal vapor annealing as a custom-built single solution.
The chamber's design is intended to enable a safer, cleaner testing environment,
and provide increased control to the researcher by decoupling the temperature control
of the solvent, chamber, and sample holder. As a result, the chamber has the potential
to allow for a decrease in time for the production of annealed silicon wafers with more
dense features than current commercial processes enable.
The chamber not only meets the required specifications of the solvothermal vapor
annealing process, it also exceeds those expectations by allowing the researcher to
reduce overall solvent usage. It supports an internal gage pressure of at least one
atm psi and temperatures much greater than 100 degrees Celsius, both necessary
conditions for the annealing process. These benefits are the direct result of five
unique design characteristics.
The following unique characteristics of the solvent chamber design are:
a) A tightly toleranced sliding rod;
b) A precisely machined sample-specific sized holder;
c) A modular mount for the optical film measurement device;
d) A set of digitally controlled heaters;
3
e) A set of bolted and press-fitted pieces of aluminum, PTFE, quartz, and copper
serve to contain the highly flammable gases, toluene and heptane, normally present
in this process, safeguarding the researcher.
Although the chamber has not been fully tested in an end-to-end solvothermal
vapor annealing process, it demonstrates in self-testing to be a viable alternative and
promising solution for Kevin Gotrik, Ph.D. Candidate in the Materials Science and
Engineering.
There is potential for modifications based on user feedback and implementation.
Later prototypes could explore modifying the chamber geometry, wall thickness, and
sealing properties to achieve higher operating pressures and temperatures.
Thesis Supervisor: David R. Wallace
Title: Professor of Mechanical Engineering
4
Acknowledgments
As it turns out, college is not as simple as taking classes, writing papers, and finish-
ing projects. My time here at the great Massachusetts Institute of Technology has
exposed me to endless opportunities as well as a great number of individuals invested
in my success and happiness. This section is a tribute to all who have had a hand in
growing me to the individual I am now.
For this research and design opportunity, I would like to express my deep gratitude
to David R. Wallace, Professor of Mechanical Engineering, and Kevin Gotrik, Ph.D.
Candidate, my thesis advisor and intended customer, for their patient guidance, en-
lightening feedback, and steady encouragement throughout the development of this
topic. It has been a truly wonderful experience, and will undoubtedly be a point in
my life that I will warmly reflect on.
For my formal education and design experience, I formally thank the professors at
MIT that I had the pleasure of meeting, working with, and learning from. Through
their instruction, I have been exposed to the exciting world of Mechanical Engineering,
and have had the opportunity to explore my many, varied interests. Their work with
me has also awoken me to my passion for design, and instilled in me the ability to
problem solve at any level.
For the exposure to manufacturing technique, I am indebted to the Pappalardo
Laboratory staff and the technicians in the Laboratory for Manufacutring and Produc-
tivy. Through their encouragement and patience, I have had the pleasure of gaining
experience with everything from a mill, lathe, and drill, to 3D printers and circuit
construction. I would like to give special thanks to Richard R. Fenner, Stephen M.
Haberek, David A. Dow, and Patrick McAtamney for offering invaluable design and
manufacturing suggestions for the aide in fabrication of this artifact.
For the logistical enablement of this artifact and document, I sincerely appreciate
the efforts of Chevalley Duhart, Administrative Assistant to David R. Wallace, in
addition to Brandy Baker and Ellen Ferrick, Mechanical Engineering Undergraduate
Administrators. Ms. Duhart was a constant source of encouragement, and was able
5
to connect me with my thesis advisor at critical times. Both Brandy Baker and
Ellen Ferrick were supportive of my endeavors and created a special deadline for this
document based on my personal and educational schedule.
For the reviewing and editing of this thesis, I would like to acknoweldge David R.
Wallace, Professor of Mechanical Engineering, and my mentor, Darian C. Hendricks.
They were monumental resources for structuring my thoughts and developing the flow
of this document.
For the supplying of materials and fabrication, I thank Ed Moriarty, Edgerton
Center Instructor; McMaster-Carr Supply Company; Kevin Gotrik, Graduate Stu-
dent; the MIT Department of Materials Science Engineering; and Andrew Gallant,
MIT Central Machine Shop Supervisor. Mr. Moriarty provided me with material in
an emergency situation when I failed to order extra material from the McMaster-Carr
Supply Company. Mr. Gallant supported this project by ensuring that the welding I
needed was performed in time to complete the final prototype.
For personal and emotional support, especially during difficult times in my MIT
career, I thank my family, friends, the members of the MIT Gospel Choir, and my
coworkers at the Robert R. Taylor Network, Inc.
This document could not have been created and developed without these individ-
uals. I am incredibly grateful for their encouragment, support, and contributions.
6
Contents
Abstract 3
Acknowledgements 5
1 Background 15
2 Terms and Definitions 19
3 Introduction 21
3.1 M otivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Silicon and the Role in Technological Applications . . . . . . . . . . . 22
3.2.1 Optical Lithography and Masking . . . . . . . . . . . . . . . . 23
3.2.2 Electron Beam Lithography . . . . . . . . . . . . . . . . . . . 23
3.3 Recent Advancements in Nanolithography . . . . . . . . . . . . . . . 24
3.3.1 Solvothermal Vapor Annealing Process . . . . . . . . . . . . . 24
3.4 Existing Challenges in Nanolithography . . . . . . . . . . . . . . . . . 25
3.5 Problem Statement and Hypothesis . . . . . . . . . . . . . . . . . . . 25
3.6 Proposed Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.7 Research Questions and Approach . . . . . . . . . . . . . . . . . . . . 26
4 Solvothermal Vapor Annealing Process 29
4.1 T he P rocess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2 Process Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.3 Process Improvement: A New Chamber . . . . . . . . . . . . . . . . . 32
7
5 Design and Assembly of the Solvothermal Vapor Annealing Cham-
ber 33
5.1 Process and User Requirements with Chamber Design Specifications 33
5.2 Prototype 1.1: Chamber Design Schematics and Models . . . . . . . . 35
5.2.1 Full Assembly . . . . . . . . . . 35
5.2.2 Square Chamber . . . . . . . . 35
5.2.3 Sliding Rod . . . . . . . . . . . 37
5.2.4 Optic Mount . . . . . . . . . . 37
5.3 Prototype 1.5 . . . . . . . . . . . . . . 40
6 Fabrication and Experimental Testing of the Solvothermal Anneal-
ing Chamber 43
6.1 Manufacturing . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3
6.1.1 Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4
6.1.2 Sliding Rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
6.1.3 Optical Fixture . . . . . . . . . . . . . . . . . . . . . . . . . . 4 6
6.2 Assembly of Solvothermal Annealing Chamber . . . . . . . . . . . . . 48
6.3 Equipment: Quality Testing the Cham ber . . . . . . . . . . . . . . . 48
6.3.1 Waste Management . . . . . . . ................. 4 8
6.3.2 Optical Test . . . . . . . . . . . ................. 4 9
7 Solvothermal Vapor Annealing Process with the Prototype Cham-
ber 51
7.1 Setup of the Solvothermal Vapor Annealing Chamber . . . . . . . . . 51
7.2 Usage of the Solvothermal Vapor Annealing Chamber . . . . . . . . . 54
8 Conclusions 57
8.1 Findings and Observations . . . . . . . . . . . . . . . . . . . . . . . . 58
8.2 Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
8.3 O pen Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
8.4 Future Steps and Recommendations . . . . . . . . . . . . . . . . . . . 61
8
8.4.1 Design Chamber Enhancements . . . . . . . . . . . . . . . . . 61
8.4.2 Industrialization . . . . . . . . . . . . . . . . . . . . . . . . . 62
9 List of Figures 63
Bibliography 81
9
10