mechanisms and development of etch resistance for highly aromatic monomolecular etch masks

135 Pages·2007·3.85 MB·English

MECHANISMS AND DEVELOPMENT OF ETCH RESISTANCE
FOR HIGHLY AROMATIC MONOMOLECULAR ETCH MASKS –
TOWARDS MOLECULAR LITHOGRAPHY

A Dissertation
Presented to
The Academic Faculty

by

Erik Jonas Järvholm

In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy in the
School of Chemistry and Biochemistry

Georgia Institute of Technology
May 2007
MECHANISMS AND DEVELOPMENT OF ETCH RESISTANCE
FOR HIGHLY AROMATIC MONOMOLECULAR ETCH MASKS –
TOWARDS MOLECULAR LITHOGRAPHY

Approved by:

Dr. Laren M. Tolbert, Advisor Dr. Clifford L. Henderson
School of Chemistry and Biochemistry School of Chemical and Biomolecular
Georgia Institute of Technology Engineering
Georgia Institute of Technology

Dr. Andrew Lyon Dr. Dennis W. Hess
School of Chemistry and Biochemistry School of Chemical and Biomolecular
Georgia Institute of Technology Engineering
Georgia Institute of Technology

Dr. Lawrence A. Bottomley Dr. Mohan Srinivasarao
School of Chemistry and Biochemistry School of Polymer, Textile, & Fiber
Georgia Institute of Technology Engineering
Georgia Institute of Technology

Date Approved: April 6, 2007(cid:31)
I would like to dedicate this dissertation to my best friend and wife, Jessica. Without her I
would be nothing! Thank you for carrying my child. I would also like to dedicate this to
my Mother (Kerstin), late Father (Ulf), and Sister (Emma), their support and
understanding have been extremely important to me. I wish could see you guys more
often! Last but not least I would like to dedicate this to my Mother-In-Law (Mary) and
Father-In-Law (Fred) who has taken me into their family and made me feel like home
here in the USA.
ACKNOWLEDGEMENTS

First, I would like to thank my advisor, Dr. Laren M. Tolbert, for allowing me to
join his research group and for giving me the opportunity to do the research presented in
this dissertation. Since no research can be done alone and without guidance I also would
like to thank Dr. Jürgen Rühe (for inviting me to do research in Freiburg, Germany,
2003), Dr. Janusz Kowalik, Dr. Mohan Srinivasarao, Dr. Phillip First, Dr. Klaus Müllen,
Dr. Oswald Prucker, Dr. Clifford Henderson, and Dr. Dennis Hess for their invaluable
advice and discussion over the past few years.
Dr. Loretta Crow’s friendship and knowledge (not only scientific but also where
things are located in the lab, since I cannot find anything) has been extremely helpful and
she needs a special thanks. I also want to thank Dr. Christina Bauer for her interest in my
project but also for her help with both surface analysis and surface modifications. I would
also like to thank her for reading this thesis and helping me correct all grammatical and
weird wordings. I would like to thank Janusz who has helped me on a daily basis with
ideas and discussions. Of course I also want to thank the rest of the Tolbert research
group who has helped tremendously.
I also would like to thank all my collaborators Dr. Simon Jones for helping me
make the fullerene compounds, Nikhil Sharma for helping me with the necessary STM
analysis, Dr. Müllen for kindly giving the C96 molecules to me, Dr. Paul Sheehan for
trying dip-pen lithography with my compounds, Joel Pikarsky for training and helping
me with the AFM and SEM instruments, and the MIRC staff for helping me with all
processes in the cleanroom.
iv
I also would like to thank all my friends Jack, Colin, JP, Caroline, Kenneth, Matt,
Rahul, Henrik, Gavin, Stephen and many more, for listening about my work at Ga Tech
and also for playing golf and tennis with me to keep me sane.

v
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS iv
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF SYMBOLS AND ABBREVIATIONS xiv
SUMMARY xvii
CHAPTER
1 Introduction to Molecular Lithography 1
1.1 Historical Background 1
1.2 The Transistor 2
1.3 Photolithography 3
1.3.1 Materials 5
1.3.2 Coating 6
1.3.3 Exposure 6
1.3.4 Development 6
1.3.5 Etching 6
1.3.6 Removal or Stripping 7
1.3.7 Summary and Thoughts 7
1.4 Moore’s Law 8
1.5 The Rayleigh Equation 9
1.6 Molecular Lithography 11
1.7 The Ohnishi and Ring Parameter 13
1.8 Impact 14
v i
1.9 References 16
2 C96 – Discotic Molecules as Molecular Resist 19
2.1 Introduction 19
2.2 Experimental 22
2.2.1 Methods of Surface Analysis 22
2.2.2 Thermal Growth of SiO 25
2
2.2.3 The Benzophenone Photoprobe 25
2.2.4 Preparation of the Silane Benzophenone Monolayer 28
2.2.5 Materials 28
2.2.6 Synthesis of 4-Allyloxybenzophenone (ABP) 28
2.2.7 Synthesis of 4-(3’- Chlorodimethylsilyl)propyloxybenzophenone
(CSBP) 29
2.2.8 Immobilization of CSBP to a SiO Surface 30
2
2.2.9 Synthesis of C96 31
2.2.10 Covalent Attachment of C96 to the Silane Benzophenone Modified
Si/SiO Surface 33
2
2.2.11 Surface Morphology Study Depending on the C96 Concentration34
2.2.12 The Ohnishi and Ring Parameter for C96 37
2.2.13 Etching Using C96 as a Molecular Mask 39
2.2.14 Etch Rates for Various Plasmas 42
2.2.15 Polymer Buildup on C96 Structures 44
2.2.16 C96 as an Etchmak Using Different Plasmas 46
2.2.17 Removal of the C96 Monolayer Using Piranha Solution 52
2.2.18 Photolithography Using Plasma 3 57
2.3 Summary 58
2.4 References 60
vi i
3 Fullerene Containing Polymer Monolayers as Molecular Resists 63
3.1 Introduction 63
3.2 Experimental 64
3.2.1 Thermal Growth of SiO 65
2
3.2.2 Preparation and Synthesis of the Silane Benzophenone Monolayer65
3.2.3 Synthesis of ROMP polymer from 1-(3-(bicyclo[2.2.1]hept-5-en-2-
yl)hexyl-2-(3,4-dibutoxyphenyl-fulleropyrrolidine 65
3.2.4 The Ohnishi and Ring Parameter for BDPF 68
3.2.5 Morphology of ROMP-BHHDPFP at Different Concentrations and
Coating Techniques 69
3.2.6 Etching Using ROMP-C60 as a Molecular Mask 72
3.2.7 Removal of the Organic Layer Post Etching Using either an Oxygen
Plasma or Piranha Solution 74
3.3 Summary and Conclusion 78
3.4 References 80
4 Individual Fullerene Molecules In a Monolayer as Molecular Resist 81
4.1 Introduction 81
4.2 Experimental 82
4.2.1 The Ohnishi and Ring Parameter for MNFP 83
4.2.2 Preparation and Synthesis of the Silane Benzophenone Monolayer
84
4.2.3 Synthesis of 1-methyl-2-nonyl-[60]fulleropyrrolidine (MNFP) 84
4.2.4 Morphology of MNFP on Si 85
4.2.5 Etching using MNFP as a Molecular Mask 89
4.2.6 Removal of MNFP Using Piranha Solution 92
4.3 Summary and Conclusion 94
4.4 References 96
vi ii
5 Organization and Alignment of Materials Used for Molecular Lithography 98
5.1 Introduction 98
5.2 Experimental 98
5.2.1 Alignment of C96 98
5.2.2 Alignment of C96 to SWNT 99
5.2.3 Alignment of C96 to ROMP-C60 101
5.2.4 Alignment of C96 to an Ordered Monolayer of Teflon on SiO 102
2
5.2.5 Monolayer Alignment transfer of HBC using Zone-Casting
Technique using Benzopheone as a Photo Probe 104
5.2.6 Alignment of C96 using Rubbing Technique with Teflon 106
5.2.7 Dip-Pen Lithography with ROMP-C60 110
5.2.8 Alignment of MNFP and ROMP- C60 by Rubbing with Teflon
111
5.3 Summary and Conclusion 111
5.4 References 113
6 Summary, Conclusions, and Future Work
6.1 Summary and Conclusions 115
6.2 Future Work 116
6.3 References 117
ix
LIST OF TABLES
Page
Table 2.1: Etch rates of plasma 1, 2, 3, and 4 43
Table 2.2: Contact angle results for plasma 3 49
Table 2.3: Contact angle results for plasma 4 51
Table 3.1: Contact angle results for ROMP-C60 75
Table 4.1: Contact angle for MNFP covered surfaces 92

x