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Characterization and Stabilization of Atmospheric Pressure DC Microplasmas and Their Application to Thin Film Deposition

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Characterization and Stabilization of Atmospheric Pressure DC Microplasmas and Their Application to Thin Film Deposition Characterization and Stabilization of Atmospheric Pressure DC Microplasmas and their Application to Thin Film Deposition Volume 1 A Thesis Submitted to the Faculty of Drexel University by David Alexander Staack in partial fulfillment of the requirements for the degree of Doctor of Philosophy December 2008 ii Title © Copyright 2008 David A. Staack. All Rights Reserved. iii Acknowledgements I would like to convey my gratitude to both my advisers Prof. Bakhtier Farouk and Prof. Alexander Fridman whose help, support and guidance were appreciated throughout my graduate studies. Together their experience and expertise made my time at Drexel successful and enjoyable. I also would like to express my deep appreciation to the most dedicated Prof. Alexander Gutsol with whom I had pleasure to work with on this project. I feel thankful for the innovative research environment they created in our weekly meetings at the Drexel Plasma Institute. I additionally thank Prof. Nicholas Cernansky, Prof. Gennady Friedman and Prof. Yury Gogotsi for their valuable remarks and guidance in the various projects we have collaborated on. I am grateful for the financial support that I received during my graduate study especially from the NSF grant DMII-0423409, the Koerner Family Fellowship and the NSF-IGERT Program. I am thankful to the Department of Mechanical Engineering and Mechanics at Drexel University for providing an excellent graduate education and friendly environment. I would like to thank all my colleagues at DPI and in the CFF group for their camaraderie in the laboratory over the years; especially Tanvir Farouk. I am thankful to all my committee members and other professors for their constructive remarks and suggestions. I am very grateful to all my family and especially to my wife Andrea and son Nikolas for their patience and support. iv Table of Contents Title Page .............................................................................................. i Acknowledgements ............................................................................................ iii Table of Contents ............................................................................................ iv List of Tables ........................................................................................ xiii List of Figures .......................................................................................... xiv Abstract ........................................................................................ xxix 1. Introduction ..............................................................................................1 1.1.Background ..............................................................................................1 1.1.1. Plasmas ............................................................................................1 1.1.2. Plasma Processing and Plasma Enhanced Chemical Vapor Deposition ..............................................................................2 1.2.Thesis Statement .........................................................................................3 1.3.Motivation ..............................................................................................5 1.4.Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition .......6 1.5.Fundamental Study of Novel Atmospheric Pressure Microplasmas ...........7 1.6.Thesis Overview .........................................................................................8 2. Background and Literature Review ............................................................11 2.1.Summary ............................................................................................11 2.2.Introduction to Plasmas .............................................................................11 2.2.1. History ...........................................................................................12 v 2.2.2. Definition of a plasma ...................................................................14 2.2.3. Plasma in Nature ...........................................................................15 2.2.4. Laboratory Plasmas and Electrical Breakdown ............................16 2.2.5. Examples of common industrial/commercial plasma .................. 21 2.2.5.1. Low pressure discharges ...................................................21 2.2.5.2. Atmospheric pressure discharges ......................................22 2.2.6. Thermodynamics of Plasmas ........................................................23 2.2.6.1. Thermal Plasmas ...............................................................24 2.2.6.2. Non-thermal Plasma ..........................................................25 2.2.6.3. Energy Transfer in Non-Equilibrium Discharges .............27 2.2.6.4. Warm Discharges ..............................................................37 2.2.6.5. Plasma Thermal Instability ...............................................38 2.2.7. DC Glow Discharges ....................................................................39 2.2.7.1. V-I Curve ..........................................................................40 2.2.7.2. Structure ............................................................................43 2.2.8. RF CCP .........................................................................................47 2.2.9. Novel Atmospheric Pressure Plasmas ..........................................51 2.2.9.1. APPJ ..................................................................................52 2.2.9.2. Uniform DBD ...................................................................52 2.2.9.3. Microplasma .....................................................................53 2.2.10. Literature Review on Microplasmas .............................................54 2.3.Introduction to Plasma Processing and Thin Film Deposition .................57 2.3.1. Plasma Enhanced Chemical Vapor Deposition ............................57 vi 2.3.2. Thin and Thick film Deposition ....................................................59 2.3.3. Atmospheric pressure Deposition .................................................61 2.3.4. Literature review on Atmospheric Pressure Deposition ...............63 2.3.5. Classification of Amorphous Carbon Films .................................65 3. Initial Characterization of a DC Normal Glow Discharge ........................67 3.1.Context ............................................................................................67 3.2.Summary ............................................................................................67 3.3.Introduction ............................................................................................68 3.4.Experimental Setup ...................................................................................70 3.5.Experimental Results and Discussion .......................................................73 3.5.1. Discharge Visualization ................................................................73 3.5.2. Current-Voltage Characteristics ....................................................76 3.5.3. Breakdown Characteristics ...........................................................78 3.5.4. Glow to Arc Transition .................................................................81 3.5.5. Spectral Characteristics and Temperature Measurements ............85 3.5.6. Current Density Measurements .....................................................91 3.5.7. Electric Field Measurements .........................................................91 3.5.8. Discharge in Helium, Hydrogen and Argon .................................95 3.6.Analysis ............................................................................................97 3.6.1. Normal Glow Discharge ...............................................................97 3.6.2. Discharge Thermal Balance ........................................................100 3.6.3. Non-Equilibrium Discharge .........................................................101 3.6.4. Summary of Measured and Estimated Discharge Parameters ....102 vii 3.7.Chapter Conclusions ................................................................................103 4. Global Temperature Characteristics and Thermal Balance ..................106 4.1.Context ..........................................................................................106 4.2.Summary ..........................................................................................106 4.3.Introduction ..........................................................................................107 4.4.Experimental Setup .................................................................................109 4.5.Spectroscopic Model and Best Fit Temperatures ...................................113 4.6.Experimental Results and Discussion ................................................... 118 4.6.1. Spectral Sensitivity of Results .................................................. 120 4.6.2. Measurements of Electron temperature and Ion Density .......... 125 4.6.3. Temperature Characteristics and heat balance .......................... 129 4.7.Chapter Conclusions ............................................................................. 136 5. Spatially Resolved Temperature and Spectroscopic Measurements .. 138 5.1.Context ........................................................................................ 138 5.2.Summary ........................................................................................ 138
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