Volume 1
List of Contributors .................................... XXVII
1 Characteristics of Low-Temperature Plasmas Under
Nonthermal Conditions - A Short Summary ..................... 1
Alfred Rutscher
1.1 Introduction ................................................ 1
1.1.1 Definition ............................................ 1
1.1.2 Types of Plasmas ...................................... 2
1.2 Starting Point for Modeling the Plasma State ................ 2
1.2.1 Single-Particle Trajectories .......................... 2
1.2.2 Kinetic and Statistical Theory ........................ 2
1.2.3 Hydrodynamic Approximation ............................ 3
1.3 The Role of Charge Carriers ................................. 3
1.4 Facts and Formulas .......................................... 4
1.4.1 Electron Energy Distribution Functions (EEDF) ........ 4
1.4.2 Kinetic Temperature of Electrons ..................... 4
1.4.3 Coefficients for Particle and Energy Transport ....... 5
1.4.4 Generalized Boltzmann Equilibrium .................... 6
1.4.5 Am bipolar Diffusion ................................. 7
1.4.6 Condition of Quasineutrality ......................... 9
1.4.7 Debye Screening Length ............................... 9
1.4.8 Degree of Ionization ................................ 11
1.4.9 Electrical Conductivity ............................. 12
1.4.10 Plasma Frequency .................................... 14
2 Electron Kinetics in Weakly Ionized Plasmas ................ 15
Detlef Loffhagen, Florian Sigeneger, and Rolf Winkler
2.1 Introduction ............................................... 15
2.1.1 The Active Role of Electrons in the Plasma ........... 15
2.1.2 Action of Electric Fields and Collision Processes .... 16
2.2 Kinetic Treatment of the Electrons ......................... 18
2.2.1 Velocity Distribution and Macroscopic Properties ..... 18
2.2.2 Kinetic Equation of the Electrons .................... 19
2.2.3 Treatment of the Kinetic Equation .................... 20
2.2.4 Macroscopic Properties of the Electrons .............. 21
2.3 Kinetics in Time- and Space-Independent Plasmas ............ 23
2.3.1 Basic Equations and Consistent Macroscopic
Balances ............................................. 23
2.3.2 Illustration of Distribution Functions and
Macroscopic Quantities ............................... 25
2.4 Electron Kinetics in Time-Dependent Plasmas ................ 28
2.4.1 Basic Equations for the Distribution Components ...... 28
2.4.2 Balance Equations and Dissipation Frequencies ........ 29
2.4.3 Temporal Relaxation of the Electrons ................. 31
2.5 Electron Kinetics in Space-Dependent Plasmas ............... 32
2.5.1 Basic Equations and Consistent Balances .............. 33
2.5.2 Spatial Relaxation of the Electrons .................. 34
2.6 Electron Kinetics in Time- and Space-Dependent Plasmas ..... 37
2.6.1 Basic Equations and Macroscopic Balances ............. 38
2.6.2 Spatio temporal Relaxation of the Electrons .......... 40
2.7 Concluding Remarks ......................................... 43
2.8 References ................................................. 44
3 Elementary Collision Processes in Plasmas .................. 47
Kurt Becker and Chun C. Lin
3.1 Introduction ............................................... 47
3.2 Electron-impact-induced Collision Processes with Atoms ..... 49
3.2.1 Electron Excitation of Atoms: Overview ............... 49
3.2.2 Electron Excitation Out of Metastable Levels ......... 50
3.2.2.1 Argon: a Case Study .......................... 51
3.2.2.2 Other Rare Gases ............................. 56
3.2.3 Electron-Impact Ionization ........................... 58
3.3 Electron-lmpact-Induced Collision Processes with
Molecules .................................................. 61
3.4 Concluding Remarks ......................................... 67
3.5 References ................................................. 68
4 Elementary Processes of Plasma-Surface Interactions ........ 71
Rainer Hippler
4.1 Introduction ............................................... 71
4.2 Theoretical Considerations ................................. 71
4.2.1 Binary Collision Model ............................... 72
4.2.1.1 Scattering Angle and Energy Transfer ......... 72
4.2.1.2 Stopping Power ............................... 74
4.2.1.3 Sputtering Yield ............................. 77
4.2.1.4 Computer Simulations Based on the Binary
Collision Model .............................. 78
4.2.2 Molecular Dynamics Model ............................. 79
4.2.3 Scattering Potentials ................................ 80
4.2.2 Repulsive Potentials ................................. 80
4.2.3.2 Attractive Potentials ........................ 81
4.3 Scattering of Ions at Surfaces ............................. 84
4.3.1 Implantation of Ions ................................. 84
4.3.2 Backscattering of Ions ............................... 84
4.4 Physical Sputtering ........................................ 86
4.4.1 Projectile Energy Dependence ......................... 86
4.4.2 Energy Distribution of Sputtered Particles ........... 87
4.4.3 Sputtering of Clusters ............................... 89
4.4.4 Potential Sputtering Employing Highly Charged Ions ... 89
4.5 Electron Emission .......................................... 91
4.5.1 Emission of Electrons by Electron Impact ............. 92
4.5.1.1 Reflection of Electrons from Surfaces ........ 93
4.5.1.2 Emission of Secondary Electrons by Electron
Impact ....................................... 94
4.5.2 Emission of Electrons by Ion Impact .................. 94
4.5.3 Emission of Electrons by Cluster Impact .............. 97
4.6 Chemical Effects ........................................... 98
4.6.1 Chemical Sputtering and Plasma Etching ............... 98
4.7 References ................................................ 100
5 Plasma-Surface Interaction .................................. 103
Holger Kersten and Achim von Keudell
5.1 Introduction .............................................. 103
5.2 Elementary Mechanisms in Low-Temperature Plasma
Processing ................................................ 104
5.2.1 Adsorption .......................................... 104
5.2.1.1 Chemisorption versus Physisorption .......... 104
5.2.1.2 Sticking Coefficient and Surface Loss
Probabilities ............................... 105
5.2.1.3 Surface Coverage ............................ 106
5.2.1.4 Surface Diffusion ........................... 108
5.2.1.5 Energy Accommodation ........................ 109
5.2.2 Surface Reactions ................................... 110
5.2.3 Quantification of Surface Reactions ................. 112
5.2.3.1 Estimation of Sticking Coefficients ......... 112
5.2.3.2 Measurement of Sticking Coefficients ........ 112
5.2.4 Ion Bombardment in Plasma Processing ................ 114
5.3 Modeling of Etching and Deposition Processes .............. 116
5.3.1 Particle Balance .................................... 117
5.3.2 Energy Balance ...................................... 118
5.4 Examples .................................................. 120
5.4.1 Example: Deposition of a-Si:H Films ................. 120
5.4.2 Example: Temperature Dependence of Plasma
Etching ............................................. 122
5.4.3 Example: Energy Balance During Thin Film
Deposition .......................................... 124
5.4 References ................................................ 126
6 Fundamentals of Dusty Plasmas ............................. 129
André Melzer and John Goree
6.1 Introduction .............................................. 129
6.2 Particle Charging ......................................... 130
6.2.1 Orbital-Motion Limited Theory ....................... 130
6.2.2 Reduction of the Charge due to High Particle
Density ............................................. 133
6.2.3 Electron Emission ................................... 134
6.2.3.1 Secondary Electron Emission ................. 135
6.2.3.2 Photoelectric Emission ...................... 136
6.2.4 Ion Trapping ........................................ 136
6.2.5 Charge Fluctuations ................................. 137
6.3 Forces on Particles ....................................... 137
6.3.1 Electric Field Force ................................ 137
6.3.2 Gravity ............................................. 138
6.3.3 Ion Drag Force ...................................... 138
6.3.4 Thermophoresis ...................................... 140
6.3.5 Neutral Drag Force .................................. 140
6.3.6 Radiation Pressure Forces ........................... 141
6.3.7 Particle Interaction Potentials ..................... 141
6.3.7.1 Particles in Isotropic Plasmas .............. 141
6.3.7.2 Particles in the Plasma Sheath .............. 142
6.4 Experimental Methods ...................................... 143
6.4.1 Particle Confinement and Levitation ................. 143
6.4.1.1 RF Discharges ............................... 143
6.4.1.2 DC Discharges ............................... 145
6.4.1.3 Discharges with Nanoparticles ............... 146
6.4.2 Charge Measurement Methods .......................... 147
6.4.2.1 The Potential Well .......................... 147
6.4.2.2 Linear Resonances ........................... 147
6.4.2.3 Nonlinear Oscillations ...................... 148
6.4.3 Particle Imaging and Tracking ....................... 149
6.5 Strongly Coupled Systems and Plasma Crystallization ....... 151
6.5.1 Phase Diagram of Charged-Particle Systems ........... 152
6.5.2 Correlation Functions ............................... 153
6.5.3 Phase Transitions ................................... 154
6.5.4 Comparison to Colloids .............................. 154
6.6 Waves in Dusty Plasmas .................................... 157
6.6.1 Waves in Weakly Coupled Plasmas: Dust-Acoustic
Wave(DAW) ........................................... 157
6.6.2 Waves in Strongly Coupled Dusty Plasmas: Dust
Lattice Wave ........................................ 159
6.6.2.1 Dispersion Relations of Longitudinal and
Shear Modes in 2D ........................... 159
6.6.2.2 Measurements of Compressional and Shear
Dust Lattice Waves .......................... 160
6.6.2.3 Mach Cones .................................. 163
6.6.2.4 Transverse Dust Lattice Waves ............... 164
6.6.2.5 Natural Phonons ............................. 164
6.6.3 Finite Clusters and Normal Modes .................... 166
6.6.3.1 2D Clusters ................................. 166
6.6.3.2 3D Clusters: Yukawa (Coulomb) Balls ......... 169
6.7 Concluding Remarks ........................................ 169
6.8 References ................................................ 170
7 Langmuir Probe Diagnostics of Low-Temperature Plasmas .... 175
Sigismund Pfau and Milan Tichý
7.1 Introduction ............................................. 175
7.1.1 Probe Shapes and Probe Characteristics ............. 175
7.1.2 The Working Regimes of the Langmuir Probe .......... 178
7.1.3 Advantages and Disadvantages of Probe
Diagnostics ........................................ 179
7.2 The Langmuir Single-Probe Method ......................... 180
7.2.1 Theoretical Foundations of the Langmuir Probe
Method ............................................. 180
7.2.2 Probe Characteristics - Example of the Spherical
Probe .............................................. 181
7.2.2.1 Probe Current at qvUp ≥ 0 ................... 181
7.2.2.2 Probe Current at qvUp ≤ 0 ................... 182
7.3 General Theories of the Current to a Langmuir Probe ...... 183
7.3.1 Starting System of Equations ....................... 183
7.3.2 The Cold Ion Model by Allen, Boyd, and Reynolds
(Ti/Te = 0) ......................................... 184
7.4 The Druyvesteyn Method for Estimation of the Electron
Energy Distribution Function (EEDF) ...................... 186
7.5 Probe Diagnostics of Anisotropic Plasmas ................. 190
7.6 Probe Diagnostics Under Noncolli si on-Free Conditions ... 192
7.7 Langmuir Probe in a Magnetized Plasma .................... 197
7.8 Space and Time-Resolved Langmuir Probe Method ............ 199
7.8.1 Space-Resolved Langmuir Probe Measurements ......... 199
7.8.2 Time-Resolved Langmuir Probe Measurements .......... 200
7.8.2.1 Time-Resolved Probe Measurements in
Periodically Changing Plasmas at ω < ωpi .... 202
7.8.2.2 Probe Measurements of Time-Averaged Plasma
Parameters at ωpi < ω ≤ ωpe ................. 202
7.8.2.3 Time-Resolved Probe Measurements in
Single-Shot Experiments .................... 204
7.9 Probe Diagnostic of Chemically Active Plasmas ............ 204
7.10 Double-Probe Technique ................................... 206
7.11 References ............................................... 208
8 Emission and absorption spectroscopy ...................... 215
Jürgen Röpcke, Paul B. Davies, Frank Hempel, and
Boris P. Lavrov
8.1 Introduction .............................................. 215
8.2 Instrumental Techniques ................................... 216
8.3 Emission Spectroscopy ..................................... 219
8.3.1 General Considerations .............................. 229
8.3.2 Actinometry ......................................... 220
8.4 Absorption Spectroscopy ................................... 222
8.4.1 General Considerations .............................. 222
8.4.2 Tnfrared Absorption Spectroscopy .................... 224
8.5 Results and Applications: Physical Properties of
Plasmas ................................................... 227
8.5.1 Temperatures and Distribution Functions ............. 228
8.5.1.1 Translational Temperature ................... 228
8.5.1.2 Rotational Temperature ...................... 229
8.5.1.3 Vibrational Temperature ..................... 232
8.5.2 Degree of Dissociation .............................. 233
8.5.3 Electric Field, Electron Temperature, Density and
Distribution Function ............................... 235
8.5.4 Time-Resolved Spectroscopy .......................... 236
8.6 Conclusions ............................................... 237
8.7 References ................................................ 238
9 Mass Spectrometric Diagnostics ............................ 243
Martin Schmidt, Rüdiger Foest, and Ralf Basner
9.1 Introduction .............................................. 243
9.2 Instrumentation ........................................... 245
9.2.1 Ion Source .......................................... 245
9.2.2 Mass Analyzer ....................................... 247
9.2.3 Ion Energy Analyzer ................................. 249
9.2.4 Ion Detector ........................................ 250
9.3 Coupling of the Mass Spectrometer with the Plasma
System .................................................... 250
9.3.1 Mechanical Coupling ................................. 250
9.3.2 Electrical Coupling ................................. 255
9.4 Neutral Gas Mass Spectrometry ............................. 256
9.5 Ion Mass Spectrometry ..................................... 262
9.6 Mass Spectrometry for the Determination of Elementary
Data for Plasma Physics ................................... 266
9.7 Conclusions ............................................... 267
9.6 References ................................................ 267
10 Cross-Correlation Emission Spectroscopy .................. 271
Hans-Erich Wagner, Kirill Vadimovich Kozlov, and
Ronny Brandenburg
10.1 Introduction ............................................. 271
10.2 The Technique of Cross-Correlation Spectroscopy .......... 272
10.3 Investigation of Filamentary and Diffuse Barrier
Discharges ............................................... 275
10.3.1 Discharge Operation ............................... 275
10.3.2 Filamentary Barrier Discharges in Air ............. 277
10.3.3 Systematic Variation of N2/O2 Gas Mixtures ........ 281
10.3.4 Axial and Radial Development of Single
Microdischarges ................................... 282
10.3.5 Determination of Electric Field Strength and
Relative Electron Density in the Microdischarge
Channel in Air .................................... 284
10.3.5.1 Development of E/n and nc along the MD
z-axis ................................... 284
10.3.5.2 Axial and Radial Development of
Electric Field Strength .................. 286
10.3.6 Determination of Effective Lifetime Constants of
States N2+(B2∑u2)u'=0 and N2(C3∏u)u'·0 ................ 289
10.3.7 Transition Between the Filamentary and Diffuse
Barrier Discharges in N2/O2 Gas Mixtures .......... 290
10.3.8 Filamentary and Diffuse Barrier Discharges in
Noble Gas Containing Atmospheres .................. 292
10.3.8.1 Diffuse Barrier Discharges in Gas
Mixtures of Nitrogen with Helium, Neon,
and Argon ................................ 293
10.3.8.2 Diffuse and Filamentary Barrier
Discharges in Ne/O2 Gas Mixtures ......... 295
10.3.8.3 Barrier Discharges in Pure Argon ......... 296
10.4 Investigation of Corona Discharges ....................... 298
10.4.1 Positive Corona Discharges ........................ 298
10.4.2 Negative Corona Discharges ........................ 299
10.5 Summary .................................................. 301
10.6 References ............................................... 302
11 Ellipsometric Analysis of Plasma-Treated Surfaces ........ 307
Wolfgang Fukarek
11.1 Introduction ............................................. 307
11.2 Comparison with Other Techniques ......................... 308
11.3 Experimental Technique ................................... 309
11.3.1 Instrumentation ................................... 309
11.3.2 Data Analysis ..................................... 310
11.4 Examples ................................................. 312
11.4.1 In situ Single Wavelength Ellipsometry Examples ... 312
11.4.1.1 Direct Current (DC) Magnetron Sputter
Deposition of Indium-Tin-Oxide (ITO)
Films .................................... 313
11.4.1.2 Temperature Dependence of a-C:H Film
Growth ................................... 313
11.4.1.3 The Role of Low-Energy Hydrogen Ions in
Plasma-Enhanced Chemical Vapor
Deposition (PECVD) of Hydrocarbon
Films .................................... 315
11.4.2 In situ Spectroscopic Ellipsometry Examples ....... 317
11.4.2.1 Surface Temperature and Oxide Thickness
During Argon Sputter Cleaning ............ 317
11.4.2.2 Analysis of Unstable Plasma Processes .... 319
11.4.2.3 Monitoring of
Ion-Beam-Assisted-Deposition Processes ... 322
11.4.3 Ex situ Spectroscopic Ellipsometry Examples ....... 323
11.4.3.1 In-Plane Anisotropic Turbostratic Boron
Nitride Films ............................ 324
11.4.3.2 Reactive Cathodic Arc Deposition of
Aluminum Oxide Films ..................... 325
11.5 Limitations and Remaining Issues ......................... 326
11.6 References ............................................... 327
12 Characterization of Thin Solid Films ..................... 329
Harm Wulff and Hartmut Steffen
12.1 Introduction ............................................. 329
12.2 X-Ray Methods for Thin Film Analysis ..................... 330
12.2.1 Grazing Incidence X-Ray Diffractometry (GIXD) ..... 330
12.2.2 X-Ray Reflectometry (XR) .......................... 333
12.3 X-Ray Photoelectron Spectroscopy (XPS) ................... 335
12.4 Examples ................................................. 336
12.4.1 Phase Analysis of Plasma-Deposited TiNx Films ..... 336
12.4.2 Characterization of Defect Structures by X-Ray
Investigations .................................... 337
12.4.2.1 Imperfections of the First Type .......... 338
12.4.2.2 Imperfections of the Second Type ......... 338
12.4.3 Calculation of Depth Profiles in
Plasma-Deposited Ti/TiSi Films .................... 341
12.4.4 Structural Studies of Thin ITO Films .............. 343
12.4.5 Investigation of Plasma-Deposited ITO Films ....... 347
12.4.5.1 Influence of Oxygen Flow During Film
Deposition ............................... 348
12.4.5.2 Influence of the Negative Substrate
Voltage .................................. 350
12.4.5.3 Postdeposition Annealing ................. 351
12.4.6 In silu Studies of Diffusion and Crystal Growth
in Plasma-Deposited Thin ITO Films ................ 351
12.4.6.1 Determination of Kinetic Parameters ...... 352
12.4.6.2 Diffusion ................................ 353
12.4.6.3 Crystallization .......................... 355
12.4.7 Formation of Aluminum Oxide Using
a Microwave-Induced Plasma ........................ 356
12.5 Characterization of Ag Clusters .......................... 359
12.6 Conclusions .............................................. 361
12.7 References ............................................... 361
13 Plasma Sources ........................................... 363
Martin Schmidt and Hans Conrads
13.1 Introduction ............................................. 363
13.2 Properties of Nonthermal Plasmas ......................... 365
13.3 Plasma Generation by Electric Fields ..................... 368
13.3.1 Direct Current (dc) Discharges .................... 368
13.3.2 Pulsed Direct Current (dc) Discharges ............. 371
13.3.3 Radiofrequency (rf) Discharges .................... 372
13.3.3.1 Capacitively Coupled Radiofrequency
Discharges ............................... 372
13.3.3.2 Inductively Coupled Radiofrequency
Discharges ............................... 374
13.3.4 Microwave Discharges .............................. 376
13.4 Plasma Generation by Beams ............................... 379
13.5 Conclusions .............................................. 379
13.6 References ............................................... 381
14 Reactive Nonthermal Plasmas .............................. 385
Hans-Erich Wagner
14.1 Introduction ............................................. 385
14.2 Chemical Quasiequilibria ................................. 386
14.2.1 The Concept ....................................... 386
14.2.2 Chemical Quasiequilibria and the Kinetic
Background ........................................ 388
14.2.3 Experimental Verification ......................... 391
14.3 Plasma Chemical Similarity ............................... 394
14.3.1 Similarity Principles in the Chemistry of
Nonthermal Plasmas ................................ 394
14.3.2 Application to the Flow Reactor ................... 396
14.3.3 Comparison with Experimental Results .............. 398
14.4 The Method of Generalized Macroscopic kinetics ........... 401
14.4.1 History and Concept ............................... 401
14.4.2 The Particle Balance Equations .................... 402
14.4.3 Demonstration Examples ............................ 403
14.4.4 Macroscopic Modeling of Experimental Results ...... 405
14.5 Summary .................................................. 407
14.6 References ............................................... 408
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