Tetrahedrally Bonded Amorphous Carbon Films I (eBook)

After some years in the semiconductor industry, Prof. Schultrich (born 1942) worked for more than ten years at the Technical University of Dresden, Dresden in the field of theoretical physics and its application to the micromechanics of solids. He then joined the Central Institute of Solid State Physics and Materials Research of the Academy of Sciences, Dresden working for ten years on fundamental problems of preparation and properties of refractory carbides and nitrides and corresponding composites (hardmetals and cermets) and their application in the tool industry. From 1990 up to his retirement, he headed the PVD (physical vapour deposition) thin film department in the Fraunhofer Institute for Materials and Beam Technology, Dresden. His activities were concentrated on arc and laser-assisted ablation and deposition technologies for industrial applications with the main focus on carbon-based materials. Here his group achieved the breakthrough for the industrial maturity of ta-C (tetrahedral amorphous carbon) films and their preparation.

Preface 7
Contents 11
Acronyms 21
Symbols 24
Subscripts 29
Carbon Materials and Coatings 31
1 Carbon 32
1.1 Carbon Bonds 33
1.2 Diamond 37
1.3 Graphite 40
1.4 The Diamond-Graphite Transition 42
1.5 Engineering Carbon Materials 44
1.6 Melting of Carbon Materials 52
1.7 Vaporization of Carbon Materials 58
1.8 Rules and Theses 64
References 66
2 Diamond Films 70
2.1 Growth 70
2.1.1 Hydrogen 71
2.1.2 Substrate Temperature 72
2.1.3 Carbon/Hydrogen Ratio 72
2.2 Deposition Methods 73
2.2.1 Hot Filament Deposition 76
2.2.2 Plasma Enhanced CVD 77
2.2.3 Further Methods 78
2.3 Nucleation 78
2.3.1 Scratching Nucleation 79
2.3.2 Nucleation Layers 80
2.3.3 Bias Enhanced Nucleation (BEN) 81
2.4 Film Structure and Surface Morphology 83
2.4.1 Textured Growth 83
2.4.2 Highly Oriented Diamond 86
2.4.3 Single Crystalline Films 87
2.4.4 Nanocrystalline Films 89
2.5 Properties and Applications 89
2.5.1 Mechanical Properties 89
2.5.2 Tools 92
2.5.3 Dynamic Systems 93
2.5.4 Electrochemistry 93
2.5.5 Thermal Conductivity 94
2.5.6 Optical Windows 96
2.5.7 Electronics 97
2.6 Rules and Theses 98
References 101
3 Nanodiamond Films 113
3.1 Preparation 113
3.1.1 Ultradense Nucleation 113
3.1.2 Renucleation by Reduced Hydrogen Etch 115
3.1.3 Bias-Enhanced Growth 116
3.1.4 Argon Process 119
3.2 Properties and Applications 121
3.2.1 Mechanical Properties 121
3.2.2 Thermal Conductivity 121
3.2.3 Electrical Conductivity 123
3.2.4 Transparency 123
3.2.5 Applications 124
3.3 Low Temperature Deposition 124
3.3.1 Additional Reactive Elements 125
3.3.2 Increased Hydrocarbon Supply 126
3.3.3 Intensified Precursor Excitation 126
3.3.4 Argon Plasma 126
3.4 Rules and Theses 127
References 128
4 Amorphous Carbon Films 133
4.1 Classification 133
4.2 Hydrogen Content 135
4.3 Rules and Theses 137
References 138
5 Hydrogenated Amorphous Carbon Films (a-C:H) 139
5.1 Overview 139
5.1.1 ta-C:H Films 139
5.1.2 Plasma Enhanced CVD (PECVD) 140
5.1.3 Structural Classification 140
5.2 Preparation 141
5.2.1 Deposition Conditions 141
5.2.2 Precursor Effects 143
5.2.3 Frequency Effects 143
5.2.4 rf PECVD 145
5.2.5 ECR PECVD 149
5.2.6 mf PECVD 150
5.2.7 dc PECVD 150
5.2.8 Arc Jet 151
5.2.9 Atmospheric Plasma CVD 151
5.2.10 Electrochemical Deposition 152
5.3 Growth 154
5.3.1 Surface Effects of Radicals and Ions 155
5.3.2 Balance of Particle Fluxes 155
5.3.3 Surface Roughness 156
5.4 Hydrogen Content 157
5.4.1 Unbound Hydrogen 157
5.4.2 Hydrogen Incorporation 157
5.4.3 Hydrogen Reduction 158
5.5 Structure 159
5.5.1 Bonding State 160
5.5.2 Structure Types 161
5.5.3 Density 162
5.6 Properties 165
5.6.1 Mechanical Properties 167
5.6.2 Thermal Properties 172
5.6.3 Optical Properties 174
5.6.4 Electrical Properties 179
5.6.5 Structural Stability 180
5.7 Applications 182
5.7.1 Components 183
5.7.2 Tools 184
5.7.3 Transparent Protective Coatings 184
5.7.4 Permeation Barriers 185
5.7.5 Potential Applications 186
5.8 Nonmetal Containing a-C:H:X Films 186
5.8.1 a-C:H:N 187
5.8.2 a-C:H:Si, a-C:H:Si:O 188
5.8.3 a-C:H:F 189
5.8.4 Mechanical Properties 189
5.8.5 Friction 189
5.8.6 Wettability 191
5.8.7 Low ? Dielectrics 192
5.9 Metal Containing a-C:H:Me Films 194
5.9.1 Preparation 194
5.9.2 Structure 196
5.9.3 Stress Reduction 200
5.9.4 Hardness and Stiffness 201
5.9.5 Friction and Wear 204
5.9.6 Resistivity 205
5.10 Rules and Theses 206
References 211
Structural Development of ta-C Films 221
6 Structure of Amorphous Carbon 222
6.1 Structural Characterization of Amorphous Carbon 222
6.1.1 sp3 Fraction s 224
6.1.2 Density 225
6.1.3 Radial Density Function g(r) 227
6.1.3.1 Distances 229
6.1.3.2 Angles 229
6.1.3.3 Neighbors 230
6.1.3.4 Bond Order 231
6.1.4 Additional Characteristics from Simulated Structures 231
6.1.5 Raman Spectrum 233
6.1.6 Surface Acoustic Waves 239
6.2 Modelling of ta-C Structures 241
6.2.1 Simulation Procedure 241
6.2.2 Simulation Methods 244
6.2.3 Interatomic Potentials 246
6.2.4 Reverse Monte Carlo Technique (RMC) 252
6.3 Structure of Amorphous Silicon 253
6.3.1 Hydrogen-Free a-Si 253
6.3.2 Liquid Silicon 256
6.4 Structure of Liquid Carbon 258
6.5 Structure of ta-C with Highest sp3 Content 260
6.5.1 sp3 Content and Density 262
6.5.2 Radial Density Function 263
6.5.3 Additional Characteristics 267
6.5.3.1 Partial Distributions 267
6.5.3.2 Ring Statistics 268
6.5.3.3 Distribution of the sp2 Bonded Atoms 269
6.5.4 Comparison with a-Si 269
6.6 Structure of ta-C with Reduced sp3 Content 270
6.6.1 Density of Amorphous Carbon 271
6.6.2 Radial Density Function 274
6.6.3 Additional Characteristics 278
6.6.3.1 Ring Statistics 278
6.6.3.2 Distribution of the sp2 Bonded Atoms 279
6.6.4 Possible Nanodiamond Inclusions 280
6.7 Top Layer 281
6.8 Ultrathin Films 284
6.9 Rules and Theses 286
6.9.1 Structural Characterization of Amorphous Carbon 286
6.9.2 Modelling of ta-C Structures 288
6.9.3 Structure of Amorphous Silicon 288
6.9.4 Structure of Liquid Carbon 289
6.9.5 Structure of ta-C with Highest sp3 Content 289
6.9.6 Structure of ta-C with Reduced sp3 Content 290
6.9.7 Top Layer 290
6.9.8 Ultrathin Films 290
References 291
7 Influence of Deposition Conditions 300
7.1 Ion Beam Deposition 301
7.2 Energy of the Incident Carbon Ions 303
7.2.1 lessthan 20 eV 304
7.2.2 20–600 eV 304
7.2.3 600–10 keV 305
7.2.4 greaterthan 10 keV 305
7.3 Angle of Incidence 307
7.4 Substrate Temperature and Deposition Rate 309
7.5 Layered Carbon Films 317
7.5.1 Designed Multilayer 317
7.5.2 Unintentional Layering 319
7.6 Rules and Theses 320
References 323
8 Growth of ta-C Films 326
8.1 Subplantation 327
8.1.1 Subplantation Growth Mode 327
8.1.2 Parameter Range for Subplantation Growth 331
8.1.3 Penetration Threshold 335
8.1.4 Process Stages and Time Scales 336
8.1.4.1 Duration of a Collision Cascade 336
8.1.4.2 Duration of the Thermal Spike 338
8.1.4.3 Interval Between Subsequent Impacts 340
8.2 Collision Cascade 341
8.2.1 Binary Collision Approximation (BCA) 341
8.2.2 Ion Track and Penetration Depth 344
8.2.3 Collision Cascade 347
8.2.4 Energy Dissipation 351
8.3 Impact-Induced Film Growth 354
8.3.1 Thermodynamical Estimations 354
8.3.2 Atomic Simulation 356
8.3.3 Growth Models 363
8.3.3.1 Compressive Stress Model 363
8.3.3.2 Thermal Spike Relaxation 365
8.3.3.3 Subplantation Model 366
8.3.3.4 Peening Model 368
8.3.3.5 Thermal Spike Model 369
8.3.3.6 Thermoelastic Spike Model 370
8.3.4 Transient HP/HT Model 371
8.3.5 Phenomenological Description 373
8.4 Thermally Modified Film Growth 375
8.4.1 Thermally Activated Relaxation 376
8.4.1.1 Stress Induced Relaxation 379
8.5 Rules and Theses 381
Explanations 384
E1 Stopping Power S with Power Law (for (8.5), (8.32)) 384
E2 Binary Collision Approximation and TRIM Program (for Sect. 8.2) 385
E3 Film Growth by Subplantation (for (8.28)) 387
E4 Kinchin-Pease Model (for Sect. 8.2) 389
E5 Thermal Spike Model (for Sect. 8.3) 390
E6 Surface Force on Point Defects (for Sect. 8.4) 392
References 393
Vacuum Arc Deposition of Carbon Films 398
9 Vacuum Arc Discharges with Carbon Cathodes 399
9.1 Current-Voltage Characteristic 401
9.2 Cathode Spots 406
9.2.1 Spot Size 406
9.2.2 Energy Fluxes 407
9.2.3 Spot Structure 410
9.2.4 Spot Dynamic 416
9.3 Arc Plasma 422
9.3.1 Plasma Formation 423
9.3.2 Plasma State 424
9.3.3 Ion Beam Acceleration 425
9.3.4 Free Expansion 427
9.3.5 Mass Flow 428
9.3.6 Ion Energy 432
9.4 Macroparticles 438
9.4.1 Ejection of Macroparticles 439
9.4.2 Flight of the Macroparticles 444
9.4.3 Attachment of the Particles at the Substrate Surface 447
9.4.4 Incorporation of the Macroparticles With Resulting Film Defects 452
9.4.5 Elimination of Macroparticles from the Growing Film 454
9.5 Peculiarities of Graphite Ablation by Vacuum Arc Discharges 456
9.6 Carbon Film Deposition with Vacuum Arc Discharges 460
9.6.1 Unbiased Substrates 460
9.6.2 Biased Substrates 461
9.6.3 Substrate Temperature 465
9.7 Rules and Theses 467
References 471
10 Methods of Vacuum Arc Deposition of ta-C Films 479
10.1 Magnetically Driven DC Vacuum Arcs 479
10.2 Pulsed High Current Vacuum Arcs 490
10.2.1 Expanding Spot System 490
10.2.2 Pecularities of Kiloampere Arc Currents 493
10.2.3 Influence of Fast Changing Arc Conditions 496
10.3 Arc Ignition with High Repetition Rates 498
10.3.1 Contact Separation 499
10.3.2 Ignition by Insulator Breakdown 499
10.3.3 Ignition by Laser Pulses 503
10.3.4 Ignition by High Power Sputtering 507
10.3.5 Superpulsed DC Arc 509
10.4 Rules and Theses 512
References 514
11 Vacuum Arc with Particle Filtering 518
11.1 Concept of Magnetic Filtering 518
11.2 Macroparticle Filter Efficiency 523
11.3 Plasma Filter Transparency 530
11.4 Filter Systems for Minimum Macroparticle Transparency 535
11.5 Filter Systems for Large Area Deposition 539
11.6 Compact Arc Filters 544
11.7 Rules and Theses 547
References 548
12 Special Arc Modes with Reduced Macroparticle Emission 552
12.1 Distributed Arc 552
12.2 Stationary Arc 558
12.3 Shunting Arc 560
12.4 Rules and Theses 565
References 566
13 Vacuum Arc Equipment for Mass Production of ta-C Coatings 569
13.1 Demands on Industrial Equipment for Coating of Tools and Components 569
13.2 Technological Cycle 571
13.2.1 Pre-delivery Check 571
13.2.2 Wet Cleaning 572
13.2.3 Loading 572
13.2.4 Evacuation 573
13.2.5 Plasma Cleaning 573
13.2.6 Interface Preparation 576
13.2.7 Deposition 576
13.2.8 Cooling and Venting 579
13.2.9 Final Inspection 579
13.2.10 Aftertreatment 580
13.3 Industrial Vacuum Arc Devices for ta-C Deposition 581
13.3.1 General Aspects 582
13.3.2 Medium Sized Cathodes 584
13.3.3 Large Cathodes 591
13.3.4 Deposition Rate for Rotating Carriers 596
13.4 Rules and Theses 598
Explanations 601
E1 Deposition Rate on the Central Axis (for 13.10, 13.13) 601
E2 Deposition Rate with Rotating Carriers (for 13.16, 13.17) 603
References 605
Deposition of ta-C Films by Pulsed Laser and by Sputtering 606
14 Carbon Ablation with ns Lasers 607
14.1 PLD Arrangement 607
14.2 Target Heating 611
14.2.1 Energy Input 611
14.2.2 Surface Temperature 616
14.3 Target Ablation 618
14.4 Plasma Formation 620
14.5 Plasma Beam 627
14.5.1 Plasma Propagation 627
14.5.2 Angular Distribution 630
14.5.3 Plasma Composition 632
14.6 Plasma Energies 636
14.6.1 KrF Laser 638
14.6.2 ArF Laser 644
14.6.3 Nd-YAG Laser 644
14.6.4 VIS-Laser 645
14.7 Rules and Theses 646
References 650
15 Carbon Film Deposition with ns Lasers 654
15.1 Influence of Laser Intensity 655
15.1.1 ArF Laser 656
15.1.2 KrF Laser 658
15.1.3 Nd-YAG Lasers 660
15.2 Influence of Laser Wavelength 663
15.3 Macroparticles 665
15.4 Influence of the Target Material 672
15.5 Rules and Theses 675
References 677
16 Related Deposition Methods 681
16.1 Comparison of PLD and Vacuum Arc Deposition of ta-C Films 681
16.1.1 Control of Target Erosion 683
16.1.2 Carbon Plasma 683
16.1.3 Deposition Efficiency 684
16.2 ns-PLD with Additional Activation 686
16.3 Peculiarities of Carbon Deposition with ps and fs Lasers 689
16.4 Rules and Theses 694
16.4.1 Comparison of ns-PLD and Vacuum Arc Deposition of ta-C Films 694
16.4.2 ns-PLD with Additional Activation 694
16.4.3 ps and fs Lasers 695
References 696
17 Activated Sputter Deposition of ta-C Films 699
17.1 Sputtering of Carbon 699
17.1.1 Yield of Carbon Sputtering 700
17.1.2 Energy of the Sputtered Carbon Particles 704
17.2 Dual Ion Beam Sputtering 705
17.3 Magnetron Sputtering 709
17.3.1 Plasma Sputtering 709
17.3.2 Balanced Magnetron 710
17.3.3 Collisional Energy Loss 711
17.3.4 Particle Fluxes 713
17.3.5 Ion Beam Assisted Magnetron Sputtering 715
17.3.6 Plasma Enhanced Magnetron Sputtering 716
17.3.7 Filtered Carbon Sputtering 725
17.3.8 ta-C Deposition in Industrial Magnetron Coaters 726
17.4 High Power Impulse Magnetron Sputtering 730
17.5 Rules and Theses 735
References 737
Appendix A : Specific Methods for ta-C Characterization 740
A.1 Ultrasonic Surface Waves 740
Dispersion Curve 740
Laser Acoustics 744
References 746
A.2 Raman Spectroscopy 746
Basics 746
Raman Spectrum of Carbon Materials 748
Description of the Raman Peaks 750
Raman Spectrum and Carbon Structure 751
Influence of Excitation Wavelength 754
Influence of Hydrogen on the Raman spectrum 755
References 757
Appendix B: Values and Relations 759
B.1 Physical Constants 759
B.2 Units 759
B.3 Carbon 759
B.4 Carbon Materials 760
B.5 Hydrogen-free Amorphous Carbon Films 761
B.6 Hydrogenated Amorphous Carbon Films 764
Index 766