Handbook of vacuum science and technology

Preface xvii List of Contributors xxi Part 1 Fundamentals of Vacuum Teclinology and Surface Physics I 1.1 Vacuum Nomenclature and Definitions 3 1.1.1 Basic Definition 3 1.1.2 Pressure Regions of Vacuum 3 1.2 Gas Properties 8 1.2.1 Description of Vacuum as a Low-Pressure Gas 8 1.2.2 Characteristics of a Gas—Basic Definitions 8 1.2.3 Gas Laws 9 1.3 Molecular Processes and Kinetic Theory 11 1.3.1 General Description 11 1.3.2 Molecular Motion 12 1.3.3 Kinetic Theory Derivation of the Gas Laws 14 1.3.4 Pressure 15 1.3.5 Molecular Mean Free Path 17 1.3.6 Number of Impacts with the Chamber Wall 19 1.3.7 Time to Form a Monolayer 20 1.3.8 Thermal Transpiration 20 1.3.9 Coefficient of Thermal Conductivity 21 1.3.10 Coefficient of Diffusion 21 1.4 Throughput, Pumping Speed, Evacuation Rate, Outgassing Rate, and Leak Rate 22 1.5 Gas Flow 25 1.5.1 Nature of Gas Flow 25 1.5.2 Turbulent Flow 27 IX 1.5.3 Viscous, Streamline, or Laminar Flow 28 1.5.4 Molecular Flow 29 1.5.5 Flow Relationships 29 1.6 Conductance 32 1.6.1 Conductance 32 1.6.2 Conductances in Parallel 33 1.6.3 Conductances in Series 33 1.7 Flow Calculations 35 1.7.1 Equations for Viscous Flow 35 1.7.2 Equations for Molecular Flow 37 1.7.3 Knudsen's Formulation 37 1.7.4 Clausing Factors 38 1.8 Surface Physics and Its Relation to Vacuum Science 40 1.8.1 Physical Adsorption or "Adsorption" 40 1.8.2 Chemisorption 42 1.8.3 Sticking Coefficient 43 1.8.4 Surface Area 44 1.8.5 Surface Adsorption Isotherms 45 1.8.6 Capillary Action 47 1.8.7 Condensation 48 1.8.8 Desorption Phenomena 49 1.8.9 Thermal Desorption 50 1.8.10 Photoactivation 52 1.8.11 Ultrasonic Desorption 53 1.8.12 Electron- and Ion-Stimulated Desorption 53 1.8.13 Gas Release from Surfaces 54 References 55 Part 2 Creation of Vacuum 57 2.1 Technology of Vacuum Pumps — An Overview 59 2.1.1 Vacuum Pump Function Basics 59 2.1.2 Gas Transport: Throughput 61 2.1.3 Performance Parameters 62 2.1.4 Pumping Speed 64 2.1.5 Pumpdown Time 65 2.1.6 Ultimate Pressure 69 2.1.7 Forevacuum and High-Vacuum Pumping 71 2.1.8 Pump System Relationships 73 2.1.9 Crossover from Rough to High-Vacuum Pumps 78 2.1.10 Pumping System Design 79 References 83 2.2 Diaphragm Pumps 84 2.2.1 Introduction: Basics and Operating Principle 84 2.2.2 State-of-the-Art Design and Manufacturing 87 2.2.3 Performance and Technical Data 91 2.2.4 Modular Concept for Specific Application Setups: Standalone Operation 92 2.2.5 Diaphragm Pumps as Backing and Auxiliary Pumps in Vacuum Systems 93 References 96 2.3 Vacuum Blowers 97 2.3.1 Introduction 97 2.3.2 Equipment Description 97 2.3.3 Blower Operating Principle 100 2.3.4 Blower Pumping Efficiency 101 2.3.5 Blower Pumping Speed Calculations 103 2.3.6 Power Requirements 104 2.3.7 Temperature Considerations 106 2.3.8 Flow and Compression Ratio Control Mechanisms . . . . 108 2.3.9 Liquid-Sealed Blowers 112 2.3.10 Selected System Arrangements 112 2.4 Vacuum Jet Pumps (Diffusion Pumps) 116 2.4.1 Basic Pumping Mechanism 117 2.4.2 Pumping Speed 122 2.4.3 Throughput 127 2.4.4 Tolerable Forepressure 128 2.4.5 Ultimate Pressure 132 2.4.6 Backstreaming 137 2.4.7 Other Performance Aspects 144 References 148 2.5 Cryogenic Pumps 149 2.5.1 Introduction 149 2.5.2 Cryopump Basics 156 2.5.3 Advanced Control Systems 167 2.5.4 Cryopump Process Applications 173 2.5.5 Cryogenic Pumps Specifically for Water Vapor 177 2.5.6 Comparison of Cryopumps to Other Types of Pumps... 179 2.5.7 Future Developments 181 References 181 2.6 Turbomolecular Pumps 183 2.6.1 Turbomolecular Pumps (TMP) 183 2.6.2 Molecular Drag Pumps (MDP) 195 2.6.3 Combination of Pumps (TMP + MDP) 197 2.2.1 Introduction: Basics and Operating Principle 84 2.2.2 State-of-the-Art Design and Manufacturing 87 2.2.3 Performance and Technical Data 91 2.2.4 Modular Concept for Specific Application Setups: Standalone Operation 92 2.2.5 Diaphragm Pumps as Backing and Auxiliary Pumps in Vacuum Systems 93 References 96 2.3 Vacuum Blowers 97 2.3.1 Introduction 97 2.3.2 Equipment Description 97 2.3.3 Blower Operating Principle 100 2.3.4 Blower Pumping Efficiency 101 2.3.5 Blower Pumping Speed Calculations 103 2.3.6 Power Requirements 104 2.3.7 Temperature Considerations 106 2.3.8 Flow and Compression Ratio Control Mechanisms . . . . 108 2.3.9 Liquid-Sealed Blowers 112 2.3.10 Selected System Arrangements 112 2.4 Vacuum Jet Pumps (Diffusion Pumps) 116 2.4.1 Basic Pumping Mechanism 117 2.4.2 Pumping Speed 122 2.4.3 Throughput 127 2.4.4 Tolerable Forepressure 128 2.4.5 Ultimate Pressure 132 2.4.6 Backstreaming 137 2.4.7 Other Performance Aspects 144 References 148 2.5 Cryogenic Pumps 149 2.5.1 Introduction 149 2.5.2 Cryopump Basics 156 2.5.3 Advanced Control Systems 167 2.5.4 Cryopump Process Applications 173 2.5.5 Cryogenic Pumps Specifically for Water Vapor 177 2.5.6 Comparison of Cryopumps to Other Types of Pumps... 179 2.5.7 Future Developments 181 References 181 2.6 Turbomolecular Pumps 183 2.6.1 Turbomolecular Pumps (TMP) 183 2.6.2 Molecular Drag Pumps (MDP) 195 2.6.3 Combination of Pumps (TMP + MDP) 197 Table of Contents 2.6.4 Evaluation of Combinations of Backing Pumps and TMPs, Etc 200 2.6.5 The Use of TMP in Applications: Specific Effects and Demands 208 2.6.6 Avoiding Operational Mistakes 211 References 212 2.7 Pumps for Ultra-High Vacuum Applications 214 2.7.1 System Design for Ultra-High Vacuum 215 2.7.2 The Selection of Pumps for Ultra-High Vacuum Applications 216 2.7.3 Sputter-Ion Pumps 220 2.7.4 Getter Pumps 242 References 252 Part 3 Vacuum Measurements 255 3.1 The Measurement of Low Pressures 257 3.1.1 Overview 258 3.1.2 Direct Reading Gauges 260 3.1.3 Indirect Reading Gauges 265 3.1.4 Calibration of Vacuum Gauges 286 References 288 3.2 Mass Analysis and Partial Pressure Measurements 290 3.2.1 Overview and Applications 290 3.2.2 Inlet Systems 300 3.2.3 Ion Generation and Ion Sources 303 3.2.4 Ion Separation Analyzers 308 3.2.5 Detection of Ions 323 References 326 3.3 Practical Aspects of Vacuum System Mass Spectrometers 335 3.3.1 Historical Insight 335 3.3.2 Expected Gases in a Vacuum System 336 3.3.3 The Ion Generation Process 340 3.3.4 Techniques for Analysis 351 3.3.5 Calibration of Vacuum System Mass Spectrometers 364 3.3.6 Some Applications 370 References 374 3.4 Mass Flow Measurement and Control 376 3.4.1 General Principles of Mass Flow Measurement 376 3.4.2 Overview of Thermal Mass Flow Controller Technology 378 3.4.3 Performance Characteristics 382 3.4.4 Troubleshooting 386 References 387 Part 4 Systems Design and Components 389 4.1 Selection Considerations for Vacuum Valves 391 4.1.1 Introduction 391 4.1.2 Valves for Shutoff 391 4.1.3 Valves forControl 397 4.1.4 Valve Construction 398 4.1.5 Specialty Valves 404 4.1.6 Installation Considerations for Vacuum Valves 407 References 408 4.2 Flange and Component Systems 409 4.2.1 Introduction 409 4.2.2 Selecting a Flange System 410 4.2.3 Conunon Flange Systems 410 4.2.4 Components with Flanges Attached 425 Trademarks 430 References 432 4.3 Magnetic-Fluid-Sealed Rotary Motion Feedthroughs 433 4.3.1 Basic Sealing Principle 433 4.3.2 Application Factors 434 4.3.3 Impact of Feedthrough on Process 436 4.3.4 Impact of Process on Feedthrough 437 4.3.5 Materials Considerations 438 4.3.6 Application Examples 440 4.3.7 Comparison to Other Types of Feedthroughs 442 4.4 Viewports 444 4.4.1 Materials 444 4.4.2 Mounting Systems and Precautions 445 4.5 Construction Materials 446 4.5.1 Properties Defining Material Performance 446 4.5.2 Vacuum Chamber Materials 451 4.5.3 Special-Purpose Materials 455 References 462 4.6 Demountable Seals for Flanges and Valves 463 4.6.1 Sealing Overview: Polymer and Metal Seals 463 4.6.2 The Elastomeric and Nonelastomeric Polymers Used in Vacuum Sealing 464 4.6.3 Metal Seals 474 References 482 4.7 Outgassing of Materials 484 4.7.1 Relationships Among System Pressure, Pumping Speed, and Outgassing 484 5.2.6 Advanced Plasma Etch Reactors 649 5.2.7 New Trends 665 References 667 5.3 Ion Beam Technology 672 5.3.1 Introduction 672 5.3.2 Ion Beam Etching 678 5.3.3 Ion Beam Sputter Deposition 683 5.3.4 lon-Beam-Assisted Deposition 687 5.3.5 Ion Beam Direct Deposition 689 5.3.6 Conclusion 690 References 691 5.4 Pulsed Laser Deposition 694 5.4.1 Introduction 694 5.4.2 Pulsed Laser Deposition System 695 5.4.3 The Ablation Mechanism 698 5.4.4 Advantages and Limitations 700 5.4.5 Materials Survey 705 5.4.6 Future Outlook 708 References 708 5.5 Plasma-Enhanced Chemical Vapor Deposition 711 5.5.1 Introduction 711 5.5.2 Equipment and Other Practical Considerations 717 5.5.3 Process Scaleup 723 5.5.4 Conclusion 727 References 728 5.6 Conmion Analytical Methods for Surface and Thin Film 731 5.6.1 Introduction 731 5.6.2 The Electron Spectroscopies 732 5.6.3 Methods Based on Ion Bombardment 745 5.6.4 UHV Generation and System Considerations for Surface Analysis 755 References 757 Part 6 Large-Scale Vacuum-Based Processes 759 6.1 RoU-to-RoU Vacuum Coating 761 6.1.1 Overview of RoU-to-Roll Vacuum Coating 761 6.1.2 Typical Products 764 6.1.3 Materials and Deposition Processes Conmionly Used in RoU-to-RoU Coating 765 6.1.4 Vacuum Systems for Roll-to-RoU Coating Applications. 775 6.1.5 Substrates (Webs) 779 6.1.6 Process Control 783 6.1.7 Specific Problems Exhibited by Coatings 784 References 787 6.2 The Development of Ultra-High-Vacuum Technology for Particle Accelerators and Magnetic Fusion Devices 789 6.2.1 Introduction 789 6.2.2 Storage Rings and the Need for UHV 790 6.2.3 UHV for Early Storage Rings 793 6.2.4 Storage Ring Vacuum Vessel and Pumping System Developments 796 6.2.5 Cold-Bore Machines 798 6.2.6 Superconducting RF Accelerators 800 6.2.7 The Next-Generation Big Accelerator? 801 6.2.8 The Magnetic Fusion Road Map 801 6.2.9 The Early History of Magnetic Fusion 803 6.2.10 Model C: The First UHV Fusion Device 804 6.2.11 The Russian Revolution in Fusion: Tokamaks 805 6.2.12 Plasma Impurities and Vacuum Technology 806 6.2.13 Toward the Breakeven Demonstrations 808 6.2.14 The Next Step in Fusion 810 Acknowledgments 810 References 812