A USERS GUIDE TO VACUUM TECHNOLOGY Choose and understand the vacuum technology that fits your project’s needs with this indispensable guide
Vacuum technology is used to provide process environments for other kinds of engineering technology, making it an unsung cornerstone of hundreds of projects incorporating analysis, research and development, manufacturing, and more. Since it is very often a secondary technology, users primarily interested in processes incorporating it will frequently only encounter vacuum technology when purchasing or troubleshooting. There is an urgent need for a guide to vacuum technology made with these users in mind.
For decades, A User’s Guide to Vacuum Technology has met this need, with a user-focused introduction to vacuum technology as it is incorporated into semiconductor, optics, solar sell, and other engineering processes. With an emphasis on otherwise neglected subjects and on accessibility to the secondary user of vacuum technology, it balances treatment of older systems that are still in use with a survey of the latest cutting-edge technologies. The result promises to continue as the essential guide to vacuum systems.
Readers of the fourth edition of A User’s Guide to Vacuum Technology will also find:
Expanded treatment of gauges, pumps, materials, systems, and best??operating practices Detailed discussion of cutting-edge topics like ultraclean vacuum and contamination control An authorial team with decades of combined research and engineering experience
A User’s Guide to Vacuum Technology is essential for those entering emerging STEM programs, engineering professionals and graduate students working with a huge range of engineering technologies.
Preface xvii Symbols xix Part I Its Basis 1 1 Vacuum Technology 3 1.1 Units of Measurement 8 References 9 2 Gas Properties 11 2.1 Kinetic Picture of a Gas 11 2.1.1 Velocity Distribution 12 2.1.2 Energy Distribution 13 2.1.3 Mean Free Path 14 2.1.4 Particle Flux 15 2.1.5 Monolayer Formation Time 15 2.1.6 Pressure 16 2.2 Gas Laws 16 2.2.1 Boyle’s Law 17 2.2.2 Amontons’ Law 17 2.2.3 Charles’ Law 18 2.2.4 Dalton’s Law 18 2.2.5 Avogadro’s Law 18 2.2.6 Graham’s Law 19 2.3 Elementary Gas Transport Phenomena 19 2.3.1 Viscosity 19 2.3.2 Thermal Conductivity 22 2.3.3 Diffusion 23 2.3.4 Thermal Transpiration 24 References 25 3 Gas Flow 27 3.1 Flow Regimes 27 3.2 Flow Concepts 29 3.3 Continuum Flow 31 3.3.1 Orifice 32 3.3.2 Long Round Tube 34 3.3.3 Short Round Tube 36 3.4 Molecular Flow 37 3.4.1 Orifice 38 3.4.2 Long Round Tube 39 3.4.3 Short Round Tube 39 3.4.4 Irregular Structures 41 3.4.4.1 Analytical Solutions 42 3.4.4.2 Statistical Solutions 43 3.4.5 Components in Parallel and Series 43 3.5 Models Spanning Molecular and Viscous Flow 53 References 55 4 Gas Release from Solids 59 4.1 Vaporization 59 4.2 Diffusion 60 4.2.1 Reduction of Outdiffusion by Vacuum Baking 62 4.3 Thermal Desorption 63 4.3.1 Zero Order 63 4.3.2 First Order 64 4.3.3 Second Order 65 4.3.4 Desorption from Real Surfaces 67 4.3.5 Outgassing Measurements 67 4.3.6 Outgassing Models 69 4.3.7 Reduction by Baking 69 4.4 Stimulated Desorption 71 4.4.1 Electron-Stimulated Desorption 71 4.4.2 Ion-Stimulated Desorption 71 4.4.3 Stimulated Chemical Reactions 72 4.4.4 Photo Desorption 72 4.5 Permeation 73 4.5.1 Atomic and Molecular Permeation 73 4.5.2 Dissociative Permeation 74 4.5.3 Permeation and Outgassing Units 75 4.6 Pressure Limitations During Pumping 76 References 78 Part II Measurement 81 5 Pressure Gauges 83 5.1 Direct Reading Gauges 83 5.1.1 Diaphragm and Bourdon Gauges 84 5.1.2 Capacitance Manometer 85 5.2 Indirect Reading Gauges 88 5.2.1 Thermal Conductivity Gauges 88 5.2.1.1 Pirani Gauge 90 5.2.1.2 Thermocouple Gauge 91 5.2.1.3 Stability and Calibration 92 5.2.2 Spinning Rotor Gauge 93 5.2.3 Ionization Gauges 95 5.2.3.1 Hot Cathode Gauges 95 5.2.3.2 Hot Cathode Gauge Errors 100 5.2.3.3 Cold Cathode Gauge 103 5.2.3.4 Gauge Calibration 105 References 105 6 Flow Meters 109 6.1 Molar Flow, Mass Flow, and Throughput 109 6.2 Rotameters and Chokes 111 6.3 Differential Pressure Devices 112 6.4 Thermal Mass Flow Technique 114 6.4.1 Mass Flow Meter 114 6.4.2 Mass Flow Controller 117 6.4.3 Mass Flow Meter Calibration 119 References 119 7 Pumping Speed 121 7.1 Definition 121 7.2 Mechanical Pump Speed Measurements 122 7.3 High Vacuum Pump Speed Measurements 123 7.3.1 Methods 123 7.3.2 Gas and Pump Dependence 124 7.3.3 Approximate Speed Measurements 125 7.3.4 Errors 125 References 127 8 Residual Gas Analyzers 129 8.1 Instrument Description 129 8.1.1 Ion Sources 131 8.1.1.1 Open Ion Sources 131 8.1.1.2 Closed Ion Sources 133 8.1.2 Mass Filters 134 8.1.2.1 Magnetic Sector 134 8.1.2.2 RF Quadrupole 135 8.1.2.3 Resolving Power 138 8.1.3 Detectors 138 8.1.3.1 Discrete Dynode Electron Multiplier 139 8.1.3.2 Continuous Dynode Electron Multiplier 140 8.2 Installation and Operation 142 8.2.1 Operation at High Vacuum 142 8.2.1.1 Sensor Mounting 142 8.2.1.2 Stability 143 8.2.2 Operation at Medium and Low Vacuum 145 8.2.2.1 Differentially Pumped Analysis 145 8.2.2.2 Miniature Quadrupoles 148 8.3 Calibration 148 8.4 Choosing an Instrument 149 References 150 9 Interpretation of RGA Data 153 9.1 Cracking Patterns 153 9.1.1 Dissociative Ionization 153 9.1.2 Isotopes 154 9.1.3 Multiple Ionization 154 9.1.4 Combined Effects 154 9.1.5 Ion–Molecule Reactions 157 9.2 Qualitative Analysis 158 9.3 Quantitative Analysis 163 9.3.1 Isolated Spectra 164 9.3.2 Overlapping Spectra 165 References 169 Part III Production 171 10 Mechanical Pumps 173 10.1 Rotary Vane 173 10.2 Lobe 177 10.3 Claw 180 10.4 Multistage Lobe 182 10.5 Scroll 184 10.6 Screw 185 10.7 Diaphragm 185 10.8 Reciprocating Piston 187 10.9 Mechanical Pump Operation 189 References 189 11 Turbomolecular Pumps 191 11.1 Pumping Mechanism 191 11.2 Speed–Compression Relations 192 11.2.1 Maximum Compression 193 11.2.2 Maximum Speed 195 11.2.3 General Relation 197 11.3 Ultimate Pressure 198 11.4 Turbomolecular Pump Designs 199 11.5 Turbo-Drag Pumps 201 References 203 12 Diffusion Pumps 205 12.1 Pumping Mechanism 205 12.2 Speed–Throughput Characteristics 207 12.3 Boiler Heating Effects 211 12.4 Backstreaming, Baffles, and Traps 212 References 215 13 Getter and Ion Pumps 217 13.1 Getter Pumps 217 13.1.1 Titanium Sublimation 218 13.1.2 Non-evaporable Getters 223 13.2 Ion Pumps 224 References 229 14 Cryogenic Pumps 233 14.1 Pumping Mechanisms 234 14.2 Speed, Pressure, and Saturation 237 14.3 Cooling Methods 241 14.4 Cryopump Characteristics 245 14.4.1 Sorption Pumps 246 14.4.2 Gas Refrigerator Pumps 249 14.4.3 Liquid Cryogen Pumps 253 References 253 Part IV Materials 257 15 Materials in Vacuum 259 15.1 Metals 260 15.1.1 Vaporization 260 15.1.2 Permeability 260 15.1.3 Outgassing 261 15.1.3.1 Dissolved Gas 262 15.1.3.2 Surface and Near-Surface Gas 264 15.1.4 Structural Metals 269 15.2 Glasses and Ceramics 272 15.3 Polymers 277 References 281 16 Joints Seals and Valves 285 16.1 Permanent Joints 285 16.1.1 Welding 286 16.1.2 Soldering and Brazing 290 16.1.3 Joining Glasses and Ceramics 291 16.2 Demountable Joints 293 16.2.1 Elastomer Seals 294 16.2.2 Metal Gaskets 300 16.3 Valves and Motion Feedthroughs 302 16.3.1 Small Valves 302 16.3.2 Large Valves 304 16.3.3 Special-Purpose Valves 307 16.3.4 Motion Feedthroughs 308 References 313 17 Pump Fluids and Lubricants 315 17.1 Pump Fluids 315 17.1.1 Fluid Properties 315 17.1.1.1 Vapor Pressure 316 17.1.1.2 Other Characteristics 319 17.1.2 Fluid Types 319 17.1.2.1 Mineral Oils 320 17.1.2.2 Esters 321 17.1.2.3 Silicones 321 17.1.2.4 Ethers 322 17.1.2.5 Fluorochemicals 322 17.1.3 Selecting Fluids 323 17.1.3.1 Rotary, Vane, and Lobe Pump Fluids 323 17.1.3.2 Turbo Pump Fluids 325 17.1.3.3 Diffusion Pump Fluids 325 17.1.4 Reclamation 328 17.2 Lubricants 328 17.2.1 Lubricant Properties 329 17.2.1.1 Absolute Viscosity 330 17.2.1.2 Kinematic Viscosity 331 17.2.1.3 Viscosity Index 332 17.2.2 Selecting Lubricants 333 17.2.2.1 Liquid 333 17.2.2.2 Grease 334 17.2.2.3 Solid Film 336 References 338 Part V Systems 341 18 Rough Vacuum Pumping 343 18.1 Exhaust Rate 344 18.1.1 Pump Size 344 18.1.2 Aerosol Formation 346 18.2 Crossover 350 18.2.1 Minimum Crossover Pressure 351 18.2.2 Maximum Crossover Pressure 354 18.2.2.1 Diffusion 354 18.2.2.2 Turbo 357 18.2.2.3 Cryo 357 18.2.2.4 Sputter-Ion 360 References 362 19 High Vacuum Systems 365 19.1 Diffusion-Pumped Systems 365 19.1.1 Operating Modes 368 19.1.2 Operating Issues 369 19.2 Turbo-Pumped Systems 371 19.2.1 Operating Modes 374 19.2.2 Operating Issues 375 19.3 Sputter-Ion-Pumped Systems 376 19.3.1 Operating Modes 377 19.3.2 Operating Issues 379 19.4 Cryo-Pumped Systems 379 19.4.1 Operating Modes 380 19.4.2 Regeneration 380 19.4.3 Operating Issues 382 19.5 High Vacuum Chambers 383 19.5.1 Managing Water Vapor 384 References 386 20 Ultraclean Vacuum Systems 387 20.1 Ultraclean Pumps 389 20.1.1 Dry Roughing Pumps 390 20.1.2 Turbopumps 390 20.1.3 Cryopumps 390 20.1.4 Sputter-Ion, TSP, and NEG Pumps 391 20.2 Ultraclean Chamber Materials and Components 392 20.3 Ultraclean System Pumping and Pressure Measurement 394 References 398 21 Controlling Contamination in Vacuum Systems 401 21.1 Defining Contamination in a Vacuum Environment 401 21.1.1 Establishing Control of Vacuum Contamination 401 21.1.2 Types of Vacuum Contamination 402 21.1.2.1 Particle Contamination 403 21.1.2.2 Gas Contamination 409 21.1.2.3 Film Contamination 410 21.2 Pump Contamination 411 21.2.1 Low/Rough and Medium Vacuum Pump Contamination 411 21.2.1.1 Fluid-Sealed Mechanical Pumps 412 21.2.1.2 Dry Mechanical Pumps 413 21.2.2 High and UHV Vacuum Pump Contamination 415 21.2.2.1 Diffusion Pumps 416 21.2.2.2 Turbo- and Turbo-Drag Pumps 417 21.2.2.3 Cryopumps 418 21.2.2.4 Sputter-Ion and Titanium-Sublimination Pumps 419 21.3 Evacuation Contamination 420 21.3.1 Particle Sources 420 21.3.2 Remediation Methods 421 21.4 Venting Contamination 422 21.5 Internal Components, Mechanisms, and Bearings 423 21.6 Machining Contamination 426 21.6.1 Cutting, Milling, and Turning 426 21.6.2 Grinding and Polishing 427 21.6.3 Welding 428 21.7 Process-Related Sources 429 21.7.1 Deposition Sources 429 21.7.2 Leak Detection 430 21.8 Lubrication Contamination 432 21.8.1 Liquid Lubricants 432 21.8.2 Solid Lubricants 433 21.8.3 Lamellar, Polymer, and Suspension Lubricants 434 21.9 Vacuum System and Component Cleaning 434 21.9.1 Designing a Cleaning Process 435 21.10 Review of Clean Room Environments for Vacuum Systems 436 21.10.1 The Cleanroom Environment 438 21.10.2 Using Vacuum Systems in a Cleanroom Environment 438 References 442 22 High Flow Systems 445 22.1 Mechanically Pumped Systems 447 22.2 Throttled High Vacuum Systems 449 22.2.1 Chamber Designs 449 22.2.2 Turbo Pumped 451 22.2.3 Cryo Pumped 455 References 459 23 Multichambered Systems 461 23.1 Flexible Substrates 462 23.2 Rigid Substrates 465 23.2.1 Inline Systems 465 23.2.2 Cluster Systems 469 23.3 Analytical Instruments 472 References 472 24 Leak Detection 475 24.1 Mass Spectrometer Leak Detectors 476 24.1.1 Forward Flow 476 24.1.2 Counter flow 477 24.2 Performance 478 24.2.1 Sensitivity 478 24.2.2 Response Time 480 24.2.3 Testing Pressurized Chambers 481 24.2.4 Calibration 482 24.3 Leak Hunting Techniques 483 24.4 Leak Detecting with Hydrogen Tracer Gas 486 References 487 Part VI Appendices 489 Appendix A Units and Constants 491 Appendix B Gas Properties 495 Appendix C Material Properties 509 Appendix D Isotopes 519 Appendix E Cracking Patterns 525 Appendix F Pump Fluid Properties 535 Index 543
John F. O'Hanlon, PhD, Emeritus Professor of Electrical and Computer Engineering at the University of Arizona, Tucson, USA and retired IBM Research Staff Member. He is a Senior Member of the IEEE, a Fellow of the AVS and has published widely on vacuum technology and related subjects. Timothy A. Gessert, PhD, is Principal Scientist and Managing Member of Gessert Consulting, LLC, USA, former Principal Scientist at the National Renewable Energy Laboratory, USA, and Fellow and Past President of the AVS. He has published extensively on vacuum technology and related subjects.
