Fundamentals of Vacuum Technology 00.200.02 Kat.-Nr. 199 90 Preface Oerlikon Leybold Vacuum, a member of the globally active industrial Oerlikon Group of companies has developed into the world market leader in the area of vacuum technology. In this leading position, we recognize that our customers around the world count on Oerlikon Leybold Vacuum to deliver technical superiority and maximum value for all our products and services. Today, Oerlikon Leybold Vacuum is strengthening that well-deserved reputation by offering a wide array of vacuum pumps and aftermarket services to meet your needs. This brochure is meant to provide an easy to read overview covering the entire range of vacuum technology and is inde- pendent of the current Oerlikon Leybold Vacuum product portfolio. The presented product diagrams and data are pro- vided to help promote a more comprehensive understanding of vacuum technology and are not offered as an implied war- ranty. Content has been enhanced through the addition of new topic areas with an emphasis on physical principles affecting vacuum technology. To us, partnership-like customer relationships are a funda- mental component of our corporate culture as well as the continued investments we are making in research and development for our next generation of innovative vacuum technology products. In the course of our over 150 year-long corporate history, Oerlikon Leybold Vacuum developed a comprehensive understanding of process and application know-how in the field of vacuum technology. Jointly with our partner customers, we plan to continue our efforts to open up further markets, implement new ideas and develop pioneer- ing products. Cologne, June 2007 1 Fundamentals of Vacuum Technology 2 Preface Fundamentals of Vacuum Technology revised and compiled by Dr. Walter Umrath with contributions from Dr. Hermann Adam †, Alfred Bolz, Hermann Boy, Heinz Dohmen, Karl Gogol, Dr. Wolfgang Jorisch, Walter Mönning, Dr. Hans-Jürgen Mundinger, Hans-Dieter Otten, Willi Scheer, Helmut Seiger, Dr. Wolfgang Schwarz, Klaus Stepputat, Dieter Urban, Heinz-Josef Wirtzfeld, Heinz-Joachim Zenker 3 4 Table of Contents 1. Vacuum physics Quantities, their symbols, 2.2 Choice of pumping process . .60 units of measure and definitions . .9 2.2.1 Survey of the most usual pumping processes . .60 1.1 Basic terms and concepts in vacuum technology . .9 2.2.2 Pumping of gases (dry processes) . .62 1.2 Atmospheric air . .13 2.2.3 Pumping of gases and vapors (wet processes) . .62 1.3 Gas laws and models . .13 2.2.4 Drying processes . .64 1.3.1 Continuum theory . .13 2.2.5 Production of an oil-free (hydrocarbon-free) vacuum . .65 1.3.2 Kinetic gas theory . .13 2.2.6 Ultrahigh vacuum working Techniques . .65 1.4 The pressure ranges in vacuum technology and 2.3 Evacuation of a vacuum chamber and determination of their characterization . 14 pump sizes . .66 1.5 Types of flow and conductance . .15 2.3.1 Evacuation of a vacuum chamber 1.5.1 Types of flow . .15 (without additional sources of gas or vapor) . .66 1.5.2 Calculating conductance values . .16 2.3.1.1 Evacuation of a chamber in the rough vacuum region . .67 1.5.3 Conductance for piping and openings . .16 2.3.1.2 Evacuation of a chamber in the high vacuum region . .68 1.5.4 Conductance values for other elements . .18 2.3.1.3 Evacuation of a chamber in the medium vacuum region . .68 2.3.2 Determination of a suitable backing pump . .69 2. Vacuum Generation . .19 2.3.3 Determination of pump-down time from nomograms . .70 2.1 Vacuum pumps: A survey . .19 2.3.4 Evacuation of a chamber where gases and 2.1.1 Oscillation displacement vacuum pumps . .20 vapors are evolved . .71 2.1.1.1 Diaphragm pumps . .20 2.3.5 Selection of pumps for drying processes . .71 2.1.2 Liquid sealed rotary displacement pumps . .20 2.3.6 Flanges and their seals . .73 2.1.2.1 Liquid ring pumps . .20 2.3.7 Choice of suitable valves . .73 2.1.2.2 Oil sealed rotary displacement pumps . .21 2.3.8 Gas locks and seal-off fittings . .75 2.1.2.2.1 Rotary vane pumps (TRIVAC A, TRIVAC B, TRIVAC E, SOGEVAC) . .21 3. Vacuum measurement, monitoring, control 2.1.2.2.2 Rotary plunger pumps (E Pumps) . .23 and regulation . .76 2.1.2.2.3 Trochoid pumps . .24 3.1 Fundamentals of low-pressure measurement . .76 2.1.2.2.4 The gas ballast . .24 3.2 Vacuum gauges with pressure reading that is independent 2.1.3 Dry compressing rotary displacement pumps . .27 of the type of gas . .77 2.1.3.1 Roots pumps . .27 3.2.1 Bourdon vacuum gauges . .77 2.1.3.2 Claw pumps . .31 3.2.2 Diaphragm vacuum gauges . .77 2.1.3.2.1 Claw pumps with internal compression for the 3.2.2.1 Capsule vacuum gauges . .77 semiconductor industry (“DRYVAC Series”) . .33 3.2.2.2 DIAVAC diaphragm vacuum gauge . .78 2.1.3.2.2 Claw pump without internal compression for chemistry 3.2.2.3 Precision diaphragm vacuum gauges . .78 applications (“ALL·ex”) . .35 3.2.2.4 Capacitance diaphragm gauges . .78 2.1.4 Accessories for oil-sealed rotary displacement pumps . .38 3.2.3 Liquid-filled (mercury) vacuum gauges . .79 2.1.5 Condensers . .38 3.2.3.1 U-tube vacuum gauges . .79 2.1.6 Fluid-entrainment pumps . .40 3.2.3.2 Compression vacuum gauges (according to McLeod) . .79 2.1.6.1 (Oil) Diffusion pumps . .41 3.3 Vacuum gauges with gas-dependent pressure reading . .81 2.1.6.2 Oil vapor ejector pumps . .43 3.3.1 Spinning rotor gauge (SRG) (VISCOVAC) . .81 2.1.6.3 Pump fluids . .44 3.3.2 Thermal conductivity vacuum gauges . .82 2.1.6.4 Pump fluid backstreaming and its suppression 3.3.3 Ionization vacuum gauges . .83 (Vapor barriers, baffles) . .44 3.3.3.1 Cold-cathode ionization vacuum gauges 2.1.6.5 Water jet pumps and steam ejectors . .45 (Penning vacuum gauges) . .83 2.1.7 Turbomolecular pumps . .46 3.3.3.2 Hot-cathode ionization vacuum gauges . .84 2.1.8 Sorption pumps . .50 3.4 Adjustment and calibration; DKD, PTB national standards . .86 2.1.8.1 Adsorption pumps . .50 3.4.1 Examples of fundamental pressure measurement methods 2.1.8.2 Sublimation pumps . .51 (as standard methods for calibrating vacuum gauges . .87 2.1.8.3 Sputter-ion pumps . .51 3.5 Pressure monitoring,control and regulation in 2.1.8.4 Non evaporable getter pumps (NEG pumps) . .53 vacuum systems . .88 2.1.9 Cryopumps . .54 3.5.1 Fundamentals of pressure monitoring and control . .88 2.1.9.1 Types of cryopump . .54 3.5.2 Automatic protection, monitoring and control 2.1.9.2 The cold head and its operating principle . .55 of vacuum systems . .89 2.1.9.3 The refrigerator cryopump . .56 3.5.3 Pressure regulation and control in rough and medium 2.1.9.4 Bonding of gases to cold surfaces . .56 vacuum systems . .90 2.1.9.5 Pumping speed and position of the cryopanels . .57 3.5.4 Pressure regulation in high and ultrahigh vacuum systems . .92 2.1.9.6 Characteristic quantities of a cryopump . .57 3.5.5 Examples of applications with diaphragm controllers . .93 5 Table of Contents 4. Analysis of gas at low pressures using 5.5.1 Halogen leak detectors (HLD 4000, D-Tek) . .116 mass spectrometry . .95 5.5.2 Leak detectors with mass spectrometers (MS) . .116 4.1 General . .95 5.5.2.1 The operating principle for a MSLD . .117 4.2 A historical review . .95 5.5.2.2 Detection limit, background, gas storage in oil 4.3 The quadrupole mass spectrometer (TRANSPECTOR) . .96 (gas ballast), floating zero-point suppression . .117 4.3.1 Design of the sensor . .96 5.5.2.3 Calibrating leak detectors; test leaks . .118 4.3.1.1 The normal (open) ion source . .96 5.5.2.4 Leak detectors with quadrupole 4.3.1.2 The quadrupole separation system . .97 mass spectrometer (ECOTEC II) . ..