Portland Community College | Portland, Oregon

This course is designed as and introductory and/or reinforcement of the concepts and equipment used in the high-vacuum systems used in semiconductor processing. It will use a laboratory environment to explore the impact of vacuum theory without delving into the technical details of the theory. Students will learn how vacuum systems and components should behave so that they can troubleshoot and repair them.

On completion of this course the student should be able to:
1. Discuss safety concerns and precautions associated with vacuum systems.
2. Describe the normal operation behavior of the following vacuum components:
1. Roughing pumps
2. High vacuum pumps
3. Gauges
4. Valves
5. Seals, bellows and pass-through
3. Describe the basic relationships between pressure, temperature, gas flow, pump rates, and leaks, as they pertain to vacuum systems
4. Describe mean free path, its relationship to pressure, and its impact on processes
5. Perform the following:
1. Leak detection
2. Construct valve sequences
3. Assemble and disassemble vacuum components
4. Calibrate gauges
5. ROR
6. Baseline a tool

This course will focus on laboratory activities. Concepts will be introduced in the laboratory, then demonstrated by the students. The course may include some reading and homework assignments which the students are expected to complete. The laboratory portion of the course meets twice for 5 hours per meeting.

Assessment of student performance in this course will be conducted in both the lecture and laboratory portions of the course and may be in the form of written and /or practice-based questions, and competency demonstrations.

The following concepts will be introduced:
0.0 Vacuum safety
1.0 Gas Properties
1.1 Define the terms: pressure and vacuum.
1.2 Convert pressure units between the following systems of units: torr, pascal, mbar, atm, and mm of Hg.
1.3 List the gaseous components and percent composition of air (excluding water vapor as a component).
1.4 Define the term "Standard Temperature and Pressure" or STP.
1.5 List the four different pressure ranges of vacuum systems: low, medium, high, and ultra-high.
1.6 State the relationship of vacuum ranges to semiconductor processes: photolithography, etch, diffusion, deposition, ion implant, metallization, metrology.
2.0 Gas Flows
2.1 Define the terms: throughput and conductance.
3.0 Gas Sources
3.1 Define the following terms: volume gas, surface gas, and monolayers.
3.2 Give examples of where volume gases, surface gases, and monolayers occur in a vacuum system.
3.3 Relate surface gas composition variations to pumping time.
3.4 Define the term: rate-of-rise.
3.5 Define the term: outgassing.
3.6 Identify materials that are the major sources of outgassing in vacuum systems.
3.7 Describe the effects of outgassing and contamination on vacuum system performance.
4.0 Vacuum Systems
4.1 Sketch and describe the mechanical operation of the following mechanical pumps: rotary oil-sealed mechanical pump, dry pump, and lobe pump.
4.2 Give the operating pressure range and operating principle of the following low-vacuum gauges: absolute pressure gauge, diaphragm gauge, capacitance manometer, thermocouple gauge and convection gauge.
4.3 State the operating pressure range for the following high vacuum pumps: turbomolecular pumps, cryo pumps, diffusion pumps, cryo panels and cryo traps, and getters.
4.4 Give the operating pressure range and operating principle of the following high vacuum gauges: cold cathode ionization gauge and hot cathode ionization gauge.
4.5 Describe how gas loads affect pumps
5.0 Leak Detection
5.1 Describe the following types of leaks; real leaks; seal surface integrity,: virtual leaks.
5.2 Vacuum Trouble shooting techniques.
5.3 Demonstrate troubleshooting skills by systematic leak detection using helium gas.
5.4 Relate leak rate to standard cc/sec.
5.5 Define the term: virtual leak.
6.0 Residual Gas Analyzer
6.1 State the purpose of a residual gas analyzer.
6.2 Analyze a mass spectrum in a typical vacuum situation.
7.0 Vacuum Components and Materials
7.1 Describe the operating principle and best usable pressure range of the following fittings: O-Ring, Conflat flange, K-flange, and Swagelock.
7.2 Describe the operating principles and correct operation of the following valves: Regulators, Nupro pneumatic, needle valve, throttle value, swing gate, and sliding gate.
7.3 Describe basic lubrication processes, fluid rheology and techniques for vacuum lubrication.
7.4 Describe vacuum sealing and joining techniques: welded and brazed metal joints, metal, glass and ceramic joints, elastomer and metal-sealed flanges, valves, and motion feed-throughs.