Vacuum Physics Laboratory

You should read this brochure before your lab.

Instructions

Mechanical pump only

1. Connect a thermocouple gauge directly to the pump and determine the ultimate attainable pressure using the mechanical pump.

2. Connect the mechanical pump directly to the main vacuum chamber. Measure the pressure as a function of time and determine the ultimate attainable pressure. Properly model the time dependence of the pressure. You will need to come up with a physical model of the vacuum system and test your model against the results you obtain.

3. Close the gate valve and measure the time dependence of the pressure. Model the vacuum system to determine if it the chamber is leaking or outgassing. Estimate the leak or outgassing rate quantitatively.

Mechanical and diffusion pump

0. Understand the pumping system: before turning on the system, demonstrate to Masa how you will perform Steps 1-9.

1. Isolate diffusion pump and vacuum chamber.

2. Use mechanical pump to pump the diffusion pump down to 10 millitorr.

3. Before turning on diffusion pump, ensure that the cooling water is running. Water valve is on the wall. Turn open water inlet and outlet valves.

4. Turn on diffusion pump heater. Monitor the pressure inside the diffusion pump as a function of time.

5. Isolate diffusion pump and use mechanical pump to pump down the vacuum chamber.

6. Make sure to not let diffusion pump isolated for too long without pumping using the mechanical pump

7. Once the vacuum chamber reach the ultimate pressure for the mechanical pump, switch the valves so that the mechanical pump backs the diffusion pump, and open the gate valve between the diffusion pump and the chamber.

8. Once the vacuum chamber reaches the ultimate pressure for the diffusion pump, close the gate valve and measure the pressure change as a function of time. Model the vacuum system to determine if it the chamber is leaking or outgassing. Estimate the leak or outgassing rate quantitatively.

9. Get the vacuum pressure back down to 1e-6 torr or below. Before reopening the diffusion pump gate valve, consult the instructor on the correct procedure to use. If the chamber pressure has risen above 1e-2 torr, it might be prudent to pump the chamber using just the mechanical pump before opening the diffusion pump gate valve again.

10. After the chamber has been pumped below 5e-6 torr. Operate residual gas analyzer (RGA).Do not turn on RGA unless the chamber pressure is below 5e-6 torr. Here is the manual.

Residual gas analysis

1. Analyze the residual gas in the chamber

2. Come up with a proper strategy to find a potential leak in the chamber using the RGA.

3. Check for leaks in the chamber.

4. Are there alternative ways to check for leaks in the chamber?

Metallization Lab

1. Find a proper procedure to pump down the deposition chamber with aluminum as the evaporated material.

2. Once pressure is down to desired level, deposit aluminum film on glass slide. You will probably use this film in other lab so keep the film in tact.