660 Scanning Auger Bake-out procedure.
This procedure is written for the PHI 660 scanning Auger system but also works for the 600 scanning Auger systems as well.
- Ion pumps must be on and the system vacuum should be in the mid to low 10-7 range (or better)..
- Make sure that the card rack power supply is OFF. Also make sure that these units are OFF:
- 20-610 High Voltage Supply
- 20-622 Gun control
- 11-065 Ion gun supply
- Balzers Thermo Valve Control (gas valve also needs to be closed)
- The DIGIII ion gauge control and Boostivac ion pump control should be ON.
- Remove all cables that are above the table top. These include the Auger analyzer, SIMS analyzer (if so equipped), 96A V/F preamp, 1182 or 1120 amplifier discriminator, and the 97 SED preamp. TIP: Make sure that the cables are labeled as you remove them.
- When removing the 97 SED preamp be careful not break the feedthrough pins! Also when you put it back on after the bake-out make sure it is flush with the flange and then use a flat blade screwdriver to tighten the screws – snug plus 1/8 to 1/4 turn.
- Remove the filament cap on the top of the analyzer (3 screws at the base, do not unscrew the cable!).
- All of the cables above the table top should now be removed.
- Remove the wooden tabletops.
- Pull up on the table top switches. Note that in some cases the switches need to be pulled all the way up, but in other cases they may just need to spring up after the table tops are removed. If the bake-out timer does not start, check the table top switches.
- Wipe off any fingerprints from the system with Isopropanol (work it may, shine it must!).
- Cover all of the windows with aluminum foil. Also cover the stage micrometers and any exposed feedthroughs. If you are uncertain – cover it just to be safe.
- Place the bakeout blanket over the vacuum chamber. These blankets have fiberglass in them so use gloves and avoid exposure as much as possible when handling the blanket. Also some of the blankets use metal Velcro – be careful or your arms will get cut!!
- Secure the blanket as well as you can. IMPORTANT: The V1 gate valve should be outside the blanket. Use aluminum foil to seal any gaps in the blanket. If possible cool the V1 gate valve with a small fan.
- Turn off the turbo pump.
- Turn off the Auto Valve Control
- Set the bakeout timer for 8 to 12 hours (8 hours is usually enough)
- Press the bakeout ON button and the ovens should come on. If not, check that the table top switches are not being held down by the blanket.
- The DIGIII setpoint 4 controls the ovens. If the pressure in the system goes above set point 4 (usually 2 to 4 X 10-6 Torr) then the ovens will shut off until the vacuum recovers.
- Once you verify that the system is baking then it can be left unattended until the bakeout is complete.
After the Bake-out.
- After the bakeout is complete, the first step is to remove the bakeout blanket. If the system is still very hot, then open the blanket just a little bit and let it cool down for an hour or two until just warm. Then remove the blanket.
- Install the table tops.
- Turn on the AVC.
- Make sure that the card rack power and all units (20-610, 20-622, 11-065 and Thermo Valve) are still OFF.
- Re-connect all cables and preamps to the system. Use EXTREME CARE when installing the 97 SED preamp.
Once all of the cables have been connected it is safe to turn on the system normally.
It is recommended that the Lab6 filament and 11-065 ion gun control emission current be turned up very slowly the first time that they are used after bakeout in order to give them time to outgas.