Stage Modifications

Background

The "bar" for tip transfer holder is in the center of the sample area and has a significant negative effect on Auger performance, particularly at low voltages.

Also Ion Sputtering is affected.

There are issues with beam current (SCM) measurement. Sometimes this works well, sometimes sample is grounded.

Modifications

Check exact electrical conditions (what metal parts are at what potentials. 

• Each spring clip separately connected to external leads.
• "U shaped" body not grounded at all (except by our previous mod)
• Attachment screws for ceramic clip holders (2x2) and U mount (2x2) isolated from U part, floating.
• Thermal clip hard grounded to chamber
• Clip screws connect to U part.

Changes

• Remove bar and and kapton insulator washer so left clip at U potential.
• Right clip still isolated when no sample plate in place
• Ground all floating screws to U part (tack on grounds with spot welder)
• Add new bar on receiver guide to U part, same side as original but ~ 8 mm back
• Extended back of tip carrier spring to engage new bar, removed most of original bar catch.
• Verify modified tip carrier works for airlock-transfer arm-carousel-stage transfer
• Verify piezo motors

Bakeout

• All turbos running, transfer gate between chambers closed, gun valve open also bypass
• Pump down to 9.5e-6 nano 1.6e-6 prep then start bakeout
• Shut down ion pumps, open gate valves (were closed for up-to-air)
• Start 48 hour bake 5 pm friday 3/8/13
• 3/9/13 10 pm: 6.5e-5 nano, 6.5e-6 prep.
• 3/10/13 2 pm: 3.5e-5 nano, 3.1e-6 prep.

during bake

• Start 5 pm Friday, at noon on Saturday ion gun turbo goes off - no apparent cause. Gate valve closes before bakeout interrupted
• Air temp reaches max at 11 pm Fri, switches off 2 pm Sunday (for 48 hour bake).
• Flange reaches 140 after 5 hours, 180 after 11, cools to 70 C in 11 hours after heat off
• Programmed bake temp is 150 C but air temp goes to 190+/- 5 C, SCA flange reaches 187. 
• Unexplained pressure spike 7:45 am in nano chamber, 6e-9 to 2e-5, recovers by 9 am