Subject: IMPORTANT: EHT Trip was encountered this weekend on RAITH at 15 kV. Please Bake your samples!!!!
From: James Conway <jwc@snf.stanford.edu>
Date: Mon, 17 Jul 2006 11:47:10 -0700

["multipart/related" not shown] Mon, 17 Jul 2006 11:47:10 -0700

Subject: IMPORTANT: EHT Trip was encountered this weekend on RAITH at 15 kV. Please Bake your samples!!!!
From: James Conway <jwc@snf.stanford.edu>
Date: Mon, 17 Jul 2006 11:47:10 -0700



Greetings Raith Users,



Over the weekend, there were several User induced Load Lock ERRORS that brought the system down until I was reached losing about five working hours on the system

Later this last weekend, despite excellent vacuum in the Gun Section of the RAITH Column and due diligence running in the new FEGun over the course of last week; we encountered a EHT Trip and Gun arcing event on the system. This was encountered some time after the load lock procedure was completed and starting of the EHT power applied to the FE-Gun. It occurred while the user was imaging and scanning across his sample with the SEM.

THE USER HAD NOT BAKED OUT HIS SAMPLE ON A HOT PLATE!
[ Link to my previous message ]

Likely some gas was adsorbed into the sample film(s) and then they desorbed upon Ebeam exposure on the sample rapidly raising the system pressure and then the gun pressure.  The system's EHT power supply sensed the beginning of an arc event and trip off the EHT supply and shut down the FE-Gun.  It was necessary to perform the service Gun ramp up to bring the gun back up and subsequently it was found the detector configuration and the L-REM modules on the SEM had been corrupted. This required system admin. support to recover.

Finally the User attempted a "reset' but not a 'SHUT DOWN' of the computers to reset the hardware and initially was unable to recover any detector functionality.
A 'SHUT DOWN' was then performed and the detectors configurations were reinitialized and the L-REM SW module reloaded.
The system came back up after about four hours of being off line and more than three hours of phone support to correct the mess.


Lessons Learned:

HOLD THE DOOR DOWN ON THE LOAD LOCK WHEN IT STARTS PUMPING.
SOFT BAKE your Samples if they are not fresh off a hot plate or oven.  Bake at 90 degrees C for 2 minutes on any hot plate and load immediately.
Always reset the RAITH and LEO computers by employing 'Shut Down' and never 'Reset' of the windows operating system on both computers.

This afternoon I will again begin my testing of the system at 10 - 15 kV range to determine if other problems exist. I will be examining the Gun Vacuum pressure and the diameter of the RAITH Electron Beam's diameter looking for changes from Friday afternoon.

Please be careful when you are working on the system!  Many Users are depending on its good performance.

Thank you for your support!

James Conway


Mon, 17 Jul 2006 11:47:10 -0700

Subject: IMPORTANT: EHT Trip was encountered this weekend on RAITH at 15 kV. Please Bake your samples!!!!
From: James Conway <jwc@snf.stanford.edu>
Date: Mon, 17 Jul 2006 11:47:10 -0700

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