Subject: RAITH STATUS AND notice of change in Limitations of Acceleration Voltage: No Operation above 20 kV.
From: James Conway <jwc@snf.stanford.edu>
Date: Fri, 04 Feb 2005 09:28:05 -0800

RE: 2005-02-04 09:00:14: NO OPERATIONS ABOVE 20 KV

Greetings:
I have cleared the previous comment in the RAITH maintenance section on Coral and am increasing the limitation of Acceleration Voltage from 10 kV to 20 kV.  The beam spot profile and emission levels are stable and approaching the target value for the new FE-Gun tip.

This week's highlights:
The smallest contamination dot shot observed in training sessions this week was 10 - 11 nm.
The short spot contamination dot using the left hand mouse button trigger on the icon has been observed s small as 13 nm. Careful focusing and stigmation are required.
The smallest single pixel line obtained last week during PCM testing was 17 nm.

The FE-GUN is approaching optimal conditions for Ebeam writing.
Emission Extraction I level with  EHT 'off'  is 99.7 uA and EHT 'on' is 82 uA yielding a delta of  17.7% which is optimal for the gun set up on the system.  The Emission continues to very slowly increase with continued operations and run in time. Beam Current stability measured over the course of two to three hours is better than expected and would exceed the specification of less than 0.5% beam drift over 40 hours of time.  We have a very nice FE-tip and operation conditions for Ebeam Lithography.

ALL Users are requested to be very conservative in their work and I recommend you give the system a slight period of additional pumping time after loading their samples into the system before bringing up the EHT.  This will allow your samples to continue to  outgas upon loading into the sample chamber and upon initial exposure to the ebeam allowing the chamber to rapidly reach its base pressure.
Gun Vacuum EHT 'off' is 7.7E-010 Torr and Chamber base pressure has been observed to be 1.2E-006 torr within one hour. 

Users are requested to carefully inspect their EBL patterns before pattern transfer and immediately report problems aberrations or concerns to James Conway and the RAITH discussion list.
 We continue to observe normal levels of scattering or blanker leakage through the aperture plates in the column during blanked operations and you may see artifacts of this emission if you dwell for long periods of time in one spot or write within a single write field for long periods of time. The emission scattering levels remains the same as before the PM routine at 0.0005 nA and is below specifications for the system. (1% of unblanked Beam Current measured in the faraday cup.)

Thank you for your support!

James Conway