Problem raith 2004-02-11 09:21:26: beam current falling -- PM will occur next Friday - Tuesday.

[James Conway]

Greetings:

The beam current values (BEAM I) have been falling consistently as the 
10 and 30 um apertures are becoming blocked with hydrocarbons during the 
writes.  This is normal and is to be expected especially considering the 
usage we have on the system.

Currently the beam current for the 10 um aperture is 50% of when the 
aperture disk was new.
Currently the beam current for the 30 um aperture is 60 % of when the 
aperture disk was new.

50 % of new maximum is the breakpoint to trigger the PM request.  As 
planned and previously announced,  we will be doing a column clean with 
aperture replacement PM including a NEW FE-gun tip replacement this next 
weekend. We will be down Friday 10 AM through late Tuesday afternoon. No 
access no use during this period.  40 hour bake out has been requested 
and will be done concurrent with the Monday Holiday.

The system will be requalified for performance and imaging resolution 
before releasing it back to users.  Please schedule your work accordingly.

The report of the stage freeze is the first reported in some time...  we 
will monitor the situation.  If you observe this give time for all macro 
and other operations to be completed then attempt to move the stage a mm 
or more using the Stage control.  If this still does work press the STOP 
SIGN in the Stage control window and it will stop all pending operations 
and release the XYZ axis's.

Back to green light mode...  writes performed last night by dwshin came 
ot very nice.

Thank you,

JWC




quay at snf.stanford.edu wrote:

>1) Beam current low and fluctuating *a lot*. Last user (John Paul) records 30pm at 30 micron aperture (compared to 140 usuall). I got 63 +/- 5. At 120 micron aperture,current was 1.252nA and decreased by 0.01 nA over a five minute period. I noticed from the logbook that the current has been steadily decreasing over the past 2 days. 
>2) Column not moving.  After write, joystick did not move column. Nor did software. I managed to 'fix' this by turning off and and on the laser stage control.  I suspect that the column may not have moved at all during the write, i.e. only one writefield was written over and over again.
>John Paul, have you developed your write? Did it look like (2) hapened for you also? 
>Charis.
>  
>