Subject: Re: cancelled 9-2 tonight
From: John Paul Strachan <>
Date: Wed, 11 Feb 2004 14:50:15 -0800 (PST)


I think I got lucky and did not have problem 2) reported by Charis,
although we did have the fluctuating beam current problem.  But we just
read the current frequently to get the proper dose.  I developed my
wafer and it looked very good across the whole wafer - so it did not just
write and re-write the same field as may have happened to Charis.

If James is agreeable to the idea, I suggest we follow Charis' suggestion
and open up time so that maintenance can be performed early.

-John Paul

On Wed, 11 Feb 2004, Lindsay Moore wrote:

> also, whatever list is, it does not send email
> to the whole raith list.
>   here is the info from charis:
> 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.
> and james:
> 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,
> and hatice:
> For 30 micron aperture from 11:00 am to 12:30, current changed from from
> 56pA to 63, 68, 113, 128, 110. It does not stabilize, it inreases and
> decreases randomly.