Raith: interesting (important?) discovery

Mark Topinka mtopinka at stanford.edu
Mon Jul 4 01:46:05 PDT 2005


Hi-  if anyone is continuing to have problems with part(s) of their pattern 
being blurry or not exposing at all, while the rest of it seems fine, 
please contact me asap.  I think I've figured out a work-around, even 
though I still don't understand the underlying hardware problem.  As best I 
can tell, this is not happening because of a leaky beam blanker.   Rather, 
it seems that after a long time being blanked (like, between writefield 
moves), the beam is out of focus and/or low in beam current  for the first 
roughly 0.01-0.1 seconds after being unblanked (+ or - a factor of ten, 
probably - I haven't measured it carefully, and it probably depends on lots 
of things).    Short blankings, like between dots or objects within one 
writefield don't affect it, so after the initial "warm-up" time in each 
writefileld, my experience has been that the rest of the pattern writes 
great.  The (hack) solution that I found is to make a sacrificial object in 
each writefield that takes about a second to write and is the first thing 
that gets written.  (Use the "O" command in the raith pattern editor to 
order your objects  so that it is the first object written, otherwise it 
does no good).  I have no idea *why* the raith is doing this.  Has anybody 
else continued to experience these problems (even after the column 
replacement?) or have I been the only one?  -Mark
  




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