mahnaz at stanford.edu
Fri May 21 10:53:20 PDT 2010
I will be on vacation next week so here are some information on the
tool in general which I hope to explain little more details.
I will put a copy of it in the lab and when Uli is back we will add it
to our training procedure.
Let me explain to you the differences between the three buttons, Align
*Check and Exposure key and this may refresh things.
1. The Align Cont/Exp. key is used to bring the wafer into Contact
from the Alignment gap and/or back to the Alignment gap from Contact.
2. The Alignment Check key is used after the alignment of the mask
and wafer, it brings the wafer into contact and is used in cases with
exposure programs like Hard Contact or Vacuum Contact where vacuum
that typically holds the wafer to the chuck is released during the process to
provide a more intimate contact to the mask. This key performs the
complete exposure program except for exposing the wafer. This option
is convenient because one can see a shift, realign if necessary, and all of
this can be done with out exposing their wafer.
3. The Exposure key is used after the alignment of the mask and wafer,
brings the wafer into contact, performs the complete exposure program
and exposes. There is no chance to realign is a misalignment occurred
during the exposure program.
As for Soft Contact misalignment issue that Tom is experiencing, the
potential for a shift to occur is much, much less than that of a Hard
Contact program as the wafer vacuum is present during the entire process.
So Now I have two options:
I like to sit next to Tom and see what is happening ( Tom knows the system very well so the
chances of him doing things oddly is very little.
This is an intermittent issue ( i believe that, and I have seen it)
should the system be evaluated? Yes, I think so.
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