removal of 5mm edge bead using lithography

Sharleen Beckwith beckwith at
Wed Apr 19 10:55:02 PDT 2000


If you need to remove thick resist from the edge of your wafer before using
lampoly, here is an easier way than using the cotton swab/solvent method:

Edge Bead Removal (Masking)

If you will be using dry etchers such as the lampoly and p5000 etchers you
may be required to mask the outer 5mm of your wafers to remove the
photoresist. This prevents problems with the etchers such as the clamp
fingers sticking to photoresist on the top edge of the wafer. The procedure
follows, but contact Margaret Prisbe or Mahnaz Mansourpour for the mask,
and for any questions about the procedure that you may have.


The mask is a 5 inch contact mask. It can be used on either the karlsuss or
the evalign.
After your wafers have been coated and baked use the karlsuss or evalign to
pattern the outer edge of your wafers.
Expose using EDGE EXPOSURE REMOVAL MASK (see Margaret or Mahnaz)
Use soft contact
When you load your wafer, center it so that you get a 5mm removal of resist
on the outside. Expose one wafer, develop it and inspect it before doing
the rest of your wafers.
Over expose (to make sure all the resist is removed from the area during
Then do your normal exposure on whichever alignment tool you normally use
(you will do both exposures, and develop only one time).
Develop your wafers and inspect.
You should find that the outer 5mm of resist has been removed and that your
pattern on the rest of the wafer is fine.


last updated 1/31/00 MAP
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