Edge Bead Removal
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
- 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
- Over expose (to make
sure all the resist is removed from the area during develop)
- 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
- You should find that the outer
5mm of resist has been removed and that your pattern on the rest of the
wafer is fine.
Stanford Nanofabrication Facility