Patrick,

you may want to use the good old straw pipe to clean the edge bead, while
on the spinner-its a bit tricky though!  alternatively you may want to do
an additional lithographic step and expose and develop a ring that removes
the edge bead.  Both worked okay for me but i had a preferance for the latter.

hope this helps

Shekhar



At 02:46 PM 1/31/00 +1000, Patrick Leech wrote:
>Dear Colleagues,
>I would like to know of a simple and effective way of removing the edge
>bead after spinning of AZ4620 resist on a 3" silicon wafer. At present,
>after spinning at 4,000 rpm, a 2-3 microns lip of resist develops around
>the rim of the wafer.
>
>Thank You,
>
>(Dr.) Patrick Leech,
>CSIRO Division of Manufacturing Science and Technology,
>Private Bag 33, Clayton South MDC,
>Victoria, Australia, 3169.
>
>