Hi Jiang,

If your spin-coater allows you to drill a hole on the lid above the edge
of your wafer, you can insert a syringe through that hole and dispense
acetone near the end of the spin program. The acetone flow must be low to
avoid splashing onto the wafer. If you can have a control box that can
feedback with your coater electronics, you can have an automatic time
control of the acetone dispension. That's how we do in our lab. You can
contact me for more information.

Yours sincerely,

Isaac Chan, Ph.D.
University of Waterloo

On Tue, 12 Apr 2005, Jiang Ziling wrote:

>   I have been doing lithography for quite a long time but am still
> confused about 'edge bead removal'. My spin-coater has to be closed
> when it is spin-coating and there is edge bead on the wafers after
> coating. Should I just use something like cotton bud to wipe off the
> edge bead on periphery of the wafers? Or is there some clever method
> of avoiding edge bead? Thanks