Hi

I wouldn't recommend refrigerating your SU-8. This will increase the
viscosity and may result in a thicker than expected layer which would
then increase the required baking parameters. Have you checked your
layer thickness is as expected?

As for exposure dose, my recent experience is that you need
dramatically more than the datasheets recommend when using a filtered
source. 40% may not be enough - 400% may be more like it! I don't know
if this will have any influence on sticking to the mask though.
Some people break their exposure up with gaps, to prevent heating of
the SU-8 which may also lead to sticking of the mask. This could be
worth considering, especially if you don't have any IR filter (I think
most mask aligners do).

Best regards

Gareth


On Wed, Oct 22, 2008 at 02:18, 郑瑞麟(Ruilin Zheng)  wrote:
> Hi,
> Thank you all for the advice!
>
> I checked my hotplate, and I think it works ok, because I found that the the
> SU-8 layer shrunk a lot and the edge of silicon wafer appeared after
> soft-bake, when I used higher soft-bake dose.
> The exposure dose should be reduced than that without Omega UV filter, but I
> also tried to increase the exposure time by 40%.
> The problem has not been solved yet.
> Can this problem have something to do with the photoresist itself?
> The SU-8 I am using is stored in a small bottle ( sealed but not very well )
> instead of the original bottle, and put in the refrigerator (several degree
> above zero) for over two months.
>