Hello, everyone,

I am doing some fabrication work with SU-8 2150 ultrathick layer, up to 400
microns at a single layer spin coating.
Because I just start my work, so there are a lot of problem stay in my way.
After scanning the sidewall with laser scanning microscopy, I found that the
side wall profile is partially vertical. At the part near the substrate up
to about 1/3 of its height, the profile is concave.

>From 1/3 to total height (up to surface ), the profile is fairly vertical.
The difference between the concave part and the vertical part is about 40
microns.  The UV source I am using doesn't have a filter for UV-light, so
it is not a very coherent source.

Does any one meet this problem before? Please give me some advice.
Thanks a lot!

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Best Regards,

Ruilin Zheng