Exposure with <340nm leads to negative sidewall slopes rather than
postive which is the observed problem unless I misread it.
Abhishek, are the structures 30um at the top and 60um wide at the
bottom? If it's the other way round (60 at the top, 30 at the bottom)
then a filter could indeed be the answer.


Nodes Norbert wrote:
> Is there any UV filter installed in the lamp house?
>
> Exposure of SU-8 should not be done with UV light less than 340nm
> wavelength.
>
> Shorter wavelengths would create cracks in the resist layer and cause
> problems regarding sidewall angle.
>
> i-line exposure is recommended by resist vendor.
>