Hi everyone,

I am using standard techniques for fabricating SU8 mould for
microfluidic PDMS devices, but i am having troubles obtaining a correct
aspect ratio.

  Does anyone have some tips to achieve a:
- 50 µm height
- 10 µm width pattern
- a 0 - 3 µm variation in width of the pattern between substrate and the
top.

The resolution of the mask (SELBA, Switzerland) is checked and good, I
am working in hard contact, and use a 365 nm i-line filter for the exposure.
I may think this is related to diffraction, would you suggest to use:
- under exposure?
- flash exposure?
- other ideas??

I also tried multi layers to minimize the diffraction effect on each
step, but the pattern is particulary difficult to align (big area and
small parallel patterns..)

Thank you for your help!

Antoine Blin

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