Hi Zhiyan,

to avoid cracks on SU-8 during development you have to adopt a relaxation
time between the post exposure bake and the development. I made good
experience with waiting overnight. You also have to cool down the wafers
slowly after the softbake and also after the PEB.
The best alternative to prevent cracks is to design the mask without
corners. Because these produce the cracks.

best regards,
Ulrike Schoembs

-----Ursprüngliche Nachricht-----
Von: Zhiyan Liu [mailto:[email protected]]
Betreff: [mems-talk] Cracks on SU-8 during the development

I am trying to use SU-8 with the thickness around 30um. But during the
development in PGMEA, I found cracks created in the SU-8 . Mostly these

cracks are originated from the corner of developed region and extend long
into the SU-8.

I am wondering if someone can give me a comment why these cracks enerated
and how to optimize the process.