Make sure the temperature is not ramped too fast. In particular I would
recommend always allowing the wafer remain on the hotplate whilst
cooling down.
The PEB introduces most stress especially when large areas of SU-8 are
exposed. A lower temperature PEB for longer periods generally gives
better results.
Insufficient exposure dose could also be a cause.

Bin Wang wrote:
> Hi all,
>
> Recently we met a problem on SU-8 adhesion. After a typical SU-8
> process, the ENTIRE SU-8 film peeled off ALL AT ONCE from the Si
> substrate when we developed it. We have dehydrated at 200C for 20
> min before coating. For prebake and PEB, we tried both standard
> length of time and the time 50% longer than the standard, but
> neither worked. Could anyone help me crack this issue? Thanks a
> lot.
>
> Additional info: Wafer cleaned in Nanostrip for 3 hrs before
> dehydration. SU-8 2050 spinned at 2500rpm. We used standard
> exposure time, standard developer and IPA rinsing.