My first suggestion would be to check that your processing of the SU-8 is optimised; the post-exposure bake is critical in reducing stress in the SU-8 film.

Next you could try O2 plasma / UV-ozone to clean and activate the surface.

If your application and process allows for it, could you try a very thin adhesion layer (e.g., Ti, Cr, Al)? Al seems to offer the best adhesion to Au, but it may be didfferent for ZnO:

Article Investigation of the bond strength between the photo-sensiti...

Kind regards,

Jules

Jules Lloyd Hammond thank you very much. Really helpful.

For my application, I cannot add any layer.

Thanks again.

Hello Ahmed,

As stated; the post-exposure bake is very important in reducing stress in the SU-8 film. For larger samples you should make sure you use a hotplate with a good heat capacity (for instance the ceramic tops tend to have a large temperature gradient between the centre and perimeter compared to a hotplate with a solid metal block), you can also use a petridish to cover the samples to help prevent rapid cooling of the sample).

You may find the following article of use;

https://people.rit.edu/deeemc/reference_13/photoresists/bowen_SU8stress_report.pdf

Jules Lloyd Hammond I really appretiate your help. Thanks a lot.