Hi,

In my case, after 400mJ/cm2 exposure, only few small cracks appeared on su8
surface. These cracks disappeared after hard bake. I don¡¯t think su8
reflowed during hard bake. But the hard bake did anneal su8 and removed the
small cracks.

About the bubbles, no matter how carefully I operated, there is still one or two
tiny bubbles produced. In my case, this did not matter much, since I only used
su8 as a mask.

There is another thing I do not understand. When I exposed 800mJ/cm2, the su8
can be developed more than 5mins without any cracks. Of course my structure
looks ugly with this exposure dose. On the other hand if I use 400mJ/cm2
exposure, I will get nice features after 2mins developing. But if I keep
developing to 3mins or longer, big and deep cracks show up again. Is this
phenomenon reasonable?  The developing time should be controlled very precisely?

Sonic