Nan,

I often see thus issue when I use thicker layers.  Like Hongjun, I use IPA to
rinse after developing.  The solution to the problem, for me, is to spray a
stream of developer at the white material then throw it back into the developer
for a few more minutes.  Repeat  this till it is gone.  I do not see any
noticable degradation in my structures with increased develop time.  I believe
the instructions from microchem mention this white stuff.

good luck,

Dwayne Dunaway


Nan Xie  wrote:

I am developing SU-8 2050 after spun around 50um.
My procedures for soft baking, exposure, and PEB are correct.
I am having trouble getting clean develops after about 6min and 2-3s acetone
spray.
What I am getting are some milky residue around my features. I understand I need
to develop it more when this occurs, but this milky residue still remains or the
SU-8 would come off.

Anyone have any suggestions? Maybe I need to expose more?