Hi,

The exposure wavelength and the collimation of the exposure light is
critical to get a clean development particularly to resolve
high-aspect-ratio features. You should also check the optial
characteristics of your substrate or any thin metal film on the
substrate at the exposure wavelength you used.   Surface with a
reflectivity at the exposure wavelength can also result in
exposure and developing problem.

regards

Han

> -----Original Message-----
> From: Nan Xie
> Subject: [mems-talk] SU-8 Developing Issue, advice required
>
> 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.