If you are trying to release SU-8, you may find these two papers useful:

Reinforcement of PDMS masters using SU-8 truss structures.
http://iopscience.iop.org/0960-1317/15/6/023

Fabrication and application of silicon-reinforced PDMS masters.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V44-4K717YH-1&_user=1
08428&_coverDate=10%2F31%2F2006&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&
_sort=d&_docanchor=&view=c&_acct=C000059731&_version=1&_urlVersion=0&_userid=108
428&md5=17e6f5e170e1bbeae97ac62ebf6838a0&searchtype=a

Thanks and regards,
Anirban Chakraborty
Post Doctoral Research Associate
Mechanical and Aerospace Engineering
University of Texas at Arlington, TX USA

> From: Aarthi lavanya 
> To: "mems-talk@memsnet.org" 
> Date: Fri, 15 Apr 2011 14:01:51 +0800
> Subject: [mems-talk] Si Etch with KOH
> Hi,
>
> I have structures sitting on Si wafer and it is covered with layer of Su-8.
The main idea is to etch away Si and have a Su-8 layer with structures on it.
>
> I've been trying to etch Si using KOH and always end up with gooey looking
liquid and the Si looking all messed.
>
> Suggestions please ..
>
> Cheers
> Aarthi