SU-8 2075 is not the best formulation for coating that thick.  If you
can try SU-8 2100 or 2150. If you cant get this material you are going
to have to do multiple layers ~4 at an rpm of ~ 1000.  You can drop your
spin speed down to 500 or so and decrease your spin time.  This will
increase the thickness quite a bit per layer but your uniformity will
suffer, if your specs aren't real tight this is your best bet.

One thing to keep in mind is you will have to do a bake after each
layer, to prevent any temperature effects such as thermal cross linking
it is best to do ramped bakes at different temperatures.

If you haven't already done so here is the link to MCC data sheets they
will provide more detailed process steps.  In my experience these data
sheets show results closer to those actually observed better then most
vendors.

http://www.microchem.com/products/su_eight.htm

Best Regards,
Mike Sexton

EV Group
invent * innovate * implement
Process Technology Engineer - Direct: +1 (480) 305 2450, Main: +1 (480)
305 2400 Fax: +1 (480) 305 2401
Cell: +1 (602) 625 1275
E-Mail: M.Sexton@EVGroup.com, Web: www.EVGroup.com

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Abhishek Jain
Sent: Sunday, April 13, 2008 9:28 AM
To: General MEMS discussion
Subject: [mems-talk] su8 1000um thick

Dear forum members

I want to make 1mm thick structures on SU8 for doing soft lithography
with PDMS later on. It is only one mask and just straight channels.

I have SU8 2075 with me and I am trying to find a recipe for doing this.
If anyone has experience in dealing with this, I will truly appreciate if
you may give some insight on the method...