Sounds like reflections from the back of the glass
Shay

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Herman Walgraeve - TNW
Sent: Friday, June 08, 2007 5:19 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] 2.5 um microchannels in SU-8

Hi,

The smallest design features I want to create are 2.5 um channels made
by SU-8 25 resist (thickness about 10 um) on AF45 glass wafers.
I use near-UV lithography.
I can not open the channels during development (5 min. stirring ; mr-DEV
600 developer is used). 5 um channels are formed without any problem.

I know 2.5 um is close to the near-UV resolution limits, but is this
really a lithographic issue or maybe a development issue?