Try spray coating.  You may be trapping air if using spin coating.

Good luck,
Suzanne

-----Original Message-----
From: Black, Robert [mailto:r-black1@ti.com]
Sent: Monday, October 27, 2008 8:04 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Filling deep vias with resist

     I'm trying to fill some deep vias (25um wide, 70um deep) with resist. I
can't seem to get the resist to go any deeper than about 40um. The best
results were with using a PGMA pre-wet.  I've tried some 55cp resist that I
coated three times to fill (based on top down zygo) and some 120 cp resist.
X-sections show both resists to only be 40um down the vias.
    Any suggestions?

Robert