Hi Tom,

The standard spin coating technology produces highly uniform layer on a
planar surface.
However, in the case where wafer through-holes, pyramids, walls, grooves  or
"high-aspect structures" are present, the coating is rich in striations and
holes are filled with photoresist. On such coating, lithography could not be
successfully performed. I would tend to recommend a technique with
electrodepositable photoresist (Shipley ED Eagle 2100 or Pepr 2400) or our
electro-spray coating technique, which allows uniform photoresist coverage
(resist thickness varies with the deposition time and is typically adjusted
between 1µm and 2µm, which is similar to conventional spin-on coating) on
highly textured surfaces and makes subsequent lithography steps possible.

For more information
please feel free to contact me.

With best regards
Andreas



Andreas Scheipers
D-48308 Senden
Germany
andreas.scheipers@t-online.de
Tel.: +49 (0) 2597 96 762
Fax: +49 (0) 2597 96 769



----- Original Message -----
From: "Tom Fan" 
To: 
Sent: Wednesday, August 13, 2003 2:15 AM
Subject: [mems-talk] Electrodes in Microchannel


>
>
>
> On the same topic, would 4-um high structures (serving as electrodes)
standing
> on otherwise flat substrates be considered "high-aspect-ratio" structures?
> Would conventional resist spin coating process do the job? And also can
the
> lithographic tool handle a height difference of 4 um (if exposures on and
off
> the structures are desired)?
>
>
> Thanks,
> Tom
>
>