I don't think dyed resist will fix your problem. You shouldn't need a dyed
resist on SOI and oxide. Most photoresists have some dye in them. Some much
more than others, but heavily dyed resists are usually only needed on highly
reflective layers such as metal layers.

Robert

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Mihaela Carp
Sent: Thursday, May 03, 2007 2:58 AM
To: mems-talk
Subject: [mems-talk] Oxidize wafer SOI for litho pattern

Hi, all!

I have an SOI wafer (2µm+0.5µm+380µm) with 50 nm oxide on top
and I have problem patterning them.

I used without problems this litho process: deposition of AZ9260 5 micro,
trat 110°C 4 min, exp 20 s, 9.3 mW/cm2, develops 50+10 s for other
wafers. I try also thinner photoresist 1.5 µm with 3.3 s exposure time
but without success. The pattern looks unclear and over expose. I try to
reduce the exposure time (until 10 s) but the result is unchanged.

I found on net that somebody used ink to reduce the reflectivity but I don't
find what type of ink and I'm concerned about the chemical reaction with the
oxide etcher solution after that.

Do any of you know about commercially available ink for this kind of
purposes? Can you suggest me other solutions?