Trupti,

What are your process conditions?  Polymer formation is to the square of the
pressure.  Lower pressure = lower polymer.

John Hall


-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of trupti shantaram khaire
Sent: Sunday, April 22, 2007 5:28 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Nb RIE using SF6

Hi,
I am trying to etch Nb with SF6. I noticed that there is lot of polymer
formation on the Si Substrate surrounding my desired Nb feature. I was
thinking of using SF6+O2 to avoid polymer formation. Adding O2 to SF6 means
photoresist will be etched at a greater rate. It also means that polymer
which is most likely acting as a etch stopper for Si will in its absence
cause Si to etch faster, which is even more detrimental because it will end
up in making a big trench next to Nb feature.(I already noticed the Si etch
of 500nm in 4 min)
Any alternative that anybody knows to avoid Si etch?