[mems-talk] Nb RIE using SF6

[trupti shantaram khaire]

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????? 
Thanks!
~T