We have had some experience of etching Niobium layers, too.  We also used
SF6, but in an ICP system.  This gave an undercut profile initially.  Adding
oxygen helped to passivate the sidewalls (but would not be good for
photoresist selectivity).  We were using hard (PECVD SiO2) masking.  The
etch rate was around 150nm/min.

Martin Walker, Oxford Instruments

>Roger Shile mems-talk@memsnet.org
>Thu, 18 Apr 2002 09:18:12 -07
>I have had success etching Nb with pure SF6 plasma using a March Jupiter
RIE
>system.  The electrode diameter was ~ 6".  RF power was 50 watts.  Pressure
>wass 200 mTorr (?).
>
>1.3 microns of hard-baked resist was more than adequate as a mask to etch
4000
>Angstroms Nb films.
>
>Roger Shile
>
>>> mike.tippetts@pfe-ltd.com 04/18/02 03:34AM >>>
>Hi all,
>
>I have been trying to etch Niobium using CF4 plasma but the process seems
more
>willing to strip
>the photoresist before it etches into the metal. Does CF4 have problems
with
>selectivity or is there
>another recipe for this process that could be used.
>
>Mike


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