I would think that the turbo pump would have to be specially designed (and
constructed of certain materials) to be compatible with reactive ion etching
products.  In your case the SF6 may be reacting with residual water vapor in
the chamber and creating sulfuric acid, which could damage your turbo pump.
 As Javier mentioned, you could bypass the turbo pump while the plasma is on
and evacuate the etch products with a rotary pump (filled with an
appropriate oil like Fomblin, etc.).  You might also need to pump the
chamber down for a longer time after loading your sample to more thoroughly
remove any residual water.  I know that for the RIE machines in our clean
room, any processes involving chlorine-containing gases require a 20-minute
pumpdown to remove water from the chamber and reduce HCl formation.

I hope this helps.

Brian C. Stahl
Graduate Student Researcher
UCSB Materials Research Laboratory
brian.stahl@gmail.com / bstahl@mrl.ucsb.edu
Cell: (805) 748-5839
Office: MRL 3117A


On Fri, Jan 14, 2011 at 11:05 AM, Javier Sesé  wrote:

> Are you using the turbopump during the RIE process?
> I normally use the primary pump (rotary) to evacuate the RIE etching
> products, with a by pass in the turbopump.