Are you sure you have a turbo on your system?  1mT base pressure
sounds more like a roughing pump.

Whether you need a turbo depends on how precise you want your etching
system to be. There are a lot of older plasma etchers out there with
just a wet or dry roughing pump. Make sure your pump oil is compatible
with the gases you are using.

I've been running fluorine plasmas (including SF6) in my chamber for
the past 6 years without any trouble. It has an Alcatel turbo pump
which has a special seal that prevents corrosive gases coming in
contact with the bearings.



On Thu, Jan 13, 2011 at 10:58 PM, zhanggeng  wrote:
>  Hi all,
>
>     We are using a RIE machine(Model:PX-1000, March company) for SiNx dry
etching (SF6+O2). The vaccum is achieved by a turbopump (Base presure of ~1
mTorr). The problem is that the turbopump is easily destroyed by the residual
materials produced during the etching process.
>
> Here are our questions:
>
>     1) whether the turbopump is not so suitable for this dry etching process,
or any special turbopump should be used here.
>     2) Can we use a oil pump to replace the turbopump? any filter (what kind?)
should be used to avoid the impact of the residues?
>     3) whether molecular pump can be used in this vaccum system. Our oil pump
seems much weaker than the turbopump(pump speed:16.6 m3/h < 30 m3/h).and how to
set up this vaccum system?
>
> It will be very helpful and appreciated if someone can share the experience on
the vaccum system.
>
> Thank you!
>
> Geng Zhang