[labnetwork] Ion Implanter Varian 350D

[John Shott]

Bruce:

While it has been a number of years, we used to have a Varian 350D in 
which we ran phospine, arsine and boron trifluoride.  It also had a DP 
on the source that was backed by a little 5.6 CFM (as I recall) Alcatel 
mechanical pump.  To the best of my knowledge, however, I don't think 
that we ever ran Fomblin in that pump.  I think that we always ran it 
only on normal hydrocarbon "white" oil.  My recollection, however, was 
that we only changed oil in the backing pump every 4-6 months and used 
to get years of life out of it.  We used to change pump oil when that 
little pump couldn't hold the foreline pressure lower than about 30 
microns of mercury.  I may be able to dig up some old logs to confirm 
that those numbers are about right.

I also vaguely recall that we tried using Fomblin in a pump on a LPCVD 
nitride system at one point, got some sort of crystallization in that 
.... and went back to hyrdocarbon oil.  Note:  we DO use Fomblin in most 
of our pumps that are still wet pumps so I am not "anti-Fomblin" in any way.

Hopefully someone who is a bit more of a chemist than I may be able to 
comment ... but I think that it may be worth asking the question: is 
Fomblin the best fluid to use in this application.

Good luck,

John

On 6/6/2014 4:44 AM, Bruce Tolleson wrote:
>
> We have a Varian 350D Ion Implanter.  We are using Phosphine and 
> Boron-tri-fluoride in our processes with a diffusion pumped source and 
> a wet backing  pump  (Fomblin serviced).   We have noticed over the 
> years that our wet pump will only last about 4-6 months before needing 
> a rebuild.  We check pH regularly, and flush and fill when needed.  We 
> find that we have a crystallization of sorts occurring in the pump 
> that is killing the pumps.
>
> Is there anyone out there that is using this tool or this process that 
> has had or is having  this issue and has rectified it?
>
> Any suggestions are appreciated.
>
> Thank You,
>
> Bruce E. Tolleson
>
> Rochester Institute of Technology
>
> 82  Lomb Memorial Drive, Bldg 17-2627
>
> Rochester, NY 14623-5604
>
> (585) 478-3836
>
> http://www.rit.edu/~962www/logos/tiger_walking_rit_color.jpg
>
>
>
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