[labnetwork] ALD vacuum pump oil

[Paolini, Steven]

Mike,
  You will almost always get oil migration (backstreaming) in any vacuum chamber that pumps in the molecular flow regime for a period of time. Why do you use that oil? Is it inert? Do you run pure O2 at any time? I would recommend Fomblin 25/6 for a low V.P. and O2 safety. Alcatel 2063's are a very robust rotary pump and I have used them in the harshest of processes but to minimize backstreaming, it would be in your best interest to reduce the amount of time that you are pumping on the chamber without a gas flow (if possible), Lengthen the pumping line (if this does not create conductance problems), and use a molecular sieve trap just above the pump (Lesker, MDC, Etc.) These are the standard techniques for containing oil molecules within the pump on an application that has just a roughing pump. This problem rarely exists when the pump is used to back a turbo since the oil can't backstream through the turbo's foreline and into the throat of the pump.
Hope this helps,
  Steve Paolini
  Equipment dood
Harvard University Center for Nanoscale Systems

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Michael Call
Sent: Wednesday, October 23, 2013 3:14 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] ALD vacuum pump oil

We have a thermal ALD system that has an Alcatel 2063C2 pump with Anderol 555(A155) oil for fluid(no turbo).  We recently cleaned the system and noticed oil in the low points in the chamber. Has anyone else had any experience with this oil?  The vapor pressure for the oil is 10^-3 mBar at 100C which is fairly high.

--
Mike Call
Research Engineer
UMaine LASST
207-581-3382
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