[labnetwork] Chamber pressure during reactive e-beam evaporation

[Dennis Culver]

Hello Aamer,
Out of curiosity, what type of high vacuum pump are you using? If you are using a cryo pump, I would be very worried about oxygen build up in the pump! Is the voltage adjustable on your E-gun power supply and how low can it be adjusted?  
The 1st thing that comes to mind is arcing at higher pressures from the HV feed thru up to the gun.  You would of course need to recenter the beam at lower voltage and you may need to run at a lower beam current......
Dennis J.  Culver  Culver Consulting
5960 Valentine RoadUnit 14, Mail box 13Ventura, CA 93003
Ph (805) 648-1184Fx (805) 648-1485
Cell(805)680-7389
dennis at culverequipment.com  


-----Original Message-----
From: Dr. Aamer Mahmood <amahmood at hbku.edu.qa>
To: labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
Sent: Thu, Feb 7, 2019 1:28 pm
Subject: [labnetwork] Chamber pressure during reactive e-beam evaporation

 Hello all,We have been doing reactive oxide depositions with e-beam evaporation of metals and a few sccm oxygen flowing through our system. We do not have a variable position gate valve and can only control the oxygen MFC settings. The corresponding chamber pressure has been less than 2e-4 Torr. I have recently received a request to deposit reactive metal oxide films at higher oxygen flow rates that'll correspond to higher chamber pressure during deposition.I am hesitant to increase the deposition chamber pressure due to the increased flow rate because the manufacturer mentioned the aforementioned chamber pressure as an acceptable upper limit for the e-gun. I'd appreciate any insights/experiences on this matter particularly 1) how does increased oxygen pressure in the chamber affect the system hardware, 2) any safety concerns etc.Thanks in advance.
-Aamer MahmoodQatar Environment and Energy Research InstituteDoha, Qatar
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