[labnetwork] CoFeB sputtering

[Matt Moneck]

Hi Nava,
 
We have done a lot of CoFeB (20-30% B by weight and many variations of Co and Fe percentage) in our facility, and in general, it is not a cause for concern in regards to contamination.  We have, however, had issues with flakes building up on the system shields for thick films.  
 
On the process side, there are some issues to consider depending on the application.  As Su Gupta pointed out, you need to ensure you have enough pass through flux to sustain a DC plasma.  Depending on how your cathode is set up, you may need to consider thin targets (<0.1”) if you do not have enough pass through flux.  You also need to consider substrate heat.  Boron will diffuse out of the CoFeB at temperatures of 250C or above.  Even at temperatures below 250C, you can see an impact on the coercivity.  While it is unlikely that you will approach anything near 250C from DC sputtering alone, you will want to consider temperature impacts on the film properties.  Lastly, you may want to consider the addition of an in situ magnetic field at the substrate if a strong easy axis is required.  
 
If your application is simply to have a low coercivity film, you should be able to get what you need relatively easily.  However, if your application is for other applications, such as magnetic tunnel junctions, there are many other process related things to consider.  I’d be happy to discuss more if needed.  
 
Best Regards,
 
Matt
 
-- 
Matthew T. Moneck, Ph.D.
Executive Manager, Carnegie Mellon Nanofabrication Facility
Electrical and Computer Engineering | Carnegie Mellon University
5000 Forbes Ave., Pittsburgh, PA 15213-3890
T: 412.268.5430
F: 412.268.3497
 <http://www.ece.cmu.edu> www.ece.cmu.edu
nanofab.ece.cmu.edu
 
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Nava Ariel-Sternberg
Sent: Tuesday, March 28, 2017 8:37 AM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] CoFeB sputtering
 
Good morning,
 
Does anyone have experience with sputtering CoFeB? Are there any issues to worry about? (tool contamination, process sensitivities, etc.)
 
Thanks,
Nava
 
 
Nava Ariel-Sternberg, Ph.D.
Director of CNI Shared Facilities
Columbia University
530 w120th st., NY 10027
Room 1015/MC 8903
Office: 212-854-9927
Cell: 201-562-7600
 
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