[labnetwork] Sputtering GeSbTe

[Kevin Owen]

Iulian,

We just went through some testing with GeTe in our sputter tool at the
LNF.  Tellurium is known to be toxic, so we wanted to see how much was
released when the chamber was vented to perform a target change.  We took
samples of the breathing air near the chamber and near the operator's head
and swabs of the chamber walls before and after wiping them down with IPA.
On the chamber walls initially, we found low levels of Te, but after wiping
them down, it was below the detection limit.  All breathing air samples
came back negative for Te.  These tests were taken with the assistance of
UM OSEH, so we're confident in the results.  I can't help you with recipe
parameters, but I've copied our sputtering guy who might be able to help
(and could comment more on the tests, since he's the one who performed
them).

In a related question, now that we can successfully deposit GeTe, users at
the LNF now want to etch it, too.  If we had an ion mill, I would be OK
with it based on the same logic as above.  However, all of our plasma
etching systems run either F or Cl based chemistries and Te forms compounds
with both of these that are much more toxic than in its elemental form (20
ppb REL for TeF6).  We're concerned that even running an Ar only etch, the
Te would be embedded in the walls and then could react during a subsequent
F etch by another user.  Does anyone have any thoughts or experience with
etching Te, or even Se, based compounds?  Maybe we're thinking way too hard
about this and exposure levels are actually so minimal that it doesn't
matter?

Cheers,
Kevin

On Thu, Dec 3, 2015 at 9:49 AM, Iulian Codreanu <codreanu at udel.edu> wrote:

> Hello Everyone,
>
> I have received a request for using GeSbTe in the sputtering system. I am
> not familiar with the material and any input is much appreciated:
> -What potential contamination and/or toxicity issues should I consider and
> what mitigation strategies do you recommend?
> -Assuming this material can be used in the system, would you recommend a
> starting recipe?
>
> Thank you very much,
>
> Iulian
>
> --
> iulian Codreanu, Ph.D.
> Director of Operations, UD NanoFab
> 163 ISE Lab
> 221 Academy Street
> Newark, DE 19716
> 302-831-2784
> http://udnf.udel.edu
>
>
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-- 
Kevin Owen
Senior Engineer in Research
Operations Group, Lurie Nanofabrication Facility
University of Michigan
(734) 545-4014
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