[labnetwork] Experience with CdS and dry etching

[Brent Gila]

Hello Mark,

Here is the link to the CDC website with Cd exposure limits.
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.atsdr.cdc.gov_csem_csem.asp-3Fcsem-3D6-26po-3D7&d=DwIDaQ&c=pZJPUDQ3SB9JplYbifm4nt2lEVG5pWx2KikqINpWlZM&r=EhqHy4a2rnA5a4ehzWAAfKveFS3lPv3RmQTaTocONM4&m=paqIUb_Y4G_a57SmOlow7d6JiqnQeZVGGx4IN4jjaUU&s=mh1sb9grYAXTukWGeEaK6dkF-3wXmmXVgVFYweJO2mE&e= 

Since you mentioned toxicity, I assume you are not worried about process 
cross contamination and more concerned with the tool operator/service 
engineer.  This is less of a concern if the tool is loadlocked compared 
to a non loadlocked etch system.  I would estimate the amount of 
material etched during the process would leave a very small amount of Cd 
solids in the etch tool so the exposure level would be minimum.  I spent 
many years doing ZnCdSe epi growth and we wore respirators during 
chamber cleans/maintenance and kept the area around the tool very 
clean.  After a service and cleanup, we never had elevated Cd levels in 
the swipes that were tested.

Your waste from the tool (gloves, wipes, chamber cleaning debris, sleeve 
guards) will all now have trace Cd and the EPA allows up to 1.0ppm of Cd 
in the waste stream.  So to be safe, all the waste should be bagged up 
and labeled accordingly, Cd is a RCRA metal. Only Hg has a lower 
allowable limit of 0.2ppm, so Cd is one of the more restricted RCRA 
metals to have to deal with.

Unfortunately I have no CdS etch experience to further comment.

Best Regards,
Brent

-- 
Brent P. Gila, PhD.
Director, Nanoscale Research Facility
1041 Center Drive
University of Florida
Gainesville, Florida 32611
Tel:352-273-2245
Fax:352-846-2877
email:bgila at ufl.edu



On 10/24/2017 9:54 AM, Mark Morgan wrote:
> Greetings all,
>
> we have a user that’s interested in putting CdS in our etchers and i 
> am loath to allow it due to its toxicity but i thought i’d poll the 
> group and hear what others have done.
>
> Any have experience with dry etching of this material? or experience 
> with this material as part of a process within your etchers but not 
> the primary etch target?
>
> Thank you so much for your comments and input.
>
> best regards
>
>
> Mark D. Morgan
> Research Engineer, Washington Nanofabrication Facility (WNF)
> National Nanotechnology Coordinated Infrastructure (NNCI)
> University of Washington
> Fluke Hall 132, Box 352143
> (206) 221-6349
> mmorgan3 at uw.edu <mailto:mmorgan3 at uw.edu>
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.wnf.washington.edu_&d=DwIDaQ&c=pZJPUDQ3SB9JplYbifm4nt2lEVG5pWx2KikqINpWlZM&r=EhqHy4a2rnA5a4ehzWAAfKveFS3lPv3RmQTaTocONM4&m=paqIUb_Y4G_a57SmOlow7d6JiqnQeZVGGx4IN4jjaUU&s=efcbuO4whndOxt30zMcxXSs5gJ4bE5eeBafH1GIGnLE&e=  
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