[labnetwork] Disposal of used silicon wafers

[Demis D. John]

We send batches of ≥200 wafers (100mm) to
https://nanosiliconinc.com/
Michelle Piffero <michelle at nanosiliconinc.com>

Our interns generate a *lot* of "DepCal" wafers from our internal
calibration processes (see here
<https://wiki.nanofab.ucsb.edu/wiki/Process_Group_-_Process_Control_Data#Deposition,_Dielectric_(Process_Control_Data)>)
with various dielectrics on them. NanoSi worked with us to make sure
Reclaimed wf. specs were good enough for our needs, and cost was lower than
brand new wf's.
Quality has varied within batches, which has been a bit of an issue, but we
can use all wafers for at least one calibration process regardless of
quality (particle count is our main bifurcation spec).

-- Demis (contact info <https://wiki.nanotech.ucsb.edu/wiki/Demis_D._John>)
*Reminder*: The NanoFab has a publications policy
<https://wiki.nanotech.ucsb.edu/wiki/Frequently_Asked_Questions#Publications_acknowledging_the_Nanofab>


On Mon, Nov 17, 2025 at 1:47 PM Yakimov, Michael <myakimov at albany.edu>
wrote:

> As a wild guess… Once you have any metal deposition on any of those wafers
> – they cannot really be re-melted as semiconductor-grade silicon.
> Repolishing may be OK, although I suspect final cleaning would still be
> pricy if anything like Fe, Au or Cu was there.   Maybe they can be used as
> ferrosilicon for steel alloying, if anyone would bother with that for a
> $2/kg commodity.
>
> I was told that locally taped cardboard boxes with sharp objects, like
> broken glass or Silicon, can be disposed as regular landfill trash – as
> long as nothing falls out easily. (your local regulations may vary)
>
>
>
> Thanks
>
>
>
> Mike
>
>
>
> _______________________________________________
>
> Michael Yakimov
>
> Research scientist
>
> Department  of Nanoscale Science and Engineering
>
> University at Albany - State University of NY
>
>
>
> 253 Fuller rd.
>
> Albany NY 12203
>
>
>
> Phone: 518-437-8609 lab
>
> e-mail: myakimov at albany.edu
>
>
>
>
>
>
>
>
>
>
>
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> * On Behalf Of *
> vsoares at inesc-mn.pt
> *Sent:* Friday, November 14, 2025 8:58
> *To:* 'Lab Network' <labnetwork at mtl.mit.edu>
> *Subject:* [labnetwork] Disposal of used silicon wafers
>
>
>
> Dear all,
>
>
>
> We are a small lab and through the years have accumulated hundreds of used
> silicon wafers and would like to dispose of them.
>
> I considered having them recycled but we would need a thousand minimum.
> The ideal for us would be to send them to a company that can remelt the
> silicon into ingots, but I only found a company in the US and we are in
> Europe.
>
> Also, there are not many semiconductor labs in Portugal so I am having
> trouble finding options.
>
> What do you do with your used wafers?
>
>
>
> Thank you in advance,
>
>
>
> Virginia Soares
>
>
>
> Melhores Cumprimentos/ Best Regards
>
>
>
> Virginia Soares
>
>
>
> INESC-MN
>
> Rua Alves Redol,9
>
> 1000-029 LISBON
>
> PORTUGAL
>
> Tel: +3513100237
>
> https://inesc-mn.pt
>
>
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