[labnetwork] [EXTERNAL] Gold e-beam deposition - carbon contamination

[Matthew Moneck]

Hi Youry,

We had issues with carbon contamination years ago, and we switched to a
tungsten crucible.  We have not had any issues since we made the switch
(note the chamber was cleaned as well).

Best Regards,

Matt

On Sat, Feb 1, 2025 at 11:54 AM Demis D. John <demis at ucsb.edu> wrote:

> Adding a tantalum pellet to the Au source will getter the carbon and
> reduce spitting.
>
> I can’t quite find the original paper, but here are some web pages that
> reference it:
> 1)
>
> https://compoundsemiconductor.net/article/116629/Tackling_the_foot#:~:text=concern.-,The%20combination%20of%20the%20crucible%20liner%20and%20tantalum%20%E2%80%98getters%E2%80%99%20looks%20like%20a%20win%2Dwin:%20the%20deposition%20rate%20increases%20while%20reducing%20gold%20spitting.,-But
>
> 2)
>
> https://www.memsnet.org/memstalk/16896/#:~:text=look%20for%20a%20paperwritten%20in%20the%201970s%20that%20suggests%20adding%20a%20small%20piece%20of%20tantalum%20to%20yourgold.%20%20The%20Ta%20will%20not%20melt%20but%20it%20will%20control%20the%20spitting.
>
>
> I don’t have measurements of carbon contamination with this - although we
> do this in our e-beam evaporators.
>
> -- 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 Sat, Feb 1, 2025 at 05:17 Czwakiel, James <czwakj at rpi.edu> wrote:
>
>> Youry
>>
>> Once contamination is detected…. Clean clean clean
>> All metal covers removed and blasted and ultra sonically cleaned
>> Plus …. Make sure crucibles are not touched even with gloved hands…..
>> always use tweezers
>>
>> James Czwakiel
>>
>> Semiconductor Equipment Engineer
>>
>> [image: Image]
>>
>>
>>
>> Get Outlook for iOS <https://aka.ms/o0ukef>
>> ------------------------------
>> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Youry
>> Borisenkov <yb2471 at columbia.edu>
>> *Sent:* Friday, January 31, 2025 11:59:09 AM
>> *To:* Fab Network <labnetwork at mtl.mit.edu>
>> *Subject:* [EXTERNAL][labnetwork] Gold e-beam deposition - carbon
>> contamination
>>
>>
>> *CAUTION:* This email originated from outside of the organization. Do
>> not click links or open attachments unless you recognize the sender and
>> know the content is safe.
>> Hi All and happy Friday,
>> I know it is a topic that has been discussed multiple times, however, I'm
>> still lacking a solution that works and will appreciate you sharing your
>> experience.
>>
>> Currently we are using a Fabmate crucible, and getting some carbon
>> contamination .
>> For clean Gold layers we use thermal evaporation. The films are good but
>> it requires a lot of gold.
>>
>> So far we tried using a Molybdenum crucible with and without a spacer.
>> The issue with this approach was that eventually after some time, we get
>> carbon contamination back. I believe it's present in the chamber and
>> eventually a critical mass is built on top of the gold in the crucible,
>> coming from the chamber.
>>
>> Were anyone successful in overcoming carbon contamination in their e-beam
>> deposition overtime?
>> What are the procedures you are following? Maybe cleaning more frequently?
>>
>> --
>> Thank you,
>> Youry Borisenkov
>> CNI <https://cni.columbia.edu/columbia-university-clean-room>
>> Columbia University
>> CEPSR 1017, New York, NY, 10027, United States.
>> <https://sustainable.columbia.edu/crown-commuter>
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-- 

--
Matthew T. Moneck, Ph.D
Executive Director, Claire & John Bertucci Nanotechnology Laboratory
Electrical & Computer Engineering | Carnegie Mellon University
5000 Forbes Avenue, Pittsburgh, PA 15213-3890
Phone: 412-268-5430
ece.cmu.edu
nanofab.ece.cmu.edu
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