[labnetwork] Gold e-beam deposition - carbon contamination

[Nadia Pervez]

Hi Youry,

We also have this problem in our load locked system, also using fabmate
with a spacer. We've been wiping down the liner, gold slug from the
crucible, and tweezers used to handle the pellets with IPA at each crystal
change and refill. We also changed all the shields and shutters (etc).
While the situation has improved I still see evidence of spitting.
Deposition rates are set at 1 and 2 A/s, I'm not sure if it is happening
with both, as you can imagine the powers are pretty close. I have not tried
rinsing the pellets with IPA, or not using the slug we already have.

Meanwhile, our user who was most adversely affected by this is able to get
Au depositions without spitting in a filthy open chamber tool by
evaporating at 0.1A/s.

Nadia


On Fri, Jan 31, 2025, 2:45 PM Youry Borisenkov <yb2471 at columbia.edu> wrote:

> 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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