[labnetwork] Advice on mitigating spitting during indium thermal evaporation

[Carlos Gramajo]

Hi Joseph,

I am not familiar with depositing In, but I might suggest using one of
those boats that have a cover with a small hole on the top. This might help
in keeping some undesired splatter, at the very least away from the rest of
your chamber. For other materials that tend to splatter a slower ramp and
multiple soaks can help liberate gases that are trapped  and tend to have
violent ebullition. That might be another thing to try.

Cheers,

Carlos

On Wed, Apr 15, 2026 at 12:06 PM Joseph E. Palmer <
jpalmer at exchange.princeton.edu> wrote:

> Hello all,
>
> I’m reaching out for advice on mitigating spitting during thermal
> evaporation of indium.
>
> We are evaporating In from a resistively heated crucible setup (Mo
> crucible with a surrounding resistive heater), targeting deposition
> rates of ~30 Å/s for bump-bonding applications. Our typical run pressure
> is ~1×10⁻⁵ Torr.
>
> We perform a pre-melt with a slow ramp, but are still seeing
> intermittent spitting during deposition, leading to particulates and
> film defects.
>
> At this point, I’m trying to better understand the dominant mechanism
> (e.g., oxide skin rupture, trapped gas, or localized overheating) and
> what process changes are most effective in suppressing it.
>
> If anyone has experience with indium evaporation and would be willing to
> share insights or discuss offline, I would greatly appreciate it.
>
> Thank you in advance,
>
> --
> Joseph E. Palmer
> Chief of Operations for the MNFC
> PMI, Princeton University
> Contact:
> Office: 609-258-4706
> Cell: 609-731-8962
>
>
>
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-- 
Carlos Gramajo
Cleanroom Research Scientist
Shared Equipment Authority (SEA), Rice University
Cell: 713-470-8115; Office: 713-348-8243; cg70 at rice.edu
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