[labnetwork] Regarding : Aluminium E-Beam Evaporation

[Ryan Rivers]

The best way around the aluminum crucible shattering problem is to use a
FABMATE crucible, but also to use a carbon spacer under your liner. A 1/8"
thick carbon disk works in a pinch, you can get fancier with some machine
shop time. We use them in all our ebeam tools the Marvell NanoLab and I've
only seen a handful of crucible liners shatter from thermal load in the
last decade.

Primary cause of crucible liner breaks are incomplete thermal contact on
one side of the crucible. When you're pouring too much heat in to make up
for that contact, one side goes red hot, the other never gets there.
Thermal expansion drives the rest. The spacer prevents your liner from
cooling through the sides and only cools at the bottom. You heat with less
joules in, so less shock. Lets your entire crucible heat more evenly and
more readily stabilize through the problematic regions of melt formation.

-Ryan

On Mon, Aug 29, 2022 at 4:47 PM Michael Yakimov <yakimom at sunypoly.edu>
wrote:

> One of things which may hinder Al deposition from carbon crucible is
> Aluminum carbide formation on the surface. It will show up as yellow stuff
> on the surface after venting, eventually decomposing in the air.
> It is a part of tribal knowledge for me; I couldn't find a good reference
> in 5 minutes.  there is mention of the effect here:
> https://link.springer.com/article/10.1007/BF00792405
> <https://link.springer.com/article/10.1007/BF00792405>
> Industrial operation of vacuum aluminum evaporators made in refractory
> compound alloys - SpringerLink
> <https://link.springer.com/article/10.1007/BF00792405>
> Vaporizing elements of various types and sizes are being produced from a
> TiB2-TiC alloy in the Special Design and Technology Department of the
> Institute of Materials Science, Academy of Sciences of the Ukrainian SSR,
> and widely used in vacuum deposition plants for the application of aluminum
> coatings to glass, plastics, fabrics, paper, metals, and film and other
> coiling materials. The ...
> link.springer.com
>
>
>
> ------------------------------
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Zhichao
> Wang <zhichaow at udel.edu>
> *Sent:* Monday, August 29, 2022 12:14 PM
> *To:* Chandan H B <chandanachar95 at gmail.com>
> *Cc:* labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
> *Subject:* Re: [labnetwork] Regarding : Aluminium E-Beam Evaporation
>
> Chandan,
>
> We use a pattern beam with the pattern sweeping/rotating constantly during
> the deposition, and a fabmate crucible. The rest of the parameters are
> pretty similar. The highest deposition rate we've tried is 15 Angstrom/s.
>
> --
> Chao
>
> On Mon, Aug 29, 2022 at 8:07 AM Chandan H B <chandanachar95 at gmail.com>
> wrote:
>
> Dear Lab network community,
>
> We are currently facing an issue in the deposition of Aluminium in one of
> our Electron beam evaporation tools, we tried intermetallic, fab mate,
> copper, glassy coated graphite, and graphite crucibles for the evaporation.
> It seems that none of them are working out.
> We see crucible gets broken at the initial deposition quite often.
>
> Are we missing out on any parameters unchecked?
> Kindly recommend us a few parameters or solutions for the same.
>
> Any suggestions/Inputs are highly appreciated.
> Thanks in advance!
>
> Regards,
> CHANDAN H B
> THIN FILM ENGINEER
>
> P.S: Here are a few parameters that are provided to the tool.
> Power: 10KW
> Voltage: 10KV constant
> Current: Variable
> Rise1 & Soak1: 5min & 1min /8min & 2min
> Rise1 Power: 4% (for intermetallic crucible)
> Rise2 & Soak2: 5min & 1min /8min & 2min
> Rise2 Power: 8% (for intermetallic crucible)
> Ramp down: 5min
> Rate of deposition: 0.1nm/sec
> Beam Pattern: Spot Beam at the center of the crucible
> Crucible Volume: 20cc
> Material fill %: As recommended 67-75%
>
>
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