[labnetwork] Regarding : Aluminium E-Beam Evaporation

Tue Aug 30 16:09:40 EDT 2022

Hello,

We struggled for a while getting Al to work well in e-beam evaporator. It works very well with a slow heat and cool using a tungsten crucible liner. The Al doesn’t wet over the liner, and the liner doesn’t crack. You can still burn through it with the e-beam if you aren’t paying attention to fill level though.

Thank You,
JOE MADUZIA
Senior Research Engineer, Grainger College of Engineering, MechSE, Univ of IL
2239 LuMEB | (P) 217.244.6302 | https://cleanroom.mechse.illinois.edu/

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Ted Wangensteen
Sent: Tuesday, August 30, 2022 8:05 AM
To: Ryan Rivers <rrivers at berkeley.edu>
Cc: labnetwork at mtl.mit.edu; Michael Yakimov <yakimom at sunypoly.edu>
Subject: Re: [labnetwork] Regarding : Aluminium E-Beam Evaporation

Ryan has hit on the key thermal explanation, and the best way to help this is the Carbon spacer he mentioned.
We used this on Lesker tools.
Kurt Lesker sells the spacer, but I'm not sure what tool you are using.

-Ted Wangensteen

On Tue, Aug 30, 2022 at 8:07 AM Ryan Rivers <rrivers at berkeley.edu<mailto:rrivers at berkeley.edu>> wrote:
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<mailto: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://urldefense.com/v3/__https:/link.springer.com/article/10.1007/BF00792405__;!!DZ3fjg!7hVfwponNLyYKEezPAlGKgy9Tu-xxv3gBvLweMk84xrZZZaBFF9vmU6cU1X-c16GGqTt-p3DMqVT_z3_IuTBZVz_8A$>
[https://media.springernature.com/w200/springer-static/cover/journal/11106.jpg]<https://urldefense.com/v3/__https:/link.springer.com/article/10.1007/BF00792405__;!!DZ3fjg!7hVfwponNLyYKEezPAlGKgy9Tu-xxv3gBvLweMk84xrZZZaBFF9vmU6cU1X-c16GGqTt-p3DMqVT_z3_IuTBZVz_8A$>
Industrial operation of vacuum aluminum evaporators made in refractory compound alloys - SpringerLink<https://urldefense.com/v3/__https:/link.springer.com/article/10.1007/BF00792405__;!!DZ3fjg!7hVfwponNLyYKEezPAlGKgy9Tu-xxv3gBvLweMk84xrZZZaBFF9vmU6cU1X-c16GGqTt-p3DMqVT_z3_IuTBZVz_8A$>
Vaporizing elements of various types and sizes are being produced from a TiB2-TiC alloy in the Special Design and Technology Department of the Institute of Materials Science, Academy of Sciences of the Ukrainian SSR, and widely used in vacuum deposition plants for the application of aluminum coatings to glass, plastics, fabrics, paper, metals, and film and other coiling materials. The ...
link.springer.com<https://urldefense.com/v3/__http:/link.springer.com__;!!DZ3fjg!7hVfwponNLyYKEezPAlGKgy9Tu-xxv3gBvLweMk84xrZZZaBFF9vmU6cU1X-c16GGqTt-p3DMqVT_z3_IuSfkL7DsA$>

________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> on behalf of Zhichao Wang <zhichaow at udel.edu<mailto:zhichaow at udel.edu>>
Sent: Monday, August 29, 2022 12:14 PM
To: Chandan H B <chandanachar95 at gmail.com<mailto:chandanachar95 at gmail.com>>
Cc: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu> <labnetwork at mtl.mit.edu<mailto: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<mailto: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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