[labnetwork] E-Beam Evaporation, Ni optimization.

[Nathan Nelson - Fitzpatrick]

Hi Chandrashekar,

We had an issue like this about 18 months ago when evaporating Ni in "Fabmate" graphite crucible liners.  Our crucible liners would only last about 4 or 5 depositions before being hopelessly cracked and the Nickel melt would degrade from its normal shiny lustre to a dull grey colour.  We did not experience spitting, but otherwise our experience sounds similar.

We ended up purchasing a Tungsten crucible liner for our Ni evaporation.  The liner has been working for the past 18 months through many Ni depositions and only has one hairline crack.  In migrating to the W liner our deposition power has gone down (for the same deposition rate) and we now see much less blistering of resist materials when performing a lift-off (this used to be a significant problem in our E-beam evaporator).

Best regards,
  -Nathan
--
Nathan Nelson-Fitzpatrick  PhD
Nanofabrication Process Engineer
Quantum NanoFab
University of Waterloo
200 University Avenue West
Waterloo, ON   Canada  N2L 3G1
Ph: +1 519-888-4567 ext. 31796





From: Chandrashekar S Kambar <kambar009 at gmail.com<mailto:kambar009 at gmail.com>>
Date: Wednesday, 31 July, 2013 8:13 AM
To: "labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>" <labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>>
Subject: [labnetwork] E-Beam Evaporation, Ni optimization.


Hi,

We are trying to optimize Ni with E-Beam Evaporator (TECPORT).

The E-Beam power is raised in two steps: RAISE 1, SOAK 1 AND RAISE 2, SOAK 2.
ELECTRON BEAM PATTERN: Focused to one point (to the middle of the crucible).
CRUCIBLE: Graphite.

ISSUE: During the RAISE 1, everything seems to be normal and only the material in the middle of the crucible gets melted. During the RAISE 2 the material starts to spit out of the crucible. During the deposition the spitting increases drastically, thus we will be forced to stop the deposition. After the deposition when we take out the crucible, crucible was broken across the wall. However there was no damage done to the pocket holder (Hearth).

Power % : Raise 1: 5% (V= 6.99 KV and I ~ 70 mA)
                Raise 2: 10% (V= 6.99 KV and I ~ 120 mA)
                During the deposition Power % goes up to 16% and the current goes up to 180 mA ( V = 6.99 KV constant).

We need to know, if there is any way to reduce the crucible cracking and to avoid the spitting of the material.

QUESTION 2:

During the deposition the crucibles are cracked and its pieces are stuck with the Ni material. Is there any way to recover the material by removing the graphite pieces?

Thanks and Regards,
Chandrashekar S Kambar.


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