[labnetwork] E-Beam Evaporation, Ni optimization.

[Mark Heiden]

Hi Chandrashekar, At first it seems that your raise #2 power is just too
high but many other factors may be in play. Hopefully your system has a
sweep controller which you should be using to set the Electron Beam Pattern
to sweep the surface of the melt. This is the best way to distribute the
heat across the entire melt. Focusing the beam in one stationary spot in the
center will cause exactly the problems that you are describing and could
lead to a damaged liner or hearth. If you have no sweep available, you may
try extending your rise times to more slowly heat the material. Any time
that you heat too fast or have to shut off the beam instantly (like when the
melt is spitting all over) you run the risk of cracking the liner from
thermal shock. 

 

Also, you should run the system manually first and watch carefully what
happens and at what power levels. If your shutter does not have a chimney or
hole that allows the rate sensor to see the melt at all times, you will need
to do the testing with the shutter open and record what power levels it
takes to achieve a given deposition rate. This way you can set the rise and
soak programs to safe levels and when your shutter opens it will already be
at the desired deposition rate.  

 

If the crucible liner disintegrates and leaves pieces in the melt, we
replace the liner and the melt since it is likely contaminated and nickel is
one of the cheaper materials to purchase.

 

Hope this helps,

 

 

Mark Heiden 
UC Riverside 
Center for Nanoscale Science and Engineering 
NanoFab Cleanroom Manager 
(951) 827-2551 
mheiden at engr.ucr.edu 

 

 

 

 

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu]
On Behalf Of Chandrashekar S Kambar
Sent: Wednesday, July 31, 2013 5:13 AM
To: 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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