Jim,
A couple of things you may want to look at, since I don't know what Temescal
system you are using some of these ideas may or may not apply. Most of my
experience with Temescals are the BJD-1800 or FC series and depositing Al.
Whenever we got spitting metal here is what we looked at.
Is the beam scanning across the melt?
Is the beam centered on the melt?
What does the power do while you are depositing? Does it bounce a lot or is it
stable?
In older Temescal models it is suggested that you don't use a graphite crucible
but place the melt directly in the pocket for good thermal conduction. You
should oxidize the pocket with H2O2 before placing the melt in the pocket. To
do this, pull the pocket out and pour the H2O2 directly in the pocket. Let sit
for a couple of hours to build up a nice oxide and reinstall the pocket.
Check the water cooling to make sure it is sufficient, should have a flow switch
but some maintenance people like to jumper these out.
When starting a new melt start by doing a preliminary melt. Pull melt out of
pocket and turn on side and remelt. You can do this several times to get a melt
which makes good contact with the pocket on all sides.
Hope this helps.
-Dave Marx
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Jim Beall
Sent: Friday, September 03, 2004 1:40 PM
To: General MEMS discussion
Subject: [mems-talk] prevention of spitting when evaporating Au-Cu
Greetings -
I am e-beam evaporating Au-Cu (30-70) after melting Au and Cu slugs
together in a graphite crucible. It's a standard Temescal gun, pressure
is <2 x 10-6 T and rate is 1-2 nm/sec.
I get a nice smooth, 1 micron thick film except the surface is covered
with many .25-.5 micron bumps spaced about 25 microns apart. I can see
small particles flying off the melted slug as I evaporate, even at low
rate. We routinely evaporate similar films of pure Au and pure Cu with
no problem.
Any suggestions?
thanks very much,
-Jim Beall
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