New procedures using copper liners for Innotec Users coming soon
nperez at stanford.edu
Tue Mar 30 13:58:46 PDT 2010
Please read all new changes coming to Innotec and Innotec Users.
You may have seen Jim and Jeannie testing a new hearth with copper
crucibles. They are working to solve the problems of the sources
blowing up, being contaminated and the growth of residuals on the sides
and bottom of the sources. The feeling is the loss of good thermal
contact between the source and hearth is the root cause of the source
failures. A common industry approach is to place the materials in
crucibles instead of our approach where we remove and replace the source
in the hearth with each use. Source suppliers have tables showing what
type of crucible is recommended for each material. Jim and Jeannie
have tried a number of these combinations without any success. Instead
of a source failure we were observing crucible failures.
The concept of dedicating materials to its own crucible still makes a
lot of sense. This would prevent the degradation of the sources. Jim
came up with the idea of making the crucibles out of copper and
machining the hearth to have a good fit and hence thermal contact to the
hearth. This is the configuration Jim and Jeannie have been testing.
There goal is to release this to the lab member community.
So far the testing has been going very well. No offset between the
crystal monitor and the deposited thickness has been observed. This
means if you continue to target 100nm on the crystal monitor you will
get the same thickness on your sample.
One item which has been noted during the testing is the thermal transfer
is much better with the new copper crucibles. The source is cooled
better which means you will need a little higher power than in the
past. Again, the crystal monitor will still tell you the correct
deposition rate and film thickness. On side effect of the higher power
better cooling is a tendency to create a dimple at the beam location.
To prevent drilling a deep hole in the source, the new recommended
approach is to us the sweep function. This will change your power
settings, but the crystal monitor will give you the correct deposition
rate and film thickness.
In summary these changes are being made to prolong the life of our
sources, minimize contamination and prevent the explosion of sources all
which result in a cost saving of materials. This cost savings is not
trivial as the cost of a new Pt starter source has crossed the $7,000
line and gold is not far behind.
Once the conversion has taken place, please take the time to work with
Jeannie on getting retrained on the new operating specifications.
_*Any questions or concerns, please contact staff; Jeannie Perez,
Maurice Stevens, Jim Haydon, Ed Myers or Mary Tang.
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