[labnetwork] Blistering of metal film stack on PMMA
Mark K Mondol
mondol at mit.edu
Fri Feb 1 17:16:12 EST 2019
Mary, Norman and Nathan all have good points. Here are my two paise's
worth of advice:
It would be nice to have the substrate farther away from the source. It
would also be nice to have a second shutter (close to the substrate and
not blocking the deposition sensor) so the substrate is not getting
heated during the warming of the source. You probably don't have the
ability to change those things though.
Norman is correct that a magnet can deflect stray electrons and might be
the solution for you.
In the NanoStructures Lab we don't use crucibles except for Cu and SiOx,
thereby eliminating Carbon contamination.
Anecdotally, it seems that some evaporators generate enough Xrays to
expose PMMA and some don't, well the Xrays are probably generated but
aren't emitted in a direction that exposes PMMA. Any wavelength shorter
than 220nm will expose PMMA, we use an old UV aligner to flood expose
PMMA for a variety of processes.
I guess I would try to see if it is heat that is the problem by
evaporating 10nm of Au to find out if it works with shorter
evaporations. If heating is the problem see the two solutions at the
top, or try to install a cooler behind your substrate. You might also
find an evaporation recipe that uses a shorter or less powerful soak
step to reduce heat. Possibly a different position on your holder might
help, but anything that is not directly above the source will make for
more difficult liftoff.
Regards,
Mark K Mondol
--
Mark K Mondol
Assistant Director NanoStructures Laboratory
And
Facility Manager
Scanning Electron Beam Lithography Facility
Bldg 36 Room 229
www.rle.mit.edu/sebl
mondol at mit.edu
office - 617-253-9617
cell - 617-224-8756
More information about the labnetwork
mailing list