jwc at snf.stanford.edu
Tue Aug 10 19:12:06 PDT 2004
Charis and others:
RE: Questions 1 and 2 sound like charging or artifacts of sample surface
charging. You can see charging on your samples on the picoammeter as
changes to Specimen Current over a short time frame say ~ ten seconds.
CARBON DOTS -- NOT:
I would not recommend placing carbon dots into the raith system. This
will result in so much out gassing as to negatively impact the
cleanliness of the chamber and column upon said out gassing event. If
you must secure your samples and are not using the clips on the sample
holder I would recommend using very small pieces of the thin
spectrographic grade carbon dots from ted pella.com.
WARM UP TIME to Stability:
Do allow enough time for the system to reach thermal equilibrium (~50
minutes) I have found that in one hour it meets the beam drift
specification of < 10 nm per minute of dot shot time. I do this check
every time I qualify the system.
BE CLEAN AND ALWAYS Bake your samples:
It is important that everyone strives to maintain a clean UHV
environment in the chamber. This means gloves always, solvent clean and
bake all apparatus or holders that are placed into the chamber every
time. Every sample must be soft baked either oven or hot plate temp >
150 degrees Celsius. I recommend 170 degree C. for 90 second on the hot
plate or 2 hours in the Blue M oven.
It is strongly recommended for samples after exposure/ development to
bake at 90 C for 2 min. them load ASAP. We have a hot plate that is
always on in the Ebeam Lab for your usage. Please be sure to return
this hot plate to 130 degrees Celsius after doing your bakes for the
RE: 3: Focus drift ?!! I am not sure how or why the focus could be
drifting. I have not observed this in my recent runs.
This would be a huge problem and I am sure everyone would be having
poor writes if this is the case. I will check it out the next time I am
on the system.
Follow the Step by Step Procedures: Follow closely the procedures I
have laid out and you should get consistent results each and every time
on the RAITH system. If you are not getting the results you desire ten
please set up a daytime session to work together with me so we can
resolve your issues of concern.
Thank you for your inputs!
Charis Quay Huei Li wrote:
>(1) beam drift/settling right after beam is unblanked, same as has been
>seen before. several hundred nm.
>(2) stigmation varies from place to place on sample by several %.
>(3) focus also drifts over time.
>problem (3) could be due to the fact that i'm using carbon dots but i've
>never seen (2) when i'm not near a clip. what was the problem the last
>time we saw (1)?
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