raith issues?

James Conway 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. 

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 
UVN-30 people.

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!

James Conway

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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