SIMS Sample Preparation
Surface: All samples must be polished --
in general the surface should have a <1 micron surface roughness. Furthermore,
any sample which is not intrinsically an electrical conductor must be coated
with a conductive film prior to analysis. Unless working with a special
application, we deposit a high-purity,~100 nm thick gold film on the cleaned
sample surface.
Sample Size: The Cameca ims-series Ion Microprobes
accept two types of samples: (1) thin samples which can be spring loaded
into a masked sample holder and (2) circular thick samples which must have
an OD of 1 inch and which are locked into the holder using small set screws.
Thin samples must be at least 6 mm x 6 mm but are also limited to no larger
than the 1 inch diameter of the sample holder; they should be no more than
3 mm in thickness; the back side of the sample should be flat and parallel
to the polished front side on which the analysis is to be performed. For
thick samples, we recommend using a 1 inch OD aluminum ring within which
the sample is cast in high vacuum compatible epoxy (we use Buehler
No. 20-8130-032 cold-set epoxy resin and No. 20-8132-008 epoxy hardener).
The surface roughness of the area being analyzed should be less than 1
µm -- rougher sample may be analyzed, but the data quality can be
degraded by having a poorly prepared surface.
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Grain Mounts and
1" Diameter
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Polished Thin Sections
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Left side shows <250 µm crystals embedded in epoxy which is cast
within an aluminum ring with a 1 inch outside diameter. The sample has
been polished and gold coated.
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Right side show the Cameca 1 inch diameter stainless steel sample holder.
The polished sample is placed in the holder from the backside and is then
locked into the holder using set-screws located at the upper corners of
the sample holder.
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Mounting Semi-Conductors
or Other Small, Polished Samples
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Upper Left: small piece of coated silicon wafer
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(maximum allowable size 2 x 2 cm)
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(Minimum allowable size 7 x 7 mm)
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Lower Left: tantalum mask which has a set screw for loading the Al plug
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Lower Right: aluminum plug and small spring for backloading the Ta mask
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Upper Right: Cameca 1 inch diameter stainless steel sample holder into
which the loaded mask is placed
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Scale at bottom is in centimeters
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The surface of the sample must be clean. Those materials which are not
intrinsically clean as the result of their manufacture are ultrasoniced
for ~5 minutes in ethanol and then dried in an oven at ~80 Celsius. We
coat samples which are non-conducting with a thin, high purity gold film
prior to analysis. If placing a gold film on the sample is surface is not
acceptable then we can arrange for a carbon film to be used instead.
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