SPI SEM Calibrated Mounts
Instructions For Using SPI SEM Calibrated Mounts
Introduction:
The SPI SEM calibrated mounts are made from a silicon single crystal chip. The orthogonal patterns of
0.l X 0.l mm size are composed of a series of l0um squares, manufactured by interferometer controlled
electron beam lithography. These periodic structures have an accuracy of approximately 0.2um and
an angular precision of approximately 5 arc seconds. Deviations from these measurements following
SEM examination are then indicative of the imaging properties of the SEM being tested.
The l0um periodicity of the mounted chip is a reliable length reference. Since the magnification in the
x and y direction of the SEM can vary, a check of both is required. Independent checks should also be made at the various magnifications, beam voltages and working distances to be used.
Use as a Calibrated Mount
Small particulate specimens may be dispersed onto the silicon surface, and while being photographed
in the SEM, enough of the calibrated pattern ends up in the field to document the exact magnification
of the image.
Other methods of use are possible. One can, for example, apply a portion of a membrane filter
to the calibrated mount, and the entire specimen (filter and calibrated mount) is placed in an
SPI #11005 Plasma Prep II plasma etcher (or comparable plasma etcher) and etched with oxygen in an oxygen plasma.
The polymer membrane filter is etched away, leaving trapped particulates exactly as they
were distributed on the filler, but now on the grid of the calibrated mount, especially
useful for asbestos fiber counting.
This product is also useful for characterizing quantitatively the distribution of inorganics in fibers,
papers, films and (detached) polymer coatings.
How to Handle the SEM Test Standard:
The Test Standard is made of a silicon single crystal at
100-orientation. It is highly conductive and will not be damaged by the electron beam.
To avoid warping and shattering, do not apply mechanical forces to the silicon chip. It is best to keep
it attached to the specimen stub at a few points along the periphery. In the event it is necessary,
the crystal can be removed for cleaning purposes. One has to be very careful to not break the crystal when
it is being removed. The best way is to soak the mount and crystal in
acetone for 24 hours in order to aid in the loosening of the chip from the
substrate. Then (and being sure to wear safety glasses) and with a GEM®
Scientific Razor Blade, slowly wedge the blade into the interface between
the chip and substrate. You do not want to apply too much bending stress or
the blade will break and/or the chip will break. But through acetone soaks
and this slow approach to lift-off, the chip usually can be removed.
Note: We can not overstress the need for wearing eye protection when
doing this and we can not guaranteed that the chip will not break even when
following these instructions.
The chip should be reattached using SPI #5009 Super Glue or SPI #5067
Conductive Silver Epoxy.
We recommend the following two cleaning methods with silicon chip removed from SEM mount:
1) Normal surface deposit without electron beam contamination:
Ultrasonic treatment in hot acetone followed by hot chloroform-. and gently blowing dry.
2) To remove electron beam contamination:
20 minutes treatment in highly concentrated hot sulfuric acid, followed by rinsing in distilled water,
then gently blowing dry.
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Friday July 25, 2008
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