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ZEISS 5 First Operating Steps | 5.7 Working with Specific Specimen Types
5.7 Working with Specific Specimen Types
The following general factors need to be considered during any kind of specimen preparation:
§ You may need to reduce the size and weight of the specimen to fit it on the holder and to
ease specimen manipulation for observation.
§
Mineral and metallurgical specimens may require polishing. Etching and electro polishing may
also be required.
§
The specimen should be able to withstand the vacuum of the microscope as it might become
damaged or deformed.
§
If you want to use the specimen in High Vacuum (HV) mode, it needs to be clean and dry. The
presence of dust, moisture, oils, and grease can lead to charging, contamination, and longer
pump down times. Otherwise use VP or EP vacuum mode.
§
Porous specimens take a long time to pump out in High Vacuum mode.
§ The specimen should be firmly attached to the specimen stub or holder either mechanically or
by gluing. Silver dag and carbon dag can be used as conductive glues for small specimens.
Carbon tabs/tape are also convenient but may not provide good mechanical stability.
§
Health and safety procedures regarding the handling of the specimen during its preparation
need to be observed.
§
There should be good electrical connection between the surface of the specimen and speci-
men stub, especially for non-conductors.
Specimens can be divided into three main categories:
§
Conductive Specimen [
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§
Non-conductive Specimen [
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§
Hydrated Specimen [
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5.7.1 Conductive Specimen
Conductive specimens (conductors) can be easily observed in a “conventional” SEM.
Conductive specimens are imaged in High Vacuum (HV) mode. For HV mode, only use the 20 μm
or 30 μm mid-column apertures.
Recommended
Parameters
The following parameters are recommended for conductive specimens. The values given are only
suggestions. The operator may find that different values give better information for the types of
specimens that are being investigated.
Parameter General Mi-
croscopy EDS High Resolution
EHT 20 kV
§
20 kV for metals
and minerals
§
8 kV to 10 kV
for semiconduc-
tors and organic
materials
30 kV
I Probe 200 pA 1000 pA or adjust
for 30 % deadtime 10 pA
WD 8.5 mm 8.5 mm for a 35°
take off (elevation)
angle 5 mm
Filament § Long Fil. Life
activated
§ Fil I set to first
peak for qualita-
tive analysis
§ Long Fil. Life
deactivated
Instruction Manual ZEISS EVO | en-US | Rev. 10 | 354706-0780-006 91