Operating Procedures: Specimen Preparation and Handling
5-2
User Manual
C O N F I D E N T I A L –
limited rights
Feb 2018
Revision A
Specimen Preparation and Handling
The sample material must be able to withstand a high vacuum environment without outgassing. It must be clean
and conductive. Oil, dust, or other materials may cause sample charging or contaminate the chamber, which could
hinder or even prevent evacuation.
Note
Always wear lint- / powder-free clean room gloves when handling anything inside the specimen chamber to minimize oils,
dust, or other contaminant pollution of the chamber environment.
Needed Items
•
Class 100 clean-room gloves
•
Specimen stubs and conductive adhesive material
•
Tweezers
•
1.5 mm hex wrench
•
Prepared sample
Natural Specimen
If no coating is desired, the Low Vacuum mode can be used to stabilize the specimen for observation. This mode is
useful if there is a suspicion that a coating might alter the specimen.
Coated Specimen
If the specimen is nonconductive (plastic, fiber, polymer or other substance with an electrical resistance greater
than 10
10
ohms), the specimen can be coated with a thin conductive layer. This conductive layer reduces beam stir
due to sample charging and improves imaging quality.
For successful imaging, rough surfaced specimens must be evenly coated from every direction. Biological, cloth and
powder specimens may require carbon or other conductive painting on portions of the specimen that are hard to
coat.
Coating makes the imaging sharper and reduces beam penetration. It may mask elements of interest for X-ray
analysis (thus the use of carbon for geological and biological specimens).
For more information on specific preparation techniques, see
Scanning Electron Microscopy and X-Ray Microanalysis
,
3rd ed., by Joseph Goldstein et al., Springer, 2003.
Mounting Specimen on Holder
Wafers and PGA devices have individual sample-mounting procedures. If you are using a wafer piece or other
sample, attach the specimen to the specimen holder using any suitable SEM vacuum-quality adhesive, preferably
carbon or silver paint. The specimen must be electrically grounded to the sample holder to minimize specimen
charging. If you are using another method to mount a specimen, make sure the specimen is conductively attached
to the holder.
Note
The sample holder is not directly grounded to the chamber ground because it is connected to the BNC feed, allowing
measurement of the specimen current.
C a u t i o n !
Store samples and sample holders in a dry nitrogen storage cabinet. Dust on samples can get drawn into the electron
column, degrading performance and requiring an Thermo Scientific Customer Service call to correct the problem.
