ZEISS
5 Description | 5.1 Cryo Trap
5 Description
5.1 Cryo Trap
Purpose
For SEM imaging, especially for low kV imaging, hydrocarbon contamination is very critical as it
massively influences image quality. The Cryo Trap is used to minimize contamination in the speci-
men chamber caused by volatile hydrocarbon compounds.
Position
The Cryo Trap is a purely mechanical device that is attached to the EDS3 port of the GeminiSEM
chamber. The Cryo Trap assembly includes a dewar vessel mounted outside, an adapter flange
connecting it to the specimen chamber, a thermoconducting rod plus a metal plate reaching near
the electron beam.
6
4
2
3
1
5
Fig. 1: Cryo Trap assembly
1
Blind Flange (currently not used)
2
Lid (with borehole)
3
Dewar
4
Adapter Flange
5
Cooling Plate
6
Cooling Rod
Function
The chamber vacuum provides the thermal isolation of a dewar vessel, which is filled with liquid
nitrogen. The extreme cold will be transferred into the specimen chamber by a copper rod that is
attached to the dewar bottom. A metal plate is attached to the tip of this copper rod. This metal
plate is cooled down to -170°C. It acts as a trap for hydrocarbon contamination. Hydrocarbon
compounds stick to the cold surface and are thus prevented from depositing on the specimen sur-
face whilst the system remains cold.
LN
2
continuously evaporates and leaves the dewar through the bore hole of the lid as gaseous ni-
trogen.
There is no electronics and software integrated to the Cryo Trap. There is no measurement of the
final temperature, and there is no monitoring of the filling level of LN
2
in the dewar.
Instruction Manual ZEISS Cryo Trap | en-US | Rev. 2 | 346000-8166-000
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Summary of Contents for Cryo Trap
Page 1: ...Instruction Manual ZEISS Cryo Trap...
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