ZEISS
5 First Operating Steps | 5.1 Prerequisites for Commissioning and Operation
5 First Operating Steps
This chapter describes the switching on/off as well as the first operating steps of the Device. Fur-
ther information on operation is available in the Online Help of your software and the applicable
instruction manuals, if available.
5.1 Prerequisites for Commissioning and Operation
Read the instruction manual carefully before commissioning and keep the manual for further use.
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Basic training and safety briefing successfully completed.
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Chapter Safety read and understood.
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Familiar with general Windows
®
based programs.
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Familiar with SmartSEM.
5.2 General Guidelines for Working with Focal CC
The Focal CC minimizes charging effects of non-conducting specimens by injecting a gentle local
flow of gaseous nitrogen onto the area of interest.
The Focal CC nozzle and assembly are adjusted at the installation to be as close as possible to the
block-face specimen, ensuring optimum conditions for charge compensation.
For a given knife installation, the cutting plane and hence working distance do not vary. Once the
nozzle height is adjusted for the cutting plane, it does not need routine adjustment.
However, each time the specimen is exchanged, it is good practice to view and confirm that the
nozzle return location is optimum. Also, it is worth checking that the nozzle clamping position is
robust. For some specimens, the region of interest may be significantly smaller than the area pre-
sented by the block face. At the ideal nozzle location the nozzle points directly at the region of in-
terest, not just at the specimen block.
5.3 Vacuum Guidelines for Working with Focal CC
Do not leave the Focal CC turned on in the software such that the gas is continuously flowing
when no experiment is being performed. The nitrogen gas load places a strain on the vacuum sys-
tem, and will reduce the time period before servicing or replacement parts are required.
Do not use the Focal CC gas flow at a default value of 100 %. This places a heavier strain on the
vacuum system and will reduce the time period before expensive vacuum components need re-
placement, and may speed up degradation in column reliability. Users are encouraged to employ
the minimum gas flow required by their application in order to mitigate charging events which
can impact the interpretation of important features. The technique is not intended to provide the
same charge compensation power as working in VP mode. For example, if a gas flow can success-
ful mitigate charging events from regions of interest in an experiment where the freshly cut block
face is imaged, it is not necessary to use a higher flow rate to compensate charge in empty insu-
lating resin areas, or to compensate charge for repeated scanning events where high dose is in-
jected into small areas.
ZEISS electron optical columns are equipped with both, upper and lower ion pumps. The upper
ion pump deals with the high vacuum conditions of the FEG tip. The lower ion pump is impacted
by the relatively poor chamber vacuum when working in Focal CC mode.
After long high vacuum mode only operation (several months), if users wish to start using Focal
CC again, they must increase Focal CC pressure slowly from a low start, e.g. 10 %, to the desired
value over a minimum of one hour. This allows slow outgassing of the lower ion pump. The col-
umn separation valve must be open during this process with the HT off. Outgassing creates heat
in the ion pump and is a chain reaction. If the chain reaction is too fast and creates a suddenly
Instruction Manual ZEISS Focal CC | en-US | Rev. 2 | 349561-8021-000
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