Zeiss SIGMA Series, Instruction Manual

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ZEISS 5 Commissioning and First Operating Steps | 5.5 Modifying Gun Parameters
Analytic Gun Mode Analytic gun mode is suitable for higher probe currents. Overall, the probe current in Analytic gun
mode is about twice the probe current in Normal gun mode.
Info
After switching the gun mode, you can immediately work with the selected gun mode. For ap-
plications, which require a high probe current stability, wait 24 hours until a stability of 0.2 %/
h is reached. It is recommended not to change the gun mode during quantitative specimen
analysis.
Procedure 1. In the SEM Controls panel, select the Gun tab.
2. To switch to Imaging mode, click Imaging .
3. To return to Analytic mode, click Analytic .
5.5.2 Measuring the Probe Current
The probe current is the current that flows through the specimen. It corresponds to the total
number of electrons that hit the specimen.
Measuring the probe current using the Faraday cup ensures that the current displayed in the soft-
ware equals the incident probe current. The Faraday cup consists of a strongly absorbing material
with a cavity covered by a small aperture. If the beam is focused in this cavity, no secondary elec-
trons and no backscattered electrons leave the Faraday cup.
Parts and Tools
Designation Part no.
Faraday cup 348342-8055-000
Procedure 1. Load the Faraday cup into the specimen chamber. Refer to Loading the Specimen Chamber
[
}
85] .
2. Evacuate the specimen chamber.
3. Switch on the gun. Refer to
Switching on the Gun [
}
90] .
4. Switch on the EHT. Refer to Switching on the EHT [
}
90] .
5. Set a magnification that allows transmission of the complete electron beam into the cavity
of the Faraday cup through the aperture of the Faraday cup.
6. From the Panel Configuration Bar , select Specimen Current Monitor .
à The Specimen Current Monitor window is displayed.
7. Activate the SCM On checkbox.
8. Activate the Spot checkbox.
à
Green crosshairs are displayed on the image. The crosshairs indicate the position of the
beam spot.
9. Grab the crosshairs and move them into the hole of the Faraday cup.
à
The probe current is measured continuously.
à The measured probe current is displayed in the Specimen I readout.
Instruction Manual ZEISS SIGMA series | en-US | Rev. 7 | 352102-9344-006 97