5 Commissioning and First Operating Steps | 5.8 Working with Variable Pressure
ZEISS
Parameter
Ideal
Ultimate
Limits
Pressure
60 Pa – 80 Pa
5 Pa – 500 Pa
Trade off between
skirt effect and
charge compensa-
tion
Beamsleeve bias
350 V
0 V – 400 V
Discharges
Acquisition condi-
tions
Drift compensated
frame average
All
Specimen details
may move due to
charge buildup
Detectors
InLens (best image resolution)
150 Pa max, no to-
pography
EsB (discrimination of charge buildup)
Max. grid voltage
1000 V
500 Pa, topography
Efficiency of diode
detectors decrease
with lower accelerat-
ing voltage (70 % at
1 kV)
Field of view
350 µm or 800 µm for wide field lens
700 µm or 1600 µm for Nano-twin lens
Depending on beam-
sleeve aperture used
and lens configura-
tion
EDX
WD 10–12 mm; 350 µm beamsleeve aperture
5.8.2.4 Changing to Nano VP or XVP Mode
NOTICE
Touch alarm is not available
In Nano VP mode touch alarm is only available when beamsleeve bias voltage reaches approxi-
mately 200 V. In XVP mode touch alarm is not available.
4
Avoid a Beam Gas Path Length (BGPL) of less than 1 mm.
4
Watch the moving stage in TV mode.
4
To stop the moving stage immediately, press
F12
or press the
Break
push button of the
dual joystick panel.
Info
A higher pressure can be set within a few seconds. Achieving a lower pressure may require
some more time, because the specimen chamber has to be evacuated by the pre-vacuum
pump.
Procedure
1. In the GeminiSEM Control panel, select the
Control
tab.
2. In the
Variable Pressure
section, click
Nano VP
or
XVP
to start the pre-defined macro.
The macro automatically performs the following actions:
à
If EHT is on, it is turned off.
à
The column chamber valve is closed.
110
Instruction Manual ZEISS GeminiSEM series | en-US | Rev. 2 | 349500-8138-000