FEI Quanta FEG 250, User'S Operation Manual

Page: 208 / 228

System Options: Quanta Morphologi
9-60
Filter membranes
Particles on filter membranes can be observed almost directly after
sample preparation, but in the Low Vacuum mode only.
Use: all types of conductive and nonconductive particles
• pressure of 60 – 100 Pa
• accelerating voltage: >= 10 kV
• spot size: >= 3
• free working distance (FWD): 7 - 10 mm
• image resolution: >= 1024 × 884
• dwell time: >= 10 µs
Note:
Depending on the particle character, electron beam induced jumping
of particles can be observed using long dwell times. Image integration
can be applied to prevent this phenomenon, but the calculated result
will suffer by an error of app. 5 %.
Another way to prevent this phenomenon is to coat the filter with thin
conductive layer before filtration.
SYMMETRICAL LOW VACUUM DETECTOR
(SLVD)
This detector is used instead the LFD to prevent shadowing effect of
the observed particles.
Installation procedure:
1. With your glowed hand, grasp the detector by the rigid connector
end. Hold it with the detector head facing towards you, and the four
detecting electrodes facing down.
2. Insert the detector (gold fingers facing forward) into the connector
located at the back of the chamber, behind the conical lens. A
keyed connector position prevents the user from inserting the
detector upside-down.
3. Hold the detector head by its green sides (not electrodes) and
push back the head onto the Standard Insert until it stops.
4. Removing of the detector must be done in the opposite way than
installing. First, remove the detector head from the lens insert.
Second, pull the other end of the detector out from the connector.
FIGURE 9-51 SYMMETRICAL LOW VACUUM DETECTOR
SLVD INSTALLED IN THE CHAMBER