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3.1 Preliminary Operation
3.1.1 Check of Column Vacuum
At the beginning of SEM operation, check the evacuation control
panel. The following conditions must be met:
(1) Lamps of IP1, IP2 and IP3 RESET switches are lit.
(2) Ion pump readings are better than the followings.
IP1: 2 × 10
-7
Pa
IP2: 2 × 10
-6
Pa
IP3: 5 × 10
-5
Pa
(Pressing MODE switch on the Evacuation control panel shifts
forward the blinking of status display lamps. Read vacuum when
each of IP1 to IP3 lamp is blinking)
If vacuum readings do not satisfy the above conditions, gun
baking is required. Refer to “Maintenance” in section 4.
(3) EVAC POWER switch is set at 1 (ON).
(4) TMP POW ON, NORMAL lamps and the lamp of SC EVAC
switch are lit.
(5) Vacuum of S.C (specimen chamber) is better than 2x10-3 Pa.
(Read vacuum when S.C lamp is blinking)
(6) APT HEAT switch is set at AUTO.
Usually keep the APT HEAT switch on the evacuation control
panel at AUTO.
If the objective lens aperture is contaminated, charging will
degrade image quality and the image will drift because of micro
discharge. Such problems are noticeable at low accelerating
voltages. The aperture is heated to about 150ºC to remove contaminants to one tenth or less
of what it would be at room temperature.
The aperture heating will be turned OFF automatically when you press S.C AIR switch to
introduce air into the specimen chamber. The 30 minutes wait will be placed automatically
before introducing air when S.C AIR is started while APT HEAT switch is ON. The aperture
heating will start again when the specimen chamber vacuum recovered by S.C EVAC
operation. Note that after the aperture heating turned ON, image drift may be observed for
about half an hour.