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SEM
OPERATIONAL INSTRUCTIONS
The following are set as standard operational procedures for the
Carl Zeiss DSM 960 Scanning Electron Microscope - RSC 135.
Director: S. Benham
7378, office
7236, SEM lab
857-5827 (home)
If the microscope fails to operate for ANY reason, please
turn off the instrument, backfilling the specimen chamber with
dry nitrogen. See Step 2 below for chamber evacuation.
<<< DO NOT TOTALLY VENT THE CHAMBER
>>>
********** PLEASE **********
ONLY INSTRUCTED PERSONNEL are to use the SEM/EDS without
supervision. The list price of this equipment exceeds
$250,000.00. There are NO PLU faculty or staff authorized
to
remove any panel or service the SEM/EDS system in any way,
other
than the Director.
If something fails to operate properly, please inform the
Director
immediately.
The SEM does generate X-rays at higher accelerating voltages.
Do not tamper with the column in any way.
Unless 25 Kv or 30 Kv are required for your experiment, please
Do Not use these higher Kv accelerating voltages.
Filament
life is extended, and high-powered X-rays are reduced.
Samples are also preserved. Do not exceed 1 KV
for uncoated
samples.
If your sample disintegrates under high accelerating voltages,
the Director will instruct you in the care and cleaning
of
the microscope specimen chamber and the column.
Clear your
calendar for a full two days, and be prepared for the
intense
smell of isopropyl alcohol, because the chamber must
be
cleaned before another sample can be run.
The instrument is "fail-safe", assuming standard
operating
procedures are followed.
The SEM/EDS
room is a laboratory, Not a Bar or
Restaurant! NO FOOD
NO DRINKS
10/00 OPERATING THE ZEISS DSM 960 SEM
PLEASE WASH HANDS BEFORE YOU USE
THE SEM/EDS
1. Switch on the instrument to the
VAC setting with the KEY.
2. Vent specimen chamber:
a. turn on dry nitrogen tank primary valve.
b. turn low pressure valve CW until a reading of 10-15# (usually
pre-set) is obtained on the O-100# gauge.
c. gently push the VENT switch (red light will be on in the center
of the switch) located the front panel of the column console.
You will hear a distinct hiss.
d. turn the main valve on the N2 tank off when the sample drawer
can be opened.
3. PUT ON COTTON GLOVES FOR SAMPLE EXCHANGE
The SEM specimen chamber is a "CLEAN ROOM" environment.
No
ungloved fingers or hands are to enter the chamber or touch any
part of the stage or the unpainted surface. Specimen
stubs and samples must be properly prepared, then handled only with
gloves or tongs. Severe vacuum leaks, or long pumpdown times
result if the above precautions are not followed.
<<<<< FINGERPRINTS OUTGAS FOREVER >>>>>
ALL SPECIMENS MUST BE CLEARED WITH THE DIRECTOR BEFORE
THEY MAY BE PLACED INTO THE SEM CHAMBER. There are
many
different methods used to mount/coat samples.
ALL SPECIMENS MUST BE DRY AND PRE-EVACUATED. Hydrated
samples will explode in the chamber.
a. Handle the specimen stub with tweezers, never the fingers.
Place specimen(s) in the correct sample holder - there are
three standard holders, depending upon the height of the
sample. Gently tighten the Allen set screw that holds
each
stub in place.
b. Arrange samples so that the electron beam will not initially
fall on a sample when the microscope is fully operational.
This may be accomplished by moving the "X" or "Y"
specimen
stage control to the end of its range.
(This procedure protects the sample from being blasted apart
when the beam is initially turned on - if you forget to set
the correct HV current.)
c. Please check specimen clearances before you close the
door. The detectors cost $9,000 EACH!
Slide the drawer closed, paying particular attention to be sure
that
specimen(s) DO NOT TOUCH the final lens or any detector in the chamber.
d. Gently push on the chamber door and press the EVAC switch on
the
front panel of the column console. The red light in
the EVAC
switch will be on prior to your pushing the switch.
e. Wait for the green vacuum gauge to reach a MINIMUM READING of
10-5 before turning on the filament.
4. Turn the KEY to the ON position.
Wait for lenses in the column to clear: The two yellow lights in
the
Blue and Yellow switches in the PHOTO BOX must not be lit before
you proceed to step 5
5 Press Space Bar on the KEY PAD: A Blank Screen will appear.
6.Turning the FILAMENT ON: The filament generates the electron beam.
Set HV knob in the HIGH VOLTAGE box
5 KV for coated specimens,
1 KV for uncoated specimens
a. Switch on the Filament - FILAMENT box
a. HIGH VOLTAGE box - depress HV switch - Red light will
come on.
b. Turn on the filament
7. Set Magnification to 20 or lower (MAGNIFICATION box
(Do not leave the microscope on magnification settings of less than
100x
for long periods of time.)
Adjust specimen stage controls to locate your sample. Rotate stage
knob
"R" (rotates specimen stage) until specimen stub is in
view.
Rotate stage knob "Z" (vertical stage movement) until
specimen is in
focus. Be sure to watch the "WORKING DISTANCE" reading
in the instrument panel. The "Working Distance"
setting defaults to a reading of 26 mm when instrument is turned
on -
this is NOT and accurate indication of the sample working distance.
When
you find your sample under low magnification by adjusting the "X"
and/or
"Y" stage knob(s), raise the magnification to 100x and
focus (see "d" and "e" below) using the coarse
focus knob to focus specimen. You will now be able to determine
the correct working distance on the SEM LED panel.
BE SURE TO OBSERVE THE "WORKING DISTANCE" number on the
panel so that you
do not run the sample into the objective lens or one of the detectors.
THE BEST IMAGES ARE OBTAINED USING A SHORT WORKING DISTANCE - 6mm.
EDS,
however, is done at working distances of about 25mm. For
our purposes
please keep working
distance at 25 mm
8. RESOLUTION BOX: turn the Coarse knob to "LOW"
or "MEDIUM".
9. FOCUS BOX: Switch Coarse/Medium switch off (no light).
1st, push the "Small Window" button (center button
on the left vertical
row of buttons in the SCANNING SPEED box. This button,
and the "Slow"
button (lower right on the right vertical row of buttons, allow
you to go
from a small, easy to focus image to the full screen image.
Focus by gently turning the large knob in the FOCUS box
Fine Focus the specimen by turning on the Coarse/Medium switch (light
on).
Focus using the large knob.
Raise magnification to desired level (MAGNIFICATION box.
Magnification
may be adjusted up or down using the coarse or fine controls.
Refocus using the large Focus knob. Set the Coarse knob (MAGNIFICATON
box
to the "MED" or "HIGH" setting
Focus using the larger focusing knob until the best image is obtained.
The smaller focusing knob is useful only when magnifications are
greater
than 10,000x.
You may now push the "Slow" button on the SCANNING SPEED
box to go back to the full size image.
10. Center the Aperture: There are four apertures on the strip.
These apertures are graded in size:
1. used for EDS ONLY
2. 120u - general use
3. 100u - GENERAL USE, including
EDS
4. 70u - photo-quality work
You must refocus, reset the focus wobble, and restigmate each time
you
change the aperture setting.
11. WOBBLER: Turn on the "wobbler" by pressing the
switch in the FOCUS WOBBLE
BOX. Adjust the knob until you observe a pulsating image.
Go the "Small window" screen size and adjust each of the
two knobs on
the Column (APERTURE strip) until the image pulsates in and out
of focus,
(no lateral or vertical shift). One knob controls the "X"
direction of
movement, the other knob controls the "Y" movement direction.
Turn off the "Wobbler".
12. Stigmate the image by adjusting the "X" and "Y"
knobs in the STIGMATOR box.
Adjust each of these two knobs until you get the sharpest image.
Increase magnification; focus
13. SIGNAL box: switch to MANUAL CONTRAST and BRIGHTNESS:
Adjust brightness and contrast knobs to their best setting for what
you
are viewing.
Speed/Preset knob (SCANNING SPEED BOX) to 2 or higher to acquire
the best
image
You are now ready to store the image, or take a photograph.
14. Photograph:
Be sure the lever on the film holder is in the "L" position.
Push film all the way into holder until you hear a "click"
Pull film out until you feel resistance.
Gently push the Yellow button in the PHOTO box on the SEM
Wait for the image and text to be put on the film
Push film holder back into the film holder.
Pull film holder lever to the "P" position.
Pull film all the way out of the holder, pushing the lever back
to the "L"
position when you feel a distinct resistance.
Wait one minute before peeling off the backing, exposing your picture.
TO
TURN OFF THE SEM:
Turn off the filament
Turn off the high voltage
Turn key to the VAC setting.
Leave at this position unless you want to
remove your sample. You are finished. Turn out the lights
and leave.
To remove sample from chamber:
Open dry nitrogen tank valve
Push the "VENT"
button on the chamber console. You will hear a distinct
hiss, then a "clunk" when the N2 gas has filled
the chamber. Pull
on the door until it opens.
Turn N2 valve off.
Remove sample.
Close door, and then push the "EVAC"
button on the chamber console.
You may now leave the room after you turn out the lights.
10/16/02
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