Prepared on April 22, 2007
JEOL 2010F - STEM Alignment
I. Pre-alignment conditions:
1. Perform standard upper column alignment. The specimen must be at eucentric position.
2. Insert and center the 150um C2 aperture (Largest)
3. Remove the Obj. aperture if it is in.
II. Align Mode:
Press the STEM button on Knob Pad ONCE. This initiates the ASID align mode. Scan
coils are not active. The following conditions are now automatically set in align mode.
CBD 1.9nm-9, 40kx magnification.
1. Lower magnification if you can not see any beam. Center beam by Shift X and Y. Set
the Objective Focus (R1) step size to 3, increase OL by 3 clicks (DV= +12), Focus probe
with C2 lens (Brightness), center spot with Bright Shifts (Shift X and Y).
2. Decrease the OL 6 clicks (DV= -12) Adjust C2 lens (Brightness) clockwise until a
caustic image is just observed. Center the caustic spot with Bright Tilts.
3. Repeat steps 1 & 2 several times. Set OL to DV = 0.
4. Optional: Align Gun Tilt (DEF) using anode wobble at CBD 1.9nm-9 mode.
5. Optional: Align Gun Shift using Bright Tilts at smallest spot size and gun
shift at largest spot size.
6. Optional: Return to CBD 1.9-9 mode and repeat from step one above.
III. Setting the desired probe conditions
Now Press the STEM button on Knob Pad a SECOND time
1. Go to FasTEM Client menuSelector, in the middle of the menu, choose Probe
Condition, set to Degauss first then to the operating probe condition. You may choose
spot#7 for most applications.
Choose the beam current and probe size needed as shown in the table. Smallest
(low current) spots use DV= -16 and CL Aperture #3, High current probes use
DV= 0 and CL aperture #2. However, continue using Aperture #1 for alignment.
2. Stop the scan by pressing SPOT button (one of scan mode buttons) on the ASID
(above R1) (Mag should be XXXX on small green screen, if not continue pressing
SPOT). A convergent beam diffraction pattern can be seen on the florescent screen.
3. Go to FasTEM Client menuSelector,
Spot size
DV
C2 Aperture
Choose the 15cm DFI camera length
3
6
75 um (#2)
from the drop down list, and roughly
4
6
75 um (#2)
center the BF disk in the screen center
using the Bright Shifts (not Tilts).
5
6
75 um (#2)
4. a) Choose TV-align 15cm from the
6
6
75 um (#2)
camera length drop down list; b) On Gatan
7
-16
30 um (#3)
TV-Bot Camera, Turn Intensifier Fully
8
-16
30 um (#3)
Counter-Clockwise; 3) Raise viewing
9
-16
30 um (#3)
screen (R1) 3) Turn Intensifier just slightly
10
-16
30 um (#3)
clockwise until you see the BF disk on the
monitor. Be very careful that you do not damage the camera.
Prepared on April 22, 2007
5. Roughly center beam on monitor using projector shifts (R2). Obtain a shadow image
of your sample (Ronchigram). You may have to lower the objective focus by several
DV values to get a low magnification shadow image. Center an amorphous part of the
sample in the center of the BF disk. Return to DV value for the chosen probe condition.
5. Adjust Z-height to obtain Gaussian focus. As the Gaussian focus is approached, the
shadow image magnification will become large at the optic axis (looks like a fish eye).
The magnification will change with angle in such a way that the shadow image is
circularly symmetric. In this case the coma-free axis can be located accurately. It is
easier to see at the low current conditions. At higher currents, make sure the video
image is not saturated.
6. Carefully Center the coma-free axis in the Ronchigram at the screen center with the
Projector Shifts (R2)
7. Press the Condenser Wobble button (R2). Set the AMP and FREQ to #2 settings (R2).
If there is a misalignment of the beam between the Condenser and objective lenses, the
Ronchigram features will translate during the condenser wobble. Use the Bright Shifts
(not Bright Tilts) to center the image wobble about the coma-free axis. The pattern
should oscillate in and out on the coma-free axis.
Optional: This is normally very close and you may skip this step for most
applications. Press the HT Wobble button and use the BRIGHT TILT control to
center the image wobble about the coma-free axis. This is difficult to adjust. It may
be better to start with a lower magnification (out of focus) Ronchigram and slowly
work towards Gaussian focus while correcting.
8. Adjust CL stigmators (L1) if infinite magnification portion of the shadow image is
not symmetric Move to an amorphous specimen area if possible. At underfocus the
characteristic ring of infinite azimuthal magnification can be seen. This should already
be circular but can be adjusted using the CONDENSER STIGMATOR (if using the
small phosphor screen, the correct shape is slightly elliptical). Use the focus knob to
pass the shadow image through focus to see the effect of astigmatism. Carefully comafree axis to the center of monitor (the spot mark) using Projector Shifts (R2).
9. Optional: If you plan to use the EDS system, you will need to use the Hard Xray Aperture (HXA - second from top). Now is a good time to insert and center
the aperture about the coma-free axis. It is difficult to position HXA. First try
inserting the aperture and then wiggle the insertion knob gently to find the
aperture. If you cannot find the hole, try removing the C2 aperture (infinite
position). Another option is to use the side-to-side motion to find one side of the
HXA then turn the knob back ¾ of a turn. Use the in/out drive to find the hole.
Center the HXA about the coma-free axis. At the lower STEM magnifications,
you will see some vignetting caused by the HXA in the STEM image. Do not
collect EDS spectra from these regions.
Prepared on April 22, 2007
10. Choose correct C2 aperture. (See the table above). It is difficult to find #3 (30 um) C2
aperture. The right way to insert it is: a) first turn selector knob to #3; b) then adjust the
front knob (in/out drive) counter-clockwise. Carefully Position the correct C2
aperture on the coma-free axis.
11. Choose the operating camera length from the drop down list. Choose 12cm, 15cm or
30cm for JEOL ADF STEM detector. For EELS, (skip step12) choose 3cm or 4cm and
use TEI DF Detector. For bright field STEM, use 15cm, 30cm or 60cm and BF TEI
detector, or use high contract objective aperture to isolate the center of the BF disk.
12. If you intend to do STM-EELS, go to optional directly. a) Insert the JEOL ADF
detector (the one above screen) and b) center the coma-free axis in the center of the
detector using Projector Shifts (R2). If you can not see the edge of the detector, you
may have to move sample around to a thicker region; c) Press EXT (JEOL ADF) on the
upper left corner of ASID;
Optional: For STM-EELS, choose camera length 3cm or 4cm and use TEI DF
Detector (below monitor). In the Filter Control Menu, Select “TV Camera In”.
You should see a CBED pattern on TV monitor. Center the BF spot to the center
of monitor using Projector Shifts (R2). Take out “TV Camera In”. Choose “TEI”
on the ASID (the upper left corner button of ASID).
13) To obtain a scan image: a) Press PIC (scan mode) and set the
Scan Speed to the “2” mode; b) Verify FasTEM client says
“PIC” and NOT “RDC” for the image mode; c) In the
DigiScan window, click Search. You should now have an
image on the computer monitor. If you don’t, check: EXT or
TEI detector is selected, ADF detector brightness and contrast
are correct (Use the assistance of Waveform monitor (check it
on DigiScan window) to obtain right brightness and contrast),
there is a sample and it is not too far out of focus. When
recording, make sure ASID is NOT in SR
mode or in sub-area PIC mode. In both cases
the magnification will not be correct. If you see
scan lines in your recording image, go to the
tool icon on the DigiScan window and unselect
the “line Sync”.
If the image quality starts to degrade - it
may be contaminating. A beam shower
can be done by removing the C2 aperture,
spread the illumination by changing the
objective focus. Use shadow image to observe illuminated area.
14) To finish, a) press TEM button on the knob pad (between R1 and R2); b) take out
JEOL ADF detector (pull out first then rotate (count-clockwise)); c) take TEI detector
by pressing “Retracted”; d) Change C2 aperture into #1 and center it. e) Close the scan
window.