Differences

This shows you the differences between two versions of the page.

--- jeol_820_sem [2004/12/11 21:28] – external edit 127.0.0.1
+++ jeol_820_sem [2008/05/29 15:59] (current) – verstoep
@@ Line 18: / Line 18: @@
 If you use a tilt sample holder you can use silverpaint to mount the sample. Use this sample holder only if the use has been demonstrated to you since it is //very easy// to damage the final lens with it (repair cost: >10000 Euro)!
 ===== SEM =====
@@ Line 24: / Line 27: @@
 {{images:emission.png}}
-  - Mount the sample holder on the transfer stick.
+  * Loading the sample
-  - Place the transferstick in front of the loadlock with the excentric hole //down//
+    - Wear powder free gloves.
-  - Push the red button. The loadlock will be evacuated
+    - Mount the sample holder on the transfer stick (Don't use glue or paste).
-  - While the loadlock pumps down, start Elphy Quantum and log in
+    - Place the transferstick in front of the loadlock with the excentric hole //down//
-  - Drive the stage to the exchange position with the ''stage control'' window. **Never push the ''init'' switch on the console**
+    - Push the red button. The loadlock will be evacuated
-  - While the loadlock pumps down and the stage drives to the exchange position, turn the WD to the ''4x4'' marker and while doing that, feel good about the fact that now you are doing at least 3 things at the same time!
+    - While the loadlock pumps down, start Elphy Quantum and log in
-   - When the red light is off, open the loadlock valve by //carefully// rotating it a quarter turn anti-clockwise, pulling it towards you and rotating it a quarter turn clockwise (so that it is locked and doesn't get sucked in by the vacuum. Get help if this goes even slightly heavy or if the pressure goes up (scale light of current meter goes out)
+    - Drive the stage to the exchange position with the ''stage control'' window. **Never push the ''init'' switch on the console**
-  - Carefully slide the sampleholder onto the stage. **DO NOT USE FORCE, this is a delicate, micrometer accurate stage!**
+    - While the loadlock pumps down and the stage drives to the exchange position, turn the WD (Working Distance) to the ''4x4'' marker and while doing that, feel good about the fact that now you are doing at least 3 things at the same time!
-  - Unscrew the transferstick //carefully// and pull it back until it clicks
+     - When the red light is off, open the loadlock valve by //carefully// rotating it a quarter turn anti-clockwise, pulling it towards you and rotating it a quarter turn clockwise (so that it is locked and doesn't get sucked in by the vacuum. Get help if this goes even slightly heavy or if the pressure goes up (scale light of current meter goes out)
-  - //carefully// turn the valve a quarter turn anti-clockwise, let it slide in and turn a quarter turn clockwise.
+    - Carefully slide the sampleholder onto the stage. **DO NOT USE FORCE, this is a delicate, micrometer accurate stage!**
-  - Push the red button to vent the loadlock //while holding the transferstick so that it doesn't fall on the floor// (if you think it is rediculous that I write this you should now admire the cracks in the metal-doped, X-ray blocking glass)
+    - Unscrew the transferstick //carefully// and pull it back until it clicks
-  - If the transfer did not go very smooth or the pressure went up, put vacuum grease (next to the transfer stick) onto the transfer stick and slide it back and forth (you are still wearing gloves, so your hands will not get dirty)
+    - //carefully// turn the valve a quarter turn anti-clockwise, let it slide in and turn a quarter turn clockwise.
-  - Put the transfer stick in the holder
+    - Push the red button to vent the loadlock //while holding the transferstick so that it doesn't fall on the floor// (if you think it is rediculous that I write this you should now admire the cracks in the metal-doped, X-ray blocking glass)
-  - Turn the WD to the desired value (be very careful not too set it too far up, what 'too far' is depends on the sample holder; ask help if unsure
+    - If the transfer did not go very smooth or the pressure went up (strangely this is indicated by having no illumination of the current meter and you can't turn on main power), put vacuum grease (next to the transfer stick) onto the transfer stick and slide it back and forth (you are still wearing gloves, so your hands will not get dirty)
-  - Drive the stage to the chessy
+    - Put the transfer stick in the holder
-  - Turn the monitor contrast and brightness to 2 o' clock
+  * Activate the System
-  - PCD ''off'' (button out)
+    - Turn the WD to the desired value (be very careful not too set it too far up, what 'too far' is depends on the sample holder; ask help if unsure
-  - Mode ''SEM''
+    - Drive the stage to the chessy
-  - Blanker ''off''
+    - Turn the monitor contrast and brightness to 2 o' clock
-  - SEI detector ''on'', select ''SEI'' detector
+    - PCD ''off'' (button out)
-  - Scan speed ''tv scan''
+    - Mode ''SEM''
-  - Check that filament heating current setpoint = 0
+    - Blanker ''off''
-  - Check that HV setpoint is 20 kV (or lower)
+    - SEI detector ''on'', select ''SEI'' detector
-  - Switch on HV (red switch)
+    - Scan speed ''tv scan''
-  - Switch current meter to 1 nA full scale
+    - Check that filament heating current setpoint = 0
-  - Slowly turn filament heating current to the indicated value (at the 'shoulder', see plot. do not exceed 2.6A. Ask if unsure)
+    - Check that HV setpoint is 20 kV (or lower)
-  - You should now measure a current on the sample
+    - Switch on HV (red switch)
-  - Adjust contrast and brightness
+    - Switch current meter to 1 nA full scale
-  - You should now see the chessy
+    - Slowly turn filament heating current to the indicated value (at the 'shoulder', **see plot**. do not exceed 2.6A. Ask if unsure)
+    - You should now measure a current on the sample
+    - Adjust contrast and brightness
+    - You should now see the chessy
@@ Line 58: / Line 64: @@
 You can navigate with the joystick and set 1 of the 4 moving rates. (Be careful not to push ''init''!)
-== Imaging ==
+== Imaging (astigmatism) ==
 Correction of astigmatism is most conveniently done on the chessy. Then you can move to the sample, if it is as thick as the chessy there should hardly be any astigmatism on the sample and you only need to adjust the focus a little bit. Taking a picture can be done in Elphy Quantum by clicking ''file'' -> ''new image'' and setting the slowscan options to the desired value. Then set ''slow 2'', ''EBPG'', and blanker ''External''. Click the scan icon and you take a photo!. To get the micron bars right, see 'write field calibration' in the [[electron beam lithography]] manual.
@@ Line 65: / Line 71: @@
 Increasing the acceleration voltage improves the performance of the electron-optical lens column so the spot gets smaller.  High-energy electrons also penetrate deeper into the material (the effect of that depends on what you want to see, your sample and the detector you are using).
-Theoretically there is an optimum in the WD because of (among others) competing effects between spherical and chromatic abberations of the lenses. In practice with the 820 to go to really high magnifications you have to be simply at high kV and small WD (//minimumL 8 mm!!!)
+Theoretically there is an optimum in the WD because of (among others) competing effects between spherical and chromatic abberations of the lenses. In practice with the 820 to go to really high magnifications you have to be simply at high kV and small WD (//minimumL 8 mm!!!//)
-To correct astigmatism turn the focus knob back and forth, if you see horizontal and vertical (or: these rotated over some angle) lines get out of focus at different points you have to adjust the stigmator. Set focus in the middle between where the hirizontal and vertical features are sharp. Optimize X and Y astigmatism. Optimize focus. Repeat until no further improvement is seen.
+To correct astigmatism turn the focus knob back and forth, if you see horizontal and vertical (or: these rotated over some angle) lines get out of focus at different points you have to adjust the stigmator. Set focus in the middle between where the horizontal and vertical features are sharp. Optimize X and Y astigmatism. Optimize focus. Repeat until no further improvement is seen.
-Changing the aperture.\\
+== Changing the aperture ==
 For currents below 100 pA, use the smallest aperture; between 100 pA and 5 nA use the second smallest and above 5 nA (hardly used) use the third smallest aperture. After changing the aperture, check the alignment by pushing the wobbler button and adjusting the X and Y position of the aperture until the center of the image remains fixed (also at large magnification and max amplitude of the wobbler). Then switch off the wobbler.
-=== Shut down ===
+=== Shutting down ===
   - PCD on (button in)
   - Turn back the filament heating current //slowly// to avoid breaking it