Tool bar and button bar (Many SEM functions are mouse-controlled)

To insert your sample Check that high voltage (HV) is off (no yellow background) Click on Vent Insert sample. Wear gloves or use tools. Check sample height with “elephant nose”. Bottom of nose is where highest point on sample should be. Click on quadrant showing CCD image (typically lower right) Make sure image is live, not paused! (No double green bars in upper right corner.) Slowly close door while watching monitor to assure that sample/holder is clear of pole piece and detector Click on “Pump” with left hand while holding door shut with right hand. Check that door is shut! Push top of door against chamber.

Before pumpdown: get oriented With the door open –Move the stage to be under the beam: X=0, y=0 “Control zero” is also supposed to work Enter positive and negative values for x and y Observe and record the direction the stage moves Perform a similar operation after you get an image to correlate directions on screen to directions on the sample

Magnetic hazards Ferromagnetic particles are potentially the most dangerous thing you can image If they get sucked into the column, the rebuild will cost $60-100k! Trying to image loose ferromagnetic particles in immersion mode will be fatal!!! They can be imaged in EDX mode They can be imaged in immersion mode if firmly embedded in plastic. Do not use tape!!

Secondary Electron Detector Backscattered Electron Detector Fractured Aluminum

Getting started toward an image When adequate vacuum has been reached, chamber icon becomes green and HV button changes from grey to black. Click on HV!

Get an image! Black screen: –Check that H(igh) V(oltage) is on: yellow background? HV automatically shuts off when switching between High Vac and Low Vac! –Turn on waveform feature Increase contrast and brightness so waveform fills region between lines –Go to minimum magnification Can you see the aperture? If not, you are in big trouble. Check HV! Try spot size = 4, 15 kV

Link Initially your stage should be about 13 mm down if you have not raised it to the 10 mm mark..but could be anywhere: it has no way of knowing where you mounted the top of your sample! Focus Increase magnification Focus Link Z-coordinate is now correct Less crucial if using only samples of minimal thickness Absolutely crucial for samples of widely varying thickness Extremely crucial if sample is taller than elephant nose!

Image optimization With Everhart-Thornley or Low Vac Detector, raise stage to about 5 mm –Typically during pump-down with roller ball –With cursor low on screen, press roller ball and roll mouse up –Watch active (not paused!) image of sample mount on CCD –Translation speed is proportional to distance cursor is from starting point

Increase magnification Re-adjust focus Repeat process At about 5kX, link Raise sample to 5 mm Switch to TLD (Through Lens Detector) Re-focus Go to immersion mode Optimize image

More stuff on the NovaNano The generic working distance is 5 mm. (It was 10 mm on the Quanta) –ETD –TLD (SE and BSE, “field-free” and “immersion” modes) –LVD –Also the eucentric working distance –Focus to about 5000X, then Link. Do this early in the process. Do it repeatedly…especially if using the Helix detector

Furthermore If you are using the 2-sample holder, the pins are 16 mm apart If you are using the 8-sample holder, the pins are 19 mm apart. –Always make a drawing of the locations of your samples on the holder –Be extremely careful of orientation: get the sides of the holder on the translation axes –Remember that the CCD camera is mounted in the rear of the chamber

Further still more You can move the stage in the x- and y- directions by typing coordinates into the boxes in the “Navigation” page You can also move the stage from the image (not CCD) by holding down the roller ball and moving the mouse –The arrow points in the direction you want to look –The arrow points in the direction opposite to the one in which the stage moves

Still further more yet If you move the stage by typing a value into the box on the “Navigation” page –Activate by clicking the GoTo button –“GoTo” will immediately change to “Stop” –Watch the rising stage on the CCD monitor –If the stage is in danger of hitting the detector or pole piece, immediately click “Stop” –“Escape” is an alternative “Panic button”

“"When I Use a Word, It Means Precisely What I Want It To Mean....“ Humpty Dumpty In the lexicon of Leo, “Beam current” is the current leaving the filament and “Probe current” is an approximation to the current incident on the sample, usually high by about a factor of two. From FEI, “Beam current” is an excellent approximation to the current actually striking the sample.

Low vacuum Why?

Polystyrene balls High vacuum, 16 kX

Polystyrene balls High vacuum, 100 kX

Polystyrene balls Low vacuum, 16 kX

Polystyrene balls Low vacuum, 100 kX LVD. Helix detector in immersion mode will improve image by approximately one order of magnitude!

Low vacuum Why? –For non-conducting samples –To avoid rapid deposition of crud on your sample. ETD does not work New detector must be installed…while wearing gloves –LVD is relatively cheap and adequate for images up to about 50 kX –Helix is very expensive but gives killer images on non-conducting samples to 500 kX or more! PLA must be installed sufficiently tightly that it does not leak and kill the column “WD” must be redefined if a PLA has been installed!

Low vacuum cont’d You get to low vac faster if you start by going through high vac Start with the minimum water pressure Increase water pressure by clicking on the right arrow –Observe image on screen –Image will get brighter; reduce brightness! –When image brightness no longer increases with water pressure, experiment with small changes

Adjusting water pressure Range: 0.08 – 1.5 Torr 10 – 200 Pa Image brightness will increase with water pressure. Increase water pressure until image stops getting brighter!

Pressure limiting Aperture (PLA)