FEI Scios 2, Руководство пользователя

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System Options: I-Beam Charge Neutralizer
C O N F I D E N T I A L – FEI Limited Rights Data 7-33
Balancing Electron and Ion Beam Currents
If your image is still too white and lacking details after you started the charge neutralizer and slightly reduced the
contrast, you probably have too high electron beam current compared to ion beam current. The electron beam is
de-sorbing ions from the surface, which masks the gallium ion-induced signal (the electron-stimulated

de-sorption). To rectify the problem try the following suggestions:
• Reduce the neutralizer grid voltage to reduce the beam current. The details should become visible as you
achieve the balance between ion and electron currents.
• Fine-tune the neutralizer grid voltage settings to a level appropriate for your application; the exact value is
sample-dependent.
• If you continue to reduce the neutralizer grid voltage you will reach a switch point where there are just not
enough electrons to compensate the charging anymore. If you have gone below this point slightly increase the
neutralizer grid voltage again until the charging disappears. Now you have reached the optimum working
condition with the best possible contrast of your charge compensated secondary ion imaging.
If you are still unsatisfied with the image, adjust the beam energy (50 eV, for example) and check the results.
In case the electrons generation does not start, slowly increase the filament current.
Remarks
• Checking that the Charge Neutralizer is functioning can be made using a glass sample (FEI part nr 22805 Rev A).
• When patterning is paused the Charge Neutralizer stays on.
• When a Snapshot / Photo functionality is performed with the ion beam while patterning with the ion beam is
active the Charge Neutralizer should stay unblanked.
• When a snapshot / photo is performed with the electron beam while the ion beam patterning and Charge
Neutralizer are active, the Charge Neutralizer is automatically blanked and unblanked. This will enable the use of
electron beam frame grabbing during patterning.
• When an electron beam frame grabbing is performed during ion beam imaging, the Charge Neutralizer will
blank and automatically unblank automatically when switching back to ion beam imaging.
• In iSPI mode the Charge Neutralizer cannot be used.