Configuration – Beam/SEM

Overview

The Aperture Position and Beam parameters are accessible through the Beam/SEM tab which can be opened by clicking on the dedicated icon.

Aperture Position

In the Aperture Position sub-window, four aperture sizes are available. 

A1 is 40 µm with beam current in the pA range, and is used exclusively for SEM imaging.

A2 is 70 µm and uses beam currents up to several hundred pA. It may be used for SEM imaging as well.

A3 is 200-µm and uses beam currents higher than 100 nA.

A4 is 150 µm and sustains beam currents between 0.5 nA and 100 nA. This aperture is equipped with the closed-loop beam current control enabling excellent long-term stability.

Beam

In the Beam sub-window, ‘Beam Blanking’ is applied during stage movement, ‘Dist. Maxi (µm)’ being the distance traveled by the stage above which ‘Beam Blanking’ is activated. ‘Mini Focus’ and ‘Maxi Focus’ options lay within the limits of 0 to 4095 respectively for the C3 lens.

The Screen Size (mm) allows users to set the proper screen width of the real-time monitor for the selected magnification, using the ‘Mag’ (magnification) option located in the SX-Control program.

The Maxi HV (kV) function sets the upper limit for the incident electron beam energy.

‘FC Deflection Corr.’ corresponds to the coefficient applied for electrostatically deflecting the beam in the Faraday Cup in order to get the maximum beam current. This is only visible in the SX-FIVE instrument configuration.

The last option in the Beam sub-window is called ‘Reg. by suppressor (>50 nA)’ and is also only available with a source equipped with a FEG. By default, above 50 nA, the controlled close-loop works by adjusting the suppressor value, which is activated by ticking the corresponding checkbox.