Electron detection in the intermediate chamber of the variable pressure SEM

Two concepts of the secondary electron detection inside the intermediate chamber of the variable pressure scanning electron microscopy have been discussed. One of them, the two-stage secondary electron detector has been the subject of previous publications. The other one, the intermediate secondary electron detector is an improved solution in respect of its complexity, vacuum demands and dimensions. Both detector systems apply some kinds of scintillators, so they present advantages specific for scintillator detectors but extended to a wide range of gas pressures, from high vacuum to pressures exceeding 10 mbar. The detector functioning is illustrated with computer simulations of electron and ion flow in the input region of the detectors made with use of the MC-SIMION program. This software combines a commercially available program SIMION 3D v.7.0, destined for computations of charged particles trajectories in electric and magnetic fields, and the Monte Carlo one written in the SIMION internal language.