 enlarged version
enlarged version | | The SEs and BSEs generated at the impact point of the primary electron beam are intercepted by the low electrical field of the GEMINI® column at the sample surface. They are accelerated by the field of the electrostatic lens. Due to the excitation of the objective lens the low-energy SEs are deflected onto the annular high efficiency In-lens SE detector. The high angle BSEs originated close to the impact point of the primary electron beam, are focussed into a beam-waist at the hole of the In-lens SE detector and detected by the integrated EsB detector. A small amount of SEs pass through the hole of the In-lens detector and would be observed by the EsB detector. To prevent detection of these SEs a filtering grid is installed in front of the EsB detector
By simply switching the filtering grid the SEs will be rejected and only the BSEs will be detected. The unique combination of the In-lens SE detector and the EsB detector enables simultaneous imaging and mixing of clear high contrast topography (SE) and pure compositional contrast (BSE).
Below a landing energy of 1.5 kV the filtering grid has the additional function of selecting the desired energy of the BSEs. The operator can select the energy band towards the inelastic scattered BSEs to enhance contrast and resolution. For example, with a landing energy of 1.5 kV and the filtering grid on 1.4kV, the SE will be up pressed and the BSE landing on the EsB detector will be in the range of 1.4 – 1.5kV. |