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Dispersion and detection of signal electrons in environmental SEM
Romanovský, V. ; Neděla, Vilém ; Hutař, O.
The environmental scanning microscope is based on convenient adaptation of classical SEM employing the focused primary electron beam. For the proper function of the electron gun the pressure in this part of the microscopemust be less than 10.sup.-3./sup. Pa. The working pressure in the specimen chamber in environmental microscope reaches the order of hundreds of Pa.Therefore, the effective vacuum separation of these two parts is necessary. This can be obtained by the use of two or more apertures limiting the gas flow. It is also necessary to evacuate the space between the apertures by a vacuum pump of a high pumping speed. The increasing of pressure in the specimen chamber brings some difficulties, especially the dispersion of signal electrons by the influence of interaction with the gaseous environment.
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Combined detector for BSE, SE and BSE+SE detection in a low voltage SEM
Autrata, Rudolf ; Jirák, Josef ; Romanovský, Vladimír ; Špinka, Jiří
Specimen observation at a low accelerating voltage of the electron beam (around 1kV) is a new and attractive technique of scanning electron microscopy. While detection to the signal of secondary electrons (SE) with the help of the scintillation-photomultiplier system described by Everhart-Thornley does not depend on the primary beam energy, the detection of backscattered electrons (BSE), having their energy only a bit lower than energy of the beam, is limited by a low sensitivity of semiconductor or channel plate detectors to channel plate detectors to electrons of energy below 2 keV.
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Fully electrostatic low energy scanning electron column
Romanovský, V. ; El-Gomati, M. ; Frank, Luděk ; Müllerová, Ilona
The exploitation of low-energy electrons for examination of the material surfaces has several advantages. One of them is a small depth penetration of the primary electrons (PE) to the observed material. At low energies the charging effects on non-conductive or slightly conductive specimens are suppressed and also radiation damage of the observed specimen is decreased. Since the secondary electron (SE) yield is high, the signal to noise ratio (SNR) is about one order of magnitude larger than those in microscopes operated at 20kV.
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Influence of magnetic field upon detection in environmental SEM
Romanovský, Vladimír ; Neděla, Vilém
The single-pole magnetic lens has been constructed and placed co-axially with the beam of primary electrons below the specimen holder. A scheme of its configuration is shown in Figure 1. The lens had to be designed with consideration to the size of space available in the specimen chamber. The situation was complicated by the necessity of placing a magnet below the specimen holder. For this reason the height of 30 mm and diameter of 55 mm of the magnetic lens were chosen. The dependency of induction B on the current I through the magnet was measured by a T-meter.
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Imaging of the voltage contrast in environmental SEM
Romanovský, Vladimír ; Autrata, Rudolf
Current methodology of imaging in the scanning electron microscopy is based on the detection of signal electrons that carry topografic and materialcontrast of specimens under study. Electronic devices can be observed because in their standard working mode voltage differences on component surfaces are visualized by means of the voltage contrast. This contrast can be acquired in nearly any commercially available scanning electron microscopeby detection and subsequent analysis of secondary electrons.
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Electrostatic mini SLEEM for surface studies
Romanovský, Vladimír ; El-Gomati, M.
Exploitation of the low-energy electrons is advantageous for several reasons. One of them is their smaller penetration depth into the material, which reveals itself as favourable for the surface analysis. Using the low-energy electrons even causes partial, and in some cases total elimination ofcharging effects at non-conductive or slightly conductive specimens. Slowprimary electrons (PE) cause only reduced radiation damage of specimens.
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Imaging of semiconductor structures in environmental SEM
Romanovský, Vladimír ; Hutař, Otakar
The charging effects are encountered very often when the semiconductor specimens are observed. There are several possibilities how to eliminate these undesirable phenomena. One of the newest methods how to suppress charging of specimens is environmental scanning electron microscopy (ESEM). Ionisation of gas molecules caused by impacts of primary beam electrons and signal electrons in the close vicinity of the specimen surface removes the surface charge. The ionisation detectors used in ESEM enable one to obtain similar information as in classical SEM.
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