| Research Abstract |
The major demand for the scanning electron microsropy (SEM) has been in its high magnification, and the maximum resolution of around 0.5nm was attained. However, it is not always true that the current type of the SEM brings the best performance in all applications. The current SEM always uses an electromagnetic system for the electron lens and for the deflection, and it inherently has an inferiority in several characteristics, such as the magnetizing delay and the hysteresis. If we use the electrostatic system, image acquisition can be very fast and stable, and it will be a light and compact system and consume less electric power. Although the electrostatic SEM has been left behind the race to get higher spatial resolution because of the difficulties in electrical insulation and consume less electric power. Although the electrostatic SEM has been left behind the race to get higher spatial resolution because of the difficulties in electrical insulation and in the production of accurate
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shape of electrodes, it still has interesting features in a limited field, such as at low accelerating voltages. The aim of this research is to develop an electrostatic SEM, and this paper sumarizes several aspects in the development.
Aspects concerned are the following : (1) vacuum system, (2) electron optics including the structure of the electron gun and voltages to be applied to every electrode, (3) signal detection using a photo-diode, (4) hard-ware and soft-ware of the scanning system of the electron beam, the signal processing system, the image analyzing system, and the interface to a personal computer, etc. Using the developed system, several electron beam parameters are obtained, and some SEM images are obtained. Since the resolution of the image obtained by the system is not sufficient, new electron optical system is proposed by a numerical calculation. At last, electron scattering phenomena in a specimen are simulated and the SEM signal contrast is theoretically obtained for a prediction of the surface topographic features. Less
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