Paper
15 November 1999 Influence of first lens on magnification optimization method in two-lens FIB optical system
Kiyoshi Sakaguchi, Tetsu Sekine, Hiroshi Shimada
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Abstract
Focused ion beam (FIB) tools are widely used for scanning ion microscope (SIM) image observation and for ion milling in semiconductor and other industries. The demands for a higher resolution in SIM and for a more intensive beam in ion milling are increasing. Limiting in 2 lenses FIB optical system, we studied the influence of the first lens's properties, particularly magnification M1 and extraction voltage Vext, on the attainable beam diameter through an optimizing calculation. From this point of view, we investigated the attainable smallest beam size in the low current region by varying the parameters of the first lens, and found out that the lower extraction voltage has an advantage for getting a smaller beam. It is of big concern, as far as emission is possible, how much the extraction voltage can be minimized. It is related to M1, and the change of Vext between 5 and 12 kV produces the beam size variation of about 1 to approximately 1.5 nm. It is not negligible compared with the beam size of approximately 5 nm, which is attainable today. Therefore, we have a possibility to reduce the beam size by reviewing the first lens properties including Vext. Finally, a guide line is shown for the FIB column design from this point of view.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kiyoshi Sakaguchi, Tetsu Sekine, and Hiroshi Shimada "Influence of first lens on magnification optimization method in two-lens FIB optical system", Proc. SPIE 3777, Charged Particle Optics IV, (15 November 1999); https://doi.org/10.1117/12.370127
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KEYWORDS
Electrodes

Ions

Chromatic aberrations

Gallium

Charged particle optics

Lens design

Objectives

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