Practical Electron Microscopy and Database

Gallium (Ga) is currently the most commonly used LMIS (liquid-metal ion source) for FIB instruments because of many reasons:
        i) Low melting point: Ga has a low melting point (29.8 °C), and thus exists in the liquid state near room temperature.
        ii) Low volatility.
        iii) Low vapour pressure.
        iv) Excellent mechanical, electrical, and vacuum properties.
        v) Excellent emission characteristics, enabling high angular intensity with a small energy spread.
        vi) Ga ions can be focused to a very fine probe size (<10 nm in diameter).

Figure 2489 shows the schematic illustration of dual beam FIB/SEM. The angle (α) between the electron beam and ion beam is normally in the range of 52 and 54°. The description and operation principle of all the components in the system can be found in the online book.

Figure 2489. Schematic illustration of dual beam FIB/SEM.