Low-voltage probe forming columns for electrons

A new low-voltage high-current column with a Schottky emission gun is presented, which generates an electron probe of 1 keV energy, 20 nA probe current and 50 nm in diameter. Additionally, the secondary electron detection is uniform for a large scan field which makes this column very suitable for wafer inspection and fast electron-beam testing of integrated circuits. A “low-voltage booster” is proposed which can be adapted to a conventional medium-voltage scanning electron microscope to improve its resolution for low-voltage operation. These new systems are compared with other existing low-voltage columns and components, and some principles of low-voltage electron optics are discussed.