HIGH-INTENSITY SCANNING ION PROBE WITH SUBMICROMETER SPOT SIZE

A liquid-metal gallium-ion source was imaged by unity-magnification single-gap accelerating lens with a postlens deflector to form a focused scanning probe. We report the dependence of the probe diameter and probe current on the lens acceptance half-angle. The results range between probe diameters of 1000 and 5000 Å at currents of 0.12-3.0 nA for half-angles of 1.2-6 mrad. The current density and brightness at the target for the 1000-Å-diam 57-kV probe were 1.5 A/cm2 and 3.3×106 A/cm 2 sr, respectively. Astigmatic probes were also produced with dimensions smaller than 1000 Å.