Characteristics of ion beams from a Penning source for focused ion beam applications

Focused ion beam characteristics, measured by using PMMA resist exposures, show significant improvement of the previously reported results for hydrogen ion beams. A beam current density of >50 mA cm(-2) at 6-7 keV has been obtained over a spot size of 2.3 mu m, estimated from the full width at half maximum of the intensity distribution. A single Einzel lens with magnification of about 0.1 was used. A target current density of >1 A/cm(2) can be achieved with this beam for a lens system with overall magnification of similar to 0.01. In experiments with Ar, both the discharge current and extracted beam current increased by more than a factor of 2 when the discharge cell length was increased by about 25% with respect to the nominal cell length for operation with H. Ar ion beams were extracted with an angular beam intensity of >5 mA sr(-1), brightness (90% beam) of similar to 10(3)A sr(-1) cm(-2) at 10 keV, and energy spread of similar to 4.5 eV. Greatly improved beam characteristics, with brightness >10(4) A sr(-1) cm(-2), are expected by optimization of the source for Ar beams. (C) 1999 American Vacuum Society. [S0734-211X(99)05206-3].