The beam brightness of a multicusp-plasma ion source has been substantially improved by optimizing the source configuration and extractor geometry. The current density of a 2 keV He + beam extracted from a 7.5-cm-diameter source operating at 2.5 kW RF power is ~100 mA/cm 2 , which is ~10 times larger than that of a beam extracted from a 5-cm-diameter source operating at 1 kW RF power. A smaller focused beam spot size is achieved with a counter-bored extractor instead of a conventional ("through-hole") extractor, resulting another order of magnitude improvement in beam current density. Measured brightness can be as high as 440 A/cm 2 Sr, which represents a 30 times improvement over prior work.
Mini rf-driven ion sources with 1.2 cm and 1.5 cm inner chamber diameter have been developed at Lawrence Berkeley National Laboratory. Several gas species have been tested including argon, krypton, and hydrogen. These mini ion sources operate in inductively coupled mode and are capable of generating high current density ion beams at tens of watts of absorbed rf power. Since the plasma potential is relatively low in the plasma chamber, these mini ion sources can function reliably without any perceptible sputtering damage of the chamber wall. The mini rf-driven ion sources will be combined with electrostatic focusing columns, and are capable of producing nanofocused ion beams for micromachining and semiconductor fabrications.
Demonstrations of electronic pattern switching and 10× pattern demagnification in a maskless microion-beam reduction lithography system Development of wide range energy focused ion beam lithography system
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