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LIQUID METAL ION SOURCE |
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Principal Investigator: J. GIERAK
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TECHNICAL DESCRIPTION
This invention describes liquid metal ion sources, where ions are produced from a supply metal which covers a point made of a refractory metal.
By applying an intense electrical field under vacuum, between this point and an extraction electrode, ions are emitted according to a field evaporation mechanism. This emission is localised at the apex of the point. The size of the emissive area is approximately a few nm2 for an emission current of about 2 µA.
These sources are used in focused ion beam machines which play an increasingly important part in the techniques of microelectronic manufacturing.
At present, these machines almost exclusively use ion sources of liquid gallium metal. The use of lighter ions means that the size of ionic probes can be reduced. Increasing resolution of existing machines, by simply changing the source. Furthermore, for implantation applications, a light element is interesting since it penetrates more deeply into the material than a heavy element, with the same energy.
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