Patent attributes
In an aperture for use in an ion beam optical system having its surface coated with a liquid metal, instability of an ion source attributable to sputtering and re-deposition of an aperture base material is prevented. A focused ion beam apparatus using a liquid metal ion source has an aperture for limiting an ion beam diameter. The aperture has a vessel formed with a recess having, at its surface lowermost point, an aperture hole through which the ion beam passes and a liquid metal mounted on the recess, the liquid metal being used for the liquid metal ion source. Preferably, the aperture may be minimized in area of aperture entrance hole inner surface which exposes the base material by tapering an aperture hole portion, by which the ion beam passes, on the downstream side.
