Ionizer for an ion implanter, ion source comprising this ionizer and method of cooling an ionizer

摘要

An ion source (50) for an ion implanter is provided, comprising a remotely located vaporizer (51) and an ionizer (53) connected to the vaporizer by a feed tube (62). The vaporizer comprises a sublimator (52) for receiving a solid source material such as decaborane and sublimating (vaporizing) the decaborane. A heating mechanism is provided for heating the sublimator, and the feed tube connecting the sublimator to the ionizer, to maintain a suitable temperature for the vaporized decaborane. The ionizer (53) comprises a body (96) having an inlet (119) for receiving the vaporized decaborane; an ionization chamber (108) in which the vaporized decaborane may be ionized by an energy-emitting element (110) to create a plasma; and an exit aperture (126) for extracting an ion beam comprised of the plasma. A cooling mechanism (100, 104) is provided for lowering the temperature of walls (128) of the ionization chamber (108) (e.g., to below 350 DEG C) during ionization of the vaporized decaborane to prevent dissociation of vaporized decaborane molecules into atomic boron ions. In addition, the energy-emitting element is operated at a sufficiently low power level to minimize plasma density within the ionization chamber (108) to prevent additional dissociation of the vaporized decaborane molecules by the plasma itself. <IMAGE>