ENDCAP FOR INDIRECTLY HEATED CATHODE OF ION SOURCE

摘要

An ion source embodying the present invention is for use in an ion implanter. The ion source comprises a gas confinement chamber having conductive chamber walls that bound a gas ionization zone. The gas confinement chamber includes an exit opening to allow ions to exit the chamber. A base positions the gas confinement chamber relative to structure for forming an ion beam from ions exiting the gas confinement chamber. A portion of a cathode extends into an opening in the gas confinement chamber. The cathode includes a cathode body defining an interior region in which a filament is disposed. The cathode body comprises an inner tubular member a coaxial outer tubular member and an endcap having a reduced cross section body portion with a radially expending rim. The endcap is pressed into the inner tubular member. The filament is energized to heat the endcap which, in turn , emits electrons into the gas ionization zone. The filament is protected fro m energized plasma in the gas ionization zone by the cathode body.