Abstract: A variable aperture assembly (30) is provided for controlling the amount of ion beam current passing therethrough in an ion implantation system (10). The aperture assembly (30) comprises an aperture (44) defined by opposing first and second aperture plates (44A, 44B) through which an ion beam passes; control arms (46A, 46B) connected, respectively, to the first and second aperture plates (44A, 44B); and an aperture drive mechanism (36) for simultaneously imparting movement to the control arms in opposite directions, to adjust a gap (50) between the aperture plates (44A, 44B) to thereby control the amount of current passing through the aperture (44). Each of the opposite directions in which the control arms move is generally perpendicular to an axis along which the ion beam passes. A control system (120) is also provided for automatically adjusting the aperture gap (50) based on inputs representing actual ion beam current passing through the implanter, desired ion beam current, and aperture position.

Abstract: An electron cyclotron resonance ion source for an ion implanter. The source includes an ionization chamber surrounded along its length by an electromagnet. A number of extraction electrodes at an output end of the ionization chamber allow positively charged oxygen ions to pass through apertures in the electrodes. The uniformity of the axially aligned magnetic field in the ionization chamber is extended through the extraction electrode by a magnetically permeable electrode and through use of non-magnetically permeable material to mount others of said electrodes.