MASS ANALYSIS VARIABLE EXIT APERTURE

摘要

A method and apparatus is provided for reducing unwanted isotopes of an ion implantation species from an ion beamline. The apparatus herein disclosed is a mass analysis variable exit aperture that selectively reduces the size of an exit aperture as seen by an ion beam (408). In one embodiment, the variable mass analysis exit is located within the mass analyzer at a location upstream of a resolving aperture and is configured to effectively limit the size of the exit aperture to allow passage of desired implantation isotope(s) while blocking the passage of unwanted implantation isotopes (406). In one particular embodiment, the mass analysis variable exit aperture is mounted in the beam guide which, in turn, is mounted between the poles of the AMU magnet(s). A mechanical drive mechanism enables the blocking structure (402) to be moved into the beam path in a graduated fashion as guided by a control unit tied to beam characteristics.