METHOD AND APPARATUS FOR ION BEAM NEUTRALIZATION

摘要

Method and apparatus for maintaining an ion beam (14) along a beam path from an ion source (12) to an ion implantation station (16) where workpieces are treated with the ion beam. An ion beam neutralizer (44) is positioned upstream from the ion treatment station and includes confinement structure (120) which bounds the ion beam path. An electron source (126) positioned within the confinement structure emits electrons into the ion beam. An array of magnets (124) supported by the confinement structure creates a magnetic field which tends to confine the electrons moving within the confinement structure. An interior magnetic filter field is created inside the confinement structure by a plurality of axially elongated filter rods (208) having encapsulated magnets (224) bounding the ion beam and oriented generally parallel to the ion beam path. This interior magnetic field confines higher energy electrons (300) from leaving the ion beam path and permits lower energy electrons (301) to drift along the ion beam.