Chapters authored
DC Parallel Ribbon Ion Beams for High-Dose Processes
Ribbon beams of heavy ions have advantages over cylindrical beams, including higher space-charge limits. History of use goes from Calutrons, Freeman and Bernas ion sources, to the first ion implanters in the 1970s. In the 1990s, 300 mm uniform parallel mass-analyzed ribbon beams were developed to enable precise doping by mechanically scanning a substrate through the ion beam in one dimension. Ion species included the primary dopants boron, phosphorus and arsenic, but many others are also used. Such sources can produce currents of heavy ions with linear current densities at the source of the order of 10 mA/cm, but these sources are limited in the beam breadth they can produce. Broader beams are used for flat-panel display manufacture. A new linear source design combines a modified Penning trap with magnetic cusp confinement system, allowing extension of linear sources to meter scale beam breadths, maintaining around 10 mA/cm linear current density. Magnetic analysis of such beams has required new developments because the weight of conventional dipole magnets increases very steeply as the pole gap is increased. A new magnetic configuration has been developed to address this issue, reducing the potential weight of meter-scale analyzed systems by an order of magnitude.
Part of the book: Ion Beam Technology and Applications