| 摘要 |
An ion accelerator for use in an ion beam implanter. The accelerator forms milliampere beams of heavy ions such as boron and phosphorous in a configuration in which the terminal ion source is replaced by a neutral beam injector. The neutral beam is formed at ground by the conversion of a focused beam of positive ions to neutral ions in a charge exchange canal. The neutral beam so formed is stripped of one or more electrons in a gas or vapor filled canal in the high voltage terminal. A 180 DEG analyzing magnet located in the high voltage terminal analyzes and directs a selected charge state to an acceleration tube parallel to the neutral beam injection tube where the selected positive ions are accelerated to ground potential. To extend the energy range of the accelerator below the injection energy, a high voltage insulator is provided to insulate the ground end of the positive ion acceleration tube permitting the acceleration tube and terminal to be uniformly biased at a negative voltage to decelerate the beam to very low energies at a location close to the point of use. In an alternative embodiment, an accelerator assembly includes a 90 DEG analyzing magnet in the high voltage terminal. |
