Deceleration electrode configuration for ultra-low energy ion implanter

摘要

A deceleration electrode for a high-energy, ultra-low ion implanter is provided. The deceleration electrodes are “tilted” (i.e., not perpendicular with respect the ion beam axis. The deceleration electrode reduces the energy of the ion beam and simultaneously separates neutral particles out of the ion beam. The length of the deceleration electrode is slightly longer than a conventional deceleration electrode. However, because the device functions to also separate neutral particles out of the ion beam, the need for a separate neutral particle separation device is eliminated. Thus, the compact design of the dual function electrode configuration permits a shortening of the distance that a high-current, ultra-low energy ion beam must travel to the target wafer. Further, because the neutral particles can be almost completely separated from the ion beam, the decel ratio may be set high enabling an ultra-low energy, high current ion beam. In the tilted decel apparatus of the present invention, a plurality of decel electrodes having openings are arranged in an inclined manner against the axis which is perpendicular to the base axis of a beam passage. An ion beam impinging with a predetermined ion beam offset distance and inclination angle passes through gaps formed between the decel electrodes and thus, an ion beam is decelerated and neutral particles are separated from the ion beam. Thus, an ion beam can be formed having a high current, low neutral contamination, and ultra-low energy.