ION SOURCE FOR ION IMPLANTATION HAVING SIMPLE AND LONG-LIFE NEGATIVE ELECTRODE

摘要

PURPOSE:To simplify a system and improve its service life by providing an intermediate electrode between a discharge negative electrode and a positive electrode for giving a gas pressure gradient and by enabling electric discharge carrier gases to be discharged at two positions of a plasma region and an ion beam region. CONSTITUTION:A primary intermediate electrode 7 having a built-in permanent magnet and a secondary intermediate electrode 8 having a built-in air-core coil are arranged between a negative electrode 6 and a positive electrode 5 of Ta-LaB6 complex type, so that gas pressure will be given a gradient to make a sheet form. In addition, a plasma flow 3 bent 90 degrees by a permanent magnet 15 is formed near the positive electrode 5. Electric discharge carrier gases are discharged from an exhaust pipe 11 by using an exhaust pump 1 and from another exhaust pipe 12 at the outlet of an ion beam where an outlet electrode 9 and an auxiliary electrode 10 are provided, by using another exhaust pump 2. The treatment of carrier gases by using both pumps 1 and 2, therefore, ensures the improvement of ion source efficiency, the simplification of the ion source and the improvement of its service life.