| 摘要 |
PURPOSE:To make it possible to remove contamination of an aperture, optical parts, etc., while maintaining vacuum-state thereof by housing a rare gas inlet, an ion beam generator, a magnetic coil for plasma and a coil for ion- neutralization in a tube. CONSTITUTION:Ar gas is put in a plasma-state by introducing rare gas (Ar) maintained in a vacuum-state into a tube 21 through a rare gas inlet 33 and applying voltages to a cathode 44, an anode 45 and a magnetic coil 35. Ar<+> ion beam is accelerated and pulled out into the tube by controlling a control grid 46 and a pulling out grid 47. The surface of an aperture 31, for example, is scanned and irradiated with Ar<+> ion beam by controlling an alignment coil 23 or a sub-deflector 25. By way of application of a voltage to a filament 37 for ion-neutralization provided just before the aperture 31, Ar<+> ion is neutralized just before it and Ar atoms are guided to collide with the surface of the aperture 31 for etching. Therefore, contamination can be removed.
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