| 摘要 |
PURPOSE:To perform ion implantation while neutralizing the space charges efficiently by arranging an electron gun for projecting low energy electrons at the side of Farady cage while applying weak magnetic field in the direction perpendicular with the motion of electrons by means of a permanent magnet. CONSTITUTION:An ion beam 4 is implanted through Farady cage 5 into a wafer 1 placed on a platen 3 in vacuum chamber 2. Here, an electron gun 8 having a filament 6 and a lead-out electrode 7 is arranged at the side of the cage 5 to project an electron beam having energy in the order of 100eV into the cage 5 while a permanent magnet 11 for applying weak magnetic field of about 3 gause in perpendicular direction against the motion of electrons is provided. Then the electrons are moved in cycloidal in a plane perpendicular against the magnetic field to exist many low energy electrons in the ion beam 4. Consequently, the space charges are neutralized efficiently while the temperature rise is suppressed to protect the wafer 1 from contamination.
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