| 摘要 |
PURPOSE:To focus ion beams on the effective refraction point of a beam refractor so as to refract the beams under the condition that chromatic aberration does not occur by providing an ion beam converging lens at the preceding stage of an ion beam refractor, and providing a means capable of monitoring beam converging state near a beam refractor. CONSTITUTION:Ions are drawn out from the ion source 1 of a secondary ion mass analyser and are accelerated and then, scanning voltage signal is given from a deflecting power source 19 to a deflecting electrode 4, and primary ion beams 14 are made to scan. Hereupon, a secondary ion detector 7 detects the secondary ions emitted from an aperture 5, and that signal is made the input of a CRT 12 as a brightness modulation signal so as to obtain the secondary electron image of an aperture 5. While observing this secondary electron image, voltage which is given from a lens power source 8 to a electrostatic lens 3 is adjusted so as to focus the ion beams 14 on the aperture 5. Hereafter, the deflecting power source 4 is cut to stop the scanning of the beam 14, and the beam 14 passes through the hole of the aperture 5 and reaches the inside of an electrostatic deflecting system 6. |
