| 摘要 |
<p>PURPOSE:To facilitate the inspection of a limiting aperture by observing a current which flows to a monitor aperture while deflecting an ion beam. CONSTITUTION:A voltage impressed on the a monitor electrode 6 is varied gradually to deflect the ion beam and then a current shown in a graph is observed at the monitor aperture 7. A CPU 11 sends an indication for varying the impressed voltage gradually to a D/A converter 12 and an aperture current value is inputted from an A/D converter 15 for each voltage value to generate a graph on a memory. Then the width (d) of a curve corresponding to, for example, a 10 - 90% range is calculated and displayed on a CRT 16. This width (d) is regarded as a target detected value indicating the ion beam diameter. This ion beam diameter is determined by the opening part of the limiting aperture 4, so this detected value (d) indicates the opening part diameter of the aperture 4.</p> |
