| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable to obtain an S/N ratio of a secondary electron detecting signal of a desired size, even when a radiation amount of a primary electron beam is reduced in order not to damage electric characteristics of a substrate. <P>SOLUTION: An electron gun 1-9 is set to be actuated within a space charge restricted area by monitoring a heating current vs. an electron gun current or an anode voltage vs. the electron gun current. A cathode of the electron gun 1-9 is constituted of a single crystal LaB<SB>6</SB>, the electronic beams emitted from the electron gun 1-9 are narrowed to a value of a desired beam diameter D with a condenser lens 2-9 and an objective lens 9-9, and a picture is shown on a substrate 10-9. A secondary electron emitted from a wafer is detected by a detector 41-9, and converted into image data by an image processing part 42-9, and a prescribed pattern test is carried out. Because the electron gun 1-9 is actuated within the space charge restricted area, shot noises become smaller, and the S/N ratio of the detected signal becomes larger, even when the radiated amount of the primary electron beam is made smaller. <P>COPYRIGHT: (C)2004,JPO |
