| 摘要 |
PURPOSE:To project on a sample a rectangular beam image having a most adequately adjusted current density, by arbitrarily changing a spot size of beam with a zoom lens mechanism when forming a cross-over image with beam shaping apertures. CONSTITUTION:A deflector 4 is disposed between an electron gun 1 and an exposure sample 13 via a zoom lens mechanism 3 consisting of electron lenses 2a-2c. A lens 7 is disposed under the deflector 4 via a first aperture 6 having two orthogonal edges 5. Under the lens 7, a deflector 8 and a second aperture 10 having orthogonal edges 9 are provided. Between the second aperture 10 and a sample 13, a deflector 12 is provided via three electron beam condensing lenses 11a-11c. A beam image is formed on the aperture 6 by the zoom mechanism 3 of the above-described structure to obtain a rectangular pattern restricted by the edges 5. The beam is further turned to a desired size of a rectangular pattern by the edges 9 of the aperture 10. The spot size of beam is changed by these two pairs of edges 5, 9 to project a beam image of a predetermined current density on the sample 13. |
