Automatic pattern positioning of scanning electron beam exposure

When making a pattern for a solid-state device from a silicon wafer coated with photoresist by the scanning electron beam exposure technique, the positioning accuracy of the pattern is as important as its resolution and dimensional accuracy. A pattern positioning system automated by an electronic computer which is included in the electron beam exposure apparatus type JEBX-2B, is introduced and described. Information conveyed by backscattered electrons from the wafer surface is utilized as a signal which detects the wafer locus and automatically corrects any x-, y-directional and rotational errors. It is shown that the positioning accuracy is within 0.5 µm. It can be improved under some limited conditions.