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Feedback Control of Electron Beams

IP.com Disclosure Number: IPCOM000092546D
Original Publication Date: 1966-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Zeheb, D: AUTHOR

Abstract

The utility of electron beams for work requiring high resolution is well known. Moreover, there is presently no known substitute to electron beams for submicron applications.

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Feedback Control of Electron Beams

The utility of electron beams for work requiring high resolution is well known. Moreover, there is presently no known substitute to electron beams for submicron applications.

In order to realize this potential of electron beams, it is necessary to be able to precisely control the positional accuracy to the beam. Carefully engineered open-loop systems can achieve control to about one micron. Beyond this value the task becomes exceedingly difficult to the point of being impractical if not impossible. It is thus necessary to resort to feedback techniques where an error signal is derived directly off the beam. In optics this can be accomplished by imaging a light source on two or more spots. One is used as the working agent and the others are used to scan some grating structure, physically connected with the work piece, in order to derive a feedback signal.

This approach is not possible with an electron beam. The best techniques to date permit only periodic reregistration of the beam by going over registration marks placed periodically between useful work areas.

In the drawing, a continuous feedback control for an electron beam includes plate 10 on movable worktable 12 which can be moved in the X and Y directions. X grating structure 14 and Y grating structure 16 are mounted rigidly in a position suitable for imaging an area in the center of worktable 12. Plate 10 is coated with a desired metal such as chromium. On top of the chromi...