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X Ray Alignment Using Electron Collector on Mask

IP.com Disclosure Number: IPCOM000085149D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Eastman, DE: AUTHOR [+5]

Abstract

An alignment procedure is provided for accurately aligning an X-ray absorbing mask and a wafer. An X-ray absorbing mask has an electron-collecting registration mark on it, and a wafer to which the mask is to be aligned has a photoemitting registration mark on it which emits electrons when hit with X-rays. Registration of the mask with the wafer is achieved by using a portion of the registration mark to sense the electrons being emitted by the wafer.

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X Ray Alignment Using Electron Collector on Mask

An alignment procedure is provided for accurately aligning an X-ray absorbing mask and a wafer. An X-ray absorbing mask has an electron- collecting registration mark on it, and a wafer to which the mask is to be aligned has a photoemitting registration mark on it which emits electrons when hit with X- rays. Registration of the mask with the wafer is achieved by using a portion of the registration mark to sense the electrons being emitted by the wafer.

In the figure, a portion of the wafer 2, onto which a pattern is to be deposited by X-ray lithography, contains a metal pattern 4 that emits secondary electrons when exposed to X-rays. The wafer is coated with a layer of resist, not shown, care being taken not to cover the secondary electron emitter elements 4. An X- ray mask 6 contains near one edge, an X-ray absorber pattern 8 and a collector 10 of secondary electrons emitted by wafer X-ray absorber pattern 4.

When the mask and wafer are superimposed to test registry, the X-rays going through absorber pattern 8 will produce secondary electrons in absorber pattern 4, which electrons are collected at elements 10. It is preferred that the absorber pattern 8 be made integral with and be the same pattern as the electron collector pattern 10. A meter 12 measures the amount of secondary electrons collected and a maximum reading is used to determine correct alignment.

The above-described procedure is desirable in that the m...