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Cascade Beryllium Window Arrangement for X-Ray Lithography

IP.com Disclosure Number: IPCOM000046115D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Gal, LV: AUTHOR [+3]

Abstract

In X-ray lithography with a storage ring (synchrotron), a window separates the high-vacuum storage ring from the lithography sample chamber. In order to reduce X-ray absorption, two windows are proposed instead of one with hydrogen gas in between.

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Cascade Beryllium Window Arrangement for X-Ray Lithography

In X-ray lithography with a storage ring (synchrotron), a window separates the high-vacuum storage ring from the lithography sample chamber. In order to reduce X-ray absorption, two windows are proposed instead of one with hydrogen gas in between.

It is well known that the X-ray absorption of hydrogen gas is about l/2 that of helium gas for X-rays in the l.0-l.5 KeV range. For this reason it could be attractive to use hydrogen instead of helium. Because of the explosive nature of hydrogen, however, it is not the best gas to use in the sample chamber. Hydrogen could be used in the beamline connection tube if a suitable gas separation barrier is established. In order to protect the storage ring while reducing the high X-ray absorption of the helium gas backfilling the beamline tube, two or more spaced X-ray transmitting windows could be used.

The strength of a window of given thickness to a uniform load is a function of the diameter of the window and its thickness. A thin, but large window 10 isolates the sample chamber 12 from the beamline 14. A low absorption gas, such as H2, fills the space 16 between windows 10 and a further window 18.

The pressure (P1) of the H2 gas is held close to, but less than the pressure (P2) in the sample chamber 12 so that the thickness of window 10 can be small, thus absorbing a minimum of the X-ray flux. Since window 18 may be smaller in diameter (the X-ray flux diverges), it...