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Recessed Beryllium Exit Window for an X-Ray Lithography Beam Line

IP.com Disclosure Number: IPCOM000036412D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Rippstein, R: AUTHOR

Abstract

All partially transmissive optical elements in an X-ray beam line create heat. The heat is normally transferred to the walls of the vacuum system through conduction, radiation, and, occasionally, convection.

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Recessed Beryllium Exit Window for an X-Ray Lithography Beam Line

All partially transmissive optical elements in an X-ray beam line create heat. The heat is normally transferred to the walls of the vacuum system through conduction, radiation, and, occasionally, convection.

For an X-ray lithography beam line which allows operation of a step-and- repeat aligner in a room environment, the exit window must be strong enough to withstand one atmosphere of pressure and thin enough to avoid excess absorption of the X-rays. Beryllium (Be) is one material which qualifies for this application. If placed in proximity to the X-ray mask, the heat generated in the window will cause mask distortion.

Referring to the drawings a method which avoids this unwanted heat transfer is to remove the window 15 from proximity to the X-ray mask 26. By providing a helium atmosphere from helium supply line 10 for the longer path required, a small loss of flux due to absorption is realized while providing effective thermal conduction of the heat to the walls of the window-mounting plate 12 and helium- filled tunnel 20. Tunnel 20 is purged of helium at a pressure of one atmosphere. The Be foil is clamped at position 15. X-ray synchrotron source 25 is to the right. The drawings show a configuration to be used in a beam line. The curved exit port 22 for the beryllium window 15 is seen in the front view. This shape allows effective window cooling through conduction to the mounting surfaces while s...