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Heat Shield for Beryllium Window Integrity in Storage Ring X-Ray Lithography

IP.com Disclosure Number: IPCOM000045941D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Grobman, WD: AUTHOR [+3]

Abstract

In X-ray lithography with a synchrotron beam, a thin window (usually beryllium (Be)) separates the ultra-high vacuum storage ring from the lithography chamber. A thin metal foil placed ahead of the window would absorb low energy radiation and thereby reduce heating of the window.

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Heat Shield for Beryllium Window Integrity in Storage Ring X-Ray Lithography

In X-ray lithography with a synchrotron beam, a thin window (usually beryllium (Be)) separates the ultra-high vacuum storage ring from the lithography chamber. A thin metal foil placed ahead of the window would absorb low energy radiation and thereby reduce heating of the window.

In X-ray lithography at a storage ring, a Be window separates a He-filled chamber from the beamline, which connects the chamber to the ultra-high vacuum ring. The Be window must be close to the X-ray mask and wafer so that the He path does not attenuate the useful flux around photon energies 800 < hv < 1800 eV. Consequently, the Be window is large and under significant stress, which can be potentially near the Be yield stress limit, since the window is kept thin to enhance throughput. During X-ray exposure, copious soft radiation from the ring - radiation which is not useful for lithography - is absorbed by the Be window and heats it. The temperature rise caused by such heating is typically large enough to significantly lower the yield limit stress, causing an enhanced danger of window failure.

The obvious solution to the problem is to use a thicker foil. However, a thicker window severely compromises system throughput by reducing the usable X-ray flux. We propose to intercept the X-ray beam, in the beamline between the storage ring and the Be window, with a thin metal foil which acts as a high-pass filter for p...