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Proceedings Paper

Alternative soft x-ray source for step-and-scan lithography
Author(s): Melvin A. Piestrup; Michael W. Powell; Louis W. Lombardo
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Paper Abstract

As a synchrotron or excimer-laser alternative, this paper presents transition radiation as a soft x-ray source for step and scan lithography. This source offers high brightness, collimation, modest operating vacuum, ideal spectral characteristics and moderate cost. The x-ray radiation is emitted in a forward cone in the 0.5-1.8 keV range and generated by electron beams with moderate energies between 25-100 MeV. The radiator target consists of many thin metal foils of beryllium, which are separated by a vacuum. The target output power wavelength can be optimized for highest photoresist sensitivity, window transmission and minimal spurious exposure. For collimation, ellipsoidal-grazing-angle optics or capillary optics increase the mask/wafer image plane into a finite-line image. As in synchrotron systems, the line is then scanned for dose uniformity. For a 70-MeV 400-(mu) A-average-current electron beam, the total x-ray power delivered through the 1-micrometers Si window and 1-micrometers Si substrate to the photoresist in the photon energy in the desired bandwidth (0.5 to 1.8 keV) is 16 mW in a 22-mm X 32-mm area. With a 1-mJ/cm2 resist (required for EUV-lithography), the exposure time would be 440 mS.

Paper Details

Date Published: 27 May 1996
PDF: 11 pages
Proc. SPIE 2723, Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing VI, (27 May 1996); doi: 10.1117/12.240481
Show Author Affiliations
Melvin A. Piestrup, Adelphi Technology Inc. (United States)
Michael W. Powell, Adelphi Technology Inc. (United States)
Louis W. Lombardo, Adelphi Technology Inc. (United States)

Published in SPIE Proceedings Vol. 2723:
Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing VI
David E. Seeger, Editor(s)

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