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Proceedings Paper

Gradient phase-shifter transitions fabricated by ion milling
Author(s): Anton K. Pfau; Edward W. Scheckler; David M. Newmark; Andrew R. Neureuther
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Paper Abstract

Abstract Non printing phase transitions will be useful for the general application of phase shifting masks for projection lithography. Phase shifter transitions with a moderate variation of the transmitted light were fabricated using ion milling. A progressing shadow and a corresponding variation in etch depth along the transition was achieved by changing the tilt angle of the sample during the process. Simulations show the improved performance of a gradient transition as compared to step transitions with one 90° intermediate layer. Transitions featuring a continuous slope exhibit reduced linewidth variation and smaller intensity dips. The gradient transitions were formed in theSi02 phase shift layer on top of the chromium layer on the masks. The ion milling with rotating sample was simulated to predict the slope shape and etch rates. The predictions obtained from the etch simulations were in agreement with experimental results. Ion milled gradient transitions were tested by exposing and developing positive photoresist. The resist pattern verified the simulation results.

Paper Details

Date Published: 1 June 1992
PDF: 9 pages
Proc. SPIE 1674, Optical/Laser Microlithography V, (1 June 1992); doi: 10.1117/12.130354
Show Author Affiliations
Anton K. Pfau, Univ. of California/Berkeley (United States)
Edward W. Scheckler, Univ. of California/Berkeley (United States)
David M. Newmark, Univ. of California/Berkeley (United States)
Andrew R. Neureuther, Univ. of California/Berkeley (United States)

Published in SPIE Proceedings Vol. 1674:
Optical/Laser Microlithography V
John D. Cuthbert, Editor(s)

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