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Proceedings Paper

Phase-shift mask applications
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Paper Abstract

Phase-shifted masks (PSMs) promise significant performance benefits for conventional optical lithography. By simultaneously enhancing resolution and depth of focus (DOF), some PSM techniques offer lithography improvements equivalent to more than a 30% reduction of exposure wavelength. Existing wafer exposure equipment can be adapted to PSM use without extensive modification. However, widespread use of PSM technology must await the creation of a PSM infrastructure, including automated generation of PSM patterns, new mask-making materials, and production worthy PSM manufacturing equipment and methods. Modified CAD software, phase layer mask exposure, phase layer deposition, etch, inspection, repair, and other supporting equipment are still in research or development phases. The integration of PSM methodologies and processes to mask and wafer production facilities has not yet begun. In this paper PSM manufacturing and application issues will be examined, with emphasis on PSM reticle printing, PSM reticle requirements and PSM manufacturing alternatives. The authors report on the performance of a scanned laser mask lithography system optimized for printing multilayer phase-shift masks. This system leverages the sub-half micron printing performance of the ATEQ CORE-2500 combined with an optical alignment system. The use of 363.8 nm exposure wavelength offers significant advantages for making PSMs. Chrome alignment marks under dielectric phase and resist layers are accurately and nondestructively acquired with a nonactinic illumination system. The exposure wavelength, near i-line, does not cause or react to dielectric substrate charge. Optimum performance is achieved with common i-line resists which also provide ideal process performance for phase layer deposition and dry etching.

Paper Details

Date Published: 1 July 1991
PDF: 11 pages
Proc. SPIE 1463, Optical/Laser Microlithography IV, (1 July 1991); doi: 10.1117/12.44806
Show Author Affiliations
Peter D. Buck, ATEQ Corp. (United States)
Michael L. Rieger, ATEQ Corp. (United States)

Published in SPIE Proceedings Vol. 1463:
Optical/Laser Microlithography IV
Victor Pol, Editor(s)

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