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Proceedings Paper

Automated design of halftoned double-exposure phase-shifting masks
Author(s): Yao-Ting Wang; Yagyensh C. Pati; Hisashi Watanabe; Thomas Kailath
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Paper Abstract

In our earlier work, we have proposed an efficient algorithm for phase- shifting mask design of an arbitrary IC pattern. Experimental results have shown that the algorithm works well for patterns such as gratings, contact-holes, U-patterns, etc.. In this paper, we use the concept of moment expansion to give a rigorous proof of the well-known fact that two-phase masks such as alternating phase-shifting masks or attenuated phase-shifting masks possess a better depth of focus; thus, our proposed double-exposure masks have depth-of-focus enhancement property. In addition, we also investigate the quantization problems related to our algorithm and develop a new quantization scheme based on the so-called halftoning techniques, which is commonly used in the printing industry to render the illusion of the continuous-tone images on binary output devices such as laser printers. Simulation results have shown that the new quantization scheme performs very well even for much larger and complicated patterns. Currently, empirical verification is underway in cooperation with HP ULSI Research Laboratory, Palo Alto, CA.

Paper Details

Date Published: 26 May 1995
PDF: 12 pages
Proc. SPIE 2440, Optical/Laser Microlithography VIII, (26 May 1995); doi: 10.1117/12.209261
Show Author Affiliations
Yao-Ting Wang, Stanford Univ. (United States)
Yagyensh C. Pati, Stanford Univ. (United States)
Hisashi Watanabe, Stanford Univ. (United States)
Thomas Kailath, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 2440:
Optical/Laser Microlithography VIII
Timothy A. Brunner, Editor(s)

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