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Proceedings Paper

Multiple-focus exposure in strong phase-shift lithography: improvement of CD-focus characteristics and CD controllability
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Paper Abstract

To improve the CD controllability of isolated lines, we have developed a new method using multiple-focus exposure in alternating phase-shift lithography. In this paper, the imaging performance such as DOF, exposure latitude, mask linearity, and CD controllability is discussed through both experiments and simulation. Multiple-focus exposure experiments were performed using a KrF scanner by giving a tilt offset between the image focal plane and the wafer leveling plane. For the conventional alternating phase-shift method, the CD-focus curve showed a strong concave shape and thus the DOF was rather small. By applying multiple-focus exposure, the shape of the CD-focus curve changed from concave to flat, and therefore the DOF was much improved. We have also found that the CD controllability considering focus errors can be improved by our method.

Paper Details

Date Published: 14 September 2001
PDF: 10 pages
Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001); doi: 10.1117/12.435768
Show Author Affiliations
Masashi Fujimoto, NEC Corp. (Japan)
Tadao Yasuzato, NEC Corp. (Japan)


Published in SPIE Proceedings Vol. 4346:
Optical Microlithography XIV
Christopher J. Progler, Editor(s)

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