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Applied Optics

Applied Optics


  • Editor: Joseph N. Mait
  • Vol. 49, Iss. 31 — Nov. 1, 2010
  • pp: 5959–5963

Moiré-based focusing and leveling scheme for optical projection lithography

Wei Yan, Yong Yang, Wangfu Chen, Song Hu, and Shaolin Zhou  »View Author Affiliations

Applied Optics, Vol. 49, Issue 31, pp. 5959-5963 (2010)

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During the process of integrated circuit manufacturing, positioning techniques, such as leveling and focusing, are among the key factors in improving the resolution of optical lithography and related lithographic tools. We present a measurement scheme based on the proverbial moiré effect for focus positioning in projection lithography. The framework of this scheme is based on a fundamental model of dual gratings and can also be decomposed into a dual 4 f optical system. In this scheme, the moiré effect that usually occurs in the superposition of two gratings also comes forth when they are located at two sides of the dual 4 f optical system, which puts one grating together with the other by optical imaging. Related results of this basic dual-grating model have been concluded. The framework of this scheme is built, and the complex structure is explored when similarly broken down to a basic model of two superposed proximity gratings. Finally, experimental results and corresponding analyses indicate that focusing resolution at the nanometer level can be realized by this scheme.

© 2010 Optical Society of America

OCIS Codes
(050.1950) Diffraction and gratings : Diffraction gratings
(070.2580) Fourier optics and signal processing : Paraxial wave optics
(220.2560) Optical design and fabrication : Propagating methods
(220.3740) Optical design and fabrication : Lithography

ToC Category:
Active and Adaptive Optics

Original Manuscript: January 5, 2010
Revised Manuscript: March 5, 2010
Manuscript Accepted: April 26, 2010
Published: May 19, 2010

Wei Yan, Yong Yang, Wangfu Chen, Song Hu, and Shaolin Zhou, "Moiré-based focusing and leveling scheme for optical projection lithography," Appl. Opt. 49, 5959-5963 (2010)

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