Paper
30 July 2002 Method of Zernike coefficients extraction for optics aberration measurement
Yoshihiro Shiode, Shuuichi Okada, Hiroki Takamori, Hideki Matsuda, Sachiko Fujiwara
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Abstract
With recent progress in resolution enhancement techniques, requirements for exposure tools, specifically optics aberration, are becoming severer. Some simple ways to allow aberration measurements to be performed on exposure tools have been reported and made commercially available. These methods, however, do not seem to go much beyond monitoring of aberration changes while the accuracy of absolute values is left unclear. This paper describes a new approach of optics aberration measurement. With this approach, an optimum effective light source and patterns to be measured have been designed for analysis of Zernike polynomials that represent the wavefront of optics. By measuring the shift of images printed from the patterns with the light source, specific Zernike coefficients can be extracted. This new technique can also be applied to any conventional lens aberration tests using SEM. Same as the above Zernike coefficients extraction, just measuring the displacement of the images that are formed from optimum mask patterns with an optimum light source will provide a conventional SEM value. Simulations to compare the new technique with the conventional SEM showed a very good correlation with each other as expected. Experimental results are discussed to determine the accuracy of the new technique.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yoshihiro Shiode, Shuuichi Okada, Hiroki Takamori, Hideki Matsuda, and Sachiko Fujiwara "Method of Zernike coefficients extraction for optics aberration measurement", Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); https://doi.org/10.1117/12.474530
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CITATIONS
Cited by 7 scholarly publications and 7 patents.
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KEYWORDS
Scanning electron microscopy

Monochromatic aberrations

Light sources

Zernike polynomials

Error analysis

Optical testing

Wavefronts

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