Alignment Focus Optimization and Image Contrast

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概要

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• In LSI mass production, an alignment sensor must be installed in an exposure system to detect the pattern position accurately even if the pattern condition is changed. To satisfy such a requirement, the defocus effect of improving the image contrast is studied. Particularly under optical conditions with large illumination $\sigma$, the theory of image profile change induced by defocus is clarified in this paper. For a field image alignment sensor (FIA) with large illumination $\sigma$, FIA focus optimization (FFO) is developed as a technique that realizes alignment with both high accuracy and better image contrast by optimized defocus. FFO makes this possible regardless of the pattern phase and/or pattern duty ratio. The effects are confirmed by simulations and experiments. The versatile advantages of FFO for LSI production are confirmed.

• 2005-08-15

著者

• Sugaya Ayako

  The Fifth Development Section, Optical R&D Department, Optical Technology Headquarters, Core Technology Center, Nikon Corporation, 6-3 Nishi-Ohi 1-chome, Shinagawa-ku, Tokyo 140-8601, Japan

関連論文

• Alignment Focus Optimization and Image Contrast
• Tool-Induced Shift and Pupil Transmittance Distribution in Measurement Optics
• Alignment Focus Optimization and Image Contrast

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