Paper
30 October 2007 Characterization and monitoring of photomask edge effects
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Abstract
An experimental technique for quantitatively characterizing edge effect contributions in transmission through thick photomasks is described and evaluated through electromagnetic simulation. The technique consists of comparing the 0th order transmission for various duty cycles to the expected experimental behavior from a thin mask model. The real electric field component from the edges is proportional to the shift in the position of the minimum energy in the 0th order field away from the expected thin mask location. The square root of the minimum 0th order diffraction energy normalized to a clear mask gives the imaginary edge contribution. The results indicate that Alternating Phase Shifting Masks (ALT-PSM) and Attenuating Phase Shifting Masks (ATT-PSM) technologies have significant edge effects on the order of 0.1λ to 0.2λ per edge respectively, as well as polarization dependence. For periods of 2 wavelengths and larger these edge contribution values are nearly independent of pitch. The existence of an imaginary (or quadrature) phase component is shown to result in an additive linear variation of line edge shortening through focus. This tilt can be interpreted as a focus shift of the normal parabolic behavior and is about 0.5 Rayleigh units (RU). This focus shift depends to some extent on the surrounding layout as well as the feature itself.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Marshal A. Miller, Andrew R. Neureuther, Daniel P. Ceperley, and Juliet Rubinstein "Characterization and monitoring of photomask edge effects", Proc. SPIE 6730, Photomask Technology 2007, 67301U (30 October 2007); https://doi.org/10.1117/12.746805
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Cited by 2 scholarly publications.
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KEYWORDS
Photomasks

Glasses

Finite-difference time-domain method

Phase shifting

Phase shifts

Polarization

Dielectrics

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