29 March 2007 Mask enhancement using an evanescent wave effect
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Proceedings Volume 6520, Optical Microlithography XX; 652041 (2007); doi: 10.1117/12.711781
Event: SPIE Advanced Lithography, 2007, San Jose, California, United States
Abstract
State of the art lithography is continually driven to resolve increasingly smaller features, forcing k1 values for lithography processes ever lower. In order to image these difficult features with reliable fidelity, lithographers must increasingly use Resolution Enhancement Techniques (RETs). One such technique that is proposed in this paper uses small, sub-wavelength grooves placed in close proximity to an aperture. These sub-wavelength grooves create evanescent fields bound to the surface between the absorber and the mask substrate, decaying exponentially in lateral directions. In this work we demonstrate the ability to use such Evanescent Wave Assist Features (EWAFs) to enhance the propagating near and far field energy within openings such as slits and contacts. Using a Finite Difference Time Domain model, the effects of these evanescent wave assist features are explored in both the near and far field regions. Several cases of absorber material, feature type, spacing, and illumination will be presented.
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Neal V. Lafferty, Jianming Zhou, Bruce W. Smith, "Mask enhancement using an evanescent wave effect", Proc. SPIE 6520, Optical Microlithography XX, 652041 (29 March 2007); doi: 10.1117/12.711781; https://doi.org/10.1117/12.711781
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KEYWORDS
Chromium

Photomasks

Near field

Lithography

Polarization

Refractive index

Wave propagation

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