Pellicle-induced aberrations and apodization in hyper-NA optical lithography

Karsten Bubke; Benjamin Alles; Eric Cotte; Martin Sczyrba; Christophe Pierrat

doi:10.1117/12.681871

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19 May 2006 Pellicle-induced aberrations and apodization in hyper-NA optical lithography

Karsten Bubke; Benjamin Alles; Eric Cotte; Martin Sczyrba; Christophe Pierrat

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Proceedings Volume 6283, Photomask and Next-Generation Lithography Mask Technology XIII; 628318 (2006) https://doi.org/10.1117/12.681871
Event: Photomask and Next Generation Lithography Mask Technology XIII, 2006, Yokohama, Japan

Abstract

In 193nm optical lithography, immersion technology will enable numerical apertures much greater than 1.0. Furthermore, polarized light is likely to be applied, enhancing the imaging properties of structures with dimensions near the resolution limit. As a result, the consequences of extreme oblique angle illumination as well as polarization effects need to be carefully evaluated for all elements of the lithographic process. This paper explores the aberrations and apodization induced by the pellicle film in hyper NA lithography. In a first step, the angle and polarization-dependent phase errors of a perfectly flat pellicle are investigated and discussed for varying thicknesses. It will be shown that for NAs greater than 1.0 the pellicle induces higher order spherical aberrations which can be in the range of today's scanner lens specifications. Also, the impact of polarizationdependent apodization will be discussed. In a second step, the analysis is extended to the case of a non-flat pellicle due to a given frame bow. Under these conditions, the phase and transmission error is not radially symmetric and, furthermore, is field dependent. It will be discussed under which conditions this effect can lead to a significant pellicle-induced CD signature over the entire image field.

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Karsten Bubke, Benjamin Alles, Eric Cotte, Martin Sczyrba, and Christophe Pierrat "Pellicle-induced aberrations and apodization in hyper-NA optical lithography", Proc. SPIE 6283, Photomask and Next-Generation Lithography Mask Technology XIII, 628318 (19 May 2006); https://doi.org/10.1117/12.681871