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Proceedings Paper

Shadowing 3D mask effects in EUV
Author(s): Eytan Barouch
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Paper Abstract

A new method to evaluate the shadowing effect of 3-dimensional mask has been developed and implemented for extreme UV technology. The method is composed of several key ingredients. The illuminator(source) is divided into very small domains to account for the partial coherence nature of the illumination employed by the microchip industry. Each sub-domain acts as an incoherent source emitting a partial vector electromagnetic field. Since the design on the mask is described on a sub- nanometer(nm) grid and the features are 20-40nm, a non-uniformed grid is essential for a manageable computation. Consequently, the space describing the mask is a mixture of momenta(kx,ky) and physical space(z-direction). The corresponding Maxwell equations are translated to the mask space and the transmitted wave of each sub illuminator is propagated through the optical system. This construction eliminates the usual use of the Kirchhoff boundary conditions which are normally used in the formation of the aerial image. Instead the integration over the source(illuminator) takes place over the propagated field into the photoresist constructing the latent image directly. Employing a previously developed techniques the latent image is translated into photoacid concentration, enabling the determination of the developed photoresist structures. By using the described methodology, a shadowing effect is detected and by the usage of a newly developed optimization-scheme of the shape of the source the shadowing effect can be minimized or even eliminated.

Paper Details

Date Published: 30 June 2012
PDF: 5 pages
Proc. SPIE 8441, Photomask and Next-Generation Lithography Mask Technology XIX, 84411L (30 June 2012); doi: 10.1117/12.964977
Show Author Affiliations
Eytan Barouch, Boston Univ. (United States)


Published in SPIE Proceedings Vol. 8441:
Photomask and Next-Generation Lithography Mask Technology XIX
Kokoro Kato, Editor(s)

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