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Proceedings Paper

Dependence of mask topography effects on pattern variation under hyper-NA lithography
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Paper Abstract

The purpose of this work was to identify the specific effects of mask topography by analyzing in the Fourier domain. Our focus patterns extend from a simple contact hole (CH) with a fixed pitch and bias to ones that have a variety of different pitches and hole sizes. We also attempt to predict phases and amplitudes of diffraction on the pupil plane without a rigorous mask topography approximated model. Intensities of CH patterns are simulated using three mask models. We had determined that there are serious differences among the three mask models concerning the contrast of the intensity and the qualitative interpretation of the trend of contrast varies according to pitch and hole sizes. The mask topography effects can be classified into waveguide and shadowing effects simply by using the diffraction decomposition diagram. We clarify how much and when the mask topography influences imaging under hyper-NA lithography by the diagram. From 1D near-field phase distribution, it is clarified that phase distribution has also been decided by the MoSi width between holes so that waveguide effects are not only from hole but also from MoSi area. It has been determined that the influence of the real 3D structures of the mask under the hyper-NA condition cannot be disregarded. However, use of the rigorous EMF calculation costs much more and requires more time than using a non-EMF calculation. We have also clarified the mechanism of 3D mask effects based on the amplitude and the phase of the diffraction light in the Fourier-domain diagram and examined whether the 3D mask effects can be predicted by thin mask approximation (TMA) and found that once we have values of amplitude and phase of the 0th and the 1st diffraction in TMA, it will be possible to predict the values of the other pitch and the other hole size.

Paper Details

Date Published: 19 May 2008
PDF: 11 pages
Proc. SPIE 7028, Photomask and Next-Generation Lithography Mask Technology XV, 70283K (19 May 2008); doi: 10.1117/12.793127
Show Author Affiliations
Akiko Mimotogi, Toshiba Corp. (Japan)
Masamitsu Itoh, Toshiba Corp. (Japan)
Shoji Mimotogi, Toshiba Corp. (Japan)
Kazuya Sato, Toshiba Corp. (Japan)
Takashi Sato, Toshiba Corp. (Japan)
Satoshi Tanaka, Toshiba Corp. (Japan)
Soichi Inoue, Toshiba Corp. (Japan)


Published in SPIE Proceedings Vol. 7028:
Photomask and Next-Generation Lithography Mask Technology XV
Toshiyuki Horiuchi, Editor(s)

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