Evaluation of stray light and quantitative analysis of its impact on lithography

Young-Chang Kim; Peter De Bisschop; Geert Vandenberghe

doi:10.1117/1.2076727

1 October 2005 Evaluation of stray light and quantitative analysis of its impact on lithography

Young-Chang Kim, Peter De Bisschop, Geert Vandenberghe

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 4, Issue 4, 043002 (October 2005). https://doi.org/10.1117/1.2076727

Abstract

It has been proposed that the impact of stray light (scattered light or flare) in lithographic exposure tools can be mathematically described by the use of a point spread function of scattering (PSF_sc). We present an experimental verification of this model as follows. First, we determined the PSF_sc at multiple positions in the exposure slit from experimental disappearing-pad-test data. It is found that a PSF_sc based on the fractal model fits these data very well. Next, we used an aerial-image simulator to quantitatively predict the impact of the fitted PSF_sc on the critical dimension (CD), for line-space (L/S) patterns with varying mask Cr coverage from light field to dark field. A dedicated mask was built to provide L/S patterns with the different Cr coverage, at the same slit positions where the stray-light measurements were done. Finally, we compared the predictions of the stray-light impact on CD with the CD measured from wafers printed with this mask. This comparison yielded good agreement, which further confirms the validity of the PSF_sc approach. We also experimentally investigated the impact of lens contamination on the PSF_sc and propose a double-sloped fractal-based PSF_sc to describe situations such as this.

©(2005) Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation Download Citation

Young-Chang Kim, Peter De Bisschop, and Geert Vandenberghe "Evaluation of stray light and quantitative analysis of its impact on lithography," Journal of Micro/Nanolithography, MEMS, and MOEMS 4(4), 043002 (1 October 2005). https://doi.org/10.1117/1.2076727

Published: 1 October 2005

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