30 July 2002 Through-pitch correction of scattering effects in 193-nm alternating phase-shift masks
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Abstract
A methodology to study the bias and phase correction of strong phase-shifting masks is introduced. Isolated apertures are simulated to investigate the influence of aperture size, undercut etch, and quartz sidewall angle on aperture transmission. The simulations match well with experimental results that are measured with an ArF microlithography simulation microscope. For alternating apertures, electromagnetic calculations are done to solve for the diffracted fields. An analytical method is derived to deduce aperture bias and phase error from the diffracted orders. This method can be used as an easy way to optimize the cross section of the phase shifting mask. The method is demonstrated for the example of a single trench alternating phase shifting mask. A constant bias that minimizes the asymmetry and phase error without the need for an undercut etch is found. Such bias works for both the case of equal lines and spaces through pitch and constant linewidth through pitch. Because this bias is easy to design into a mask, the design and manufacturing of alternating phase shifting can be simplified.
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Martin Burkhardt, Martin Burkhardt, Ronald L. Gordon, Ronald L. Gordon, Michael S. Hibbs, Michael S. Hibbs, Timothy A. Brunner, Timothy A. Brunner, "Through-pitch correction of scattering effects in 193-nm alternating phase-shift masks", Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); doi: 10.1117/12.474584; https://doi.org/10.1117/12.474584
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