1 January 2008 Vectorial imaging of deep subwavelength mask features in high NA ArF lithography
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As silicon processes scale toward the 45-nm node using conventional 0.25-magnification, the feature sizes on the photomask are below the ArF (193.3 nm) laser wavelength. At these scales, traditional scalar and paraxial approximations used for optical image modeling are no longer valid. Thick-mask and vector-based rigorous models are equired to account for mask topographic effects and large incident angles at the reticle plane in ultra-high numerical aperture (NA) systems. Experimental depolarization measurements through advanced optical reticles at 193 nm are compared to rigorous finite-difference timedomain vector-based electromagnetic simulations. The validated simulation model is extended to explore the impact of polarization purity, mask absorber profile, mask film properties, and Fresnel effects through the pellicle on the imaging process window and requirements for optical proximity correction (OPC) in immersion imaging. The model has shown that line-end pullback has a strong correlation with mask shadowing under TE-polarized off-axis illumination (OAI).
© (2008) Society of Photo-Optical Instrumentation Engineers (SPIE)
Wen-Hao Cheng, Wen-Hao Cheng, Jeff Farnsworth, Jeff Farnsworth, } "Vectorial imaging of deep subwavelength mask features in high NA ArF lithography," Journal of Micro/Nanolithography, MEMS, and MOEMS 7(1), 013001 (1 January 2008). https://doi.org/10.1117/1.2841718 . Submission:

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