1 July 1991 Laser alignment modeling using rigorous numerical simulations
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This paper describes a three-dimensional computer modeling technique for alignment system simulation, and some example calculations. The technique has been developed to address issues of alignment and overlay accuracy for future generation VLSI technology. The analytical basis is a general finite element electromagnetic wave propagation code, EMFlex, that rigorously simulates light scattering from the 3-D alignment mark. Using the Nikon Laser Step Alignment (LSA) system as a model instrument, the overlay error and signal shape are simulated. Examples of an idealized asymmetric metal mark are studied. Preliminary results suggest that the rigorous simulations are substantially different from the one-dimensional Fresnel approximations that have been used previously.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gregory L. Wojcik, Gregory L. Wojcik, David K. Vaughan, David K. Vaughan, John Mould, John Mould, Francisco A. Leon, Francisco A. Leon, Qi-De Qian, Qi-De Qian, Michael A. Lutz, Michael A. Lutz, "Laser alignment modeling using rigorous numerical simulations", Proc. SPIE 1463, Optical/Laser Microlithography IV, (1 July 1991); doi: 10.1117/12.44789; https://doi.org/10.1117/12.44789

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