It is well known that shrinking k1 factors and increasing MEEF are making it more difficult to print contact holes with acceptable latitude and low defectivity. Given the decreasing process latitude this implies, choosing elements of the lithography process independently is becoming less and less of an option. Instead all elements of the lithography process need to be chosen so that a production-worthy process can be rapidly developed. The large number of options available for building a process further complicates the optimization problem. In this study, simulation results are used to explore the tradeoffs between illumination options and reticle substrate choice as applied to contact hole printing. Relative defectivity levels are presented from logic test circuits for selected cases of illumination and reticle type. These selected cases show that what improves defectivity also improves the Normalized Image Log-Slope (NILS). As it has been previously shown that NILS is already an excellent image quality metric NILS improvement will be used as the basis of the work presented in this paper. Extensive simulations will be used to determine the best choice of illumination and mask type to maximize NILS and by implication minimize defect density.

Date Published: 26 June 2003
PDF: 7 pages
Proc. SPIE 5040, Optical Microlithography XVI, (26 June 2003); doi: 10.1117/12.485419

Published in SPIE Proceedings Vol. 5040:
Optical Microlithography XVI
Anthony Yen, Editor(s)