The role of Mo/Si reflective coatings in the imaging performance of an extreme-ultraviolet projection lithography system under polychromatic illumination has been theoretically examined. Using a thin-film computer model, we have explored various multilayer design criteria. Optimum operating conditions, leading to the maximum system transmittance, were found for a tuned multilayer system operating at λ = 12.7 nm. In this configuration, Mo/Si coatings have been shown to be nondetrimental to the imaging performance of our system with the introduction of only minor modifications to the propagating wave front, which can be adequately described by a simple tilt and defocus term.
© 1998 Optical Society of America
[Optical Society of America ]
N. J. Duddles, "Effects of Mo/Si Multilayer Coatings on the Imaging Characteristics of an Extreme-Ultraviolet Lithography System," Appl. Opt. 37, 3533-3538 (1998)