Impact of mask topography and multilayer stack on high NA imaging of EUV masks

We study the impact of mask topography effects on imaging with high NA. We show that with the current mask technology, it is possible to obtain reasonable imaging results up to 0.32 NA, however, for higher NA, the reticle design needs to be optimized in order to ensure proper imaging. We examine the influence of the multilayer and the effects of the finite absorber height on the imaging with high NA optics and devise measures which have to be taken into consideration in order to guarantee proper imaging at high NA.

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