Rigorous electromagnetic simulation of EUV masks: influence of the absorber properties

In this paper, we present the first application of the rigorous coupled wave analysis (RCWA) to EUV lithography. The Fourier modal method (also known as RCWA) is one of the simplest methods to deal with diffraction by gratings. It is used here to model the case of reflective EUV masks. We show the computation of the electromagnetic fields within and in the near vicinity of the multilayer EUV mask for periodic features in both TE and TM polarisation. The very time efficient method permits easy study of the influence of the different mask parameters and the influence of the main absorber properties. Material, thickness and profile of the absorber patterns are considered. Current status of the tool only considers 2D structures. By nature, the model is better suited to periodic features.