Impact Of Line Edge Roughness Patterns On The Reconstructed Critical Dimensions In Scatterometry

摘要

In angular resolved scatterometry, the measured diffraction intensities are effected by structure roughness. We investigate this impact by rigorous finite element method (FEM) calculations for an EUV photomask with periodic line-space structures. Repeated calculations for large FEM domains with stochastically chosen line and space widths are applied. Complementary simulations based on 2D-Fourier transforms for samples of binary 2D gratings confirm the FEM results. The edge roughness of the binary 2D gratings are modelled by a power spectrum density (PSD) function providing a more realistic approach for line roughness.