Three-dimensional rigorous simulation of EUV defective masks using modal method by Fourier expansion

Abstract

In Extreme Ultraviolet Lithography, the electromagnetic modelling of the mask allows determining the influence of the mask structure on the electromagnetic field. That makes it possible to take into account the presence of a defect modifying the multi-layer stack 1,2 . The method used throughout this paper is the MMFE (Modal Method by Fourier Expansion) also known as the RCWA (Rigorous Coupled Wave Analysis). Modal methods allow computing the electromagnetic field just above the EUV mask or the near field. Modal methods are well adapted for EUV mask simulation due to materials and structure size. The previous works performed on 2D simulation with MMFE 3 have shown the influence of a defect inside a EUV mask structure. In this article, the method is extended to address 3D structures. The printability of a spherical shaped defect is analyzed depending on the deposition process used. The influence of a 3D defect position regarding the position of a line absorber is also shown.