Unstructured tetrahedric meshes for the description of complex three-dimensional sample geometries in Monte Carlo simulation of scanning electron microscopy images for metrology applications

Extraction of roughness parameters at nanometer scale by Monte Carlo simulation of Critical Dimension Scanning Electron Microscopy

“…Complex sample geometries are usually described by an unstructured mesh up to 2,000,000 tetrahedra. Thanks to a dedicated voxelization strategy [6], the calculation time required by MC tracking in densely meshed structures is typically just a factor of two larger than in geometries using basic bodies. This makes possible to calculate linescans and images of large-size 3D models at high resolution within minutes, or few hours and to compile dense model-based libraries as shown in Section 3.1.…”

“…IES has been especially designed to accept complex sample geometries with Line Edge Roughness (LER) and to work within a commercial TCAD environment [4]. The physics considered in IES to simulate the electron-probe interactions has been presented in previous works [5,6] and recently extended to dielectrics. Special attention has been paid to the calculation time.…”

“…Due to the limitations of existing MC simulators, the rendering of the LER by CD-SEM has been investigated for pseudo-3D structures only, where the statistical fluctuations of the critical dimensions only happen in the horizontal plane, but not in along the z-axis [8,9]. Thanks to the recent advances in MC simulation for SEM [5,6], it became feasible to simulate realistic 3D geometries generated by TCAD simulation, which can account for texture variations in all three-space directions.…”