イベント

千現地区 研究本館8階 中セミナー室
Sengen Main Bldg. 8F Middle Seminar Room

Prof. Ding Zejun (中国科学技術大学)

Application of Monte Carlo Simulation Methods in Surface Electron Spectroscopy and Scanning Electron Microscopy

Monte Carlo simulation method, based on random sampling of electron scattering events in specimen, has been widely used to study beam-sample interaction in electron beam related techniques for material science research. Typical application fields include surface electron spectroscopy and scanning electron microscopy. In this talk, I will report several aspects of our recent studies for the development of the methods and their applications: 1. Aimed at the linewidth measurement and critical dimension (CD) metrology by CD-SEM the classical Monte Carlo method is extended to treat the sample with complex geometry by a constructive solid geometry modeling for a 3D structure with smooth surface and a finite element triangle mesh modeling for a rough/smooth surface. A simulation algorithm is developed for study of charging problem in insulating materials with complex morphology under irradiation of an electron beam. 2. We have further developed a reverse Monte Carlo method for extraction of optical constants from reflection electron energy loss spectroscopy (REELS) spectra for removing surface excitation effect and multiple scattering effect from experimental spectra. The method combines the conventional Monte Carlo simulation of REELS spectrum and Markov chain Monte Carlo sampling of oscillator parameters in order to have a quick converged fitting to experimental spectra. 3. Furthermore, to study coherent electron scattering in a crystalline solid we have developed a new Monte Carlo method, the quantum trajectory Monte Carlo method; the method combines Bohmian quantum trajectory method for treating electron elastic scattering and diffraction in a crystal with a conventional Monte Carlo sampling of inelastic scattering events along quantum trajectory path; leading to the simulation of atomic resolution secondary electron image.