Квазиоптическое масштабное моделирование влияния локализованных дефектов поверхности металлов на данные оптической эллипсометрии

Abstract

Ellipsometry is a highly sensitive, non-contact, non-destructive method for studying surfaces and interphase boundaries, based on the study of changes in the polarization state of the probe electromagnetic wave asa result of its interaction with the boundary between the media. A special problem in the analysis of the ellipsometric data are surface defects, which include roughness, island films, regular relief, some localized defects. To date, there are no adequate models describing the effect of localized surface defects on results of ellipsometrical experiments. Previously, it has been suggestedthat localized defects under certain conditions may not affect the ellipsometric data. The purpose of this work is to test this hypothesis by conducting systematic studies of the influence of defects in the form of parallelepipeds of various sizes on the ellipsometric data. Scale modeling of influence of defects typical for surface subjected to radiation sputtering on ellipsometric experiment results in the optical range has been performed using developed terahertz ellip-someter that operates at wavelength λ =2.2 mm (0.14 THz). Such a large operating wavelength allowed to form on the surface defects of a given shape and size and to investigate their impact on the ellipsometric parameters. A description of the ellipsometer, and the results of systematic studies of the influence of various defects on the surface of the material with strong absorption data ellipsometry are presented. It is first experimentally proved that localized defects of comparable size to the wavelength can be "invisible" for ellipsometry.