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2017
Conference Paper
Titel
Characterization of pellicle membranes by lab-based spectroscopic reflectance and transmittance measurements in the extreme ultraviolet
Abstract
In this paper, studies on the characterization of pellicle membranes with a lab-based spectroscopic reflectometer operated in the extreme ultraviolet (EUV) spectral range from 8.7 nm to 15 nm are presented. This includes the actinic wavelength of EUV lithography at 13.5 nm for high volume manufacturing as well as its neighboring spectral bands. The tool can perform spectroscopic measurements of reflectance under adjustable incidence angles of grazing illumination, ranging from 5° to 12°. Additionally, spectroscopic measurements of transmittance under normal incidence for thin membranes ⪅ 100 nm can be performed. By acquisition of a data set of transmittance and reflectance values, membranes are characterized with respect to their optical constants and their dimensional parameters such as thickness and roughness by means of reconstruction. From reconstructed optical constants further properties such as density and stoichiometry can be derived.