Open AccessCharacterization of nanoscale gratings by spectroscopic reflectometry in the extreme ultraviolet with a stand-alone setup
Author(s) -
Lukas Bahrenberg,
Serhiy Danylyuk,
Sven Glabisch,
Moein Ghafoori,
Sophia Schröder,
Sascha Brose,
Jochen Stollenwerk,
Peter Loosen
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.396001
Subject(s) - reflectometry , optics , grating , materials science , extreme ultraviolet , extreme ultraviolet lithography , wavelength , rigorous coupled wave analysis , nanoscopic scale , characterization (materials science) , optoelectronics , diffraction grating , laser , physics , nanotechnology , time domain , computer science , computer vision
The authors present a study on the dimensional characterization of nanoscale line gratings by spectroscopic reflectometry in the extreme ultraviolet spectral range (5 nm to 20 nm wavelength). The investigated grating parameters include the line height, the line width, the sidewall angle and corner radii. The study demonstrates that the utilization of shorter wavelengths in state-of-the-art optical scatterometry provides a high sensitivity with respect to the geometrical dimensions of nanoscale gratings. Measurable contrasts are demonstrated for dimensional variations in the sub-percent regime, down to one tenth of a nanometer and one tenth of a degree in absolute terms. In an experimental validation of the method, it is shown that reflectance curves can be obtained in a stand-alone setup using the broadband emission of a discharge produced plasma as the source of EUV radiation, demonstrating the potential scalability of the method for industrial uses. Simulated reflectance curves are fit to the experimental curves by variation of the grating parameters using rigorous electromagnetic modeling. The obtained grating parameters are cross-checked by a scanning electron microscopy analysis.