Publication detail
Optical Characterization of Non-Stoichiometric Silicon Nitride Films Exhibiting Combined Defects
VOHÁNKA, J. OHLÍDAL, I. OHLÍDAL, M. ŠUSTEK, Š. ČERMÁK, M. ŠULC, V. VAŠINA, P. ŽENÍŠEK, J. FRANTA, D.
Czech title
Optická charakterizace nestechiometrických vrstev nitridu křemíku vykazujících kombinované defekty
English title
Optical Characterization of Non-Stoichiometric Silicon Nitride Films Exhibiting Combined Defects
Type
journal article in Web of Science
Language
en
Original abstract
The study was devoted to optical characterization of non-stoichiometric silicon nitride films prepared by reactive magnetron sputtering in argon-nitrogen atmosphere onto cold (unheated) substrates. It was found that these films exhibit the combination of three defects: optical inhomogeneity (refractive index profile across the films), uniaxial anisotropy with the optical axis perpendicular to the boundaries and random roughness of the upper boundaries. The influence of the uniaxial anisotropy was included into the corresponding formulae of the optical quantities using the matrix formalism and the approximation of the inhomogeneous layer by a multilayer system consisting of large number thin homogeneous layers. The random roughness was described using the scalar diffraction theory. The processing of the experimental data was performed using the multi-sample modification of the least-squares method, in which experimental data of several samples differing in thickness were processed simultaneously. The dielectric response of the silicon nitride films was modeled using the modification of the universal dispersion model, which takes into account absorption processes corresponding to valence-to-conduction band electron transitions, excitonic effects and Urbach tail. The spectroscopic reflectometric and ellipsometric measurements were supplemented by measuring the uniformity of the samples using imaging spectroscopic reflectometry of the samples using imaging spectroscopic reflectometry.
Czech abstract
Je studována optická charakterizace nestechiometrických vrstev nitridu křemíku připravených reaktivním magnetronovým naprašováním na chladné (nezahřívané) podložky v argonové – dusíkově atmosféře. Bylo zjištěno, že tyto vrstvy vykazují kombinaci tří defektů: optické nehomogenity (profil indexu lomu napříč vrstvami), jednoosé anizotropie s optickou osou kolmou k rozhraním a náhodné drsnosti horních rozhraní. Vliv jednoosé anizotropie byl zahrnut do odpovídajících vzorců pro optické veličiny užitím maticového formalizmu a aproximací nehomogenní vrstvy mnohavrstevným systémem velkého počtu tenkých homogenních vrstev. Náhodná drsnost byla popsána v rámci skalární teorie difrakce. Zpracování experimentálních dat bylo provedeno užitím mnohavzorkové modifikace metody nejmenších čtverců, ve které byla experimentální data několika vzorků lišících se v tloušťce zpracovávána současně. Dielektrická odezva studovaných vrstev byla modelována pomocí modifikace univerzálního disperzního modelu, který bere v úvahu absorpční procesy odpovídající elektronovým přechodům mezi valenčním a vodivostním pásem, exitačním procesům a Urbachovu konci. Spektroskopická reflektometrická a elipsometrická měření byla doplněna měřením uniformity vzorků pomocí zobrazovací spektroskopické reflektometrie.
English abstract
The study was devoted to optical characterization of non-stoichiometric silicon nitride films prepared by reactive magnetron sputtering in argon-nitrogen atmosphere onto cold (unheated) substrates. It was found that these films exhibit the combination of three defects: optical inhomogeneity (refractive index profile across the films), uniaxial anisotropy with the optical axis perpendicular to the boundaries and random roughness of the upper boundaries. The influence of the uniaxial anisotropy was included into the corresponding formulae of the optical quantities using the matrix formalism and the approximation of the inhomogeneous layer by a multilayer system consisting of large number thin homogeneous layers. The random roughness was described using the scalar diffraction theory. The processing of the experimental data was performed using the multi-sample modification of the least-squares method, in which experimental data of several samples differing in thickness were processed simultaneously. The dielectric response of the silicon nitride films was modeled using the modification of the universal dispersion model, which takes into account absorption processes corresponding to valence-to-conduction band electron transitions, excitonic effects and Urbach tail. The spectroscopic reflectometric and ellipsometric measurements were supplemented by measuring the uniformity of the samples using imaging spectroscopic reflectometry of the samples using imaging spectroscopic reflectometry.
Keywords in Czech
nitrid křemíku; optická charakterizace; elipsometrie; nehomogenní vrstvy; optická anizotropie
Keywords in English
silicon nitride; optical characterization; ellipsometry; inhomogeneous films; optical anisotropy
Released
28.06.2019
Publisher
MDPI
Location
ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND
ISSN
2079-6412
Volume
˙9
Number
7
Pages from–to
1–21
Pages count
21
BIBTEX
@article{BUT157633,
author="Jíří {Vohánka} and Ivan {Ohlídal} and Miloslav {Ohlídal} and Štěpán {Šustek} and Martin {Čermák} and Václav {Šulc} and Petr {Vašina} and Jaroslav {Ženíšek} and Daniel {Franta},
title="Optical Characterization of Non-Stoichiometric Silicon Nitride Films Exhibiting Combined Defects",
year="2019",
volume="˙9",
number="7",
month="June",
pages="1--21",
publisher="MDPI",
address="ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND",
issn="2079-6412"
}