Určování tvaru neuniformity v tloušťce pomocí spektroskopické elipsometrie s proměnným úhlem

Determining shape of thickness non-uniformity using variable-angle spectroscopic ellipsometry

journal article in Web of Science

en

The effects of thickness non-uniformity on measured optical quantities must be often considered in the optical characterization. The effects of thickness non-uniformity can be taken into account by averaging the Mueller matrices over the distribution of local thicknesses within the measured area. The distribution of local thicknesses can be assumed in a certain form (e.g. the uniform distribution), or it can be derived on the basis of a model assuming a certain shape of thickness non-uniformity. The latter approach is especially useful for the variable-angle spectroscopic ellipsometry since it can take into account dependence on the incidence angle due to the changes in the size of the light spot. This paper presents results of the optical characterization of three polymer-like thin films highly non-uniform in thickness using variable-angle spectroscopic ellipsometry. The shapes of the thickness non-uniform films are determined on the basis of a model assuming local thicknesses given by quadratic polynomials in coordinates along the surfaces of the films. The studied areas on the films were also measured by the imaging spectroscopic reflectometry, which provides a more direct method to determine local thicknesses. The results achieved using the imaging spectroscopic reflectometry and variable-angle spectroscopic ellipsometry were then compared.

Při optické charakterizaci tenkých vrstev se často projeví vliv neuniformity v tloušťce na měření optických veličin. Tento vliv lze vzít do úvahy zprůměrováním Mullerových matic přes rozdělení lokálních tlouštěk podél měřené plochy. O tomto rozdělení lze předpokládat, že má určitou formu (např. je uniformní), nebo lze ji odvodit na základě modelu, který předpokládá určitý tvar nerovnoměrnosti tloušťky. To je vhodné zejména pro spektroskopickou elipsometrii s proměnným úhlem (VASE), protože může brát v úvahu závislost na úhlu dopadu v důsledku změn ve velikosti světelné stopy elipsometru. Článek prezentuje výsledky optické charakterizace tří polymerům podobných vrstev velmi neuniformních v tloušťce pomocí VASE. Tvar neuniformity v tloušťce je odvozen na základě modelu předpokládajícího, že lokální tloušťka je popsána kvadratickými polynomy v souřadnicích podél povrchu vrstev. Studované plochy vrstev byly také měřeny zobrazovací spektroskopickou reflektometrií (ISR), která poskytuje přímější metodu určení lokálních tlouštěk. Výsledky získané pomocí ISR a VASE byly poté srovnány.

The effects of thickness non-uniformity on measured optical quantities must be often considered in the optical characterization. The effects of thickness non-uniformity can be taken into account by averaging the Mueller matrices over the distribution of local thicknesses within the measured area. The distribution of local thicknesses can be assumed in a certain form (e.g. the uniform distribution), or it can be derived on the basis of a model assuming a certain shape of thickness non-uniformity. The latter approach is especially useful for the variable-angle spectroscopic ellipsometry since it can take into account dependence on the incidence angle due to the changes in the size of the light spot. This paper presents results of the optical characterization of three polymer-like thin films highly non-uniform in thickness using variable-angle spectroscopic ellipsometry. The shapes of the thickness non-uniform films are determined on the basis of a model assuming local thicknesses given by quadratic polynomials in coordinates along the surfaces of the films. The studied areas on the films were also measured by the imaging spectroscopic reflectometry, which provides a more direct method to determine local thicknesses. The results achieved using the imaging spectroscopic reflectometry and variable-angle spectroscopic ellipsometry were then compared.

Neuniformita v tloušťce, Elipsometrie, Zobrazovací spektroskopická reflektometrie

Thickness non-uniformity; Ellipsometry; Imaging spectroscopic reflectometry

30.12.2020

ELSEVIER

AMSTERDAM

1873-5584

534

147625

1–10

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