Untersuchung des Widerstandsverhaltens dünner Metallschichten (Ta, Nb) und Nb/Si-Vielfachschichten

Sajovec, F.

Book/Report

FZJ-2018-04434

Untersuchung des Widerstandsverhaltens dünner Metallschichten (Ta, Nb) und Nb/Si-Vielfachschichten

Sajovec, F. (Corresponding author)FZJ*

1993
Forschungszentrum Jülich GmbH Zentralbibliothek Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek Verlag, Berichte des Forschungszentrums Jülich 2806, 88 p. (1993)

Please use a persistent id in citations: http://hdl.handle.net/2128/19423

Report No.: Juel-2806

Abstract: In $\textit{situ}$ resistance measurements during the growth of ion beam sputter deposited tantalum films have been employed to elucidate the conditions necessary for the formation of either the b.c.c. ($\alpha$-Ta) or the tetragonal ($\beta$-Ta) structure. Tantalum films condense at room temperature onto sputter-cleaned fused silica substrates as the $\beta$ phase with resistivities $\rho$ in the range 200-220 $\mu \Omega \cdot$ cm. $\alpha$-Ta films with $\rho$ between 40 and 55 $\mu \Omega \cdot$ cm can be prepared if the films are deposited on the top of thin (more than 3 nm) niobium underlayers. The niobium underlayer thickness is very critical with respect to the nucleation process of tantalum. When it is less than 3 nm, tantalum films consisting of mixtures of $\alpha$-Ta and $\beta$-Ta result. This is because niobium on fused silica nucleates first in a structure differing from the common b.c.c. structure. This phase cannot promote the nucleation of pure $\alpha$-Ta. It converts to b.c.c.-Nb if the layer thickness exceeds 3 nm. The experimental results provide the basis for a discussion of the relationsbetween the structural changes and the resistance of the growing films. To evaluate the electrical properties of the films the well-known Fuchs-Namba relation was applied. In situ resistance-isotherms of Nb/Si multilayers were performed at temperatures between 250-300° C, in a hydrogen and argon atmosphere, in order tostudy the kinetics of nucleation and growth of NbSi$_{2}$. The results were discussed using Avrarni's theory of phase transformations. The characteristics of the transformation are not affected by the gas atmosphere but by the transformation time. Under hydrogen the transformation time is approximately twenty timeslonger then the time under argon.

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