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Plasma CVD of B-C-N Thin Films Using Triethylboron in Argon-Nitrogen Plasma

preprint
submitted on 05.02.2020 and posted on 07.02.2020 by Laurent Souqui, Justinas Palisaitis, Hans Högberg, Henrik Pedersen

Amorphous boron-carbon-nitrogen (B-C-N) films with low density are potentially interesting as alternative low-dielectric-constant (low-κ) materials for future electronic devices. Such applications require deposition at temperatures below 300 °C, making plasma chemical vapor deposition (plasma CVD) a preferred deposition method. Plasma CVD of B-C-N films is today typically done with separate precursors for B, C and N or with precursors containing B–N bonds and an additional carbon precursor. We present an approach to plasma CVD of B-C-N films based on triethylboron (B(C2H5)3) a precursor with B-C bonds in an argon-nitrogen plasma. From quantitative analysis with Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA), we find that the deposition process can afford B-C-N films with a B/N ratio between 0.98 and 1.3 and B/C ratios between 3.4 and 8.6 and where the films contain between 3.6 and 7.8 at. % H and 6.6 and 20 at. % of O. The films have low density, from 0.32 to 1.6 g/cm3 as determined from cross-section scanning electron micrographs and ToF-ERDA with morphologies ranging from smooth films to separated nanowalls. Scaning transmission electron microscopy shows that C and BN does not phase seperarte in the film. The static dielectric constant κ, measured by capacitance–voltage measurements, varies with the Ar concentration in the range from 3.3 to 35 for low and high Ar concentrations, respectively. We suggest that this dependence is caused by the energetic bombardment of plasma species during film deposition.


Funding

This work was supported by the Swedish Foundation for Strategic Research (SSF) (Contract No. IS14-0027). H.P. and H.H. acknowledge financial support from the Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No. 2009-00971). Support from the Swedish research council VR-RFI (Contract 2017-00646_9) for the Accelerator based ion-technological center, and from the Swedish Foundation for Strategic Research (Contract RIF14-0053) for the tandem accelerator laboratory in Uppsala is gratefully acknowledged. The authors acknowledge the Knut and Alice Wallenberg Foundation for support of the Linköping electron microscopy laboratory.

History

Email Address of Submitting Author

henrik.pedersen@liu.se

Institution

Linkoping University

Country

Sweden

ORCID For Submitting Author

0000-0002-7171-5383

Declaration of Conflict of Interest

No conflicts to declare

Exports