Hydrogen Reduction of MoF 6 and Molybdenum Carbide Formation in RF Inductively Coupled Low-Pressure Discharge: Experimen
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Hydrogen Reduction of MoF6 and Molybdenum Carbide Formation in RF Inductively Coupled Low‑Pressure Discharge: Experiment and Equilibrium Thermodynamics Consideration P. G. Sennikov1 · I. B. Gornushkin2 · R. A. Kornev1 · V. V. Nazarov3 · V. S. Polyakov1 · V. E. Shkrunin1 Received: 28 May 2020 / Accepted: 2 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The physical plasma parameters, temperature and electron number density, are studied in the RF-IC (RF inductively coupled) discharge at a reduced pressure of 3 Torr in mixtures 2 and CH4. The emission spectra of mixtures are investigated. It is of MoF6 with Ar, H shown that in the presence of argon, the concentration of free electrons in plasma and dissociation rate of MoF6 increase. A main role of molecular hydrogen is the generation of atomic hydrogen that binds atomic fluorine and leads to the formation of gaseous and solid products. Exhaust gas mixtures exiting the reactor are analyzed by mass spectrometry. It is shown that for all cases, the conversion of M oF6 into reaction products is close to 100%. 2 A thermodynamic analysis of the equilibrium composition of M oF6 systems with Ar, H and CH4 was carried out and the obtained results are in good agreement with experimentally observed composition of the solid and gas phases. Analysis of solid deposits from mixture MoF6/H2/Ar revealed the presence of molybdenum powder and large amount of amorphous MoFx. The deposit obtained from mixtures with methane, MoF6/H2/Ar/CH4, contained crystalline molybdenum carbide, Mo3C2. Keywords RF ICP discharge · Reduction of M oF6 · Thermodynamic · Molybdenum · Molybdenum carbide
* R. A. Kornev [email protected] 1
G. G. Devyatykh Institute of Chemistry of High-Purity Substances of RAS, 49 Tropinin Str, Nizhny Novgorod, Russia 603951
2
BAM Federal Institute for Materials Research and Testing, Richard‑Willstätter‑Strasse 11, 12489 Berlin, Germany
3
Institute of Applied Physics of RAS, 46 Ulyanov Str, Nizhny Novgorod, Russia 603951
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Plasma Chemistry and Plasma Processing
Introduction Molybdenum hexafluoride is one of eighteen hexafluorides of elements identified to date. Four of them belong to p-elements (SF6, SeF6, TeF6 and little studied PoF6), the rest belong to d and f-elements. Common properties are the low melting and boiling points and comparatively high volatility under normal conditions [1]. The first three are gases; others are liquids with vapor pressures of tens and hundreds of Torr under normal conditions. Molybdenum hexafluoride, MoF6, (tmelt = 17.4 °C, tboil = 35 °C, p = 361 Torr at 15 °C) and its analogue from VI-th Group W F6 (tmelt = 2.0 °C, tboil = 17.5 °C, p = 698 Torr at 15 °C) are the most volatile hexafluorides that makes possible to using them as efficient precursors in chemical vapor deposition (CVD) reactions. Hexafluorides began to attract attention from the middle of the last century due to the fact that some of them are obtained and used at var
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