Plasma-enhanced CVD preparation of isotopes of group IV and VI elements

19th International Summer School on Vacuum, Electron and Ion Technologies

Sennikov, P.G.^1 ; Kornev, R.A.^1

Laboratory of Plasma Chemistry, G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, Nizhny Novgorod

603950, Russia^1

关键词: Capacitively coupled;    Chemical reduction;    Emission spectrums;    Experimental conditions;    Inductively-coupled;    Isotopic and chemical purity;    Isotopic composition;    Reaction mechanism;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/700/1/012042/pdf
DOI  :  10.1088/1742-6596/700/1/012042

来源: IOP

【 摘 要 】

The plasma-chemical reduction was studied experimentally of molybdenum, sulfur and germanium fluorides with different isotopic composition by hydrogen in plasmas sustained by inductively coupled (IC) and capacitively-coupled (CC) RF discharges. The emission spectra of plasmas recorded under different experimental conditions are discussed. Reaction mechanisms are proposed. In the case of98MoF6reduction in CCP, the combined radical-atomic mechanism including intermediate MoF3resulting in bulk and powder98Mo formation was established. In the emission spectrum of the32SF6+ H2system in ICP at 0.2 Torr, only lines assigned to SiF2, SiF and F2∗originating from the decomposition of32SF6and a fast reaction of its products with the reactor's quartz walls were observed. Due to this etching process, the yield of32S was moderate. Increasing the pressure in the reactor above 1 Torr resulted in an increase of the32S yield. The mechanism of72GeF4reduction depends on the pressure and plasma type. At 0.25 Torr in ICP, a72Ge deposit was formed via the72GeF radical; however, at 3.5 Torr in CCP, the mechanism changed to a molecular one. Results of the study of the structure and the isotopic and chemical purity of isotope samples obtained are briefly presented.