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On the Plasma Chemistry of an RF Discharge Containing Aluminium Tri‐Isopropoxide Studied by FTIR Spectroscopy
Author(s) -
Hübner M.,
Fröhlich M.,
Tawidian H.,
Mikikian M.,
Röpcke J.,
Kersten H.
Publication year - 2014
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201310065
Subject(s) - fourier transform infrared spectroscopy , analytical chemistry (journal) , molecule , dissociation (chemistry) , fragmentation (computing) , aluminium , spectroscopy , plasma , infrared spectroscopy , infrared , chemistry , materials science , physics , organic chemistry , quantum mechanics , computer science , optics , operating system
In Ar and Ar/N 2 radio frequency (RF) discharges with admixtures of aluminium tri‐isopropoxide (ATI) the fragmentation of this metal‐organic precursor was studied by means of Fourier Transform Infrared (FTIR) spectroscopy using an optical long path cell providing an optical length of l = 17.2 m. The experiments were performed in an asymmetric capacitively coupled process plasma at a frequency of f = 13.56 MHz and at pres‐sure values in the range of p = 1–10.5 Pa. The discharge power was chosen between P = 10–100 W. Using FTIR spectroscopy the evolution of the concentrations of ATI and of six stable molecules, CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , CO and HCN, was monitored under flowing conditions at gas flows of Φ total = 0.5–14.5 sccm in the discharge. The concentrations of the reaction products were measured tobe between 2 x 10 12 molecules cm –3 as e.g. found for C 2 H 4 and C 2 H 6 , and 5 x 10 13 molecules cm –3 , as e.g. in the case of CO. In the plasma a complete dissociation of the precursor ATI was found at a power value of about P = 80 W independent on the admixture of Ar or N 2 . The fragmentation efficiency (F E ) of the reaction products which originate from the ATI molecules ranges between 0.2 and 4 x 10 16 molecules J –1 while the fragmentation rate (F R ) reached up to 2.5 x 10 18 molecules s –1 . The multi component detection ability of the spectrometer served to analyse the carbon balance of the by‐product formation. For all experiments, the carbon balance never exceeded 25%. Therefore, in the plasmas the majority of the provided carbon is most likely deposited at the reactor walls or forms dust particles or higher molecular C x H y . The conversion efficiencies (C E ) of the produced molecular species ranges between 0.1 x 10 15 molecules J –1 for C 2 H 4 and 5 x 10 15 molecules J –1 for C 2 H 6 depending on the discharge conditions of the RF plasma. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)