- Laser induced dielectric breakdown for synthesis of chlorofluorosilanes
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Tetrafluorosilane (SF4) and tetrachlorosilane (SiCl4) plasmas have been widely used as a source of either F or Cl for etching silicon or as a source of silicon for deposition of Si-based materials. Using different combinations of F and Cl in molecules of chlorofluorosilane SiFxCly adds additional flexibility in realization of these processes. Direct synthesis of SiFxCl4-x (x = 1, 2, 3) from SiF4 and SiCl4 is thermodynamically forbidden under standard conditions. This restriction is removed in low-temperature plasmas studied in this work: a laser induced dielectric breakdown (LIDB) plasma and steady-state inductively-coupled plasma (ICP). The plasmas differ in many respects including energy content, temperature, and electron density that lead to different ionization/excitation states of plasma species, which are observed from plasma optical emission spectra. IR spectroscopy and mass-spectrometry confirm the formation of three chlorofluorosilanes, SiF3Cl, SiF2Cl2, and SiFCl3 that constitute ~60 % in products of LIDB plasma and split 50/50 between SiF3Cl, SiFCl3 and SiF2Cl2. Experimental observations are verified by equilibrium static calculations via the minimization of Gibbs free energy and by dynamic calculations via the chemical-hydrodynamic plasma model of a spherically expanding plasma plume. The both types of calculations qualitatively agree with the results of spectroscopic analysis and reproduce dominant presence of SiF2Cl2 as the temperature of the gas approaches the room temperature.
- Ermakov, A. A.,Gornushkin, I. B.,Kornev, R. A.,Polyakov, V. S.,Sennikov, P. G.,Shkrunin, V. E.
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- Infrared photoreaction of 2-chloroethyltrifluorosilane
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Infrared laser dissociation of 2-chloroethyltrifluorosilane has been studied in light of silicon isotopes separation. The reaction occurs via beta-elimination mechanism to yield ethylene and chlorotrifluorosilane as products. The dissociation has a relatively low energy barrier what was confirmed by high-level quantum chemical calculations. High enrichment of 30Si isotope was demonstrated.
- Dementyev, Petr S.,Nizovtsev, Anton S.,Chesnokov, Evgenii N.
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- PROCESSES FOR PRODUCING HYDROHALOCARBON AND HALOCARBON COMPOUNDS USING SILICON TETRAFLUORIDE
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Methods and systems for producing hydrohalocarbon and/or halocarbon compounds with an inorganic fluoride (e.g., silicon tetrafluoride (SiF4)) are disclosed herein.
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Page/Page column 5-6
(2009/04/24)
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- Conversion of alkyltrifluoroborates into alkyldichloroboranes with tetrachlorosilane in coordinating solvents
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Organotrifluoroborate salts are converted rapidly by tetrachlorosilane in nucleophilic solvents such as THF or acetonitrile into organodichloroboranes coordinated with the solvent (see scheme). This reaction completes a sequence from alkylboronic esters via the trifluoroborate salts to reactive alkyldichloroboranes under mild conditions.
- Kim, Byung Ju,Matteson, Donald S.
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p. 3056 - 3058
(2007/10/03)
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- Preparation of mixed-halogen halo-silanes
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The preparation of halosilanes having mixed-halogen substituents is described comprising providing an aryl-halo-silane having one more first halogens and one or more aryl groups, and substituting one or more of said aryl groups of said aryl-halo-silane with a second halogen having an atomic number greater than that of said first halogen.
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- Low temperature fluorination of some non-metals and non-metal compounds with fluorine
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Low temperature fluorination with elemental fluorine of elemental phosphorus, sulphur, silicon, amorphous carbon and phosphorus trichloride, phosphorus pentoxide, triphenylphosphine, hexafluorodisilane, hexachlorodisilane, hexabromodisilane, tetrasulphur tetranitride, sulphur dioxide, thionyl chloride and sulphuryl chloride has been carried out in freon-11 medium.The corresponding fluoro compounds have been isolated in near quanititative yields, purified by low temperature fractional condensation and characterised by IR spectroscopy and elemental analysis.
- Padma, D K,Kalbandkeri, R G,Suresh, B S,Bhat, V Subrahmanya
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p. 172 - 176
(2007/10/02)
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- Synthesis and Properties of Trimethyl(trifluorosilyl)stannane
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Trimethyltin hydride reacts with SiF3SiF3 or SiF3SiF2H to give the new compound SnMe3(SiF3) in 75-80 percent yield.No reaction was observed between SnMe3H and SiF3SiH3.Hydrogen-deuterium exchange was observed between tin and silicon during the course of deuterium-labelling experiments.Dimethylstannylene (SnMe2) was implicated as an intermediate by trapping experiments in the thermolysis of SnMe3(SiF3).
- D'Errico, John,Sharp, Kenneth G.
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p. 1879 - 1882
(2007/10/02)
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- Selective and sequential reduction of polyhalosilanes with alkyltin hydrides
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The reactions between alkyltin hydrides and a variety of polyhalo- and mixed halosilanes have been investigated. For SiCl4 and SiCl3H, the reductions proceed in a stepwise manner to yield the monoreduced species as the major products. The reduction of SiBr4 occurs much faster to yield a mixture of SiBr3H and SiH4, or, in the vapor phase, SiBr3H as the sole product. SiF3X (X = Br, Cl) is converted into SiF3H, with no further reduction of SiF3H observed upon addition of a second equivalent of alkyltin hydride. SiF2HX compounds (X = Br, Cl) are obtained from SiF2X2 and are converted into SiF2H2 with excess Me3SnH. Redistribution becomes competitive with reduction in reactions between Me3SnH and SiFBr3, leading to mixtures of SiH4, SiF2H2, and SiF3H. The major products in the reaction between SiCl2Br2 and Me3SnH are SiCl3H and SiH4 (no SiCl2H2 was observed). Several probable intermediates were independently synthesized and allowed to react with Me3SnH. Together with deuterium labeling experiments, these reactions shed light on the mechanisms involved in these systems. In particular, the reactions appear not to proceed via free radicals.
- D'Errico, John J.,Sharp, Kenneth G.
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p. 2177 - 2180
(2008/10/08)
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- Reaction of Silicon Difluoride with Halogens: a Reinvestigation
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Reactions of SiF2 with halogens have been reinvestigated by both co-condensation and gas-phase methods.The co-condensation method yields a number of fluorohalogenosilanes including mono-, di-, and higher silane derivatives.These compounds contain SiF, SiF2, and SiF3 units.The reactivity towards SiF2 decreases from chlorine through bromine to iodine.While chlorine and bromine give rise to a number of fluorohalogenosilanes, iodine yields only the monosilane derivatives.In contrast, the gas-phase reaction do not progress to any appreciable extent.The products have been characterized by mass spectrometry and 19F and 29Si n.m.r. spectroscopy.Many have been identified for the first time.
- Suresh, Bettadapura S.,Thompson, James Charlton
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p. 1123 - 1126
(2007/10/02)
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