Reaction Mechanism of Chlorosiloxane Ring Formation from SiCl<sub>4</sub> and O<sub>2</sub>

Kumar, Anil; Homann, Thorsten; Jug, Karl

doi:10.1021/jp014235o

Cited by 6 publications

(3 citation statements)

References 50 publications

(124 reference statements)

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“…The molecular properties of interest, viz., ionization potentials and bond lengths of the present targets are adopted from the relevant literature [6,10,[27][28][29][30][31] and are listed in table 1.…”

Section: Theoretical Methodologymentioning

confidence: 99%

Electron impact ionization of plasma important SiCl_X(X= 1–4) molecules: theoretical cross sections

Kothari¹,

Pandya

Joshipura

2011

J. Phys. B: At. Mol. Opt. Phys.

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Electron impact ionization of SiCl X (X = 1-4) molecules is less studied but an important process for understanding and modelling the interactions of silicon-chlorine plasmas with different materials. The SiCl 3 radical is a major chloro-silicon species involved in the CVD (chemical vapour deposition) of silicon films from SiCl 4 /Ar microwave plasmas. We report in this paper the total ionization cross sections for electron collisions on these silicon compounds at incident energies from the ionization threshold to 2000 eV. We employ the 'complex scattering potential-ionization contribution' method and identify the relative importance of various channels, with ionization included in the cumulative inelastic scattering. New results are also presented on these exotic molecular targets. This work is significant in view of the paucity of theoretical studies on the radicals SiCl X (X = 1-3) and on SiCl 4 .

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Section: Theoretical Methodologymentioning

confidence: 99%

Electron impact ionization of plasma important SiCl_X(X= 1–4) molecules: theoretical cross sections

Kothari¹,

Pandya

Joshipura

2011

J. Phys. B: At. Mol. Opt. Phys.

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“…Since the 1990s, there have been a number of theoretical studies of the mechanism of siloxane formation. − First, Kudo and Gordon 11,12 investigated the reactions of SiHCl 3 and SiH 4 - x (OH) x with water at the Si−Cl hydrolysis step and at further condensation steps. They estimated the activation energies and found that the energy of activation at both the primary hydrolysis and activation steps can be significantly lowered by the coordination of additional water molecules to the transition structures.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of the Reaction Mechanism and Role of Water Clusters in the Gas-Phase Hydrolysis of SiCl₄

et al. 2003

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The energies and thermodynamic parameters of the elementary reactions involved in the gas-phase hydrolysis of silicon tetrachloride were studied using ab initio quantum chemical methods (up to MP4//MP2/6-311G-(2d,2p)), density functional (B3LYP/6-311++G(2d,2p)), and G2(MP2) theories. The proposed mechanism of hydrolysis consists of the formation of SiCl 4-x , chainlike and cyclic siloxane polymers [-SiCl 2 sO-] n , dichlorosilanone Cl 2 SidO, and silicic acid (HO) 2 SidO. Thermodynamic parameters were estimated, and the transition states were located for all of the elementary reactions. It was demonstrated that the experimentally observed kinetic features for the hightemperature hydrolysis are well described by a regular bimolecular reaction occurring through a four-membered cyclic transition state. In contrast, the low-temperature hydrolysis reaction cannot be described by the traditionally accepted bimolecular pathway for SisCl bond hydrolysis because of high activation barrier (E a ) 107.0 kJ/mol, ∆G q ) 142.5 kJ/mol) nor by reactions occurring through three-or four-molecular transition states proposed earlier for reactions occurring in aqueous solution. The transition states of SiCl 4 with oneand two-coordinated water molecules were located; these significantly decrease the free energy of activation ∆G q (to 121.3 and 111.5 kJ/mol, correspondingly). However, this decrease in ∆G q is not sufficient to account for the high value of the hydrolysis rate observed experimentally under low-temperature conditions.

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“…A recent theoretical study has suggested that the reaction proceeds via a chlorosiloxane ring (Cl 2 SiO) 2 . 7 Also connected with the use of SiCl 4 in CVD and CVT processes is the need to obtain this reagent in a high degree of purity. As such there is a need to develop a greater understanding of the reactions of SiCl 4 and the role of silicon oxychloridesas may be illustrated by the photochemical synthesis and determination by infrared spectroscopy of trichlorosilanol SiCl 3 OH in SiCl 4 .…”

Section: Introductionmentioning

confidence: 99%

The gas-phase reactions of SiCl4 and Si2Cl6 with CH3OH and C2H5OH: An investigation by mass spectrometry and matrix-isolation infrared spectroscopy

Goldberg

Almond

Ogden

et al. 2004

Phys. Chem. Chem. Phys.

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The gas phase reactions of SiCl 4 and Si 2 Cl 6 with CH 3 OH and C 2 H 5 OH have been investigated using both mass spectrometry and matrix isolation techniques. SiCl 4 reacts with both CH 3 OH and C 2 H 5 OH upon mixing of the vapours for times in excess of 3 h to generate the HCl-elimination products SiCl 3 OR (R ¼ CH 3 or C 2 H 5 ). The identity of these products is confirmed by deuteration experiments and by ab initio calculations at the HF/6-31G(d) level. Further products are generated when the mixture is passed through a tube heated to 750 C. Si 2 Cl 6 reacts with CH 3 OH and C 2 H 5 OH via a different mechanism in which the Si-Si bond is cleaved to yield SiCl 3 OR and HCl. Other products of the type SiCl 4Àn (OCH 3 ) n are tentatively identified by a combination of mass spectrometric and matrix isolation measurements. These latter products indicate further replacement of Cl atoms by OR groups as a result of reaction of CH 3 OH or C 2 H 5 OH with the initial product.

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Reaction Mechanism of Chlorosiloxane Ring Formation from SiCl₄ and O₂

Cited by 6 publications

References 50 publications

Electron impact ionization of plasma important SiCl_X(X= 1–4) molecules: theoretical cross sections

Electron impact ionization of plasma important SiCl_X(X= 1–4) molecules: theoretical cross sections

Theoretical Study of the Reaction Mechanism and Role of Water Clusters in the Gas-Phase Hydrolysis of SiCl₄

The gas-phase reactions of SiCl4 and Si2Cl6 with CH3OH and C2H5OH: An investigation by mass spectrometry and matrix-isolation infrared spectroscopy

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Reaction Mechanism of Chlorosiloxane Ring Formation from SiCl4 and O2

Cited by 6 publications

References 50 publications

Electron impact ionization of plasma important SiClX(X= 1–4) molecules: theoretical cross sections

Electron impact ionization of plasma important SiClX(X= 1–4) molecules: theoretical cross sections

Theoretical Study of the Reaction Mechanism and Role of Water Clusters in the Gas-Phase Hydrolysis of SiCl4

The gas-phase reactions of SiCl4 and Si2Cl6 with CH3OH and C2H5OH: An investigation by mass spectrometry and matrix-isolation infrared spectroscopy

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Reaction Mechanism of Chlorosiloxane Ring Formation from SiCl₄ and O₂

Electron impact ionization of plasma important SiCl_X(X= 1–4) molecules: theoretical cross sections

Electron impact ionization of plasma important SiCl_X(X= 1–4) molecules: theoretical cross sections

Theoretical Study of the Reaction Mechanism and Role of Water Clusters in the Gas-Phase Hydrolysis of SiCl₄