Mechanism of thermal decomposition of silanes

Onischuk, A. A.; Panfilov, V. N.

doi:10.1070/rc2001v070n04abeh000603

Cited by 32 publications

(22 citation statements)

References 191 publications

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“…The signal corresponding to the molecular ion (m/z 32) is rather weak. The even weaker signal at m/z 33 and m/z 34 (not visible) are isotope peaks caused by the natural abundances of 29 Si, 30 Si and 2 H. There is good agreement between our measured mass spectrum and the mass spectrum from the literature [66] (Fig. 4a, lower pane).…”

Section: Monosilanesupporting

confidence: 72%

“…13,16,[20][21][22][23][24][25][26][27], have been conducted to broaden the understanding of the monosilane pyrolysis. It is commonly accepted that the pyrolysis occurs through a series of chemical reactions, including SiASi bond formation and hydrogen elimination, producing silanes with increasing number of Si atoms [13,20,22,23,28,29]. Additionally, 1,2-hydrogen shifts, ring opening and ring closing lead to interconversion between different isomers within each silane family [22,23,30,31].…”

Section: Pyrolysis Of Sih 4 In Solar Silicon Industrymentioning

confidence: 99%

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Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry

Wyller

Klette

Mongstad

et al. 2018

Journal of Crystal Growth

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a b s t r a c tThere is a deficit of ways to detect higher order silane isomers during silane pyrolysis. Thus, a novel instrument utilizing gas chromatography-mass spectrometry (GC-MS) for detection of higher order silanes has been developed. The instrument enables us to separate higher order silane species using gas chromatography before they are introduced to the mass spectrometer, thereby obtaining spectra of separate isomers, rather than overlaid spectra. In this contribution we describe the details of the GC-MS system. We compare our GC-separated mass spectra of mono-, di-and trisilane to mass spectra of these species available in the literature. Further, we present mass spectra of the tetrasilane isomers n-tetrasilane (n-Si 4 H 10 ), silyltrisilane (i-Si 4 H 10 ) and cyclotetrasilane (cyclo-Si 4 H 8 ) and of the pentasilane isomers n-pentasilane (n-Si 5 H 12 ), silyltetrasilane (i-Si 5 H 12 ) disilyltrisilane (neo-Si 5 H 12 ) and cyclopentasilane (cyclo-Si 5 H 10 ). Six of these mass spectra are previously unpublished. Based on the fragmentation pattern in the tetra-and pentasilane mass spectra, we are able to acquire mass spectra of silanes with up to eight silicon atoms. Finally, we apply the novel detection technique to a silane pyrolysis reactor to track the outlet concentration of higher order silanes as function of reactor temperature. We believe that the detection technique that we present here may open the door for validation of monosilane pyrolysis models, and thus constitute a roadmap for future research in this field.

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Section: Monosilanesupporting

confidence: 72%

Section: Pyrolysis Of Sih 4 In Solar Silicon Industrymentioning

confidence: 99%

Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry

Wyller

Klette

Mongstad

et al. 2018

Journal of Crystal Growth

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“…(57) Abstract: The invention concerns a gas distribution arrangement, a device for handling a chemical reaction comprising such a gas distribution arrangement and a method of providing a chemical reaction chamber with a gas. The distribution arrangement cornprises a distribution plate (16) for separating a chemical reaction chamber (14) from a gas inlet area (12) and having a first side (20) arranged to face the chemical reaction chamber and a second side(l8) arranged to face the gas inlet area and comprising a set of through holes stretching between the first and the second side, where the first side of the plate comprises a first material surrounding the holes and having a first thermal conductivity, and the plate also comprises a second material forming a base structure also surrounding the holes and having a second thermal conductivity. One known distribution pla~e is described in OS 3, 889 , 631 .…”

Section: Resultsmentioning

confidence: 99%

“…of having the gas in the inlet area 12 close to the reaction temperature is that the loss of temperature of the gas due to passing through the 10 throughholes 22 will not significantly affect the efficiency of gas chemical reaction of the gas after e xiting the throughholes 22 into the reaction chamber While the invention has been described in connection with what is presently considered to be most practical and preferred embodiments , it is to be understood that 5 the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements. reactor for silicon production , comprising a distribution plate (16) for separallng a chemical reaction chamber (14) from a gas inlet area (12) and having a first side (20) arranged to face Lhe chemical reaction chamber and a second side (18) arranged to face the gas inlet area, the 10 distribution plate comprising a set of throughholes (22) 17 . The gas distribution arrangement according to any previous claim, further comprising at least one heat diverting element (17) connected to the base structure .…”

Section: Brief Description Of the Drawingsmentioning

confidence: 99%

Production of Silicon from SiH4 in a Fluidized Bed, Operation and Results

Filtvedt

Mongstad

Holt

et al. 2013

International Journal of Chemical Reactor Engineering

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The photovoltaic industry has experienced a tremendous growth over the last years. The backbone of the technology has so far been elemental silicon. Silicon is the second most abundant element on the earth, but in order to be utilized for solar panels, it needs to be purified. This purification process is very energy intensive. Behind a finished solar module, up to 30% of the energy goes into purification depending on route, Cucchiella and D´Adamo (2012).Reducing the energy payback time of solar panels is important, and focus on silicon production is crucial, since this is one of the most energy intensive parts. The production of polysilicon involves production of metallurgical silicon from quartz and further processing into polysilicon. The most common route for the latter step is the Siemens process. In this process, chlorosilane is produced from chlorination of the metallurgical silicon. Subsequently, trichlorosilane is reduced in a decomposition process after some additional refining. The decomposition reactor itself is where the energy consumption becomes large.The silicon containing reactant starts to decompose at a temperature of typically 350 -480 °C depending on the process. However, in order to assure correct deposition, the deposition itself has to happen at temperatures as high as 1100°C for trichlorosilane, and about 650°C for monosilane. The layout of the Siemens process is simple. Electrical heating elements of silicon are distributed within a cooled dome. The heating elements are kept at typically 1100°C, while all other surfaces are kept at about 250°C. The process takes days and even weeks, depending on the process optimization, and the heat loss is therefore substantial.There is one other technology producing polysilicon to the market today, and this is the fluidized bed reactor. In a Fluidized Bed Reactor (FBR), the reactor vessel is filled with silicon particles. A gas is injected at the bottom of the reactor to fluidize the particles. Fluidizing the particles means the drag force on the individual particles is on the same scale as the weight of the particle. In this state, the bed of particles behaves like a liquid, and the flow of gas keeps the bed in continuous motion. The particles are heated to a temperature above the decomposition temperature and the reactant gas is inserted to the bed. Upon decomposition, the silicon deposit on the particles thus making them grow. After some dwell time, the particles have grown to a size suitable for extraction. The finished beads are then extracted, and new small seed particles are inserted to or produced within the bed.What complicates the picture is the decomposition of the reactant and how this influences growth. Challenges associated with FBR production of polysilicon involves dust (fines) production, unwanted depositions on surfaces other than the beads as well as inadequate quality due to porosity, amorphous inclusions and impurities.During the PhD project a state of the art fluidized bed has been designed, built and operated. This the...

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“…However, whereas suboptimal deposition due to low temperature may lead to hydrogen inclusions for silanes, they will lead to chlorine inclusions for chlorosilane based depositions [40]. This may be improved by going to higher temperatures and higher hydrogen to TCS ratios, as these will increase reverse mechanisms leading to continual chlorine removal.…”

Section: Fbrmentioning

confidence: 99%

Deposition reactors for solar grade silicon: A comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

Ramos

Filtvedt

Lindholm

et al. 2015

Journal of Crystal Growth

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Polysilicon production costs contribute approximately to 25-33% of the overall cost of the solar panels and a similar fraction of the total energy invested in their fabrication. Understanding the energy losses and the behaviour of process temperature is an essential requirement as one moves forward to design and build large scale polysilicon manufacturing plants. In this paper we present thermal models for two processes for poly production, viz., the Siemens process using trichlorosilane (TCS) as precursor and the fluid bed process using silane (monosilane, MS). We validate the models with some experimental measurements on prototype laboratory reactors relating the temperature profiles to product quality. A model sensitivity analysis is also performed, and the effects of some key parameters such as reactor wall emissivity, gas distributor temperature, etc., on temperature distribution and product quality are examined. The information presented in this paper is useful for further understanding of the strengths and weaknesses of both deposition technologies, and will help in optimal temperature profiling of these systems aiming at lowering production costs without compromising the solar cell quality.

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Mechanism of thermal decomposition of silanes

Cited by 32 publications

References 191 publications

Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry

Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry

Production of Silicon from SiH4 in a Fluidized Bed, Operation and Results

Deposition reactors for solar grade silicon: A comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

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