Wacker Chemie Ag

Mikhail Sofin

Heinz Kraus

Reiner Pech

Erich Dornberger

Laszlo Fabry

Barbara Mueller

Hans-Christof Freiheit

Elmar Monz

An economic process for producing high quality finely divided silicon dioxide from mixtures comprising economical silicon compounds without operational disturbances is characterized by using as an Si source mixture of at least two silicon compounds, at least one being carbon-containing and at least one being carbon-free, supplying a fuel gas and an oxygen-containing source, the molar C/Si ratio of this mixture being between 10/BET and 35/BET, and the molar H/Cl ratio of this mixture being between 0.45+(BET/600) and 0.95+(BET/600), with BET being the specific surface area of the pyrogenic silicon dioxide under production, introducing this mixture as the main flow into a reaction space and igniting and reacting it, and isolating the resulting solid.

Method for producing highly dispersed silicon dioxide

The invention relates to an apparatus for deposition of polycrystalline silicon, including a reactor chamber with a reactor wall, at least 20 filament rods and gas inlet orifices for reaction gas in the reactor chamber, wherein each filament rod&#x2014;except for the filament rods close to the reactor wall&#x2014;has, at a distance of 150 to 450 mm, three further adjacent filament rods and one to three adjacent gas inlet orifices. The invention further relates to a process for depositing polycrystalline silicon on filament rods in such an apparatus, the gas inlet orifices are used to introduce a silicon-containing gas into the reactor chamber and the filament rods are heated to a temperature at which silicon is deposited thereon.

Apparatus for deposition of polycrystalline silicon comprising uniformly spaced filament rods and gas inlet orifices, and process for deposition of polycrystalline silicon using same

Polycrystalline silicon rods produced by the Siemens process produce a higher yield of CZ crystals when the process parameters are modified in a second stage of deposition such that an outer layer of larger crystallites having a mean swize &#x3e;20 &#x3bc;m is produced. Harvesting of these polycrystalline rods and conventional rods by enclosing them in a plastic bag or sheath prior to removal from the reactor also surprisingly increase the yield of CZ crystals grown from a melt containing the sheathed rods.

Polycrystalline silicon rod and method for producing polysilicon

Rod-type, polycrystalline silicon having a rod diameter of &#x3e;100 mm are obtained by deposition of silicon-containing gas according to the Siemens method, wherein the Si rods are brought into contact with hydrogen at the end of the deposition process during cooling in the reactor, and the cooled Si rods obtained have in perpendicular cross section cracks and/or radial stresses having a defined size.

Rod-type polysilicon having improved breaking properties

The present invention relates to an electrode composed of carbon having at least two different zones, wherein an outer zone (A) forms the base of the electrode and carries one or more inner zones, wherein the innermost zone (B) projects from the zone (A) at the top and has a lower specific thermal conductivity than zone (A).

Graphite electrode

The invention relates to a polysilicon rod for FZ applications obtainable by deposition of high-purity silicon from a silicon-containing reaction gas, which has been thermally decomposed or reduced by hydrogen, on a filament rod. The polysilicon rod contains, surrounding the filament rod, an inner zone having but few needle crystals, small in size, an outer zone having a relatively small amount of larger needle crystals, and a smooth transition zone between the inner and outer zones. The polysilicon rods are obtained in high yield and can be refined in one pass in an FZ process.

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Burghausen, Germany

Mikhail Sofin