Abstract: 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.

Abstract: 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.

Abstract: 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—except for the filament rods close to the reactor wall—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.

Abstract: A rod having a length of 0.5 m to 4 m and having a diameter of 25 mm to 220 mm, comprising a high-purity alloy composed of 0.1 to 50 mol % germanium and 99.9 to 50 mol % silicon, the alloy having been deposited on a thin silicon rod or on a thin germanium-alloyed silicon rod, the deposited alloy having a polycrystalline structure.

Abstract: 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 >20 ?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.

Abstract: Rod-type, polycrystalline silicon having a rod diameter of >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.

Abstract: Rod-type, polycrystalline silicon having a rod diameter of >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.

Abstract: 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>20 ?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.

Abstract: The invention relates to a process for deposition of polycrystalline silicon, including introduction of a reaction gas containing a silicon-containing component and hydrogen into a reactor, as a result of which polycrystalline silicon is deposited in the form of rods, which includes passing into the reactor, after the deposition has ended, a gas which attacks silicon or silicon compounds which flows around the polycrystalline rods and an inner reactor wall in order to dissolve silicon-containing particles which are formed in the course of deposition and adhere on the inner reactor wall or on the polycrystalline silicon rods before the polycrystalline silicon rods are removed from the reactor.

Abstract: Rod-type, polycrystalline silicon having a rod diameter of >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.

Abstract: 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—except for the filament rods close to the reactor wall—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.

Abstract: 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).

Abstract: A device for protecting electrode holders in CVD reactors includes an electrode suitable for accommodating a filament rod on an electrode holder which includes an electrically conductive material and is installed in a recess of a bottom plate, wherein an intermediate space between an electrode holder and a bottom plate is sealed by means of a sealing material, and the sealing material is protected by a protective body which is made up of one or more parts and is arranged in a ring-like manner around the electrodes, and the height of the protective body increases at least in sections in the direction of the electrode holder.

Abstract: 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).

Abstract: 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.

Abstract: Rod-type, polycrystalline silicon having a rod diameter of >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.

Abstract: A rod having a length of 0.5 m to 4 m and having a diameter of 25 mm to 220 mm, comprising a high-purity alloy composed of 0.1 to 50 mol % germanium and 99.9 to 50 mol % silicon, the alloy having been deposited on a thin silicon rod or on a thin germanium-alloyed silicon rod, the deposited alloy having a polycrystalline structure.

Abstract: 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.