Abstract: A hydrogen recycle process and system for use with chemical vapor deposition (CVD) Siemens type processes is provided. The process results in substantially complete or complete hydrogen utilization and substantially contamination-free or contamination-free hydrogen.

Abstract: An improved process and apparatus for uniform gas distribution in chemical vapor deposition (CVD) Siemens type processes is provided. The process comprises introduction of a silicon-bearing gas tangentially to and uniformly along the length of a growing silicon rod in a CVD reactor, resulting in uniform deposition of polysilicon along the rod. The apparatus comprises an improved gas nozzle design and arrangement along the length of the rod, promoting uniform deposition of polysilicon.

Abstract: The present invention relates to a monosilane (SiH4) and hydrogen recycle process/system for chemical vapor deposition (CVD) of monosilane-based CVD polysilicon. In particular, the present invention relates to the substantially complete silane utilization and unconverted (from the reactor) contamination-free complete silane and hydrogen recycle process of producing polysilicon chunk materials via the decomposition of gaseous silane precursors.

Abstract: A process for producing silicon rods including providing a reactor vessel containing at least one reaction chamber surrounded by a jacket, wherein a pre-heating fluid is circulated in the jacket; one or more electrode assemblies extending into the reaction chamber wherein each electrode assembly comprises a gas inlet, one or more heat transfer fluid inlets/outlets, at least one pair of silicon filaments, the filaments connected to each other at their upper ends with a silicon bridge to form a filament/slim rod assembly, each filament/slim rod assembly enclosed in an isolation jacket; a source of a silicon-bearing gas connected to the interior of the vessel for supplying the gas into the reaction chamber to produce a reaction and to deposit polycrystalline silicon on the filament by chemical vapor deposition thereby producing a rod of polycrystalline silicon; a heat transfer system that is connected to the jacketed reaction chamber that supplies heat transfer fluid to preheat the reaction chamber; and a power

Abstract: The present invention relates to a monosilane (SiH4) and hydrogen recycle process/system for chemical vapor deposition (CVD) of monosilane-based CVD polysilicon. In particular, the present invention relates to the substantially complete silane utilization and unconverted (from the reactor) contamination-free complete silane and hydrogen recycle process of producing polysilicon chunk materials via the decomposition of gaseous silane precursors.

Abstract: A process of producing silicon tetrafluoride from fluoride containing feedstocks. The process calcines the fluoride containing feedstock and a silica containing feedstock before reacting the mixture with sulfuric acid to produce silicon tetrafluoride. The silicon tetrafluoride is scrubbed with sulfuric acid. Excess sulfuric acid is recycled to the process. The process demonstrates an economic and environmentally friendly way to produce high quality silicon tetrafluoride.

Abstract: A hydrogen recycle process and system for use with chemical vapor deposition (CVD) Siemens type processes is provided. The process results in substantially complete or complete hydrogen utilization and substantially contamination-free or contamination-free hydrogen.

Abstract: An improved process and apparatus for uniform gas distribution in chemical vapor deposition (CVD) Siemens type processes is provided. The process comprises introduction of a silicon-bearing gas tangentially to and uniformly along the length of a growing silicon rod in a CVD reactor, resulting in uniform deposition of polysilicon along the rod. The apparatus comprises an improved gas nozzle design and arrangement along the length of the rod, promoting uniform deposition of polysilicon.

Abstract: Embodiments of the invention provide a system and process for recovering useful compounds from a byproduct composition produced in a silicon tetrafluoride production process.

Abstract: Embodiments of the invention provide a system and process for recovering useful compounds from a byproduct composition produced in a silicon tetrafluoride production process.

Abstract: A process for producing silicon rods including providing a reactor vessel containing at least one reaction chamber surrounded by a jacket, wherein a pre-heating fluid is circulated in the jacket; one or more electrode assemblies extending into the reaction chamber wherein each electrode assembly comprises a gas inlet, one or more heat transfer fluid inlets/outlets, at least one pair of silicon filaments, the filaments connected to each other at their upper ends with a silicon bridge to form a filament/slim rod assembly, each filament/slim rod assembly enclosed in an isolation jacket; a source of a silicon-bearing gas connected to the interior of the vessel for supplying the gas into the reaction chamber to produce a reaction and to deposit polycrystalline silicon on the filament by chemical vapor deposition thereby producing a rod of polycrystalline silicon; a heat transfer system that is connected to the jacketed reaction chamber that supplies heat transfer fluid to preheat the reaction chamber; and a power

Abstract: A process of producing silicon tetrafluoride from fluoride containing feedstocks. The process calcines the fluoride containing feedstock and a silica containing feedstock before reacting the mixture with sulfuric acid to produce silicon tetrafluoride. The silicon tetrafluoride is scrubbed with sulfuric acid. Excess sulfuric acid is recycled to the process. The process demonstrates an economic and environmentally friendly way to produce high quality silicon tetrafluoride.

Abstract: This invention relates to a process for obtaining dry sodium aluminum hydride from a slurry containing the production products from a sodium aluminum hydride plant.