Patent ID: 8399072

Claim:
A process for producing a polycrystalline silicon rod comprising the steps of: providing a silicon rod production apparatus, comprising: 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 individual isolation jacket, wherein each individual isolation jacket provides gas distribution nozzles distributed around each filament/slim-rod assembly for feeding a reactant gas stream to the reaction chamber; 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 direct current power supply wherein the power supply supplies less than about 26,000 volts; wherein the apparatus does not include a heating finger; preheating the reaction chamber to a temperature at which the silicon filaments become more conductive by circulating a heat transfer fluid in the heat transfer system; heating the silicon filaments to a silicon deposition temperature by applying an electric current from the power supply; feeding the reactant gas stream to the reaction chamber; decomposing at least a part of the reactant gas stream to form silicon; and depositing silicon on the silicon filaments to produce a polycrystalline silicon rod.