Abstract: A granular fluidized bed reactor (FBR) for production of high purity silicon is described. The FBR uses a draft tube to promote internal circulation while minimizing voids in the fluidized bed, one significant cause of dust formation. The FBR design has geometries to minimize reactive gas concentration within the draft tube and imposes a desirable circulation pattern in operation. A portion of the FBR wall above a reactive zone provides heat input to maximize deposition on silicon beads while minimizing wall deposition. The FBR is made of carbon composite, ceramic, and graphite materials in a design to minimize contamination and enable silicon deposits to be melted out.

Abstract: The invention relates generally to heaters and methods of using the heaters. In certain embodiments, a heater includes a pressure shell having a cylindrical heating cavity, an annular heat shield disposed within the cylindrical heating cavity, and at least one heating element disposed within an interior volume of the annular heat shield. In another embodiment, a method of preparing a trichlorosilane includes introducing a reactant stream comprising silicon tetrachloride into a heater, passing electrical current through a heating element to heat the reactant stream, and introducing the heated reactant stream into a reactor.

Abstract: The systems and method of the invention involve hydrochlorination by providing feed streams with suitable reaction conditions through reactant stream conditioning systems and components. The conditioning systems facilitate vaporization of silicon tetrachloride in gaseous hydrogen to produce a reactant stream comprising hydrogen that is saturated with silicon tetrachloride. Saturation can be effected without the use of superheated steam or hot oil by utilizing saturated steam that is less than about 15 bar. The saturated reactant stream can be further heated to reaction conditions that effect conversion to trichlorosilane.

Abstract: The invention relates to an improved process to manufacture TCS in a polysilicon plant based upon combining a high temperature FBR process reacting metallurgical grade silicon, hydrogen, and silicon tetrachloride (STC) to make trichlorosilane (TCS) and a high temperature thermal converter to hydrogenate STC to TCS and hydrogen chloride.

Abstract: A counter current heat exchanger amenable to fabrication from monolithic materials and particularly useful in corrosive and high temperature environments is described. The heat exchanger uses multiple series of holes bored axially through a monolithic material. Axial holes are bored in adjacent flow paths arranged in closely spaced concentric rings. In operation, counter current flow and heat transfer occurs between multiple adjacent axial flow paths. The heat exchanger design is scaleable over a wide range and particularly useful in reactors for the hydrogenation of halosilanes also using cylindrical heating elements. The design enables a small overall reactor size for a given capacity.

Abstract: The invention relates to apparatus and associated methods for conversion of silicon tetrachloride (STC) to trichlorosilane (TCS). The converter features a relatively thin annular heating zone surrounding a reaction chamber. Within the annular heating zone is a heating element that has an annular conformation about the reaction chamber. The design allows high convective heat transfer, which facilitates the use of lower heating element surface temperatures, prolonging the life of the equipment, reducing capital cost by allowing use of a smaller reactor, and greatly improving heating efficiency. A heat exchanger with a plurality of heat exchanger blocks provides further efficiency.

Abstract: Systems and methods for removing boron-containing contaminants from a composition comprising trichlorosilane to form a purified product comprising trichlorosilane are disclosed. Purification columns and devices, having various locations of inlet and outlet ports, are fluidly connected to each other in order to remove various types of boron species and other impurities present in TCS.

Abstract: A granular fluidized bed reactor (FBR) for production of high purity silicon is described. The FBR uses a draft tube to promote internal circulation while minimizing voids in the fluidized bed, one significant cause of dust formation. The FBR design has geometries to minimize reactive gas concentration within the draft tube and imposes a desirable circulation pattern in operation. A portion of the FBR wall above a reactive zone provides heat input to maximize deposition on silicon beads while minimizing wall deposition. The FBR is made of carbon composite, ceramic, and graphite materials in a design to minimize contamination and enable silicon deposits to be melted out.

Abstract: The invention relates to an improved process to manufacture TCS in a polysilicon plant based upon combining a high temperature FBR process reacting metallurgical grade silicon, hydrogen, and silicon tetrachloride (STC) to make trichlorosilane (TCS) and a high temperature thermal converter to hydrogenate STC to TCS and hydrogen chloride.

Abstract: A counter current heat exchanger amenable to fabrication from monolithic materials and particularly useful in corrosive and high temperature environments is described. The heat exchanger uses multiple series of holes bored axially through a monolithic material. Axial holes are bored in adjacent flow paths arranged in closely spaced concentric rings. In operation, counter current flow and heat transfer occurs between multiple adjacent axial flow paths. The heat exchanger design is scaleable over a wide range and particularly useful in reactors for the hydrogenation of halosilanes also using cylindrical heating elements. The design enables a small overall reactor size for a given capacity.

Abstract: Systems and methods for removing boron-containing contaminants from a composition comprising trichlorosilane to form a purified product comprising trichlorosilane are disclosed. Purification columns and devices, having various locations of inlet and outlet ports, are fluidly connected to each other in order to remove various types of boron species and other impurities present in TCS.

Abstract: The invention relates to apparatus and associated methods for conversion of silicon tetrachloride (STC) to trichlorosilane (TCS). The converter features a relatively thin annular heating zone surrounding a reaction chamber. Within the annular heating zone is a heating element that has an annular conformation about the reaction chamber. The design allows high convective heat transfer, which facilitates the use of lower heating element surface temperatures, prolonging the life of the equipment, reducing capital cost by allowing use of a smaller reactor, and greatly improving heating efficiency. A heat exchanger with a plurality of heat exchanger blocks provides further efficiency.

Abstract: The present invention is directed to systems and methods of synthesizing trichlorosilane. The disclosed systems and methods can involve increasing the concentration of the solids in the slurry to recover or separate the volatilized metal salts and reduce the obstructions created by the solidification of the metal salts in downstream operations of the during trichlorosilane synthesis. Rather than heating to raise the temperature to vaporize chlorosilane compounds, and subsequently condensing the volatilized chlorosilane compounds, the present invention can involve increasing the solids concentration in the slurry stream by utilizing a non-condensable gas, such as hydrogen, to volatilize the chlorosilane components, which can consequently promote evaporative conditions that can reduce the slurry temperature. The lower slurry temperature results in a lower volatility of the metal salts, which reduces the likelihood of carryover to downstream unit operations.

Abstract: The systems and method of the invention involve hydrochlorination by providing feed streams with suitable reaction conditions through reactant stream conditioning systems and components. The conditioning systems facilitate vaporization of silicon tetrachloride in gaseous hydrogen to produce a reactant stream comprising hydrogen that is saturated with silicon tetrachloride. Saturation can be effected without the use of superheated steam or hot oil by utilizing saturated steam that is less than about 15 bar. The saturated reactant stream can be further heated to reaction conditions that effect conversion to trichlorosilane.

Abstract: A method for making a higher silane from a lower silane comprises heating a lower silane containing stream without exposing it to temperatures more than 20° C. more than the maximum temperature of a first reaction temperature range. The heated lower silane containing stream is introduced into a first reaction zone and allowed to react. The method further comprises mixing a first gaseous mixture from the first reaction zone with a higher silane containing stream and introducing the mixed streams into a second reaction zone operating within a second reaction temperature range. A second gaseous mixture exiting the second reaction zone is separated into various streams. One stream containing unreacted lower silanes is recycled to an earlier heating step and first reaction zone. The higher silane containing stream is mixed with the first gaseous mixture. Average residence time is low to prevent decomposition and formation of undesired silane byproducts.

Abstract: The invention relates generally to heaters and methods of using the heaters. In certain embodiments, a heater includes a pressure shell having a cylindrical heating cavity, an annular heat shield disposed within the cylindrical heating cavity, and at least one heating element disposed within an interior volume of the annular heat shield. In another embodiment, a method of preparing a trichlorosilane includes introducing a reactant stream comprising silicon tetrachloride into a heater, passing electrical current through a heating element to heat the reactant stream, and introducing the heated reactant stream into a reactor.

Abstract: The present invention is directed to systems and methods of synthesizing trichlorosilane. The disclosed systems and methods can involve increasing the concentration of the solids in the slurry to recover or separate the volatilized metal salts and reduce the obstructions created by the solidification of the metal salts in downstream operations of the during trichlorosilane synthesis. Rather than heating to raise the temperature to vaporize chlorosilane compounds, and subsequently condensing the volatilized chlorosilane compounds, the present invention can involve increasing the solids concentration in the slurry stream by utilizing a non-condensable gas, such as hydrogen, to volatilize the chlorosilane components, which can consequently promote evaporative conditions that can reduce the slurry temperature. The lower slurry temperature results in a lower volatility of the metal salts, which reduces the likelihood of carryover to downstream unit operations.

Abstract: A method for making a higher silane from a lower silane comprises heating a lower silane containing stream without exposing it to temperatures more than 20° C. more than the maximum temperature of a first reaction temperature range. The heated lower silane containing stream is introduced into a first reaction zone and allowed to react. Unreacted lower silanes are recycled to the earlier heating step. Preferably the average residence time is low to prevent decomposition and formation of undesired silane byproducts. A method for making a higher than higher silane from a lower silane comprises mixing a first gaseous mixture from the first reaction zone with a higher silane containing stream and introducing the mixed streams into a second reaction zone operating within a second reaction temperature range. A second gaseous mixture exiting the second reaction zone is separated into various streams. One stream containing unreacted lower silanes is recycled to an earlier heating step and first reaction zone.