Silicon deposition reactor apparatus

A heated silicon deposition reactor system comprising:

• a plurality of silicon beads;
• a vessel having a wall which defines a chamber that contains the beads, defines a fluidizing inlet for the injection of a gas to fluidize the beads, the chamber having at least two zones including (a) an inlet zone that contains the fluidizing inlet and that is configured to contain beads in a submerged spouted bed when gas is being injected through the fluidizing inlet, and (b) an upper zone that communicates with and is located above the inlet zone to receive gas moving upwardly from the inlet zone and that is sized and shaped to contain beads in a bubbling fluidized bed;
• a heat source for heating the contents of the vessel;
• a layer of silicon formed on at least a portion of the interior surface of the wall;
• and
• a slip coating between the interior surface of the wall and the layer of silicon to inhibit adherence of the wall to the layer of silicon, the slip coating being a powder having a melting point in Kelvin that is more than twice the temperature, also in Kelvin, of the layer of silicon during operation of the reactor system.

A heated silicon deposition reactor system comprising:

• a plurality of silicon beads;
• a vessel having a wall which defines a chamber that contains the beads, defines a fluidizing inlet for the injection of a gas to fluidize the beads, the chamber having at least two zones including (a) an inlet zone that contains the fluidizing inlet and that is configured to contain beads in a submerged spouted bed when gas is being injected through the fluidizing inlet, and (b) an upper zone that communicates with and is located above the inlet zone to receive gas moving upwardly from the inlet zone and that is sized and shaped to contain beads in a bubbling fluidized bed;
• a shroud surrounding the vessel to define an annular space between the shroud and the vessel;
• and
• a gas circulation system adapted to flow gas through the space and thereby divert and capture any external contamination flowing to the vessel and any gas that escapes from the vessel.

A heated silicon deposition reactor system comprising:

• a plurality of silicon beads;
• a vessel having a wall which defines a chamber that contains the beads, defines a fluidizing inlet for the injection of a gas to fluidize the beads, the chamber having at least two zones including (a) an inlet zone that contains the fluidizing inlet and that is configured to contain beads in a submerged spouted bed when gas is being injected through the fluidizing inlet, and (b) an upper zone that communicates with and is located above the inlet zone to receive gas moving upwardly from the inlet zone and that is sized and shaped to contain beads in a bubbling fluidized bed;
• an inner gas delivery tube that defines a gas inlet passageway in communication with the fluidizing inlet;
• an outer gas delivery tube that concentrically surrounds the inner gas delivery tube and that defines an annular space between the inner and outer tubes, the annular space being in communication with the inlet zone via an annular gas inlet at a location adjacent the fluidizing inlet;
• and
• a source of a halogen-containing gas in communication with the annular space such that the halogen-containing gas is introduced to the inlet zone via the annular space and inlet so that the gases entering the chamber via the inlets mix and react exothermically at the inlets to provide sufficient energy to heat beads in the jet.

A heated silicon deposition reactor system comprising:

• a plurality of silicon beads;
• a source of a silicon-bearing gas selected from the group consisting of silane compounds, halogenated silane compounds, and mixtures thereof;
• a vessel having a wall with an interior surface which is at least partially covered by a layer of a high purity silicon-containing material,
• the wall defining (a) a chamber that contains the beads, (b) a fluidizing inlet for the injection of the silicon-bearing gas to fluidize the beads, (c) an outlet for the removal of beads from the chamber, (d) an inlet for injecting a halogen-containing gas into the chamber to react with and convert any silicon powder and unreacted silicon-bearing gas in the chamber into halogenated species and to inhibit the deposition of silicon or silicon halide polymer on surfaces downstream of the reactor vessel, and (e) an inlet, which may be the same as or different than at least one of the other inlets, for injecting a nonsilicon-bearing diluent gas,
• the chamber having at least three zones including (a) an inlet zone that contains the fluidizing inlet and that is configured to contain beads in a submerged spouted bed when gas is being injected through the inlet, (b) a tapered zone that communicates with and is located above the inlet zone to receive gas moving upwardly from the inlet zone and that is sized and shaped to contain beads in a bubbling fluidized bed, at least a portion of the tapered zone being tapered so that the velocity of the gas decreases as the gas goes upwardly through the tapered zone and the beads are classified by size with the largest beads moving to the bottom of the vessel, the beads in the tapered zone being at a spacing and temperature such that the bed of beads in the tapered zone acts as a granular filtration device to trap silicon powder that may enter the tapered zone, and (c) a reservoir zone which communicates with and is located above the tapered zone, which reservoir zone is substantially cylindrical and has a sufficient length and cross-sectional area that beads are maintained in the reservoir zone in a well-mixed bubbling fluidized bed for 1 to 24 hours, the beads in the reservoir zone being at a spacing and temperature such that the bed of beads in the reservoir zone acts as a granular filtration device to trap silicon powder that may enter the reservoir zone,
• the fluidizing inlet being sized and positioned to deliver a silicon-bearing gas into the inlet zone as a fluidizing jet of sufficient velocity to circulate the beads inside the vessel and cause beads to impact each other such that grinding of beads occurs in the inlet zone and beads of reduced size are formed to serve as seeds for additional silicon deposition, and
• the vessel wall and fluidizing jet being sized and shaped (a) to circulate a fraction of any fine silicon particles formed in the inlet zone into the fluidizing jet so that the fine particles are increased in average size by heterogeneous silicon deposition and so that homogeneous nucleation is suppressed and (b) to perform at least a portion of the silicon deposition at conditions selected such that seed particles are inherently oriented in the position of maximum drag relative to the gas flow at the bottom of the reactor, which position is indicated by a particle Reynolds number range of 5.5 to 200, in order to enhance the sphericity of the product particles,
• a heat source to hold beads in the inlet, tapered, and reservoir zones at a temperature of 700.degree. C. to 1200.degree. C. to reduce the hydrogen content of the beads and promote polycrystalline structure in the beads;
• a slip coating on the interior surface of the layer of high purity silicon-containing material to inhibit adherence of silicon deposits to the layer, the slip coating being a powder having a melting point in Kelvin that is more than twice the temperature, also in Kelvin, of the layer of the silicon-containing material during operation of the reactor system;
• a gas delivery tube that defines a gas inlet passageway in communication with the fluidizing inlet;
• at least one outlet tube that concentrically surrounds the gas delivery tube such that an outlet passageway is defined between the tubes, the outlet passageway being in communication with the chamber to receive silicon beads exiting from the chamber, the inlet passageway and outlet passageway being in thermal communication so that heat can pass from beads exiting the chamber to gas in the inlet passageway, the amount of heat transferred being sufficiently small that the temperature inside the inlet tube remains below the temperature at which substantial deposition of silicon occurs;
• at a location above the fluidizing inlet, at least one supplemental inlet to produce a supplemental jet of gas positioned to increase the frequency of bead impacts and provide additional grinding;
• a shroud surrounding the vessel to define an annular space between the shroud and the vessel, the space being in thermal communication with the chamber of the vessel such that heat is removed from the chamber by transfer to gas in the space;
• and
• a gas circulation system adapted to flow gas through the space and thereby divert and capture any external contamination flowing to the vessel and any gas that escapes from the vessel.

A heated silicon deposition reactor system comprising:

• a plurality of silicon beads;
• a source of a silicon-bearing gas;
• and
• a vessel having a wall which defines a chamber that contains the beads and defines a fluidizing inlet suitable for the injection of the silicon-bearing gas to fluidize the beads, the vessel wall and fluidizing inlet being sized and positioned to deliver the silicon-bearing gas as a single upwardly-directed fluidizing jet in the chamber, the jet being of sufficient velocity to circulate the beads in a submerged spouted bed in the chamber and cause beads to impact each other such that grinding of beads occurs and beads of reduced size are formed to serve as seeds for additional silicon deposition.

A heated silicon deposition reactor system comprising:

• a plurality of silicon beads;
• a vessel having a wall which defines a chamber that contains the beads and defines a fluidizing inlet for the injection of a gas to fluidize the beads;
• a gas delivery tube which defines a gas inlet passageway that is in communication with the fluidizing inlet;
• and
• a radiant energy source that is oriented to direct radiant energy into the chamber via the gas delivery tube.

A heated silicon deposition reactor system comprising:

• a plurality of silicon beads;
• and
• a vessel having a wall which defines a chamber that contains the beads, a first portion of the wall defining an inlet zone and a fluidizing inlet suitable for the injection of a silicon-bearing gas to provide an upwardly-directed fluidizing jet in the inlet zone to fluidize the beads, a second portion of the wall defining a supplemental inlet configured for the injection of a gas at an elevation above the inlet zone to increase the frequency of bead impacts and thereby to form beads of reduced size to serve as seed beads on which silicon is deposited;
• and
• a source of the silicon-bearing gas, the source being operable to supply the gas to the fluidizing inlet at a velocity sufficient to form the upwardly-directed fluidizing jet.