Method for purifying metallurgical silicon for solar cells

A method for forming high quality silicon material for photovoltaic devices, the method comprising:

• transferring a raw silicon material in a crucible having an interior region, the crucible being provided within a vessel, the crucible being made of a quartz material, the quartz material being capable of withstanding a temperature of at least 1400° C.,
• subjecting the raw silicon material in the crucible to thermal energy to cause the raw silicon material to be melted into a liquid state, the melted material having an exposed region bounded by the interior region of the crucible;
• subjecting an exposed inner region of the melted material to an energy source comprising an arc heater configured above the exposed region and spaced by a gap between the exposed region and a muzzle region of the arc heater to cause formation of determined temperature profile within a vicinity of an inner region of the exposed melted material while maintaining outer regions of the melted material at a temperature below a melting point of the quartz material of the crucible;
• removing one or more impurities from the melted material to form a higher purity silicon material in the crucible;
• providing chemicals and gases required for purification and high-pressure damped gas mixtures through an independent injecting device, the independent injecting device having a chemical and gas supply tube and a high-pressure gas supply tube, the chemicals and gases required for purification being provided through the chemical and gas supply tube and the high-pressure damped gas mixtures being provided through the high-pressure gas supply tube;
• outputting an inert gas through a nozzle region to cause a dimple region within a vicinity of the center region of the melted material;
• and
• providing a cover gas to maintain the melted material within the crucible;
• wherein the nozzle region comprises a plurality of nozzles and the inert gas comprises an argon gas characterized by a flow rate suitable to form the dimple region comprising a plurality of recessed regions.

A method for forming high quality silicon material for photovoltaic devices, the method comprising:

• transferring a raw silicon material in a crucible having an interior region, the crucible being provided within a vessel, the crucible being made of a quartz material, the quartz material being capable of withstanding a temperature of at least 1400° C.;
• subjecting the raw silicon material in the crucible to thermal energy to cause the raw silicon material to be melted into a liquid state, the melted material having an exposed region bounded by the interior region of the crucible;
• subjecting an exposed inner region of the melted material to an energy source comprising an arc heater configured above the exposed region and spaced by a gap between the exposed region and a muzzle region of the arc heater to cause formation of determined temperature profile within a vicinity of an inner region of the exposed melted material while maintaining outer regions of the melted material at a temperature below a melting point of the quartz material of the crucible;
• providing plasma, gases and chemicals required for purifying in a high-speed jet flow to a surface of the silicon melt through an independent injecting device, the independent injecting device having a chemical and gas supply tube and a high pressure gas supply tube;
• raising the crucible via a crucible manipulating device within the vessel to keep a constant level of a liquid surface and to maintain heating of the silicon material at the solidus-liquidus interface;
• removing one or more impurities from the melted material to form a higher purity silicon material in the crucible;
• outputting an inert gas through a nozzle region to cause a dimple region within a vicinity of the center region of the melted material;
• and
• guiding hot gas rising from the surface of the silicon melt through a guiding element configured to cause a portion of evaporated melted material to return to the melted material.

A method for forming high quality silicon material for photovoltaic devices, the method comprising:

• transferring a raw silicon material in a crucible having an interior region, the crucible being provided within a vessel, the crucible being made of a quartz material, the quartz material being capable of withstanding a temperature of at least 1400° C.,
• subjecting the raw silicon material in the crucible to thermal energy to cause the raw silicon material to be melted into a liquid state, the melted material having an exposed region bounded by the interior region of the crucible;
• subjecting an exposed inner region of the melted material to an energy source comprising an arc heater configured above the exposed region and spaced by a gap between the exposed region and a muzzle region of the arc heater to cause formation of determined temperature profile within a vicinity of an inner region of the exposed melted material while maintaining outer regions of the melted material at a temperature below a melting point of the quartz material of the crucible;
• providing plasma, gases and chemicals required for purifying in a high-speed jet flow to the surface of the silicon melt through an independent injecting device, the independent injecting device having a chemical and gas supply tube and a high pressure gas supply tube;
• raising the crucible via a crucible manipulating device within the vessel to keep a constant level of the liquid surface and to maintain heating of the silicon material at the solidus-liquidus interface;
• removing one or more impurities from the melted material to form a higher purity silicon material in the crucible;
• outputting an inert gas through a nozzle region to cause a dimple region within a vicinity of the center region of the melted material;
• and
• transporting the crucible through the crucible manipulating device in cooperation with a crucible transporting device and a crucible conveyor belt at the end of the silicon purification process.

A method for forming high quality silicon material for photovoltaic devices, the method comprising:

• transferring a raw silicon material in a crucible having an interior region, the crucible being provided within a vessel, the crucible being made of a quartz material, the quartz material being capable of withstanding a temperature of at least 1400° C.,
• subjecting the raw silicon material in the crucible to thermal energy to cause the raw silicon material to be melted into a liquid state, the melted material having an exposed region bounded by the interior region of the crucible;
• subjecting an exposed inner region of the melted material to an energy source comprising an arc heater configured above the exposed region and spaced by a gap between the exposed region and a muzzle region of the arc heater to cause formation of determined temperature profile within a vicinity of an inner region of the exposed melted material while maintaining outer regions of the melted material at a temperature below a melting point of the quartz material of the crucible;
• providing plasma, gases and chemicals required for purifying in a high-speed jet flow to the surface of the silicon melt through an independent injecting device, the independent injecting device having a chemical and gas supply tube and a high pressure gas supply tube;
• raising the crucible via a crucible manipulating device within the vessel to keep a constant level of the liquid surface and to maintain heating of the silicon material at the solidus-liquidus interface;
• removing one or more impurities from the melted material to form a higher purity silicon material in the crucible;
• and
• outputting an inert gas through a nozzle region to cause a dimple region within a vicinity of the center region of the melted material,
• wherein the nozzle region comprises a plurality of nozzles and the inert gas comprises an argon gas characterized by a flow rate suitable to form the dimple region comprising a plurality of recessed regions.

A method for forming high quality silicon material for photovoltaic devices, the method comprising:

• transferring a raw silicon material in a crucible having an interior region, the crucible being provided within a vessel, the crucible being made of a quartz material, the quartz material being capable of withstanding a temperature of at least 1400° C.;
• subjecting the raw silicon material in the crucible to thermal energy to cause the raw silicon material to be melted into a liquid state, the melted material having an exposed region bounded by the interior region of the crucible;
• subjecting an exposed inner region of the melted material to an energy source comprising two or more arc heaters symmetrically configured above the exposed region and spaced by a gap between the exposed region and a muzzle region of each of the two or more arc heaters to cause formation of a determined temperature profile within a vicinity of an inner region of the exposed melted material while maintaining outer regions of the melted material at a temperature below a melting point of the quartz material of the crucible, wherein the two or more arc heaters are configured with a focus point below a surface of the melted material;
• guiding hot gas rising from the surface of the silicon melt through a guiding element configured to cause a portion of evaporated melted material to return to the melted material;
• and
• removing one or more impurities from the melted material to form a higher purity silicon material in the crucible.