Method for producing silicon ingot having directional solidification structure and apparatus for producing the same

A method for producing a silicon ingot having a directional solidification structure, the method comprising:

• placing a silicon raw material into a crucible of a melting device constructed by mounting a chill plate on an underfloor heater, mounting the crucible on the chill-plate, providing an overhead heater over the crucible, and surrounding a circumference of the crucible with a heat insulator;
• heat-melting the silicon raw material in the crucible maintained under an inert gas atmosphere by flowing electric current through the underfloor heater and the overhead heater without feeding a refrigerant to the chill plate, followed by halting or decreasing the electric current through the underfloor heater after the silicon raw material has been completely melted, the molten silicon being chilled from a bottom of the crucible by chilling the chill plate by feeding the refrigerant;
• and
• intermittently or continuously lowering a temperature of the overhead heater by intermittently or continuously decreasing the electric current through the overhead heater along with halting the electric current or decreasing the electric power through the underfloor heater.

A method for producing a silicon ingot having a directional solidification structure, the method comprising:

• placing a silicon raw material into a crucible of a melting device constructed by mounting a chill plate on an underfloor heater, mounting the crucible on the chill plate, providing an overhead heater over the crucible, and surrounding a circumference of the crucible with a heat insulator;
• heat-melting the silicon raw material in the crucible by flowing electric current through the underfloor heater and the overhead heater while maintaining an inert gas atmosphere in the crucible by feeding a small amount of the inert gas, insufficient to chill the chill plate, into the crucible through a gas passage, followed by halting or decreasing the electric current through the underfloor heater after the silicon raw material has been completely melted along with chilling the molten silicon from a bottom of the crucible by feeding an amount of the inert gas to the chill plate, maintaining the inert gas atmosphere in the crucible by feeding a part of the inert gas used for chilling the chilling plate into the crucible;
• and
• intermittently or continuously lowering a temperature of the overhead heater by intermittently or continuously decreasing the electric current through the overhead heater along with halting the electric current or decreasing the electric power through the underfloor heater.