System and method for forming a silicon wafer

A method of forming a crystalline ribbon from molten silicon comprising:

• melting solid silicon in a first chamber;
• floating a silicon crystal on a surface of a bed of molten silicon;
• heating the silicon crystal with a first heater comprising a plate defined along the silicon crystal in capacitive conductive relation to the silicon crystal;
• controlling a temperature of the molten silicon to a temperature at a melting point of molten silicon for initially heating the material and subsequently stabilizing the temperature surrounding the silicon crystal;
• maintaining the temperature of the molten silicon with a second heater for melting the molten silicon material;
• capacitively coupling radio frequency electrical currents into the molten silicon causing a portion of the silicon crystal to melt along a zone;
• and
• removing heat from the silicon crystal in a direction substantially perpendicular to the surface of the liquid silicon to effect silicon crystal growth of the silicon crystal;
• causing relative motion parallel to the surface of the molten silicon between the ribbon and the heater;
• and
• feeding molten silicon into the crucible from the first chamber at a defined rate.

An apparatus for forming a crystalline ribbon from molten silicon

• comprising:
• a crucible configured to hold molten silicon, the crucible having a formation portion, and a feed mechanism configured to feed molten silicon into the crucible at a predetermined rate;
• a first heater electrode positioned a distance from moving molten silicon in capacitive conductive relation to the moving molten silicon and having a controller for controlling a temperature just above a melting point of the moving molten silicon for initially heating moving molten silicon and subsequently stabilizing the temperature surrounding a wedge portion of the crystalline ribbon;
• a second heater electrode displaced from and non-parallel to the first heater electrode, positioned a distance from the moving molten silicon in capacitive conductive relation to the moving molten silicon and the first heater electrode, the second heater electrode configured to impart a heat of fusion to the moving molten silicon along and at a ribbon tip causing a ribbon of material to melt along a zone;
• the controller configured to control application of RF energy to the moving molten silicon by the first and second electrodes and control the level of the molten silicon in the crucible;
• and
• a mechanism for causing relative motion parallel to the surface of the molten silicon between the ribbon and the heater.

An apparatus for forming a crystalline ribbon from a source of molten silicon comprising:

• first and second heating electrodes;
• a crucible configured to hold molten silicon, the crucible having a formation portion, said formation portion having a flange member that supports and holds the molten silicon between the flange and the crystalline ribbon, the level of the molten silicon being controlled by a movable piston;
• the first heating electrode comprising a temperature regulator in thermally conductive relation to the ribbon for heating a wedge portion of the ribbon and subsequently stabilizing the temperature surrounding the wedge portion of the ribbon;
• the second heating electrode for maintaining the temperature of the molten silicon, wherein second heater electrode is in capacitively conductive relation with both the first heating electrode and the molten silicon to provide a capacitive path from the first heating electrode past the crystalline ribbon;
• a controller coupled to a cooler for removing heat from the crystalline ribbon in a direction substantially perpendicular to a surface of the molten silicon to effect ribbon growth and to the piston;
• and
• a mechanism for causing relative motion parallel to the plane between the ribbon and the first heating electrode;
• the mechanism being controlled by the controller.