METHOD FOR PRODUCING SILICON USING MICROWAVE, AND MICROWAVE REDUCTION FURNACE

Abstract

A microwave reduction furnace including a reaction furnace provided with a refractory chamber of silica or silicon carbide for storing a material therein, a supply section for supplying the material into the refractory chamber, the material being a mixture of a silica powder and a graphite powder or a mixture of a silica powder, a silicon carbide powder and a graphite powder, a discharge section for discharging molten silicon, obtained through reduction, out of the chamber, and a microwave oscillator for outputting microwave toward the refractory chamber in the reaction furnace with a degree of directionality by virtue of a helical antenna or a waveguide.

Claims

1. A microwave reduction furnace comprising: a reaction furnace provided with a refractory chamber of silica or silicon carbide for storing a material therein; a supply section for supplying the material into the refractory chamber, the material being a mixture of a silica powder and a graphite powder or a mixture of a silica powder, a silicon carbide powder and a graphite powder; a discharge section for discharging molten silicon, obtained through reduction, out of the chamber; and a microwave oscillator for outputting microwave toward the refractory chamber in the reaction furnace with a degree of directionality by virtue of a helical antenna or a waveguide.

2. A microwave reduction furnace comprising: a reaction furnace provided with a refractory chamber of silica or silicon carbide, the reaction furnace being capable of storing a material therein and preventing a generated gas from escaping; a supply section for supplying the material into the refractory chamber, the material being a mixture of a silica powder and a graphite powder or a mixture of a silica powder, a silicon carbide powder and a graphite powder; a discharge section for discharging molten silicon, obtained through reduction, out of the chamber; and a microwave oscillator for outputting microwave toward the refractory chamber in the reaction furnace with a degree of directionality by virtue of a helical antenna or a waveguide, wherein an SiO gas is produced as an intermediate product through a reduction reaction between the silica and the silicon carbide and/or the graphite, and the SiO gas is allowed to be in contact with silica, graphite and/or silicon carbide while preventing the SiO gas from escaping out of the refractory chamber, thus reducing silica through a gas-solid reduction reaction, thereby allowing for continuous production of the molten silicon.

3. A microwave reduction furnace comprising: a reaction furnace provided with a refractory chamber of silica or silicon carbide for storing a material therein; a supply section for supplying the material into the chamber, the material being a mixture of a silica powder and a graphite powder or a mixture of a silica powder, a silicon carbide powder and a graphite powder; a discharge section for discharging molten silicon, obtained through reduction, out of the chamber; a microwave unit arranged on an inner surface of a circumferential surface surrounding the refractory chamber for radiating a microwave beam toward a particular point in the refractory chamber; and a main reflection mirror arranged above the refractory chamber, the main reflection mirror having a paraboloid whose focal point coincides with the particular point and which paraboloid serves as a reflection surface for microwave.

4. A microwave reduction furnace comprising: a reaction furnace provided with a refractory chamber of silica or silicon carbide for storing a material therein; a microwave window surrounding the reaction furnace; a melting furnace top plate supported by the microwave window for covering the refractory chamber so as to prevent a generated gas from escaping; a supply section for supplying the material into the refractory chamber through the melting furnace top plate, the material being a mixture of a silica powder and a graphite powder or a mixture of a silica powder, a silicon carbide powder and a graphite powder; a discharge section for discharging molten silicon, obtained through reduction, out of the chamber; a microwave unit arranged on an inner surface of a circumferential surface surrounding the refractory chamber for radiating a microwave beam toward a particular point in the refractory chamber; and a main reflection mirror arranged above the refractory chamber, the main reflection mirror having a paraboloid whose focal point coincides with the particular point and which paraboloid serves as a reflection surface for microwave, wherein an SiO gas is produced as an intermediate product through a reduction reaction between the silica and the silicon carbide and/or the graphite, and the SiO gas is allowed to be in contact with silica, graphite and/or silicon carbide while preventing the SiO gas from escaping out of a housing constructed by the refractory chamber and the melting furnace top plate, thus reducing silica through a gas-solid reduction reaction, thereby allowing for continuous production of the molten silicon.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0087] FIG. 1 A vertical-sectional view showing a microwave reduction furnace for use with a method for producing silicon using microwave according to an embodiment of the present invention.

[0088] FIG. 2 A partial plan view showing a weir portion thereof.

[0089] FIG. 3 A vertical-sectional view showing a melting furnace of a microwave reduction furnace according to another embodiment of the present invention.

[0090] FIG. 4 A diagram showing a stepped reflection mirror thereof.

[0091] FIG. 5 A perspective view showing the entire microwave reduction furnace.

REFERENCE SIGNS LIST

[0092] 2: Material mixture powder (SiO.sub.2+SiC+C or SiO.sub.2+C) [0093] 3: Molten silicon [0094] 12, 51a: Silica reaction chamber [0095] 13, 62: Tapping hole [0096] 16, 63: Tapping pipe [0097] 17, 18, 64: Heater [0098] 31: Reaction furnace [0099] 32: Furnace body [0100] 33: Microwave oscillator [0101] 34: Microwave transmitting antenna [0102] 41: Support plate [0103] 42: Semiconductor 500 W module [0104] 43: Microwave unit [0105] 50: Melting furnace [0106] 51: Reaction furnace [0107] 51b, 52: Heat-insulating material [0108] 53: Main reflection mirror [0109] 53a: Microwave mirror surface [0110] 54: Microwave window [0111] 55: Stepped reflection surface [0112] 56: Sub-reflection mirror [0113] 57: Auxiliary reflection mirror