Apparatus for producing polycrystalline silicon
A polycrystalline silicon producing method with preventing meltdown and maintaining a high growing rate and a high yield by increasing temperature of raw material gas before supplying them to a reactor in a high pressure state so as to lower convection heat transfer from a silicon rod, including: supplying electric current to a silicon seed rod in a reactor to make the silicon seed rod to generate heat; and supplying a large amount of preheated raw material gas including chlorosilanes to the silicon seed rod in the reactor in the high pressure state.
1. A polycrystalline silicon producing apparatus which produces a silicon rod by supplying raw material gas including chlorosilanes to a silicon seed rod which is heated in a reactor so as to deposit polycrystalline silicon on the silicon seed rod, comprising: the reactor; the silicon seed rod which is disposed in the reactor; a power supply which supplies electric current to and heat the silicon seed rod; a pressure controller configured to control an inner pressure of the reactor in a range equal to or larger than 0.4 MPa and equal to or lower than 0.9 MPa; a thermometer which measures a surface temperature of the silicon rod; a current control device configured to control the surface temperature of the silicon rod measured by the thermometer in a range equal to or higher than 1000° C. and equal to or lower than 1100° C.; a raw material gas-supply source which supplies the raw material gas; a raw material gas-controller configured to control a supply amount of the raw material gas from the raw material gas-supply source; and a pre-heater configured to control the raw material gas in a range equal to or higher than 150° C. and equal to or lower than 600° C.; wherein the supply amount of the raw material gas is controlled by the raw material gas-controller configured to control a supply amount of chlorosilanes included in the raw material gas is in a range equal to or larger than 2.0×10 −7 mol/sec/mm 2 and equal to or smaller than 3.0×10 −2 mol/sec/mm 2 depending on a surface area of the growing silicon rod.
2. The polycrystalline silicon producing apparatus according to claim 1 , wherein the pre-heater is a heat exchanger which exchanges heats between a discharge gas from the reactor and the raw material gas before being supplied to the reactor.
3. The polycrystalline silicon producing apparatus according to claim 1 , wherein the reactor has a double-wall in which a coolant flows therein, and inner surface temperature of the double-wall is maintained in a range equal to or higher than 250° C. and equal to or lower than 400° C. by controlling temperature and a flow rate of the coolant.
4. The polycrystalline silicon producing apparatus according to claim 1 , wherein the reactor is provided with a raw material gas-supply nozzle which is connected to the raw material gas-supply source and is disposed further from an inner surface of the reactor than a silicon seed rod positioned at the outermost circumference.
5. The polycrystalline silicon producing apparatus according to claim 2 , wherein the reactor has a double-wall in which a coolant flows therein, and inner surface temperature of the double-wall is maintained in a range equal to or higher than 250° C. and equal to or lower than 400° C. by controlling temperature and a flow rate of the coolant.
6. The polycrystalline silicon producing apparatus according to claim 2 , wherein the reactor is provided with a raw material gas-supply nozzle which is connected to the raw material gas-supply source and is disposed further from an inner surface of the reactor than a silicon seed rod positioned at the outermost circumference.
7. The polycrystalline silicon producing apparatus according to claim 3 , wherein the reactor is provided with a raw material gas-supply nozzle which is connected to the raw material gas-supply source and is disposed further from an inner surface of the reactor than a silicon seed rod positioned at the outermost circumference.