PRODUCTION METHOD FOR POLYCRYSTALLINE SILICON, AND REACTOR FOR POLYCRYSTALLINE SILICON PRODUCTION

摘要

The present invention provides a method of producing polycrystalline silicon in which silicon is precipitated on a silicon core wire to obtain a polycrystalline silicon rod. In an initial stage (former step) of a precipitation reaction, a reaction rate is not increased by supplying a large amount of source gas to a reactor but the reaction rate is increased by increasing a concentration of the source gas to be supplied, and in a latter step after the former step, the probability of occurrence of popcorn is reduced using an effect of high-speed forced convection caused by blowing the source gas into the reactor at high speed. Thus, a high-purity polycrystalline silicon rod with little popcorn can be produced without reducing production efficiency even in a reaction system with high pressure, high load, and high speed.

主权项

1. A method of producing polycrystalline silicon by a Siemens method, comprising:
supplying a source gas comprising a chlorosilane gas and a hydrogen gas from a nozzle port into a reactor, and reacting the source gas to precipitate polycrystalline silicon on a silicon core wire, wherein: the source gas is initially supplied at a first gas supply amount, then supplied at a second gas supply amount, then supplied at a third gas supply amount greater than the first gas supply amount, wherein the second gas supply amount increases from a value of the first gas supply amount to a value of the third gas supply amount; the reacting is performed at a reaction temperature of 900° C. to 1250° C. and under a reaction pressure of 0.3 to 0.9 MPa; a flow rate at the nozzle port is 150 m/sec or more when the source gas is supplied at the third gas supply amount, and the supplying of the source gas and a silicon rod temperature are controlled under the following conditions A to C depending on a diameter D of a polycrystalline silicon rod that changes with progression of a precipitation reaction after a reaction start: condition A: the chlorosilane gas is supplied in an amount one third or less of a maximum chlorosilane gas supply amount until a predetermined value D1 of 15 mm to 40 mm is reached, the supply amount is increased continuously or stepwise until the maximum chlorosilane gas supply amount is reached between when the D1 is reached and when a predetermined value D2 of 15 mm to 40 mm and larger than the D1 is reached, and the maximum chlorosilane gas supply amount is maintained after the D2 is exceeded; condition B: the hydrogen gas is supplied so that a chlorosilane gas concentration in the source gas is 30 mol % to less than 40 mol % until the D1 is reached, a ratio of the supply amount of the hydrogen gas to the chlorosilane gas is increased continuously or stepwise after the D1 is reached, and the hydrogen gas is supplied so that the chlorosilane gas concentration in the source gas is 15 mol % to less than 30 mol % after the D2 is reached; and condition C: the temperature of the silicon rod is reduced with increasing diameter of the silicon rod after the D2 is reached.