Patent ID: 8551580

Claim:
A polycrystalline silicon producing method comprising: supplying electric current to at least one silicon seed rod in a reactor to make the silicon seed rod to generate heat; supplying raw material gas including chlorosilanes in the reactor in which the silicon seed rod is provided; and depositing polycrystalline silicon on a surface of the silicon seed rod to be grown as a silicon rod, wherein a pressure in the reactor is maintained in a range equal to or greater than 0.4 MPa and equal to or less than 0.9 MPa, a surface temperature of the silicon rod is maintained in a range equal to or higher than 1000° C. and equal to or lower than 1100° C., the raw material gas is preheated to a range equal to or higher than 150° C. and equal to or lower than 600° C. and then supplied to the reactor so as to maintain a chlorosilanes supply amount per unit time and per unit surface area in a range equal to or greater than 2.0×10 −7 mol/sec/mm 2 and equal to or less than 3.0×10 −7 mol/sec/mm 2 with growth of the diameter of the silicon rod.