Abstract: Switches (S1-S3) allow switching between parallel/series configuration in a circuit (16) provided between two pairs of U-shaped silicon cores (12) arranged in a bell jar (1). In the circuit (16), current is supplied from one low-frequency power source (15L) supplying a low-frequency current, or from one high-frequency power source (15H) supplying a high-frequency current having a frequency of not less than 2 kHz. The two pairs of U-shaped silicon cores (12) (or polycrystalline silicon rods (11)) are connected to each other in series by closing the switch (S1) and opening the switches (S2 and S3), and when the switch (S4) is switched to the side of the high-frequency power source (15H), and electric heating of the silicon cores (12) can be performed by supplying a high-frequency current having a frequency of less than 2 kHz to the series-connected U-shaped silicon cores (12) (or polycrystalline silicon rods (11)).

Abstract: 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.

Abstract: In order to obtain a polycrystalline silicon rod having an excellent shape, the placement relation between a source gas supplying nozzle 9 and metal electrodes 10 that are provided in a reactor is appropriately designed. The area of a disc-like base plate 5 is S0. An imaginary concentric circle C (radius c) centered at the center of the disc-like base plate 5 has an area S=S0/2. Further, a concentric circle A and a concentric circle B are imaginary concentric circles having the same center as that of the concentric circle C and having a radius a and a radius b, respectively (a<b<c). In the present invention, the electrode pairs 10 are placed inside of the imaginary concentric circle C and outside of the imaginary concentric circle B, and the gas supplying nozzle 9 is placed inside of the imaginary concentric circle A.