| 摘要 |
Polycrystalline silicon rod comprises a core (A) with a porosity of 0-0.01 around a thin rod, and at least two consecutive layers, which differ in their porosities by a factor of 1.7-23, where the outer layer (C) is less porous than the layer (B), and the polycrystalline silicon rod has an overall diameter of at least 150 mm. Independent claims are also included for: (1) manufacturing polysilicon fragments comprising crushing the above mentioned polycrystalline silicon rod; (2) the polycrystalline silicon fragments comprising fragments having different porosities and the fragments having a curved surface with a curvature radius of at least 75 mm, which are produced by the above mentioned method; and (3) producing the polycrystalline silicon rods, comprising introducing a reaction gas containing a silicon-containing component and depositing polycrystalline silicon on thin rods until a target rod diameter is achieved, which includes (a) depositing the core on thin rods in each case until a rod diameter of 15-60 mm is achieved, where the rod temperature is 1000-1150[deg] C, the concentration of the silicon-containing component in the reaction gas is 20-60 mole% and the supply of the silicon-containing component is 100-550 kg/hour per 1 m 2> of rod surface, (b) depositing a layer (B) with a porosity of 0.06-0.23 on the core starting with a rod diameter of at least 10% to a rod diameter of not > 90% of the target rod diameter, where the rod temperature is 1030-1130[deg] C, the concentration of the silicon-containing component in the reaction gas is 20-40 mole%, and the supply of the silicon-containing component is 80-200 kg/hour per 1 m 2> of the rod surface, and (c) depositing a layer (C) having a porosity of 0.01-0.1 on the layer (B), starting with a rod diameter of at least 50% up to a rod diameter of not > 100% of the target rod diameter, where the rod temperature is 960-1030[deg] C and is at least 20[deg] C lower than the rod temperature maintained during the step (b), the concentration of the silicon-containing component in the reaction gas is 15-35 mole% and the supply of the silicon-containing component is 10-130 kg/hour per 1 m 2> of the rod surface. |
