| 摘要 |
<p>Granular polycrystalline silicon with a convexity of 0.850-1.000, a chlorine content of 10-40 ppmw and a nitrogen content of 10-100 ppba is disclosed. Also disclosed is a process for producing granular polycrystalline silicon in a fluidized bed reactor, which includes: (a) fluidization of silicon seed particles by gas flow in a fluidized bed heated by a heating apparatus, (b) addition of trichlorosilane resulting in pyrolytic deposition of elemental silicon on heated seed particle surfaces, (c) forming the granular polycrystalline silicon, (d) removing from the reactor particles and offgas containing HCl, and (e) metered addition of fresh seed particles. The HCl concentration in the offgas is determined as the controlled variable. The rate of metered addition of fresh seed particles and heating output of the heating apparatus are controlled as manipulated variables to keep the HCl concentration in the offgas within 1.8-2.5% by volume during operation.</p> |
