Process for preparing highly pure silicon granules

A process for preparing silicon granules with a chlorine contamination below 50 ppm by weight by deposition of elemental silicon on silicon particles in a fluidized bed reactor comprising:

• establishing in a fluidized bed reactor having a heating zone below a reaction zone, a fluidized bed of silicon particles;
• and fluidizing said silicon particles, in the heating zone, by means of an inert silicon-free carrier gas passing upwardly, first through the heating zone and then through the reaction zone, to produce said fluidized bed of silicon particles in the reactor;
• introducing a reaction gas, comprising a silicon source gas and a carrier gas through at least one tubular nozzle, directly into the reaction zone of the fluidized bed reactor;
• heating said silicon particles in the heating zone by means of microwave energy;
• reacting the silicon particles in the reaction zone with said reaction gas and said reaction gas passing upwardly through said fluidized silicon particles, and maintaining an average temperature of the reaction gas in the reaction zone at from 491.degree. C. to 894.degree. C..