초록 ▼

The present invention is directed to an improved process for producing ultra high purity polycrystalline silicon which process provides for increased production capacity and electrical power efficiency. The process comprises recycling the exhaust gases of the silane pyrolysis reactor after the gases

The present invention is directed to an improved process for producing ultra high purity polycrystalline silicon which process provides for increased production capacity and electrical power efficiency. The process comprises recycling the exhaust gases of the silane pyrolysis reactor after the gases have been preferably first cooled and filtered utilizing a pocket-type reaction zone enclosure having a particular effective radius thereby effectively decreasing the amount of silicon powder formation. Preferably, the rate of recycle flow is sufficient to entrain silicon powder in the reactor and remove the powder from the reactor with the exiting exhaust gases.

대표청구항 ▼

A process for the formation of polysilicon crystal rods in which the formation of silicon powder is reduced comprising: (a) providing an elongated starter rod substantially in the center of a cooled enclosure which enclosure has a wall at an effective radius of from about 6 cm. to 23 cm. and an uppe

A process for the formation of polysilicon crystal rods in which the formation of silicon powder is reduced comprising: (a) providing an elongated starter rod substantially in the center of a cooled enclosure which enclosure has a wall at an effective radius of from about 6 cm. to 23 cm. and an upper outlet and a lower inlet; (b) energizing the starter rod while introducing silane into the cooled enclosure, said starter rod being maintained at a temperature sufficient to effect silicon decomposition and deposition thereon and forming a thermal boundary layer around the periphery of said rod and produce by homogeneous decomposition silicon powder, said silane being provided at a rate sufficient to maintain the silane concentration in the cooled enclosure in an amount of at least about 0.5 mole percent; and (c) continuing step (b) for a time sufficient to grow a silicon rod having a diameter no greater than about 80 to 90% of the diameter of the enclosure, and while growing said rod: (i) maintaining the wall of the enclosure at a temperature below about 100°C.; (ii) removing at least a portion of an effluent comprised of unreacted silane, silicon powder and by-product hydrogen from the upper outlet of the enclosure; and (iii) recycling the effluent at a rate of at least about 50,000 cubic cm./min. to the lower inlet of the enclosure.