Patent ID: 8747794

Claim:
A method for producing polycrystalline silicon comprising: fracturing into fragments polycrystalline silicon deposited on thin rods in a Siemens reactor; classifying the fragments into classified fragments having size classes of from about 0.5 mm to more than 45 mm; and treating the classified fragments with compressed air or dry ice to remove silicon dust from the classified fragments without wet chemical cleaning, wherein at least 90% of the classified fragments have a size from 10 to 40 mm, and the classified fragments contain: (a) less than 15 ppmw of silicon dust particles having particle sizes of less than 400 μm; (b) less than 14 ppmw of silicon dust particles having particle sizes of less than 50 μm; (c) less than 10 ppmw of silicon dust particles having particle sizes of less than 10 μm; (d) less than 3 ppmw of silicon dust particles having particle sizes of less than 1 μm; and (e) surface metal impurities in an amount greater than or equal to 0.1 ppbw and less than or equal to 100 ppbw.