A method for processing polycrystalline silicon workpieces to form size
distributions of polycrystalline silicon pieces suitable for use in a
Czochralski-type process includes: (1) preparing a polycrystalline silicon
workpiece by a chemical vapor deposition process; (2) fracturing the
polycrystalline silicon workpiece into a mixture of polycrystalline
silicon pieces, where the polycrystalline silicon pieces have varying
sizes; and (3) sorting the mixture of polycrystalline silicon pieces into
at least two size distributions. Step (2) may be carried out by a thermal
shock process. Step (3) may be carried out using a rotary indent
classifier. A rotary indent classifier for performing the method includes:
(i) a rotating cylinder having a circumferential edge with indents arrayed
in increasing size from a first end of the cylinder to a second end of the
cylinder, and (ii) a conveyor running longitudinally adjacent the
cylinder, for conveying silicon pieces from the first end of the cylinder
to the second end of the cylinder.
