Flowable Chips and Methods for the Preparation and Use of Same, and Apparatus for Use in the Methods

A process for casting silicon on a substrate comprising:

• 1) melting silicon comprising flowable chips to form molten silicon,
• where said flowable chips comprising polycrystalline silicon pieces are prepared by a chemical vapor deposition process and have a controlled particle size distribution, where at least 75% of the particles have a particle size of 0.2 to 45 mm, generally nonspherical morphology, a level of bulk impurities not exceeding 0.03 ppma, and a level of surface impurities not exceeding 15 ppba,
• 2) pouring the molten silicon into a heated mold, and
• 3) allowing the molten silicon to slowly cool and solidify.

A method comprising:

• a) pulling a silicon ingot from a crucible in a Czochralski-type process;
• b) adding flowable chips to molten silicon in the crucible, where flowable chips comprise polycrystalline silicon pieces prepared by a chemical vapor deposition process and have a controlled particle size distribution, generally nonspherical morphology, low levels of bulk impurities, and low levels of surface impurities;
• and
• c) optionally adding a dopant to the crucible.

A method comprising:

• 1) introducing a semiconductive material comprising flowable chips into a casting mold comprising walls defining a desired cross sectional-shape,
• said flowable chips comprising polycrystalline silicon pieces prepared by a chemical vapor deposition process and having a controlled particle size distribution, where at least 75% of the particles have a particle size of 0.2 to 45 mm, generally nonspherical morphology, a level of bulk impurities not exceeding 0.03 ppma, and a level of surface impurities not exceeding 15 ppba,
• 2) melting the semiconductive material, and
• 3) solidifying the semiconductive material after step 2) to produce a cast ingot having the desired cross sectional-shape.