Patent ID: 8262797

Claim:
An apparatus for growing ingots by the Czochralski method, the ingots being drawn from a melt/crystal interface in a quantity of molten silicon replenished by crystalline feedstock, the apparatus comprising: a growth chamber defining an enclosure configured to circulate a purge gas about the growing ingot; a crucible provided in the growth chamber configured to hold the molten silicon, a heat shield comprising a conical body having a base and downwardly depending sidewalls extending into the growth chamber and tapering conically to define an annular opening configured to receive the ingot drawn from the melt/crystal interface; a weir supported in the crucible, and configured to separate the molten silicon into an inner growth region surrounding the crystal/melt interface from an outer region configured to receive the crystalline feedstock, the weir comprising sidewalls extending vertically and terminating in a peripheral edge adjacent to the sidewalls of the heat shield to define an annular space with respect to the sidewalls of the heat shield, wherein the annular space is sized to restrict entry of dust into the growth region; and an inner weir disposed within the weir, the inner weir defining a middle interconnecting region between the inner growth region and the outer region.