System for continuous growing of monocrystalline silicon

Abstract

An improved system based on the Czochralski process for continuous growth of a single crystal ingot comprises a low aspect ratio, large diameter, and substantially flat crucible, including an optional weir surrounding the crystal. The low aspect ratio crucible substantially eliminates convection currents and reduces oxygen content in a finished single crystal silicon ingot. A separate level controlled silicon pre-melting chamber provides a continuous source of molten silicon to the growth crucible advantageously eliminating the need for vertical travel and a crucible raising system during the crystal pulling process. A plurality of heaters beneath the crucible establish corresponding thermal zones across the melt. Thermal output of the heaters is individually controlled for providing an optimal thermal distribution across the melt and at the crystal/melt interface for improved crystal growth. Multiple crystal pulling chambers are provided for continuous processing and high throughput.

1 . An apparatus for effecting substantially uniform melting of a charge of silicon or polysilicon crystalline material including solid chunks, rods, or granules characterized by a major dimension on the order of limn or less comprising:
 a low aspect ratio, wide diameter crucible having shallow sidewalls for holding the charge of silicon or polysilicon material;   a plurality of independently controlled heaters disposed beneath the crucible for establishing corresponding thermal zones through the melt, such that heat is driven uniformly by higher surface area of contact and shorter thermal path into the charge in the crucible, including solid chunks, rods or granules;   means for thermally activating each heater to achieve an optimal thermal distribution across the melt such that granules are melted uniformly at a desired rate; and   control means for selectively controlling thermal output of each heater by monitoring power consumed by each heater to maintain the optimal thermal distribution across the melt.   
     
     
         2 . An apparatus according to  claim 1  further comprising a weir disposed centrally in the crucible for defining a first melting region outboard of the weir with respect to the sidewalls of the crucible and defining a second crystal growing region inboard of the weir for pulling a crystal from the molten silicon or polysilicon crystalline material.