CRYSTAL PULLING SYSTEMS AND METHODS FOR PRODUCING MONOCRYSTALLINE INGOTS WITH REDUCED EDGE BAND DEFECTS

摘要

A crystal pulling system for growing a monocrystalline ingot from a melt of semiconductor or solar-grade material includes a crucible for containing the melt of material, a pulling mechanism configured to pull the ingot from the melt along a pull axis, and a multi-stage heat exchanger defining a central passage for receiving the ingot as the ingot is pulled by the pulling mechanism. The heat exchanger defines a plurality of cooling zones arranged vertically along the pull axis of the crystal pulling system. The plurality of cooling zones includes two enhanced-rate cooling zones and a reduced-rate cooling zone disposed vertically between the two enhanced-rate cooling zones.

主权项

1. A crystal pulling system for growing a monocrystalline ingot from a melt of semiconductor or solar-grade material, the system comprising:
a crucible for containing the melt of semiconductor or solar-grade material; a pulling mechanism configured to pull the ingot from the melt along a pull axis; and a multi-stage cooling system configured to cool the ingot at different cooling rates as the ingot is pulled from the melt by the pulling mechanism, the cooling system including:
an annular heat shield positioned concentric with the crucible and defining an elongate passage for receiving the ingot; anda multi-stage heat exchanger positioned within the passage defined by the heat shield, the heat exchanger including a fluid-cooled housing defining a central passage for receiving the ingot, the housing having an upper portion and a lower portion spaced vertically from the upper portion by an annular gap.