| 摘要 |
Silicon single crystals are pulled from a melt in a crucible, the single crystal surrounded by a heat shield, the lower end of which is a distance h from the melt surface, wherein gas flows downward between the single crystal and the heat shield, outward between the lower end of the heat shield and the melt, and then upward in the region outside the heat shield. The internal diameter of the heat shield at its lower end is 55 mm or more than the diameter of the single crystal, and the radial width of the heat shield at its lower end is not more than 20% of the diameter of the single crystal. Highly doped single crystals pulled accordingly have a void concentration ≦̸50 m−3.
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