Patent ID: 7060133
Filing Date: 2006-06-13
Classification: C30B,Y10T

Abstract:
1. A single crystal pulling apparatus for a metal fluoride, comprising: a chamber constituting a crystal growth furnace; a crucible provided in the chamber for filling with a molten solution of a single crystal material; a melting heater provided to surround the crucible; a vertically movable single crystal pulling bar for attaching a seed crystal on a tip and adapted to come in contact with the molten solution of the single crystal material in the crucible; a heat insulating wall provided in the chamber to surround at least a peripheral side portion of a single crystal pulling region in an upper part of the crucible; a ceiling board for closing an opening portion of an upper end in an upper part of the heat insulating wall; and a single crystal pulling chamber surrounded by the heat insulating wall and the ceiling board, wherein the single crystal pulling chamber is defined by a single crystal pulling region which vertically extends from an upper end of the crucible to a height that an upper end of the single crystal of a metal fluoride to be grown reaches at the end of pulling, terminating at a location below said ceiling board; and wherein the ceiling board is provided with at least an inserting hole for inserting the single crystal pulling bar, and the ceiling board has a coefficient of thermal conductivity in a direction of a thickness of the ceiling board of 1000 to 50000 W/m