HEAT TREATMENT FURNACE FOR SEMICONDUCTOR SUBSTRATE

PURPOSE:To provide a heat treatment furnace for semiconductor substrate which is capable of significantly reducing the metal contamination level of a heat-treated semiconductor substrate. CONSTITUTION:A heat treatment furnace has a furnace tube 4 located on a base plate 1 and housing a boat 5 therein, an external tube 3 located outside the furnace tube 4, a heater 2 located outside the external tube 3, and a sealing chamber 8 for sealing the external tube 3 and the heater 2. A plurality of semiconductor substrates 7 are housed in the boat 5. A purge gas introduction tube 9 for introducing a purge gas between the furnace tube 4 and the external tube 3 is provided through the base plate 1. Also, a cooling gas introduction tube 11 for introducing a cooling gas between the external tube 3 and the sealing chamber 8 is provided through the base plate 1. The purge gas supplied from the purge gas introduction tube 9 is a nitrogen gas containing 0.01-0.1% of oxygen.