| 摘要 |
PURPOSE:To prevent the dispersion of characteristics due to thermal hysteresis difference given to materials to be treated and the generation of the defects of crystals due to thermal distortion by a method wherein a cover is opened interlocking with a drawing bar when drawing a boat. CONSTITUTION:The cover 14 has a hole, and can be moved apart from the drawing bar 13. The cover 14 rests at a pipe port at the same time as the whole range of the boat 11 is completely inserted into a furnace center pipe 15. When the drawing bar 13 is drawn after heat treatment, the cover 14 is removed by means of a pawl 16 mounted to the bar 13. According to this constitution, the substantial speed of heating can be delayed when wafers 12 are inserted into the furnace center pipe, and the speed of cooling is also delayed extremely when the wafers are drawn, and the generation of the defects of crystals due to thermal distortion can be prevented. |
