| 摘要 |
PROBLEM TO BE SOLVED: To provide a thermal diffusion method and a vertical diffusion furnace for implementing the same method in which heating efficiency within a furnace core cylinder is improved, by preventing reduction in temperature near a furnace entrance to thereby reduce time for raising temperature, and stabilizing the raised temperature within the furnace core cylinder. SOLUTION: The vertical diffusion furnace 1 comprises a furnace core cylinder 2 and a main heater 3 for heating the inside of the cylinder 2 from the outer circumference of the cylinder 2. The furnace 1 also has a lower heater 7, which is provided at the lower end of a wafer transfer board 11, which vertically moves integrally with the board 11 so as to be in and out of the cylinder 2, and which heats an area near a furnace entrance 16 from a location inside the entrance 16 which is a lower region of the cylinder 2.
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