| 摘要 |
The temperature of the front heater is set to a higher value than the set temperature of the center heater and the temperature of the rear heater is set to a lower value than the set temperature of the center heater to thereby provide such a temperature gradient that the temperature of a center heater region gradually rises from the rear side toward the front side and the impurity diffusion is accelerated under the temperature gradient, whereby it is possible to compensate for the decrease in the quantity of the diffused impurity caused by the lowering of the impurity concentration of the impurity gas gradually from the rear side toward the front side, so that the impurity is uniformly diffused into the wafers located in the core pipe.
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