| 摘要 |
PURPOSE:To uniformly diffuse impurity to a semiconductor wafer and make small dispersion of characteristic by comprising a cylindrical furnace core tube having the exhaust tubes at both ends, a plurality of gas injection exhaust ports sorted to the upper and lower sections of furnace core tube and an internal tube from which both ends the gas is supplied. CONSTITUTION:The gas supplied from the gas sending tubes 13, 14 is injected from many gas injection port provided at the upper part of internal tube 12 and is exhausted to the outside of furnace core tube 11 through the exhaust tube 15 from many gas exhaust ports provided to the lower part of internal tube 12. Therefore, the semiconductor wafer 5 is uniformly in the contact with the gas, impurity diffusion to the wafer 5 becomes uniform and dispersion becomes small. Since the wafer 5 is in contact with fresh gas, concentration of impurity in the gas is not different. Moreover, since gas is supplied from both ends, gas injection amount is more equalized. In addition, since the gas is exhausted from many exhaustion ports provided to the lower part of internal tube 12, flow of gas in the internal tube is also more equalized.
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