| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent contamination to a semiconductor wafer by such impurities as heavy metal and so on generated from a reaction tube inwhich film formation is performed by CVD reaction. SOLUTION: In case film to be made is nitride (Si3 N4 ) film, inner pressure of reaction tube 3a is reduced to the degree as 20-30 pascal which is more than one during film making of a semiconductor wafer and reaction gas which has more than same flow volume during film making of the semiconductor wafer is provided from a gas supplying part to the reaction tube 3a. Regarding temperature distribution of heaters 3b1 -3b3 , the heater 3b1 located near an opening of the reaction tube 3a is heated about 830 deg.C, the heater 3b2 located at the central part of the reaction tube 3a and the heater 3b3 located near another opening of the reaction tube 3a are heated about 780 deg.C. After coating which forms thin film having about 1μm on all inner surface of the reaction tube 3a is performed under these conditions, film making on the semiconductor wafer starts.
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