| 摘要 |
PURPOSE:To introduce uniformly an oxidizing gas in the widthwise direction of a substrate, to dispense with a large amt. of oxidizing gas and to make the coercive force of the obtained substrate uniform in the widthwise direction by preventing the diffusion of the oxidizing gas, which is directed to the vapor injection part of the substrate from a gas introducing pipe, from both end edge sides of a cylindrical can. CONSTITUTION:A gas diffusion-preventive plate 11 has a height of (h) which is >=1/2 of the shortest distance H between a substrate 4 moving along the peripheral side surface of a cylindrical can 3 and the lower gas introducing pipe 10 and the length (l) of the plate is regulated to >=1/3 of the radius (r) of the cylindrical can 3. When the oxidizing gas is blown from the gas introducing pipe 10 on the vapor injection part of the substrate 4 moving along the peripheral side surface of the cylindrical can 3, the diffusion of the oxidizing gas from both end edge sides of the cylindrical can 3 is prevented by the gas diffusion-preventive plate 11 and the gas is uniformly blown on the whole width of the substrate 4.
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