| 摘要 |
PURPOSE:To form a deposited film of high quality on a substrate at a high speed in a good efficiency by suppressing the formation of the film in an exciting energy transmitting window, and preferably maintaining the energy transmittivity of the window even after the use for a long period. CONSTITUTION:The part of a material gas introduction tube 6 passes a cooler 18, for example, in a spiral state to increase the length of the tube in the cooler, thereby enhancing the cooling effect. The end hole of the tube 6 is disposed in the upper portion in a reaction vessel 2, i.e., near a light transmitting window 4, and directed downward of the window 4 substantially horizontally. Since the vicinity of the window 4 in the vessel 2 and the inner surface of the window 4 are cooled in this manner, a photochemical reaction here is suppressed to remarkably reduce the formation of the film on the inner surface of the window 4.
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