| 摘要 |
PURPOSE:To suppress generation of air trap and form a silica film with very few defects by a method wherein a tube which feeds silica glass solution and through which the silica glass solution is made to flow is composed of an elastic tube and the tube is pinched by a pinching valve directly to control its opening and closing. CONSTITUTION:Silica solution 4 to which a pressure is applied by pressurized N2 through a pressurizing inlet 5 is made to flow through an elastic tube 8 such as a silicone tube and supplied to a coating cup 6. At that time, the tube 8 is pinched by a pinching valve 7 to control the opening and closing of the flow of the silica solution 4. With this constitution, an air-operated valve is not necessary and further, as a sucking valve mechanism which prevents dripping of solution is also provided by pinching the silicone tube 8 by the pinching valve 7, it is not necessary to attach an exclusive sucking valve. Therefore, air trap, caking of the silica glass, leakage and so forth in the tube system can be avoided. Thus, by opening and closing the elastic tube through which the silica glass solution flows with the pinching valve, a joint and a discontinued part such as an air-operated valve in the tube system can be eliminated and generation ofair trap and foreign substances in those parts can be suppressed.
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