| 摘要 |
PURPOSE:To obtain an excellent internal pressure for a reaction chamber in the CVD method by connecting lots of digital valves suitable for fine quantity adjustment in a gas line in parallel, dividing the line into minute divisions so as to obtain a desired flow timewise through the sequential valve opening operation. CONSTITUTION:A gas in a reaction chamber 4 is sucked by a suction pump P via digital valves V1-V4, a change of a pressure by the measurement of a pressure guage 6 is sensed by a controller to keep the pressure in the chamber 4 always constant and the digital valves V1-V4 are operated. When a gas flow of 1l/min flows always in the reaction chamber 4 and a pressure of 100 Torr is kept, the release time of one digital valve is selected to 1/4min and each digital valve is operated in a cycle of 1min continuously. In case of a gas line with a flow of 2l/min, the release time of seven digital valves is selected as 2/4min and each digital valve is operated at an interval of 1/4min in a cycle of 1min. |
