| 摘要 |
A gas flow monitoring system is provided in process gas lines each arranged to supply gas to a predetermined process chamber via a flow control device, the system being configured to measure lowering or rising of gas pressure before and after the flow control device to monitor a flow rate of the flow control device. The system includes a first flow monitoring unit placed upstream of the flow control device in a selected one of the process gas lines, a second flow monitoring unit placed in a discharge passage upstream of the process chamber, and a controller that constantly monitors the flow rate of the flow control device with the first flow monitoring unit and, when the first flow monitoring unit detects the flow-rate abnormality two or more times, commands the second flow monitoring unit to re-verify whether flow-rate abnormality is present or not in the flow control device.
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