A Study on the Real-Time Flow Rate Change Monitoring Methods of Mass Flow Controller in In-Situ Semiconductor Processing

The actual flow change monitoring method proposes a method to detect Mass Flow Controller (MFC) defects in real-time. MFC is based on a feedback system. When MFC system receives the goal point (Setpoint) from the equipment, the sensor indicates current flow (Flow) while the valve controls the flow rate (Valve Open amount). These sensors and valve data are controlled by the microprocessor in MFC. The engineering system only monitors the Setpoint and the Flow. However, this data cannot represent the value of real flow since the thermal sensor type MFC measures only 5% sampling data of the total gas flow. For the system to manage the changes in the real flow, it should monitor sensor data and Valve Open amount data. Moreover, there is a need to consider inlet pressure and MFC's temperature, which affect the flow rate and valve position. When the system monitors the Valve Open amount, the flow experiences problems such as flow contamination and thermal sensor drift. As a result, the system can detect the problem of Mass Flow Controller.