Abstract: Method and system for purging a process line of a process gas used in a semiconductor wafer fabrication process. Inert gas (e.g., nitrogen gas) is repeatedly charged from an inert gas source into the process line and evacuated using a vacuum system. The vacuum system is preferably supplied with inert gas having a pressure in excess of 30 psig from the inert gas source. The inert gas is introduced into the process line from an inert gas conduit at a predetermined pressure to prevent process gas from liquefying in the process line. A set pressure regulator or an absolute pressure regulator may be used to reduce he pressure of the inert gas to below the vapor pressure of the process gas.

Abstract: A method, system, and storage medium for gas flow calibration of mass flow controllers (MFCs) is presented. A second mass flow controller that has a full scale range substantially less than that of a mass flow meter (MFM) may be calibrated by the MFM using a “gas biasing” technique. A first MFC is set such that a first flow of gas through the MFM at a first flow rate results. The first flow rate is preferably approximately 50% of the full scale range of the MFM. A first reading of the MFM is then recorded. The second MFC is then set such that a second gas flow of gas through the MFM at a second flow rate results. A second reading of the MFM is then recorded. The difference between the second and first readings is then compared to the set flow rate of the second MFC to determine the calibration of the second MFC. The full scale range of the second MFC may be less than 1% of the full scale range of the MFM.