ADDRESSING FIRST WAFER EFFECT
In idle mode the volume between the mass flow controller (MFC) control valve and downstream pneumatic isolation valve can become pressurized with process gas due to normal small leakage past the MFC’s control valve when in the closed position.
During the first process setpoint, this volume of unmetered gas can impact the first wafer.
Controlling internal MFC dead-volume after the valve and improving the valve shut-off by >100X virtually eliminates any potential process impact.