Flow metrology calibration for improved processing chamber matching in substrate processing systems

A calibration system for an orifice-based flow metrology system, comprising:

• a gas box including valves and mass flow controllers to selectively supply a first calibration gas, a second calibration gas and a third calibration gas:
• a first metrology system including a first temperature sensor, a first pressure sensor and a first orifice having a first orifice size;
• a reference metrology system including a second temperature sensor, a second pressure sensor and a second orifice having the first orifice size;
• a controlled heating source configured to heat the first temperature sensor and the second temperature sensor;
• a controller configured to:
• a) cause the controlled heating source to heat the first temperature sensor and the second temperature sensor to a plurality of temperatures in a predetermined operating temperature range;
• b) cause a first transfer function to be generated based on first and second temperatures sensed by the first and second temperature sensors, respectively;
• c) cause the first calibration gas to be supplied at a plurality of pressures in a predetermined pressure range and a second transfer function to be generated based on first and second pressures sensed by the first and second pressure sensors, respectively;
• d) cause a first plurality of flow rate measurements to be performed in a predetermined flow rate range with the first metrology system and the reference metrology system, wherein the first metrology system and the reference metrology system use the first calibration gas;
• and
• e) cause temperature and pressure to be calibrated using the first transfer function and the second transfer function, respectively, and a corresponding transfer function to be determined for the first calibration gas based on the first plurality of flow rate measurements.