A reference volume for use with pressure change flow rate measurement apparatus has an internal structure comprising elements with cross section and length comparable to the cross section and length of adjacent interstitial fluid regions. The reference volume may have one or more heat conduction elements exterior to and in good thermal contact with a corrosion resistant material that defines the internal fluid holding region.

An electronic device manufacturing system includes: a gas supply; a mass flow controller (MFC) coupled to the gas supply; an inlet coupled to the MFC; an outlet; a control volume serially coupled to the inlet to receive a gas flow; and a flow restrictor serially coupled to the control volume and the outlet. A controller is adapted to allow the gas supply to flow gas through the control volume and the flow restrictor to achieve a stable pressure in the control volume, terminate the gas flow from the gas supply, and measure a rate of pressure decay in the control volume over time. A process chamber is coupled to a flow path, which is coupled to the mass flow controller, the process chamber to receive one or more process chemistries via the mass flow controller.

An electronic device manufacturing system includes: a gas supply; a mass flow controller (MFC) coupled to the gas supply; an inlet coupled to the MFC; an outlet; a control volume serially coupled to the inlet to receive a gas flow; and a flow restrictor serially coupled to the control volume and the outlet. A controller is adapted to allow the gas supply to flow gas through the control volume and the flow restrictor to achieve a stable pressure in the control volume, terminate the gas flow from the gas supply, and measure a rate of pressure decay in the control volume over time. A process chamber is coupled to a flow path, which is coupled to the mass flow controller, the process chamber to receive one or more process chemistries via the mass flow controller.

A gas supply system capable of flow measurement includes a flow controller that controls the flow rate of a flowing gas, a first shutoff valve provided downstream of the flow controller, a second shutoff valve provided in a first flow passage communicating with the downstream side of the first shutoff valve, a second flow passage that branches from the first flow passage, a third shutoff valve provided in the second flow passage, a pressure sensing device that detects a pressure in a flow passage controlled by the first, second, and third shutoff valves, a temperature sensing device that detects a temperature in the flow passage controlled by the first, second, and third shutoff valves, a volume measuring tank connected downstream of the third shutoff valve and having a known volume, and an arithmetic and control unit that obtains a passage volume controlled by the first, second, and third shutoff valves by applying Boyle's law to open and closed states of the third shutoff valve and calculates the flow rate of the flow controller, using the passage volume and detection values obtained by the pressure sensing device and the temperature sensing device.

A gas supply system capable of flow measurement includes a flow controller that controls the flow rate of a flowing gas, a first shutoff valve provided downstream of the flow controller, a second shutoff valve provided in a first flow passage communicating with the downstream side of the first shutoff valve, a second flow passage that branches from the first flow passage, a third shutoff valve provided in the second flow passage, a pressure sensing device that detects a pressure in a flow passage controlled by the first, second, and third shutoff valves, a temperature sensing device that detects a temperature in the flow passage controlled by the first, second, and third shutoff valves, a volume measuring tank connected downstream of the third shutoff valve and having a known volume, and an arithmetic and control unit that obtains a passage volume controlled by the first, second, and third shutoff valves by applying Boyle's law to open and closed states of the third shutoff valve and calculates the flow rate of the flow controller, using the passage volume and detection values obtained by the pressure sensing device and the temperature sensing device.

A pressure-type flow rate control device 1, while maintaining an upstream pressure P1 of an orifice 5 at approximately at least twice a downstream pressure P2, calculates a flow factor FF of a mixed gas consisting of two types of gases mixed at a mixture ratio of X:(1X) by FF=(k/){2/(+1)}.sup.1/(1)[/{(+1)R}].sup.1/2 using an average density , an average specific heat ratio , and an average gas constant R of the mixed gas that are calculated by weighting the densities, specific heat ratios, and gas constants of the two types of gases at the mixture ratio, and calculates a flow rate Q of the mixed gas passing through the orifice by Q=FF.Math.S.Math.P.sub.1(1/T.sub.1).sup.1/2, where S is the orifice cross section, and P.sub.1 and T.sub.1 are respectively the pressure and temperature of the mixed gas on the upstream side of the orifice.

A pressure-type flow rate control device 1, while maintaining an upstream pressure P1 of an orifice 5 at approximately at least twice a downstream pressure P2, calculates a flow factor FF of a mixed gas consisting of two types of gases mixed at a mixture ratio of X:(1X) by FF=(k/){2/(+1)}.sup.1/(1)[/{(+1)R}].sup.1/2 using an average density , an average specific heat ratio , and an average gas constant R of the mixed gas that are calculated by weighting the densities, specific heat ratios, and gas constants of the two types of gases at the mixture ratio, and calculates a flow rate Q of the mixed gas passing through the orifice by Q=FF.Math.S.Math.P.sub.1(1/T.sub.1).sup.1/2, where S is the orifice cross section, and P.sub.1 and T.sub.1 are respectively the pressure and temperature of the mixed gas on the upstream side of the orifice.

The pressure-type flow rate control device includes: a restriction part interposed in a flow channel; an upstream-side pressure sensor detecting a fluid pressure on the upstream side of the restriction part; a downstream-side pressure sensor detecting a fluid pressure on the downstream side of the restriction part; a flow control valve provided in the flow channel on the upstream side of the upstream-side pressure sensor; and computation control circuit controlling the flow control valve based on detected values of the upstream-side pressure sensor and the downstream-side pressure sensor, thereby controlling the flow. Under conditions where no fluid flow occurs in the flow channel, the computation control circuit computes the difference between the detected value of the upstream-side pressure sensor and the detected value of the downstream-side pressure sensor, and outputs a signal for pressure sensor malfunction determination based on the computed difference.

The pressure-type flow rate control device includes: a restriction part interposed in a flow channel; an upstream-side pressure sensor detecting a fluid pressure on the upstream side of the restriction part; a downstream-side pressure sensor detecting a fluid pressure on the downstream side of the restriction part; a flow control valve provided in the flow channel on the upstream side of the upstream-side pressure sensor; and computation control circuit controlling the flow control valve based on detected values of the upstream-side pressure sensor and the downstream-side pressure sensor, thereby controlling the flow. Under conditions where no fluid flow occurs in the flow channel, the computation control circuit computes the difference between the detected value of the upstream-side pressure sensor and the detected value of the downstream-side pressure sensor, and outputs a signal for pressure sensor malfunction determination based on the computed difference.

A substrate processing system includes a gas supply unit having a first gas flow channel. A second gas flow channel of a flow rate measurement system is connected to the first gas flow channel. The flow rate measurement system further includes a third gas flow channel connected to the second gas flow channel, and a pressure sensor and a temperature sensor that measure a pressure and a temperature, respectively, in the third gas flow channel. In a method, a flow rate of a gas output from a flow rate controller of the gas supply unit is calculated using a build-up method. The flow rate of a gas is calculated without using the total volume of the first gas flow channel and the second gas flow channel and temperatures in the first gas flow channel and the second gas flow channel.