Pressure type flow control system with flow monitoring, and method for detecting anomaly in fluid supply system and handling method at abnormal monitoring flow rate using the same

Abstract

A pressure type flow control system with flow monitoring includes an inlet, a control valve including a pressure flow control unit connected downstream of the inlet, a thermal flow sensor connected downstream of the control valve, an orifice installed on a fluid passage communicatively connected downstream of the thermal flow sensor, a temperature sensor provided near the fluid passage between the control valve and orifice, a pressure sensor provided for the fluid passage between the control valve and orifice, an outlet communicatively connected to the orifice, and a control unit including a pressure type flow rate arithmetic and control unit receiving a pressure signal from the pressure sensor and a temperature signal from the temperature sensor, and a flow sensor control unit to which a flow rate signal from the thermal flow sensor is input.

Claims

1. A pressure type flow control system with flow monitoring, comprising: (a) an inlet side passage for fluid; (b) a control valve and a valve drive unit of a pressure type flow control unit that is connected to a downstream side of the inlet side passage; (c) a thermal type flow sensor that is connected to a downstream side of the control valve; (d) an orifice that is installed on a first fluid passage communicatively connected to a downstream side of the thermal type flow sensor; (e) a temperature sensor that is provided near the first fluid passage between the control valve and the orifice to measure temperature of fluid in the first fluid passage; (f) a pressure sensor that is provided for the first fluid passage between the control valve and the orifice to measure pressure of fluid in the first fluid passage; (g) an outlet side passage that is communicatively connected to the orifice; and (h) a first control unit comprising (i) a pressure type flow rate arithmetic and control unit to which a pressure signal from the pressure sensor and a temperature signal from the temperature sensor are input, and the pressure type flow rate arithmetic and control unit computes a first flow rate value Q of fluid flowing through the orifice based on the input pressure signal, and the pressure type flow rate arithmetic and control unit outputs a control signal Pd for performing a feedback control to the valve drive unit that brings the control valve into an opening or closing action in a direction in which a difference between the computed first flow rate value and a set flow rate value is decreased; and (ii) a flow sensor control unit to which a flow rate signal from the thermal type flow sensor is input, and the flow sensor control unit computes a second flow rate of the fluid flowing through the orifice according to the flow rate signal to indicate an actual flow rate of the fluid flowing through the orifice, wherein, when a difference between the first flow rate of the fluid computed by the flow sensor control unit and the second flow rate of the fluid computed by the pressure type flow rate arithmetic and control unit exceeds a set value, then the first control unit performs an alarm indication; wherein the control valve is a nearest control valve to the orifice on an upstream side, and there are no other control valves between the control valve and the orifice.

2. The pressure type flow control system with flow monitoring according to claim 1, wherein the pressure sensor is provided between an outlet side of the control valve and an inlet side of the thermal type flow sensor.

3. The pressure type flow control system with flow monitoring according to claim 2, wherein when a difference between the first flow rate of the fluid computed by the flow sensor control unit and the second flow rate of the fluid computed by the pressure type flow rate arithmetic and control unit exceeds a set value, then the first control unit performs an alarm indication.

4. The pressure type flow control system with flow monitoring according to claim 1, wherein the control valve, the thermal type flow sensor, the orifice, the pressure sensor, the temperature sensor, the inlet side passage, and the outlet side passage, are integrally assembled in one body, and the first fluid passage is integrally formed in the one body.

5. The pressure type flow control system with flow monitoring according to claim 1, wherein the pressure sensor is provided between the thermal flow type sensor and the orifice.

6. A pressure type flow control system with flow monitoring, comprising: (a) an inlet side passage for fluid; (b) a control valve and a valve drive unit of a pressure type flow control unit that is connected to a downstream side of the inlet side passage; (c) a thermal type flow sensor that is connected to a downstream side of the control valve; (d) an orifice that is installed on a first fluid passage communicatively connected to a downstream side of the thermal type flow sensor; (e) a temperature sensor that is provided near the first fluid passage between the control valve and the orifice to measure temperature of fluid in the first fluid passage; (f) a first pressure sensor that is provided for the first fluid passage between the control valve and the orifice to measure pressure of fluid in the first fluid passage; (g) an outlet side passage that is communicatively connected to the orifice; and (h) a control unit comprising (i) a pressure type flow rate arithmetic and control unit to which pressure signals from the first pressure sensor and a temperature signal from the temperature sensor are input, and the pressure type flow rate arithmetic and control unit monitors critical expansions conditions of fluid flowing through the orifice and computes a first flow rate value Q of the fluid flowing through the orifice based on the input pressure signal, and the pressure type flow rate arithmetic and control unit outputs a control signal Pd for performing a feedback control to the valve drive unit that brings the control valve into an opening or closing action in a direction in which a difference between the computed first flow rate value and a set flow rate value is decreased; and (ii) a flow sensor control unit to which a flow rate signal from the thermal type flow sensor is input, and the flow sensor control unit computes a second flow rate of the fluid flowing through the orifice according to the flow rate signal to indicate an actual flow rate of the fluid flowing through the orifice, wherein, when a difference between the first flow rate of the fluid computed by the flow sensor control unit and the second flow rate of the fluid computed by the pressure type flow rate arithmetic and control unit exceeds a set value, then the first control unit performs an alarm indication; wherein the control valve is a nearest control valve to the orifice on an upstream side, and there are on other control valves between the control valve and the orifice.

7. The pressure type flow control system with flow monitoring according to claim 6, wherein the first control unit performs an alarm indication when the fluid flowing through the orifice is out of the critical expansion conditions.

8. The pressure type flow control system with flow monitoring according to claim 6, wherein the control valve, the thermal type flow sensor, the orifice, the first pressure sensor, the temperature sensor, the inlet side passage, and the outlet side passage, are integrally assembled in one body, and the first fluid passage is integrally formed in the one body.

9. The pressure type flow control system with flow monitoring according to claim 6, wherein a second pressure sensor is provided for the outlet side passage on the downstream side of the orifice to measure pressure of fluid on the downstream side of the orifice, and wherein the control unit further comprises the second pressure sensor.

10. The pressure type flow control system with flow monitoring according to claim 9, wherein the control valve, the thermal type flow sensor, the orifice, the first pressure sensor, the temperature sensor, the inlet side passage, the outlet side passage, and the second pressure sensor, are integrally assembled in one body, and the first fluid passage is integrally formed in the one body.

11. The pressure type flow control system with flow monitoring according to claim 6, wherein the pressure sensor is provided between the thermal flow type sensor and the orifice.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a configuration of a pressure type flow control system with flow monitoring utilizing an orifice according to an embodiment of the present invention.

(2) FIG. 2 is a schematic diagram of a configuration showing another example of a pressure type flow control system with flow monitoring, in accordance with another embodiment of the present invention.

(3) FIG. 3 is a schematic diagram of a configuration showing yet another example of the pressure type flow control system with flow monitoring.

(4) FIG. 4 is an explanatory diagram of a configuration of a thermal type flow sensor.

(5) FIG. 5 is an explanatory diagram of the principle of operation of the thermal type flow sensor.

(6) FIG. 6 is a first conception diagram of the pressure type flow control system with flow monitoring, which is conceived by the inventors of the present application.

(7) FIG. 7 is a second conception diagram of the pressure type flow control system with flow monitoring, which is conceived by the inventors of the present application.

(8) FIG. 8 shows curves of the step response characteristics of a thermal type flow sensor (in the case of a set flow rate of 20%).

(9) FIG. 9 shows curves of the step response characteristics of the thermal type flow sensor (in the case of a set flow rate of 50%).

(10) FIG. 10 shows curves of the step response characteristics of the thermal type flow sensor (in the case of a set flow rate of 10%).

(11) FIG. 11 shows curves of the monitoring flow rate accuracy characteristics of the thermal type flow sensor (in the case of a set flow rate of 100% to 97%).

(12) FIG. 12 shows curves of the monitoring flow rate accuracy characteristics of the thermal type flow sensor (in the case of a set flow rate of 20.0% to 19.4%).

(13) FIG. 13 shows curves of the supply pressure fluctuating characteristics of the thermal type flow sensor (in the case of a set flow rate of 50%).

(14) FIG. 14 shows curves of the repetitive reproducibility characteristics of the thermal type flow sensor (in the case of a set flow rate of 100%).

(15) FIG. 15 shows curves of the repetitive reproducibility characteristics of the thermal type flow sensor (in the case of a set flow rate of 20%).

(16) FIG. 16 is a configuration diagram of a pressure type flow control system using an orifice.

(17) FIG. 17 is an explanatory diagram of a configuration of a mass flow control system according to a first embodiment disclosed by Japanese Patent No. 4137666.

(18) FIG. 18 is an explanatory diagram of a configuration of a mass flow control system according to a second embodiment disclosed by Japanese Patent No. 4137666.

(19) FIG. 19 is a block configuration diagram showing an example of a fluid supply system used for an embodiment of the present invention according to a method for detecting an anomaly.

(20) FIG. 20 is a flow diagram showing an example of a method for detecting anomalies in valves of the fluid supply system according to the present invention.

(21) FIG. 21, comprised of FIG. 21A and FIG. 21B in an exploded view over two pages to allow for legibility, shows the relationship between types of faults, genesis phenomena, and causes of occurrence at flow rate self-diagnosis.

(22) FIG. 22 shows a representative example of pressure drop characteristics as graphed in the case of insufficient supply pressure at flow rate self-diagnosis of the pressure type flow control system with flow monitoring.

(23) FIG. 23(a) shows a representative example of pressure drop characteristics as graphed in the event of a fault of a driving mechanism of an air-operated valve on the secondary side.

(24) FIG. 23(b) shows a representative example of pressure drop characteristics as graphed in the case where there is a leakage from the outside to the secondary side.

(25) FIG. 24(a) shows a representative example of pressure drop characteristics as graphed in the case where gas at a high flow factor is mixed in.

(26) FIG. 24(b) shows a representative example of pressure drop characteristics as graphed in the case where gas at a low flow factor is mixed in.

(27) FIG. 25(a) shows a representative example of pressure drop characteristics as graphed in the case where an orifice is clogged.

(28) FIG. 25(b) shows a representative example of pressure drop characteristics as graphed in the case where the orifice expands.

(29) FIG. 26 shows a representative example of pressure drop characteristics as graphed in the case where there is a seat leakage in a control valve of the pressure type flow control system with flow monitoring.

(30) FIG. 27 shows a representative example of pressure drop characteristics, as graphed, in the case where there is a fault of a drive unit of the control valve of the pressure type flow control system with flow monitoring.

(31) FIG. 28 shows a representative example of pressure drop characteristics as graphed at the time of zero-point fluctuation of the pressure type flow control system with flow monitoring.

(32) FIG. 29 shows the four types of pressure drop characteristics, which are derived from the patterns of the respective pressure drop characteristics of FIG. 21 to FIG. 26.

(33) FIG. 30 is a flow diagram showing an example of a handling method when a monitoring flow rate of the pressure type flow control system with flow monitoring is abnormal.

(34) FIG. 31 is a schematic block configuration diagram showing an example of a fluid supply system equipped with a pressure type flow control system with flow monitoring in a semiconductor manufacturing facility.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(35) Hereinafter, an embodiment of a pressure type flow control system with flow monitoring, according to the present invention, will be described with reference to the drawings. In the drawings, like parts are designated by like character references. FIG. 1 is a schematic diagram of a configuration according to an embodiment of a pressure type flow control system 1 with flow monitoring according to the present invention. The pressure type flow control system 1 with flow monitoring is composed of a pressure type flow control unit 1a and a thermal type flow monitoring unit 1b.

(36) Furthermore, the pressure type flow control unit 1a is composed of a control valve 3a, a temperature sensor 4, a pressure sensor 5, an orifice 6, and a pressure type flow rate arithmetic and control unit 7a forming a component of a control unit 7.

(37) Moreover, the thermal type flow monitoring unit 1b is composed of a thermal type flow sensor 2 and a flow sensor control unit 7b forming another component of the control unit 7.

(38) The pressure type flow control unit 1a, as described above, is composed of the control valve 3, the temperature sensor 4, the pressure sensor 5, the orifice 6, the pressure type flow rate arithmetic and control unit 7a, and the like, and a flow rate setting signal is output from an input terminal 7a.sub.1, and a flow rate output signal of a fluid flowing through the orifice, which has been computed by the pressure type flow control unit 1a, is output from an output terminal 7a.sub.2.

(39) The pressure type flow control unit 1a itself, which uses the orifice 6, is a publicly-known technique as evident from Japanese Patent No. 3291161, and the like, and computes a flow rate of fluid flowing through the orifice 6 under the critical expansion conditions on the basis of pressure detected by the pressure detection sensor 5, with the pressure type flow rate arithmetic and control unit 7a, and outputs a control signal Pd proportional to a difference between the set flow rate signal input from the input terminal 7a.sub.1 and the computed flow rate signal outputted to a valve drive unit 3a of the control valve 3.

(40) Because the configurations of the pressure type flow control unit 1a and the flow rate arithmetic and control unit 7a thereof are substantially the same as those described in FIG. 16, detailed descriptions thereof are here omitted. Furthermore, as a matter of course, various types of ancillary mechanisms, such as the publicly-known zero-point adjustment mechanism and flow rate anomaly detection mechanism, and a gaseous species conversion mechanism (F. F. value conversion mechanism), are provided in the pressure type flow control unit 1a. Moreover, in FIG. 1, reference symbol 8 denotes an inlet side passage, reference symbol 9 denotes an outlet side passage, and reference symbol 10 denotes a fluid passage in the device main body.

(41) The thermal type flow monitoring unit 1b composing the pressure type flow control system 1 with flow monitoring is composed of the thermal type flow sensor 2 and the flow sensor control unit 7b, and an input terminal 7b.sub.1 and an output terminal 7b.sub.2 are respectively provided for the flow sensor control unit 7b. Then, a setting signal within a flow rate range to be monitored is input from the input terminal 7b.sub.1, and a monitoring flow rate signal (i.e., a real flow rate signal) detected by the thermal type flow sensor 2 is output from the output terminal 7b.sub.2.

(42) Furthermore, although not shown in FIG. 1, as a matter of course, input and output of the monitoring flow rate signal and a computed flow rate signal are appropriately carried out between the flow sensor control unit 7b and the pressure type flow rate arithmetic and control unit 7a, and a difference between them both, and a level of the difference, may be monitored. Alternatively, a warning may be issued in the case where the difference between both the monitoring flow rate signal and the computed flow rate signal exceeds a given value.

(43) FIG. 2 shows another example of the pressure type flow control system 1 with flow monitoring, which is configured to detect fluid pressure between the control valve 3 and the thermal type flow sensor 2 using the pressure sensor 5. In addition, other configurations and operations of the pressure type flow control system 1 with flow monitoring are completely the same as those in the case of the embodiment illustrated by FIG. 1.

(44) FIG. 3 shows yet another example of the pressure type flow control system 1 with flow monitoring, in accordance with the present invention, in which a pressure sensor 17 is separately installed on the downstream side of the orifice 6. This embodiment makes it possible to monitor whether or not the fluid flowing through the orifice 6 is under the critical expansion conditions, to issue an alarm, or to perform flow control by use of differential pressure between the pressure sensor 5 and the pressure sensor 17.

(45) The thermal type flow monitoring unit 1b is composed of the thermal type flow sensor 2 and the flow sensor control unit 7b, and FIG. 4 and FIG. 5 show an outline of the configuration of the thermal type flow monitoring unit 1b. That is, as shown in FIG. 4, the thermal type flow sensor 2 has a bypass pipe group 2d (i.e., a laminar flow element) and a sensor pipe 2e which bypasses the bypass pipe group 2d. A gas fluid of a small quantity, compared to the bypass pipe group 2d, is made to flow through the sensor pipe 2e at a constant ratio. Furthermore, a pair of resistance wires R1 and R4 for control, which are series-connected, are rolled around the sensor pipe 2e to output a flow rate signal 2c indicating a mass flow rate value that is monitored by a sensor circuit 2b connected to the resistance wires R1 and R4.

(46) The flow rate signal 2c is introduced into the flow sensor control unit 7b composed of, for example, a microcomputer or the like, to determine the real flow rate (i.e., the actual flow rate) of a currently flowing fluid on the basis of the flow rate signal 2c.

(47) FIG. 5 illustrates a basic structure of the sensor circuit 2b of the thermal type flow sensor 2, and the series-connected circuits of two standard resistors R2 and R3 are connected in parallel to the series-connection of the resistance wires R1 and R4 described above, so as to form a bridge circuit. A constant current source is connected to this bridge circuit, and a connecting point between the resistance wires R1 and R4, and a connecting point between the standard resistors R2 and R3, are connected to the input side, to provide a differential circuit, which is configured to determine a potential difference between these two connecting points and to output this potential difference as the flow rate signal 2c.

(48) In addition, because the thermal type flow sensor 2 and the flow sensor control unit 7b themselves are publicly known devices, detailed descriptions thereof are here omitted. Furthermore, in the present embodiment, a sensor mounted in the FCS-T1000 series manufactured by Fujikin Incorporated is used as the thermal type flow monitoring unit 1b.

(49) Next, an embodiment of the invention, pertaining to a method for detecting an anomaly in a fluid supply system using the pressure type flow control system 1 with flow monitoring, will be described. Referring to FIG. 1, the pressure type flow control unit 1a of the pressure type flow control system with flow monitoring has a configuration substantially equivalent to a conventional pressure type flow control system FCS shown in FIG. 16, and a flow rate setting circuit (not shown) corresponding to a flow rate setting mechanism and a pressure indicating mechanism (not shown) corresponding to a pressure indicating mechanism, a flow rate output circuit (not shown) indicating a flow rate, and the like, are provided in the pressure type flow control unit 1a. Furthermore, a so-called flow rate self-diagnostic mechanism (not shown) is provided in the pressure type flow control unit 1a, which is, as will be described later, configured to compare initially set pressure drop characteristics and pressure drop characteristics at diagnosis, to judge or ascertain an abnormal state, and output its judgment or determination as a result.

(50) Moreover, a mechanism of transmitting a signal of insufficient supply pressure is provided in the pressure type flow control unit 1a for the case where supply pressure from the gas supply source to the control valve 3 is insufficient. In this way, a signal is provided to indicate when it becomes not possible to supply a gas flow rate at the set flow rate, or when it becomes not possible to maintain the critical expansion conditions.

(51) FIG. 19 shows an example of a fluid supply system using the pressure type flow control system with flow monitoring, which is an objective to be implemented by the present invention. The fluid supply system is composed of a purge gas supply system Y, a process gas supply system X, the pressure type flow control system 1 with flow monitoring, a process gas using system C, and the like.

(52) Furthermore, at the time of using the fluid supply system, usually, first, an inert gas such as N.sub.2 or Ar is, as a purge gas Go, made to flow from the purge gas supply system Y to the pipe passage 8, to the pressure type flow control system 1 with flow monitoring, and to the pipe passage 9, and the like, to purge the inside of the fluid supply system. Thereafter, a process gas Gp is supplied in place of the purge gas Go, and the process gas Gp is supplied to the process gas using system C while regulating its flow rate to a desired flow rate in the pressure type flow control system 1 with flow monitoring. In addition, in FIG. 19, reference symbols V.sub.1, V.sub.2 and V.sub.3 are valves, such as automatic opening/closing valves equipped with fluid pressure drive units and electromotive drive units.

(53) The valves inspected by use of the present invention are the valves V.sub.1, V.sub.2 and V.sub.3 in FIG. 19, and the like, and so-called seat leakages and operational anomalies in the valves V.sub.1, V.sub.2 and V.sub.3 are inspected during preparation for starting to supply a process gas to a process chamber E or during preparation for stopping the supply of the process gas, or the like, by use of the pressure type flow control system with flow monitoring (hereinafter called the pressure type flow control unit 1a).

(54) In more detail, the operational anomalies in the respective valves V.sub.1, V.sub.2 and V.sub.3 are inspected in accordance with the following steps by use of the pressure type flow control unit 1a (i.e., the pressure type flow control system FCS).

(55) A: Operational Anomaly in Valve V.sub.1: a. A predetermined live gas (e.g., a process gas Gp) is made to circulate or flow, and the gas is made to circulate or flow at a predetermined set flow rate by the FCS. At this time, in the case where a flow rate indicated value and a pressure indicated value (in the pipe passage 8 and/or the pipe passage 9) of the FCS change to 0, then there is an anomaly (malfunction) in operation of the valve V.sub.1. b. A predetermined live gas (process gas Gp) is made to circulate or flow in the FCS, and in the case where an error signal of insufficient supply pressure is transmitted from the FCS during diagnosis (hereinafter called a flow rate self-diagnosis for live gas) with respect to whether or not the live gas controlled flow rate of the FCS is a predetermined flow rate, then there is an anomaly (malfunction) in operation of the valve V.sub.1.

(56) B: Operational Anomaly in Valve V.sub.2: a. N.sub.2 is made to circulate as a purge gasGo, and this purge gas is made to circulate or flow at a predetermined set flow rate by the FCS. At this time, in the case where a flow rate indicated value and a pressure indicated value of the FCS change to 0, then there is an anomaly (malfunction) in operation of the valve V.sub.2. b. A N.sub.2 gas is made to circulate or flow in the FCS, and in the case where an error signal of insufficient supply pressure is transmitted from the FCS during diagnosis (hereinafter called at flow rate self-diagnosis for N.sub.2) with respect to whether or not the N.sub.2 controlled flow rate of the FCS is a predetermined flow rate, then there is an anomaly (malfunction) in operation of the valve V.sub.3.

(57) C: Operational Anomaly in Valve V.sub.3: a. In the case where an error signal of flow rate self-diagnosis is transmitted from the FCS, a flow rate self-diagnosis for N.sub.2 or at flow rate self-diagnosis for live gas under the condition that N.sub.2, or the live gas, is made to flow, then there is an anomaly (malfunction of the valve V.sub.2) b. In the case where the pressure output indication of the FCS does not drop to zero at the time of vacuuming a pipe passage 9b, and the like, then there is an anomaly (malfunction) in operation of the valve V.sub.3. c. In the case where there is no change in the pressure indicated value of the FCS even when the flow rate set value is appropriately changed at the time of setting the flow rate of the FCS, then there is an operational anomaly (malfunction) in the valve V.sub.3.

(58) Furthermore, the seat leakages in the respective valves V.sub.1, V.sub.2 and V.sub.3 are inspected in accordance with the following steps by use of the FCS.

(59) A: Seat leakage in valve V.sub.1: a. When there is a seat leakage in the valve V.sub.1 at flow rate self-diagnosis of the FCS with N.sub.2, the N.sub.2 flows back toward the live gas Gp side, and the live gas Gp on the upstream side of the valve V.sub.1 becomes a mixed gas of the N.sub.2 and the live gas Gp.
Thereafter, when the flow rate self-diagnosis for live gas of the FCS is executed, the flow rate self-diagnosis for live gas is performed with the mixed gas, and the diagnosed value becomes an abnormal value. Due to this diagnosed value becoming an abnormal value, it becomes apparent that there is a seat leakage in the valve V.sub.1.

(60) More specifically, in the case of a flow factor F. F. of the live gas (process gas Gp)>1, the diagnostic result is deviated to the side (minus side), and in the case of a flow factor F. F. of the live gas (process gas Gp)<1, the diagnostic result is deviated to the + side (plus side).

(61) In addition, the flow factor F. F. is a value indicating how many times by the standard gas (N.sub.2) that the live gas flow rate is multiplied in the case where the orifice of the FCS, and the pressure P.sub.1 on the upstream side of the orifice, are the same. Thus, the value defined by F. F.=live gas flow rate/N.sub.2 flow rate (e.g., refer to Japanese Published Unexamined Patent Application No. 2000-66732, and the like, such as equivalent U.S. Pat. No. 6,314,992 B1 that is incorporated herein by reference).

(62) B. Seat leakage in valve V.sub.2. In the case where the diagnosed value of the flow rate self-diagnosis for live gas is an abnormal value, then a seat leakage is detected in the valve V.sub.2. Because the N.sub.2 gas is mixed into the live gas Gp of the pipe passage 8 on the upstream side of the FCS, and the flow rate self-diagnosis for live gas is performed with the mixed gas in the FCS, the diagnosed value becomes an abnormal value.

(63) C. Seat leakage in valve V.sub.3. After the completion of flow control by the FCS, the valve V.sub.3 is maintained in a closed state, and the flow rate setting of the FCS is set to 0 (i.e., the flow rate is set to zero). Thereafter, when the pressure indicated value of the FCS drops, a seat leakage is detected in the valve V.sub.3.

(64) By carrying out the respective operations by use of the FCS as described above, it is possible to detect operational anomalies and seat leakages in the valves V.sub.1, V.sub.2 and V.sub.3 by use of the FCS in the fluid supply system having the configuration of FIG. 19.

(65) In addition, in the embodiment of FIG. 19, the fluid supply system equipped with three valves is an object to which the present invention is applied. Meanwhile, as a matter of course, the present invention is applicable even when the number of the process gas supply systems Y is more than one, or even when the number of the process gas using systems C is more than one.

(66) FIG. 20 illustrates a flow diagram in the case where anomalies in the respective valves V.sub.1, V.sub.2 and V.sub.3 of the fluid supply system shown in FIG. 19 are checked. In addition, this flow diagram is premised on the presumption that there are no external leakages (for example, leakages from joints, hoods, and the like) other than seat leakages in valve V.sub.1 when determining whether there is a seat leakage in valve V.sub.1. It is also presumed that the respective valves V.sub.1, V.sub.2 and V.sub.3, the FCS, and the pipe passages 8, 9, 9b, and the like, have no external leakages other than seat leakages in valve V.sub.2, and the drive units of the respective valves function normally function when determining whether there is a seat leakage in valve V.sub.2. It is further presumed that the FCS functions normally, and that the V.sub.1 and V.sub.2 valves are not simultaneously opened in any case, and the like, in FIG. 19.

(67) First, according to the flow diagram of FIG. 20, an anomaly check is started in Step S.sub.0. Next, in Step S.sub.1, operations of closing the valve V.sub.1, opening to closing (switching) the valve V.sub.2, closing the valve V.sub.3, and opening the FCS control valve are carried out, and the pipe passage 9 on the downstream side of the FCS is filled with N.sub.2.

(68) In Step S.sub.2, the pressure indication P.sub.1 of the FCS, i.e., the pressure indication P.sub.1 of the pressure sensor 1a in FIG. 1 is checked, to judge or ascertain whether or not an increase and decrease P.sub.1 of P.sub.1 is 0.

(69) In the case where the P.sub.1 is not 0, and the P.sub.1 rises, it is judged or determined that one or both of the valves V.sub.1 and V.sub.2 are abnormal (e.g., have seat leakages or operational defects). Furthermore, in the case where the P.sub.1 is not 0 and the P.sub.1 is decreased, it is judged or determined that the valve V.sub.3 is abnormal (i.e., valve V.sub.3 has a seat leakage or an operational defect) (Step S.sub.3).

(70) Next, in Step S.sub.4, after vacuuming the insides of the pipe passages by closing the valve V.sub.1, closing the valve V.sub.2, opening the valve V.sub.3, and opening the FCS control valve, the process gas (live gas) Gp is made to flow in the FCS by opening the valve V.sub.1 and closing the valve V.sub.2, and the pressure indication P.sub.1 of the FCS is checked in Step S.sub.5. It is judged or determined that the operation of valve V.sub.1 is normal when the P.sub.1 rises (Step S.sub.7), and it is judged or determined that the valve V.sub.1 is abnormal in operation when the P.sub.1 does not rise (Step S.sub.6), in order to check the operating status of the valve V.sub.1.

(71) Thereafter, in Step S.sub.8, after vacuuming the insides of the pipe passages by closing the valve V.sub.1, closing the valve V.sub.2, opening the valve V.sub.3, and opening the FCS control valve, wherein the pressure indication P.sub.1 of the FCS is checked by closing the valve V.sub.1 and opening the valve V.sub.2 (Step S.sub.9). It is judged or ascertained that valve V.sub.2 is abnormal in operation when the P.sub.1 does not rise (Step S.sub.10), in order to check the operating status of the valve V.sub.2. Further, it is judged or ascertained that the operation of the valve V.sub.2 is normal when the P.sub.1 rises (Step S.sub.11).

(72) Next, in Step S.sub.12, it is judged or determined whether or not the anomalies in the valves in the Step S.sub.2 correspond to an anomaly in operation of the valve V.sub.3. That is, it is judged or determined that valve V.sub.3 is abnormal in operation when the judgment or determination in Step S.sub.2 is No (i.e., any one of the valves V.sub.1, V.sub.2 and V.sub.3 is abnormal in operation) and the operations of the valves V.sub.1 and V.sub.2 are normal (Step S.sub.13). Furthermore, it is judged or determined that the operations of the respective valves V.sub.1, V.sub.2 and V.sub.3 are normal when the judgment or determination in Step S.sub.2 is Yes (Step S.sub.14).

(73) Next, the check for seat leakages in the respective valves V.sub.1, V.sub.2 and V.sub.3 is carried out. That is, in Step S.sub.15, after vacuuming the insides of the pipe passages by closing the valve V.sub.1, closing the valve V.sub.2, opening the valve V.sub.3, and opening the control valve 3 of the FCS, by closing the valve V.sub.1, opening to closing (switching) the valve V.sub.2, and closing the valve V.sub.3 in the same way as in Step S.sub.1, the pipe passage 9b between the FCS and the valve V.sub.3 is pressurized so as to keep the pressure indication P.sub.1 of the FCS (that is, keep the pressure between the control valve 3 and the valve V.sub.3).

(74) In Step S.sub.16, decompression of the P.sub.1 is checked, and when there is decompression, it is judged or ascertained that there is a seat leakage in the valve V.sub.3 (Step S.sub.17). Furthermore, when there is no decompression, it is judged or determined that there is no seat leakage in the valve V.sub.3 (Step S.sub.18).

(75) Next, in Step S.sub.19, after vacuuming the insides of the pipe passages by closing the valve V.sub.1, closing the valve V.sub.2, opening the valve V.sub.3, and opening the control valve 3 of the FCS, the pipe passages 8, 9 and 9b are decompressed (vacuumed) by closing the valve V.sub.1, closing the valve V.sub.2, and opening the valve V.sub.3, and thereafter the valve V.sub.3 is closed (Step S.sub.20). Thereafter, the pressure indication P.sub.1 of the FCS is checked in Step S.sub.21, and when the pressure indication P.sub.1 is not increased in pressure, it is judged or determined that there is no seat leakage in the valves V.sub.1 and V.sub.2 in Step S.sub.22, and the anomaly check is completed (Step S.sub.31).

(76) Furthermore, when the pressure indication P.sub.1 is increased in pressure in Step S.sub.21, it is judged that there is a seat leakage in one of the valves V.sub.1 and V.sub.2 (Step S.sub.23), and the algorithm or flow diagram proceeds to the process of judging or determining in which valve there is a seat leakage.

(77) In Step S.sub.24, after vacuuming the insides of the pipe passages by closing the valve V.sub.1, closing the valve V.sub.2, opening the valve V.sub.3, and opening the control valve 3 of the FCS, by opening the valve V.sub.1 and closing the valve V.sub.2, a flow rate self-diagnosis for live gas of the pressure type flow control system 1 with flow monitoring is carried out. That is, the pressure drop characteristics when the live gas (process gas Gp) is made to flow and the initial set pressure drop characteristics are compared, and when a difference between the pressure drop characteristics and the initial set pressure drop characteristics is an allowable value or lower, it is judged or ascertained that there is no anomaly in the diagnosed value. Furthermore, in contrast, in the case where the difference between the pressure drop characteristics and the initial set pressure drop characteristics is higher than the allowable value, it is judged or ascertained that there is an anomaly in the diagnosed value.

(78) In Step S.sub.24, when there is no anomaly in the diagnosed value, it is judged or ascertained that there is a seat leakage only in the valve V.sub.1 (Step S.sub.26). This is because, even when there is a seat leakage in the valve V.sub.1, when there is no seat leakage in the valve V.sub.2, a fluid flowing into the pressure type flow control system 1 with flow monitoring (FCS) is only the process gas Gp. Accordingly, no anomaly is caused in the diagnosed value of the flow rate self-diagnosis for live gas.

(79) On the other hand, in the case where there is an anomaly in the diagnosed value in Step S.sub.24, the valve V.sub.1 is closed and the valve V.sub.2 is opened, to carry out a flow rate self-diagnosis for N.sub.2 of the pressure type flow control system 1 with flow monitoring in Step S.sub.27. That is, the pressure drop characteristics when the N.sub.2 gas is made to flow and the initial pressure drop characteristics are compared, and when a difference between both the pressure drop characteristics when the N.sub.2 gas is made to flow and the initial pressure drop characteristics is an allowable value or lower, it is diagnosed that there is no anomaly in the diagnosed value. Furthermore, in the case where the difference between both the pressure drop characteristics when the N.sub.2 gas is made to flow and the initial pressure drop characteristics is higher than the allowable value, it is diagnosed that the diagnosed value is abnormal.

(80) In Step S.sub.28, when there is no anomaly in the diagnosed value of the flow rate self-diagnosis for N.sub.2, it is judged or ascertained that there is a seat leakage only in the valve V.sub.2 in Step S.sub.29. This is because, when there is a seat leakage in the valve V.sub.1, the live gas is mixed into the N.sub.2, so as to cause an anomaly in the diagnosed value of the flow rate self-diagnosis for the FCS.

(81) In contrast, in Step S.sub.28, in the case where there is an anomaly in the diagnosed value of the flow rate self-diagnosis for N.sub.2, a seat leakage is present in the valve V.sub.1, and a mixed gas of the N.sub.2 and the live gas flows into the FCS, so as to cause an anomaly in the diagnosed value. Consequently, in Step S.sub.303 it is judged or determined that seat leakages are caused in both of the valves V.sub.1 and V.sub.2.

(82) In addition, in the anomaly check flow diagram of FIG. 20, there is a flow of the algorithm in that, after detecting anomalies in the valves V.sub.1, V.sub.2 and V.sub.3 in Step S.sub.3, operational anomalies and seat leakage anomalies in the respective valves V.sub.1, V.sub.2 and V.sub.3 are sequentially checked. However, when an anomaly is detected in Step S.sub.3, it may be first determined whether the type of the anomaly is an operational anomaly or a seat leakage in a valve from a fluctuation level of the anomaly, and when the type of the anomaly is an operational anomaly, Step S.sub.4 to Step S.sub.13 may be executed. And, when the type of the anomaly is a seat leakage anomaly, Step S.sub.15 to Step S.sub.30 may be executed, respectively.

(83) Furthermore, with respect to the determination of the operational anomaly, it is possible to judge or ascertain from the pace of increase in the pressure indication P.sub.1 or the pace of decrease in the pressure indication P.sub.1 in Step S.sub.3. When the pace of increase in the pressure indication P.sub.1 is high, it is possible to judge or ascertain an anomaly in opening/closing of the valve, and when the pace of increase in the pressure indication P.sub.1 is low, it is possible to judge or ascertain a seat leakage anomaly in the valve.

(84) Next, the relationship between the pressure drop characteristics at flow rate self-diagnosis and a cause of anomaly, and the like, in the case where a result of the flow rate self-diagnosis is judged or ascertained as abnormal has been verified. In addition, the flow rate self-diagnosis is, as described above, used to compare the initial set pressure drop characteristics and the pressure drop characteristics at diagnosis, and to judge or determine as abnormal in the case where a difference between the initial set pressure drop characteristics and the pressure drop characteristics at diagnosis is out of a range determined in advance.

(85) First, the inventors configured a basic fluid supply system as shown in FIG. 19, and caused a fault (i.e., an anomaly) in a simulating manner, and then surveyed the pressure drop characteristics associated with the respective anomalies. Furthermore, the inventors analyzed the relationship between the obtained pressure drop characteristics and its occurrence factors in order to find the existence of a close constant relationship between the pattern of pressure drop characteristics and the corresponding cause of the anomaly occurrence. In other words, the inventors found, via simulations, that it is possible to know the cause of an anomaly occurrence if a pattern of pressure drop characteristics at the time of the anomaly occurrence becomes apparent.

(86) FIG. 21, comprised of FIG. 21A and FIG. 21B in an exploded view over two pages to allow for legibility, shows that the relationships between various specific types of faults A (identification of faults), which are caused in a simulated manner at flow rate self-diagnosis, and phenomena B that are caused by the faults A, and general factors C pertaining to the faults that directly lead to the genesis of phenomena B, may be surveyed. FIG. 21 constitutes a compilation of these relationships as a chart. Furthermore, the numerical values 1 to 4 in the fields regarding the patterns of pressure drop characteristics indicate the types of the patterns of the pressure drop characteristics that are respectively caused with respect to the specific types of faults A, as will be described later.

(87) FIG. 22 to FIG. 28 show the pressure drop characteristics at flow rate self-diagnosis corresponding to cases where the respective specific faults shown in FIG. 21 are caused and, respectively, the horizontal axis shows the time, and the vertical axis shows the detection pressures of the pressure type flow control unit 1a, i.e., the FCS. That is, in FIG. 22, the control pressure is insufficient at the time of maintaining a flow rate of 100%, due to insufficient supply pressure from the gas supply source side, and the pattern of pressure drop characteristics becomes a pattern of the type 4, which will be described later.

(88) In FIG. 23(a), the pressure on the secondary side of the orifice rises because of a fault pertaining to air operation of the air operated valve V.sub.3 on the secondary side (i.e., the output side of the FCS). As a result, a pressure drop delays in the process of diagnosis (and becomes a pattern of Type 2). Furthermore, in FIG. 23(b), the pressure on the secondary side of the orifice rises because a leaked gas flows into the secondary side from the outside on the secondary side of the orifice. Thus, the pattern of the pressure drop characteristics becomes the pattern of Type 2, which is the same pattern as that in the case of FIG. 23(a).

(89) In FIG. 24(a), because gas at a high flow factor (F. F.) flows into the primary side of the pressure type control unit 1a, i.e., the FCS, it becomes easy to increasingly outgas from a throttle mechanism (orifice), as a result, a pressure drop in the pressure drop characteristics accelerates (thereby exhibiting a pattern of Type 3). In contrast, in FIG. 24(b), because gas at a low flow factor (F. F.) flows into the primary side of the FCS, it becomes difficult to outgas from the throttle mechanism (orifice), and a pressure drop in the pressure drop characteristics delays (thereby exhibiting the pattern of Type 1). In addition, the throttle mechanism is explained with the orifice in the following description.

(90) In FIG. 25(a), because the orifice is clogged, it becomes difficult to outgas from the orifice, and a pressure drop in the pressure drop characteristics delays (thereby exhibiting the pattern of Type 1). In contrast, in FIG. 25(b), because the orifice is expanded in diameter (e.g., such as may occur due to flow erosion of the opening of the orifice due to the flow of gas through the orifice), it becomes easy to outgas from the orifice, and a pressure drop accelerates (thereby exhibiting the pattern of Type 3).

(91) In FIG. 26, because a seat leakage is caused in the control valve 3, gas flows from the control valve 3 during a flow rate self-diagnosis, and the pressure drop in the pressure drop characteristics delays (thereby exhibiting the pattern of Type 1).

(92) In FIG. 27, because there is an anomaly in a transmission system of the drive unit of the control valve 3, the control valve does not open smoothly. Consequently, a seat leakage occurs. As a result, supply of gas is not carried out and the gas does not flow, therefore, the pressure drop characteristics are not changed (thus, the pattern of Type 4 is exhibited).

(93) FIG. 28 shows the case where the zero-point adjustment of the pressure type flow control unit 1a goes out of order. When the zero-point is fluctuated on the plus side, the pressure drop delays so the pattern of Type 1 is exhibited. Furthermore, when the zero-point is fluctuated on the minus side, the pressure drop accelerates, and the pressure drop characteristics thereof become those of the pattern of Type 3. Thus, in accordance with this disclosure, a zero-point fluctuation on the side of plus corresponds to pressure drop delays, and a zero-point fluctuation of the side of minus corresponds to pressure drop acceleration. Moreover, a minus fluctuation of the zero-point and a plus fluctuation of the zero-point are phenomena that can cause problems in any device such as a pressure sensor, a control unit 1a, and a monitoring unit 1b.

(94) FIG. 29 collectively shows the various patterns of the different types of the pressure drop characteristics exhibited at the flow rate self-diagnosis as shown in FIG. 22 to FIG. 28.

(95) Thus, in accordance with the present disclosure, the pressure drop characteristics are roughly classified into patterns of four types, which are summarized below according to the following Types 1 to 4.

(96) Pressure drop characteristics of Type 1 (Pressure drop delays immediately after diagnosis): This pattern is caused in the case of a fault, such as interfusion of gas at a low flow factor, product adhesion/dust clogging of the orifice, dust jamming in the control valve, product adhesion (seat leakage), or a plus fluctuation of the zero-point.

(97) Pressure drop characteristics of Type 2 (Pressure drop delays in the process of diagnosis): This pattern is caused in the case of a fault of the air-operated mechanism of the valve on the secondary side, or due to a fault of a leakage from the outside to the secondary side, or the like.

(98) Pressure drop characteristics of Type 3 (Pressure drop accelerates immediately after diagnosis): This pattern is caused in the case of a fault, such as interfusion of gas at a high flow factor, inappropriate input of zero-point, clogging of the hole (orifice) due to corrosion, breakage of an orifice plate, or a minus fluctuation of the zero-point.

(99) Pressure drop characteristics of Type 4 (The flow rate does not reach 100% at initial diagnosis): This pattern is caused in the case of insufficient supply pressure, a fault of the air-operated mechanism on the primary side, dust clogging (of a prefilter), an anomaly in the transmission system of the drive unit of the control valve (i.e., a fault of the control valve), or the like.

(100) As is clear from the descriptions of FIG. 21 and FIG. 22 to FIG. 29, in accordance with the present invention, by reviewing which one of the Types 1 to 4 a pattern of pressure drop characteristics occurring at a flow rate self-diagnosis corresponds to, it is possible to easily determine the cause of the fault and its place of occurrence, which makes it possible to efficiently and swiftly repair (or inspect) the gas supply system.

(101) Next, when a seat leakage, or the like, is caused in a valve of the fluid supply system, or some fault is caused in the pressure type flow control system 1 itself, provided with flow monitoring 1, it becomes apparent that there is an anomaly in a monitoring flow rate occurring at the flow rate self-diagnosis. Thus, it is determined, in accordance with the present invention, whether the anomaly in the monitoring flow rate is caused by an anomaly in the fluid supply system, or by an anomaly in the pressure type flow control system 1 itself. When a fault, or the like, in the pressure type flow control system 1 is the cause of the anomaly in the monitoring flow rate, it is necessary to swiftly replace the pressure type flow control system 1.

(102) Therefore, in accordance with the present invention, when an anomaly in monitoring flow rate appears, first, as shown by the algorithm diagram of FIG. 30, a flow rate self-diagnosis of the pressure type flow control system 1 with flow monitoring is performed (Step 40). In addition, the method of flow rate self-diagnosis is the same as the method described by FIG. 20, and the like. Furthermore, it has become apparent that the anomaly in monitoring flow rate is generally caused by such anomalies as a shift in zero-point of the thermal type flow monitoring unit 1b shown in FIG. 1, a shift in zero-point of the pressure type flow control unit 1a, an anomaly in the fluid supply system, a fault of the pressure type flow control system 1 itself that is provided with flow monitoring, and the like.

(103) A flow rate self-diagnosis is performed in Step 40 and a result thereof is diagnosed in Step 41, and when the result of the flow rate self-diagnosis is within a normal range determined in advance (i.e., OK), a zero-point adjustment of the thermal type flow sensor 2 is carried out in Step 42. Thereafter, a monitoring flow rate output is again checked in Step 43, and when the output of the flow rate is within the normal range determined in advance in Step 44, this is judged as usable (i.e., OK), which is continuously provided for use.

(104) When the result of the flow rate self-diagnosis is out of the set range in Step 41 (i.e., a not good or NG determination is made), a cause of the anomaly in monitoring flow rate in the flow rate self-diagnosis is analyzed in Step 45, in order to understand and ascertain the cause of the anomaly in the monitoring flow rate.

(105) The factorial analysis of the anomaly of the flow rate self-diagnosis is carried out is Step 45 according to the descriptions of FIG. 21 to FIG. 29, and it is judged or determined which type of the four types, Types 1 to 4, corresponds to the cause of the anomaly.

(106) Furthermore, in the flow rate self-diagnosis of the pressure type flow control system with flow monitoring, in the case where it is judged or ascertained that the cause of the anomaly in flow rate is caused by a change in bore of the orifice according to a pattern of the pressure drop characteristic curve (i.e., in the case of Type 1 of FIG. 25(a) and Type 2 of FIG. 25(b)), an output value of the flow rate from the pressure type flow control system with flow monitoring may be calibrated so as to consider the monitoring flow rate as the correct value (i.e., the actual flow rate as determined by flow rate measurement). In addition, as a calibration method for the output value of the flow rate from the pressure type flow control system provided with flow monitoring, for example, a method for appropriately selecting about 5 to 10 points as flow rate detecting points is employed, in order to perform calibration by use of differences between the corresponding monitoring flow rate values at these respective points and the flow rate output value.

(107) Next, first in Step 46, it is checked as to whether or not there is a shift in the zero-point of the pressure sensor, and when there is no shift in the zero-point of the pressure sensor, it is checked whether or not this corresponds to an anomaly in the fluid supply system in Step 47. In contrast, when it becomes apparent that there is a shift in the zero-point of the pressure sensor in Step 46, the zero-point of the pressure sensor is adjusted in Step 48 and, thereafter, the processing is again returned to Step 40, in order to execute another flow rate self-diagnosis.

(108) In Step 47, is checked whether or not the cause of the anomaly corresponds to the anomaly in the fluid supply system, and in the case where this does not correspond to an anomaly in the fluid supply system, it is judged or determined that there is a cause of the anomaly in the monitoring flow rate in the pressure type flow control system itself that is provided with flow monitoring. When this judgment or determination is made, then handling of replacement and/or exchange of the pressure type flow control system with flow monitoring with a new pressure type flow control system with flow monitoring is carried out. Furthermore, in Step 47, in the case where it becomes apparent that the cause of the anomaly corresponds to an anomaly in the fluid supply system in Step 47, the fluid supply system is repaired or restored in Step 49, and, thereafter, the processing is again returned to Step 40, to execute another flow rate self-diagnosis.

INDUSTRIAL APPLICABILITY

(109) The present invention is widely applicable not only to gas supplying facilities for semiconductor manufacturing equipment, but also generally to fluid supply facilities using pressure type flow control systems provided with flow monitors having pressure sensors in the chemical industry, the food industry, and the like. Thus, while making full use of the excellent flow control characteristics of a pressure type flow control system using an orifice, and with simple addition, it is possible to easily and precisely, and appropriately monitor a real flow rate of a controlled fluid in real time, and it is possible to precisely judge or ascertain, as a result of a flow rate self-diagnosis, whether an anomaly in the pressure type flow control system provided with flow monitoring is caused by the pressure type flow control system itself in order to conduct appropriate swift handling of the anomaly when a monitoring flow rate is abnormal. Thus, in accordance with the present invention, when broadly construed, a pressure type flow control system provided with flow monitoring is constructed to include an inlet side passage 8 for fluid, a control valve 3 comprising a pressure type flow control unit 1a that is connected to a downstream side of the inlet side passage 8, a thermal type flow sensor 2 that is connected to a downstream side of the control valve 3, an orifice 6 that is installed along the way of a fluid passage 10 communicatively connected to a downstream side of the thermal type flow sensor 2, a temperature sensor 4 that is provided near the fluid passage 10 between the control valve 3 and the orifice 6, a pressure sensor 5 that is provided for the fluid passage 10 between the control valve 3 and the orifice 6, an outlet side passage 9 that is communicatively connected to the orifice 6, and a control unit 7 that is comprised of a pressure type flow rate arithmetic and control unit 7a to which a pressure signal from the pressure sensor 5 and a temperature signal from the temperature sensor 4 are input, and computes a flow rate value Q of a fluid flowing through the orifice 6, and outputs a control signal Pd to a valve drive unit 3a for bringing the control valve 3 into an opening or closing action in a direction in which a difference between the computed flow rate value and a set flow rate value is decreased, and a flow sensor control unit 7b to which a flow rate signal 2c from the thermal type flow sensor 2 is input, and computes a flow rate of the fluid flowing through the orifice 6 according to the flow rate signal 2c, to indicate the actual flow rate.

DESCRIPTION OF REFERENCE SYMBOLS

(110) 1: Pressure type flow control system with flow monitoring

(111) 1a: Pressure type flow control unit

(112) 1b: Thermal type flow monitoring unit

(113) 2: Thermal type flow sensor

(114) 2b: Sensor circuit

(115) 2d: Bypass pipe group

(116) 2e: Sensor pipe

(117) 3: Control valve

(118) 3a: Valve drive unit

(119) 4: Temperature sensor

(120) 5: Pressure sensor

(121) 6: Orifice

(122) 7: Control unit

(123) 7a: Pressure type flow rate arithmetic and control unit

(124) 7b: Flow sensor control unit

(125) 7a.sub.1: Input terminal

(126) 7a.sub.2: Output terminal

(127) 7b.sub.1: Input terminal

(128) 7b.sub.2: Output terminal

(129) 8: Inlet side passage

(130) 9: Outlet side passage

(131) 10: Fluid passage in device main body

(132) 11: Gas supply source

(133) 12: Pressure regulator

(134) 13: Purge valve

(135) 14: Input side pressure sensor

(136) 15: Data logger

(137) 16: Vacuum pump

(138) 17: Pressure sensor

(139) Pd: Control valve control signal

(140) Pc: Flow rate signal

(141) A.sub.1: Flow rate setting input

(142) A.sub.2: Flow rate output of pressure type flow control system

(143) B.sub.1: Output from thermal type flow sensor (FIG. 6: In the case of thermal type flow sensor on the primary side)

(144) B.sub.2: Output from thermal type flow sensor (FIG. 7: In the case of thermal type flow sensor on the secondary side)

(145) X: Process gas supply system

(146) X.sub.1: Pipe

(147) Y: Purge gas supply system

(148) Y.sub.1: Pipe

(149) C: Process gas using system

(150) E: Process chamber

(151) FCS: Pressure type flow control system

(152) V.sub.1 to V.sub.3: Valve

(153) Go: Purge gas

(154) Gp: Process gas