JP2004246825A - Mass flow controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mass flow controller which can perform flow control with a wide dynamic range. <P>SOLUTION: The mass flow controller has an opening control valve 4 which controls the flow of fluid passing in a channel 2; a pressure sensor 7b disposed on the downstream side of the control valve 4, a throttling part 6 disposed on the downstream side of the pressure sensor 7b; a flow sensor 5 which measures the flow rate F of the fluid passing in the channel 2; and a control unit 8 which controls the flow rate F of the fluid passing through the throttling part 6 by controlling the control value 4 using the output Spb of the pressure sensor 7b when controlling a large flow rate, and at the same time controls the flow rate F of the fluid passing through flow sensor 5 by controlling the opening/closing of the control valve 4 by using the output of the flow sensor 5 when controlling a small flow rate, thereby permitting flow rate control with a wide dynamic range. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mass flow controller. More specifically, the present invention relates to a mass flow controller having a wide dynamic range.
[0002]
[Prior art]
FIG. 4 is a diagram showing an example of a semiconductor manufacturing line 10 using a conventional mass flow controller. In FIG. 4, reference numeral 11 denotes a chamber constituting a semiconductor manufacturing line, and reference numerals 12a and 12b denote gas supply lines for supplying gases G having different flow control ranges to the chamber 11 (in this example, the gas supply line 12b is branched from the gas supply line 12b). 13 is a gas cylinder for supplying gas G.
[0003]
Each gas supply line 12a is provided with a mechanical pressure regulator 14, a gauge 15 downstream of the pressure regulator 14, and a filter 16, and each of the branched gas supply lines 12a, 12b has a mass flow controller 17a, 17b and pneumatic on-off valves 18a to 18d. That is, the mass flow controllers 17a and 17b can be replaced by closing the pneumatic on-off valves 18a to 18d, and the flow rate is controlled by selectively opening and closing the pneumatic on-off valves 18a and 18c or the pneumatic on-off valves 18b and 18d. The configuration is such that the mass flow controllers 17a and 17b used for switching can be switched.
[0004]
The pressure of the gas G supplied from the cylinder 13 is normally reduced to about 98 kPa at the outlet side, but the pressure is reduced to, for example, about 30 kPa by the pressure regulator 14 and supplied to the mass flow controllers 17a and 17b. This prevents the mass flow controllers 17a and 17b from being damaged. Further, the administrator of the semiconductor manufacturing line controls the mass flow controllers 17a and 17b so that a predetermined flow rate of the gas G flows into the chamber 11, and adjusts the pressure regulator 14 while checking the gauge 15 to control the mass flow controllers 17a and 17b. The pressure of the supplied gas G is appropriately adjusted.
[0005]
As shown in FIG. 4, by using the two mass flow controllers 17a and 17b, for example, a small flow rate control of, for example, 10 mL / min to 500 mL is performed using the mass flow controller 17a, and 500 mL to 500 mL using the mass flow controller 17a. By performing a flow control of a large flow rate of 50 L / min, a flow control of a wide dynamic range of 10 mL / min to 50 L / min is performed as a whole.
[0006]
By using the gas supply panel having the above configuration, for example, when a process gas is flowed as the gas G, a flow rate control of a small flow rate of about several tens of mL / min is performed using the mass flow controller 17a, and when a purge gas is flowed as the gas G, The mass flow controller 17b controls the flow rate of a large flow rate of about several L / min.
[0007]
[Problems to be solved by the invention]
However, when the two mass flow controllers 17a and 17b are used, it is inevitable that the gas supply lines 12a and 12b become complicated. In other words, the ordinary mass flow controllers 17a and 17b control the flow rate by, for example, combining a thermal flow rate sensor and an open / close control valve and using the output of the flow rate sensor to feed back the flow rate. If it exceeds the range, the output will not be obtained due to saturation, so that this dynamic range has been suppressed to about 50 times. For this reason, it was not possible to control the flow rates of both the process gas and the purge gas, which led to a complicated and large line.
[0008]
In addition, the more complicated the gas supply lines 12a and 12b, the more complicated the control becomes, and the higher the occurrence rate of gas leakage and failure is unavoidable. Further, since it is necessary to switch the gas supply lines 12a and 12b, there is a problem that the flow rate control cannot be performed continuously, and there is also a problem that the gas stays in the plurality of gas supply lines 12a and 12b.
[0009]
Therefore, in order to obtain a wide dynamic range, it is considered to use a special mass flow controller that obtains a dynamic range of about 500 times in a gas supply line of a semiconductor process. However, such a conventional special mass flow controller is used. Even so, sufficient dynamics could not be obtained in the gas supply line of the semiconductor process.
[0010]
In addition, since the pressure regulator 14 for pressure adjustment and pressure fluctuation countermeasures is provided on the primary side of the mass flow controllers 17a and 17b as described above, the number of parts must be increased, and the gas supply panel must be increased. Could not be reduced.
[0011]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mass flow controller capable of controlling a flow rate in a wide dynamic range.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a mass flow controller according to a first aspect of the present invention includes an opening / closing control valve for controlling a flow of a fluid flowing in a flow path, a pressure sensor disposed downstream of the opening / closing control valve, A restrictor disposed on the downstream side, a flow sensor for measuring the flow rate of the fluid flowing through the flow path, and a fluid flowing through the restrictor by controlling the on / off control valve using the output of the pressure sensor during large flow control. Control that controls the flow rate of the fluid flowing through the flow sensor by controlling the opening and closing of the open / close control valve using the output of the flow sensor during low flow rate control. And a part. (Claim 1)
[0013]
Therefore, by performing the pressure control on the upstream side of the throttle unit by the opening / closing control of the opening / closing control valve using the output of the pressure sensor, it is possible to control the large flow rate of the fluid flowing through the mass flow controller. Further, by controlling the opening / closing of the opening / closing control valve using the output of the flow sensor, a small flow rate of the fluid flowing through the flow sensor can be controlled. In other words, the control unit controls the flow rate using different methods for the small flow rate control and the large flow rate control, thereby controlling the flow rate in a wide dynamic range from a small flow rate to a large flow rate, which was impossible in the past. Can do it. In addition, at the time of the small flow rate control, the flow rate of the fluid flowing through the throttle section is small, so that the throttle section does not hinder the flow rate control.
[0014]
In the case where the flow sensor is provided in the flow path on the upstream side of the on-off control valve (claim 2), the inside of the flow sensor is evacuated even when the secondary side of the mass flow controller is evacuated. Since the flow rate sensor does not malfunction, the reliability is improved.
[0015]
A mass flow controller according to a second aspect of the present invention includes a first opening / closing control valve for controlling a flow of a fluid flowing in a flow path, a pressure sensor disposed downstream of the first opening / closing control valve, and a downstream side of the pressure sensor. A second on-off control valve disposed on the side, a flow sensor for measuring the flow rate of the fluid flowing through the flow path, and the second on-off control valve being fully opened at the time of large flow rate control, and using the output of the pressure sensor. The flow rate of the fluid flowing through the flow rate sensor is controlled by controlling the flow rate of the fluid by controlling the flow rate of the fluid by controlling the flow rate of the fluid by controlling the flow rate of the fluid by controlling the flow rate of the fluid by controlling the flow rate of the fluid. And a control unit that controls a flow rate to enable a flow rate control with a wide dynamic range. (Claim 3)
[0016]
Therefore, it is possible to control the large flow rate of the fluid flowing through the mass flow controller by opening and closing the second opening / closing control valve and controlling the opening / closing of the first opening / closing control valve using the output of the pressure sensor. At this time, a flow rate control of a large flow rate is performed by using a resistance (a functioning portion as a restrictor) formed in the flow path by the second opening / closing control valve and / or the flow rate sensor which has been fully opened and a pressure at an upstream side thereof. Can be. Further, by controlling the opening / closing of the second opening / closing control valve using the output of the flow sensor, it is possible to control the small flow rate of the fluid flowing through the flow sensor. In other words, the control unit controls the flow rate using different methods for the small flow rate control and the large flow rate control, thereby controlling the flow rate in a wide dynamic range from a small flow rate to a large flow rate, which was impossible in the past. Can do it.
[0017]
The flow rate sensor is provided between a first opening / closing control valve and a second opening / closing control valve, and the control section controls opening / closing of the first opening / closing control valve by using an output of the pressure sensor at the time of low flow rate control. In the case where the control for stabilizing the pressure of the fluid flowing into the flow rate sensor is performed (claim 4), the flow rate control with a small flow rate is particularly controlled without being affected by the pressure fluctuation in the primary side flow path at all. Can be done with precision.
[0018]
Further, in any of the first and second inventions, when the pressure sensor is provided in the flow path on the downstream side of the flow sensor (claim 5), the pressure drop caused by the flow resistance of the flow sensor is reduced. This does not affect the accuracy of the flow control at the time of the large flow control.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing an example of the mass flow controller 1 of the present invention. The mass flow controller 1 of the present embodiment includes a flow path block 3 forming a flow path 2 for flowing a fluid (a gas is exemplified as a fluid in the following example, but the fluid is not limited to a gas). An opening / closing control valve 4 connected to the flow path block 3, a flow sensor 5, a throttle section 6, two pressure sensors 7, a control section 8 for controlling the opening / closing control valve 4, and a filter 9. are doing.
[0020]
The flow path 2 is formed, for example, so as to hollow out the inside of the flow path block 3, and has a first flow path 2a and a second flow path 2b. Further, pipe attachment portions 3a and 3b are provided at the upstream end and the downstream end of the flow path 2, respectively. The flow path 2 may be formed by excavation, by using a mold, or by another method. When the second flow path 2b is formed by excavation or the like, a flow path block is formed. 3 needs to be formed in at least one place so as to be separable, but in any case, gas leakage can be prevented by integrally molding the flow path blocks 3, 3a, 3b.
[0021]
The opening / closing control valve 4 includes, for example, a diaphragm 4a abutting on a valve seat 3c formed on one side surface of the flow path block 3 and an actuator 4b thereof. The degree is configured to be controllable.
[0022]
The flow sensor 5 includes, for example, a rectifier 5a inserted into the second flow path 2b, a branch flow path 5b that branches from the second flow path 2b by a flow rate of a predetermined ratio 1 / A, and a flow path 5b. And a flow path signal Sf indicating the total flow rate F.
[0023]
The throttle unit 6 is, for example, a sonic nozzle that flows a fluid having a flow rate corresponding to the pressure on the primary side when the pressure difference between the primary side and the secondary side is equal to or greater than a predetermined value. The block in which the throttle portion 6a is formed is arranged on the downstream end side of the flow path 2b so as to communicate with the flow path 2b. In the present invention, the throttle section 6 is not limited to a sonic nozzle, but may be any as long as the throttle section 6a for forming a resistance in the flow path 2 is formed.
[0024]
The opening / closing control valve 4 and the flow sensor 5 are arranged side by side on one side surface (upper surface) of the flow path block 3, so that the overall size of the mass flow controller 1 can be reduced.
[0025]
The pressure sensor 7 includes a first sensor 7a disposed on a side surface facing the first flow path 2a and a second sensor 7b disposed on a side surface facing the second flow path 2b. The pressure sensors 7a and 7b are provided on a surface different from the side surface on which the components 4 to 5 are attached (in this example, a first surface located in front of the first flow path 2a and a position located immediately before the rectifier 5a constituting the flow sensor 5 in FIG. 1). (Back of two flow paths). Thereby, the pressure sensor 7 can be installed without changing the overall size of the mass flow controller 1. The sensors 7a and 7b output pressure signals Spa and Spb indicating the pressures Pa and Pb in the first flow path 2a and the second flow path 2b, respectively.
[0026]
In this example, the sensors 7a and 7b are provided on the side surfaces. However, the mounting surface of the pressure sensor 7 is not limited as long as the pressure sensor 7 can be mounted so as to face the flow path 2. In other words, it goes without saying that the control valve 4 and the flow rate sensor 5 may be embedded in the lower surface of the flow path block 3 or at a position where they do not interfere with the flow sensor 5.
[0027]
The control unit 8 outputs the opening control signal C by feeding back the pressure signals Spa and Spb (output) from the pressure sensor 7 and the flow control signal Sf (output) from the flow sensor 5, thereby opening and closing the control valve. 4 has a processing unit 8a for performing feedback control of the control unit 4 and an external interface 8b.
[0028]
Although not shown, the mass flow controller 1 of this example has a display unit for displaying values F, Pa, and Pb measured by the sensors 5, 7a, and 7b. Further, the values F, Pa, Pb measured by the sensors 5, 7a, 7b can be output to the outside via the interface 8b. In this example, for ease of understanding, an example is shown in which the interface 8b inputs and outputs analog values, but this may be digital communication.
[0029]
In addition, the open / close control of the open / close control valve 4 is not limited to the feedback control using only the output signal Spb of the pressure sensor 7b, and may be controlled using the output signal Spa of the pressure sensor 7a. By providing the pressure sensor 7a as shown in this example, it is possible to monitor the pressure of the gas input to the mass flow controller 1, but it is also possible to omit the pressure sensor 7a. Not even.
[0030]
Further, since the mass flow controller 1 of the present embodiment has the built-in filter 9, there is no need to connect and connect a separate filter 16 unlike the conventional case. That is, the gas supply line can be simplified accordingly, and the installation area can be reduced. In this example, an example is shown in which the filter 9 is provided at the most upstream end of the flow path 2 to prevent a malfunction due to entry of foreign matter, but the present invention does not limit the position of the filter 9. In some cases, the filter 9 can be omitted.
[0031]
In the mass flow controller 1 having the above-described configuration, the processing unit 8a sets a predetermined threshold value for the flow rate setting signal Fs input via the interface 8b, and determines whether the flow rate setting signal Fs is a small flow rate setting or a large flow rate setting. Is determined, and the control method for performing feedback control of the opening / closing control valve 4 during the large flow rate control and the small flow rate control is changed. Accordingly, the present invention provides a simple configuration of a mass flow controller having a wide dynamic range.
[0032]
That is, for example, when the flow rate setting signal Fs is a voltage signal in the range of 0 to 5 V, the processing unit 8a sets, for example, 4 V as the predetermined threshold value, and sets the input flow rate setting signal Fs to 0 to 4 V (the predetermined threshold value). The flow rate control is performed as a small flow rate control in the case of (less than) and a large flow rate control in a range of 4 to 5 V (not less than a predetermined threshold). The processing unit 8a (control unit 8) uses the output (pressure signal Spb) of the pressure sensor 7b to feed back the on-off control valve 4 to control the opening and closing of the valve when the large flow rate is controlled, thereby flowing through the sonic nozzle 6. On the other hand, the flow rate F of the fluid flowing through the flow rate sensor 5 is controlled by controlling the open / close control valve 4 by using the output (flow rate signal Sf) of the flow rate sensor 5 to feed back the open / close control valve 4 during the low flow rate control. Is controlled.
[0033]
The shape of the throttle portion 6a of the sonic nozzle 6 is such that the fluid can flow even at a maximum flow rate of, for example, about 50 L / min, and by reducing the pressure Pb adjusted by the pressure sensor 7b. For example, the flow rate can be controlled up to about 500 mL / min. The flow sensor 5 can measure the flow rate of a fluid flowing at a flow rate of about 10 mL / min to 500 mL / min.
[0034]
Therefore, during the small flow rate control, the opening / closing control valve 4 is fed back using the flow rate signal Sf measured by the flow rate sensor 5 to adjust the magnitude of the opening degree control signal C, whereby the fluid flowing through the flow rate sensor 5 is adjusted. Can be controlled with high accuracy at a small flow rate F of, for example, about 10 mL / min to 500 mL / min. The controller 8 monitors the pressure Pa at the most upstream portion and the pressure Pb downstream of the flow sensor 5 during the low flow rate control, so that when the gas pressure supplied to the upstream side of the mass flow controller 1 fluctuates. It is also possible to adjust the opening control signal C so as to cancel the disturbance of the flow rate at the time.
[0035]
On the other hand, at the time of the large flow rate control, the opening / closing control valve 4 is fed back using the pressure signal Spb measured by the pressure sensor 7b to adjust the magnitude of the opening degree control signal C to thereby reduce the fluid flowing through the sonic nozzle 6. For example, a high flow rate F of about 500 mL / min to 50 L / min can be controlled with high accuracy.
[0036]
In other words, the mass flow controller of this embodiment performs flow control in a wide dynamic range from 10 mL / min to 50 L / min by changing the control method for performing feedback control of the on-off control valve 4 during large flow control and small flow control. be able to.
[0037]
Therefore, there is no need to switch and use different mass flow meters 17a and 17b in accordance with the flow rate of the fluid as in the prior art, so that the supply line can be simplified and various problems caused by assembling a complicated supply line (reducing the equipment cost). Increases, an increase in the rate of occurrence of leaks, generation of stagnation, etc.) can be eliminated, and continuous flow control from a small flow rate to a large flow rate can be performed.
[0038]
The control range of the flow rate using the measurement value Sf of the flow rate sensor 5 and the control range of the flow rate using the measurement value Spb of the pressure sensor 7b are overlapped to use both the outputs Sf and Spb of the sensors 5 and 7b. Thus, it is also possible to output the open / close control signal C of the open / close control valve 4 using one output Sf or Spb, and confirm the operation using the other output Spb or Sf. Further, it is also possible to output the open / close control signal C of the open / close control valve 4 by weighting the values of the two outputs Sf and Spb according to the flow rate.
[0039]
In addition, in this example, in the integrated flow path block 3, the pressure sensor 7b faces the flow path 2b immediately before the sonic nozzle 6, and the pressure sensor 7b is provided in the flow path on the downstream side of the flow rate sensor 5. ing. Therefore, at the time of the large flow rate control, the flow rate F of the fluid flowing through the sonic nozzle 6 can be accurately controlled by performing the open / close control of the open / close control valve 4 using the pressure signal Spb of the pressure sensor 7b. At this time, even if the resistance generated by the rectifier 5a or the like constituting the flow rate sensor 5 may form a pressure difference between the temporary side and the secondary side of the rectifier 5a, this may cause an increase in the accuracy of the flow rate adjustment. No adverse effects.
[0040]
Further, as shown in this example, the opening / closing control valve 4 and the flow rate sensor 5 are arranged side by side, and the second flow path 2b located therebetween is made as short as possible. The time delay of the pressure Pb with respect to the output can be made as small as possible, and the fluctuation of the pressure Pb can be made as small as possible.
[0041]
Further, by arranging the pressure sensor 7b at a position as close to the flow sensor 5 as possible in the second flow path 2b between the opening / closing control valve 4 and the flow sensor 5 (flow path immediately preceding the flow sensor 5), the influence of turbulence and the like is obtained. Pressure Pb can be measured. That is, the control accuracy and stability of the flow rate by the mass flow controller 1 can be improved accordingly.
[0042]
In addition, by eliminating a joint or a pipe from the inside of the second flow path 2b between the opening / closing control valve 4 and the flow rate sensor 5, it is possible to eliminate the risk of pressure drop and gas leakage due to resistance of the flow path.
[0043]
FIG. 2 is a block diagram showing a modification of the mass flow controller 1. In FIG. 2, portions denoted by the same reference numerals as those in FIG. 1 are the same or equivalent portions, and thus detailed description thereof will be omitted. The example shown in this example differs from the example shown in FIG. 1 in that a flow rate sensor 5 is provided in the flow path 2 a on the upstream side of the on-off control valve 4.
[0044]
With the configuration as in the present example, even if the pressure on the secondary side of the mass flow controller 1 is reduced to a substantially vacuum state by a vacuum pump or the like, the inside of the flow sensor 5 disposed upstream of the on-off control valve 4 is not affected. Since there is no evacuation and fluid is present in the flow path sensor 5, the flow path sensor 5 does not malfunction. That is, the flow rate control can be performed without being affected by the decrease in the secondary pressure during the small flow rate control, and the reliability of the flow rate control can be improved accordingly.
[0045]
In the case of this example, the pressure Pa of the fluid supplied to the mass flow controller 1 can be obtained by disposing the pressure sensor 7a on the primary side of the flow sensor 5. That is, the control section 8 corrects the output (flow signal Sf) of the flow sensor 5 using the output (pressure signal Spa) of the pressure sensor 7a, thereby making it possible to reduce the influence of the fluctuation of the primary pressure. Thus, the flow rate control with higher accuracy can be performed.
[0046]
FIG. 3 is a diagram showing a further modified example of the mass flow controller 1. Also in FIG. 3, the portions denoted by the same reference numerals as those in FIGS. 1 and 2 are the same or equivalent portions, and thus redundant description will be avoided.
[0047]
The configuration of the mass flow controller 1 'of this example is such that the sonic nozzle 6 is removed from the configuration of the mass flow controller 1 shown in FIG. 1, and an opening / closing control valve 6' is further provided at this portion (at the downstream end of the second flow path). The second flow path 2b and the third flow path 2c communicate with each other in an openable and closable manner. That is, also in this example, the mass flow controller 1 'has the first opening / closing control valve 4 and the second opening / closing control valve 6'. The second opening / closing control valve 6 ′ includes, for example, a diaphragm 6 b abutting on a valve seat 3 d formed on one side surface of the flow path block 3 and an actuator 6 c thereof. The degree of opening for communicating and connecting 2c can be controlled.
[0048]
The control unit 8 in the mass flow controller 1 'configured as in the present example also provides a predetermined threshold value for the flow rate setting signal Fs input via the interface 8b, and determines whether the flow rate is small depending on whether the flow rate setting signal Fs is smaller or larger than the threshold value. The control method for performing feedback control of the open / close control valve 4 during the large flow rate control and the small flow rate control is determined by determining whether the setting is the setting of the flow rate or the setting of the large flow rate. That is, the present invention thereby provides a mass flow controller having a wide dynamic range and a simple configuration.
[0049]
Specifically, the control unit 8 (processing unit 8a) outputs an opening / closing control signal (flow control signal) Cf for bringing the second opening / closing control valve 6 'to a fully open state during large flow control, The output Spb of the pressure sensor 7b is used for feedback control, and an opening / closing control signal (pressure control signal) Cp for controlling the pressure Pb immediately above the flow rate sensor 5 is output to the first opening / closing control valve 4 to control the fluid. Control the flow rate. That is, at the time of the first flow rate control, the flow rate sensor 5 and the second opening / closing control valve 6 'are used as a so-called throttle which gives a predetermined resistance to the fluid, and the pressure Pb just above the throttles 5 and 6' is controlled to control the large flow rate. Is performed.
[0050]
On the other hand, at the time of low flow rate control, the control section 8 (processing section 8a) uses the output Spb of the pressure sensor 7b for feedback control, and sets the pressure Pb immediately above the flow rate sensor 5 to the first opening / closing control valve 4 to a constant value. An output (flow measurement value Sf) of the flow sensor 5 is used for feedback control in a state where the opening / closing control signal (pressure control signal) Cp for controlling the pressure is output to stabilize the pressure of the fluid supplied to the flow sensor 5. By controlling the opening / closing of the second opening / closing control valve 6 ′, the flow rate of the fluid flowing through the flow rate sensor 5 is controlled.
[0051]
That is, the flow control in a wide dynamic range from a small flow rate (for example, 10 mL / min) to a large flow rate (for example, 50 L / min) can be performed by one miniaturized mass flow controller 1 ′. Further, the mass flow controller 1 ′ of this example can stabilize the pressure Pb immediately above the flow rate sensor 5 by the output of the pressure control signal Cp to the first opening / closing control valve 4. It is possible to perform the flow control without being affected by the fluctuation.
[0052]
Further, since the flow rate sensor 5 is provided between the first opening / closing control valve 4 and the second opening / closing control valve 6 ', the control unit 8 uses the output of the pressure sensor 5 during the low flow rate control to perform the first By controlling the opening / closing of the open / close control valve, it is possible to perform control for stabilizing the pressure of the fluid flowing into the flow rate sensor. In addition to this, the flow sensor 5 is also controlled by the second on-off control valve 6 ′ to control the flow rate at a small flow rate while the evacuation is performed by a vacuum pump or the like on the downstream side of the mass flow controller 1 ′. The flow sensor 5 is separated from the flow path on the side, so that the inside of the flow sensor 5 does not enter a vacuum state. That is, the flow rate sensor 5 can control the flow rate without being affected by the pressure state on both the upstream side and the downstream side of the mass flow controller 1 ′.
[0053]
As described above, the present invention has a very wide dynamic range and is capable of performing high-precision flow control, despite being a mass flow controller having a simple structure.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a mass flow controller of the present invention.
FIG. 2 is a diagram showing a modification of the mass flow controller.
FIG. 3 is a diagram showing another example of the mass flow controller.
FIG. 4 is a diagram showing an example of a semiconductor manufacturing line using a conventional mass flow controller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Mass flow controller, 2 ... Flow path, 4 ... Open / close control valve (first open / close control valve), 5 ... Flow rate sensor, 6 ... Second open / close control valve, 7b ... Pressure sensor, 8 ... Control part.

Claims (5)

An on-off control valve for controlling the flow of a fluid flowing in the flow path;
A pressure sensor arranged downstream of the on-off control valve,
A restrictor disposed downstream of the pressure sensor;
A flow sensor for measuring the flow rate of the fluid flowing through the flow path,
At the time of large flow rate control, the flow rate of the fluid flowing through the throttle section is controlled by controlling the opening / closing control valve using the output of the pressure sensor, while at the time of low flow rate control, the opening / closing control valve is controlled using the output of the flow rate sensor. A mass flow controller comprising: a controller configured to control a flow rate of a fluid flowing through the flow rate sensor to thereby control a flow rate with a wide dynamic range. The mass flow controller according to claim 1, wherein the flow sensor is provided in a flow path on an upstream side of the on-off control valve. A first opening / closing control valve for controlling a flow of a fluid flowing in the flow path, a pressure sensor disposed downstream of the first opening / closing control valve,
A second on-off control valve disposed downstream of the pressure sensor;
A flow sensor for measuring the flow rate of the fluid flowing through the flow path,
At the time of large flow rate control, the second on-off control valve is fully opened and the output of the pressure sensor is used to open and close the first on-off control valve to control the flow rate of the fluid. A controller that controls the flow rate of the fluid flowing through the flow rate sensor by controlling the opening / closing of the second opening / closing control valve using the output, thereby enabling a flow rate control with a wide dynamic range. . The flow rate sensor is provided between a first opening / closing control valve and a second opening / closing control valve,
4. The mass flow according to claim 3, wherein the control unit performs control to stabilize the pressure of the fluid flowing into the flow sensor by controlling the opening and closing of the first opening / closing control valve using the output of the pressure sensor during the small flow control. 5. controller. The mass flow controller according to any one of claims 1 to 3, wherein the pressure sensor is provided in a flow path downstream of the flow sensor.

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