JPH07141032A - Flow rate controller - Google Patents

Abstract

PURPOSE:To precisely control a flow rate over a wide range, to more miniaturize the device and to reduce the price of added piping or wiring concerning the flow rate controller for controlling a gas flow rate. CONSTITUTION:The middle of one pipe provided with lead-in exhause ports on both sides is separated into plural branch pipes 5a, 5b and 5c, these branch pipes 5a, 5b and 5c are respectively provided with sensor parts 2a, 2b and 2c and all the branch pipes 5b and 5c excepting for one branch pipe 5a are provided with open/close valves 6a and 6b and flow rate control valves 7 for controlling the flow rate of gas to flow from the exhaust ports, and the flow rate is precisely controlled over the wide range from a small flow rate to a large flow rate. On the other hand, since one pipe is separated into the branch pipes 5a, 5b and 5c, the structure is integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate control device capable of adjusting the flow rate of a gas sent from a gas supply device at a constant flow rate in a wide range and delivering the gas.

[0002]

2. Description of the Related Art In recent years, semiconductor device manufacturing processes include many processes for forming a thin film on a semiconductor substrate and selectively etching the thin film. There is a CVD device or a dry etching device. A gas supply device for supplying gas to each processing chamber was attached to each of these facilities, and various gases were used. Also, depending on the conditions, even one kind of gas is 1
There was also a processing condition that required a large flow rate of 300 cc / min from a gas flow rate as small as -100 cc / min. Moreover, the accuracy of these gas flow rates had to be controlled within plus or minus 1%.

FIG. 3 is a schematic diagram showing the structure of a gas supply system for explaining an example of a conventional flow rate control device, and FIG. 4 is a schematic diagram showing the structure of the mass flow controller of FIG. Conventionally, this type of flow rate control device is, for example, as shown in FIG. 4, a mass flow controller 13a that is a plurality of flow rate control devices that introduce gas supplied from a gas cylinder 20 and independently control the flow rate and have different flow rate adjustment ranges. , 13b,
13c are connected in parallel, and the mass flow controller 13a,
This is a structure in which an opening / closing valve 14 is attached at the subsequent stage of each of 13b and 13c. Then, the valves 14 are arbitrarily opened and closed to mass flow controllers 13a, 13b, 13
The flow rate range is set depending on whether the system is one system, two systems, or three systems, and gas is supplied to the processing chamber 21 by controlling within the set flow range.

As shown in FIG. 4, a mass flow controller, which is an independent flow control device, has a main pipe 4 having a flow resistance inside, a bypass pipe 3 branched from this main pipe 4, and this bypass pipe. Sensor part 2 composed of two heaters 8 wound around the outer circumferences of the upstream side and the downstream side, a bridge circuit 18 connected to the bridge by the resistance of the heater 8 and the reference resistance, and the downstream side of the main pipe 4. And a control / power supply unit that inputs the output of the bridge circuit 18 and controls the opening of the flow control valve 7.

The mass flow controllers 13a to 13
In the operation of c, a part of the gas introduced from the main pipe 4 flows into the bypass pipe 3, the sensor unit 2 detects the flow rate, and the bridge circuit 18 controls the signal / power supply units 22a to 22c.
Is output to control the opening of the flow control valve 7 to set the total flow rate. The sensor unit 2 uses the temperature difference between the two heaters 8 caused by the flow of gas as a change in electric resistance and converts it into an electric signal using the bridge circuit 18.
Further, the flow rate ratio between the bypass pipe 3 and the main pipe 4 (flow rate of the main pipe / flow rate of the bypass pipe), that is, the diversion ratio is fixed so that the flow rate of the combined gas can be converted.

It is necessary to keep the diversion ratio large in order to keep the accuracy, but it is several cc / m due to the structure of the sensor section.
Since the gas can flow only in the range of 10 to 10 cc / min, there is a limit in suppressing the diversion ratio. Therefore,
The larger the maximum value of the total flow rate, the lower the accuracy on the low flow rate side as compared with the smaller value. Usually, accuracy is ± 1% of maximum flow rate
It is a degree. Here, if the flow rate range is 1 to 300 cc
/ Min, the maximum flow rate is 300cc / mi
n ± 1 to 300 when using a single flow controller
It becomes ± 3 cc / min, and the accuracy on the low flow rate side deteriorates.

Therefore, in order to obtain a flow rate with higher accuracy, a maximum flow rate value of 100 cc / min and a maximum flow rate value of 200
As shown in FIG. 3, control range of 1 to 1 is used by using three units of flow rate control device having cc / min and maximum flow rate value of 300 cc / min.
At 00 cc / min, the mass flow controller 13a having a maximum flow rate of 100 cc / min and the valve 14 are opened, and a single-system flow rate control device is used.
In cc / min, the mass flow controller 13a is set to the maximum flow rate value, and the system of the parallel mass flow controller 13b and the valve 14 is added to this and controlled. Further, in the control range 201 to 300 cc / min, the system of the mass flow controller 13a and the mass flow controller 13b is set to the maximum flow rate value, and the mass flow controller 13 is set.
The flow rate is controlled by the system of c and the opened valve 14.

As described above, in the conventional flow rate control device, if the mass flow controllers 13a, 13b and 13c are connected in parallel and the valve 14 is opened / closed to switch the flow rate from one system to three systems to control the flow rate, the flow rate in the low flow region is reduced. It was characterized by the ability to control a wide range of flow rates without sacrificing accuracy. By the way, this flow rate accuracy is 1 ± 1 ± 100 ± 1c
c / min, 101 ± 2 to 200 ± 2 cc / min, and 201 ± 3 to 300 ± 3 cc / min.

[0009]

However, in the above-described conventional flow control device, a plurality of flow control devices must be connected in parallel in order to accurately widen the flow control range. For this reason, a manifold is required for connecting the gas supply device and the mass flow controller, and the number of pipes and joints to these manifolds increases according to the number. For this reason, there is a problem in that the rate of occurrence of gas leak accidents at pipe joints and the like increases and the product yield decreases. In addition, the length of the wiring to the remote control and the power supply becomes long, and the resistance value increases correspondingly, making accurate control difficult. Further, there is a problem in that it becomes impossible to achieve miniaturization because a space is required around the device due to the lengthening of piping and wiring and the attachment of a manifold. Then, there is a drawback that materials and construction cost of piping and wiring increase with the increase in the number of mass flow controllers.

Therefore, it is an object of the present invention to provide a flow rate control device capable of precisely controlling the flow rate in a wide range, achieving a more compact size, and reducing the cost of associated piping and wiring.

[0011]

The features of the present invention include a gas introduction main pipe for introducing gas supplied from a gas supply device, a branch pipe branched from the main pipe into a plurality of pipes, and a plurality of the branch pipes. An on-off valve that leaves one of the pipes and is attached to the other branch pipes, a flow sensor that is attached to a bypass pipe branched from each of the branch pipes, and a gas that collects these branch pipes and discharges the gas. A main discharge pipe and a flow control valve attached to the main gas discharge pipe are provided, and the opening / closing valve is arbitrarily opened to change the number of the branch pipes through which the gas flows and the opening degree of the flow control valve. It is a flow rate control device that adjusts the flow rate of the gas led out from the gas discharge main pipe.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of the flow rate control device of the present invention. As shown in FIG. 1, this flow rate control device includes an introduction main pipe 1 for introducing a gas supplied from a gas cylinder, and branch pipes 5a, 5b, 5c branched from the introduction main pipe 1 into a plurality of pipes. Branch pipes 5a, 5
Branch pipes 5b and 5c except one of b and 5c
Open / close valves 6a and 6b attached to the pipes and bypass pipes 3 branched from the respective branch pipes 5a, 5b and 5c
Sensor parts 2a, 2b, 2 attached to a, 3b, 3c
c, a discharge main pipe 9 that collects the branch pipes 5a, 5b, and 5c to discharge the gas, and a flow control valve 7 attached to the discharge main pipe 9.

Here, the bypass pipes 3a, 3b and 3c having the sensor portions 2a, 2b and 2c are designed so that a gas of 10 cc / min flows, and the respective branch pipes 5a and 5c.
The diversion ratio with b and 5c is 9. Therefore, the branch pipe 5
The maximum flow rate of a, 5b, 5c becomes 100 cc / min. Further, since the diversion ratios are all equal, the sensor unit 2a,
The heaters 8a, 8b and 8c of 2b and 2c can be incorporated in one bridge circuit, and of course, the remote control / power supply unit for inputting the output of the bridge circuit and controlling the valve is also integrated into one control unit of the device. Can be incorporated into.

Next, the operation of this flow control device will be described. First, in the case of controlling in the control range of 1 to 100 cc / min, the opening / closing valves 6a and 6b are closed, and the flow is made to flow only through the branch pipe 5a. Then, the sensor section 2a detects the flow rate and controls the opening of the flow rate control valve 7 to set the flow rate.

Next, the control range 101 to 200 cc / mi
In the case of controlling by n, the opening / closing valve 6a is opened and the opening / closing valve 6b is kept closed, and the gas is allowed to flow through the branch pipes 5a, 5b. Since the heaters 8a and 8b of the sensors 2a and 2c are connected in series on the upstream side and the downstream side, respectively, the total flow rate of the gas flowing through the branch pipes 5a and 5b is detected, and the flow rate control valve is detected. With 7, the flow rate can be set within the above control range. Further, when controlling in the control range 201 to 300, the opening / closing valves 6a and 6b are opened, gas is caused to flow in all of the branch pipes 5a, 5b and 5c, and the flow rate control valve 7 is controlled to set the flow rate.

In this way, one introduction main pipe is branched so that a plurality of gas supply systems are reassembled to form one discharge pipe, so that it is easy to integrate, and accordingly, the pipes conventionally attached are eliminated. As a result, no joints or manifolds are needed.

FIG. 2 is a schematic diagram showing an example in which the flow rate control device of FIG. 1 is applied to a processing device. For example, as shown in FIG. 2, when applied to a processing apparatus such as a dry etching apparatus, the discharge pipe of the flow rate control apparatus 10 can be directly connected to the processing chamber 21, and a joint is not necessary. Also, the input side can be directly connected to the gas cylinder 20, and the need for a manifold, a pipe support, etc. as in the conventional case is eliminated.
Furthermore, the control / power supply unit 22 for remote control can also be integrated into one rack and stored in the control unit of the apparatus. By disposing the control unit adjacent to the processing chamber 21, the wiring can be shortened and the increase in the resistance component is eliminated as in the conventional case, and accurate control can be performed.

[0019]

As described above, according to the present invention, one pipe having an inlet / outlet on both sides is divided into a plurality of branch pipes, and a flow sensor is provided in each of these branch pipes. All branch pipes except for are equipped with open / close valves, and flow control valves that control the flow rate of gas flowing from the exhaust port, and open / close valves arbitrarily in sequence to provide a wide range of flow rates from small to large. The effect is that the can be set precisely. In addition, since it is possible to form a branch pipe by branching from a single pipe having an inlet / outlet on both sides, it is easy to make an integrated structure and downsizing is possible. Since it can be connected to the supply device, there is an effect that the conventionally required long piping and wiring, etc. are eliminated, and the cost of incidental parts can be reduced and the construction cost associated therewith can be saved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a flow rate control device of the present invention.

FIG. 2 is a schematic diagram showing an example in which the flow rate control device of FIG. 1 is applied to a processing device.

FIG. 3 is a schematic diagram showing a configuration of a gas supply system for explaining an example of a conventional flow rate control device.

FIG. 4 is a schematic diagram showing the structure of the mass flow controller of FIG.

[Explanation of Codes] 1 main piping 2, 2a, 2b, 2c sensor section 3, 3a, 3b, 3c bypass piping 4 main piping 5a, 5b, 5c branch piping 6, 14 open / close valve 7 flow control valve 8, 8a, 8b, 8c Heater 9 Discharge main piping 10, 13 Flow rate control device 18 Bridge circuit 20 Gas cylinder 21 Processing chamber 22, 22a, 22b, 22c Control / power supply unit

Claims (1)

[Claims] 1. A gas introduction main pipe for introducing a gas supplied from a gas supply device, a branch pipe branched from the main pipe into a plurality of pipes, and one of the plurality of branch pipes is left and the other pipes are left. An on-off valve attached to the branch pipe, a flow rate sensor attached to each bypass pipe branched from the branch pipe, a gas discharge main pipe that collects the branch pipes and discharges the gas, and a gas discharge main pipe A flow control valve attached to the gas discharge main pipe by changing the number of the branch pipes through which the gas flows and changing the opening of the flow control valve. A flow control device characterized by adjusting the flow rate of gas.