JP7051211B2 - Fluid control devices, control programs and fluid control systems - Google Patents

Description

The present invention relates to fluid control devices, control programs and fluid control systems.

Conventionally, in the semiconductor manufacturing process, a fluid control device is installed in the flow path for supplying the fluid to the film forming chamber (chamber), and the fluid control device accurately controls the flow rate of the fluid flowing through the flow path. The system is in use. The fluid control device is a so-called mass flow controller, includes a fluid sensor that measures the fluid flowing in the flow path, and a fluid control valve that controls the fluid, and the measured value of the fluid sensor is a predetermined target value. The fluid control valve is feedback-controlled so as to approach.

By the way, the fluid control valve included in the fluid control device has a low shut-off property due to its structural problem, and in order to improve this point, as shown in Patent Document 1, on the upstream side or the downstream side of the fluid control device. An on-off valve is installed on either one or both of them, and the on-off valve is opened and closed to supplement the shut-off property of the fluid control valve.

However, in such a fluid control system, when the operation to fully close the on-off valve is performed while continuing the feedback control of the fluid control device, and then the on-off valve is returned to the open state, the fluid is fluidized. There was a problem that the control device caused a control failure.

More specifically, if the on-off valve is fully closed while the fluid control device continues feedback control, the fluid naturally stops flowing in the flow path, and the fluid control device flows by feedback control accordingly. The valve opening of the fluid control valve is controlled to be larger in order to maintain the flow rate of the fluid flowing through the path. When this control continues, the fluid control valve is in a state of maintaining a fully open state or a state close to it (hereinafter, both states are collectively referred to as a fully open state). If the on-off valve is returned to the open state in this state, the fluid will flow into the fully open fluid control valve at once, causing overshoot and hunting, resulting in poor control.

In particular, it is used in the fluid control system in the ALD (Atomic Layer Deposition) film formation technology (the film formation technology that supplies the fluid as a material to the film formation chamber in a pulse shape), which is becoming mainstream in recent years. As a fluid control device, a device in which the gain value of feedback control is set to a larger value than the conventional one is used in order to improve the responsiveness, and the above-mentioned problem appears more prominently and is improved. Is required.

JP-A-2010-08475 Japanese Patent Application Laid-Open No. 10-55201

Therefore, the main object of the present invention is to provide a fluid control device in which control failure is unlikely to occur even when the operation is performed in the fluid control system.

That is, in the fluid control device according to the present invention, the fluid sensor that measures the fluid flowing in the flow path, the fluid control valve that controls the fluid, and the measured value measured by the fluid sensor are set to predetermined target values. A fluid control unit that feedback-controls the fluid control valve so as to approach the fluid control valve is provided, and the fluid control unit is equal to or less than the underflow threshold value at which the measured value measured by the fluid sensor is smaller than the target value. Moreover, the present invention is characterized by including a determination unit for determining whether or not an abnormal state has been reached in which the valve opening degree of the fluid control valve is continuously equal to or greater than the limit value.

In such a case, the fluid control device can immediately detect that an abnormal state has occurred in which the on-off valve is maintained in a closed state while continuing feedback control, and necessary measures can be taken. become.

Further, when the determination unit determines that the abnormal state has occurred, the gain value used for the feedback control is changed to a value smaller than the gain value used for the feedback control when the abnormal state is not obtained. It may be further provided with a change part.

In such a case, the gain value used for feedback control by the gain changing unit is small when an abnormal state occurs in which the on-off valve is maintained in the closed state while the feedback control is continued by the fluid control device. Change to value. As a result, when the on-off valve is opened again from the abnormal state, even if the fluid flows into the fluid control valve in the state where the valve opening is equal to or more than the limit value at once, the feedback control has a relatively small gain. Since it is executed using the value, large overshoot and hunting are less likely to occur, and as a result, control failure is less likely to occur in the fluid control device.

When the valve opening of the fluid control valve is equal to or greater than the limit value, the valve opening of the fluid control valve is at the limit value that is mechanically determined, in other words, the so-called fully open state. Not only the state but also the state in which the valve opening degree of the fluid control valve is equal to or higher than the limit value set by the user is included. Further, the state in which the valve opening degree of the fluid control valve is fully opened includes not only the state in which the valve opening degree is 100% but also the state in which the valve opening degree is close to 100%. That is, when the valve opening degree of the fluid control valve is fully opened, the valve opening degree is smaller than 100% and is equal to or higher than a threshold value close to 100% (for example, the valve opening degree is high). The state of 98% to 100%) is also included. In this case, it can be said that the threshold value close to 100% (for example, 98%) is the limit value.

Further, the determination unit has a measured value measured by the fluid sensor that is less than or equal to the underflow threshold value that is smaller than the target value, and the valve opening degree of the fluid control valve is equal to or more than the limit value. It may be configured to determine that an abnormal state has occurred when the state of being in the state is continued for a predetermined time or longer.

In such a case, when the flow rate of the fluid flowing in the flow path is feedback-controlled, the valve opening of the fluid control valve is temporarily the limit value for some reason even in a state other than the abnormal state. In such a case, the gain value used for the feedback control is maintained at the gain value used for the feedback control when the abnormal state is not obtained.

Further, the determination unit is configured to determine whether or not the valve opening degree of the fluid control valve is equal to or greater than the limit value based on the voltage value or the current value applied to the fluid control valve. It may be the one that has.

Further, the gain changing unit changes the gain value to a value smaller than the stable gain value used for feedback control in a stable state in which the deviation between the measured value measured by the fluid sensor and the target value falls within a predetermined range. It may be configured, and the gain changing unit changes the gain value to a value smaller than the transient gain value used for feedback control in the transient state after changing the target value. It may be the one that has become.

In such a case, in a fluid control device such as ALD where a response speed is required, a relatively high value is set as a stable gain value or a transient gain value, but when an abnormal state occurs. By changing the gain value to a value smaller than these gain values, it is possible to suppress the occurrence of control failure when the abnormal state is subsequently resolved.

Further, the fluid control system according to the present invention includes one of the above-mentioned fluid control devices and an on-off valve installed on either one or both of the upstream side and the downstream side of the fluid control device.

Further, in the control program used in the fluid control device according to the present invention, a fluid sensor for measuring the fluid flowing in the flow path, a fluid control valve for controlling the fluid, and a measured value measured by the fluid sensor are predetermined. It is a control program used for a fluid control device including a fluid control unit that feedback-controls the fluid control valve so as to approach the target value, and the measured value measured by the fluid sensor is larger than the target value. It is determined whether or not an abnormal state has been reached in which the state of being equal to or less than the underflow threshold value, which is a small value, and the valve opening degree of the fluid control valve is equal to or more than the limit value is continued, and the determination unit determines the abnormality. It is characterized in that the gain value used for the feedback control is changed to a value smaller than the gain value used for the feedback control when it is determined that the state has been reached.

According to the fluid measuring device configured as described above, even when the on-off valve is opened and closed while the fluid control device continues the feedback control in the fluid control system, control failure is unlikely to occur.

It is a schematic diagram which shows the whole structure of the fluid control system which concerns on Embodiment 1. FIG. It is a schematic diagram which shows the structure of the fluid control apparatus of the fluid control system which concerns on Embodiment 1. FIG. It is a flowchart which shows the operation of the fluid control apparatus which concerns on Embodiment 1. FIG. It is a graph which shows the relationship between the measured value of the flow rate sensor which concerns on Embodiment 1 and a target value.

Hereinafter, the fluid control device according to the present invention and the fluid control system using the fluid control device will be described with reference to the drawings.

The fluid control system according to the present invention is used to supply a fluid containing a specific component to be a material for film formation to a supply destination such as a film formation chamber (chamber) used in a semiconductor manufacturing process. Is. The fluid measurement system according to the present invention can be used not only in the semiconductor control process but also in other processes.

<Embodiment 1>

As shown in FIG. 1, the fluid control system 100 according to the present embodiment includes a fluid control device 10 installed in a flow path L for supplying a fluid from the fluid supply device T to the film forming chamber C, and a fluid. It includes an on-off valve V installed on the upstream side and the downstream side of the control device 10. The fluid supply device T is connected to the upstream side of the flow path L, and the film forming chamber C is connected to the downstream side of the flow path L.

The fluid control device 10 is a so-called mass flow controller, and in the present embodiment, a thermal type is used. Specifically, as shown in FIG. 2, the fluid control device 10 is a block body 20 provided with a flow path L and a flow rate sensor installed in the block body 20 to measure the flow rate of the fluid flowing through the flow path L. The flow path L is adjusted by adjusting the valve opening degree of the fluid control valve 40 installed on the downstream side of the flow rate sensor 30 of the block body 20 and the fluid control valve 40 based on the measured values measured by the flow rate sensor 30. A fluid control unit 50 that controls the flow rate of the fluid flowing through the water is provided.

The flow rate sensor 30 measures the flow rate of the fluid flowing through the flow path L, and is a so-called thermal flow rate sensor. Specifically, the flow sensor 30 includes a measuring tube 31 that bypasses the flow path L, and a pair of heat generating resistors 32 wound around the upstream side and the downstream side of the measuring tube 31. The flow rate sensor 30 further includes a flow rate calculation unit 33 that calculates the flow rate of the fluid flowing through the measuring tube 32 based on the temperature difference between the pair of heat generating resistors 32 caused by the flow of the fluid through the measuring tube 31. The flow rate calculation unit 33 calculates the flow rate flowing through the flow path L based on the flow rate dividing ratio between the flow path L and the measuring tube 31. A laminar flow element 34 is provided between the branch point and the confluence point with the measuring tube 31 in the flow path L.

The fluid control valve 40 plans the valve seat 41, the valve body 42 that moves in the contacting / separating direction with respect to the valve seat surface 41s of the valve seat 41, the plunger 43 connected to the valve body 42, and the valve body 42. It includes an actuator 44 that is moved via 43, and a case 45 that houses each of these members. Then, the fluid control valve 40 is in a fully closed state by bringing the contact surface 42s of the valve body 42 into contact with the valve seat surface 41s of the valve seat 41, and the fluid control valve 40 is in a fully closed state, and is between the valve seat surface 41s and the contact surface 42s. The distance is the valve opening. In this embodiment, the piezo element is used as the actuator 44.

The flow rate control unit 50 has a so-called computer equipped with a CPU, a memory, an A / D / D / A converter, and the like, and the program stored in the memory is executed, and various devices cooperate with each other to execute the above. Each function is realized. An input unit 60 and an output unit (not shown) are connected to the fluid control unit 50.

More specifically, the flow control unit 50 has a target value storage unit 51 that stores a target value previously input from the input unit 60, and a valve opening degree of the fluid control valve 40 based on the measured value measured by the flow sensor 30. A gain change that changes the gain value used for feedback control based on the judgments made by the feedback control unit 52 that controls feedback, the determination unit 53 that determines whether or not the fluid control device 10 is in an abnormal state, and the determination unit 53. It is provided with a unit 54 and.

The target value storage unit 51 stores a target value that is a target flow rate of the fluid controlled by the fluid control device 10. The target value storage unit 51 is connected to the input unit 60 so that the user can input and set the target value from the input unit 60 in advance.

The feedback control unit 52 PID controls the fluid control valve 40 so that the measured value of the flow rate sensor 30 approaches the target value. There are the following three gain values used for feedback control, and they are set according to each state.
A stable gain value set when the measured value of the flow rate sensor 30 becomes a stable state within the range between the excessive flow rate threshold value indicating the upper limit value of the allowable deviation from the target value and the underflow rate threshold value indicating the lower limit value. .. (Note that the stable state can be said to be a state in which the deviation between the measured value of the flow rate sensor 30 and the target value falls within the range of the difference between the excessive flow rate threshold value and the underflow rate threshold value.)
-A transient gain value set when the measured value of the flow rate sensor 30 is in a transition state. (Note that the transition state is a transition state after the target value is changed.)
-It is set when the measured value of the flow rate sensor 30 is equal to or less than the underflow threshold value and the valve opening of the fluid control valve is equal to or more than the limit value in an abnormal state in which the state continues for a predetermined time or longer. Abnormal gain value.

The determination unit 53 includes a flow rate determination unit 53a for determining whether or not the measured value of the flow rate sensor 30 is equal to or less than the underflow rate threshold, and whether or not the valve opening degree of the fluid control valve 40 is equal to or greater than the limit value. The measured value of the flow rate sensor 30 is equal to or less than the underflow rate threshold value based on the determination results of the valve opening degree determination unit 53b, the flow rate determination unit 53a, and the valve opening degree determination unit 53b. It is provided with a time measuring unit 53c for measuring the duration during which the state in which the valve opening degree of the valve is maintained to be equal to or higher than the limit value is maintained. Then, the determination unit 53 sequentially executes the determination by the flow rate determination unit 53a and the determination by the valve opening degree determination unit 53b in this order, and also refers to the duration measured by the time measurement unit 53c to control the fluid. It is configured to determine whether or not the device 10 is in an abnormal state. The abnormal state is a state in which no fluid is flowing in the flow path L and the valve opening degree of the fluid control valve 40 is equal to or more than the limit value for a predetermined time or longer. The fluid control device 10 is in an abnormal state because, for example, the feedback control is continued in the feedback control unit even though the on-off valve V is closed.

Specifically, the valve opening degree determination unit 53b determines whether or not the valve opening degree of the fluid control valve 40 is equal to or greater than the limit value based on the voltage value applied to the actuator 44 that moves the valve body 42. Is to be determined. In addition, when the valve opening is equal to or more than the limit value, the valve opening of the fluid control valve 40 is equal to or more than the limit value determined by the mechanism, in other words, only in the so-called fully open state. However, it also includes a state in which the valve opening of the fluid control valve is equal to or higher than the limit value set by the user.

The gain changing unit 54 changes the gain value to a value smaller than the gain value used for the feedback control when the determination unit 53 determines that the abnormal state is not present. Specifically, the abnormal gain value is set to a value smaller than at least a stable gain value or an under-transient gain value. Then, when the determination unit 53 determines that the abnormal state is present, the gain changing unit 54 changes the stable gain value or the undertransient gain value to the abnormal gain value. Specifically, the gain changing unit 54 may change the P gain in the PID control, and the abnormal gain value may be set to be half the stable gain value or the transient gain value.

The on-off valve V completely shuts off the flow of the fluid flowing through the flow path L, and assists the fluid control valve 40 having a low shut-off property. Specifically, a pneumatic valve or the like can be used.

Next, the determination operation of the fluid control device in the fluid control system according to the present embodiment will be described with reference to FIG. In the determination operation, the unit determination operation is repeatedly executed at predetermined intervals, and FIG. 3 is a flowchart showing a series of flow of the unit determination operation. Further, FIG. 4 is a graph for explaining each value used for the determination operation in the flow rate determination unit 53a.

Prior to explaining the determination operation of the determination unit 53, each value used for the determination operation in the flow rate determination unit 53a will be described with reference to FIG. FIG. 4 is a graph in which the vertical axis is the measured value of the flow rate sensor 30 and the horizontal axis is the target value. Then, in FIG. 4, the solid line X indicates an ideal stable state in which the measured value and the target value match, and the broken line Y indicates the lesser side of the measured value that can be tolerated as the stable state from the target value. Shows the range of deviation. Therefore, it can be said that the stable state is a state in which the measured value is at least between the broken line X and the broken line Y. When paying attention to a predetermined target value, the difference between the broken line X and the broken line Y at the predetermined target value becomes the underflow rate allowable value. That is, the underflow permissible value is a value indicating the range of deviation of the measured value that can be tolerated as a stable state from the target value to the underside side at a predetermined target value.

By the way, the flow rate determination unit 53a determines whether or not the measured value of the flow rate sensor 30 is equal to or less than the underflow rate threshold value which is a value obtained by subtracting the underflow allowance value from the target value. However, as can be seen from FIG. 4, when the target value is equal to or less than the value equal to the underflow allowance value (indicated by α in FIG. 4), the underflow threshold becomes a negative value and cannot be correctly determined. Therefore, in order to avoid such a situation, the underflow rate lower limit value (indicated by β in FIG. 4) is set, and the value obtained by subtracting the underflow rate permissible value from the target value becomes equal to or less than the underflow rate lower limit value. Is set to the underflow rate lower limit value as the underflow rate threshold value. Based on the above, the determination operation of the determination unit 53 will be specifically described.

When the determination operation is started by the determination unit 53, the measurement by the time measurement unit 53c is started at the same time. Then, the determination unit 53 executes the determination operation by the flow rate determination unit 53a and then executes the determination operation by the valve opening degree determination unit 53b to end the unit determination operation.

First, the flow rate determination unit 53a determines whether or not the measured value of the flow rate sensor 40 is equal to or less than the underflow rate threshold value. Specifically, the flow rate determination unit 53a compares the value obtained by subtracting the underflow allowance value from the target value with the underflow lower limit value (step 1). Then, when the flow rate determination unit 53a determines in step 1 that the value is larger than the underflow lower limit value, the flow rate determination unit 53a recognizes the value as the underflow threshold value (step 2), and subsequently measures the flow rate sensor 40. The value is compared with the underflow threshold (step 3). When the flow rate determination unit 53a determines in step 3 that the measured value is equal to or less than the underflow rate threshold value, the flow rate determination unit 53a shifts to the determination by the valve opening degree determination unit 53b, and determines that the measured value is larger than the underflow rate threshold value. The unit determination operation is terminated by resetting the duration measured by the time measuring unit 53c (step 4).

On the other hand, when the flow rate determination unit 53a determines in step 1 that the value is smaller than the underflow lower limit value, the flow rate determination unit 53a recognizes the underflow rate lower limit value as the underflow rate threshold value (step 5), and subsequently, the flow rate sensor. The measured value of 40 is compared with the underflow threshold (step 3). When the flow rate determination unit 53a determines in step 3 that the measured value is equal to or less than the underflow rate threshold value, the flow rate determination unit 53a shifts to the determination by the valve opening degree determination unit 53b, and determines that the measured value is larger than the underflow rate threshold value. The unit determination operation is terminated by resetting the duration measured by the time measuring unit 53c (step 4).

Next, when the determination is made by the valve opening degree determination unit 53b in step 3, the valve opening degree determination unit 53b has a calculated valve opening degree of the limit value or more calculated based on the voltage value applied to the fluid control valve 40. It is determined whether or not it is (step 6). Then, when the valve opening degree determination unit 53b determines in step 6 that the calculated valve opening degree is equal to or greater than the limit value, the valve opening degree determination unit 53b starts a determination operation with respect to the continuation time measured by the time measurement unit 53c. The elapsed time since then is added (step 7). On the other hand, when the valve opening degree determination unit 53b determines in step 6 that the calculated valve opening degree does not exceed the limit value, the valve opening degree determination unit 53b resets the duration measured by the time measurement unit 53c and performs a unit determination operation. Is finished (step 4).

Next, the valve opening degree determination unit 53b determines whether or not the duration after adding the elapsed time in step 7 is equal to or longer than a predetermined time (step 8), and the valve opening degree determination unit 53b is a step. When it is determined in 8 that the duration is longer than the predetermined time, it is determined that an abnormal state has occurred and the unit determination operation is terminated (step 9). On the other hand, when the valve opening degree determination unit 53b determines in step 8 that the duration is not longer than the predetermined time, the valve opening degree determination unit 53b ends the unit determination operation in a state where the duration is maintained without being reset (step 10). ).

That is, in the determination unit 53, the state in which the measured value measured by the flow rate sensor 30 is equal to or less than the underflow threshold value and the state in which the valve opening degree of the fluid control valve 40 is equal to or more than the limit value are simultaneously performed. By determining whether or not the situation that occurs has elapsed for a predetermined time or more, it is determined whether or not the fluid control device 10 has become an abnormal state.

Then, the gain changing unit 54 changes the gain value used for the feedback control to the abnormal gain value when the determination unit 50 determines that the abnormal state is present. As a result, even if the on-off valve V is opened after the fluid control device 10 is in an abnormal state and the fluid flows into the fluid control valve 40 in a state where the valve opening is equal to or higher than the limit value, feedback control is performed. Since the gain value used for is set to a relatively small value, the degree of overshoot and hunting can be reduced, and control failure is less likely to occur.

<Other Embodiments> In the valve opening degree determination unit 53b in the above embodiment, a step for determining whether the fluid control valve 40 is a normally open type or a normally closed type is added, and after adding this step, step 7 is performed. It may be configured to run. By adding the above step, the correct valve opening degree can be calculated based on the voltage value regardless of which type of fluid control valve 40 is used.

In the valve opening degree determination unit 53b in the embodiment, the valve opening degree of the fluid control valve 40 is calculated based on the voltage value applied to the actuator 44, but is calculated based on the current value applied to the actuator 44. You may. Further, the fluid control valve 40 may be provided with a position sensor for detecting the position of the valve body 42 with respect to the valve seat 41, and the valve opening degree may be calculated based on the output value of the position sensor. In this case, the fluid control valve 40 includes a position sensor for measuring the position of the valve body 42 with respect to the valve seat 41, and whether or not the determination unit 53 has entered the abnormal state based on the output value of the position sensor. It suffices to provide the valve opening degree determination unit 53b for determining whether or not. Further, it may be determined whether or not the valve opening degree of the fluid control valve 40 is equal to or greater than the limit value based on the output value of the position sensor.

Further, in the determination unit 53 in the embodiment, after the flow rate determination unit 53a executes the determination, the valve opening degree determination unit 53b executes the determination, but the valve opening degree determination unit 53b executes the determination first. Then, the determination by the flow rate determination unit 53a may be executed thereafter.

In the above embodiment, a thermal type is used as the fluid control device, but a pressure type or a position sensor type may be used.

In addition, the present invention is not limited to each of the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

100 Fluid control system L Flow path V On-off valve 10 Fluid control device 30 Fluid sensor 40 Fluid control valve 50 Fluid control unit 51 Target value storage unit 52 Feedback control unit 53 Judgment unit 53a Flow rate determination unit 53b Valve opening degree determination unit 53c Time measurement Part 54 Gain change part

Claims (7)

A fluid sensor that measures the fluid flowing through the flow path,
A fluid control valve that controls the fluid and
It is provided with a fluid control unit that feedback-controls the fluid control valve so that the measured value measured by the fluid sensor approaches a predetermined target value.
The fluid control unit
An abnormal state in which the measured value measured by the fluid sensor is equal to or less than the underflow threshold value, which is smaller than the target value, and the valve opening degree of the fluid control valve is equal to or more than the limit value. Equipped with a judgment unit that determines whether or not it has become
A gain changing unit that changes the gain value used for the feedback control to a value smaller than the gain value used for the feedback control when the determination unit determines that the abnormal state has occurred. A fluid control device characterized by further comprising. The determination unit is in a state where the measured value measured by the fluid sensor is equal to or less than the underflow threshold value which is smaller than the target value, and the valve opening degree of the fluid control valve is equal to or more than the limit value. The fluid control device according to claim 1 , wherein it is determined that an abnormal state has occurred when the fluid control is continued for a predetermined time or longer. The determination unit is configured to determine whether or not the valve opening degree of the fluid control valve is equal to or greater than the limit value based on the voltage value or current value applied to the fluid control valve. The fluid control device according to any one of claims 1 or 2 . The gain changing unit changes the gain value to a value smaller than the stable gain value used for feedback control in a stable state in which the deviation between the measured value measured by the fluid sensor and the target value falls within a predetermined range. The fluid control device according to any one of claims 1 to 3, which is configured. According to any one of claims 1 to 3, the gain changing unit is configured to change the gain value to a value smaller than the transient gain value used for feedback control in the transient state after changing the target value. The described fluid control device. The fluid control device according to any one of claims 1 to 5 .
A fluid control system comprising an on-off valve installed on either one or both of the upstream side and the downstream side of the fluid control device. The fluid sensor that measures the fluid flowing in the flow path, the fluid control valve that controls the fluid, and the fluid control valve are feedback-controlled so that the measured value measured by the fluid sensor approaches a predetermined target value. A control program used in a fluid control device including a fluid control unit.
An abnormal state in which the measured value measured by the fluid sensor is equal to or less than the underflow threshold value, which is smaller than the target value, and the valve opening degree of the fluid control valve is equal to or more than the limit value. A judgment unit that determines whether or not it has become
A gain changing unit that changes the gain value used for the feedback control to a value smaller than the gain value used for the feedback control when the determination unit determines that the abnormal state has occurred. A control program used in a fluid control device, which is characterized by having the functions of

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