JP5118216B2 - Vacuum pressure control system and vacuum pressure control program - Google Patents

Description

The present invention is used in a vacuum pressure control system and a vacuum pressure control system that control a vacuum pressure in a reaction chamber to a target pressure by a vacuum proportional on-off valve disposed on a pipe connecting the reaction chamber and a vacuum pump. It relates to a vacuum pressure control program.

For example, in a CVD apparatus of a semiconductor manufacturing apparatus, a material gas composed of elements constituting a thin film material is supplied onto a wafer while keeping a reaction chamber in a reduced pressure state, that is, in a vacuum state. For example, in the CVD apparatus shown in FIG. 31, the material gas is supplied from the inlet 11 of the reaction chamber 10 to the wafer in the reaction chamber 10 which is a vacuum vessel, and the vacuum pump 13 is supplied from the outlet 12 of the reaction chamber 10. By evacuating, the inside of the reaction chamber 10 is kept in a vacuum state.

Since the vacuum pressure in the reaction chamber 10 affects the product quality, it is necessary to keep the target vacuum pressure value constant. The target vacuum pressure value that is kept constant varies depending on various conditions. Therefore, the vacuum pressure in the reaction chamber 10 needs to be controllable from a low vacuum close to atmospheric pressure to a high vacuum. In the conventional vacuum pressure control system, a vacuum proportional on-off valve 16 is arranged on a pipe connecting the reaction chamber 10 and the vacuum pump 13, and the vacuum pressure in the reaction chamber 10 measured by the vacuum pressure sensors 14 and 15 is externally measured. The reaction chamber 10 is operated by changing the conductance of the exhaust system from the reaction chamber 10 to the vacuum pump 13 by operating the valve opening degree of the vacuum proportional on-off valve 16 according to the difference from the given target vacuum pressure value. Feedback control of the vacuum pressure inside. The vacuum proportional on-off valve controls the valve opening degree by the cylinder pressure, and an O-ring is mounted on the surface where the valve body comes into contact with the valve seat. Such a vacuum proportional on-off valve 16 can be controlled to a minute flow rate by changing the collapse amount of the O-ring to cause leakage.

When the vacuum pressure in the reaction chamber 10 is controlled when the vacuum pressure in the reaction chamber 10 is changed, particles are rolled up in the reaction chamber 10 to deteriorate the product yield. On the other hand, if the vacuum pressure in the reaction chamber 10 is changed slowly in order to prevent the particles from rolling up, the batch processing time in the reaction chamber 10 is prolonged. Therefore, for example, in Patent Document 1, in the preparatory stage before executing the vacuum pressure control, after applying a preload to the vacuum pressure control valve 16, the valve of the vacuum proportional on-off valve 16 is executed in the stage of executing the vacuum pressure control. A technique has been proposed in which the opening is manipulated so that the vacuum pressure in the reaction chamber 10 is uniformly changed at a target vacuum pressure change rate given from the outside or set in advance in a controller.

FIG. 32 is a flowchart of a vacuum pressure control program in the vacuum pressure control system described in Patent Document 1.
As shown in FIG. 32, in the preparation stage of vacuum pressure control, first, the current vacuum pressure in the reaction chamber 10 is measured by the vacuum pressure sensors 14 and 15 (step 101 (hereinafter abbreviated as “S101”)). . Then, a command signal is output from the controller so that the valve opening degree of the vacuum proportional on-off valve 16 changes in a ramp function from the blocked state (S102). In this state, the vacuum pressure in the reaction chamber 10 is measured with 10 sec as the upper limit, and it is repeatedly confirmed whether or not there has been a slight pressure drop (for example, a pressure drop of 266 Pa or more) (S103 to 105).

When 10 seconds have elapsed since the start of the vacuum pressure control (S103: YES), or when the vacuum pressure in the reaction chamber 10 drops (for example, a pressure drop of 266 Pa or more) (S105: YES), the current in the reaction chamber 10 A value obtained by subtracting 266 Pa from the vacuum pressure is set as a feedback control target value, and feedback control (constant value control) is performed (S106, S107). When 10 seconds have elapsed since the start of the constant value control (S108: YES), the preparation stage of the vacuum pressure control is terminated and the vacuum pressure control is started.

In the execution stage of the vacuum pressure control, the desired vacuum pressure and the current vacuum pressure in the reaction chamber 10 are acquired, and it is determined whether or not the current vacuum pressure has reached the desired vacuum pressure (S109 to S111). Until the desired vacuum pressure is reached (S111: NO), the desired vacuum pressure change rate is obtained, the vacuum pressure in the reaction chamber 10 is obtained, and the target value of the feedback control is changed based on them, Generate internal commands sequentially. Then, sequentially generated internal commands are set as feedback control target values, and feedback control is performed as follow-up control (S112 to S115, S109, S110). In this way, when the current vacuum pressure in the reaction chamber 10 reaches a desired vacuum pressure by performing the feedback control while sequentially changing the feedback control target value (S111: YES), the feedback control target at that time point The value is set to a desired vacuum pressure, and feedback control is performed (S116, S115).

According to such a vacuum pressure control system, for example, the vacuum proportional on-off valve 16 is preloaded due to factors such as a mechanical zero point shift of the vacuum proportional on-off valve 16 and a pressure difference between the reaction chamber 10 and the vacuum pump 13. Even if the degree is changed, the dead zone characteristic of the vacuum proportional on-off valve 16 is surely eliminated by executing the feedback control after the preload in the preparation stage of the vacuum pressure control. Thereby, the vacuum proportional on-off valve 16 does not generate a response delay when the vacuum pressure in the reaction chamber 10 is uniformly changed at a target vacuum pressure change rate given from the outside or set in the controller in advance. It is possible to prevent the particles from being rolled up by slowly performing the process of discharging the gas from the chamber 10. Further, since the vacuum pressure in the reaction chamber 10 is uniformly changed at the target vacuum pressure change rate, the vacuum pressure change rate in the reaction chamber 10 does not slow inversely, and the vacuum pressure in the reaction chamber 10 is reduced. The time required to reach the target vacuum pressure value can be shortened, and the batch processing time in the reaction chamber 10 can be shortened.

JP 2000-163137 A

However, in the conventional vacuum pressure control system, the cylinder of the vacuum pressure control valve 16 is preloaded in order to eliminate the dead zone of the vacuum pressure on / off valve 16. At this time, since the position where the sealing force of the vacuum pressure control valve 16 is lost (leak start position) is unknown, the amount that can be preloaded is unknown. Therefore, the conventional vacuum pressure control system performs constant value control after preloading (S102 to S108). The preload and the constant value control each take 10 seconds, and a dead time of 20 seconds at maximum occurs. Therefore, the conventional vacuum pressure control system has a problem of poor pressure control response.

Moreover, in the conventional vacuum pressure control system, when a pressure drop of 266 Pa occurs, a value obtained by subtracting 266 Pa from the vacuum pressure in the reaction chamber 10 at that time is set as a feedback control target value (S106), and preloading is performed. . Therefore, the conventional vacuum pressure control system may not be able to preload the cylinder of the vacuum proportional on-off valve 16 so that the lower limit value of the feedback control is set to the leak start position of the O-ring.

The vacuum pressure control system in which the lower limit value of the feedback control deviates from the leak start position of the O-ring. When overshoot, hunting, or undershoot occurs, the valve body shown in FIG. It sometimes moved beyond the valve seat. When fluid is then flowed, useless time occurs from when the valve body starts to move until fluid begins to leak from the O-ring. Therefore, in the conventional vacuum pressure control system, the vacuum proportional on-off valve 16 performs the valve opening / closing operation by passing through the league position of the O-ring, and the pressure control responsiveness may be lacking.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vacuum pressure control system and a vacuum pressure control program capable of improving pressure control responsiveness.

The vacuum pressure control system and the vacuum pressure control program according to the present invention have the following configurations.
(1) According to one aspect of the present invention, a valve body, a valve seat on which the valve body abuts or separates, and an elastic seal member such as an O-ring mounted on a surface of the valve body that abuts on the valve seat And a cylinder for applying a driving force to the valve body, and adjusting a minute flow rate by changing a crushing amount of the elastic seal member, which is disposed between the reaction chamber and the vacuum pump. A vacuum having a vacuum proportional on-off valve and control means for adjusting the valve opening degree of the vacuum proportional on-off valve based on the vacuum pressure in the reaction chamber and feedback-controlling the vacuum pressure in the reaction chamber to a vacuum target pressure value The pressure control system includes pressure measuring means for measuring an internal pressure of the cylinder, and the control means calculates a preload pressure value from a vacuum pressure in the reaction chamber or a vacuum pressure target value, and calculates the preload pressure value as the pressure control system. Lower limit of feedback control To.

(2) According to another aspect of the present invention, a valve body, a valve seat on which the valve body abuts or separates, an elastic seal member mounted on a surface of the valve body that abuts on the valve seat, A vacuum proportional on-off valve having a cylinder for applying a driving force to the valve body and adjusting a minute flow rate by changing a crushing amount of the elastic seal member between the reaction chamber and the vacuum pump, In the vacuum pressure control system that adjusts the valve opening degree of the vacuum proportional on-off valve based on the vacuum pressure of the vacuum chamber and feedback-controls the vacuum pressure in the reaction chamber to the vacuum target pressure value, pressure measurement for measuring the internal pressure of the cylinder Having means,
A vacuum pressure in the reaction chamber or a preload pressure value calculated from a vacuum pressure target value is input, and the preload pressure value is set as a lower limit value of the feedback control.

(3) According to another aspect of the present invention, a valve body, a valve seat on which the valve body abuts or separates, an elastic seal member mounted on a surface of the valve body that abuts on the valve seat, A cylinder that applies a driving force to the valve body, and adjusts a minute flow rate by changing a crushing amount of the elastic seal member, and is a vacuum proportional opening and closing disposed between a reaction chamber and a vacuum pump A vacuum pressure control system comprising: a valve; and control means for adjusting a valve opening degree of the vacuum proportional on-off valve based on a vacuum pressure in the reaction chamber and feedback-controlling the vacuum pressure in the reaction chamber to a vacuum target pressure value The position detecting means for changing the output value according to the position of the valve body and outputting the output value when the elastic sealing member loses the sealing force is substantially constant. And the control means Preload the cylinder so that the output value of the position detection means becomes the output value output by the position detection means when the valve body moves to the leak start position at which the elastic seal member loses the sealing force, The lower limit value of the feedback control is used.

(4) According to another aspect of the present invention, a valve body, a valve seat on which the valve body abuts or separates, an elastic seal member mounted on a surface of the valve body that abuts on the valve seat, A vacuum proportional on-off valve having a cylinder for applying a driving force to the valve body and adjusting a minute flow rate by changing a crushing amount of the elastic seal member between the reaction chamber and the vacuum pump, In a vacuum pressure control system that adjusts the valve opening degree of the vacuum proportional on-off valve based on the vacuum pressure of the vacuum chamber, and feedback-controls the vacuum pressure in the reaction chamber to a vacuum target pressure value, output according to the position of the valve body Having a position detecting means for changing the value and outputting, that the output value outputted by the position detecting means when the elastic sealing member loses the sealing force, and the output value of the position detecting means are: The elastic sealing member loses sealing force As the output value the position detecting means outputs when said valve body to leak start position is moved, and preload the cylinder, the lower limit value of the feedback control.

(5) In the invention described in (3) or (4), the position is determined when the cylinder is preloaded from the output value output by the position detecting means when the cylinder is not pressurized to the leak start position. Data storage means for preliminarily storing the fluctuation amount varying up to the output value output by the detection means for each vacuum pressure in the reaction chamber, and obtaining the fluctuation amount according to the vacuum pressure in the reaction chamber from the data storage means Preferably, the leak start position is calculated by adding the obtained fluctuation amount to the output value output by the position detection means.

(6) In the invention described in (5), it is preferable to correct the valve position by detecting the valve position when no pressure is applied and preloading from that position so that a constant lift amount is obtained.

(7) According to another aspect of the present invention, a valve body, a valve seat on which the valve body abuts or separates, an elastic seal member mounted on a surface of the valve body that abuts on the valve seat, A vacuum proportional on-off valve having a cylinder for applying a driving force to the valve body and adjusting a minute flow rate by changing a crushing amount of the elastic seal member between the reaction chamber and the vacuum pump, In the vacuum pressure control program used in a vacuum pressure control system that adjusts the valve opening degree of the vacuum proportional on-off valve based on the vacuum pressure and feedback-controls the vacuum pressure in the reaction chamber to a vacuum target pressure value, The feedback control is performed by calculating a preload pressure value from an indoor vacuum pressure or a target vacuum pressure value, changing a control command, and preloading the cylinder until the pressure measuring means detects the preload pressure value. As the lower limit value, operating the vacuum pressure control system.

(8) According to another aspect of the present invention, a valve body, a valve seat on which the valve body abuts or separates, an elastic seal member attached to a surface of the valve body that abuts on the valve seat, A vacuum proportional on-off valve having a cylinder for applying a driving force to the valve body and adjusting a minute flow rate by changing a crushing amount of the elastic seal member between the reaction chamber and the vacuum pump, In a vacuum pressure control program used in a vacuum pressure control system that adjusts the valve opening of the vacuum proportional on-off valve based on the vacuum pressure of the vacuum chamber and feedback-controls the vacuum pressure in the reaction chamber to a vacuum target pressure value. The output value output by the position detection means when the member loses the sealing force is substantially constant, and the output value of the position detection means that outputs the output value according to the position of the valve body is Elastic seal member seals The valve body is moved to a position where the elastic seal member loses the sealing force by pre-loading the cylinder so that the output value is output by the position detecting means when losing, and the lower limit value of the feedback control. The vacuum pressure control system is operated as follows.

According to the vacuum pressure control system and the vacuum pressure control program of the above aspect, the preload pressure value is calculated from the vacuum pressure in the reaction chamber or the vacuum pressure target value, and the preload pressure value is set as the lower limit value of the feedback control. Therefore, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, the vacuum proportional on-off valve does not cause the valve body to pass excessively beyond the leak start position, and the valve control operation is improved. . Further, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, even when overshoot, hunting, or undershoot occurs, the lower limit value of the feedback control is the leak start position, so the vacuum pressure can be reduced in a short time. Stable and pressure control responsiveness is improved.

According to the vacuum pressure control system and the vacuum pressure control program of the above aspect, when the elastic sealing member loses the sealing force, the position detecting means for changing the output value according to the position of the valve body of the vacuum proportional on-off valve and outputting it The output value output by is almost constant. According to the vacuum pressure control system and the vacuum pressure control program of the above aspect, the cylinder so that the output value of the position detection means becomes the output value output by the position detection means when the elastic seal member loses the sealing force. Is preloaded, and the valve body is moved to a position where the elastic sealing member loses the sealing force, and is set as the lower limit value of the feedback control. Therefore, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, the vacuum proportional on-off valve does not pass through the leak start position and the valve element does not open / close, thereby improving the pressure control responsiveness. Further, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, even when overshoot, hunting, or undershoot occurs, the lower limit value of the feedback control is the leak start position, so the vacuum pressure can be reduced in a short time. Stable and pressure control responsiveness is improved.

According to the vacuum pressure control system of the above aspect, the position detection means outputs when the cylinder is preloaded from the output value output by the position detection means when the cylinder is not pressurized to the position where the elastic seal member loses the sealing force. Data storage means that stores in advance the amount of fluctuation that varies up to the output value for each vacuum pressure in the reaction chamber, obtains the amount of fluctuation corresponding to the vacuum pressure in the reaction chamber from the data storage means, and positions the obtained amount of fluctuation By adding to the output value output by the detection means, the position where the elastic sealing member loses the sealing force is calculated. Therefore, the position at which the elastic sealing member loses the sealing force can be easily calculated from the vacuum pressure in the reaction chamber and the output value of the position detecting means.

According to the vacuum pressure control system of the above aspect, the valve position is corrected by detecting the valve position when no pressure is applied and preloading from that position so as to be a constant lift amount. Therefore, according to the vacuum pressure control system of the above aspect, for example, even when the vacuum proportional on-off valve shifts the valve position by reassembly after maintenance, the lower limit value of the feedback control is corrected according to the shift amount, and the vacuum Pressure control can be performed with high accuracy.

1 is a schematic configuration diagram of a vacuum pressure control system according to a first embodiment of the present invention. It is sectional drawing of the vacuum proportional on-off valve used for a vacuum pressure control system, Comprising: The interruption | blocking state is shown. It is sectional drawing of the vacuum proportional on-off valve used for a vacuum pressure control system, Comprising: A valve open state is shown. It is a control block diagram of a vacuum pressure control system. It is a figure which shows the relationship between a cylinder pressure and the vacuum pressure of a reaction chamber. The vertical axis represents cylinder pressure (kPa), and the horizontal axis represents position sensor output (V). It is a figure which shows the relationship between the cylinder pressure which added the vacuum pressure of the reaction chamber, and a position sensor output. The vertical axis represents the cylinder pressure (kPa, gauge pressure) obtained by adding the vacuum pressure in the reaction chamber, and the horizontal axis represents the position sensor output (V). It is a flowchart of a pressure control program. It is a figure which shows the result of having investigated the pressure control responsiveness of the vacuum pressure control system B. FIG. It is a figure which shows the result of having investigated the pressure control responsiveness of the vacuum pressure control system A. FIG. It is a figure which shows the result of having investigated the pressure control stability of the vacuum pressure control system A, Comprising: The case where a supply flow rate is set to 30 SLM using the PID control constant when supply flow rate is 30 SLM is shown. It is a figure which shows the result of having investigated the pressure control stability of the vacuum pressure control system A, Comprising: The case where a supply flow rate is set to 10 SLM using the PID control constant when supply flow rate is 30 SLM is shown. It is a figure which shows the result of having investigated the pressure control stability of the vacuum pressure control system B, Comprising: The case where a supply flow rate is set to 30 SLM using the PID control constant when supply flow rate is 30 SLM is shown. It is a figure which shows the result of having investigated the pressure control stability of the vacuum pressure control system B, Comprising: The case where a supply flow rate is set to 10 SLM using the PID control constant when supply flow rate is 30 SLM is shown. It is a flowchart of the vacuum pressure control program used with the vacuum pressure control system of 2nd Embodiment of this invention. It is a flowchart of an O ring leak start position calculation program. It is a figure which shows the relationship between a position sensor output and the vacuum pressure of a reaction chamber. The vertical axis represents the position sensor output (V) output from the potentiometer, and the horizontal axis represents the cylinder pressure (kPa, gauge pressure). It is a figure which shows an example of the relationship table of a vacuum pressure and fluctuation amount. It is a figure which shows a mode that the control command lower limit is correct | amended according to a position sensor output, Comprising: A left vertical axis | shaft shows a position sensor output (V), a right vertical axis | shaft shows a control command (V), and a horizontal axis Indicates time sec. It is a figure which shows a mode that a cylinder is pre-pressed, Comprising: The left vertical axis | shaft is the vacuum pressure (x0.133 kPa, absolute pressure) of a reaction chamber, the right vertical axis is cylinder pressure (kPa, gauge pressure), and a horizontal axis is time (sec). ). It is a flowchart of the slow exhaust control program which the vacuum pressure control system which concerns on 3rd Embodiment of this invention performs. It is a figure which shows the time which slow exhaust by the vacuum pressure control system F shows, Comprising: The left vertical axis | shaft shows the vacuum pressure (x0.133 kPa, absolute pressure) of a reaction chamber, and the right vertical axis | shaft shows cylinder pressure (kPa, gauge pressure). ) And the horizontal axis represents time (sec). It is a figure which shows the time which slow exhaust by the vacuum pressure control system G shows, Comprising: The left vertical axis | shaft shows the vacuum pressure (x0.133 kPa, absolute pressure) of a reaction chamber, and the right vertical axis | shaft shows cylinder pressure (kPa, gauge pressure). ) And the horizontal axis represents time (sec). It is a figure which shows the fluctuation | variation of the vacuum pressure and cylinder pressure when an undershoot generate | occur | produces in the vacuum pressure control system F, Comprising: The left vertical axis | shaft shows the vacuum pressure (* 0.133 kPa, absolute pressure) of a reaction chamber, The axis indicates cylinder pressure (kPa, gauge pressure), and the horizontal axis indicates time (sec). It is a figure which shows the fluctuation | variation of the vacuum pressure and cylinder pressure when an undershoot generate | occur | produces in the vacuum pressure control system G, The left vertical axis | shaft shows the vacuum pressure (x0.133 kPa, absolute pressure) of a reaction chamber, The axis indicates cylinder pressure (kPa, gauge pressure), and the horizontal axis indicates time (sec). It is a figure which shows the relationship between the vacuum pressure and control command of the vacuum pressure control system described in patent document 1, Comprising: A left vertical axis | shaft shows a vacuum pressure (x0.133 kPa, absolute pressure), and a right vertical axis | shaft shows a control command. (V) is shown, and the horizontal axis shows time (sec). It is a figure which shows the relationship between the vacuum pressure of the vacuum pressure control system which concerns on 3rd Embodiment, and a control command, Comprising: A left vertical axis | shaft shows a vacuum pressure (x0.133 kPa, absolute pressure), and a right vertical axis | shaft shows a control command. (V) is shown, and the horizontal axis shows time (sec). It is a figure which shows the relationship between the vacuum pressure and cylinder pressure of the vacuum pressure control system described in patent document 1, Comprising: A left vertical axis | shaft shows vacuum pressure (x0.133 kPa, absolute pressure), and a right vertical axis | shaft shows cylinder pressure. (KPa, gauge pressure) is shown, and the horizontal axis shows time (sec). It is a figure which shows the relationship between the vacuum pressure and cylinder pressure of the vacuum pressure control system which concerns on 3rd Embodiment, Comprising: A left vertical axis | shaft shows a vacuum pressure (x0.133 kPa, absolute pressure), and a right vertical axis | shaft shows cylinder pressure. (KPa, gauge pressure) is shown, and the horizontal axis shows time (sec). It is a figure which shows the relationship between the vacuum pressure of the vacuum pressure control system described in patent document 1, and a position sensor output, Comprising: A left vertical axis | shaft shows a vacuum pressure (* 0.133kPa, absolute pressure), and a right vertical axis | shaft is a position. The sensor output (V) is shown, and the horizontal axis shows time (sec). It is a figure which shows the relationship between the vacuum pressure of the vacuum pressure control system which concerns on 3rd Embodiment, and a position sensor output, Comprising: A left vertical axis | shaft shows a vacuum pressure (x0.133kPa, absolute pressure), and a right vertical axis | shaft is a position. The sensor output (V) is shown, and the horizontal axis shows time (sec). It is the figure which showed the outline | summary of the CVD apparatus and its exhaust system. 10 is a flowchart of a slow exhaust control program in a vacuum pressure control system described in Patent Document 1. It is a figure which shows the relationship between the cylinder pressure and valve opening degree of a vacuum proportional on-off valve. The horizontal axis represents time (sec), the left vertical axis in the figure represents the valve opening (mm), and the right vertical axis in the figure represents the cylinder pressure (kPa).

Next, embodiments of a vacuum pressure control system and a vacuum pressure control program according to the present invention will be described with reference to the drawings.

(First embodiment)
<Overall configuration of vacuum pressure control system>
FIG. 1 is a schematic configuration diagram of a vacuum pressure control system according to the first embodiment of the present invention.
The vacuum pressure control system according to the present embodiment sets the lower limit value of the feedback control to the vacuum proportional on / off valve before performing feedback control on the valve on / off operation of the vacuum proportional on / off valve 16 with respect to FIG. 32 shown in the prior art column. These are set individually according to the 16 characteristics. The vacuum pressure control system includes a controller 20 (an example of a control unit), an air pressure control unit 30, a vacuum proportional on-off valve 16 that is an operation unit 40, and vacuum pressure sensors 14 and 15 that are detection units 60.

The controller 20 includes an interface circuit 21, a vacuum pressure control circuit 22, and a sequence control circuit 23. The interface circuit 21 sends a signal by a field input through a button on the front panel of the controller 20 and a signal by a remote input through a connector on the back panel of the controller 20 to the vacuum pressure control circuit 22 or the sequence control circuit 23. It converts to a suitable signal.

The vacuum pressure control circuit 22 is a circuit that performs feedback control with respect to the vacuum pressure in the reaction chamber 10 of FIG. 32 by PID control. The sequence control circuit 23 is predetermined for the drive coil SV1 of the first electromagnetic valve 34 and the drive coil SV2 of the second electromagnetic valve 35 in the pneumatic control unit 30 according to the operation mode given from the interface circuit 21. It is a circuit that operates.

The pneumatic control unit 30 includes a position control circuit 31, a pulse drive circuit 32, a time opening / closing operation valve 33, a first electromagnetic valve 34, and a second electromagnetic valve 35. The position control circuit 31 is a valve opening command value given from the vacuum pressure control circuit 22 and a valve given via the amplifier 19 from a potentiometer 18 (an example of position detection means) provided in the vacuum proportional on-off valve 16. The position of the vacuum proportional on-off valve 16 is controlled by comparing the measured opening value. The pulse drive circuit 32 transmits a pulse signal to the time opening / closing operation valve 33 based on a control signal from the position control circuit 31.

The time opening / closing operation valve 33 incorporates an air supply side proportional valve and an exhaust side proportional valve (not shown), and the air supply side proportional valve and the exhaust side proportional valve are set in response to a pulse signal from the pulse drive circuit 32. A time opening / closing operation for adjusting the air pressure in the pneumatic cylinder 41 (see FIGS. 2 and 3 to be described later) of the vacuum proportional on / off valve 16 via the second solenoid valve 35 and the first solenoid valve 34. It is.
A pressure sensor 50 is disposed between the vacuum proportional on-off valve 16 and the air pressure control unit 30 to measure the cylinder pressure of the vacuum proportional on-off valve 16. The pressure sensor 50 outputs the pressure measurement result to the controller 20.

The vacuum proportional on-off valve 16 serving as the operation unit 40 changes the conductance of the exhaust system from the reaction chamber 10 to the vacuum pump 13 in FIG. 2 and 3 show a cross section of the vacuum proportional on-off valve 16. As shown in FIGS. 2 and 3, a piston rod 43 is provided at the center thereof. The piston 44 is fixed to the piston rod 43 in the pneumatic cylinder 41 that is the upper part of the vacuum proportional on-off valve 16, and the poppet valve body is located in the bellows-type poppet valve 42 that is the lower part of the vacuum proportional on-off valve 16. 45 is fixed. Therefore, the poppet valve body 45 can be moved by the pneumatic cylinder 41. In such a vacuum proportional on-off valve 16, the O-ring 49 is attached to the poppet valve body 45, and the valve-opening operation is performed by bringing the O-ring 49 into contact with or separating from the valve seat 47.

Specifically, in the vacuum proportional on-off valve 16, when compressed air is not supplied into the pneumatic cylinder 41 via the supply port 18A and the inside of the pneumatic cylinder 41 communicates with the exhaust line via the exhaust port 18B, Since the downward urging force of the return spring 46 in the cylinder 41 acts on the piston 44, the poppet valve body 45 is lowered so as to press the O-ring 49 against the valve seat 47 so as to be in close contact with the piston 44 as shown in FIG. The vacuum proportional on-off valve 16 is shut off.

On the other hand, when compressed air is supplied into the pneumatic cylinder 41 via the supply port 18A, the downward urging force by the return spring 46 in the pneumatic cylinder 41 and the upward pressure by the compressed air in the pneumatic cylinder 41 are generated. Since it acts on the piston 44 simultaneously, as shown in FIG. 3, the poppet valve body 45 ascends so as to separate the O-ring 49 from the valve seat 47 and the vacuum proportional on-off valve 16 opens according to the balance. It becomes a state.

Therefore, the distance at which the poppet valve body 45 is separated from the valve seat 47 can be operated by supplying compressed air to the pneumatic cylinder 41 and exhausting it as the lift amount of the valve. The distance at which the poppet valve body 45 is separated from the valve seat 47 is measured by the potentiometer 18 as the lift amount of the valve, and corresponds to the valve opening degree of the vacuum proportional on-off valve 16.

The vacuum pressure sensors 14 and 15 shown in FIG. 1 are capacitance manometers that measure the vacuum pressure in the reaction chamber 10 of FIG. Here, two capacitance manometers are used properly according to the range of the vacuum pressure to be measured.

<Description of operation mode of vacuum pressure control system>
In the vacuum pressure control system according to the present embodiment having such a configuration, the controller 20 can select and set the forced close mode (CLOSE) and the vacuum pressure control mode (PRESS) as operation modes.

In the vacuum pressure control system, when the forced close mode (CLOSE) is selected by the controller 20, the sequence control circuit 23 operates the first electromagnetic valve 34 and the second electromagnetic valve 35 as shown in FIG. Thereby, compressed air is not supplied into the pneumatic cylinder 41, and the pneumatic cylinder 41 communicates with the exhaust line, so that the air pressure in the pneumatic cylinder 41 becomes atmospheric pressure, and the vacuum proportional on-off valve 16 is shut off. .

On the other hand, in the vacuum pressure control system, when the vacuum pressure control mode (PRESS) is selected by the controller 20, the sequence control circuit 23 operates the first electromagnetic valve 34, thereby causing the time opening / closing operation valve 33 and the pneumatic cylinder 41 to operate. Communicate. Thereby, the air pressure in the pneumatic cylinder 41 of the vacuum proportional on-off valve 16 is adjusted, and the lift amount of the valve can be operated by the pneumatic cylinder 41.

When the vacuum pressure control mode is selected, the vacuum pressure control circuit 22 starts feedback control with the target vacuum pressure value designated by the field input or remote input as the target value. That is, in FIG. 32, the vacuum pressure values in the reaction chamber 10 are measured by the vacuum pressure sensors 14 and 15, and the lift of the vacuum proportional on-off valve 16 is lifted according to the difference (control deviation) between the measured value and the target vacuum pressure value. The vacuum pressure in the reaction chamber 10 is kept constant at the target vacuum pressure value by manipulating the amount and changing the conductance of the exhaust system.

Further, when the vacuum pressure control mode is selected, the vacuum pressure control circuit 22 maximizes the feedback control operation amount when the feedback control control deviation is large. It is secured. On the other hand, when the control deviation of the feedback control is small, the time shifts to the time constant adjusted in advance, so that the vacuum pressure in the reaction chamber 10 can be maintained in a stable state.

<Electric configuration of vacuum pressure control system>
Specifically, based on the control block diagram of the vacuum pressure control system shown in FIG. 4, a value obtained by adjusting the vacuum pressure value in the reaction chamber 10 measured by the vacuum pressure sensors 14 and 15 by the proportional differentiation circuits 105 and 106. Is compared with the target vacuum pressure value designated by the field input or remote input, and then input to the proportional differential integration circuits 102 and 103. Thereafter, the integration circuits 104 connected in series output a voltage in the range of 0 to 5 V in order to output to the position control circuit 31. The time constant of the integration circuit 104 is determined by the integration time adjustment circuit 101.

When the measured values of the vacuum pressure sensors 14 and 15 are away from the target vacuum pressure value, the internal arithmetic circuit operates so that the integration time of the integration circuit is minimized. As a result, the integrating circuit 104 functions as an amplifier circuit having an almost infinite gain.

That is,
(Measurement value of vacuum pressure sensors 14 and 15)> (Target vacuum pressure value)
In this case, 5V, which is the maximum value of the integration circuit 104, is output to the position control circuit 31. As a result, the vacuum proportional on-off valve 16 operates in a direction to open rapidly. on the other hand,
(Measurement value of vacuum pressure sensors 14 and 15) <(Target vacuum pressure value)
In this case, 0 V, which is the minimum value of the integration circuit 104, is output to the position control circuit 31. As a result, the vacuum proportional on-off valve 16 operates in a direction to close rapidly.

By these operations, the valve opening degree of the vacuum proportional on-off valve 16 can be reached in the shortest time to the vicinity of the position for obtaining the target vacuum pressure value. After that, the integration time adjusting circuit 101 that has determined that the position has reached the position for achieving the target vacuum pressure value keeps the vacuum pressure at that position in a stable state. Performs an operation that shifts to a constant step by step.

<Relationship between cylinder pressure and vacuum pressure>
FIG. 5 is a diagram showing the relationship between the cylinder pressure and the vacuum pressure in the reaction chamber 10. The vertical axis represents cylinder pressure (kPa), and the horizontal axis represents position sensor output (V).
FIG. 5 shows the pressure sensor 50 (of the pressure measuring means) when the vacuum pressure in the reaction chamber 10 is set to 0 to 800 × 0.133 kPa for the vacuum proportional on-off valve 16 designed to have a collapse amount of the O-ring 49 of 0.500 mm. (Example) shows the cylinder pressure to be measured.

In the vacuum proportional on-off valve 16, since the vacuum pressure acts on the valve body 45, the value (V) of the position sensor output measured by the potentiometer 18 is not measured even when the cylinder pressure is 0 kPa, as indicated by X1 in the figure. It is different. That is, the valve opening is different.

The cylinder pressure when leakage occurs from the O-ring 49 is 139.7 kPa when the vacuum pressure is 0 kPa, 123.3 kPa when the vacuum pressure is 100 × 0.133 kPa, and 109.0 kPa when the vacuum pressure is 200 × 0.133 kPa. When the vacuum pressure is 300 × 0.133 kPa, 97.7 kPa, when the vacuum pressure is 400 × 0.133 kPa, 83.9 kPa, when the vacuum pressure is 500 × 0.133 kPa, 73.4 kPa, and the vacuum pressure is 600 × 0. When the pressure is 133 kPa, the pressure is 59.5 kPa, when the vacuum pressure is 700 × 0.133 kPa, it is 48.4 kPa, and when the vacuum pressure is 800 × 0.133 kPa, the pressure is 33.2 kPa. Thus, in the vacuum proportional on-off valve 16, the cylinder pressure at which leakage occurs from the O-ring 49 varies depending on the vacuum pressure in the reaction chamber 10.

FIG. 6 is a diagram showing the relationship between the cylinder pressure obtained by adding the vacuum pressure in the reaction chamber 10 and the position sensor output. The vertical axis represents the cylinder pressure (kPa) obtained by adding the vacuum pressure in the reaction chamber, and the horizontal axis represents the position sensor output (V).
However, when the vacuum pressure acting on the valve body 45 is added to the cylinder pressure at which leakage occurs from the O-ring 49, the added pressure value is a constant value (140 kPa in this embodiment) as indicated by X2 in the figure. The position sensor output was also found to be constant. Therefore, the position at which leakage starts from the O-ring 49 (leak start position) can be calculated from the cylinder pressure measured by the pressure measurement value and the vacuum pressure.
Here, the vacuum pressure control system stores 125 kpa (considering a margin corresponding to a valve opening of 0.050 mm) in the controller 20 as a leak start position in consideration of variations in the vacuum proportional on-off valve 16 and the pressure sensor 50. is doing.

FIG. 7 is a flowchart of the vacuum pressure control program.
The vacuum pressure control program shown in FIG. 7 is stored in the controller 20 and executed when the vacuum pressure control mode (PRESS) is set, and causes the controller 20 to perform the following processing.

First, in step 20 (hereinafter abbreviated as “S20”), a desired vacuum pressure is acquired.
In S21, the measurement results of the pressure sensors 14 and 15 are acquired, and the vacuum pressure in the reaction chamber 10 is acquired. In S22, the cylinder pressure is acquired from the pressure sensor 50. In S23, the desired vacuum pressure acquired in S20 is compared with the vacuum pressure acquired in S21, and the larger one is subtracted from 125 kPa (example in this embodiment). That is, when the current vacuum pressure is greater than or equal to the desired vacuum pressure (S23; YES), the current vacuum pressure value is subtracted from 125 kPa to calculate the leak position of the O-ring 49 (S231). . On the other hand, when the current vacuum pressure is smaller than the desired vacuum pressure (S23; NO), the desired vacuum pressure value is subtracted from 125 kPa to calculate the leak position of the O-ring 49 (S232). Thereby, the cylinder pressure which becomes the leak start position of the O-ring 49 is calculated.

In S24, it is determined whether or not the current cylinder pressure acquired in S22 is equal to or higher than the cylinder pressure that is the leak start position of the O-ring 49 calculated in S23. If the current cylinder pressure is not equal to or higher than the cylinder pressure at which the O-ring 49 starts leaking (S24: NO), it is considered that the vacuum pressure control system is stopped or temporarily stopped during the vacuum pressure control. The compressed air is supplied and pressurized to the cylinder 41 up to the leak start position of the O-ring 49 acquired in S23, and is set as the lower limit value of the feedback control. Thereafter, in S26, a desired vacuum pressure set in the controller 20 is acquired. In S27, the current vacuum pressure in the reaction chamber 10 is acquired from the pressure sensors 14 and 15. In S28, the vacuum pressure in the reaction chamber 10 is feedback-controlled by adjusting the valve opening degree of the vacuum proportional on-off valve 16 so that the current vacuum pressure approaches the desired vacuum pressure. On the other hand, when the cylinder pressure is equal to or higher than the cylinder pressure at which the O-ring 49 starts leaking (S24: YES), the valve is not closed and the process proceeds to S26.

Such a vacuum pressure control system monitors whether or not the cylinder pressure is equal to or higher than the leak start position of the O-ring 49 when the vacuum pressure is feedback controlled by repeating the processes of S20 to S28. If it is not equal to or higher than the leak start position of the ring 49, the cylinder 41 is pressurized to the leak start position of the O-ring 49 acquired in S23, and the lower limit position of the feedback control is adjusted to the cylinder pressure that becomes the leak start position of the O-ring 49. .

<Pressure control response>
The inventors investigated the pressure control response of the vacuum pressure control system of this embodiment.
In the experiment, a vacuum pressure control system (hereinafter referred to as “vacuum pressure control system A”) in which the valve opening when the cylinder pressure is 0 kPa is the lower limit value of feedback control, and the leak start position of the O-ring 49 are feedback-controlled. This was carried out using the vacuum pressure control system of the present embodiment (hereinafter referred to as “vacuum pressure control system B”) as the lower limit. In the experiment, responsiveness when adjusting the flow rate by reducing the cylinder pressure to 140 kPa and supplying the flow rate supplied to the vacuum proportional on-off valves 16 of the vacuum pressure control systems A and B by increasing the cylinder pressure to 500 kPa. Examined.

FIG. 9 is a diagram showing the results of examining the pressure control responsiveness of the vacuum pressure control system A.
The vacuum pressure control system A reduces the cylinder pressure of the vacuum proportional on-off valve 16 from 500 kPa to 20 kPa, and then adjusts it to 140 kPa. In this case, the vacuum pressure in the reaction chamber 10 caused an overshoot as indicated by X3 in the figure. Further, it takes about 23 seconds for the vacuum pressure in the reaction chamber 10 to stabilize.

FIG. 8 is a diagram showing the results of examining the pressure control responsiveness of the vacuum pressure control system B.
The vacuum pressure control system B reduces the cylinder pressure of the vacuum proportional on-off valve 16 from 500 kPa to 110 kPa, and then adjusts it to 140 kPa. In this case, the vacuum pressure in the reaction chamber 10 does not generate an overshoot as indicated by X4 in the figure. Further, it takes about 20 seconds for the vacuum pressure in the reaction chamber 10 to stabilize.

Therefore, as in this embodiment, the vacuum pressure control system B calculates the leak start position of the O-ring 49 as a lower limit value for feedback control, and uses the valve opening when the cylinder pressure is 0 kPa as the lower limit value for feedback control. Compared with the vacuum pressure control system A, overshoot is less likely to occur. This is presumably because the vacuum pressure control system B has less amount of pressure reduction than the vacuum pressure control system A, and the time for filling the cylinder pressure from the pressure reduction to the target cylinder pressure is short. Further, the vacuum pressure control system B can make the stabilization time of the vacuum pressure in the reaction chamber 10 about 10% faster than the vacuum pressure control system A.

<Pressure control stability>
The inventors investigated the pressure control stability of the vacuum pressure control system of this embodiment.
In the experiment, the vacuum pressure control system A and the vacuum pressure control system B were used. In the experiment, hunting occurs when the same control is performed in the supply flow path 10SLM using the PID control constant when the supply flow rate of each vacuum proportional on-off valve 16 is 30 SML in the vacuum pressure control systems A and B. I investigated whether or not.

FIG. 10 is a diagram showing the results of examining the pressure control stability of the vacuum pressure control system A, and shows the case where the supply flow rate is set to 30 SLM using the PID control constant when the supply flow rate is 30 SLM. FIG. 11 is a diagram showing the results of examining the pressure control stability of the vacuum pressure control system A, and shows the case where the supply flow rate is 10 SLM using the PID control constant when the supply flow rate is 30 SLM.
As shown by X5 in FIG. 10, the vacuum pressure control system A uses the PID control when the supply flow rate is 30 SLM, and when the vacuum proportional on-off valve 16 controls the supply flow rate to 30 SLM, hunting is performed for about 20 seconds. Continue. On the other hand, as shown by X6 in FIG. 11, hunting continues for 100 seconds or more when the vacuum proportional on-off valve 16 controls the supply flow rate to 10 SLM using PID control when the supply flow rate is 30 SLM.

FIG. 12 is a diagram showing the results of examining the pressure control stability of the vacuum pressure control system B, and shows the case where the supply flow rate is set to 30 SLM using the PID control constant when the supply flow rate is 30 SLM. FIG. 13 is a diagram showing the results of examining the pressure control stability of the vacuum pressure control system B, and shows the case where the supply flow rate is 10 SLM using the PID control constant when the supply flow rate is 30 SLM.
When the supply flow rate is controlled to 30 SLM by the vacuum proportional on / off valve 16 using PID control when the supply flow rate is 30 SLM as shown by X7 in FIG. Continue. On the other hand, as indicated by X8 in FIG. 13, when the supply flow rate is controlled to 10 SLM by the vacuum proportional on-off valve 16 using PID control when the supply flow rate is 30 SLM, hunting converges in about 40 seconds.

Therefore, the vacuum pressure control system B can halve the vacuum pressure hunting time as compared with the vacuum pressure control system A. Further, when the supply flow rate is changed from 30 SLM to 10 SLM, the hunting can be suppressed and the vacuum pressure can be controlled without changing the PID control constant. Since changing the PID control constant takes time, it is convenient for the user that the supply flow rate can be changed without changing the PID control constant.

<The effect of the vacuum pressure control system concerning a 1st embodiment>
According to the vacuum pressure control system and the vacuum pressure control program, the preload pressure value (leak start position of the O-ring 49) is calculated from the vacuum pressure in the reaction chamber 10 or the vacuum target pressure value, and the preload pressure value is fed back. The lower limit of control. Therefore, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, the vacuum proportional on-off valve 16 performs the valve opening / closing operation with the valve body 45 passing through the leak start position where the O-ring 49 loses the sealing force. And pressure control response is improved. Further, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, even when overshoot or hunting occurs, the vacuum pressure is stabilized in a short time because the lower limit value of the feedback control is the leak start position. , Pressure control responsiveness is improved.

(Second Embodiment)
Next, the vacuum pressure control system according to the second embodiment will be described.
The vacuum pressure control system according to the second embodiment differs from the first embodiment in that the vacuum pressure control program calculates the leak start position of the O-ring 49 using the position sensor output measured by the potentiometer 18. Therefore, here, the points different from the first embodiment will be mainly described. Note that the same reference numerals as those in the first embodiment are used for the same configurations as those in the first embodiment in the drawings and descriptions, and detailed descriptions thereof are omitted.

<Relationship between position sensor output and reaction chamber pressure>
FIG. 16 is a diagram showing the relationship between the position sensor output and the vacuum pressure in the reaction chamber 10. The vertical axis represents the position sensor output (V) of the potentiometer 18, and the horizontal axis represents the cylinder pressure (kPa).
FIG. 16 shows a valve that causes leakage from the O-ring 49 when the vacuum pressure in the reaction chamber 10 is set to 0 to 800 × 0.133 kPa with respect to the vacuum proportional on-off valve 16 designed to have a crushing amount of the O-ring 49 of 0.500 mm. It is a figure which shows the result of having measured the position (valve opening degree) of the body 45, and the position sensor output which the potentiometer 18 outputs.

Since the vacuum proportional on-off valve 16 applies a vacuum pressure to the valve body 45, the position sensor output (V) of the potentiometer 18, that is, the valve opening degree, even if the cylinder pressure is 0 kPa, as indicated by X9 in the figure. Depends on the vacuum pressure in the reaction chamber 10.
The numerical value in the figure indicates the position sensor output when leakage occurs from the O-ring 49. The position sensor output when a leak occurs from the O-ring 49 is 1.264 V when the vacuum pressure is 0 kPa, 1.265 V when the vacuum pressure is 100 × 0.133 kPa, and 1 when the vacuum pressure is 200 × 0.133 kPa. 263 V, 1.264 V when the vacuum pressure is 300 × 0.133 kPa, 1.262 V when the vacuum pressure is 400 × 0.133 kPa, 1.264 V when the vacuum pressure is 500 × 0.133 kPa, and 600 × 0. When the pressure is 133 kPa, it is 1.261 V, when the vacuum pressure is 700 × 0.133 kPa, it is 1.263 V, and when the vacuum pressure is 800 × 0.133 kPa, it is 1.260 V. Thus, the vacuum proportional on-off valve 16 is stable at a position sensor output of about 1.263 V when leakage occurs from the O-ring 49.

Therefore, if the amount of variation from the position sensor output when the cylinder pressure is 0 kPa to the position sensor output when the O-ring 49 begins to leak is stored in the controller 20 in advance for each vacuum pressure, the controller 20 can store the fluctuation amount when the cylinder pressure is 0 kPa. The leak start position of the O-ring 40 can be calculated by adding the amount of fluctuation corresponding to the vacuum pressure to the measured position sensor output.
For example, when the vacuum pressure is 0 kPa, the fluctuation amount of the position sensor output is 1.200 V when the cylinder pressure is 0 kPa, and 1.264 V at the leak start position of the O-ring 46. The difference is 0.064V. When the potentiometer 18 having a position sensor output of 0.001 V corresponding to about 0.0078 mm as the valve opening is used, the position sensor output fluctuation of 0.064 V corresponds to the valve opening fluctuation of 0.498 mm. The variation amount 0.498 mm of the valve opening degree substantially coincides with the crushing amount 0.500 mm of the O-ring 49. Therefore, the fluctuation amount of the valve opening can be recognized from the fluctuation amount of the position sensor output.

<Vacuum pressure and variation table>
Therefore, the vacuum pressure control system stores a relationship table between the vacuum pressure and the fluctuation amount in the controller 20. FIG. 17 is a diagram illustrating an example of a relationship table between the vacuum pressure and the fluctuation amount.
The table considers a margin for the valve opening 0.100 mm (position sensor output 13 mV) in the valve opening fluctuation amount and the position sensor output fluctuation amount calculated for each vacuum pressure from the measurement results shown in FIG. Thus, the variation amount of the valve opening and the variation amount of the position sensor output are stored.
FIG. 14 is a flowchart of the vacuum pressure control program.
The vacuum pressure control program is stored in the controller 20 and is executed when the vacuum pressure control mode (PRESS) is set, and causes the controller 20 to perform the following processing.
First, in S21, the measurement results of the pressure sensors 14 and 15 are acquired, and the vacuum pressure in the reaction chamber 10 is acquired. In S32, the current valve opening is acquired from the position sensor output of the potentiometer 18. In S33, the leak start position of the O-ring 49 is calculated from the vacuum pressure acquired in S21 and the position sensor output acquired in S32.

FIG. 15 is a flowchart of the O-ring leak start position calculation program.
The O-ring leak start position is calculated by executing the process shown in FIG. Specifically, in S41, it is detected whether or not the vacuum proportional on-off valve 16 is in a closed state. When the vacuum proportional on-off valve 16 is not in the closed state (S41: NO), the leak start position of the O-ring 49 stored in the controller 20 is adopted in S45, and the process proceeds to S24 in FIG.
On the other hand, when the vacuum proportional on-off valve 16 is in the closed state (S41: YES), in S42 of FIG. 15, the fluctuation of the position sensor output from the table shown in FIG. Get by referring to the amount. In S43, the leak start position of the O-ring 49 is calculated by adding the fluctuation amount of the position sensor output acquired in S42 to the current position sensor output acquired in S32. In S44, the leak start position of the O-ring 49 calculated in S43 is updated / saved in the controller 20. Thereafter, the process proceeds to S24 of FIG.

In S24, it is determined whether or not the current valve opening is equal to or greater than the leak start position of the O-ring 49. This determination is made based on whether or not the current position sensor output acquired in S32 is equal to or greater than the leak start position of the O-ring 49 stored in the controller 20. If the current position sensor output is not equal to or higher than the leak start position of the O-ring 49 (S24: NO), the supply port 18A is supplied until the potentiometer 18 measures the leak start position of the O-ring 49 acquired in S23 in S25. Compressed air is supplied to pressurize the cylinder 41. Thereby, the lower limit value of the feedback control is adjusted. Thereafter, S26 to S28 are the same as those in the first embodiment, and thus the description thereof is omitted.

Such a vacuum pressure control system monitors whether or not the valve opening (position sensor output) is equal to or greater than the leak start position of the O-ring 49 when the vacuum pressure is feedback controlled by repeating the processes of S24 to S28. If the position sensor output is not equal to or higher than the leak start position of the O-ring 49, the cylinder 41 is pressurized to the leak start position of the O-ring 49 stored in the controller 20, and the lower limit position of the feedback control is set to the O-ring 49. Adjust to the leak start position.

<About correction>
By the way, the valve position of the vacuum proportional on-off valve 16 is normal when the cylinder pressure is 0 kPa due to a change in valve position due to reassembly after valve maintenance, a mechanical shift with time, and a change in valve position due to product adhesion. May deviate from valve position. Even in this case, the vacuum pressure control system is the position sensor output fluctuation amount considering the collapse amount of the O-ring 49 in the position sensor output measured by the potentiometer 18 when the cylinder pressure is 0 kPa and the vacuum proportional on-off valve 16 is closed. Is added to correct the leak start position of the O-ring 49.

<Relationship between position sensor output and control command>
In the experiment, when the vacuum proportional on-off valve 16 is changed from the open state to the closed state, the position sensor output of the potentiometer 18 is 1.145 V, and when the vacuum proportional on-off valve 16 is changed from the open state to the closed state. A vacuum pressure control system D in which the position sensor output of the potentiometer 18 is 1.240 V, and a vacuum pressure control system E in which the position sensor output of the potentiometer 18 is 1.335 V when the vacuum proportional on-off valve 16 is changed from the open state to the closed state. Were used to control the vacuum pressure in the reaction chamber 10 to the target pressure (here, 9.0 × 0.133 kPa). In this case, the vacuum pressure control system C to E outputs a control command (V) output to the vacuum proportional on / off valve 16, a position sensor output (V) output from the potentiometer 18, and a cylinder pressure ( kPa) and the vacuum pressure (kPa) in the reaction chamber 10 were measured. The experimental results are shown in FIGS.

FIG. 18 is a diagram showing how the control command lower limit value is corrected in accordance with the position sensor output. The left vertical axis indicates the position sensor output (V), and the right vertical axis indicates the control command (V). The horizontal axis indicates time sec.
The control commands given to the vacuum proportional on-off valve 16 by the vacuum pressure control systems C to E correspond to the position sensor output linearly. Therefore, the control command also changes in accordance with the position sensor output, and the control command lower limit value is a different value depending on the position sensor output at that time. Therefore, it can be seen from the measurement results shown in FIG. 18 that the vacuum pressure control systems C to E correct the control command in accordance with the position sensor output at the time of closing.

<Relationship between position sensor output and cylinder pressure>
FIG. 19 is a diagram showing a state in which the cylinder is preloaded, the left vertical axis is the vacuum pressure (× 0.133 kPa, absolute pressure) of the reaction chamber 10, the right vertical axis is the cylinder pressure (kPa, gauge pressure), and the horizontal The axis indicates time (sec).
In the vacuum pressure control systems C to E in which the control commands are corrected as described above, the position sensor output when the vacuum proportional on-off valve 16 is closed is different from 1.145V, 1.240V, and 1.335V. The cylinder 41 is preloaded with the same pressure.

<Specific examples for setting the lower limit of control commands>
Next, a specific example of setting a lower limit value of a control command output to the vacuum proportional on-off valve 16 when the vacuum pressure control system performs feedback control will be described.
For example, when the current vacuum pressure measured by the pressure sensors 14 and 15 is 0 kPa and the position sensor output of the potentiometer 18 is 1.203 V when the vacuum proportional on-off valve 16 is closed, The position sensor output is 0.003V larger than the normal position sensor output reference value (1.200V) shown in part X9 in FIG. That is, the valve opening is larger than that at the normal time. In this case, the position sensor output reference value 0.051 V when the vacuum pressure is 0 kPa shown in FIG. 17 is read out and added to the position sensor output (1.203 V). Thereby, the leak start position of the O-ring 49 is corrected to a position where the position sensor output outputs 1.254V.

For example, when the vacuum proportional on-off valve 16 is closed, the current vacuum pressure measured by the pressure sensors 14 and 15 is 0 kPa, and the position sensor output of the potentiometer 18 is 1.213V. The position sensor output is 0.013 V larger than the position sensor output reference value (1.200 V) when the vacuum pressure is 0 kPa shown in part X9 of FIG. In this case, the position sensor output reference value 0.051 V when the vacuum pressure is 0 kPa shown in FIG. 17 is read out and added to the position sensor output (1.213 V). Accordingly, the leak start position of the O-ring 49 is corrected to a position where the position sensor output outputs 1.264V.

Furthermore, when the current vacuum pressure measured by the pressure sensors 14 and 15 is 0 kPa and the position sensor output of the potentiometer 18 is 1.193 V when the vacuum proportional on-off valve 16 is closed, The position sensor output is 0.007V smaller than the position sensor output reference value (1.200V) when the vacuum pressure is 0 kPa shown in the X9 part of FIG. In this case, the position sensor output reference value 0.051 V when the vacuum pressure is 0 kPa shown in FIG. 17 is read and added to the position sensor output (1.193 V). Accordingly, the leak start position of the O-ring 49 is corrected to a position where the position sensor output outputs 1.244V.

Further, when the vacuum proportional on-off valve 16 is closed, the current vacuum pressure measured by the pressure sensors 14 and 15 is 100 × 0.133 kPa, and the position sensor output of the potentiometer 18 is 1.210V. In this case, the position sensor output is 0.010 V smaller than the position sensor output reference value (1.220 V) when the vacuum pressure is 100 × 0.133 kPa shown in the X9 part of FIG. In this case, the position sensor output reference value 0.045 V when the vacuum pressure is 100 × 0.133 kPa shown in FIG. 17 is read out and added to the position sensor output (1.210 V). Thereby, the leak start position of the O-ring 49 is corrected to a position where the position sensor output outputs 1.255V.

<Operational Effect of Vacuum Pressure Control System According to Second Embodiment>
According to the vacuum pressure control system and the vacuum pressure control program of the above aspect, when the O-ring 49 loses the sealing force, the potentiometer that changes the output value according to the position of the valve body 45 of the vacuum proportional on-off valve 16 and outputs it. The output value (position sensor output) output by 18 is substantially constant. According to the vacuum pressure control system and the vacuum pressure control program of the above aspect, the potentiometer 18 outputs the output value of the potentiometer 18 when the valve body 45 moves to the leak start position where the O-ring 49 loses the sealing force. The cylinder 41 is preloaded so as to obtain an output value, and is set as the lower limit value of the feedback control. Therefore, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, the vacuum proportional on-off valve 16 does not cause the valve body 45 to pass through the leakage start position and the valve opening / closing operation is performed, and the pressure control responsiveness is improved. improves. Further, according to the vacuum pressure control system and the vacuum pressure control program of the above aspect, even when overshoot or hunting occurs, the lower limit value of the feedback control is the leak start position, so the vacuum pressure is stabilized in a short time, Pressure control response is improved.

According to the vacuum pressure control system of the above aspect, the O-ring 49 leaks the cylinder 41 from the position sensor output output by the potentiometer 18 when the cylinder 41 is not pressurized (when the cylinder pressure is 0 kPa). It has data storage means (table) for storing the amount of fluctuation that varies up to the position sensor output output by the potentiometer 18 when preloading to the start position, according to the vacuum pressure in the reaction chamber 10, and according to the vacuum pressure in the reaction chamber 10. The obtained fluctuation amount is obtained from the table, and the obtained fluctuation amount is added to the position sensor output output from the potentiometer 18, thereby calculating the position where the O-ring 49 loses the sealing force (leak start position). Therefore, the leak start position at which the O-ring 49 loses the sealing force can be easily calculated from the vacuum pressure in the reaction chamber 10 and the position sensor output from the potentiometer 18.

According to the vacuum pressure control system of the above aspect, the fluctuation amount corresponding to the vacuum pressure in the reaction chamber 10 is added to the output value detected by the potentiometer 18 when the cylinder 41 is not pressurized. Even if the output of the position sensor is deviated during the period, the correction means for correcting the leak start position of the O-ring 49 is provided by the deviation. Therefore, according to the vacuum pressure control system of the above aspect, for example, even when the vacuum proportional on-off valve 16 shifts the valve position by reassembly after maintenance, the lower limit value of the feedback control is corrected according to the shift amount, Vacuum pressure control can be performed with high accuracy.

(Third embodiment)
Next, a vacuum pressure control system according to the third embodiment of the present invention will be described.
The vacuum pressure control system of the third embodiment is different from the first embodiment in that it includes a slow exhaust mode in which gas is slowly exhausted from the reaction chamber 10. Therefore, here, the description will focus on the differences from the first embodiment. About the point which is common in 1st Embodiment, the same code | symbol as 1st Embodiment is used for drawing and description, and detailed description is abbreviate | omitted.

<Slow exhaust control program>
FIG. 20 is a flowchart of a slow exhaust control program executed by the vacuum pressure control system.
The slow exhaust control program is stored in the controller 20 of the vacuum pressure control system. When the slow exhaust mode is set, the vacuum pressure control system causes the controller 20 to execute the slow exhaust control program shown in FIG. 20 and performs the following processing.
When the vacuum proportional on-off valve 16 is closed, the vacuum pressure control system acquires the current vacuum pressure and valve opening, and calculates the leak start position of the O-ring 49 (S201: YES, S21). , S52, S53). The valve opening degree and the leak start position of the O-ring 49 may be detected by the cylinder pressure as in the first embodiment, or may be acquired by the position sensor output of the potentiometer 18 as in the second embodiment. On the other hand, when the vacuum proportional on-off valve 16 is not closed (S201: NO), the stored leak position of the O-ring 49 is employed.

In S24, it is determined whether or not the current valve opening is equal to or greater than the leak start position of the O-ring 49. If the current valve opening is not equal to or greater than the leak start position of the O-ring 49 (S24: NO), in S25, the cylinder 41 is pressurized to the leak start position of the O-ring 49 acquired in S53, and the lower limit value of feedback control. Adjust. Thereafter, the process proceeds to S109. On the other hand, if the current position sensor output is greater than or equal to the leak start position of the O-ring 49 (S24: YES), the process proceeds directly to S109.

Since S109 and subsequent steps are the same as the prior art, the description thereof is omitted. The vacuum pressure control system repeats the processes of S24, S25, and S109 to S115, and feedback-controls the vacuum pressure in the reaction chamber 10. At this time, the vacuum pressure control system sets the cylinder so that the valve opening degree is not equal to or greater than the leak start position of the O-ring 49 and the valve opening degree is the O-ring leak start position when the vacuum proportional on-off valve 16 is closed. Since 41 is in a preload state, the valve opening is not made excessively smaller than necessary during feedback control.

<About slow exhaust time>
The inventors investigated the effect of cylinder preload on the slow exhaust time.
In the experiment, a vacuum pressure control system F in which the lower limit value of the feedback control is a cylinder pressure at a cylinder pressure of 0 kPa and a vacuum pressure control system G in which the lower limit value of the feedback control is the leak start position of the O-ring 49 are used. went. In the experiment, the vacuum pressure control systems F and G adjust the valve opening degree of the vacuum proportional on-off valve 16 so as to depressurize the reaction chamber 10 at a set flow rate (here, 0.333 kPa / sec), Cylinder pressure was measured over time. The experimental results are shown in FIGS.

FIG. 21 is a diagram showing the time required for slow evacuation by the vacuum pressure control system F. The left vertical axis indicates the vacuum pressure (× 0.133 kPa, absolute pressure) in the reaction chamber 10, and the right vertical axis indicates the cylinder pressure. (KPa, gauge pressure) is shown, and the horizontal axis shows time (sec).
It took 9 seconds for the vacuum pressure control system F to adjust the valve opening degree of the vacuum proportional on-off valve 16 so as to depressurize the reaction chamber 10 at the target flow rate.
FIG. 22 is a diagram showing the time required for slow evacuation by the vacuum pressure control system G. The left vertical axis indicates the vacuum pressure (× 0.133 kPa, absolute pressure) in the reaction chamber 10, and the right vertical axis indicates the cylinder pressure. (KPa, gauge pressure) is shown, and the horizontal axis shows time (sec).
It took 6 seconds for the vacuum pressure control system G to adjust the valve opening degree of the vacuum proportional on-off valve 16 so as to depressurize the reaction chamber 10 at the target flow rate.
Therefore, the vacuum pressure control system G was able to reduce the time required for slow exhausting to two thirds than the vacuum pressure control system F. This is because the vacuum pressure control system G preloads the cylinder 41 to the leak start position of the O-ring 49, and simultaneously supplies compressed air to the supply port 18A of the vacuum proportional on-off valve 16, and gas is supplied to the vacuum proportional on-off valve 16 at the same time. It is thought to begin to flow.

<Control when undershoot occurs>
The inventors investigated the control when undershoot occurred during slow exhaust using the vacuum pressure control systems F and G. In the experiment, the opening degree of the vacuum proportional on-off valve 16 is adjusted so that the vacuum pressure control systems F and G depressurize the reaction chamber 10 at a set flow rate (here, 0.333 kPa / sec), and the reaction chamber 10 depressurizes. When starting, the cylinder 41 is pressurized to cause undershoot. In this case, the vacuum pressure and cylinder pressure of the vacuum pressure control systems F and G were measured over time. The experimental results are shown in FIGS.

FIG. 23 is a diagram showing fluctuations in vacuum pressure and cylinder pressure when undershoot occurs in the vacuum pressure control system F. The left vertical axis represents the vacuum pressure in the reaction chamber 10 (× 0.133 kPa, absolute pressure). The right vertical axis represents cylinder pressure (kPa, gauge pressure), and the horizontal axis represents time (sec).
The vacuum pressure control system F had a maximum cylinder pressure fluctuation of about 70 kPa, and it took about 30 seconds to stabilize the cylinder pressure. In the reaction chamber 10, an undershoot of −27.5 × 0.133 kPa occurred, and it took about 40 seconds to stabilize after the undershoot occurred.

FIG. 24 is a diagram showing fluctuations in vacuum pressure and cylinder pressure when undershoot occurs in the vacuum pressure control system G, and the left vertical axis represents the vacuum pressure in the reaction chamber 10 (× 0.133 kPa, absolute pressure). The right vertical axis represents cylinder pressure (kPa, gauge pressure), and the horizontal axis represents time (sec).
The vacuum pressure control system G had a maximum cylinder pressure fluctuation of about 30 kPa and took about 15 seconds to stabilize the cylinder pressure. In the reaction chamber 10, an undershoot of −9.0 × 0.133 kPa occurred, and it took about 15 seconds to stabilize after the undershoot occurred.

Thus, in the vacuum pressure control system G, the cylinder pressure fluctuation at the time of undershooting is smaller by more than half than the vacuum pressure control system F, and the time required for the cylinder pressure to be stabilized is also shortened by about half. Then, the vacuum pressure control system G can suppress the undershoot generated in the reaction chamber 10 to about one third, and the time for the vacuum pressure to stabilize after the occurrence of the undershoot can be shortened by more than half than the vacuum pressure control system F. This is because when the vacuum pressure control system G reduces the flow rate to the vacuum proportional on-off valve 16, the valve body 45 is moved only to the leak start position of the O-ring 49, and thus follows the pressure fluctuation in the reaction chamber 10. It is considered that the flow rate can be controlled with good responsiveness by opening and closing the vacuum proportional on-off valve 16.

<The effect of the vacuum pressure control system concerning a 3rd embodiment>
The vacuum pressure control system according to the third embodiment can improve the pressure control response as in the first embodiment. Further, in the vacuum pressure control system according to the third embodiment, even when undershoot occurs, the lower limit value of the feedback control is the leak start position at which the O-ring 49 loses the sealing force. Stable and pressure control responsiveness is improved.
Here, the vacuum pressure control system according to the third embodiment and the vacuum pressure control system described in Patent Document 1 are related to the relationship between the vacuum pressure and the control command, the relationship between the vacuum pressure and the cylinder pressure, the vacuum pressure and the position sensor output. The difference between the two is clarified.

In the experiment, the vacuum pressure control system described in Patent Document 1 and the vacuum pressure control system of the third embodiment were caused to perform slow exhaust at a set flow rate of 2.5 × 0.133 kPa / sec, Control command fluctuation, cylinder pressure fluctuation, and position sensor output fluctuation were investigated. The results of this experiment are shown in FIGS.
FIG. 25 is a diagram showing the relationship between the vacuum pressure and the control command of the vacuum pressure control system described in Patent Document 1, wherein the left vertical axis shows the vacuum pressure (× 0.133 kPa, absolute pressure), and the right vertical The axis indicates the control command (V), and the horizontal axis indicates time (sec).
The vacuum pressure control system described in Patent Literature 1 applies a preload to the cylinder 41 in order to eliminate the dead zone of the vacuum proportional on-off valve 16. However, since the leak start position of the O-ring 49 is unknown, the amount of preload that can be preloaded on the cylinder 41 is unknown. Therefore, as shown in S103 and S108 in FIG. 32, preloading is performed by adjusting the valve opening stepwise while checking the vacuum pressure fluctuation for a specified time (10 sec) (A part in FIG. 25). By performing feedback control for a specified time (10 sec) (B section in FIG. 25), the preload possible amount is obtained. For this reason, the vacuum pressure control system described in Patent Document 1 requires a maximum of 20 seconds for the preload, takes 29.6 seconds to stabilize the flow rate of the slow exhaust, and has poor control response.

FIG. 26 is a diagram showing the relationship between the vacuum pressure and the control command of the vacuum pressure control system according to the third embodiment, wherein the left vertical axis shows the vacuum pressure (× 0.133 kPa, absolute pressure), and the right vertical The axis indicates the control command (V), and the horizontal axis indicates time (sec).
The vacuum pressure control system of the third embodiment calculates the leak opening position of the O-ring 49 from the vacuum pressure or the vacuum pressure target, or adds the position sensor output fluctuation amount to the position sensor output value to leak the O-ring 49. The start position is calculated, and the preload possible amount of the cylinder 41 is obtained. Therefore, since compressed air can be supplied to the cylinder 41 to the leak start position of the O-ring 49 and the cylinder 41 can be preloaded at once, the preload time is short, and the flow rate of the slow exhaust only takes 9.2 seconds, and control response Is good.

FIG. 27 is a diagram showing the relationship between the vacuum pressure and the cylinder pressure of the vacuum pressure control system described in Patent Document 1, wherein the left vertical axis shows the vacuum pressure (× 0.133 kPa, absolute pressure), and the right vertical The axis indicates cylinder pressure (kPa, gauge pressure), and the horizontal axis indicates time (sec).
The vacuum pressure control system described in Patent Document 1 hardly preloads the cylinder 41 in the A part and the B part in the figure for adjusting the preload possible amount.
FIG. 28 is a diagram showing the relationship between the vacuum pressure and the cylinder pressure in the vacuum pressure control system according to the third embodiment, in which the left vertical axis represents the vacuum pressure (× 0.133 kPa, absolute pressure), and the right vertical The axis indicates cylinder pressure (kPa, gauge pressure), and the horizontal axis indicates time (sec).
The vacuum pressure control system according to the third embodiment starts to preload the cylinder 41 simultaneously with the start of slow exhaust.

FIG. 29 is a diagram showing the relationship between the vacuum pressure and the position sensor output of the vacuum pressure control system described in Patent Document 1, and the left vertical axis shows the vacuum pressure (× 0.133 kPa, absolute pressure), and the right side The vertical axis represents the position sensor output (V), and the horizontal axis represents time (sec).
In the vacuum pressure control system described in Patent Document 1, the position sensor output hardly changes in the A part and B part in the figure for adjusting the preload possible amount. That is, the valve opening does not change.
FIG. 30 is a diagram illustrating the relationship between the vacuum pressure and the position sensor output of the vacuum pressure control system according to the third embodiment, in which the left vertical axis represents the vacuum pressure (× 0.133 kPa, absolute pressure), and the right side The vertical axis represents the position sensor output (V), and the horizontal axis represents time (sec).
In the vacuum pressure control system according to the third embodiment, the position sensor output changes simultaneously with the slow exhaust. That is, the valve opening is changing.

As described above, the vacuum pressure control system of the third embodiment improves the control response by adjusting the lower limit value of the feedback control to the O-ring leak start position, and adjusts the preload of the cylinder 41 and the valve opening degree. This can be done immediately after the start of slow exhaust, and there is no waste. In particular, if the semiconductor manufacturing apparatus can shorten the control responsiveness and preload time of the vacuum pressure control system, it can manufacture products during the shortened time, and can manufacture more products.

In addition, this invention is not limited to the said embodiment, Various application is possible.
For example, in this embodiment, the preload pressure value is calculated from the experimental data, but may be calculated based on the design value of the collapse amount of the O-ring. Or you may calculate based on the cylinder pressure when the amount of squashing of an O-ring becomes a predetermined value (for example, 0.500 mm).
In this embodiment, the preload pressure value is stored in advance, but a system that automatically detects the cylinder pressure or the like may be employed.

In the above embodiment, the vacuum pressure control program and the slow exhaust control program are stored in the controller 20 provided individually outside the vacuum proportional on-off valve 16. On the other hand, a vacuum controller or a slow exhaust control program is read by a control controller (for example, a controller of a semiconductor manufacturing apparatus) provided outside the vacuum pressure control system, and the vacuum pressure control is performed using the controller. The system operation may be controlled. A controller 20 may be provided in the vacuum proportional on-off valve 16.
Further, for example, when the leak start position of the O-ring 49 is calculated based on the position sensor output of the potentiometer 18 and the vacuum pressure in the reaction chamber 10 as in the second embodiment, the pressure sensor 50 is omitted to reduce the cost. May be.
For example, what measures a valve opening degree by detecting the magnet provided in the piston is good also as an example of a position measurement means.

10 reaction chamber 13 vacuum pump 16 vacuum proportional on-off valve 18 potentiometer (an example of position detecting means)
20 controller (an example of control means)
41 Cylinder 45 Valve body 47 Valve seat 49 O-ring 50 Pressure sensor (an example of pressure measuring means)

Claims (5)

A valve body; a valve seat on which the valve body abuts or separates; an elastic seal member mounted on a surface of the valve body that abuts on the valve seat; and a cylinder that applies driving force to the valve body. Then, the minute flow rate is adjusted by changing the crushing amount of the elastic seal member, and based on the vacuum proportional on-off valve disposed between the reaction chamber and the vacuum pump, and the vacuum pressure in the reaction chamber, A vacuum pressure control system comprising: a control unit that adjusts a valve opening of the vacuum proportional on-off valve and feedback-controls the vacuum pressure in the reaction chamber to a vacuum target pressure value;
Having position detecting means for changing and outputting an output value according to the position of the valve body;
The output value output by the position detecting means when the elastic sealing member loses the sealing force is substantially constant;
The control means is configured so that the output value of the position detection means becomes an output value output by the position detection means when the valve body moves to a leak start position at which the elastic seal member loses sealing force. Preload the cylinder to the lower limit of the feedback control;
Features a vacuum pressure control system. A valve body; a valve seat on which the valve body abuts or separates; an elastic seal member mounted on a surface of the valve body that abuts on the valve seat; and a cylinder that applies driving force to the valve body. A vacuum proportional on-off valve that adjusts a minute flow rate by changing a crushing amount of the elastic seal member is disposed between the reaction chamber and the vacuum pump, and the vacuum proportional on-off valve is based on the vacuum pressure in the reaction chamber. In a vacuum pressure control system that adjusts the valve opening of the reaction chamber and feedback-controls the vacuum pressure in the reaction chamber to a vacuum target pressure value,
Having position detecting means for changing and outputting an output value according to the position of the valve body;
The output value output by the position detecting means when the elastic sealing member loses the sealing force is constant;
Preload the cylinder so that the output value of the position detection means becomes the output value output by the position detection means when the valve body moves to the leak start position where the elastic seal member loses the sealing force. A lower limit value of the feedback control,
Features a vacuum pressure control system. In the vacuum pressure control system according to claim 1 or 2,
The amount of fluctuation that varies from the output value output by the position detection means when the cylinder is not pressurized to the output value output by the position detection means when the cylinder is preloaded to the leak start position is expressed as the reaction. Data storage means for storing in advance for each vacuum pressure in the room,
Obtaining the fluctuation amount according to the vacuum pressure of the reaction chamber from the data storage means, and calculating the leak start position by adding the obtained fluctuation amount to an output value output by the position detection means. Features vacuum pressure control system. The vacuum pressure control system according to claim 3,
A vacuum pressure control system for correcting a valve position by detecting a valve position when no pressure is applied and preloading from that position so as to be a constant lift amount. A valve body; a valve seat on which the valve body abuts or separates; an elastic seal member mounted on a surface of the valve body that abuts on the valve seat; and a cylinder that applies driving force to the valve body. A vacuum proportional on-off valve that adjusts a minute flow rate by changing a crushing amount of the elastic seal member is disposed between the reaction chamber and the vacuum pump, and the vacuum proportional on-off valve is based on the vacuum pressure in the reaction chamber. In a vacuum pressure control program used in a vacuum pressure control system that adjusts the valve opening of the reaction chamber and feedback-controls the vacuum pressure in the reaction chamber to a vacuum target pressure value,
The output value output by the position detecting means when the elastic sealing member loses the sealing force is substantially constant;
The output value of the position detection means that outputs the output value by changing the output value according to the position of the valve body is the output value that the position detection means outputs when the elastic seal member loses the sealing force. Operating the vacuum pressure control system to move the valve body to a position where the elastic sealing member loses the sealing force by preloading the cylinder, and set the lower limit value of the feedback control;
A vacuum pressure control program characterized by

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