CN114484040A - Valve control device and vacuum valve - Google Patents

Abstract

The invention provides a valve control device and a vacuum valve capable of shortening pressure regulating time. A valve control device (2) controls the opening degree of a vacuum valve installed in a vacuum chamber by opening control, and the valve control device (2) includes: a feedforward controller (220) that outputs an opening degree set value (θ 1) for opening control; and a pressure regulation controller (21) that determines, during a predetermined period within a fixed period in which the opening degree set value (θ 1) becomes a fixed value, that the pressure balance value for the case of the fixed value does not exceed the valve control pressure target value (Ps). When it is determined that the pressure balance value does not exceed the pressure target value (Ps), the pressure regulation controller (21) controls the opening degree based on the determination result.

Description

Valve control device and vacuum valve

Technical Field

The present invention relates to a valve control device and a vacuum valve.

Background

In a vacuum processing apparatus such as a Chemical Vapor Deposition (CVD) apparatus, a vacuum valve for pressure adjustment is provided between a process chamber and a vacuum pump (see, for example, patent document 1), and the chamber pressure is automatically adjusted to a predetermined pressure by controlling the opening degree of the vacuum valve. The vacuum valve described in patent document 1 is roughly adjusted to a pressure target value by an open control (open control), and is switched to a close control (close control), and approaches the pressure target value by a fine adjustment.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2018-106718

Disclosure of Invention

[ problems to be solved by the invention ]

In the invention described in patent document 1, when the opening degree is in a fixed state during opening control, it is determined whether the pilot pressure Pp exceeds the target pressure value Ps (Pp > Ps) or does not exceed the target pressure value Ps (Pp Ps). However, in the determination that the predicted pressure Pp does not exceed the pressure target value Ps, it is difficult to recognize that the predicted pressure Pp does not exceed the pressure target value Ps in a stage where the predicted pressure Pp tends to rise. As a result, the voltage regulation time is unnecessarily long.

[ means for solving the problems ]

A valve control device according to a first aspect of the present invention controls an opening degree of a vacuum valve attached to a vacuum chamber by opening control, and includes: an opening setting unit that outputs an opening set value for opening control; a first determination unit that determines that a pressure balance value in a case where the opening degree set value is a fixed value does not exceed a target valve control pressure value during a predetermined period within a fixed period in which the opening degree set value is the fixed value; and an opening degree control unit that controls the opening degree based on the determination result of the first determination unit.

A vacuum valve according to a second aspect of the present invention includes: a valve body; a valve body driving part for driving the valve body; and the valve control device controls the valve body driving part to control the opening degree of the valve body.

[ Effect of the invention ]

According to the invention, the voltage regulation time can be shortened.

Drawings

Fig. 1 is a block diagram showing a schematic configuration of a vacuum valve attached to a vacuum processing apparatus.

Fig. 2 is a functional block diagram of a vacuum valve and a valve control device.

Fig. 3 is a diagram illustrating voltage regulation logic under open control.

Fig. 4 shows an example of the locus of the points (θ r, Pr) obtained by the open control.

Fig. 5 is a graph illustrating the relationship between the pressure measurement value Pr and the predicted pressure Pp, and shows a case where Pe (θ r) > Ps.

Fig. 6 is a diagram illustrating a relationship between the pressure measurement value Pr and the predicted pressure Pp, and shows a case where Pe (θ r) < Ps.

Fig. 7 is a graph showing the determination condition by the pilot pressure Pp in the case of "excess" and "completely excess", and the opening degree relationship and the pressure relationship at that time.

Fig. 8 is a diagram showing an example of the relationship between the opening degree θ and the effective exhaust speed Se.

Fig. 9 is a diagram showing changes in the pressure (the pressure measurement value Pr and the pilot pressure Pp), the index signal β, and the opening degree setting θ 1 when the opening degree setting θ 1 is fixed to the value θ 1_ fix.

Fig. 10 is a diagram showing the determination conditions using the index signal β in the case of "over" and "completely over", and the opening degree relationship and the pressure relationship at that time.

Fig. 11 is a flowchart showing an example of the control process in the case where the pilot pressure Pp and the indicator signal β are used in combination.

Fig. 12 is a diagram showing transition of the pressure measurement value Pr, the index signal β, the opening setting θ 1, and the opening setting θ 2 in the rise case (up case).

Fig. 13 is a diagram showing a comparative example.

Fig. 14 is a flowchart for explaining modification 1.

Fig. 15 is a diagram illustrating a rising case in modification 1.

Fig. 16 is a flowchart for explaining modification 2.

Fig. 17 is a flowchart for explaining modification 3.

[ description of symbols ]

1: valve body

2: valve control device

3: vacuum chamber

4: vacuum pump

12: valve body

13: motor with a stator having a stator core

21: voltage regulation controller

22: motor drive unit

23: storage unit

210: estimation calculation unit

220: feedforward controller

230: feedback controller

Pp: preliminary pressure measurement

Pr: pressure measurement

Ps: target pressure value

θ 1, θ 2, θ set: opening degree setting

θ r: measured value of opening degree

θ se: target opening degree estimate value

β, β 1, β 2: index signal

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing a schematic configuration of a vacuum valve attached to a vacuum processing apparatus. The vacuum valve includes a valve body 1 provided with a valve body 12, and a valve control device 2 for controlling the driving of the valve body. The valve body 1 is installed between the vacuum chamber 3 and the vacuum pump 4. In the vacuum chamber 3, a gas such as a process gas is introduced through a flow rate controller 32. The flow rate controller 32 is a device for controlling the flow rate Qin of the gas introduced into the vacuum chamber 3, and is controlled by a main controller (not shown) of a vacuum processing apparatus provided with the vacuum chamber 3. The pressure in the vacuum chamber 3 (chamber pressure) is measured by a vacuum gauge 31, and a pressure measurement value Pr thereof is inputted to the valve control device 2.

The valve body 1 is provided with a motor 13 for driving the valve element 12 to open and close. The valve body 12 is driven to open and close by a motor 13. The motor 13 is provided with an encoder (encoder)130 for detecting an opening/closing angle of the valve body 12. The detection signal of the encoder 130 is input to the valve control device 2 as an opening degree signal θ r of the valve body 12 (hereinafter referred to as an opening degree measurement value θ r).

The valve control device 2 that controls the valve main body 1 includes a pressure regulating controller 21, a motor drive unit 22, and a storage unit 23. The valve control device 2 receives the pressure measurement value Pr and the opening measurement value θ r, and also receives a pressure target value Ps of the vacuum chamber 3 from the main controller of the vacuum processing apparatus. The storage unit 23 stores parameters necessary for controlling the valves (e.g., data relating to an effective exhaust rate Se, a plant gain Gp, and the like, which will be described later). The motor drive unit 22 includes an inverter circuit for driving the motor and a motor control unit for controlling the inverter circuit, and receives an opening degree measurement value θ r from the encoder 130. The chamber pressure Pr measured by the vacuum gauge 31 is input to the pressure-regulating controller 21, and the target pressure Ps of the vacuum chamber 3 is input from the main controller of the vacuum processing apparatus described above.

The valve control device 2 includes an arithmetic Processing device such as a microcomputer (micro computer) including, for example, a Central Processing Unit (CPU), a Memory (Read Only Memory (ROM), Random Access Memory (RAM)), a peripheral circuit, and the like, and functions of the pressure regulating controller 21 and the motor control Unit of the motor drive Unit 22 are realized by a software program (software program) stored in the ROM. The storage unit 23 includes a memory of a microcomputer. In addition, a digital arithmetic unit such as a Field Programmable Gate Array (FPGA) and peripheral circuits thereof may be included.

Fig. 2 is a functional block diagram of the valve body 1 and the valve control device 2. The voltage regulation controller 21 includes an estimation operation unit 210, a feed-forward controller (feed-forward controller)220, and a feedback controller (feedback controller) 230. The opening degree measurement value θ r detected by the encoder 130 is input to the motor drive unit 22 and the estimation calculation unit 210.

In the present embodiment, as in the invention of patent document 1 described above, the pressure target value is approximated by performing coarse adjustment to be close to the pressure target value by open control, and further switching to closed control, and fine adjustment. In the pressure regulating controller 21, the estimation arithmetic unit 210 and the feedforward controller 220 correspond to an open control unit, and the subtractor and the feedback controller 230 that generate the deviation ∈ (═ Pr-Ps) correspond to a closed control unit.

The pressure measurement value Pr, the pressure target value Ps, and the opening degree measurement value θ r are input to the estimation calculation unit 210 of the opening control unit. The estimation calculation unit 210 calculates a target opening degree estimation value θ se, a predicted pressure Pp, and an index signal β indicating a tendency of change in the pressure measurement value Pr, based on the pressure measurement value Pr, the pressure target value Ps, and the opening degree measurement value θ r. Generally, even if the valve opening degree is fixed to a certain value, it takes a certain time until the chamber pressure reaches a pressure equilibrium value corresponding to the valve opening degree. The predicted pressure Pp is an estimated pressure value after t seconds from the time point at which the pressure measurement value Pr is measured. Further, the method of estimating the preliminary pressure Pp is described in detail in japanese patent laid-open No. 2018-106718, and the description thereof is omitted here. In addition, the calculation method of the target opening degree estimation value θ se and the index signal β will be described below.

The feedforward controller 220 of the opening control unit outputs the opening setting θ 1 based on the target opening estimation value θ se and the index signal β. Further, the feedback controller 230 of the closed control unit outputs the opening degree setting θ 2 based on the deviation ∈ Pr — Ps. The output opening degree setting θ 1 and the opening degree setting θ 2 are added, and the addition result is input to the motor drive unit 22 as an opening degree setting θ set. The motor drive unit 22 drives the motor 13 based on the opening degree setting θ set and the opening degree measurement value θ r input from the encoder 130.

As will be described later, in the present embodiment, the determination using the pilot pressure Pp in the opening control and the determination using the index signal β related to the pressure balance value when the opening degree setting θ 1 is fixed are used in combination. The determination using the pilot voltage Pp is performed according to the voltage regulation logic shown in fig. 3. Hereinafter, the voltage regulation logic using the pilot voltage Pp of fig. 3 will be described, and then a method of setting the indicator signal β and a method of determining the indicator signal β will be described.

The coordinate system shown in fig. 3 is a coordinate system θ -P having the points (θ se, Ps) as the origin. The target opening degree estimation value θ se is an opening degree of the valve body 12 when the calculated pressure target value Ps is estimated. In such a coordinate system θ -P, which of the opening θ and the closing direction is controlled is determined based on which of the first quadrant to the fourth quadrant the point (θ r, Pr) is located, and the magnitude relation between the pilot pressure Pp and the pressure target value Ps.

When the points (θ r, Pr) before the change of the opening degree are located in the second quadrant and the fourth quadrant, the opening degree θ is adjusted in the direction of the opening degree target estimation value θ se. As a result, the pressure measurement value Pr changes in the direction of the pressure target value Ps. That is, the pressure decreases in the case of the second quadrant, and increases in the case of the fourth quadrant. The starting point of the control start is either the second quadrant or the fourth quadrant, and the fourth quadrant is the case of a rising case where the pressure rises from the pressure Pstt at the starting point, and the second quadrant is the case of a falling case (down case) where the pressure falls from the pressure Pstt at the starting point.

On the other hand, when the points (θ r, Pr) before the change of the opening degree are located in the first quadrant and the third quadrant, the direction of the opening degree adjustment is set according to the magnitude relationship between the pilot pressure Pp and the pressure target value Ps. In the first quadrant, when the pilot pressure Pp is greater than the pressure target value Ps as Pp > Ps, the opening degree is adjusted in a direction to increase the opening degree (a direction indicated by a rightward arrow), or the opening degree value is maintained as it is as shown by a circle 50. Conversely, in the case of Pp Ps, the opening degree is adjusted in a direction to decrease the opening degree (a direction indicated by a leftward arrow). In the third quadrant, when Pp > Ps, the opening degree is adjusted in a direction to increase the opening degree (a direction indicated by a rightward arrow). Conversely, in the case of Pp Ps, the opening degree is adjusted in a direction to decrease the opening degree (in a direction indicated by a leftward arrow), or the opening degree value is maintained as it is as indicated by a circle 50.

Fig. 4 shows an example of the trajectory of the points (θ r, Pr) obtained by the open control when the coordinates (θ r, Pr) of the start point at which the control is started are located in the fourth quadrant like the point a1 and the point B1. In the example where the starting point is the point a1, the opening degree is changed by the opening control, and the starting point moves to the point a2 near the target opening degree estimation value θ se. When the pressure measurement value Pr is close to the target opening degree estimation value θ se, the closing control is performed.

In the example where the starting point is the point B1, the start point moves to the point B2 in the third quadrant by the opening degree change by the opening control. Here, the predicted pressure Pp estimated and calculated when the valve body 12 moves to the point B2 is Pp Ps, and the opening degree of the valve body 12 is maintained at the opening degree at the position of the point B2. While the opening degree is maintained, the pressure measurement value Pr and the estimated pressure Pp calculated by estimation continue to increase, and the position of the point (θ r, Pr) moves upward. Then, at the time point when the pressure reaches the point B3, the predicted pressure Pp becomes Pp > Ps, and the opening degree is changed in the increasing direction. As a result, the opening degree is changed to move to a point B4 near the target opening degree estimation value θ se. When the pressure measurement value Pr is close to the target opening degree estimation value θ se, the closing control is performed.

When the opening degree measured value θ r finally becomes the target opening degree estimated value θ se by the opening control, the opening degree setting θ 1 output from the feedforward controller 220 in fig. 2 is switched from the opening control to the closing control in a state where the value is fixed, and when the value is switched to the closing control, the pressure target value Ps is input to the subtraction point in fig. 2, and the feedback controller 230 outputs the opening degree setting θ 2 based on the deviation ∈ Pr-Ps. Typically, the feedback controller 230 includes a Proportional gain, an Integral gain (so-called Proportional Integral (PI) gain). The motor drive unit 22 controls the opening degree based on the opening degree setting θ set equal to θ 1 (fixed) + θ 2. As long as the valve body 12 does not operate at high speed, the opening degree measurement value θ r becomes θ r ═ θ 1+ θ 2.

Before the closing control is started, the pressure measurement value Pr is input to the subtraction point instead of the pressure target value Ps. Therefore, the opening degree setting θ 2 is output from the feedback controller 230 as 0 while the pressure deviation ∈ is input to the feedback controller 230 as 0 during the opening control.

As described above, the predicted pressure Pp in the logic of fig. 3 is an estimated value of the chamber pressure after t seconds have elapsed from the present time (for example, a time longer than the control period such as 0.4 seconds). In the control example of B1 → B2 → B3 → B4 shown in fig. 4, the predicted pressure Pp exceeds the pressure target value Ps (that is, Pp > Ps) at the time point of B3, and the valve opening degree is changed in the direction of the target opening degree estimated value θ se and moves to the point B4.

Fig. 5 is a graph showing a relationship between the pressure measurement value Pr and the predicted pressure Pp, in which the horizontal axis represents time and the vertical axis represents pressure. Lines L1 and L2 show the time transition of the pressure measurement value Pr and the pilot pressure Pp when the valve body opening is fixed to the opening measurement value θ r at the point B2. The predicted pressure Pp is a predicted pressure after t seconds from the time point of measuring the pressure measurement value Pr, and thus the line L2 is shifted more upward than the line L1 of the pressure measurement value Pr. At the time point of the point B2, the predicted pressure Pp becomes Pp < Ps with respect to the pressure target value Ps.

However, when the pressure measurement value Pr increases in the pressure direction of the equilibrium state with the passage of time, the predicted pressure Pp also increases accordingly, and the predicted pressure Pp exceeds the pressure target value Ps at the time point of the point B3. When a sufficient time further elapses, the pressure measurement value Pr converges to a pressure equilibrium value (pressure value in equilibrium state) Pe (θ r) at the time of the opening measurement value θ r. In the equilibrium state, the predicted pressure Pp also converges to Pe (θ r).

Accordingly, the opening degree measurement value θ r is smaller than the opening degree corresponding to the pressure target value Ps, and readjustment is necessary in a direction to increase the opening degree of the valve body. By using the pilot pressure Pp, it can be determined that readjustment is necessary at a time point before the actual pressure measurement value Pr exceeds the pressure target value Ps, that is, at a timing B3 at which the pilot pressure Pp becomes Pp > Ps.

On the other hand, in the control example a1 → a2 shown in fig. 4, the pilot pressure Pp does not exceed the pressure target value Ps. At this time, it is unclear at which time point the predicted pressure Pp does not exceed the pressure target value Ps. For example, at the time point when the pressure increase rate of the pilot pressure Pp becomes almost zero, it can be determined that the pilot pressure Pp does not exceed the pressure target value Ps, but it takes a long time to recognize that the pressure increase rate becomes almost zero. Therefore, the voltage regulation time is unnecessarily long. In the control example a1 → a2, the calculation error of the target opening degree estimate value θ se is small. However, the target opening degree estimation value θ se is often calculated with a large error, and as a result, the target opening degree estimation value θ se is often deviated in a direction larger than the true target opening degree θ s. In particular, it is known that the difference between the gas species (molecular weight) and the gas flow rate is large.

In general, when the target opening degree estimation value θ se is inevitably calculated with an error and deviates in a direction larger than the true target opening degree θ s with respect to the pressure target value Ps, as shown in fig. 6, the pressure equilibrium value (equilibrium pressure value) Pe (θ r) of the pressure measurement value Pr becomes Pe (θ r) < Ps. At this time, the pressure balance value Pe (θ r) is shifted downward in the drawing with respect to the pressure target value Ps, and the pilot pressure Pp does not exceed the pressure target value Ps at all.

Fig. 4 shows a case where the target pressure value Ps is higher than the pressure Pstt at the time of starting the pressure regulation, but in a case where the target pressure value Ps is lower than the pressure Pstt at the time of starting the pressure regulation, the pilot pressure Pp may exceed the target pressure value Ps or may not exceed the target pressure value Ps at all. In the case of the drop case, Ps < Pstt, so that "exceeding" the pre-pressure Pp by the pressure target value Ps means that Pp < Ps, and "completely not exceeding" means that Pp > Ps. Further, when the predicted pressure Pp does not exceed the pressure target value Ps at all, the determination that the predicted pressure Pp does not exceed the pressure target value Ps at all becomes ambiguous as described above, and the pressure adjustment time becomes unnecessarily long.

When the determination conditions using the pilot pressure Pp in the above "exceeding" and "completely not exceeding" are summarized, the opening degree relationship and the pressure relationship at that time are as shown in fig. 7. The opening degree θ 1_1 in fig. 7 is a pressure balance value when the opening degree setting θ 1 is set at the timing of prediction determination during the control period, and Pe (θ 1_1) is the opening degree θ 1_ 1. The prediction determination timing is set to a timing at which the opening θ is fixed to a fixed value. The target opening degree estimate value θ se is described on the assumption that it has an error from the true target opening degree θ s.

In the case of the rising case (Pstt < Pr), in a situation where the predicted pressure Pp "exceeds the pressure target value Ps (Pp > Ps)," the point (θ r ═ θ 1_1, Pr) is located in the third quadrant as shown by the point B2 in fig. 4, and the opening θ 1_1 set as θ 1_1 θ se becomes θ 1_1 < θ s. That is, θ 1_1 θ se < θ s, and the pressure relationship is Pstt < Pr < Ps < Pe (θ se) Pe (θ 1_ 1).

In the rising case (Pstt < Pr), in a situation where the predicted pressure Pp "does not exceed the pressure target value Ps at all (Pp < Ps)", the points (θ r ═ θ 1_1, Pr) are located in the fourth quadrant as shown by the point a2 in fig. 4, and are located in the fourth quadrant as shown by θ 1_1

The opening degree θ 1_1 set as θ se is θ 1_1 > θ s. That is, θ 1_1 θ se > θ s, and the pressure relationship is Pstt < Pr < Pe (θ 1_1) Pe (θ se) < Ps.

In the case of the decrease (Pstt > Pr), the opening degree θ 1_1 set as θ 1_1 θ se becomes θ 1_1 > θ s in a situation where the predicted pressure Pp "exceeds the (Pp < Ps)" pressure target value Ps. That is, θ 1_1 θ se > θ s, and the pressure relationship is Pe (θ 1_1) Pe (θ se) < Ps < Pr < Pstt.

In the case of the decrease (Pstt > Pr), the opening θ 1_1 set as θ 1_1 θ se is θ 1_1 < θ s in a situation where the predicted pressure Pp "does not exceed the pressure target value Ps at all (Pp > Ps)". I.e., is θ 1_1

θ se < θ s, and the pressure relationship is Ps < Pe (θ se) Pe (θ 1_1) < Pr < Pstt.

(introduction of index Signal. beta.)

In the present embodiment, the index signal β is defined by the following formula (1). The pressure measurement value Pr of the vacuum chamber 3 is satisfied by an exhaust formula expressed by the following formula (2), and the molecule (dPr/dt) of the index signal β is an amount based on the exhaust formula.

β＝(dPr/dt)/(Ps-Pr)···(1)

V×(dPr/dt)+Se×Pr＝Qin···(2)

In the formula (2), the right Qin represents the flow rate of the gas introduced into the vacuum chamber 3. On the left side of the equation (2), V is the volume of the vacuum chamber 3, dPr/dt is the time derivative of the pressure measurement Pr, and Se is the effective evacuation rate of the vacuum evacuation system associated with evacuation of the vacuum chamber 3. The effective exhaust gas velocity Se is an amount determined by the following factors: a conductance (conductance) determined by the chamber structure and the opening θ r of the valve body 12, and an exhaust speed of the vacuum pump 4. The relationship between the opening degree θ of the valve element 12 and the effective exhaust speed Se generally has a monotonically increasing relationship as shown in fig. 8.

Normally, when the vacuum valve is attached to the vacuum chamber 3 and used, an initial calibration operation relating to the effective exhaust speed Se, that is, an initial calibration operation relating to valve body control is performed. In general, gain correction of the controller is performed in accordance with the volume of the vacuum chamber 3, the sensitivity of the valve body, and the like, in a state where a representative gas or an average gas condition (gas type, gas flow rate) of the process condition to be applied is set. As the averaging condition, for example, the average molecular weight of the mixed gas is often determined and replaced by a gas type which is relatively easy to handle.

The semiconductor process in the vacuum chamber 3 equipped with the vacuum valve includes a plurality of pressure regulation events in which various conditions of the type of gas introduced into the vacuum chamber 3, the gas flow rate Qin, and the target pressure value Ps are changed at predetermined time intervals. In each pressure regulation event, immediately after the start, the flow rate of the gas is converged to a predetermined flow rate value by the flow rate controller 32 (see fig. 1), and the chamber pressure (pressure measurement value Pr) is converged to the pressure target value Ps by adjusting the valve opening degree to control the effective exhaust velocity Se.

Generally, the timing of convergence completion of flow control by the flow controller 32 is earlier than the timing of convergence completion of pressure control by the vacuum valve. Further, in the prediction determination timing at the time of the open control in the present embodiment, it is also conceivable that the flow rate value is almost converged. That is, the gas flow rate Qin converges to a constant flow rate Qin0, and Qin is assumed to be constant Qin 0.

The prediction determination timing is set to a timing at which the opening degree is fixed, and the opening degree at the fixed timing is represented as θ 1_ fix. Hereinafter, the effective exhaust speed Se (θ 1_ fix) corresponding to the opening θ 1_ fix is represented as Se _ fix, and the effective exhaust speed Se (θ s) corresponding to the opening θ s at the pressure target value Ps is represented as Se 0. In this case, the flow rate value Qin0 is expressed by the following expression (3). Pe (θ 1_ fix) is a pressure balance value at the opening θ 1_ fix.

Qin0＝Se0×Ps＝Se_fix×Pe(θ1_fix)···(3)

According to the equation (3), the pressure equilibrium value Pe (θ 1_ fix) is represented by the following equation (4). The expression of the exhaust gas when the opening degree is fixed to θ 1_ fix is expressed by the following expression (5).

Pe(θ1_fix)＝(Se0/Se_fix)×Ps···(4)

V×(dPr/dt)+Se_fix×Pr＝Qin0···(5)

The numerator and denominator of the formula (1) for providing the index signal β described above can be modified according to the formulas (4) and (5) as shown in the following formulas (6) and (7).

Molecule ═ dPr/dt)

＝(Se0×Ps-Se_fix×Pr)/V

＝(Se_fix/V)×{(Se0/Se_fix)×Ps-Pr}···(6)

Denominator (Ps-Pr)

＝{(Se0/Se_fix)×Ps-Pr}-{(Se0/Se_fix)×Ps-Ps}···(7)

Therefore, the index signal β is expressed as the following expression (8). In the formula (8), only the pressure measurement value Pr is a time-varying amount, and varies with time as Pr → Ps. The other amounts are constant amounts (constant values) with time.

β＝(Se_fix/V)/[1-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pr}]···(8)

(method of determining Using index Signal. beta.)

Hereinafter, the determination method for the four cases shown in fig. 7 will be described using the index signal β provided by equation (8). Here, if the relationship between the applied opening degree θ and the effective exhaust gas speed Se is a monotonically increasing relationship as shown in fig. 8, for example, if θ 1_ fix > θ s, Se _ fix > Se0 can be said. In the following description, the relationship of fig. 8 is applied. First, a case of "completely not exceeding" which is a problem in the case of using the pilot pressure Pp will be described, and then a case of "exceeding" will be described.

[1. case of "completely not exceeding" in the ascending case ]

The pressure measurement value Pr during the pressure rise satisfies the relationship of Pstt < Pr < Pe (θ 1 — 1) Pe (θ se) < Ps, as described in FIG. 7. As described above, θ 1_1 is collectively expressed as θ 1_ fix, and thus the relationship of the following expression (9) can be obtained from the relationship of Pr < Pe (θ 1_ fix) < Ps and expression (4).

Pr＜(Se0/Se_fix)×Ps＜Ps···(9)

When f (pr) of the following formula (10) is used, the right denominator of the formula (8) is 1+ f (pr).

F(Pr)＝-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pr}···(10)

From the formula (9), it is found that { (Se0/Se _ fix). times.Ps-Ps } < 0, { (Se0/Se _ fix). times.Ps-Pr } > 0 holds, and F (Pr) > 0. Therefore, f (Pr) (i.e., the right denominator of equation (8)) becomes a positive value, and even if the pressure measurement value Pr changes with time, the index signal β ═ is always positive (dPr/dt)/(Ps-Pr).

In the case of a rising case where the pressure Pstt rises from the start point of control start, the pressure measurement value Pr is Pr > Pstt, and therefore, the following formula (11) is satisfied in accordance with the relationship of { (Se0/Se _ fix) × Ps-Pstt } > { (Se0/Se _ fix) × Ps-Pr } > 0.

{(Se0/Se_fix)×Ps-Pr}/{(Se0/Se_fix)×Ps-Pstt}＜1···(11)

The magnitude relationship between the formula obtained by multiplying f (pr) of formula (10) by the left side of formula (11) and f (pr) is as shown in formula (12) below.

F(Pr)＞-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}···(12)

The right denominator of equation (8) is 1+ f (pr) and is positive, so equation (13) holds.

(Right denominator) > 1- { (Se0/Se _ fix). times.Ps-Ps }/{ (Se0/Se _ fix). times.Ps-Pstt } 1/(right denominator) < 1/[1- { (Se0/Se _ fix). times.Ps-Ps }/{ (Se0/Se _ fix). times.Ps-Pstt } ] · (13)

Since (Se _ fix/V) of the equation (8) is a positive value, the index signal β satisfies the following equation (14) in accordance with the relationship of the equation (13).

β＜(Se_fix/V)/[1-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}]···(14)

In the rising case, the pressure measurement value Pr in the formula (8) of the index signal β rises from the pressure Pstt at the starting point. As described above, f (Pr) contained in the right denominator 1+ f (Pr) of formula (8) is a positive value, and the smaller Pr is, the smaller f (Pr) is. Therefore, the right denominator of equation (8) is 1+ f (Pr) and becomes smaller as Pr becomes smaller, and the index signal β represented by equation (8) becomes maximum at the pressure Pstt at the start of the rise of the pressure measurement value Pr. As can be seen from equation (14), the smaller the value of the index signal β when Pr is Pstt (i.e., the maximum value of the index signal β) is, the larger the value becomes, and the upper limit value of the index signal β is set to Se0/V when Pstt is 0 on the right side of equation (14).

On the other hand, when the pressure measurement value Pr rises from the pressure Pstt at the starting point and reaches almost (Se0/Se _ fix) × Ps, f (Pr) represented by the formula (10) becomes f (Pr) → + ∞. If f (pr) is used, the index signal β is represented by β ═ (Se _ fix/V)/[1+ f (pr) ], and therefore the index signal β converges to +0 as β → + 0. As described above, when "does not exceed at all" in the case of rising, it is known that the index signal β monotonically decreases toward a zero value with Se0/V as an upper limit.

Fig. 9 is a diagram showing changes in the pressure (the pressure measurement value Pr and the pilot pressure Pp), the index signal β, and the opening degree setting θ 1 when the opening degree setting θ 1 is fixed to the value θ 1_ fix. After the opening degree setting θ 1 is fixed to θ 1_ fix, the pressure measurement value Pr and the predicted pressure Pp continue to increase, and both converge to the pressure balance value Pe (θ 1_ fix) at the opening degree θ 1_ fix if the pressure measurement value Pr and the predicted pressure Pp continue to increase for a sufficiently long time. The calculated index signal β monotonically decreases toward a zero value with Se0/V as an upper limit. Therefore, the detection index signal β monotonically decreases, and it can be determined that the opening degree setting θ 1 — θ 1_ fix is "completely out of the way".

[2. case of completely not exceeding in the case of descent ]

Next, a case of "not to exceed at all" in the lowering case, that is, a response process of the pressure measurement value Pr from the pressure Pstt of the starting point to (Se0/Se _ fix) × Ps was investigated. As will be described below, it is understood that, at this time, too, the value monotonically decreases toward zero with (Se _ fix/V) as an upper limit, as in the case of "not exceeding at all" in the rising case.

The pressure measurement value Pr in the pressure drop satisfies the relationship Ps < Pe (theta 1_1) Pe (theta se) < Pr < Pstt. As described above, θ 1_1 is collectively expressed as θ 1_ fix, and thus the relationship of the following formula (15) can be obtained from Ps < Pe (θ 1_1) < Pr of the relationship of the pressures and Pe (θ 1_ fix) ═ Se0/Se _ fix) × Ps of the formula (4).

Ps＜(Se0/Se_fix)×Ps＜Pr···(15)

According to the formula (15), { (Se0/Se _ fix). times.Ps-Pr } < 0, { (Se0/Se _ fix). times.Ps-Ps } > 0, F (Pr) represented by the formula (10) becomes F (Pr) > 0. Therefore, the right denominator of equation (8) becomes a positive value, and the indicator signal β always becomes a positive value even if the pressure measurement value Pr changes with time.

In the case of a decreasing case where the pressure Pstt decreases from the starting point of the control, the pressure measurement value Pr is Pr < Pstt, and thus the above equation (11) is similarly established in accordance with the relationship of- { (Se0/Se _ fix) × Ps-Pstt } > - { (Se0/Se _ fix) × Ps-Pr } > 0.

{(Se0/Se_fix)×Ps-Pr}/{(Se0/Se_fix)×Ps-Pstt}＜1···(11)

The above equation (12) holds similarly for the magnitude relationship between f (pr) and the equation obtained by multiplying f (pr) of equation (10) by the left side of equation (11).

F(Pr)＞-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}···(12)

Therefore, as in the case of "not to exceed at all" in the above-described rising case, the expressions (13) and (14) are satisfied.

1/(right denominator) < 1/[1- { (Se0/Se _ fix). times.Ps-Ps }/{ (Se0/Se _ fix). times.Ps-Pstt } ] · (13)

β＜(Se_fix/V)/[1-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}]···(14)

In the case of the fall, the pressure measurement value Pr in the formula (8) of the index signal β falls from the pressure Pstt at the starting point to (Se0/Se _ fix) × Ps (> Ps) corresponding to the opening θ 1_ fix. In the descending case, { (Se0/Se _ fix). times.Ps-Pr } of formula (8) is negative, and the absolute value thereof becomes smaller as the pressure measurement value Pr becomes closer to (Se0/Se _ fix). times.Ps. That is, the denominator on the right side of equation (8) is that the pressure measurement value Pr becomes larger as it approaches (Se0/Se _ fix) × Ps, and conversely, the index signal β becomes smaller. In other words, the indicator signal β reaches a maximum at the pressure Pstt at the beginning of the fall of the pressure measurement value Pr. Therefore, also in the case of the descending case, the value Se0/V when Pstt is 0 on the right side of equation (14) becomes the upper limit value of the index signal β.

On the other hand, the pressure measurement value Pr starts to decrease from the pressure Pstt at the starting point, and when it almost reaches (Se0/Se _ fix) × Ps, f (Pr) represented by the formula (10) becomes f (Pr) → + ∞. If f (pr) is used, the index signal β is represented by β ═ (Se _ fix/V)/[1+ f (pr) ], and therefore the index signal β converges to +0 as β → + 0. As a result, even in the case of "not exceeding at all" in the case of the drop, the index signal β monotonically decreases toward zero with Se0/V as an upper limit.

[3. case of "over" in ascending case ]

In the case of "over" in the rising case, as shown in fig. 7, the relationship of Pstt < Pr < Ps < Pe (θ se) Pe (θ 1 — 1) is satisfied. Since Pr < Ps < Pe (θ 1_1), when Pe (θ 1_1) ═ Pe (θ 1_ fix) ═ Pe (Se0/Se _ fix) × Ps is considered, in formula (8), { (Se0/Se _ fix) × Ps-Pr } > 0, and { (Se0/Se _ fix) × Ps-Ps } > 0. Since Pr < Ps, the following formula (16) holds.

0＜{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pr}＝-F(Pr)＜1···(16)

In the right-side magnitude relation of equation (16), the denominator on the right side in equation (8) is 1+ f (pr) and the index signal β always becomes a positive value. In the case of the ascending case, as described above, equation (11) holds.

{(Se0/Se_fix)×Ps-Pr}/{(Se0/Se_fix)×Ps-Pstt}＜1···(11)

When f (pr), which is a negative value, is multiplied to both sides of equation (11), equation (17) below is obtained.

-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}＞F(Pr)···(17)

The formula (17) is modified as shown in the formula (18).

1-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}＞1+F(Pr)

1/[1-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}]＜1/{1+F(Pr)}···(18)

If (Se _ fix/V) which is a positive value is multiplied to both sides of equation (18), equation (19) below can be obtained.

(Se_fix/V)/[1-{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pstt}]＜β···(19)

In the rising case, the pressure measurement value Pr in the formula (8) of the index signal β rises from the pressure Pstt at the starting point. The value of { (Se0/Se _ fix). times.Ps }/{ (Se0/Se _ fix). times.Ps-Pr } of the right denominator of formula (8) is 0 to 1 as in formula (16), and the smaller Pr, that is, the farther Pr is from (Se0/Se _ fix). times.Ps, the smaller value. Therefore, the smaller Pr, the larger the right denominator of equation (8), and conversely, the smaller the index signal β. Therefore, the index signal β reaches the minimum at the pressure Pstt at the start of the rise of the pressure measurement value Pr. As can be seen from equation (19), the value of the index signal β (i.e., the minimum value of the index signal β) when Pr is Pstt becomes smaller, and the value Se0/V when Pstt is 0 on the right side of equation (19) becomes the lower limit value of the index signal β.

Further, since the pressure measurement value Pr starts increasing from the pressure Pstt at the start point and almost reaches Ps, the right denominator of equation (8) is a positive value and close to zero as (right denominator) → +0, and thus the index signal β becomes β → + ∞atthis time. That is, in the case of "over" in the case of the rising, the index signal β monotonically increases with Se0/V as the lower limit.

[4. case of "over" in case of descent ]

In the case of "over" in the falling case, as shown in fig. 7, the relationship of Pe (θ 1_1) Pe (θ se) < Ps < Pr < Pstt is satisfied. Since Pe (θ 1_1) < Ps < Pr, in formula (8), { (Se0/Se _ fix). times.Ps-Pr } < 0, { (Se0/Se _ fix). times.Ps-Ps } < 0. Since Ps < Pr, the above equation (16) holds, the right denominator of equation (8) becomes a positive value, and the index signal β always becomes a positive value.

0＜{(Se0/Se_fix)×Ps-Ps}/{(Se0/Se_fix)×Ps-Pr}＝-F(Pr)＜1···(16)

In the case of "over" in the case of the descent, the expression (11) is satisfied in the same manner as in the case of "completely over" in the case of the descent.

{(Se0/Se_fix)×Ps-Pr}/{(Se0/Se_fix)×Ps-Pstt}＜1···(11)

With respect to equation (11), equations (17) to (19) can be obtained as in the case of "over" in the rising case.

In the case of a drop, the pressure measurement Pr in equation (8) of the indicator signal β drops from the starting pressure Pstt. The value of { (Se0/Se _ fix). times.Ps }/{ (Se0/Se _ fix). times.Ps-Pr } of the right denominator of formula (8) is 0 to 1 as shown in formula (16), and the smaller Pr, that is, the closer Pr is to (Se0/Se _ fix). times.Ps, the larger value. Therefore, the right denominator of equation (8) becomes smaller as Pr becomes closer to (Se0/Se _ fix) × Ps, whereas the index signal β becomes larger. Therefore, the index signal β is smallest when the pressure measurement value Pr is the pressure Pstt farthest from (Se0/Se _ fix) × Ps. As can be seen from equation (19), the value of the index signal β (i.e., the minimum value of the index signal β) when Pr is Pstt becomes smaller, and the value Se0/V when Pstt is 0 on the right side of equation (19) becomes the lower limit value of the index signal β.

Further, since the pressure measurement value Pr starts decreasing from the pressure Pstt at the start point and almost reaches Ps, the right denominator of equation (8) is a positive value and close to zero as (right denominator) → +0, and thus the index signal β becomes β → + ∞atthis time. That is, in the case of "over" in the case of the fall, it is known that the index signal β monotonically increases with Se0/V as the lower limit.

The results of the case of "exceeding" and the case of "completely not exceeding" in the above-described ascending case and descending case are summarized as shown in fig. 10.

(timing of generating index Signal. beta.)

An example of the generation timing of the indicator signal β by the estimation calculation unit 210 of fig. 2 will be described. The target pressure value Ps, the measured pressure value Pr, and the opening degree measured value θ r are input to the estimation calculation unit 210. The estimation calculation unit 210 calculates Δ Pr/Δ t from the difference Δ Pr of the pressure measurement values Pr between appropriate control cycles Δ t (e.g., 10ms), thereby obtains a pressure differential (dPr/dt) of equation (1), and calculates the indicator signal β based on the pressure differential and the input pressure target value Ps and pressure measurement value Pr.

In this way, the index signal β does not use parameters other than the pressure target value Ps and the pressure measurement value Pr, and therefore can be applied even if the gas type and the gas flow rate of the gas introduced into the vacuum chamber 3 are unknown. In other words, even if the gas type and the gas flow rate are unknown, the index signal β with high reliability can be obtained.

As the generation timing of the index signal β, it is sufficient to determine whether the index signal β monotonically increases or monotonically decreases with time in a state where the opening degree setting θ 1 of the opening control is fixed, that is, in a state of θ 1_ fix. For example, when the control cycle is 10ms, the index signal β is calculated a plurality of times every 10ms so as to be calculated 10 to 40 times in a period of 100 to 400 ms. Then, if a tendency to increase continuously (previous value < present value) is seen for the index signal β calculated a plurality of times, it is determined as "over", and if a tendency to decrease continuously (previous value > present value) is seen, it is determined as "not over at all".

(control process based on pilot pressure Pp and indicator signal beta)

Fig. 11 is a flowchart showing an example of control processing performed by the pressure regulating controller 21 when the pilot pressure Pp and the indicator signal β are used in combination. Fig. 11 shows a determination process using the pilot pressure Pp and the index signal β, and an opening degree control process after the determination. Fig. 12 is a diagram showing transition of the pressure measurement value Pr, the index signal β, and the opening degree setting θ 1 in the rising case. In the determination described below using both the predicted pressure Pp and the index signal β, the "excess" is determined by the predicted pressure Pp, and the "completely no excess" is determined by the index signal β.

When the pressure target value Ps is input to the pressure regulation controller 21, the estimation calculation unit 210 calculates a target opening degree estimation value θ se based on the pressure target value Ps, and outputs an opening degree setting θ 1_ fix from the feedforward controller 220 based on the target opening degree estimation value θ se. The opening degree setting θ 1_ fix is input to the motor drive unit 22, and the valve body 12 is driven so that the valve body opening degree becomes the value of the opening degree setting θ 1_ fix.

In step S10 of fig. 11, it is determined whether or not the opening degree measurement value θ r is equal to the opening degree setting θ 1_ fix output from the feedforward controller 220. If it is determined in step S10 that θ r is θ 1_ fix, the process proceeds to step S20. In step S20, the estimation calculation unit 210 calculates the index signal β. In step S30, m, which indicates the number of times β (previous) > β (present) is determined in step S70 to be described later, is set to 0.

In step S40, the predicted pressure Pp is calculated. In step S50, it is determined whether or not the predicted pressure Pp exceeds the pressure target value Ps. If Pp > Ps is determined, the process proceeds to step S100, and an opening degree change process is executed. The opening degree change process of step S100 will be described below. On the other hand, if Pp > Ps is determined not, the process proceeds to step S60. In step S60, the index signal β is calculated.

In step S70, it is determined whether the predicted pressure Pp "does not exceed" the pressure target value Ps at all. Specifically, the index signal β (previous time) calculated in step S20 is compared with the index signal β (current time) calculated in step S60, and it is determined whether or not β (previous time) > β (current time). As shown in fig. 10, in both the case of the rising case and the case of the falling case, when "does not exceed at all", the index signal β monotonically decreases, and the index signal β satisfies the determination condition "β (previous) > β (present)". If it is determined in step S70 that β (previous) > β (current), the routine proceeds to step S80, and if it is determined that β (previous) > β (current), the routine returns to step S30.

For example, in the case of the ascending case shown in fig. 12, the index signal β (previous time) and the index signal β (present time) are calculated during a predetermined period including time t1 in a state fixed to θ 1 — θ se (θ 1 — fix). The calculated index signal beta (last time) and the index signal beta (this time) satisfy beta (last time) > beta (this time). Therefore, the determination in step S70 is yes (yes), and the process proceeds to step S80.

In step S80, the value of m is increased by + 1. In step S90, it is determined whether or not the number m of times β (previous) > β (present) has reached the upper limit N, and if it has reached (m equals N), the routine proceeds to step S100. If not (m < N), the process returns to step S40, and the process from step S40 to step S90 is repeatedly executed until m becomes N. The upper limit value N is a natural number. In the above example of the generation timing of the index signal β, N is 10 to 40, but the generation timing is not limited to this, and may be 1, which is the smallest.

That is, when the fixed opening θ 1_ fix is set to an opening in which the predicted pressure Pp "does not completely exceed the" pressure target value Ps ", the processing of steps S40 to S90 is repeatedly executed, and the opening changing processing of step S100 is executed at a time point when it is determined that m is equal to N in step S90 (time t2 in fig. 12). On the other hand, when the fixed opening θ 1_ fix is set to an opening in a situation where the predicted pressure Pp "exceeds" the pressure target value Ps, the processing of steps S30 to S80 is repeatedly executed, and finally, the opening changing processing of step S100 is executed when it is determined that Pp > Ps in step S50.

(opening degree changing process)

In the opening degree change process, the estimation operation unit 210 in fig. 2 recalculates the opening degree target estimation value (here, this value is represented as θ se2), and sets the opening degree setting θ 1 output from the feedforward controller 220 to θ se 2. For example, in fig. 12 in the case of "not exceeding at all" in the rising case, the opening degree setting θ 1 is changed to θ se2 at time t2, and the pressure response of the pressure measurement value Pr which has changed so far as shown by the line L1 is changed to a pressure response as shown by a line L2. When it is determined in step S50 that the flow has passed to step S100, the pressure response and the like as shown in fig. 12 are not shown, and θ se2 > θ se are obtained from the opening degree target estimated value θ se2 which is recalculated.

In step S110, it is determined whether or not a condition for switching from the open control to the close control is satisfied, and if the condition is satisfied, the open control is terminated and the switch is made to the close control. As the skip condition, for example, it is conceivable that: a case where the pressure measurement value Pr is sufficiently close to the pressure target value Ps so that the difference between Pr and Ps becomes 5% or less of the magnitude of Ps, a case where the index signal β changes from a monotone decrease to a monotone increase, or the like.

When the open control is switched to the close control at time t3 in fig. 12, a constant opening setting θ se2 is output from the feedforward controller 220, and an opening setting θ 2 is output from the feedback controller 230. After the closing control is started, the pressure response of the pressure measurement value Pr changes as indicated by a line L3, and the pressure measurement value Pr converges almost to the pressure target value Ps at time t 4.

Note that, although the opening degree θ s is an opening degree at which the pressure balance value becomes the pressure target value Ps, when the opening degree θ 1(θ se) is set to θ 1 θ s with respect to the opening degree θ s, neither "exceeding" nor "completely not exceeding" may be determined. In this case, for example, when the calculation of the N _ timeout index signal β is performed after the opening degree setting θ 1 is fixed, that is, when the calculation cycle Δ t (for example, 10ms described above) is set, the on control may be switched to the off control at the time when the time N _ timeout × Δ t elapses. Wherein N _ timeout > N.

Fig. 13 is a diagram showing a comparative example, and shows a case where the pilot pressure Pp is used as an indicator of the determination in the case of "completely not exceeding". The determination that the fixed opening degree using the pilot pressure Pp eventually becomes the opening degree Pp < Ps is not determined until the pilot pressure Pp sufficiently converges to the pressure balance value (time t11 in fig. 13). Therefore, during this period, the response of the pressure measurement value Pr stalls, and the pressure adjustment time for bringing the pressure measurement value Pr closer to the pressure target value Ps after the jump to the close control at time t11 becomes longer.

On the other hand, when the index signal β is used, it can be determined that the pressure measurement value Pr is at an early stage of the rising process as at time t2 in fig. 12, and "does not exceed at all". Therefore, the time until the pressure measurement value Pr converges to the pressure target value Ps after the opening degree setting θ 1 is fixed to θ se can be made shorter than the case of using the pilot pressure Pp. Although the predicted pressure Pp is not shown in fig. 12, the predicted pressure Pp is also in the process of rising at time t 2.

(method of calculating opening degree target estimation value θ se)

An example of a method of calculating the opening degree target estimation value θ se will be described. Here, a method of calculating the opening degree target estimation value θ se using the plant gain (plant gain) Gp, which is a correlation between the opening degree θ and the pressure P, will be described. The controlled device gain Gp is defined by the following equation (20). Further, | (Δ P/Δ θ) | denotes an absolute value of (Δ P/Δ θ).

Gp＝|(ΔP/Δθ)|/P···(20)

As can be seen from equation (20), when the opening degree θ is taken as an input and the pressure P of the vacuum chamber 3 is taken as an output, the static gain characteristic of the pressure response of the lean gas in the vacuum chamber 3, which is the controlled equipment, is expressed by the pressure change with respect to the opening degree change, that is, the amount ((Δ P/Δ θ)/P) normalized by (Δ P/Δ θ) with respect to the pressure P. The controlled plant gain Gp (θ) is stored in the storage unit 23 in fig. 1 as a data table (θ, Gp) showing the relationship between the opening θ and the controlled plant gain Gp, for example.

When the pressure-regulated state as the equilibrium state is expressed as (θ, P), the pressure-regulated state before the opening degree change is expressed as (θ se, Pr), and the target pressure-regulated state is expressed as (θ se2, Ps). Using the definitional expression of expression (20), the relationship between the opening degree change Δ θ and the pressure change Δ P is expressed by expression (21).

ΔP＝-P×Gp(θ)×Δθ···(21)

The relationship between the voltage-regulated states (θ se, Pr) and the voltage-regulated states (θ se2, Ps) is expressed by the following expressions (22) and (23).

θ se2 ═ θ se + - [ d θ (integration range θ se to θ se2) · (22)

Ps ═ Pr +. clan dP (integral range Pr to Ps) · (23)

The integrals of the expressions (22) and (23) are actually expressed by adding the increase Δ θ of the opening degree and the increase Δ P of the pressure in each quasi-static state from the pressure regulation state (θ se, Pr) to the pressure regulation state (θ se2, Ps), and therefore θ se2 and Ps can be expressed as the expressions (24) and (25). In equation (24), Δ θ _ n (θ _ n) represents an opening degree increase Δ θ _ n when the opening degree θ _ n is used, and is, for example, an opening degree increase when Δ θ _1(θ _1) changes from the opening degree θ se to the opening degree θ _ 1. Likewise, Δ P _ n (P _ n) represents a pressure increase at the pressure P _ n.

θse2＝θse+ΣΔθ_n(θ_n)···(24)

Ps＝Pr+ΣΔP_n(P_n)···(25)

As for Δ θ _ n (θ _ n) in equation (24), an increment Δ θ _ n (θ _ n) may be provided according to each opening θ _ n as in equation (26). Regarding Δ P _ n (P _ n) in equation (25), an increase Δ P _ n (P _ n) at the pressure P _ n corresponding to the increase Δ θ _ n (θ _ n) at the opening θ _ n may be provided using the correlation between the opening θ and the pressure P. In the case of using the controlled plant gain Gp as the correlation, the increment Δ P _ n when the pressure P _ n is Δ P _ n (P _ n) is expressed by the following equation (27) to which the above equation (21) is applied. In equation (27), Δ θ _ n is Δ θ _ n (θ _ n), and Gp _ n is Gp (θ _ n).

Δθ_n＝Δθ_n(θ_n)···(26)

ΔP_n＝ΔP_n(P_n)＝-P_n×Gp_n×Δθ_n···(27)

When the equations (26) and (27) are substituted into the equations (24) and (25) and integrated, the opening degree value θ se2 and the pressure target value Ps in the pressure regulation state (θ se2, Ps) can be substantially achieved. Further, expressions (24) and (25) can be expressed in a modified manner as described below, and can be sequentially calculated.

θ_n+1＝θ_n+Δθ_n···(28)

P_n+1＝P_n+ΔP_n···(29)

The opening degree θ is cumulatively calculated by equations (26) and (28), and the pressure P is cumulatively calculated in order by equations (27) and (29). Then, when the value "P0 + Σ Δ P _ n (P _ n)" on the right side of the expression (25) as the cumulative calculated value of the pressure reaches (or exceeds) the next pressure value (here, the pressure target value Ps), the calculation is terminated. The opening degree of the integration operation when the pressure target value Ps is reached corresponds to the target opening degree estimation value θ se 2. Further, the method is applicable to obtain a practical approximate value even in a state that cannot be said to be a quasi-static state, and is therefore useful for obtaining a target opening degree estimation value.

(modification 1)

Fig. 14 is a flowchart for explaining modification 1 of the above embodiment. In the above embodiment, even in the case of "not exceeding at all", the opening degree is changed only once by the opening degree change processing, and then the control is shifted to the close control. However, the following occurs: the target opening degree estimation value θ se deviates from the pressure target value Ps due to the calculation error, and the pressure measurement value Pr cannot be brought close to the pressure target value Ps by one opening degree change. Therefore, in the control process shown in the flowchart of fig. 14, step S200 is added to the flowchart shown in fig. 11, and the opening degree based on the indicator signal β is changed to a predetermined upper limit number of times.

In the rising case shown in fig. 15, the determination using the index signal β is performed twice, and the opening degree setting θ 1 is changed to θ se2 and θ se 3. At this time, the target opening degree estimate value θ se2 calculated after the first determination is larger than the target opening degree θ s, and the indicator signal β monotonously decreases after the change. The target opening degree estimate value θ se3 calculated after the second determination is smaller than the target opening degree θ s, and the changed index signal β monotonously increases. Therefore, in step S110 in fig. 14, it is determined that the jump condition is satisfied (β is monotonically decreasing → monotonically increasing), and the open control is jumped to the closed control. For example, when the upper limit number of times in step S200 is two, and θ se3 > θ S in fig. 15, it is determined as yes in step S200 before it is determined as yes in step S110, and the control jumps from the open control to the closed control.

(modification 2)

In the flowchart of fig. 11 in which the pilot pressure Pp and the indicator signal β are used in combination, the pilot pressure Pp is used for the determination of "excess" as in step S50. However, the determination may be performed using the index signal β even in the case of "over". As can be seen from fig. 10, when the index signal β is used to determine "over", the index signal β is monotonically increased, and when the index signal β is determined to be "over". In this case, the flowchart of fig. 11 is modified as shown in fig. 16, for example, in modification 2.

When it is determined in step S10 of fig. 16 that the value of the opening degree measurement value θ r is equal to the opening degree setting θ 1_ fix and the indicator signal β is calculated in step S20, m1 and m2 are set to 0 and 0, respectively, in step S300. Next, when the indicator signal β is calculated in step S310, in step S320, it is determined whether the pilot pressure Pp "does not exceed" the pressure target value Ps at all, that is, whether β (previous time) > β (present time) is determined. If it is determined in step S320 that β (previous) > β (present), the process proceeds to step S330, where m1 is increased by 1 so that m1 becomes m1+ 1. In step S340, it is determined whether or not m1 indicating the number of times β (previous) > β (present) is determined to have reached upper limit N1, and if it has reached (m1 is N1), the process proceeds to step S100, and if it has not reached (m1 < N1), the process returns to step S310.

On the other hand, if it is determined in step S320 that "β (previous) > β (current)", the flow proceeds to step S322, and after m1 is set to 0, it is determined in step S324 whether "exceeds", that is, whether "β (previous) < β (current)". If it is determined in step S324 that "β (previous) < β (present)", the process proceeds to step S326, where m2 is increased by 1 so that m2 becomes m2+1, and then the process proceeds to step S328. On the other hand, if it is determined in step S324 that "β (previous) < β (present)", the process proceeds to step S325, where m2 is set to 0, and the process returns to step S310. In step S328, it is determined whether or not m2 indicating the number of times β (previous time) < β (present time) is determined to have reached the upper limit value N2, and if it has reached (m2 is N2), the routine proceeds to step S100, and if it has not reached (m2 < N2), the routine proceeds to step S310.

As described above, when the number of times "β (previous) > β (present)" is determined to have reached the upper limit N1 by repeating the processing of steps S310 to S340, or when the number of times "β (previous) < β (present)" is determined to have reached the upper limit N2 by repeating the processing of steps S310 to S328, the opening degree change processing is performed in step S100. Then, in step S110, it is determined whether or not a condition for jumping from the open control to the close control is satisfied, and when the condition is satisfied, the open control is terminated and the jump to the close control is made.

As described above, the predicted pressure Pp is an estimated pressure value after t seconds from the time point at which the pressure measurement value Pr is measured, and depends on the estimated value of the effective exhaust velocity Se or the flow rate Qin based on the reference gas. In general, the gas type of the reference gas is different from the gas type of the gas that actually flows in many cases, and therefore the error of the predicted pressure Pp may become large.

On the other hand, as can be seen from the formula (1) for defining the index signal β, the index signal β is calculated based on the target pressure value Ps and the actually measured pressure measurement value Pr, and the index signal β reflects the actual gas type or gas flow rate. Therefore, the reliability of the determination can be improved as compared with the determination using the "excess" of the predicted pressure Pp.

(modification 3)

In the above-described embodiment, modification 1 and modification 2, the case where both the "exceeding" and the "completely not exceeding" occur was described as an example. However, when the opening degree change amount in the opening control is not so large as to change from the fourth quadrant to the third quadrant in fig. 4, a flowchart corresponding to only the case of "not exceeding completely" as shown in fig. 17 may be employed. The flowchart shown in fig. 17 eliminates the processing of step S40 and step S50 from the flowchart shown in fig. 14. If the processing from step S30 to step S90 is repeated N times and it is determined that "no more than is", the opening degree change processing of step S100 is performed.

In addition, similarly to the case of the flowchart of fig. 14, it is considered that the pressure measurement value Pr cannot be brought to the vicinity of the pressure target value Ps by one opening degree change, and the opening degree based on the index signal β is changed up to a predetermined upper limit number of times as in step S200. When the opening degree setting θ 1(θ se) is θ 1 θ s and it is not determined that "no more than is" not to be exceeded ", the control is switched from the on control to the off control at a time point when the N _ timeout index signal β is calculated after the opening degree setting θ 1 is fixed.

(modification 4)

In the first embodiment, the indicator signal β (═ dPr/dt)/(Ps-Pr) defined by formula (1) is introduced as the indicator signal in place of the pilot pressure Pp. However, the indicator signal instead of the pilot pressure Pp is not limited to the indicator signal defined by the formula (1), and various similar signals as described below can be applied.

Normalized to a dimensionless quantity of the indicator signal β 1

An index signal β 1 defined by the following equation (30) is introduced from a data set Se _ r (θ r) indicating the correlation among the volume V of the vacuum chamber 3, the effective exhaust velocity Se, and the opening degree measurement value θ r. By normalizing to the dimensionless amount, the versatility of the determination threshold can be improved even when the conditions such as the gas flow rate value are changed.

β1＝(V/Se_r(θr))×[(dPr/dt)/(Ps-Pr)]···(30)

An indicator signal β 2 that is positive with accuracy

In principle, both the rising case and the falling case were judged in a range where "(dPr/dt)/(Ps-Pr)" becomes a positive value. However, in preparation for disturbances such as sudden flow rate changes, the absolute value of both the denominator and the numerator is used as in equations (31) and (32), and thus the indicator signal β 2 that is a positive value can be obtained.

β 2 | dPr/dt |/| Ps-Pr | · (31) or

β2＝(V/Se_r(θr))×|dPr/dt|/|Ps-Pr|···(32)

It is understood by those skilled in the art that the above-described exemplary embodiments and modifications are specific examples of the following forms.

[1] A valve control device according to an aspect of the present invention controls an opening degree of a vacuum valve attached to a vacuum chamber by opening control, and includes: an opening setting unit that outputs an opening set value for opening control; a first determination unit that determines that a pressure balance value in a case where the opening degree set value is a fixed value does not exceed a target valve control pressure value during a predetermined period within a fixed period in which the opening degree set value is the fixed value; and an opening degree control unit that controls the opening degree based on the determination result of the first determination unit.

For example, as shown in fig. 17, in a predetermined period including time t1 during which the opening degree set value θ 1 becomes a constant value θ 1_ fix, it is determined that the pressure balance value Pe (θ 1_ fix) does not exceed the pressure target value Ps based on the calculated index signal β (previous time) and the index signal β (present time). Therefore, it is possible to determine that the pre-pressure P or the pressure measurement value Pr does not exceed the pressure target value Ps as early as possible without waiting for the pre-pressure P or the pressure measurement value Pr to converge to a pressure balance value that does not exceed the pressure target value Ps, and by performing further opening degree control based on the determination result, it is possible to achieve a reduction in the pressure regulation time.

[2] The valve control device according to [1], further comprising: and a second determination unit configured to determine that the pressure balance value exceeds the pressure target value or that the predicted pressure of the vacuum chamber after elapse of the prediction time based on the fixed value exceeds the pressure target value, wherein the opening degree control unit controls the opening degree based on the determination results of the first determination unit and the second determination unit.

For example, as shown in fig. 12, in a predetermined period including time t1 during which the opening degree set value θ 1 becomes a constant value θ 1_ fix, it is determined that the pressure balance value Pe (θ 1_ fix) does not exceed the pressure target value Ps based on the calculated index signal β (previous time) and the index signal β (present time). Further, as in step S324 of fig. 16, it is determined that the pressure balance value Pe (θ 1_ fix) exceeds the pressure target value Ps based on the indicator signal β (previous time) and the indicator signal β (present time) during the predetermined period, or as in step S50 of fig. 11, it is determined that the predicted pressure Pp exceeds the pressure target value Ps when the predicted pressure Pp becomes Pp > Ps.

Therefore, the excess or the non-excess can be determined as early as possible without waiting for the pre-pressure Pp or the pressure measurement value Pr to converge to a pressure balance value that does not exceed the pressure target value Ps, and the pressure regulation time can be shortened by performing further opening degree control based on the determination result.

[3] The valve control device according to [2], wherein the first determination unit determines that the pressure balance value does not exceed the pressure target value based on a ratio of a time rate of change of a pressure measurement value to a difference value between the pressure measurement value and the pressure target value, and the second determination unit determines that the pressure balance value exceeds the pressure target value based on the ratio.

The index signal β defined by the formula (1) is a ratio of a time change rate (dPr/dt) of the pressure measurement value Pr to a difference value (Ps-Pr) between the pressure measurement value Pr and the pressure target value Ps. By setting this amount, the ratio (i.e., the index signal β) monotonically increases in the case of "exceeding" and monotonically decreases in the case of "not exceeding at all". Therefore, by studying whether the ratio monotonically increases or monotonically decreases during a predetermined period within the fixed period, it can be determined that the ratio exceeds or does not exceed the pressure target value Ps even if the pressure measurement value Pr does not converge to the pressure target value Ps during the predetermined period.

In addition, although the formula (1) is defined as (dPr/dt)/(Ps-Pr), even if the index signal is an index signal in which the denominator and the numerator are reversed, the index signal monotonically decreases when exceeding the index signal and monotonically increases when not exceeding the index signal, and thus it is possible to determine whether the index signal monotonically increases or monotonically decreases to determine whether the index signal monotonically exceeds the index signal.

[4] The valve control device according to [3], wherein the ratio is set to "(dPr/dt)/(Ps-Pr)" when the pressure measurement value is Pr, the pressure target value is Ps, and the time derivative of the pressure measurement value is (dPr/dt). By setting the ratio in this manner, it is possible to determine that the excess does not exceed by studying whether the ratio monotonically increases or monotonically decreases in a predetermined period within the fixed period.

[5] The valve control device according to any one of [2] to [4], comprising: and an estimation unit that estimates a target opening degree estimation value corresponding to a pressure target value based on the opening degree set value and a pressure measurement value at the time of the opening degree set value, wherein the opening degree control unit controls the opening degree to the target opening degree estimation value based on determination results of the first determination unit and the second determination unit.

For example, as in the processing shown in fig. 11, when it is determined that Pp > Ps in step S50 or when it is determined that "β (previous) > β (present)" for N times as in step S70 and step S90, the opening degree setting θ 1 is set to the target opening degree estimation value θ se estimated and calculated by the estimation calculation unit 210, and the opening degree of the valve body 12 is controlled to the target opening degree estimation value θ se. As a result, the pressure measurement value Pr can be made closer to the pressure target value Ps.

[6] A vacuum valve of one aspect includes: a valve body; a valve body driving part for driving the valve body; and a valve control device according to any one of [1] to [5], wherein the valve drive unit is controlled to control an opening degree of the valve body. This can further shorten the pressure adjustment time by the vacuum valve.

While the various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments that can be conceived within the scope of the technical idea of the present invention are also included in the scope of the present invention.

Claims (6)

1. A valve control device that controls an opening degree of a vacuum valve attached to a vacuum chamber by opening control, comprising:

an opening setting unit that outputs an opening set value for opening control;

a first determination unit that determines that a pressure balance value in a case where the opening degree set value is a fixed value does not exceed a target valve control pressure value during a predetermined period within a fixed period in which the opening degree set value is the fixed value; and

and an opening degree control unit that controls the opening degree based on the determination result of the first determination unit.

2. The valve control apparatus according to claim 1, further comprising:

a second determination unit configured to determine that the pressure balance value exceeds the pressure target value or that a predicted pressure of the vacuum chamber after a lapse of a prediction time based on the predetermined value exceeds the pressure target value,

the opening degree control unit controls the opening degree based on the determination results of the first determination unit and the second determination unit.

3. The valve control apparatus according to claim 2,

the first determination unit determines that the pressure balance value does not exceed the pressure target value based on a ratio of a time rate of change of the pressure measurement value to a difference value between the pressure measurement value and the pressure target value,

the second determination portion determines that the pressure balance value exceeds the pressure target value based on the ratio.

4. The valve control apparatus according to claim 3,

when the pressure measurement value is Pr, the pressure target value is Ps, and the time derivative of the pressure measurement value is (dPr/dt), the ratio is set to "(dPr/dt)/(Ps-Pr)".

5. The valve control apparatus according to any one of claims 2 to 4, comprising:

an estimating unit that estimates a target opening degree estimation value corresponding to a pressure target value based on the opening degree set value and a pressure measurement value at the time of the opening degree set value,

the opening degree control unit controls the opening degree to the target opening degree estimation value based on the determination results of the first determination unit and the second determination unit.

6. A vacuum valve, comprising:

a valve body;

a valve body driving part for driving the valve body; and

the valve control device according to any one of claims 1 to 4, wherein the valve body drive portion is controlled to control an opening degree of the valve body.

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