JP2021022223A - Valve control device and vacuum valve - Google Patents

Abstract

To provide a valve control device capable of shortening a pressure regulation time.SOLUTION: A valve control device 2 is provided with a feed-forward controller 220 for controlling by open control an opening degree of a vacuum valve mounted in a vacuum chamber and for outputting an opening degree setting value θ1 of the open control, and a pressure regulation controller 21 for determining that a pressure equilibrium value in the case of a constant value does not exceed a pressure target value Ps of valve control in a predetermined period within a fixed period in which the opening degree setting value θ1 becomes the constant value. When determining that the pressure equilibrium value does not exceed the pressure target value Ps, the pressure regulation controller 21 controls the opening degree based on the result of determination.SELECTED DRAWING: Figure 2

Description

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

In a vacuum processing device such as a CVD device, a vacuum valve for pressure regulation is provided between the process chamber and the vacuum pump (see, for example, Patent Document 1), and the opening degree of the vacuum valve is controlled to automatically adjust the chamber pressure to a predetermined pressure. I try to adjust. In the vacuum valve described in Patent Document 1, rough adjustment is performed by open control up to the vicinity of the pressure target value, and further, the control is switched to close control so that the pressure target value is finely adjusted.

JP-A-2018-106718

By the way, in the invention described in Patent Document 1, when the opening degree is fixed during open control, whether the predicted pressure Pp exceeds the pressure target value Ps (Pp> Ps) or does not exceed (Pp ≦ Ps). Is being judged. However, regarding the determination that the predicted pressure Pp does not exceed the pressure target value Ps, it is difficult to determine that the predicted pressure Pp does not exceed the pressure target value Ps at the stage where the predicted pressure Pp tends to increase. As a result, there is a problem that the pressure adjusting time becomes longer than necessary.

The valve control device according to the first aspect of the present invention is an opening degree setting unit that outputs an open control opening degree setting value in a valve control device that controls the opening degree of a vacuum valve mounted in a vacuum chamber by open control. A first determination unit that determines that the pressure equilibrium value in the case of the constant value does not exceed the pressure target value of the valve control in a predetermined period within the fixed period in which the opening setting value becomes a constant value. It includes an opening degree control unit that controls the opening degree based on the determination result of the first determination unit.
The vacuum valve according to the second aspect of the present invention is the valve body, a valve body driving unit that drives the valve body, and the valve control device that controls the valve body driving unit to control the opening degree of the valve body. And.

According to the present invention, the pressure adjustment time can be shortened.

FIG. 1 is a block diagram showing a schematic configuration of a vacuum valve mounted on a vacuum processing apparatus. FIG. 2 is a functional block diagram of the vacuum valve and the valve control device. FIG. 3 is a diagram illustrating a pressure regulation logic in open control. FIG. 4 shows an example of the locus of points (θr, Pr) by open control. FIG. 5 is a diagram for explaining the relationship between the measured pressure value Pr and the predicted pressure Pp, and shows the case where Pe (θr)> Ps. FIG. 6 is a diagram for explaining the relationship between the measured pressure value Pr and the predicted pressure Pp, and shows the case where Pe (θr) <Ps. FIG. 7 is a diagram showing the determination conditions based on the predicted pressure Pp when “exceeding” and “not exceeding”, and the opening degree relationship and 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 pressure (pressure measurement value Pr and predicted pressure Pp), index signal β, and opening degree setting θ1 when the opening degree setting θ1 is fixed to the value θ1_fix. FIG. 10 is a diagram showing the determination conditions based on the index signal β when “exceeds” and “does not exceed at all”, and the opening degree relationship and pressure relationship at that time. FIG. 11 is a flowchart showing an example of control processing when the predicted pressure Pp and the index signal β are used in combination. FIG. 12 is a diagram showing changes in the pressure measurement value Pr, the index signal β, and the opening degree settings θ1 and θ2 in the up case. FIG. 13 is a diagram showing a comparative example. FIG. 14 is a flowchart for explaining the first modification. FIG. 15 is a diagram illustrating an up case in the first modification. FIG. 16 is a flowchart for explaining the second modification. FIG. 17 is a flowchart for explaining the modified example 3.

Hereinafter, embodiments for carrying out 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 mounted on a vacuum processing apparatus. The vacuum valve is composed of a valve body 1 provided with a valve body 12 and a valve control device 2 for controlling valve body drive. The valve body 1 is mounted between the vacuum chamber 3 and the vacuum pump 4. A gas such as a process gas is introduced into the vacuum chamber 3 via the flow rate controller 32. The flow rate controller 32 is a device that controls the flow rate Qin of the gas introduced into the vacuum chamber 3, and is controlled by the main controller (not shown) of the vacuum processing device provided with the vacuum chamber 3. The pressure in the vacuum chamber 3 (chamber pressure) is measured by the vacuum gauge 31, and the pressure measurement value Pr is input to the valve control device 2.

The valve body 1 is provided with a motor 13 for opening and closing the valve body 12. The valve body 12 is opened and closed by the motor 13. The motor 13 is provided with an encoder 130 for detecting the 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 θr of the valve body 12 (hereinafter, referred to as an opening degree measurement value θr).

The valve control device 2 that controls the valve body 1 includes a pressure regulating controller 21, a motor drive unit 22, and a storage unit 23. In addition to the pressure measurement value Pr and the opening degree measurement value θr described above, the pressure target value Ps of the vacuum chamber 3 is input to the valve control device 2 from the main controller of the vacuum processing device described above. The storage unit 23 stores parameters required for valve control (for example, data on effective exhaust speed Se, plant gain Gp, etc., which will be described later). The motor drive unit 22 includes an inverter circuit for driving the motor and a motor control unit that controls the motor, and the opening degree measurement value θr from the encoder 130 is input. The chamber pressure Pr measured by the vacuum gauge 31 is input to the pressure adjusting controller 21, and the target pressure Ps of the vacuum chamber 3 is input from the main controller of the vacuum processing device described above.

The valve control device 2 includes, for example, an arithmetic processing device such as a microcomputer having a CPU, a memory (ROM, RAM), peripheral circuits, and the like, and a pressure control controller 21 and a motor drive unit are provided by a software program stored in the ROM. The functions of the 22 motor control units are realized. The storage unit 23 is composed of the memory of the microcomputer. Further, it may be configured by a digital arithmetic unit such as FPGA (Field Programmable Gate Array) and its peripheral circuit.

FIG. 2 is a functional block diagram of the valve body 1 and the valve control device 2. The pressure control controller 21 includes an estimation calculation unit 210, a feedforward controller 220, and a feedback controller 230. The opening degree measurement value θr detected by the encoder 130 is input to the motor drive unit 22 and the estimation calculation unit 210.

Also in the present embodiment, as in the invention of Patent Document 1 described above, rough adjustment is performed by open control up to the vicinity of the pressure target value, and further, the control is switched to close control and fine adjustment is performed to reach the pressure target value. In the pressure regulating controller 21, the estimation calculation unit 210 and the feedforward controller 220 correspond to the open control unit, and the subtractor and the feedback controller 230 that generate the deviation ε (= Pr-Ps) correspond to the closed control unit. ..

The pressure measurement value Pr, the pressure target value Ps, and the opening degree measurement value θr are input to the estimation calculation unit 210 of the open control unit. The estimation calculation unit 210 generates an index signal β indicating a change tendency of the target opening degree estimated value θse, the predicted pressure Pp, and the pressure measured value Pr based on the pressure measured value Pr, the pressure target value Ps, and the opening degree measured value θr. Calculate. In general, even if the valve body opening is fixed to a constant value, it takes a certain amount of time for the chamber pressure to reach the pressure equilibrium value corresponding to the valve body opening. The predicted pressure Pp is an estimated pressure value t seconds after the measured pressure value Pr is measured. The method for estimating the predicted pressure Pp is described in detail in JP-A-2018-106718 described above, and the description thereof will be omitted here. Further, the calculation method of the target opening degree estimated value θse and the index signal β will be described later.

The feedforward controller 220 of the open control unit outputs the opening degree setting θ1 based on the target opening degree estimated value θse and the index signal β. Further, the feedback controller 230 of the close control unit outputs the opening degree setting θ2 based on the deviation ε = Pr−Ps. The output opening degree setting θ1 and the opening degree setting θ2 are added, and the addition result is input to the motor drive unit 22 as the opening degree setting θset. The motor drive unit 22 drives the motor 13 based on the opening degree setting θset and the opening degree measurement value θr input from the encoder 130.

As will be described later, in the present embodiment, the determination using the predicted pressure Pp during the open control and the determination using the index signal β regarding the pressure equilibrium value when the opening degree setting θ1 is fixed are used together. The determination using the predicted pressure Pp is performed according to the pressure adjustment logic shown in FIG. In the following, the pressure adjustment logic based on the predicted pressure Pp of FIG. 3 will be described first, and then the method of setting the index signal β and the method of determining the index signal β will be described.

The coordinate system shown in FIG. 3 is a coordinate system θ−P whose origin is a point (θse, Ps). The target opening degree estimated value θse is an estimation calculation of the opening degree of the valve body 12 at the pressure target value Ps. In such a coordinate system θ−P, the opening degree θ is determined based on which of the first to fourth quadrants the points (θr, Pr) are in, and the magnitude relationship between the predicted pressure Pp and the pressure target value Ps. Determine whether to control in the open direction or the closed direction.

When the points (θr, Pr) before the opening change are in the second quadrant and the fourth quadrant, the opening θ is adjusted in the direction of the opening target estimated value θse. As a result, the measured pressure value Pr changes in the direction of the pressure target value Ps. That is, in the case of the second quadrant, the pressure decreases, and in the case of the fourth quadrant, the pressure increases. The starting point of the control start is either the 2nd or 4th quadrant, the 4th quadrant in the case of the up case where the pressure rises from the starting pressure Pstt, and the 1st in the case of the down case where the pressure drops from the starting pressure Pstt. There are two quadrants.

On the other hand, when the points (θr, Pr) before the opening change are in the first quadrant and the third quadrant, the opening adjustment direction is set according to the magnitude relationship between the predicted pressure Pp and the pressure target value Ps. .. In the first quadrant, when the predicted pressure Pp is larger than the pressure target value Ps such as Pp> Ps, the opening is adjusted in the direction of increasing the opening (direction indicated by the arrow pointing to the right), or the circle. As shown by 50, the opening value is maintained as it is. On the contrary, when Pp ≦ Ps, the opening degree is adjusted in the direction of reducing the opening degree (the direction indicated by the arrow pointing to the left). In the third quadrant, when Pp> Ps, the opening degree is adjusted in the direction of increasing the opening degree (the direction indicated by the arrow pointing to the right). On the contrary, when Pp ≦ Ps, the opening degree is adjusted in the direction of reducing the opening degree (the direction indicated by the arrow pointing to the left), or the opening degree value is maintained as it is as shown by the circle 50.

FIG. 4 shows an example of the locus of points (θr, Pr) by open control when the coordinates (θr, Pr) of the starting point of control are in the fourth quadrant as in points A1 and B1. .. In the example where the starting point is the point A1, the opening is changed by the open control to move to the point A2 near the target opening estimated value θse. When the pressure measurement value Pr becomes close to the target opening degree estimated value θse, the closing control is performed.

In the example where the starting point is the point B1, the movement is moved to the point B2 in the third quadrant by changing the opening degree by the open control. Here, the predicted pressure Pp estimated and calculated when moving 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. The measured pressure value Pr and the estimated predicted pressure Pp continue to increase even while the opening degree is maintained, and the positions of the points (θr, Pr) move upward. Then, when the distance to the point B3 is reached, the predicted pressure Pp becomes Pp> Ps, and the opening degree is changed in the direction of increasing. As a result, the opening is changed to move to the point B4 near the target opening estimated value θse. When the pressure measurement value Pr becomes close to the target opening degree estimated value θse, the closing control is performed.

When the opening measurement value θr finally becomes the target opening estimated value θse by the open control, the opening setting θ1 output from the feedforward controller 220 in FIG. 2 remains fixed at that value and is closed from the open control. Switch to control. When the control is switched to the close 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 θ2 based on the deviation ε = Pr−Ps. Usually, the feedback controller 230 is composed of a proportional gain and an integrated gain (so-called PI gain). The motor drive unit 22 controls the opening degree based on the opening degree setting θset = θ1 (fixed) + θ2. The opening measurement value θr is θr = θ1 + θ2 unless the valve body 12 is moving at high speed.

Until the start of the close control, the pressure measurement value Pr is input to the subtraction point instead of the pressure target value Ps. Therefore, at the time of open control, the pressure deviation ε = 0 is input to the feedback controller 230, and the opening degree setting θ2 = 0 is output from the feedback controller 230.

By the way, 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 (for example, a time longer than the control cycle such as t = 0.4 seconds) as described above. 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 of B3, and the valve body opening is the target opening estimated value θse. It has been changed direction and moved to point B4.

FIG. 5 is a diagram showing the relationship between the measured pressure value Pr and the predicted pressure Pp. The horizontal axis represents time and the vertical axis represents pressure. The lines L1 and L2 show the temporal transition of the pressure measurement value Pr and the predicted pressure Pp when the valve body opening degree is fixed to the opening degree measurement value θr at the point B2. Since the predicted pressure Pp is the predicted pressure t seconds after the time when the measured pressure value Pr is measured, the line L2 is deviated above the line L1 of the pressure measured value Pr. At the time point B2, the predicted pressure Pp is Pp <Ps with respect to the pressure target value Ps.

However, when the measured pressure value Pr rises in the pressure direction in the equilibrium state with the passage of time, the predicted pressure Pp also rises accordingly, and the predicted pressure Pp exceeds the pressure target value Ps at the point B3. When more time elapses while the opening measurement value is fixed to θr, the pressure measurement value Pr also exceeds the pressure target value Ps, and when a sufficient time elapses, the pressure measurement value Pr becomes the pressure equilibrium value at the opening measurement value θr. (Pressure value in equilibrium state) Converges to Pe (θr). In the equilibrium state, the predicted pressure Pp also converges to Pe (θr).

For this reason, the measured opening degree θr is smaller than the opening degree corresponding to the pressure target value Ps, and it is necessary to readjust in the direction of increasing the valve body opening degree. By using the predicted pressure Pp, it is possible to determine that readjustment is necessary at a time point before the actual pressure measured value Pr exceeds the pressure target value Ps, that is, at the timing B3 when the predicted pressure Pp becomes Pp> Ps. Is.

On the other hand, in the control example of A1 → A2 shown in FIG. 4, the predicted pressure Pp does not exceed the pressure target value Ps. In this case, it is unclear at what point it should be determined that the predicted pressure Pp does not exceed the pressure target value Ps. For example, when the pressure rise rate of the predicted pressure Pp becomes almost zero, it can be determined that the predicted pressure Pp does not exceed the pressure target value Ps, but it is determined that the pressure rise rate becomes almost zero. It takes a long time to do so. Therefore, there is a problem that the pressure adjusting time becomes longer than necessary. By the way, a control example such as A1 → A2 is a rare case when the calculation error of the target opening degree estimated value θse is small. However, this is often the case when the calculation error of the estimated target opening degree θse is large, and as a result, the deviation is larger than the true target opening degree θs. In particular, it is known that the difference is large between cases where the gas type (molecular weight) and the gas flow rate are significantly different.

In general, a calculation error of the estimated target opening degree θse is unavoidable, and when the deviation from the true target opening degree θs with respect to the pressure target value Ps is larger than the true target opening degree θs, the pressure of the measured pressure value Pr is shown in FIG. The equilibrium value (pressure value in the equilibrium state) Pe (θr) is Pe (θr) <Ps. In this case, the pressure equilibrium value Pe (θr) deviates downward from the drawing with respect to the pressure target value Ps, and the predicted pressure Pp does not exceed the pressure target value Ps at all.

FIG. 4 shows a case where the pressure target value Ps is higher than the pressure Pstt at the start of pressure regulation in the up case, but even in the case where the pressure target value Ps is lower than the pressure Pstt at the start of pressure regulation in the down case. There are cases where the predicted pressure Pp exceeds the pressure target value Ps and cases where it does not exceed at all. In the case of the down case, Ps <Pstt, so that the predicted pressure Pp "exceeds" the pressure target value Ps is when Pp <Ps, and "does not exceed at all" is when Pp> Ps. is there. 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 adjusting time becomes longer than necessary. The problem arises.

FIG. 7 summarizes the determination conditions based on the predicted pressure Pp in the cases of “exceeding” and “not exceeding at all” described above, and the opening relationship and pressure relationship at that time. The opening degree θ1_1 in FIG. 7 is the opening degree setting θ1 at the timing when the open control period is predicted and determined, and Pe (θ1_1) is the pressure equilibrium value at the opening degree θ1_1. The prediction determination timing is set to a timing at which the opening degree θ is fixed to be constant. Further, the relationship is described on the premise that the estimated target opening degree θse has an error from the true target opening degree θs.

In the up case (Pstt <Pr), in the situation where the predicted pressure Pp “exceeds (Pp> Ps)” the pressure target value Ps, the point (θr = θ1_1, Pr) is in the third quadrant as shown at point B2 in FIG. There is, and the opening degree θ1_1 set as θ1_1 ≦ θse is θ1_1 <θs. That is, θ1_1 ≦ θse <θs, and the pressure relationship is Pstt <Pr <Ps <Pe (θse) ≦ Pe (θ1_1).

In the up case (Pstt <Pr), in the situation where the predicted pressure Pp "does not exceed the pressure target value Ps at all (Pp <Ps)", the point (θr = θ1_1, Pr) is the fourth point as shown at point A2 in FIG. In the quadrant, the opening degree θ1_1 set as θ1_1 ≧ θse is θ1_1> θs. That is, θ1_1 ≧ θse> θs, and the pressure relationship is Pstt <Pr <Pe (θ1_1) ≦ Pe (θse) <Ps.

In the down case (Pstt> Pr), in the situation where the predicted pressure Pp “exceeds” the pressure target value Ps (Pp <Ps), the opening degree θ1_1 set as θ1_1 ≧ θse is θ1_1> θs. That is, θ1_1 ≧ θse> θs, and the pressure relationship is Pe (θ1_1) ≦ Pe (θse) <Ps <Pr <Pstt.

In the down case (Pstt> Pr), in the situation where the predicted pressure Pp “does not exceed the pressure target value Ps at all (Pp> Ps)”, the opening degree θ1_1 set as θ1_1 ≦ θse becomes θ1_1 <θs. There is. That is, θ1_1 ≦ θse <θs, and the pressure relationship is Ps <Pe (θse) ≦ Pe (θ1_1) <Pr <Pstt.

(Introduction of index signal β)
In this embodiment, the index signal β is defined by the following equation (1). For the pressure measurement value Pr of the vacuum chamber 3, the exhaust equation represented by the following equation (2) is established, and the numerator (dPr / dt) of the index signal β is a quantity based on the exhaust equation.
β = (dPr / dt) / (Ps-Pr)… (1)
V × (dPr / dt) ＋ Se × Pr ＝ Qin… (2)

In the formula (2), Qin on the right side is 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 value Pr, and Se is the effective exhaust velocity of the vacuum exhaust system with respect to the exhaust of the vacuum chamber 3. The effective exhaust speed Se is an amount determined by the conductance determined by the chamber structure and the opening degree θr of the valve body 12 and the exhaust speed of the vacuum pump 4. The relationship between the opening degree θ of the valve body 12 and the effective exhaust speed Se is generally a monotonically increasing relationship as shown in FIG.

Normally, when the vacuum valve is mounted on the vacuum chamber 3 and used, an initial calibration operation related to the effective exhaust speed Se, that is, an initial calibration operation related to valve body control is performed. Generally, the gain calibration of the controller is performed according to the volume of the vacuum chamber 3, the sensitivity of the valve body, etc. under the typical gas of the process conditions to be applied or the average gas conditions (gas type, gas flow rate). Is done. As an average condition, for example, the average molecular weight of the mixed gas is obtained, and a gas type that is relatively easy to handle is often substituted.

The semiconductor process in the vacuum chamber 3 in which the vacuum valve is mounted is derived from a large number of pressure regulation events in which various conditions of the gas type introduced into the vacuum chamber 3, the gas flow rate Qin, and the pressure target value Ps are changed at predetermined time intervals. It is composed. In each pressure adjustment event, the gas flow rate is converged to a predetermined flow rate value by the flow rate controller 32 (see FIG. 1) immediately after the start, and in parallel, the valve body opening is adjusted to control the effective exhaust speed Se. The chamber pressure (measured pressure value Pr) is converged to the pressure target value Ps.

Generally, the flow rate control convergence completion timing by the flow rate controller 32 is earlier than the pressure control convergence completion timing by the vacuum valve. Further, it can be considered that the flow rate values are substantially converged even at the prediction determination timing at the time of open control in the present embodiment. That is, it is considered that the gas flow rate Qin converges to a constant flow rate value Qin0, and Qin = Qin0 = a constant value.

The prediction determination timing is set to a timing at which the opening is fixed to a constant value, and the opening at the fixed timing is expressed as θ1_fix. In the following, the effective exhaust gas velocity Se (θ1_fix) corresponding to the opening degree θ1_fix will be referred to as Se_fix, and the effective exhaust gas velocity Se (θs) corresponding to the opening degree θs at the pressure target value Ps will be referred to as Se0. At this time, the above-mentioned flow rate value Qin0 is expressed by the following equation (3). Pe (θ1_fix) is the pressure equilibrium value at the opening degree θ1_fix.
Qin0 ＝ Se0 × Ps ＝ Se_fix × Pe (θ1_fix)… (3)

From the equation (3), the pressure equilibrium value Pe (θ1_fix) is expressed by the following equation (4). Further, the exhaust equation when the opening degree is fixed to θ1_fix is expressed as the following equation (5).
Pe (θ1_fix) = (Se0 / Se_fix) × Ps… (4)
V × (dPr / dt) ＋ Se_fix × Pr ＝ Qin0… (5)

From the formulas (4) and (5), the numerator and denominator of the formula (1) giving the above-mentioned index signal β can be transformed as in the following formulas (6) and (7).
Molecule = (dPr / dt)
= (Se0 x Ps-Se_fix x Pr) / V
= (Se_fix / V) × {(Se0 / Se_fix) × Ps-Pr}… (6)
Fraction = (Ps-Pr)
= {(Se0 / Se_fix) x Ps-Pr}-{(Se0 / Se_fix) x Ps-Ps} ... (7)

Therefore, the index signal β is expressed by the following equation (8). In the formula (8), only the pressure measurement value Pr is a time-varying amount, and changes with time as Pr → Ps. Other quantities are time-invariant quantities (constant values).
β = (Se_fix / V) / [1-{(Se0 / Se_fix) × Ps-Ps} / {(Se0 / Se_fix) × Ps-Pr}]
… (8)

(Judgment method using index signal β)
Hereinafter, the determination method in the four cases shown in FIG. 7 will be described using the index signal β given by the equation (8). Here, applying that the relationship between the opening degree θ and the effective exhaust velocity Se has a monotonous increase relationship as shown in FIG. 8, for example, if θ1_fix> θs, it can be said that Se_fix> Se0. In the following description, the relationship shown in FIG. 8 will be applied. First, the case of "not exceeding" which becomes a problem when the predicted pressure Pp is used will be described, and then the case of "exceeding" will be described.

[1. When "does not exceed at all" in the up case]
The measured pressure value Pr during the pressure rise satisfies the relationship of Pstt <Pr <Pe (θ1_1) ≤ Pe (θse) <Ps as described in FIG. As described above, since θ1_1 is collectively expressed as θ1_fix, the relationship of the following equation (9) can be obtained from the relation of Pr <Pe (θ1_fix) <Ps and the equation (4).
Pr <(Se0 / Se_fix) x Ps <Ps ... (9)

Here, when F (Pr) of the following equation (10) is used, the right side denominator of the equation (8) is expressed as 1 + F (Pr).
F (Pr) =-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pr}
… (10)
From equation (9), it can be seen that {(Se0 / Se_fix) × Ps-Ps} <0, {(Se0 / Se_fix) × Ps-Pr}> 0 holds, and F (Pr)> 0. Therefore, F (Pr) (that is, the denominator on the right side of the equation (8)) becomes a positive value, and even if the pressure measurement value Pr changes with time, the index signal β = (dPr / dt) / (Ps-Pr) remains. It turns out that it is always positive.

In the case of an up-case where the pressure rises from the pressure Pstt at the starting point of control, the pressure measurement value Pr is Pr> Pstt, so {(Se0 / Se_fix) × Ps-Pstt}> {(Se0 / Se_fix) × Ps- The following equation (11) holds from the relation of Pr}> 0.
{(Se0 / Se_fix) x Ps-Pr} / {(Se0 / Se_fix) x Ps-Pstt} <1 ... (11)
The magnitude relationship between F (Pr) of equation (10) multiplied by the left side of equation (11) and F (Pr) is as shown in equation (12).
F (Pr)>-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}
… (12)

Since the right-hand side denominator of equation (8) is 1 + F (Pr) and is a positive value, the following equation (13) holds.
(Right side denominator)> 1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}
1 / (Right side denominator) <1 / [1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}]
… (13)
Since (Se_fix / V) in the equation (8) is a positive value, the index signal β satisfies the following equation (14) from the relation of the equation (13).
β <(Se_fix / V) / [1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}]
… (14)

In the up case, the pressure measurement value Pr in the equation (8) of the index signal β rises from the pressure Pstt at the starting point. As described above, F (Pr) contained in the right side denominator = 1 + F (Pr) of the equation (8) is a positive value, and the smaller Pr is, the smaller it is. Therefore, the right side denominator = 1 + F (Pr) of the equation (8) also becomes smaller as Pr becomes smaller, and the index signal β represented by the equation (8) is the largest at the pressure Pstt at the start of the rise of the pressure measurement value Pr. Become. Further, as can be seen from the equation (14), the value of the index signal β (that is, the maximum value of the index signal β) when Pr = Pstt increases as the value of Pstt decreases, and Pstt on the right side of the equation (14). The value Se0 / V when = 0 is the upper limit of the index signal β.

On the other hand, when the measured pressure value Pr starts to rise from the starting pressure Pstt and almost reaches (Se0 / Se_fix) × Ps, F (Pr) represented by the equation (10) is F (Pr) → It becomes + ∞. When F (Pr) is used, the index signal β is expressed as β = (Se_fix / V) / [1 + F (Pr)], so that the index signal β converges to +0 as in β → +0. As described above, it can be seen that the index signal β monotonically decreases to a zero value with Se0 / V as the upper limit when “it does not exceed at all” in the up case.

FIG. 9 is a diagram showing changes in pressure (pressure measurement value Pr and predicted pressure Pp), index signal β, and opening degree setting θ1 when the opening degree setting θ1 is fixed to the value θ1_fix. Even after the opening degree setting θ1 is fixed to θ1_fix, the measured pressure value Pr and the predicted pressure Pp continue to increase, and if they continue for a sufficiently long time, they both converge to the pressure equilibrium value Pe (θ1_fix) at the opening degree θ1_fix. The calculated index signal β monotonically decreases to a zero value with Se0 / V as the upper limit. Therefore, by detecting that the index signal β is monotonically decreasing, it can be determined that the opening degree setting θ1 = θ1_fix is “not exceeded at all”.

[2. When "does not exceed at all" in the down case]
Next, the response process from the pressure Pstt at the starting point to (Se0 / Se_fix) × Ps when the pressure measurement value Pr “does not exceed at all” in the down case is examined. As described below, it can be seen that in this case as well, as in the case of "not exceeding at all" in the up case, the value monotonically decreases to the zero value with (Se_fix / V) as the upper limit.

The pressure measurement value Pr during the pressure drop satisfies the relationship of Ps <Pe (θ1_1) ≤ Pe (θse) <Pr <Pstt. As described above, θ1_1 is collectively expressed as θ1_fix, so Ps <Pe (θ1_1) <Pr in the above pressure relationship and Pe (θ1_fix) = (Se0 / Se_fix) × Ps in the equation (4). From, the relation of the following equation (15) is obtained.
Ps <(Se0 / Se_fix) x Ps <Pr ... (15)

From equation (15), {(Se0 / Se_fix) × Ps-Pr} <0, {(Se0 / Se_fix) × Ps-Ps}> 0, so F (Pr) represented by the above equation (10) is F (Pr)> 0. Therefore, the denominator on the right side of the equation (8) is a positive value, and the index signal β is always positive even if the pressure measurement value Pr changes with time.

In the case of a down case where the pressure drops from the pressure Pstt at the starting point of control, the pressure measurement value Pr is Pr <Pstt, so − {(Se0 / Se_fix) × Ps-Pstt} ＞ − {(Se0 / Se_fix) × From the relationship of Ps-Pr}> 0, the above equation (11) holds in the same manner.
{(Se0 / Se_fix) x Ps-Pr} / {(Se0 / Se_fix) x Ps-Pstt} <1 ... (11)
Regarding the magnitude relationship between F (Pr) of equation (10) multiplied by the left side of equation (11) and F (Pr), the above-mentioned equation (12) holds in the same manner.
F (Pr)>-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}
… (12)

Therefore, the equations (13) and (14) hold as in the case of "not exceeding at all" in the above-mentioned up case.
1 / (Right side denominator) <1 / [1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}]
… (13)
β <(Se_fix / V) / [1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}]
… (14)

In the down case, the pressure measurement value Pr in the equation (8) of the index signal β descends from the pressure Pstt at the starting point toward (Se0 / Se_fix) × Ps (> Ps) corresponding to the opening degree θ1_fix. In the down case, {(Se0 / Se_fix) × Ps-Pr} in the equation (8) becomes negative, and its absolute value becomes smaller as the pressure measurement value Pr approaches (Se0 / Se_fix) × Ps. That is, the denominator on the right side of the equation (8) becomes larger as the measured pressure value Pr approaches (Se0 / Se_fix) × Ps, and conversely, the index signal β becomes smaller. In other words, the index signal β becomes the largest at the pressure Pstt at the start of the descent of the pressure measurement value Pr. Therefore, even in the down case, the value Se0 / V when Pstt = 0 on the right side of the equation (14) is the upper limit value of the index signal β.

On the other hand, when the measured pressure value Pr starts to descend from the starting pressure Pstt and almost reaches (Se0 / Se_fix) × Ps, F (Pr) represented by the equation (10) is F (Pr) → It becomes + ∞. When F (Pr) is used, the index signal β is expressed as β = (Se_fix / V) / [1 + F (Pr)], so that the index signal β converges to +0 as in β → +0. After all, it can be seen that the index signal β monotonically decreases to a zero value with Se0 / V as the upper limit even when “it does not exceed at all” in the down case.

[3. When "exceeding" in the up case]
In the case of "exceeding" in the up case, as shown in FIG. 7, the relationship of Pstt <Pr <Ps <Pe (θse) ≤ Pe (θ1_1) is satisfied. Since Pr <Ps <Pe (θ1_1), considering that Pe (θ1_1) = Pe (θ1_fix) = (Se0 / Se_fix) × Ps, in equation (8), {(Se0 / Se_fix) × Ps-Pr }> 0, {(Se0 / Se_fix) × Ps-Ps}> 0. Since Pr <Ps, the following equation (16) holds.
0 <{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pr} = -F (Pr) <1
… (16)

From the magnitude relationship on the right side of equation (16), the right-hand side denominator = 1 + F (Pr) is a positive value in equation (8), and the index signal β is always a positive value. In the case of the up case, the equation (11) holds as described above.
{(Se0 / Se_fix) x Ps-Pr} / {(Se0 / Se_fix) x Ps-Pstt} <1 ... (11)
By multiplying both sides of the equation (11) by F (Pr), which is a negative value, the following equation (17) is obtained.
-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}> F (Pr)
… (17)

Equation (17) is transformed as in equation (18).
1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}> 1 + F (Pr)
1 / [1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}]
<1 / {1 + F (Pr)} ... (18)
Multiplying both sides of the equation (18) by a positive value (Se_fix / V) gives the following equation (19).
(Se_fix / V) / [1-{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pstt}] <β
… (19)

In the up case, the pressure measurement value Pr in the equation (8) of the index signal β rises from the pressure Pstt at the starting point. {(Se0 / Se_fix) × Ps-Ps} / {(Se0 / Se_fix) × Ps-Pr} in the right-hand side denominator of equation (8) takes a value from 0 to 1 as shown in equation (16), and Pr The smaller the value, that is, the farther Pr is from (Se0 / Se_fix) × Ps, the smaller the value becomes. Therefore, the smaller Pr, the larger the right-side denominator of Eq. (8), and conversely, the smaller the index signal β. Therefore, the index signal β becomes the smallest at the pressure Pstt at the start of the rise of the pressure measurement value Pr. Further, as can be seen from the equation (19), the value of the index signal β (that is, the minimum value of the index signal β) when Pr = Pstt becomes smaller as the value of Pstt becomes smaller, and Pstt on the right side of the equation (19). The value Se0 / V when = 0 is the lower limit of the index signal β.

In addition, when the pressure measurement value Pr starts to rise from the starting pressure Pstt and almost reaches Ps, the right-hand side denominator of equation (8) approaches zero with a positive value such as (right-hand side denominator) → +0. At that time, the index signal β becomes β → + ∞. That is, it can be seen that the index signal β increases monotonically with Se0 / V as the lower limit when it “exceeds” in the up case.

[4. When "exceeding" in the down case]
In the case of “exceeding” in the down case, as shown in FIG. 7, the relationship of Pe (θ1_1) ≦ Pe (θse) <Ps <Pr <Pstt is satisfied. Since Pe (θ1_1) <Ps <Pr, in equation (8), {(Se0 / Se_fix) × Ps-Pr} <0, {(Se0 / Se_fix) × Ps-Ps} <0. Since Ps <Pr, the above equation (16) holds, the right side denominator of the equation (8) has a positive value, and the index signal β always has a positive value.
0 <{(Se0 / Se_fix) x Ps-Ps} / {(Se0 / Se_fix) x Ps-Pr} = -F (Pr) <1
… (16)

When "exceeding" in the down case, the equation (11) holds as in the case of "not exceeding" in the down case.
{(Se0 / Se_fix) x Ps-Pr} / {(Se0 / Se_fix) x Ps-Pstt} <1 ... (11)
Equations (17) to (19) are obtained with respect to equation (11), as in the case of “exceeding” in the up case.

In the down case, the pressure measurement value Pr in the equation (8) of the index signal β drops from the pressure Pstt at the starting point. {(Se0 / Se_fix) × Ps-Ps} / {(Se0 / Se_fix) × Ps-Pr} in the right-hand side denominator of equation (8) takes a value from 0 to 1 as shown in equation (16). The smaller Pr, that is, the closer Pr approaches (Se0 / Se_fix) × Ps, the larger the value becomes. Therefore, as Pr approaches (Se0 / Se_fix) × Ps, the denominator on the right side of the equation (8) becomes smaller, and conversely, the index signal β becomes larger. Therefore, the index signal β is the smallest when the measured pressure value Pr is the pressure Pstt farthest from (Se0 / Se_fix) × Ps. Further, as can be seen from the equation (19), the value of the index signal β (that is, the minimum value of the index signal β) when Pr = Pstt becomes smaller as the value of Pstt becomes smaller, and Pstt on the right side of the equation (19). The value Se0 / V when = 0 is the lower limit of the index signal β.

In addition, when the measured pressure value Pr starts to descend from the starting pressure Pstt and almost reaches Ps, the right-hand side denominator of Eq. (8) approaches zero with a positive value such as (right-hand side denominator) → +0. At that time, the index signal β becomes β → + ∞. That is, it can be seen that the index signal β increases monotonically with Se0 / V as the lower limit when it “exceeds” in the down case.

FIG. 10 summarizes the results of the cases of “exceeding” and “not exceeding” in the up case and the down case described above.

(Timing of generation of index signal β)
An example of the generation timing of the index signal β in the estimation calculation unit 210 of FIG. 2 will be described. The pressure target value Ps, the pressure measurement value Pr, and the opening degree measurement value θr are input to the estimation calculation unit 210. The estimation calculation unit 210 obtains the pressure differential amount (dPr / dt) of the equation (1) by calculating ΔPr / Δt from the difference ΔPr of the pressure measurement value Pr between appropriate control cycles Δt (for example, 10 ms). , The index signal β is calculated based on the pressure differential amount and the input pressure target value Ps and pressure measurement value Pr.

As described above, since the index signal β does not use any parameters other than the pressure target value Ps and the pressure measurement value Pr, it can be applied even if the gas type and gas flow rate of the gas introduced into the vacuum chamber 3 are unknown. In other words, a highly reliable index signal β can be obtained even if the gas type and gas flow rate are unknown.

As the generation timing of the index signal β, whether the index signal β monotonically increases or decreases with the passage of time in a state where the open control opening setting θ1 is fixed, that is, when θ1_fix is set. You just have to judge. For example, when the control cycle is 10 ms, the index signal β is calculated a plurality of times every 10 ms so as to be calculated 10 to 40 times in a period of 100 ms to 400 ms. Then, when the index signal β calculated multiple times tends to increase continuously (previous value <current value), it is determined to "exceed" and continuously decrease (previous value> this time). If there is a tendency of (value), it is judged that "it does not exceed at all".

(Control processing based on predicted pressure Pp and index signal β)
FIG. 11 is a flowchart showing an example of the control process performed by the pressure regulating controller 21 when the predicted pressure Pp and the index signal β are used in combination. FIG. 11 shows a determination process using the predicted pressure Pp and the index signal β, and an opening degree control process after the determination. Further, FIG. 12 is a diagram showing changes in the pressure measurement value Pr, the index signal β, and the opening degree setting θ1 in the up case. In the determination using the predicted pressure Pp and the index signal β described below in combination, the predicted pressure Pp determines the case of “exceeding”, and the index signal β determines the case of “not exceeding at all”.

When the pressure target value Ps is input to the pressure regulating controller 21, the target opening degree estimated value θse is calculated by the estimation calculation unit 210 based on the pressure target value Ps, and the opening degree is set from the feed forward controller 220 based on the calculation. θ1_fix is output. The opening degree setting θ1_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 θ1_fix.

In step S10 of FIG. 11, it is determined whether or not the opening degree measurement value θr becomes the value of the opening degree setting θ1_fix output from the feedforward controller 220. If it is determined in step S10 that θr = θ1_fix, the process proceeds to step S20. In step S20, the estimation calculation unit 210 calculates the index signal β. In step S30, m indicating the number of times β (previous)> β (this time) was determined in step S70, which will be described later, is set to m = 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 it is determined that Pp> Ps, the process proceeds to step S100 to execute the opening degree change process. The opening degree changing process in step S100 will be described later. On the other hand, if it is determined that Pp> Ps is not satisfied, the process proceeds to step S60. In step S60, the index signal β is calculated.

In step S70, it is determined whether or not the predicted pressure Pp “does not exceed the pressure target value Ps” at all. Specifically, the index signal β (previous) calculated in step S20 and the index signal β (this time) calculated in step S60 are compared, and it is determined whether β (previous)> β (this time). .. As shown in FIG. 10, in both the up case and the down case, the index signal β decreases monotonically when “it does not exceed at all”, and the index signal β is the judgment condition “β (previous)> β (this time). Satisfy. If it is determined in step S70 that β (previous)> β (this time), the process proceeds to step S80, and if it is determined that β (previous)> β (this time) is not satisfied, the process returns to step S30.

For example, in the case of the up case shown in FIG. 12, the index signal β (previous time) and the index signal β (current time) are calculated in a predetermined period including the time t1 in a state fixed at θ1 = θse (= θ1_fix). The calculated index signal β (previous) and index signal β (this time) satisfy β (previous)> β (this time). Therefore, it is determined as yes in step S70, 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 of times m determined as β (previous)> β (this time) has reached the upper limit value N, and if it is reached (m = N), the process proceeds to step S100. If it has not reached (m <N), the process returns to step S40, and the processes from step S40 to step S90 are repeatedly executed until m = N. The upper limit value N is a natural number. In the above-mentioned example of the generation timing of the index signal β, N = 10 to 40, but the present invention is not limited to this, and may be, for example, the minimum one.

That is, when the fixed opening degree θ1_fix is the opening degree setting in the situation where the predicted pressure Pp “does not exceed the pressure target value Ps at all”, the processes from step S40 to step S90 are repeatedly executed, and step S90. At the time when m = N is determined (time t2 in FIG. 12), the opening degree change process in step S100 is executed. On the other hand, when the fixed opening degree θ1_fix is the opening degree setting in which the predicted pressure Pp “exceeds” the pressure target value Ps, the processes from step S30 to step S80 are repeatedly executed, and finally. In step S50, it is determined that Pp> Ps, and the opening degree change process in step S100 is executed.

(Opening change processing)
In the opening change processing, the estimation calculation unit 210 in FIG. 2 recalculates the opening target estimated value (here, the value is expressed as θse2), and the opening setting θ1 output from the feedforward controller 220 is set to θ1. = Set to θse2. For example, in FIG. 12 in the case of “not exceeding at all” in the up case, the opening degree setting θ1 is changed to θse2 at time t2, and the pressure response of the pressure measurement value Pr which has been changed as shown by the line L1 until then is The pressure response changes as shown by line L2. Further, when it is determined to "exceed" in step S50 and the process proceeds to step S100, the pressure response and the like as shown in FIG. 12 are not shown, but the opening target estimated value θse2 obtained by recalculation is θse2. > Θse.

In step S110, it is determined whether or not the condition for shifting from the open control to the closed control is satisfied, and if the condition is satisfied, the open control is terminated and the control is shifted to the closed control. The transition conditions include, for example, when the pressure measurement value Pr is sufficiently close to the pressure target value Ps, such as when the difference between Pr and Ps is 5% or less of the magnitude of Ps, or when the index signal β decreases monotonically. It is conceivable that the increase will be monotonous.

When the open control is switched to the closed control at the time t3 of FIG. 12, a constant opening degree setting θse2 is output from the feedforward controller 220, and an opening degree setting θ2 is output from the feedback controller 230. After the start of the close control, the pressure response of the pressure measurement value Pr changes as in the line L3, and at time t4, the pressure measurement value Pr substantially converges to the pressure target value Ps.

The opening degree θs is an opening degree at which the pressure equilibrium value becomes the pressure target value Ps, but when the opening degree setting θ1 (= θse) is θ1≈θs with respect to this opening degree θs, it “exceeds”. And "do not exceed at all" may not be judged. In such a case, for example, when the index signal β is calculated N_timeout times after being fixed at the opening setting θ1, that is, when the calculation cycle is Δt (for example, 10 ms described above), the time N_timeout × When Δt has elapsed, the open control may be shifted to the closed control. However, N_timeout> N.

FIG. 13 is a diagram showing a comparative example, and shows a case where the predicted pressure Pp is used as an index for determination when “it does not exceed at all”. Using the predicted pressure Pp, the determination that the fixed opening is finally Pp <Ps is determined until the predicted pressure Pp sufficiently converges to the pressure equilibrium value (time t11 in FIG. 13). do not do. Therefore, the response of the pressure measurement value Pr stalls during that time, and the pressure adjustment time for bringing the pressure measurement value Pr closer to the pressure target value Ps after shifting to the close control at time t11 becomes long.

On the other hand, when the index signal β is used, it can be determined that the pressure measurement value Pr “does not exceed at all” at an early stage in the ascending process as shown at time t2 in FIG. Therefore, the time from fixing the opening degree setting θ1 to θse until the pressure measurement value Pr converges to the pressure target value Ps can be shortened as compared with the case where the predicted pressure Pp is used. Although the figure of the predicted pressure Pp is omitted in FIG. 12, the predicted pressure Pp is also in the process of increasing at time t2.

(Calculation method of opening target estimated value θse)
An example of the calculation method of the opening target estimated value θse will be described. Here, a calculation method for obtaining the opening target estimated value θse by using the plant gain Gp, which is the correlation between the opening degree θ and the pressure P, will be described. The plant gain Gp is defined by the following equation (20). Note that | (ΔP / Δθ) | indicates the absolute value of (ΔP / Δθ).
Gp = | (ΔP / Δθ) | / P… (20)

As can be seen from the equation (20), when the opening degree θ is input and the pressure P of the vacuum chamber 3 is used as the output, the pressure change with respect to the opening degree change, that is, (ΔP / Δθ) is standardized by the pressure P ((ΔP). / Δθ) / P) represents the static gain characteristic of the pressure response of the lean gas in the vacuum chamber 3 which is the plant. The plant gain Gp (θ) is stored in the storage unit 23 of FIG. 1 as, for example, a data table (θ, Gp) showing the relationship between the opening degree θ and the plant gain Gp.

When the pressure adjustment state that is the equilibrium state is expressed as (θ, P), the pressure adjustment state before the opening change is expressed as (θse, Pr), and the target pressure adjustment state is expressed as (θse2, Ps). Will be done. Using the definition formula of the formula (20), the relationship between the opening degree change Δθ and the pressure change ΔP is expressed as the formula (21).
ΔP = −P × Gp (θ) × Δθ… (21)

The relationship between the pressure regulation state (θse, Pr) and the pressure regulation state (θse2, Ps) can be expressed by the following equations (22) and (23).
θse2 ＝ θse ＋ ∫dθ (Integration range is from θse to θse2)… (22)
Ps = Pr + ∫dP (Integration range is from Pr to Ps)… (23)

The integrals of equations (22) and (23) are actually the increment Δθ of the opening degree and the increment ΔP of the pressure in each quasi-static state from the pressure regulation state (θse, Pr) to the pressure regulation state (θse2, Ps). Are expressed as the sum of each, so θse2 and Ps can be expressed as the following equations (24) and (25). Note that Δθ_n (θ_n) in the equation (24) indicates that the opening degree increment Δθ_n at the opening degree θ_n. For example, Δθ_1 (θ_1) is the opening degree when the opening degree θse changes to the opening degree θ_1. It is an increment. Similarly, ΔP_n (p_n) represents the pressure increment at pressure P_n.
θse2 ＝ θse ＋ ΣΔθ_n (θ_n)… (24)
Ps = Pr + ΣΔP_n (P_n)… (25)

Regarding Δθ_n (θ_n) of the equation (24), the increment Δθ_n (θ_n) may be given according to each opening degree θ_n as in the equation (26). Regarding ΔP_n (P_n) of the equation (25), the increment ΔP_n (P_n) at the pressure P_n corresponding to the increment Δθ_n (θ_n) at the opening θ_n may be given by using the correlation between the opening θ and the pressure P. When the plant gain Gp is used as the correlation, the increment ΔP_n = ΔP_n (P_n) at the pressure P_n is expressed as the following equation (27) by applying the above equation (21). In the equation (27), Δθ_n = Δθ_n (θ_n) and Gp_n = Gp (θ_n).
Δθ_n ＝ Δθ_n (θ_n)… (26)
ΔP_n ＝ ΔP_n (P_n) ＝ −P_n × Gp_n × Δθ_n… (27)

By substituting the equations (26) and (27) into the equations (24) and (25) and performing the cumulative calculation, the opening value θse2 and the pressure target value Ps in the pressure adjustment state (θse2, Ps) can be roughly reached. Further, if the equations (24) and (25) are modified and expressed as follows, the sequential calculation can be performed.
θ_n + 1 = θ_n + Δθ_n… (28)
P_n + 1 = P_n + ΔP_n… (29)

The opening degree θ is cumulatively calculated from the equations (26) and (28), and the pressure P is sequentially calculated from the equations (27) and (29). Then, if the value "P0 + ΣΔP_n (P_n)" on the right side of the equation (25), which is the cumulative pressure value, reaches (or exceeds) the next pressure value (here, the pressure target value Ps), the calculation is performed. To finish. The cumulatively calculated opening degree when the pressure target value Ps is reached corresponds to the target opening degree estimated value θse2. It should be noted that the application of this method is useful for obtaining the target opening degree estimation value because a practical approximate value can be obtained even in a state that cannot be said to be a quasi-static state.

(Modification example 1)
FIG. 14 is a flowchart for explaining a modification 1 of the above-described embodiment. In the above-described embodiment, even in the case of "not exceeding at all", the opening degree is changed only once in the opening degree changing process, and then the closing control is started. However, due to a calculation error, the target opening degree estimated value θse and the pressure target value Ps may deviate from each other, and the pressure measurement value Pr may not be brought close to the pressure target value Ps by changing the opening degree once. Therefore, in the control process shown in the flowchart of FIG. 14, step S200 is added to the flowchart shown in FIG. 11 so that the opening degree is changed based on the index signal β up to a predetermined upper limit number of times.

In the up case shown in FIG. 15, the determination by the index signal β is performed twice, and the opening degree setting θ1 is changed to θse2 and θse3. In this case, the target opening degree estimated value θse2 calculated after the first determination is larger than the target opening degree θs, and the index signal β is monotonically decreased even after the change. The target opening degree estimated value θse3 calculated after the second determination is smaller than the target opening degree θs, and the changed index signal β has turned to a monotonous increase. Therefore, in step S110 of FIG. 14, it is determined that the transition condition (β monotonically decreases → monotonically increases) is satisfied, and the open control is shifted to the closed control. For example, when the upper limit of the number of times in step S200 is 2 and θse3> θs in FIG. 15, it is determined as yes in step S200 before it is determined as yes in step S110, and the open control is changed to the closed control. It will be migrated.

(Modification 2)
In the flowchart of FIG. 11 in which the predicted pressure Pp and the index signal β are used in combination, the predicted pressure Pp is used for the determination of “exceeding” as in step S50. However, even in the case of "exceeding", the index signal β may be used for determination. When the index signal β is used to determine “exceed”, as can be seen from FIG. 10, when the index signal β is monotonically increasing, it is determined to “exceed”. In that case, the flowchart of FIG. 11 is changed as shown in FIG. 16 in the second modification.

If it is determined in step S10 of FIG. 16 that the value of the opening measurement value θr has reached the opening setting θ1_fix and the index signal β is calculated in step S20, m1 = 0 and m2 = 0 are set in step S300. .. If the index signal β is calculated in the following step S310, it is determined in step S320 whether or not the predicted pressure Pp “does not exceed the pressure target value Ps”, that is, whether β (previous)> β (this time). Is judged. If β (previous)> β (this time) is determined in step S320, the process proceeds to step S330 to increase m1 = m1 + 1 and m1 by one. In step S340, it is determined whether or not m1 representing the number of times β (previous)> β (this time) has been determined has reached the upper limit value N1, and if it has reached (m1 = N1), the process proceeds to step S100. 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 (this time)" is not satisfied, the process proceeds to step S322 to set m1 = 0, and then in step S324 whether or not to "exceed", that is, " It is determined whether or not β (previous) <β (this time) ”. If it is determined in step S324 that "β (previous) <β (this time)", the process proceeds to step S326 to increase m2 = m2 + 1 and m2 by 1, and then proceeds to step S328. On the other hand, if it is determined in step S324 that "β (previous) <β (this time)" is not satisfied, the process proceeds to step S325 to set m2 = 0, and then returns to step S310. In step S328, it is determined whether or not m2, which represents the number of times β (previous) <β (this time), has reached the upper limit value N2, and if it reaches (m2 = N2), the process proceeds to step S100. If it has not reached (m2 <N2), the process returns to step S310.

As described above, when the process from step S310 to step S340 is repeated and the number of times that "β (previous)> β (this time)" is determined reaches the upper limit value N1, or from step S310 to step S328. When the number of times that "β (previous) <β (this time)" is determined by repeating the above process reaches the upper limit value N2, the opening degree changing process is performed in step S100. Then, in step S110, it is determined whether or not the transition condition from the open control to the closed control is satisfied, and if the condition is satisfied, the open control is terminated and the transition to the closed control is performed.

As described above, the predicted pressure Pp is a pressure estimated value t seconds after the time when the measured pressure value Pr is measured, and depends on the effective exhaust velocity Se based on the reference gas and the estimated value of the flow rate Qin. Since the gas type of the reference gas is generally different from the gas type of the gas actually flowing, the error of the predicted pressure Pp may become large.

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

(Modification 3)
In the above-described embodiments and modifications 1 and 2, both cases of "exceeding" and "not exceeding" have been described as examples. However, if the opening change amount in the open control is not large enough to change from the 4th quadrant to the 3rd quadrant in FIG. 4, the flowchart corresponding only to the case of “not exceeding at all” as shown in FIG. You may adopt it. The flowchart shown in FIG. 17 is obtained by deleting the processes of steps S40 and S50 from the flowchart shown in FIG. When the process from step S30 to step S90 is repeated N times and it is determined that "it does not exceed at all", the opening degree change process of step S100 is performed.

As in the case of the flowchart of FIG. 14, in consideration of the case where the pressure measurement value Pr cannot be brought to the vicinity of the pressure target value Ps by one opening change, the index signal β is set as in step S200. The opening is changed up to a predetermined upper limit. Further, when the opening setting θ1 (= θse) is θ1 ≈ θs and it is not determined that “it does not exceed at all”, the index signal β is calculated N_timeout times after being fixed to the opening setting θ1. Make a transition from open control to closed control.

(Modification example 4)
In the first embodiment described above, the index signal β (= (dPr / dt) / (Ps-Pr)) defined by the equation (1) was introduced as an index signal instead of the predicted pressure Pp. However, as the index signal instead of the predicted pressure Pp, not only the signal defined by the equation (1) but also various similar signals as described below can be applied.

・ Indicator signal β1 standardized to dimensionless quantity
The index signal β1 defined by the following equation (30) is introduced from the volume V of the vacuum chamber 3 and the data set Se_r (θr) representing the correlation between the effective exhaust velocity Se and the opening measurement value θr. By standardizing to a dimensionless quantity, the versatility of the determination threshold value can be further improved even when conditions such as the gas flow rate value are changed.
β1 = (V / Se_r (θr)) × [(dPr / dt) / (Ps−Pr)]… (30)

・ Indicator signal β2 that is surely a positive value
In principle, "(dPr / dt) / (Ps-Pr)" is judged within the range of positive values regardless of the up case or down case. However, in preparation for disturbances such as sudden changes in flow rate, the index signal β2, which is surely a positive value, can be obtained by using an absolute value signal for both the denominator and the numerator as shown in equations (31) and (32). ..
β2 ＝ | dPr / dt | / | Ps-Pr |… (31)
Or
β2 = (V / Se_r (θr)) × | dPr / dt | / | Ps-Pr |… (32)

It will be understood by those skilled in the art that the plurality of exemplary embodiments and modifications described above are specific examples of the following embodiments.

[1] The valve control device according to one aspect is an opening setting unit that outputs an open control opening setting value in a valve control device that controls the opening of a vacuum valve mounted in a vacuum chamber by open control. The first determination unit for determining that the pressure equilibrium value in the case of the constant value does not exceed the pressure target value of the valve control in a predetermined period within the fixed period in which the opening setting value becomes a constant value, and the above. It includes 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, based on the index signal β (previous) and the index signal β (current time) calculated in a predetermined period including the time t1 of the period in which the opening setting value θ1 is a constant value θ1_fix. It is determined that the pressure equilibrium value Pe (θ1_fix) does not exceed the pressure target value Ps. Therefore, it can be determined that the predicted pressure Pp and the measured pressure value Pr do not exceed the pressure equilibrium value that does not exceed the pressure target value Ps at an early stage without waiting for the pressure equilibrium value to be converged. By performing the control, the pressure adjustment time can be shortened.

[2] In the valve control device according to the above [1], the pressure equilibrium value exceeds the pressure target value, or the predicted pressure of the vacuum chamber after the elapse of the predicted time based on the constant value is the pressure target. A second determination unit for determining that the value is exceeded is further provided, and the opening degree control unit controls the opening degree based on the determination results of the first and second determination units.

For example, as shown in FIG. 12, based on the index signal β (previous) and the index signal β (current time) calculated in a predetermined period including the time t1 of the period in which the opening setting value θ1 is a constant value θ1_fix. It is determined that the pressure equilibrium value Pe (θ1_fix) does not exceed the pressure target value Ps. Further, as in step S324 of FIG. 16, it is determined that the pressure equilibrium value Pe (θ1_fix) exceeds the pressure target value Ps based on the index signal β (previous time) and the index signal β (current time) in the above-mentioned predetermined period. Or, it is determined that the predicted pressure Pp exceeds the pressure target value Ps when the predicted pressure Pp becomes Pp> Ps as in step S50 of FIG.

Therefore, it can be determined that the predicted pressure Pp and the measured pressure value Pr do not exceed the pressure target value Ps at an early stage without waiting for the pressure equilibrium value to converge, and based on the determination result. By further controlling the opening degree, the pressure adjustment time can be shortened.

[3] In the valve control device according to the above [2], the first determination unit is based on the ratio of the time change rate of the pressure measurement value to the pressure measurement value and the difference value of the pressure target value. It is determined that the pressure equilibrium value does not exceed the pressure target value, and the second determination unit determines that the pressure equilibrium value exceeds the pressure target value based on the ratio.

The index signal β defined by the equation (1) is the ratio of the time change rate (dPr / dt) of the pressure measurement value Pr to the difference value (Ps-Pr) of the pressure measurement value Pr and the pressure target value Ps. There is. With such an amount, the ratio (that is, the index signal β) monotonically increases when it “exceeds” and decreases monotonically when it “does not exceed at all”. Therefore, by investigating whether the ratio increases monotonically or decreases monotonically during the predetermined period within the fixed period described above, even if the pressure measurement value Pr does not converge to the pressure target value Ps in the predetermined period, it does not exceed it. Can be determined.

In equation (1), it is defined as (dPr / dt) / (Ps-Pr), but even if the index signal has the denominator and numerator reversed, the case where it exceeds is monotonically decreased and the case where it does not exceed is monotonically increased. Therefore, it is possible to determine whether or not the signal is exceeded by examining whether the signal is monotonically increasing or monotonously decreasing.

[4] In the valve control device according to the above [3], the ratio is "(dPr / dt) 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). It is set as "dPr / dt) / (Ps-Pr)". By setting the ratio in this way, it is possible to determine whether the ratio does not exceed the monotonous increase or the monotonous decrease in the predetermined period within the fixed period described above.

[5] In the valve control device according to any one of the above [2] to [4], the pressure target value corresponds to the opening degree set value and the pressure measured value in the opening degree set value. An estimation unit for estimating a target opening degree estimated value is provided, and the opening degree control unit controls the opening degree to the target opening degree estimated value based on the determination results of the first and second determination units.

For example, when it is determined that Pp> Ps in step S50 as in the process shown in FIG. 11, or as in steps S70 and S90, the determination of “β (previous)> β (this time)” continues N times. In this case, the opening degree setting θ1 is set to the target opening degree estimated value θse 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 estimated value θse. As a result, the measured pressure value Pr can be brought closer to the pressure target value Ps.

[6] The vacuum valve according to one aspect is described in the above [1], wherein the valve body, the valve body driving unit for driving the valve body, and the valve body driving unit are controlled to control the opening degree of the valve body. The valve control device according to any one of up to [5] is provided. As a result, the pressure adjusting time by the vacuum valve can be further shortened.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included within the scope of the present invention.

1 ... Valve body, 2 ... Valve control device, 3 ... Vacuum chamber, 4 ... Vacuum pump, 12 ... Valve body, 13 ... Motor, 21 ... Pressure control controller, 22 ... Motor drive unit, 23 ... Storage unit, 210 ... Estimating calculation unit, 220 ... Feed forward controller, 230 ... Feedback controller, Pp ... Predicted pressure, Pr ... Pressure measurement value, Ps ... Pressure target value, θ1, θ2, θset ... Opening setting, θr ... Opening measurement value , Θse… Estimated target opening, β, β1, β2… Indicator signal

Claims (6)

In a valve control device that controls the opening degree of a vacuum valve mounted in a vacuum chamber by open control.
An opening setting unit that outputs the opening control opening setting value and
A first determination unit that determines that the pressure equilibrium value in the case of the constant value does not exceed the pressure target value of the valve control in a predetermined period within the fixed period in which the opening setting value becomes a constant value.
A valve control device including an opening degree control unit that controls the opening degree based on a determination result of the first determination unit. In the valve control device according to claim 1,
A second determination unit for determining that the pressure equilibrium value exceeds the pressure target value or that the predicted pressure of the vacuum chamber after the elapse of the predicted time based on the constant value exceeds the pressure target value is further provided. ,
The opening degree control unit is a valve control device that controls the opening degree based on the determination results of the first and second determination units. In the valve control device according to claim 2,
The first determination unit determines that the pressure equilibrium value does not exceed the pressure target value based on the ratio of the time change rate of the pressure measurement value to the pressure measurement value and the difference value of the pressure target value. ,
The second determination unit is a valve control device that determines that the pressure equilibrium value exceeds the pressure target value based on the ratio. In the valve control device according to claim 3,
The ratio is set as "(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). The valve control device. The valve control device according to any one of claims 2 to 4.
It is provided with an estimation unit that estimates a target opening degree estimated value corresponding to a pressure target value based on the opening degree set value and the pressure measurement value in the opening degree set value.
The opening degree control unit is a valve control device that controls the opening degree to the target opening degree estimated value based on the determination results of the first and second determination units. With the valve body
A valve body driving unit that drives the valve body and
A vacuum valve comprising the valve control device according to any one of claims 1 to 5, which controls the valve body driving unit to control the opening degree of the valve body.

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