CN111750125B - 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) is provided with: a closing control unit (21) that generates an opening degree setting output (delta theta), which is an opening degree control signal that uses closing control, on the basis of a target pressure (Ps); and an opening degree increase generation unit (22) that generates an opening degree increase (Δ θ blob) based on the opening degree (θ r) of the vacuum valve, the pressure (Pr), the target pressure (Ps), and the correlation relationships Se (θ) and Gp (θ) between the opening degree (θ) and the effective exhaust speed (Se), in synchronization with a timing t1 at which the pressure (Pr) of the vacuum chamber (3) reaches the target pressure (Ps), and adds the opening degree increase (Δ θ blob) to the opening degree control signal (Δ θ).

Description

Valve control device and vacuum valve

Technical Field

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

Background

Conventionally, there is known a vacuum valve in which pressure is adjusted by automatically controlling the opening degree of a valve body, and chamber pressure is converged to a target pressure by closing control (for example, see patent document 1). In the closing control, a set opening degree signal is generated based on a pressure deviation between a set pressure and a detected chamber pressure, and the valve body motor is driven so that the valve body opening degree becomes the set opening degree value, whereby feedback control is performed so that the pressure deviation becomes zero.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2018-112933

Disclosure of Invention

[ problems to be solved by the invention ]

In the conventional closing control, feedback control is performed based on a pressure deviation that is a difference between a detected chamber pressure and a target pressure. Therefore, if the target pressure is changed in a state where the chamber pressure converges toward the target pressure, the pressure deviation increases rapidly, and therefore, for example, when the target pressure is changed in a direction to increase, a large overshoot (overshoot) may occur, and the pressure adjustment time may become long.

[ means for solving problems ]

A valve control device according to a preferred embodiment of the present invention controls an opening degree of a vacuum valve provided between a vacuum chamber and a vacuum pump by closing control, and adjusts a chamber pressure of the vacuum chamber to a target pressure, the valve control device including: a signal generation unit that generates an opening degree control signal by closing control based on the target pressure; and an opening degree increase generating unit that generates an opening degree increase signal corresponding to an opening degree difference between the chamber pressure at the timing and the target pressure in synchronization with the timing at which the chamber pressure reaches the predetermined pressure threshold, and adds the opening degree increase signal to the opening degree control signal.

In a more preferred aspect, the opening degree increase generating unit generates the opening degree increase signal based on a correlation between the opening degree of the vacuum valve, the chamber pressure, the target pressure, and the opening degree and an effective exhaust speed of the vacuum chamber.

In a more preferred aspect, the predetermined pressure threshold is set in a predetermined pressure range including the target pressure.

In a more preferred aspect, the predetermined pressure threshold is set to the target pressure.

A vacuum valve according to a preferred embodiment of the present invention includes: a valve body; a valve body driving unit that drives the valve body to open and close; and a valve control device for controlling the opening and closing drive of the valve drive unit.

[ Effect of the invention ]

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

Drawings

Fig. 1 is a block diagram schematically showing the structure of a vacuum apparatus.

Fig. 2 is a plan view showing the suction port side of the vacuum valve.

Fig. 3 is a block diagram showing the structure of the valve control device.

Fig. 4(a) and 4(b) are diagrams illustrating comparative examples.

Fig. 5 is a flowchart showing an example of the opening degree adjusting operation.

Fig. 6 is a diagram showing an example of the body gain.

Fig. 7 is a graph showing a relationship between the pressure Pr and the predicted pressure Pp 04.

Fig. 8(a) and 8(b) are diagrams showing the pressure response and the opening θ r according to the present embodiment.

[ description of symbols ]

1: vacuum valve

2: valve control device

3: vacuum chamber

4: vacuum pump

11: valve plate

12: valve motor

14: encoder for encoding a video signal

21: closing control part

22: opening degree increment generating part

23: motor controller

31: vacuum gauge

32: flow controller

100: vacuum device

210: set pressure generating part

211: feedback controller

Ps: target pressure

Δ θ: opening output of feedback controller

θ set: opening degree setting output

Δ θ blob: increment of opening

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Fig. 1 is a diagram for explaining a valve control device according to the present invention, and is a block diagram showing a schematic configuration of a vacuum apparatus 100 including a vacuum valve 1 controlled by a valve control device 2. The vacuum apparatus 100 is a semiconductor manufacturing apparatus such as a Chemical Vapor Deposition (CVD) apparatus, and includes a vacuum chamber 3 for performing a semiconductor processing process. The vacuum chamber 3 is vacuum-exhausted by a vacuum pump 4 attached through a vacuum valve 1. The vacuum chamber 3 is provided with a vacuum gauge 31 for measuring the pressure in the chamber and a flow rate controller 32 for controlling the flow rate Qin of the gas introduced into the vacuum chamber 3. The vacuum valve 1 is controlled by a valve control device 2. The vacuum pump 4 may be a turbo molecular pump, for example.

The vacuum valve 1 includes a valve plate 11 and a valve motor 12 for driving the valve plate 11 to open and close. The valve motor 12 is provided with an encoder 14 for detecting the opening degree of the valve plate 11. A detection signal (hereinafter, simply referred to as an opening θ r) of the encoder 14 and the pressure Pr of the vacuum chamber 3 measured by the vacuum gauge 31 are input to the valve control device 2. The vacuum valve 1 is an automatic pressure regulating valve, and the valve control device 2 controls the opening degree of the vacuum valve 1 based on the input target pressure Ps and the pressure Pr of the vacuum chamber 3 measured by the vacuum gauge 31, thereby regulating the pressure Pr of the vacuum chamber 3 to the target pressure Ps. The target pressure Ps is input to the valve control device 2 from, for example, a controller (not shown) of the vacuum apparatus 100.

Fig. 2 is a view showing the suction port side of the vacuum valve 1. The valve plate 11 is housed in the valve body 13 of the vacuum valve 1, and a suction port flange 132 having an opening 131 is provided on the suction side of the valve body 13. Further, an exhaust port flange (not shown) to which the vacuum pump 4 is attached is provided coaxially with the intake port flange 132 on the exhaust side (the side opposite to the intake side) of the valve body 13. When the valve motor 12 is rotationally driven in the forward and reverse directions to swing the valve plate 11, the valve plate 11 slides in the horizontal direction to perform a valve opening and closing operation. The valve plate 11 is driven to open and close between a position of 0% opening degree facing the entire opening 131 and a position of 100% opening degree retreating from the opening 131.

(valve control device 2)

Fig. 3 is a block diagram showing the structure of the valve control device 2. The valve control device 2 includes a closing control unit 21, an opening degree increase generation unit 22, and a motor controller 23. The shutdown control Unit 21, the opening increment generation Unit 22, and the motor controller 23 may include a Central Processing Unit (CPU), a Field Programmable Gate Array (FPGA), or the like, or may include a circuit or the like. The closing control unit 21 includes a set pressure generating unit 210 and a feedback controller 211. The opening degree increase generating unit 22 includes a computing unit 220 and a storage unit 221.

The set pressure generating unit 210 of the close control unit 21 generates and outputs the set pressure Pset, which is the current target pressure for each control cycle, based on the input target pressure Ps of the vacuum chamber 3. As the set pressure Pset, for example, there is a target pressure Ps described in japanese patent application laid-open No. 2018-112933, but it is not necessarily limited to the target pressure Ps. Hereinafter, the case where Pset is Ps will be described as an example. The pressure deviation ∈ which is the difference between the measured pressure Pr and the set pressure Pset is input to the feedback controller 211. The feedback controller 211 outputs an opening degree setting output Δ θ as an opening degree control signal based on the pressure deviation ∈. Generally, the feedback controller 211 is composed of a Proportional gain and an Integral gain (so-called Proportional Integral (PI) gain).

On the other hand, the calculation unit 220 of the opening degree increase generation unit 22 calculates an opening degree increase Δ θ blob based on the correlation between the opening degree and the effective exhaust speed (the effective exhaust speed Se and the body gain Gp described later) stored in the storage unit 221, the input target pressure Ps, the pressure Pr measured by the vacuum gauge 31, and the opening degree θ r. The calculation method of the opening degree increment Δ θ blob will be described later. The opening degree increase Δ θ bow from the opening degree increase generating unit 22 is added to the opening degree setting output Δ θ from the feedback controller 211, and the added signal is input to the motor controller 23 as an opening degree setting output θ set. As described later, the opening degree increase Δ θ blob is output from the opening degree increase generation unit 22 only under predetermined conditions. The motor controller 23 performs drive control of the valve motor 12 based on the opening degree setting output θ set.

Comparative example

The closing control by the valve control device 2 shown in fig. 3 differs from the conventional closing control in that the opening degree increase Δ θ bow output from the opening degree increase generating unit 22 at a predetermined timing of the closing control is added to the opening degree setting output Δ θ of the feedback controller 211. Fig. 4(a) and 4(b) are diagrams showing, as comparative examples, pressure responses and changes in the opening degree when the opening degree is controlled only by the opening degree setting output Δ θ of the feedback controller 211, as described in the related art. Fig. 4(a) shows the pressure response Pr, and fig. 4(b) shows the opening θ r.

A line L0 indicated by a broken line in fig. 4(a) indicates the target pressure Ps, and the target pressure Ps changes stepwise from 20mTorr to 30mTorr (═ Ps) when t is 0. When the target pressure Ps changes as 20mTorr → 30mTorr when t is 0, the opening θ r shown by a line L2 in fig. 4(b) is reduced by the closing control. The pressure Pr varies as indicated by a line L1, approaches the target pressure Ps as the opening θ r decreases, and becomes equal to Ps when t becomes equal to t 1. The opening θ r (line L2) is turned from just before t1 to increase, and finally becomes θ s. At the time point when t is t1, the pressure Pr (line L1) tends to increase, and gradually converges to the target pressure Ps after exceeding the target pressure Ps. The opening θ s is an opening in an equilibrium state where the pressure Pr converges to the target pressure Ps. Hereinafter, the equilibrium state where the pressure is Ps and the opening degree is θ s is referred to as an equilibrium state (Ps, θ s).

As described above, in the closing control, when the target pressure Ps is greatly changed in a stepwise manner, an overshoot as in the line L1 is likely to occur, and the pressure adjustment time for converging the pressure Pr to the target pressure Ps becomes longer. Therefore, in the present embodiment, the opening degree increase generating unit 22 shown in fig. 3 is provided, and the opening degree increase Δ θ bow and the opening degree setting output Δ θ are added to each other in the regular timing, thereby suppressing the overshoot of the pressure Pr and shortening the pressure regulating time.

(opening degree adjustment operation)

Fig. 5 is a flowchart showing an example of the opening degree adjusting operation according to the present embodiment. In step S10, it is determined whether the target pressure Ps is input, and if the target pressure Ps is input, the routine proceeds to step S11. In step S11, the opening degree adjustment by the close control is started. That is, the set pressure Pset (═ Ps) is output from the set pressure generation unit 210, and an opening degree setting output Δ θ based on the pressure deviation ∈ Pr — Pset is output from the feedback controller 211, and the opening degree setting output Δ θ is input to the motor controller 23 as an opening degree setting output θ set. The motor controller 23 controls the drive of the valve motor 12 based on the opening degree setting output θ set (═ Δ θ).

In step S12, it is determined whether the measured pressure Pr of the vacuum chamber 3 reaches a predetermined threshold value (for example, Ps) around the target pressure. When it is determined that the pressure Pr has reached the threshold value, the process proceeds to step S13. In step S13, the opening degree increase generation unit 22 outputs an opening degree increase Δ θ blob. The opening degree increment Δ θ bow is added to the opening degree setting output Δ θ output from the feedback controller 211, and the motor controller 23 drive-controls the valve motor 12 based on the added opening degree setting output θ set being Δ θ + Δ θ bow. After the opening degree increment Δ θ bow is output 1 time at the timing at which the pressure Pr reaches the threshold value, the opening degree increment Δ θ bow is fixed while maintaining the output Δ θ bow, and the closing control is continued based on the opening degree setting output θ set being Δ θ + Δ θ bow (fixed). In step S14, it is determined whether or not the target pressure Ps has changed, and if the target pressure Ps has changed, the process returns to step S12.

(method of generating opening increment. DELTA. theta.blob)

Hereinafter, a case where the threshold value in step S12 is set to Ps will be described as an example. The pressure Pr of the vacuum chamber 3 is satisfied by an exhaust gas expression represented by the following expression (1). In the formula (1), V is the volume of the vacuum chamber 3, Se is the effective exhaust velocity of the exhaust system including the conductance (conductance) of the vacuum valve 1, and Qin is the flow rate of the gas introduced into the vacuum chamber 3. The information of the effective exhaust speed Se is given as a correlation Se (θ) of the opening θ of the vacuum valve 1 and the effective exhaust speed Se.

V×(dPr/dt)+Se×Pr＝Qin…(1)

When the flow rate Qin is constant and in a pressure equilibrium state (i.e., dPr/dt is equal to 0), the following expression (2) is established for the pressure increase Δ P, the opening degree increase Δ θ, and the effective exhaust velocity increase Δ Se according to the exhaust expression shown in expression (1).

-(ΔP/Δθ)/Pr＝(ΔSe/Δθ)/Se…(2)

Hereinafter, the amount shown in expression (2) is expressed by a function Gp (θ) of the opening θ, and is referred to as body gain. That is, the body gain Gp (θ) is a quantity defined by the following expression (3), and represents a relationship between equilibrium states under a constant flow rate condition. Fig. 6 is a diagram showing an example of the body gain Gp.

Gp(θ)＝(1/Se)·(ΔSe/Δθ)

＝-(ΔP/Δθ)/Pr…(3)

When the closing control of step S11 in fig. 5 is started and the pressure Pr of the vacuum chamber 3 reaches the target pressure Ps (t 1 in fig. 4 (a)), it is considered that the flow rate Qin of the gas introduced into the vacuum chamber 3 has converged to the predetermined flow rate value Qin 0. That is, Qin-Qin 0 is regarded as constant. Since the body gain Gp is a relationship between the equilibrium states, Δ Ps and Δ θ s in expression (3) refer to difference values between the equilibrium state (Ps, θ s) and another equilibrium state (Ps1, θ s1) in the vicinity thereof, and Δ Ps is Ps1-Ps and Δ θ s is θ s1- θ s. Therefore, the following expression (4) is derived from the expression (3).

θs-θs1＝(Ps1-Ps)/(Ps×Gp(θs))…(4)

When t in fig. 4(a) is t1, the pressure Pr reaches the target pressure Ps, but as can be seen from the line L1, the pressure Pr is increasing, and the speed dPr/dt is dPr/dt > 0. When the opening degree when t is t1 is θ s1, the state (Ps, θ s1) when t is t1 is an unbalanced state, that is, θ s1< θ s. When the pressure value at which the pressure Pr of the vacuum chamber 3 converges at the opening θ s1 is Ps1, that is, the pressure Ps1 in the equilibrium state (Ps1, θ s1) is Ps1> Ps.

In the equation (4), since the opening degrees θ s and θ s1 are adjacent values, Gp (θ s) ≈ Gp (θ s1), and the equation (4) is approximately expressed by the following equation (5).

θs-θs1＝(Ps1-Ps)/(Ps×Gp(θs1))…(5)

As described above, the opening θ s1 in the equation (5) is an opening θ r measured at a timing when the pressure Pr of the vacuum chamber 3 is Pr ═ Ps when t in fig. 4(a) is t1, and therefore can be expressed by the measurement value θ r instead of θ s 1. That is, if the opening degree θ s1 of equation (5) is replaced with the opening degree θ r, equation (6) can be rewritten. Equation (6) can be considered as an equation for calculating the difference between the opening degree θ r and the target opening degree θ s at the time point (t — t 1).

θs-θr＝(Ps1-Ps)/(Ps×Gp(θr))…(6)

As described above, the equation (6) is a calculation equation for obtaining the opening degree difference (θ s- θ r) from the target opening degree θ s at the time point t equal to t1, and the opening degree difference (θ s- θ r) can be calculated if the pressure Ps1 in the equilibrium state (Ps1, θ s1) is known. The pressure Ps1 is a balance pressure when the opening θ r is fixed to the opening θ s1 at the time t1, and therefore can be regarded as a predicted pressure after a relatively long time has elapsed from t1 (ideally after an infinite time t ∞). As an example of a method for obtaining such a predicted pressure, there is a method described in paragraphs 0024 of japanese patent laid-open No. 2018-106718. Only the points will be described here.

The above formula (1) of the exhaust gas is used for calculation of the predicted pressure. A general solution of formula (1) is represented by formula (7) below.

[ numerical formula 1]

As a method of calculating the predicted pressure Pp after t seconds with the current base point from the equation (7), for example, the following discretization relational equations (8) and (9) are used. Using equations (8) and (9), a recurrence equation in units of Δ t until t seconds after the current base point is obtained, and the predicted pressure Pp after t seconds is obtained. For example, if k is set to 1 to 99 and 0.4 seconds is set after t seconds, Δ t is set to 4 msec.

+ Cq (k) x { Qin (currently) + A x k x Δ t } … (9)

Wherein,

Cp(k)＝exp{(-Se(k×Δt)/V)×Δt}

Cq(k)＝(1/V)×{1/(-Se(k×Δt)/V)}×(Cp(k)-1)

in order to calculate the predicted pressure Pp after t seconds using the equations (8) and (9), the estimated flow rate value from the present time to t seconds and the effective exhaust gas velocity Se from the present time to t seconds are required. For example, { Qin (current) + a × k × Δ t } in equation (9) represents an estimated value of the flow rate after k × Δ t seconds from the current time, where a is a constant assuming that the flow rate changes as a × k × Δ t.

When t is t1 in fig. 4(a), the flow rate Qin converges to the predetermined flow rate value Qin0 as described above, and Qin is assumed to be constant Qin 0. Therefore, the constant a in the formulae (8) and (9) is 0. Note that although the effective exhaust speed Se (k × Δ t) in equations (8) and (9) depends on the planned opening degree value, the effective exhaust speed Se (θ r) of the opening degree θ r is used in Se (k × Δ t) because the pressure Ps1 is a balanced pressure when the opening degree θ r is fixed to the opening degree θ s1 at the time t 1.

After t seconds, t is preferably ∞, but calculation is difficult, so that it can be said that about 0.4 seconds after the above is a practical value. Hereinafter, a case where the predicted pressure Pp04 after 0.4 second is applied will be described as an example. Fig. 7 is a graph showing a relationship between the pressure Pr and the predicted pressure Pp 04. The line L1 indicating the pressure Pr is the same as the line shown in fig. 4(a), and the line L3 indicates the predicted pressure Pp 04. The predicted pressure Pp04 can be regarded as being substantially equal to the pressure Ps1 in the equilibrium state (Ps1, θ s1) (Ps1 ≈ Pp 04). In this case, formula (6) is represented by formula (10) below.

Δθblow＝θs-θr≒(Pp04-Ps)/(Ps×Gp(θr))…(10)

Equation (10) is an equation representing an opening degree increase (opening degree difference) from the opening degree θ r to the target opening degree θ s, and corresponds to the opening degree increase Δ θ blow. That is, in step S13 of fig. 5, the opening degree increase generation unit 22 outputs the opening degree increase Δ θ blob calculated by equation (10).

The larger the overshoot of the pressure response shown in fig. 4(a), the larger the predicted pressure Pp04 at the timing Pr ═ Ps (t ═ t 1). That is, it means that the convergence pressure Ps1 in a state where the opening θ r is fixed to θ s1 becomes larger as the overshoot becomes larger and the opening θ r of the timing at which Pr is equal to Ps becomes smaller than θ s 1. Therefore, the predicted pressures Pp and Pp04 calculated based on θ s1 are also changed to be large.

Fig. 8 a and 8 b are diagrams showing the pressure response (fig. 8 a) and the opening degree or (fig. 8 b) in the case where the opening degree increase Δ θ blob is output from the opening degree increase generation unit 22. A line L10 in fig. 8(a) shows a pressure response in the present embodiment, and a line L1 indicated by a chain line shows a pressure response similar to the line L1 shown in fig. 4 (a). A line L11 in fig. 8(b) represents the opening θ r in the present embodiment, and a line L2 indicated by a chain line represents the opening θ r similar to the line L2 shown in fig. 4 (b).

When 0< t < t1, the opening degree setting output θ set in fig. 3 is θ set equal to Δ θ as described in fig. 5, and therefore line L11 shown in fig. 8(b) is the same as line L2 shown in fig. 4 (b). Therefore, the shape of the line L10 of fig. 8(a) at 0< t < t1 is the same as the line L1 of fig. 4 (a).

When the pressure Pr reaches the threshold (Ps in this case) when t is t1, in step S13 in fig. 5, the opening degree increase Δ θ blob at the timing when t is t1 is calculated by the opening degree increase generation unit 22 in fig. 3 and is output from the opening degree increase generation unit 22. As a result, the opening degree setting output θ set when t is t1 is Δ set Δ θ + Δ θ blob, and the line L11 increases the opening degree θ r stepwise by Δ θ blob when t is t 1.

When t > t1, Δ θ blob is fixed while maintaining the state of the output Δ θ blob, and the opening setting output θ set is Δ set ═ Δ θ + Δ θ blob (fixed), and as indicated by a line L11, closing control is performed based on the opening setting output θ set ═ Δ θ ± Δ θ blob (fixed) by increasing the opening θ r ═ θ s1 to the opening θ r ═ θ s1+ Δ θ blob (fixed). Since the opening degree control is performed from the opening degree θ r closer to the target opening degree θ s than the line L2, the overshoot of the line L10 is suppressed to be lower than the overshoot of the line L1 as shown in fig. 8 (a). As a result, the voltage regulation time is shortened.

In addition, when a large overshoot occurs, the overshoot amount is reduced by increasing the gain factor by parameter adjustment of the PI controller in the past, but when the control gain is increased, the gain margin of the feedback system is reduced, and the oscillation phenomenon is likely to occur. However, in the present embodiment, the reduction of the overshoot is achieved without increasing the gain magnification, and therefore, the oscillation phenomenon due to the reduction of the gain margin of the feedback system does not occur.

(with respect to threshold)

In the example shown in fig. 8(a) and 8(b), the threshold value in step S12 is set to be equal to the target pressure Ps, but the method of setting the threshold value is not limited to this. For example, as described in japanese patent laid-open No. 2018-106718, the opening degree increment Δ θ blow may be output at the timing of reaching the dead zone control region. In the dead zone control region, the opening degree is maintained to be unchanged. Since the dead zone control region is generally set to about ± 5% of the target pressure Ps, for example, when the output opening degree increase Δ θ blob is lower than 5% of the target pressure Ps, the output is performed at a timing at which Pr is 0.95 Ps.

When equation (10) is applied to the case where overshoot occurs, the difference Pp04-Ps is only positive. In fig. 7, the predicted pressure Pp04 calculated at the timing Pr ═ Pr0 is equal to the target pressure Ps. Therefore, the pressure Pr at the timing of outputting the opening degree increase Δ θ blow is preferably set to Pr > Pr 0. For example, the opening degree increase generating unit 22 may calculate the predicted pressure Pp04 for each control cycle of the closing control, and output the opening degree increase Δ θ blow at a timing at which the calculated predicted pressure Pp04 exceeds Pp04> Ps of the target pressure Ps.

Here, the farther the difference Pp04-Ps is from t1 to the near side, the smaller the opening degree increase Δ θ blow is, and the smaller the overshoot reduction effect by adding the opening degree increase Δ θ blow is. Further, when the opening degree increment Δ θ blob is added to the timing at which t > t1, the peak of the overshoot cannot be estimated in advance, and thus it is difficult to set the timing. Further, in a situation where the pressure Pr is near the apex of the overshoot, the difference Pp04-Ps is large, but θ s — θ r is small, and therefore the opening degree increase Δ θ blow is larger than θ s — θ r, and the pressure adjustment time may be prolonged. Therefore, the output opening degree increase Δ θ blob is preferably set at a timing near the target pressure at t1, which includes Pr ═ Ps, as in the dead zone control region described above, or regardless of the presence or absence of the dead zone control region.

(modification example)

Since the expression Δ θ blob represented by the above expression (10) is an approximate expression, an error occurs in actual automatic voltage adjustment. Therefore, Δ θ blob calculated by equation (10) may be multiplied by a fixed coefficient according to actual conditions and output as an opening degree increment. As the coefficient, about 0.5 to 2 is practical. For example, when the opening degree increase Δ θ bow is output at a timing at which Pr is Ps and pressure is actually adjusted as described above, if the overshoot tends to be large, the value obtained by multiplying Δ θ bow calculated by equation (10) by the coefficient β (>1) is used as the opening degree increase.

Further, instead of the method of multiplying by the coefficient β, the opening degree increase Δ θ blob may be output at a timing before the pressure Pr reaches Ps (Pr < Ps). For example, when the opening degree increase Δ θ bow is output at a timing lower than the target pressure Ps by 3%, the opening degree increase Δ θ bow may be calculated by applying the opening degree θ r at a timing at which Pr is 0.97Ps to equation (10).

Alternatively, as another modification, the opportunity to output the opening degree increase Δ θ blob at the timing when the pressure Pr reaches the threshold value is only once as described above, but the output may be performed a plurality of times as long as the threshold value condition is satisfied. In this case, in order to eliminate the possibility of occurrence of the limit cycle phenomenon, the upper limit of the number of outputs may be set in advance. Further, it is effective to decrease the coefficient β value in the +0 direction in order as the number of times of the output opening degree increment Δ θ blow increases, and multiply the value to output.

In the above description, as shown in fig. 4(a) and 4(b), and fig. 8(a) and 8(b), the case of the pressure adjustment event in which the current target pressure is higher than the previous target pressure has been described as an example, but conversely, the case of the pressure adjustment event in which the current target pressure is lower than the previous target pressure can be similarly applied, and the same effects can be obtained. In the case of a pressure regulation event in which the target pressure Ps decreases, an undershoot (undershoot) occurs in which the pressure Pr is lower than the target pressure Ps, but in this case, (Pp04-Ps) of equation (10) becomes a negative value, and the opening degree increase Δ θ blow becomes a negative value, and therefore acts in a direction to decrease (close) the opening degree increase Δ θ blow and the opening degree θ r. As a result, undershoot is reduced.

Next, the operational effects of the above-described embodiment and modification are summarized.

(1) The valve control device 2 includes: a closing control unit 21 that generates an opening degree setting output Δ θ, which is an opening degree control signal by closing control, based on the target pressure Ps; and an opening degree increase generating unit 22 that generates an opening degree increase signal Δ θ bow corresponding to an opening degree difference from the chamber pressure at the timing t1 to the target pressure Ps in synchronization with the timing t1 at which the pressure Pr of the vacuum chamber 3 reaches the predetermined pressure threshold (Ps), and adds the opening degree increase Δ θ bow to the opening degree control signal Δ θ.

As shown in fig. 8(b), by adding the opening degree increment Δ θ blob to the opening degree setting output Δ θ at the timing t1, the opening degree θ r can be made to approach the target opening degree θ s very quickly, the overshoot can be reduced, and the pressure regulating time can be shortened. The timing of generating and adding the opening degree increment Δ θ blob is preferably, for example, the timing when the pressure threshold (Ps) is reached, but the same effect can be obtained even if the time is slightly delayed.

(2) The opening degree increase Δ θ blow is generated based on the opening degree θ r of the vacuum valve 1, the pressure Pr, the target pressure Ps, and the correlation Se (θ) and Gp (θ) between the opening degree θ and the effective exhaust speed Se, as shown in the above equations (6) and (10), for example. Ps1 and Pp04 in equations (6) and (10) are predicted pressures in a balanced state in which the opening degree of the timing t1 is maintained, and are predicted pressures after a relatively long time has elapsed from t to t 1. Pp04 is the predicted pressure after 0.4 seconds. Of course, the method of generating the opening degree increase signal Δ θ blob corresponding to the opening degree difference from the chamber pressure at the timing t1 to the target pressure Ps is not limited to the above.

(3) As the predetermined pressure threshold value, a predetermined pressure range including the target pressure Ps, for example, a pressure range of Ps ± 5% which is approximately the same as the width of the dead zone control region is set. Preferably, the target pressure Ps is set. By setting in this way, the desired opening degree increment Δ θ blob is added at a desired timing, effectively reducing the overshoot.

While the various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments considered within the scope of the technical idea of the present invention are also included in the scope of the present invention. For example, the vacuum valve 1 in which the valve plate 11 is driven to swing and the opening degree is changed has been described as an example, but the present invention is also applicable to a vacuum valve of an automatic pressure control type having another configuration.

Claims (5)

1. A valve control device that adjusts a chamber pressure of a vacuum chamber to a target pressure by opening-controlling a vacuum valve provided between the vacuum chamber and a vacuum pump by closing control, the valve control device comprising:

a signal generation unit that generates an opening degree control signal by closing control based on the target pressure; and

and an opening degree increase generating unit that generates an opening degree increase signal corresponding to an opening degree difference between the chamber pressure at the timing and the target pressure in synchronization with the timing at which the chamber pressure reaches the predetermined pressure threshold, and adds the opening degree increase signal to the opening degree control signal.

2. The valve control apparatus according to claim 1, wherein

The opening increase generating unit generates the opening increase signal based on a correlation between the opening of the vacuum valve, the chamber pressure, the target pressure, and the opening and an effective exhaust speed of the vacuum chamber.

3. Valve control device according to claim 1 or 2, wherein

The predetermined pressure threshold is set in a predetermined pressure range including the target pressure.

4. Valve control device according to claim 1 or 2, wherein

The predetermined pressure threshold is set to the target pressure.

5. A vacuum valve, comprising:

a valve body;

a valve body driving unit that drives the valve body to open and close; and

the valve control device according to any one of claims 1 to 4, wherein the opening/closing drive by the valve body drive unit is controlled.

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