JP6729436B2 - Automatic pressure control valve and vacuum pumping system - Google Patents

Description

The present invention relates to an automatic pressure control valve and a vacuum exhaust system.

In a vacuum apparatus such as an etching apparatus, a process gas is caused to flow into a process chamber while the chamber pressure is maintained at a predetermined pressure to perform a process. Therefore, an automatic pressure adjusting valve (also called an APC valve) is provided between the process chamber and the vacuum pump, and the pressure of the process chamber is controlled to a desired pressure by the automatic pressure adjusting valve (for example, Patent Document 1). reference).

JP, 2014-093497, A

However, an automatic pressure control valve used in an etching apparatus or the like is used in a high temperature state by a heater or the like in order to prevent product accumulation. In that case, the conductance of the automatic pressure control valve changes subtly due to the influence of temperature, and the effective exhaust speed of the exhaust system also changes. As a result, a gap may occur between the effective exhaust speed used for pressure regulation and the actual effective exhaust speed, and the pressure adjusting operation may become dull or unstable.

An automatic pressure adjusting valve according to a first preferred embodiment of the present invention is an automatic pressure adjusting valve which is arranged between a chamber and a vacuum pump and which adjusts a chamber pressure to a required pressure, and a temperature sensor for detecting a valve temperature. A storage unit in which the pumping speed of the exhaust system including the automatic pressure control valve and the vacuum pump or the valve conductance of the automatic pressure control valve is stored as a valve control characteristic, and the temperature detected by the temperature sensor during pressure control A correction unit that corrects the valve control characteristic based on the valve control characteristic corrected by the correction unit, the temperature detected by the temperature sensor, and the chamber pressure. Adjust chamber pressure.
An automatic pressure adjusting valve according to a second preferred embodiment of the present invention is arranged between a chamber and a vacuum pump, and in the automatic pressure adjusting valve for adjusting a chamber pressure to a required pressure, a temperature sensor for detecting a valve temperature, The automatic pressure control valve and the vacuum pump are included based on flow rate information of gas flowing into the chamber, a chamber pressure detection value at gas inflow, and a first detection temperature of the temperature sensor at gas inflow. A valve characteristic generation unit that generates an exhaust speed of an exhaust system, a storage unit that stores the exhaust speed generated by the valve characteristic generation unit as a valve control characteristic, the first detected temperature, and the temperature when the pressure is adjusted. A correction unit that corrects the valve control characteristic based on a second detected temperature detected by a sensor, a valve control characteristic corrected by the correction unit, a temperature detected by the temperature sensor, and a pressure based on the chamber pressure. Controls the opening of the adjustment valve .
In a further preferred embodiment, the storage unit stores temperature correction information for temperature-correcting the valve conductance of the first embodiment or temperature correction information for temperature-correcting the exhaust speed of the exhaust system of the second embodiment. Is stored, and the correction unit corrects the valve control characteristic based on the temperature correction information.
An automatic pressure adjusting valve according to a preferred embodiment of the present invention is arranged between a chamber and a vacuum pump, and adjusts the chamber pressure to a required pressure. Exhaust speed of an exhaust system including the automatic pressure control valve and the vacuum pump based on flow rate information of the inflowing gas, a chamber pressure detection value at the time of gas inflow, and a first detection temperature of the temperature sensor at the time of gas inflow For each of the plurality of different first detected temperatures, the plurality of exhaust speeds generated by the first generator, and the detection of the temperature sensor during pressure adjustment. A second generation unit that generates an exhaust speed of the exhaust system at the detected temperature during the pressure adjustment , based on the temperature .
A vacuum exhaust system according to a preferred embodiment of the present invention includes the above-described automatic pressure adjusting valve and a vacuum pump connected to the automatic pressure adjusting valve.

According to the present invention, pressure adjustment can be performed more quickly and stably.

FIG. 1 is a block diagram showing a schematic configuration of a vacuum exhaust system. FIG. 2 is a plan view of the valve body. FIG. 3 is a view showing an AA cross section of FIG. FIG. 4 is a diagram showing an example of the initial effective pumping speed. FIG. 5 is a flowchart illustrating an example of the learning operation. FIG. 6 is a flowchart showing a process following the flowchart of FIG. FIG. 7 is a diagram showing an example of the calibration S map. FIG. 8 is a diagram showing an example of changes in the conductance Cv due to changes in temperature. FIG. 9 is a diagram illustrating a modified example. FIG. 10: is a figure which shows typically the pressure change at the time of pressure adjustment.

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 the vacuum exhaust system of the present embodiment. In FIG. 1, the evacuation system is composed of an automatic pressure control valve 1 and a vacuum pump 4. For the vacuum pump, for example, a turbo molecular pump is used.

The automatic pressure control valve 1 is composed of a valve body 1a attached to a vacuum chamber 3 of a vacuum device and a valve controller 1b for controlling the operation of the valve body 1a. The vacuum chamber 3 is provided with a flow rate controller 32 for introducing gas into the chamber and a vacuum gauge 31 for detecting the pressure in the chamber. The data regarding the flow rate Qin [Pa·m ³ /s] output from the flow rate controller 32 is input to a controller (not shown) provided on the vacuum device side.

A valve plate (valve body) 12 provided on the valve body 1 a is opened and closed by a motor 13. The motor 13 is provided with an encoder 130 for detecting the opening of the valve plate 12. A detection signal of the encoder 130 (hereinafter referred to as an opening degree measurement value θr) is input to the valve controller 1b. The valve body 1a is provided with a temperature sensor 15 that measures the temperature of the valve body 1a. The temperature measurement value T of the temperature sensor 15 is input to the valve controller 1b. Further, the pressure measurement value Pr [Pa] measured by the vacuum gauge 31 is input to the valve controller 1b.

The valve controller 1b includes an opening control unit 21, a motor driver unit 22, a storage unit 23, an input operation unit 24, a correction unit 25, and a display unit 26. The target pressure value Ps is input to the valve controller 1b from the controller on the vacuum device side. The opening control unit 21 sets the opening command value θa based on the target pressure value Ps, the measured opening value θr, and the measured pressure value Pr. The motor driver unit 22 drives and controls the motor 13 based on the opening command value θa. The storage unit 23 stores valve control software and data. The valve controller 1b can input various commands by operating the input operation unit 24. The operating state of the automatic pressure control valve 1 and the like are displayed on the display unit 26. The function of the correction unit 25 will be described later.

FIG. 2 is a plan view of the valve body 1a as viewed from the vacuum chamber 3 side. The valve plate 12 provided in the housing 11 of the valve body 1a is oscillated by a motor 13. Flanges 110a and 110b (see FIG. 3) are provided on the front side and the back side of the housing 11. The valve plate 12 can be slid to an arbitrary position between a full blocking position C2 that faces the entire valve opening 111 and a full open position C1 that does not face the valve opening 111 at all.

The blocking state of the valve opening 111 by the valve plate 12 is represented by a parameter called opening. The opening degree is a ratio=(the swing angle of the valve plate): (the swing angle from the fully closed state until the valve opening 111 is completely released), which is expressed in percentage. The full shield position C2 in FIG. 2 has an opening of 0%, and the full open position C1 has an opening of 100%. That is, the conductance of the valve body 1a can be controlled by adjusting the opening degree of the valve plate 12. In the following, the opening degree will be represented by using the symbol θ.

FIG. 3 is a view showing an AA cross section of FIG. The housing 11 is provided with a seal ring 14 which can move up and down in the drawing. The drive mechanism of the seal ring 14 is not shown. FIG. 3 shows a state in which the seal ring 14 is moved to the uppermost position, and a gas flow path as shown by a broken line is formed. When the automatic pressure control valve 1 is closed, the seal ring 14 is moved downward to completely block the gas flow path.

The automatic pressure control valve 1 adjusts the opening degree (described later) of the valve body 1a so that the difference between the pressure measurement value Pr and the target pressure value Ps input as described later becomes zero, and the vacuum chamber 3 The pressure is adjusted to the target pressure value Ps. In order to control the opening of the automatic pressure adjusting valve 1 to adjust the pressure of the vacuum chamber 3, the gas flow rate, the opening θ, and the exhaust speed of the vacuum exhaust system with respect to the vacuum chamber 3 (hereinafter referred to as the effective exhaust speed). Call)).

Generally, the effective pumping speed Se is expressed by the following equation (1). In the equation (1), Sp is the pumping speed of the vacuum pump 4, and Cv is the conductance of the automatic pressure control valve 1. Since the conductance Cv of the automatic pressure control valve 1 varies depending on the opening θ, it is expressed as a function of the opening θ like Cv(θ). Therefore, the effective pumping speed Se in the equation (1) is also a function of θ.
1/Se=1/Sp+1/Cv (1)

From the equation (1), the effective pumping speed Se of the vacuum pumping system is expressed as Se=Sp·Cv/(Sp+Cv). That is, the effective pumping speed Se of the vacuum pumping system changes by changing the conductance Cv of the automatic pressure control valve 1. When the flow rate of the gas introduced into the vacuum chamber 3 is Qin, the pressure P in the vacuum chamber 3 is expressed as P=Qin/Se in a static state where the pressure is stable. Therefore, in order to control the pressure P of the vacuum chamber 3 to the required pressure target value Ps, the opening degree θ may be adjusted so that the effective exhaust speed Se of the vacuum exhaust system is Se=Qin/Ps. That is, the opening degree θ is adjusted so that the conductance Cv of the automatic pressure control valve 1 becomes Cv=Qin×Sp/(Ps×Sp-Qin).

The pressure adjustment of the vacuum chamber 3 by the automatic pressure adjustment valve 1 is performed using, for example, a pressure adjustment formula as shown in the following formula (2). Qin is the flow rate of the gas introduced into the vacuum chamber 3. Further, Se is an effective evacuation speed for the vacuum chamber 3, that is, an effective evacuation speed for the vacuum chamber 3 in which the conductance of piping or the like between the vacuum chamber 3 and the automatic pressure control valve 1 is added. V[m ³ ] is the volume of the vacuum chamber 3, and P[Pa] is the pressure in the vacuum chamber 3. As described above, when the pressure in the vacuum chamber 3 is stable, it is expressed as Qin=Se×P, but it is related to the pressure change when the pressure in the vacuum chamber 3 changes (dynamic state). The first term on the right side will be added. This expression (2) is stored in the storage unit 23.
Qin=V×(dP/dt)+Se×P (2)

Since the pressure adjusting equation shown in the equation (2) also relates to the volume V of the vacuum chamber 3, the valve controller 1b needs to acquire the chamber volume V of the vacuum device to which the valve body 1a is attached. Also, regarding the effective exhaust speed Se, it is preferable to use the effective exhaust speed with the vacuum exhaust system attached to the vacuum device in order to enhance the accuracy and stability of the pressure adjustment.

Therefore, in the present embodiment, when the correction unit 25 is provided in the valve controller 1b and the vacuum exhaust system is attached to the vacuum chamber 3, the effective exhaust speed of the vacuum exhaust system alone represented by the formula (1) (hereinafter Is referred to as the initial effective pumping speed.) An operation (hereinafter, referred to as a learning operation) for calibrating Se to the effective pumping speed in a state where it is attached to the vacuum chamber 3 is performed. With the vacuum exhaust system attached to the vacuum chamber 3, the operator can execute the learning operation by operating the input operation unit 24 of the valve controller 1b.

By the way, when the automatic pressure adjusting valve 1 is attached to the vacuum chamber 3 for use, the valve body 1a is heated by a heater or the like in order to prevent products from adhering to the automatic pressure adjusting valve 1. When the temperature of the valve main body 1a rises due to this heating, the conductance Cv of the automatic pressure control valve 1 changes due to a change in the size of the gap between the valve plate 12 and the housing 11, and due to this effect, the effective exhaust speed of the vacuum exhaust system. Se will change. In addition to the function of performing the learning operation described above, the correction unit 25 of the valve controller 1b also has a function of performing temperature calibration based on the valve temperature at the time of adjusting the effective exhaust velocity Se acquired by the learning operation.

(Explanation of learning operation)
As shown in the equation (1), the effective pumping speed Se of the vacuum pumping system is expressed by the pumping speed Sp of the vacuum pump and the conductance Cv of the automatic pressure control valve 1. The conductance Cv is represented as a function Cv(θ) of the opening degree θ, and the exhaust speed Sp of the vacuum pump 4 depends on the flow rate Q, and thus is represented as a function Sp(Q) of the flow rate Q. As a result, the effective pumping speed Se is expressed as a function Se(Q, θ) of the flow rate Q and the opening degree θ.

In the present embodiment, the effective pumping speed Se(Q, θ) of the vacuum pumping system calculated by the equation (1) from the pumping speed Sp(Q) and the conductance Cv(θ), or a preset chamber is set. The actually measured effective exhaust speed Se(Q, θ) is stored in the storage unit 23 as initial data (initial effective exhaust speed) of the effective exhaust speed Se used in the pressure adjustment formula (2).

FIG. 4 is a diagram showing an example of the initial effective pumping speed. In FIG. 4, the exhaust speed data Sij (where i,j=0,1,2,..., 9) relating to the initial effective exhaust speed Se(Q,θ) is shown as a plurality of gas flow rates Q0,Q1,. , Q9 and a plurality of opening degrees θ0, θ1,..., θ9 are represented as a two-dimensional map. Note that θ0=0 (%) and θ9=100 (%). Nitrogen gas or Ar gas is generally used as the type of gas to be exhausted. Below, this two-dimensional map of the initial effective pumping speed Se(Q, θ) will be referred to as the default S map.

For example, the exhaust speed data S32 represents the exhaust speed data when the gas flow rate is Q3 and the opening is θ2. As described above, the actual exhaust speed data S32 of the initial effective exhaust speed Se(Q3, θ2) is the conductance Cv(θ2) when the opening of the automatic pressure control valve 1 is set to θ2, and the vacuum at the gas flow rate Q3. It is calculated by substituting the pumping speed Sp(Q3) of the pump 4 into the equation (1). Alternatively, an effective exhaust speed obtained experimentally by setting the opening θ2 and the gas flow rate Q3 using a preset chamber may be used as the exhaust speed data S32.

In the learning operation, gas is caused to flow while the vacuum exhaust system (the automatic pressure control valve 1 and the vacuum pump 4) is attached to the vacuum chamber 3 of the vacuum device, and the effective exhaust speed actually measured at that time is used to show in FIG. Calibrate the default S map. Here, the S map after calibration will be referred to as a calibration S map, and the effective exhaust speed represented by the calibration S map will be referred to as a corrected effective exhaust speed Se1(Q, θ).

5 and 6 are flowcharts illustrating an example of the learning operation. This process is executed by the correction unit 25 of the valve controller 1b of FIG. In the learning operation, the opening degree control unit 21 controls the pressure based on the pressure measurement value Pr, the target pressure value Ps, the opening degree measurement value θr, and the pressure regulation formula (2) based on the command from the correction unit 25. I do. The initial effective exhaust speed Se(Q, θ) using the default S map is used as the effective exhaust speed Se in the equation (2). The operator operates the input operation unit 24 to display the setting screen on the display unit 26, and selects the learning operation from the setting screen. When the learning operation is selected on the setting screen, the learning process shown in FIGS.

In step S10, a screen requesting the input of the volume V of the vacuum chamber 3 is displayed on the display unit 26. The operator inputs the value of the capacity V according to the screen display. In step S20, it is determined whether or not the capacity V is input, and if there is input, the process proceeds to step S30.

In step S30, the flow rate selection screen is displayed on the display unit 26. For example, in the default S map shown in FIG. 4, ten kinds of gas flow rates Q from Q0 to Q9 are set, so that a flow rate selection screen for selecting any one of these ten kinds of gas flow rates is displayed. The operator selects the gas flow rate according to the instruction on the flow rate selection screen, and then performs the selection completion operation. In step S40, it is determined whether or not a selection completion operation is input, and if there is an input, the process proceeds to step S50.

In step S50, the display unit 26 displays a screen for instructing the start of gas inflow at the selected gas flow rate. The operator causes the gas to flow into the vacuum chamber 3 according to the screen display, and performs an operation of instructing the start of the tuning operation using the input operation unit 24.

In step S60, it is determined whether or not there is an operation for instructing the start of the learning operation by the operator. When a start instruction operation is input by the input operation unit 24, the process proceeds to step S70.

In step S70, it is determined whether a predetermined time has elapsed. This predetermined time is a waiting time until the pressure in the vacuum chamber 3 becomes stable after the gas has flowed in, and is set in advance. Instead of waiting until a preset predetermined time elapses, it may wait until the change in the pressure measurement value Pr of the vacuum chamber 3 becomes a predetermined threshold value or less.

In step S80, the parameter j when the opening degrees θ0 to θ9 in FIG. 4 are expressed as opening degrees θj is set to an initial value j=0. When the process of step S80 ends, the process proceeds to step S90 of FIG.

In step S90, the opening of the automatic pressure control valve 1 is set to θj. Here, when the process proceeds from step S80 to step S90, j=0 is set in step S80, so the opening degree θ is set to θ0 (=0). In step S100, a predetermined time is waited until the pressure in the vacuum chamber 3 becomes stable. In step S110, the pressure measurement value Pr of the vacuum chamber 3 measured by the vacuum gauge 31 of FIG. 1 is acquired.

In step S120, 1 is added to the current j to make it a new j. In step S130, it is determined whether j>9. If j>9, the process proceeds to step S140. If j is 9 or less, the process returns to step S90. That is, the processes from step S90 to step S130 are repeated for j=0 to 9. As a result, the pressure measurement value Pr at each of the opening degrees θ0 to θ9 is acquired.

In step S140, the exhaust speed data Sij(Qi, θj) at each opening θ0 to θ9 is calculated by using the following equation (3). The exhaust speed data Sij(Qi, θj) is the ij element of the two-dimensional calibration S map representing the corrected effective exhaust speed Se1(Q, θ). In Expression (3), Qi is the selected gas flow rate, and Pr(j) is the pressure measurement value acquired at the opening θj. This formula (3) is a formula obtained when “dP/dt=0” in the above formula (2), and can be applied to a static case where the pressure is constant.
Sij(Qi, θj)=Qi/Pr(j) (3)

In step S150, it is determined whether or not the exhaust speed data Sij(Qi, θj) calculated in step S140 is valid. As an example of the determination method, it is appropriate if the difference between the corresponding exhaust speed data Sij of the default S map and the calculated exhaust speed data Sij(Qi, θj) of the calibration S map is equal to or less than a preset threshold value. judge. The difference between the calculated exhaust velocity data Sij(Qi, θj) and the exhaust velocity data Sij of the default S map is that the volume of the vacuum chamber 3 is different from the chamber volume assumed in the default S map. , The effect of pipe conductance can be mentioned. As long as these influences are not large, the calculated exhaust velocity data Sij(Qi, θj) and the exhaust velocity data Sij of the default S map do not differ greatly.

Therefore, when Sij(Qi, θj) and Sij are significantly different from each other, it is determined that the calculated exhaust speed data Sij(Qi, θj) is not appropriate. The threshold value that is the criterion for determining validity is stored in the storage unit 23 in advance. If it is determined to be invalid in step S150, the process proceeds to step S155 to display a warning display on the display unit 26. On the other hand, if it is determined to be appropriate, the process proceeds from step S150 to step S160.

If it is determined to be appropriate in step S150, the exhaust speed data Sij(Qi, θj) of one row (one horizontal row) of the calibration S map corresponding to one of the flow rates Q0 to Q9 of the default S map shown in FIG. Is obtained. That is, 10 pieces of exhaust velocity data Sij(Qi, θj) based on the measured values were obtained as the calibration effective exhaust velocity Se1(Q, θ). Here, i (=0 to 9) represents that the gas flow rate is Qi, and j (=0 to 9) represents that the opening is θj.

In step S160, the exhaust velocity data of the predetermined region other than the row of the gas flow rate Qi is calculated using the exhaust velocity data Sij(Qi, θj) obtained as described above. Details of the calculation of the calibration effective pumping speed in the predetermined region will be described later. In step S170, a map (see FIG. 7) obtained by replacing a part of the default S map in FIG. 4 with the exhaust velocity data Sij(Qi, θj) acquired in steps S140 and S160 is used as a calibration S map. It is stored separately in the storage unit 23.

FIG. 7 is a diagram showing an example of the calibration S map generated as described above. In the calibration S map of FIG. 7, the exhaust speed data St60 to St69 calibrated for the gas flow rate Q6 is acquired. In the calibration S map of FIG. 7, the calibrated exhaust velocity data Sij(Qi, θj) is displayed like Stij.

Further, the exhaust speed data St59, St76 to St79, St84 to St89 and St93 to St99 in the region R1 surrounded by the thick line in FIG. 7 are calculated using the exhaust speed data St60 to St69 calibrated based on the actual measurement values. Exhaust speed data. Except for the exhaust speed data in the row of the gas flow rate Q6 and the exhaust speed data in the region R1, the other exhaust speed data uses the exhaust speed data of the default S map.

Next, the exhaust speed data of the region R1 will be described. The exhaust speed data St59, St76 to St79, St84 to St89, and St93 to St99 included in the region R1 are estimated by calculation using the exhaust speed data St60 to St69. As described above, in the default S map shown in FIG. 4, the effective exhaust speed when the exhaust speed Sp of the vacuum pump 4 is assumed to be the rated exhaust speed is used as the exhaust speed data Sij. Alternatively, an effective evacuation speed actually measured or calculated using a chamber having a preset predetermined volume is used. Therefore, the influence of the flow rate Q on the volume difference from the actual vacuum chamber 3 and the exhaust speed Sp is not taken into consideration.

Therefore, in the calibration S map shown in FIG. 7, for the gas flow rate Q6, the exhaust speed data St60 to St69 for the opening degrees θ0 to θ9 are obtained from the actual measurement values as described above. These exhaust speed data St60 to St69 include the influence of the performance deterioration of the vacuum pump 4 (influence of the flow rate Q) in the region where the intake pressure is high, and the influence of the volume of the vacuum chamber 3 actually used and the pipe conductance. Has been.

In the S maps shown in FIGS. 4 and 7, the conductance Cv of the automatic pressure control valve 1 becomes smaller than the exhaust speed Sp of the vacuum pump 4 in a region where the opening θ is small, and the effective exhaust speed calculated by the equation (1) is obtained. The conductance Cv is dominant in Se. Therefore, the change in the effective exhaust speed substantially depends on the change in the opening degree θ. On the other hand, in the region where the opening degree θ is large, the conductance Cv of the automatic pressure control valve 1 becomes larger than the exhaust speed Sp of the vacuum pump 4, and the change of the effective exhaust speed is governed by the change of the exhaust speed Sp. Therefore, in a region where the gas flow rate is large, the influence of the decrease of the exhaust speed Sp becomes remarkable.

Therefore, in the present embodiment, the calibration process using the actually measured exhaust velocity data St60 to St69 is performed in the region R1 where the influence of the decrease in the exhaust velocity Sp is particularly remarkable. For example, when calibrating the exhaust speed data S78 of FIG. 4 to the exhaust speed data St78 of FIG. 7, first, the ratio of the calibrated exhaust speed data St68 at the same opening θ8 and the exhaust speed data S68 of FIG. 4 ( Calculate St68/S68). Then, it is considered that the ratio between the calibrated exhaust speed data St78 and the exhaust speed data S78 shown in FIG. 4 becomes almost the same value. That is, the calibrated exhaust speed data St78 is calculated by the following equation (4).
St78=(St68/S68)×S78 (4)

The exhaust speed data St88, St98 with the same opening θ8 can also be obtained by multiplying the exhaust speed data S88, S98 of FIG. 4 by a coefficient (St68/S68). Similarly, for the calibrated exhaust speed data St76, St86, St96 relating to the opening degree θ6, the exhaust speed data S76, S86, S96 in FIG. 4 may be multiplied by a coefficient (St66/S66).

When the calibration S map of FIG. 7 is obtained by the above procedure, the calibration S map is stored in the storage unit 23 as described above. Then, in the pressure adjustment control, the valve opening degree is controlled based on the calibration S map.

The above-mentioned calibration S map is obtained on the assumption that the gas flow rate in the process of the vacuum chamber shown in FIG. 1 is Q6. Therefore, when the process is performed at another gas flow rate, the learning operation needs to be performed again at that gas flow rate. For example, when another process is performed at the gas flow rate Q4, a learning operation is separately performed at the gas flow rate Q4 to obtain the corrected exhaust speed data St40 to St49 instead of the exhaust speed data S40 to S49. Then, the exhaust speed data S40 to S49 in the row of the gas flow rate Q4 of the calibration S map stored in the storage unit 23 is rewritten with the corrected exhaust speed data St40 to St49.

(Explanation of temperature calibration)
Next, temperature calibration in the correction unit 25 will be described. As described above, the automatic pressure control valve 1 is heated by a heater or the like to prevent the product from adhering, and the temperature of the automatic pressure control valve 1 changes. When the temperature of the automatic pressure control valve 1 changes, the conductance Cv also changes. That is, even if the above-described learning operation is performed, the conductance Cv changes due to the change in the valve temperature due to the subsequent heating, which causes a problem that the pressure adjustment accuracy decreases.

FIG. 8 is a diagram showing an example of changes in the conductance Cv due to changes in temperature. The line L1 shows the conductance Cv (25° C., θ) when the valve temperature=25° C., and the line L2 shows the conductance Cv (120° C, θ) when the valve temperature=120° C. When the valve temperature rises in this way, the conductance value decreases. When the conductance Cv changes, the effective pumping speed Se calculated by the equation (1) also changes accordingly. Therefore, it is preferable to use the temperature-calibrated effective exhaust speed Se2 obtained by further temperature-calibrating the calibrated effective exhaust speed Se1 calibrated in the learning operation as the effective exhaust speed used during pressure regulation.

Temperature calibration is performed as follows. The initial effective pumping speed Se(Q, θ, T) of the exhaust system alone is represented by the above-mentioned formula (1), but the calibration effective pumping speed Se1(Q1 with the vacuum pumping system attached to the vacuum chamber 3 is used. , Θ, T) is expressed by the following equation (5). In the equation (5), C1 is a factor expressing the factor that lowers the effective pumping speed for the vacuum chamber 3, and is affected by the conductance of the pipe to the automatic pressure control valve 1, the shape of the vacuum chamber 3, and the like.
1/Se1=1/Sp+1/Cv+1/C1 (5)

Here, considering that C1 is larger than Sp and Cv and assuming 1/C1≈0, Se1≈Se, so the effect of temperature change of the conductance Cv on the calibration effective pumping speed Se1(Q, θ, T). It may be considered that is almost the same as the influence of the temperature change of the conductance Cv on the initial effective exhaust speed Se(Q, θ, T).

First, a reference temperature for temperature calibration is set, for example, a temperature of 25° C. is set as the reference temperature, and the initial effective exhaust speed Se(Q, θ, T) when the valve temperature is the temperature T is given by the following equation (6). To set. Se(Q, θ, 25° C.) is the initial effective pumping speed at the reference temperature (25° C.), and G(T, θ) is the temperature correction coefficient. The temperature correction coefficient G(T, θ) can be experimentally obtained by measuring the effective pumping speed at various temperatures T.
Se(Q, θ, T)=Se(Q, θ, 25° C.)×G(T, θ) (6)

Assuming that the valve temperature during the learning operation is T1, the initial effective exhaust speed Se(Q, θ, T1) before calibration by the learning operation is expressed by the following equation (7). When the valve temperature at the time of temperature rise (during pressure adjustment) is T2, the initial effective exhaust speed Se(Q, θ, T2) at the valve temperature T2 is equal to the initial effective exhaust speed Se(Q, θ, T1). It is expressed by the following equation (8).
Se(Q, θ, T1)=Se(Q, θ, 25° C.)×G(T1, θ) (7)
Se(Q,θ,T2)=Se(Q,θ,25°C)×G(T2,θ)
=Se(Q,θ,T1)×G(T2,θ)/G(T1,θ) (8)

By calibrating the initial effective exhaust speed Se(Q, θ, T1) by the learning operation, the calibrated effective exhaust speed Se1(Q, θ, T1) at the valve temperature T1 is obtained. Therefore, by replacing Se(Q,θ,T1) on the right side of the equation (8) with the calibration effective exhaust speed Se1(Q,θ,T1), the calibration effective exhaust speed at the valve temperature T2, that is, the temperature calibration effective exhaust speed. Calculate Se1 (Q, θ, T2). The temperature-calibrated effective pumping speed Se1 (Q, θ, T2) is expressed by the following equation (9) using the calibration effective pumping speed Se1 (Q, θ, T1) and the temperature correction coefficient G(T, θ). It
Se1(Q,θ,T2)=Se1(Q,θ,T1)×G(T2,θ)/G(T1,θ) (9)

The temperature correction coefficient G(T, θ) described above is stored in the storage unit 23. When the heating of the automatic pressure control valve 1 is started and the valve temperature T detected by the temperature sensor reaches the predetermined target temperature range, the correction unit 25 causes the initial effective exhaust speed Se(Q, θ, T). ) And the temperature correction coefficient G(T, θ) to calculate the temperature calibration effective pumping speed Se1 (Q, θ, T2), and the calculated temperature calibration effective pumping speed Se1 (Q, θ, T2) is stored in the storage unit. Store in 23. The opening degree control unit 21 performs pressure adjustment control based on the temperature calibration effective exhaust velocity Se1 (Q, θ, T2), the chamber volume V acquired by the learning operation, and the equation (2).

The temperature correction coefficient G(T,Q) is a temperature correction coefficient for the vacuum exhaust system. Instead of the temperature correction coefficient G(T,Q), the temperature correction coefficient for the conductance Cv of the automatic pressure control valve 1 is used. α(T,Q) may be used. In this case, the following may be considered.

The initial effective pumping speed Se(Q, θ, T) is expressed by the equation (1), but if the conductance Cv is replaced by α(θ, T)Cv in the equation (1), it becomes as shown in the equation (10). The initial effective pumping speed Se′(Q, θ, T) after temperature calibration is obtained.
1/Se'(Q, θ, T)=1/Sp+1/α(θ, T)Cv (10)

On the other hand, when the above temperature correction coefficient G(T,Q) is used, Se'(Q,θ,T) is Se'(Q,θ,T)=Se(Q,θ,T)×G It is expressed as (T,Q). Here, consider a case where the opening degree θ is large (set to θ1) and a case where the opening degree θ is small (set to θ2). When the opening θ is large (θ1), Cv>>Sp, so the right side of equation (10) approaches 1/Sp, and the right side of equation (1) also approaches 1/Sp. In this case, G(T,Q) can be considered as a correction coefficient approaching 1 as in G(T,Q)→1.

On the contrary, when the opening degree θ is small, Sp>>Cv. Therefore, the right side of the equation (10) approaches 1/α(θ2,T)Cv, and the right side of the equation (1) approaches 1/Cv. In this case, G(T,Q) can be considered to be a correction coefficient approaching α(θ,T) as G(T,Q)→α(θ2,T). From this, G(T,Q) can be represented by the temperature correction coefficient α of the automatic pressure control valve 1 as in the equation (11). Since it is considered that the temperature correction coefficient α does not depend on the gas flow rate Q, G(T,Q) is expressed as G(T) in the equation (11).
G(T)={(θ−θ1)/(θ1−θ2)}×α(θ,T)+1v (11)

As described above, as the temperature correction coefficient, G(T,Q) as the vacuum exhaust system may be used, or the temperature correction coefficient α(θ,T) for the single automatic pressure control valve 1 may be used. ..

(Modification)
In the above-described embodiment, the temperature correction effective pumping speed Se2(Q, θ, T2) is obtained using the temperature correction coefficient G(T, θ) stored in the storage unit 23. However, in the modified example described below, learning is performed for a plurality of temperatures during the learning operation, and the temperature-calibrated effective pumping speed during heating is obtained based on the results. Here, a case will be described in which the temperature calibration effective pumping speed for two temperatures T1 and T2 (for example, T1=25° C. and T2=120° C.) is obtained.

First, the valve temperature is set to the temperature T1 and the learning operation is performed to acquire the calibrated effective exhaust speed Se1(Q, θ, T1) at the temperature T1. Next, the automatic pressure adjusting valve 1 is heated to adjust the valve temperature to the temperature T2, and the learning operation is performed to obtain the calibrated effective exhaust speed Se1(Q, θ, T2) at the temperature T2.

FIG. 9A is a schematic diagram of the calibration effective pumping speeds Se1(Q, θ, T1) and Se1(Q, θ, T2). Further, FIG. 9B shows the calibration effective exhaust speeds Se1(Q, θ1, T1) and Se1(Q, θ1, T2) at the opening θ1. A straight line L10 in FIG. 9B is a straight line connecting the point indicating the calibrated effective exhaust speed Se1(Q, θ1, T1) and the point indicating the calibrated effective exhaust speed Se1(Q, θ1, T2). The calibration effective pumping speed Se1(Q, θ1, T) between the temperature T1 and the temperature T2 is obtained by approximating that on the straight line L10. That is, when the temperature at the time of pressure regulation is T3, the effective exhaust speed at the intersection of the perpendicular line passing through the temperature T3 on the temperature axis and the straight line L10 is calculated as the temperature calibration effective exhaust speed Se2(Q, θ1) at the valve temperature T3. , T3).

According to the above-mentioned embodiment, the following effects can be obtained.
(C1) In the automatic pressure control valve 1, the temperature sensor 15 for detecting the valve temperature, the exhaust speed of the exhaust system including the automatic pressure control valve 1 and the vacuum pump 4, or the valve conductance of the automatic pressure control valve 1 are used as valve control characteristics. A storage unit 23 that is stored and a correction unit 25 that corrects the valve control characteristic based on the temperature detected by the temperature sensor 15 during pressure adjustment are provided, and the valve control characteristic corrected by the correction unit 25 and the temperature sensor 15 The chamber pressure is adjusted by controlling the opening of the pressure adjusting valve based on the detected temperature and the chamber pressure.

Thus, by correcting the valve control characteristic based on the valve temperature (the temperature detected by the temperature sensor 15), the pressure adjustment by the automatic pressure adjusting valve 1 can be performed more quickly and stably.

FIG. 10: is a figure which shows typically the pressure change at the time of pressure adjustment. The line L11 shows the case where the calibration based on the valve temperature is not performed, and the line L12 shows the change when the temperature calibration is performed. If temperature calibration is not performed, the effective exhaust speed Se in the formula (2) used for pressure regulation is different from the actual effective exhaust speed at high temperature, so overshoot occurs with respect to the target pressure, and It takes time to settle down. On the other hand, in the case of the line L12, the temperature is calibrated with the temperature correction coefficient G(Q,T) as the vacuum exhaust system and the temperature correction coefficient α(θ,T) of the conductance Cv, so that the pressure adjusting operation is appropriately performed. The target pressure can be quickly adjusted without causing overshoot or undershoot.

More preferably, (C2), the correction unit 25 generates the calibrated effective exhaust speed Se1 which is the valve control characteristic when the automatic pressure control valve 1 and the vacuum pump 4 are mounted in the vacuum chamber 3. The correction unit 25 determines the calibration effective exhaust speed Se1 based on the flow rate information Qin of the gas flowing into the vacuum chamber 3, the chamber pressure detection value Pr at the time of gas inflow, and the temperature T detected by the temperature sensor 15 at the time of gas inflow. To generate. By storing the calibrated effective exhaust speed Se1 in the storage unit 23 and performing the opening control based on the calibrated effective exhaust speed Se1, the automatic pressure adjusting valve 1 is opened appropriately according to the environment of the device in which the valve is installed. Degree control can be performed.

Further, even when performing the learning operation, since the valve control characteristic is only corrected based on the detected temperature at the time of pressure adjustment, it is not necessary to perform the learning operation again at the temperature at each pressure adjustment.

(C3) Further, the valve conductance Cv or the vacuum exhaust which is the valve control characteristic based on the temperature correction coefficient α(θ,T) or G(Q,T) stored in the storage unit 23 regardless of the presence or absence of the learning operation. By correcting the effective pumping speed of the system, it is possible to perform an appropriate pressure adjusting operation according to the valve temperature.

(C4) Further, as described in the modified example shown in FIG. 9, a plurality of valve control characteristics Se1(Q, θ, T1), Se1(Q, θ, T2) having different detection temperatures T when performing the learning operation are used. As shown in FIG. 9B, the valve control characteristics Se1(Q, θ, T1), Se1(Q, θ, T2) and the valve control characteristics based on the detected temperatures T1, T2 during pressure adjustment are generated. May be corrected.

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

DESCRIPTION OF SYMBOLS 1... Automatic pressure control valve, 1a... Valve main body, 1b... Valve controller, 3... Vacuum chamber, 4... Vacuum pump, 15... Temperature sensor, 21... Opening degree control part, 23... Storage part, 25... Correction part

Claims (5)

In an automatic pressure adjustment valve that is arranged between the chamber and the vacuum pump and that adjusts the chamber pressure to the required pressure,
A temperature sensor that detects the valve temperature,
A storage unit in which an exhaust speed of an exhaust system including the automatic pressure control valve and the vacuum pump or a valve conductance of the automatic pressure control valve is stored as a valve control characteristic.
A correction unit that corrects the valve control characteristic based on the temperature detected by the temperature sensor during pressure adjustment,
An automatic pressure adjusting valve that adjusts the chamber pressure by controlling the opening of the pressure adjusting valve based on the valve control characteristic corrected by the correcting unit, the temperature detected by the temperature sensor, and the chamber pressure. In an automatic pressure adjustment valve that is arranged between the chamber and the vacuum pump and that adjusts the chamber pressure to the required pressure,
A temperature sensor that detects the valve temperature,
The automatic pressure control valve and the vacuum pump are included based on flow rate information of gas flowing into the chamber, a chamber pressure detection value at gas inflow, and a first detection temperature of the temperature sensor at gas inflow. A valve characteristic generation unit that generates the exhaust speed of the exhaust system ,
A storage unit in which the exhaust speed generated by the valve characteristic generation unit is stored as a valve control characteristic,
A correction unit that corrects the valve control characteristic based on the first detected temperature and the second detected temperature detected by the temperature sensor during pressure adjustment;
An automatic pressure control valve that controls the opening of the pressure control valve based on the valve control characteristic corrected by the correction unit, the temperature detected by the temperature sensor, and the chamber pressure . The automatic pressure control valve according to claim 1 or 2,
In the storage unit, the temperature correction information temperature correcting the valve conductance of claim 1, or the temperature correction information pumping speed for temperature correction of the exhaust system of claim 2 is stored,
The automatic pressure adjustment valve, wherein the correction unit corrects the valve control characteristic based on the temperature correction information. In an automatic pressure adjustment valve that is arranged between the chamber and the vacuum pump and that adjusts the chamber pressure to the required pressure,
A temperature sensor that detects the valve temperature,
An exhaust system including the automatic pressure control valve and the vacuum pump based on flow rate information of the gas flowing into the chamber, a chamber pressure detection value at the time of gas inflow, and a first detection temperature of the temperature sensor at the time of gas inflow A first generation unit that generates the exhaust speed of each of the plurality of different first detection temperatures,
Said first plurality of said pumping speed generated by the generation unit, the second based on the detected temperature of the temperature sensor at the time of pressure adjustment, to produce a pumping speed of the exhaust system in the temperature detected at the time of the pressure adjusting An automatic pressure control valve comprising: An automatic pressure control valve according to any one of claims 1 to 4,
A vacuum pump connected to the automatic pressure control valve;

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