WO2019077672A1

WO2019077672A1 - Vacuum valve control method

Info

Publication number: WO2019077672A1
Application number: PCT/JP2017/037453
Authority: WO
Inventors: 永井　秀明; 慧岩本
Original assignee: 株式会社ブイテックス
Priority date: 2017-10-17
Filing date: 2017-10-17
Publication date: 2019-04-25
Also published as: KR102277953B1; KR20200031161A; JPWO2019077672A1; JP6311087B1

Abstract

A vacuum valve control method in which a vacuum pump is attached to an exhaust port of a vacuum chamber via a vacuum valve, and the pressure in the vacuum chamber is adjusted to a target pressure after initiating a supply of gas to the vacuum chamber with the vacuum valve closed, said vacuum valve control method comprising: a measurement step for measuring, in advance, internal pressure data of the vacuum chamber at selected times, and also measuring, in advance, data of the degree of opening of the vacuum valve at the selected times; a calculation step for calculating, from the measured pressure data and the measured data of the degree of opening of the vacuum valve, a conductance indicating the ease with which the gas flows, as a function of the degree of opening of the vacuum valve; and an acquisition step for identifying a range of degrees of opening of the vacuum valve at which the calculated conductance is substantially the same as when the vacuum valve is fully opened, and acquiring a targeted degree of opening of the vacuum valve that is within the identified range of degrees of opening and that corresponds to a set threshold value. When the pressure in the vacuum chamber is to be adjusted to the target pressure, gas discharge is initiated with the vacuum valve set to the targeted degree of opening, instead of with the vacuum valve fully opened, and then the vacuum valve is gradually set to a degree of opening that ensures stable gas flow so that the target pressure is achieved and maintained.

Description

Control method of vacuum valve

The present invention relates to a control method of a vacuum valve for keeping the pressure in a vacuum chamber constant.

In various processes in the production of semiconductor devices, solar cells, liquid crystals, etc., means for forming a thin film on a wafer (semiconductor substrate such as silicon) or glass substrate by vacuum deposition, sputtering, CVD (chemical vapor deposition) or the like, For example, an etching means for masking the necessary portions of the film with a resist and etching away the unnecessary portions by corrosion, and an ashing means for removing the unnecessary resist after etching with ozone or plasma are used.

For example, in a sputtering apparatus, an inert gas such as Ar (argon) is introduced into a vacuum chamber in which a substrate is disposed, a high frequency voltage is applied at a predetermined degree of vacuum to generate plasma, and a target which is a material collides. The deposited material is attached to the substrate to form a thin film.

Although the gas is supplied into the vacuum chamber, in order to improve the quality of the product, it is necessary to control the pressure in the vacuum chamber with high accuracy so as to maintain a predetermined degree of vacuum. A vacuum pump is attached to the exhaust port of the vacuum chamber via a vacuum valve, and the gas flow rate is controlled by the degree of opening of the vacuum valve to keep the pressure in the vacuum chamber constant. As described in Patent Document 1, the invention of a pressure control method for obtaining a set exhaust gas amount by performing feedback control to follow the set pressure is also disclosed.

In pressure control, when the pressure is lowered and stabilized at the target pressure from the state where the gas supply is started in the vacuum chamber with the vacuum valve closed and the pressure becomes high, first try to exhaust the gas from the exhaust port at a stretch The vacuum valve is fully open. When the pressure in the vacuum chamber decreases, the vacuum valve is closed to reduce the flow rate of the exhausted gas, and when the target pressure is reached, the degree of opening of the vacuum valve is also stabilized.

Patent No. 5111519 gazette

The vacuum valve includes a butterfly valve that adjusts the opening degree by rotating the valve body through the rotary shaft through the exhaust port, and a pen that adjusts the opening degree by rotating the valve body like a pendulum and overlapping the exhaust port There is a drool valve etc. Although the butterfly valve requires a short time from full open to full close, if the discharge adheres to the rotary shaft passing through the exhaust port even when fully open, the opening and closing operation may be hindered. On the other hand, in the pendroll valve, the rotary shaft does not pass through the exhaust port, but it takes time from full open to full close. In the case of the pendrol valve, as the inner diameter of the exhaust port increases, the amount of movement of the valve body also increases, so the time required for movement also increases.

Therefore, an object of the present invention is to provide a control method of a vacuum valve which reduces the time until the target pressure in the vacuum chamber is reached by the operation of the vacuum valve.

In order to solve the above problems, in the method of controlling a vacuum valve according to the present invention, a vacuum pump is attached to an exhaust port of a vacuum chamber via a vacuum valve, and gas supply is started with the vacuum valve closed. Control method for controlling the pressure in the vacuum chamber to a target pressure, wherein the pressure data in the vacuum chamber and the opening data of the vacuum valve for bringing the pressure to the target pressure in advance are measured in time series Calculation step of calculating the conductance representing the flowability of the gas relative to the opening degree of the vacuum valve from the measured pressure data and the opening degree data, and the change in the calculated conductance is the vacuum A range which can be regarded as unchanged from one in the fully open state of the valve is specified, and the vacuum bag at the threshold set in the range is specified. Obtaining an instruction opening degree of the vacuum chamber, and setting the pressure in the vacuum chamber to a target pressure, opening the vacuum valve not to full opening but to the instruction opening degree to start gas exhaust; A stable opening of the vacuum valve with respect to a gas flow rate is maintained at a target pressure.

Further, in the control method of the vacuum valve, the threshold value is set within a range of 5% of the change of the conductance.

In the pressure control controller of the vacuum valve according to the present invention, the vacuum pump is attached to the exhaust port of the vacuum chamber via the vacuum valve, and the vacuum chamber is closed to start the gas supply with the vacuum valve closed. A pressure control controller for controlling to a target pressure, which measures, in time series, pressure data in the vacuum chamber and opening data of a vacuum valve for bringing the pressure into the target pressure in advance; the pressure data; From the opening data, a calculation unit that calculates the conductance representing the flowability of the gas relative to the opening of the vacuum valve, and the change in the conductance can be regarded as not changing from that in the fully open state of the vacuum valve An acquisition unit for specifying a range and acquiring an indicated opening degree of the vacuum valve at a threshold set within the range; When the inside of the chamber is set to the target pressure, the vacuum valve is not fully opened but the instruction opening degree is opened to start gas exhaust, the stable opening degree of the vacuum valve for the gas flow rate is maintained, and the target pressure is maintained. And a control unit.

The vacuum valve according to the present invention is characterized by being controlled by the pressure control controller.

According to the present invention, in the pressure control of the vacuum chamber, when the vacuum valve is initially opened, the instruction opening degree is slightly closed rather than the full opening, so that the reciprocation from the instruction opening degree to the full opening to return to the instruction opening degree It is possible to eliminate the unnecessary operation associated with the above, and to shorten the time until the opening of the vacuum valve is stabilized and the target pressure is maintained.

It is a figure explaining operation | movement of the valve body in the control method of the vacuum valve which is this invention. It is a block diagram showing a pressure control system to which a control method of a vacuum valve which is the present invention is applied. It is a block diagram of a pressure control controller in which the control method of the vacuum valve which is the present invention is carried out. It is a graph which shows the chamber pressure and valve-opening degree which were beforehand measured in performing the control method of the vacuum valve which is this invention. It is a graph which shows the conductance characteristic to the valve-opening degree beforehand calculated in performing the control method of the vacuum valve which is the present invention. It is a graph which shows the result when the control method of the vacuum valve which is this invention is implemented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, what has the same function attaches | subjects the same code | symbol, and description of the repetition may be abbreviate | omitted.

First, the control method of the vacuum valve which is this invention is demonstrated. FIG. 1 is a view for explaining the operation of the valve in the method of controlling a vacuum valve, wherein (a) shows a state where the valve is fully open, and (b) shows an opening degree of 50% or more and less than 100%. Indicates the state of

As shown in FIG. 1, the vacuum system 100 is a pressure control system for setting the inside of the vacuum chamber 110 to a predetermined degree of vacuum, and a vacuum pump 300 (see FIG. 1) via the vacuum valve 200 at the exhaust port 120 of the vacuum chamber 110. 2) is attached. In the present embodiment, an example in which a pendroll valve is used as the vacuum valve 200 is shown.

The pendrol valve has a valve body 210 of a size slightly larger than the exhaust port 120, an arm 220 for rotating the valve body 210, and a rotation shaft 230 serving as a fulcrum of rotation of the arm 220. The valve body 210 completely overlaps the exhaust port 120 at (the opening degree 0%), and the vacuum chamber 110 is sealed, and the valve body 210 does not overlap the exhaust port 120 at the fully open position (opening degree 100%). Moving. In addition, even if the opening degree is larger than 0% (for example, 5%), if the gas is not discharged, the fully closed position is set.

With the valve body 210 of the vacuum valve 200 in the fully closed position, supply of gas into the vacuum chamber 110 is started, and the opening degree of the vacuum valve 200 is adjusted to maintain the target pressure in the vacuum chamber 110. Thus, the flow rate of gas discharged from the exhaust port 120 is controlled.

Normally, when the pressure in the vacuum chamber 110 is high, the vacuum valve 200 is rotated from the fully closed position to the fully open position to discharge the gas as shown in FIG. It is kept fully open until it falls below the maximum emission according to the When the pressure in the vacuum chamber 110 is lowered to limit the flow rate of the discharged gas, the vacuum valve 200 is swung to adjust the degree of opening as shown in (b). And if it becomes a target pressure, the position of the valve body 210 will also be stabilized.

FIG. 2 is a block diagram showing a pressure control system to which a control method of a vacuum valve is applied. FIG. 3 is a block diagram of a pressure control controller in which a method of controlling a vacuum valve is implemented. In FIG. 3, the pressure control controller 400 is not included in the dashed line, and the vacuum system 100 includes the pressure control controller 400.

As shown in FIG. 2, in the pressure control system of the vacuum system 100, while supplying the gas 520 to the vacuum chamber 110, the pressure control controller 400 is used to control the flow rate of gas discharged to the vacuum pump 300. By controlling the opening degree, the pressure in the vacuum chamber 110 is maintained constant.

To supply the gas 520 to the vacuum chamber 110, the mass flow 500 may be used, and the mass flow controller 510 may measure the flow rate of the gas 520 and control the flow rate to a predetermined flow rate (for example, 50 sccm). In addition, since the gas 520 reacts in the vacuum chamber 110, the flow rate of the gas to be discharged is not necessarily the same as the flow rate of the supplied gas 520.

The pressure controller 400 measures the pressure in the vacuum chamber 110 with the vacuum gauge 130, and drives the open / close mechanism of the vacuum valve 200 so that the opening degree corresponds to the flow rate of the gas to be discharged to achieve the target pressure. Let The pressure controller 400 is also referred to as an APC (Adaptive Pressure Control) controller. In addition, the gas flow rate discharged | emitted can be estimated if the opening degree of the vacuum valve 200 is detected.

As shown in FIG. 3, the pressure controller 400 has an inflowing gas flow rate estimation unit 410, a correction unit 420, an opening degree calculation unit 430, a motor control unit 440, a conductance table generation unit 450, a pressure gain calculation unit 460, and the like. .

First, the inflowing gas flow rate estimation unit 410 detects the degree of opening of the vacuum valve 200 and estimates the gas flow rate discharged from the vacuum valve 200. Then, the pressure in the virtual vacuum chamber 110 is calculated based on the estimated exhaust gas flow rate, and the gas flowing into the vacuum valve 200 is actually calculated from the difference with the pressure in the vacuum chamber 110 measured by the vacuum gauge 130. Estimate the flow rate.

The correction unit 420 first uses a pressure value obtained by passing a pressure command value set as a target pressure through a first-order lag filter, and a pressure value obtained by removing noise from the measurement value of the vacuum gauge 130 via the first-order lag filter. Determine the pressure deviation. Then, a correction value for obtaining the exhaust gas flow rate is calculated based on the pressure deviation by PID control.

First, the opening degree calculation unit 430 sets, as the exhaust gas flow rate, a value obtained by applying the correction value calculated by the correction unit 420 to the inflow gas flow rate estimated by the inflowing gas flow rate estimation unit 410. Then, by calculating the conductance at the set exhaust gas flow rate, the opening degree of the vacuum valve 200 for obtaining the pressure instruction value is calculated.

The conductance (sccm / Pa) is represented by the gas flow rate (sccm) discharged from the exhaust port 120 with respect to the pressure (Pa) in the vacuum chamber 110, regarding the ease of gas flow at each opening of the vacuum valve 200. It shall be. The unit of pressure may be mTorr.

The motor control unit 440 drives the motor of the open / close mechanism in order to set the vacuum valve 200 to the opening degree calculated by the opening degree calculation unit 430. The opening degree of the vacuum valve 200 is detected by a sensor or the like, and is fed back to the inflowing gas flow rate estimation unit 410. Further, the pressure in the vacuum chamber 110 is also measured by the vacuum gauge 130, and is fed back to the inflowing gas flow rate estimation unit 410 and the correction unit 420.

The pressure controller 400 causes the opening degree calculation unit 430 to calculate how much conductance is necessary to discharge a predetermined gas flow rate, and the motor control unit 440 sets a vacuum valve at a position (opening degree) that meets the required conductance. Control is performed to stop the valve body 210 of 200.

Here, when the inside of the vacuum chamber 110 is set to a target pressure, the vacuum valve 200 is not fully opened and then the stable opening degree corresponding to the conductance is not set, but the instruction opening degree is opened to a certain degree without going to full opening. By starting the exhaust of the gas and setting the vacuum valve 200 to a stable opening, the operation time of the valve body 210 until it is maintained at the target pressure is shortened.

FIG. 4 is a graph showing the chamber pressure and the valve opening measured in advance for executing the control method of the vacuum valve. FIG. 5 is a graph showing the conductance characteristic with respect to the valve opening degree calculated in advance for executing the control method of the vacuum valve. The pressure controller 400 learns the conductance characteristic and uses it to control the vacuum valve 200.

As shown in FIG. 4, first, the pressure control controller 400 measures in advance the pressure data 600 in the vacuum chamber 110 and the opening degree data 610 of the vacuum valve 200 for making it the target pressure. The flow rate of gas flowing into the vacuum chamber 110 is controlled to a predetermined amount by the mass flow 500 and mass flow controller 510.

When it is desired to lower the pressure data 600 (for example, 0 Pa), the opening data 610 may be large (for example, 100%), and when it is desired to increase the pressure data 600 (for example, 1200 Pa or more), the opening The data 610 may be small (for example, 20% or less).

As shown in FIG. 5, next, from the measured pressure data 600 and opening degree data 610, a conductance 620 indicating the flowability of the gas with respect to the opening degree of the vacuum valve 200 is calculated. For example, if the opening data 610 is small (for example, 10%), the discharge of gas is suppressed, and if the opening data 610 is large (for example, 100%), the discharge of gas is promoted. When the opening degree data 610 becomes larger than 50%, the change of the conductance 620 becomes smaller.

Further, the variation of the calculated conductance 620 specifies a range that can be regarded as not changing from that in the fully opened state of the vacuum valve 200, and the opening degree data 610 of the vacuum valve 200 at the threshold 630 set within that range. Acquire as an indication opening.

For example, assuming that the range which can be regarded as not changing is up to 2%, the threshold value 630 is set to be 2% lower than the conductance 620 when the opening data 610 is 100%. It will be 70%, and it should be taken as the indicated opening degree. In addition, it is preferable to make the range which can be regarded as not changing into 5% or less.

FIG. 6 is a graph showing the results when the vacuum valve control method is executed, where (a) is the case where the indicated opening is 100% and (b) is the case where the indicated opening is 70% . As shown in FIG. 6, in a case where the pressure value 660 in the vacuum chamber 110 is about 1400 Pa and the opening value 670 of the vacuum valve 200 is about 20% when the target pressure 640 is about 7 Pa. is there.

As shown in FIG. 6A, when the control by the instruction opening 650 is not performed (that is, when the instruction opening 650a is set to 100%), first, the pressure controller 400 reduces the pressure value 660a at a stretch. The valve 200 is instructed to be fully opened, and the opening value 670a is increased to 100%.

Next, the pressure value 660a decreases as the flow rate of gas exhausted from the vacuum chamber 110 increases, and when it falls below the target pressure 640, the pressure control controller 400 controls the vacuum valve 200 to suppress the flow rate of discharged gas. Is instructed to close, and the opening value 670a decreases.

Furthermore, when the pressure value 660a approaches the target pressure 640 by adjusting the gas flow rate discharged from the vacuum chamber 110, the opening value 670a of the vacuum valve 200 is also adjusted and gradually stabilized (about 40% in this example) ). At this time, it took about 9 seconds until the target pressure 640 was reached.

When the instruction opening degree 650b is set to 70% as shown in FIG. 6B, the pressure control controller 400 first instructs the opening degree value 670b of the vacuum valve 200 to be 70%. The flow rate of the gas exhausted from the vacuum chamber 110 is almost the same level as in the case where the instruction opening degree 650a is 100%.

Next, the pressure value 660b decreases due to the increased gas flow rate discharged from the vacuum chamber 110, and when the pressure value 660b falls below the target pressure 640, the pressure control controller 400 controls the vacuum valve 200 to suppress the discharged gas flow rate. Is instructed to close, and the opening value 670b decreases.

Furthermore, when the pressure value 660b approaches the target pressure 640 by adjusting the flow rate of the gas discharged from the vacuum chamber 110, the opening value 670b of the vacuum valve 200 is also adjusted and gradually stabilized. At this time, it takes about 8 seconds to reach the target pressure 640, which is about 1 second shorter than the case where the indicated opening degree 650a is 100%.

When the valve body 210 of the vacuum valve 200 has a large weight, it takes time to turn in a pendulum shape from a state close to full close to a state close to full open, so move to a stable opening that becomes the target pressure 640 Affects the time until By shortening even one second, it is possible to greatly reduce the time of work that is repeated thousands of times a day.

As described above, in the pressure control of the vacuum chamber 110, when the vacuum valve 200 is first opened, the instruction opening degree is slightly closed rather than the full opening, so that the reciprocation from the instruction opening degree to the full opening returns to the instruction opening degree. The unnecessary operation accompanying the above can be eliminated, and the time until the opening of the vacuum valve 200 is stabilized and the target pressure is maintained can be shortened.

As mentioned above, although the Example of this invention was described, it is not limited to these. For example, the present invention can be applied not only to pendroll valves but also to butterfly valves and the like.

100: Vacuum system (pressure control system)
110: Vacuum chamber 120: Exhaust port 130: Vacuum gauge 200: Vacuum valve (pend roll valve)
210: Valve body 220: Arm 230: Rotary shaft 300: Vacuum pump 400: Pressure control controller (APC controller)
410: Inflow gas flow rate estimation unit 420: Correction unit 430: Opening calculation unit 440: Motor control unit 500: Mass flow 510: Mass flow controller 520: Gas 600: Pressure data 610: Opening data 620: Conductance 630: Threshold 640: Target Pressure 650: indicated opening 660: pressure value 670: opening value

Claims

A control method of a vacuum valve, wherein a vacuum pump is attached to an exhaust port of the vacuum chamber via a vacuum valve, and the supply of gas is started with the vacuum valve closed, to control the inside of the vacuum chamber to a target pressure. ,
Measuring in advance, in time series, pressure data in the vacuum chamber and opening data of a vacuum valve for setting the pressure data to a target pressure;
Calculating, from the measured pressure data and the opening data, a conductance representing the flowability of the gas relative to the opening of the vacuum valve;
An acquisition step of specifying a range in which the calculated change in the conductance can be regarded as not changing from that in the fully opened state of the vacuum valve, and acquiring the indicated opening degree of the vacuum valve at a threshold set within that range. And
When the pressure in the vacuum chamber is set to the target pressure, the vacuum valve is not fully opened but the instruction opening degree is opened to start gas exhaust, the stable opening degree of the vacuum valve with respect to the gas flow rate, and the target pressure To maintain
A control method of a vacuum valve characterized in that.
The threshold is set within a range of 5% of the change in the conductance.
The control method of the vacuum valve of Claim 1 characterized by the above-mentioned.
A pressure control controller having a vacuum pump attached to an exhaust port of the vacuum chamber via a vacuum valve and controlling the inside of the vacuum chamber which has started supplying gas with the vacuum valve closed to a target pressure,
A measurement unit which measures in advance the pressure data in the vacuum chamber and the opening data of the vacuum valve for bringing it to a target pressure;
A calculation unit that calculates, from the pressure data and the opening data, a conductance that represents the flowability of the gas relative to the opening of the vacuum valve;
An acquisition unit that specifies a range in which the change in the conductance can be regarded as not changing from that in the fully open state of the vacuum valve, and acquires the indicated opening degree of the vacuum valve at a threshold set within that range;
When the pressure in the vacuum chamber is set to the target pressure, the vacuum valve is not fully opened but the instruction opening degree is opened to start gas exhaust, the stable opening degree of the vacuum valve with respect to the gas flow rate, and the target pressure And a controller to maintain the
A vacuum valve pressure control controller characterized in that.
It is controlled by the pressure control controller according to claim 3.
A vacuum valve characterized by