JPH0826857B2 - Vacuum pump protection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a protection method for protecting a vacuum pump for exhausting a vacuum reaction chamber used for manufacturing a semiconductor or the like from damage.

[Conventional technology]

The vacuum pump rotates at high speed during exhaust operation, and the pressure on the intake side of the pump (intake pressure) and the pressure on the exhaust side (exhaust pressure)
The suction side is put into a high vacuum state by utilizing the difference of. At this time, if the difference between the intake pressure and the exhaust pressure is too large, the load applied to the blades of the pump increases, which may damage the pump itself.
Therefore, it is common to install a sluice valve on the intake side and exhaust side of the vacuum pump for the purpose of protecting the pump from damage, and to protect it from damage by an interlock that limits its opening and closing due to the difference in intake pressure and exhaust pressure. Target.

Also, the vacuum pump itself has a controller (pump controller), and performs ON / OFF of the pump motor, output of signals indicating the operating state, etc. for pump control. This pump controller is powered off (power failure)
Or a system reset will reset all of its functionality. Therefore, when the pump motor is in such a state (power failure) during steady operation, the pump motor is still rotating at high speed due to inertia.
The pump controller could not determine that, erroneously determined that it was stopped, and because the pump controller did not function normally, despite the electric braking of the pump motor,
As a result, the pump motor will continue to rotate due to inertia.

[Problems to be Solved by the Invention]

In other words, there is a problem that protection is insufficient in the case of a power failure or the like only by creating an interlock signal for pump protection using only the operation signal output by the pump controller and representing the state of the pump motor.

In other words, when the vacuum valves are started and stopped by the sluice valves (valves) attached to the intake side and the exhaust side of the pump, the operating state of the pump (acceleration state, constant speed state, deceleration state, stop state) It is said that the vacuum pump is damaged or protected by taking an interlock to open and close depending on the power supply.However, in the event of a power failure, the pump controller that outputs a signal that indicates the operating state of the pump is Since it will not function anymore, the vacuum pump cannot be sufficiently protected from damage if it is left as it is.

Therefore, it is an object of the present invention to obtain sufficient pump protection even in the event of a power failure.

[Means for solving the problem]

To achieve the above object, in the present invention, a vacuum pump for evacuating the vacuum reaction chamber to a vacuum state, and when the vacuum pump is started or stopped, the state of the vacuum pump before and after that, that is, acceleration, A pump controller for determining each state of constant speed, deceleration, and stop and outputting a signal indicating the state as a pump control signal, and the vacuum pump are arranged in an exhaust pipe line when exhausting the vacuum reaction chamber. , A valve that is opened and closed by interlocking so as not to damage the pump when starting and stopping the pump, and an interlock signal for preventing the pump from being destroyed from various signals including the pump control signal, An interlock circuit for instructing opening and closing by taking a required interlock for the valve, the vacuum reaction chamber, the vacuum pump, the In a vacuum device consisting of a computer that performs overall management including a lock circuit, the computer monitors whether or not there is a power outage and whether or not the vacuum pump has turned off in the absence of a power outage. If yes, a certain theoretical value is set as the flag information in the auxiliary storage device, and when the vacuum pump is turned off in the state of no power failure, another specific logical value is set as the flag information. , When a power failure occurs or the vacuum pump is turned off and it is necessary to generate an interlock signal to prevent the pump from being destroyed, the time at which the power failure occurs or the vacuum pump turns off. Information is taken into the auxiliary storage device, and the logical value of the flag information at that timing is referred to. The time at the current time that changes with the time and the timing time information are compared, and if the time difference between them exceeds a certain reference value, it is determined that the vacuum pump has actually reached a stop state, and the reference The value is switched depending on the logical value of the referenced flag information, and the timing signal of the determination made in this way is used in place of the signal indicating the stopped state of the vacuum pump output by the pump controller, Generated the required interlock signal.

[Action]

The computer that performs overall management of the entire system including the vacuum reaction chamber, the vacuum pump, and the interlock circuit periodically (requires deceleration of the pump) the operating state (whether rotating or stopped) of the turbo molecular pump and the current time. Sufficiently short time). On the other hand, the time until the turbo molecular pump stops is longer than when it is normally turned off because the controller cannot apply electric braking (brake) when it is forcibly turned off due to a power failure. Therefore, when the power is restored or the power is turned on, the computer reads the above operating state and the stop time stored in the auxiliary storage device, and the off flag information indicating whether the power was turned off normally or normally due to a power failure. By changing the criterion of the judgment time and checking whether the pump is rotating or stopped at the time of reading, a signal for correctly opening and closing the valve to prevent pump damage is output to the interlock circuit. To do.

〔Example〕

FIG. 1 shows a system configuration example of the present invention. 1 is a computer that controls the entire system, 2A is a dedicated controller that controls a vacuum device, 2B is a dedicated controller for other devices, 3 is a turbo molecular pump (TP), and 3A is a controller (pump controller) that controls this . 4 is a drive pump, 5 is a vacuum reaction chamber, 6A and 6B are load lock chambers, and 7A and 7B are gate valves. 8 is a hard interlock circuit, which limits the opening and closing of each valve from the standpoint of protecting the pump from damage. 9A and 9B are vacuum gauges, 10A and 10B are valves, and 11 is a high-speed communication line.

First, in order to bring the vacuum reaction chamber 5 into a high vacuum state, the computer 1 which manages the whole as a whole outputs an ON signal of the dry pump 4 to the dedicated controller 2A. As a result, the dry pump 4 starts rotating. Next, valve 10A
Is opened, and the inside of the pump is evacuated while the turbo molecular pump 3 in the stopped state is stopped. At this time, the timing of opening the valve 10B changes depending on the degree of vacuum in the vacuum reaction chamber 5.

If the degree of vacuum in the vacuum reaction chamber is significantly higher than that of the Tarvon molecular pump 3, the air will flow backward. Therefore, the valve 10B is opened after waiting until the operation of the tarvon molecular pump 3 becomes possible (that is, after the inside of the pump 3 becomes a vacuum state without backflow), and finally the turbo molecular pump 3 is turned on. Turn on. It takes about 20 to 30 minutes for the turbo molecular pump 3 to reach a steady rotation speed. Thereby, the vacuum reaction chamber 5 can be pulled to a high vacuum state.

Here, the case where the pump is stopped will be described.
To stop the vacuum reaction chamber while maintaining it in a high vacuum state, first close the valve 10B and then the turbo molecular pump 3
To OFF. At this time, in order to completely stop the turbo molecular pump 3, the brake is applied by the controller 2A for about 30 minutes and slowly stopped. Further, since it is necessary to secure the exhaust pressure side of the turbo molecular pump 3 until it is completely stopped, the dry pump 4 must continue to rotate. Therefore, after the turbo molecular pump 3 is completely stopped, the valve 10A is closed and the dry pump 4 is turned off to finish.

Next, a hard interlock that protects the turbo molecular pump 3 from damage will be described. Turbo molecular pump 3
Valves 10A and 10B are installed on the intake side and the exhaust side of the to protect the pump from damage. Here, if the dry pump 4 suddenly stops during evacuation by the turbo molecular pump 3, for example, the exhaust pressure of the turbo molecular pump 3 cannot be secured and the turbo molecular pump 3 will be broken.

Therefore, when the dry pump 4 is stopped while the turbo molecular pump 3 is rotating, the valve 10B on the intake side is instantaneously closed for protection by a hard interlock. This hard interlock is performed by obtaining a signal that the turbo molecular pump 3 is rotating from the pump controller 3A and using it. Therefore, the signal that the turbo molecular pump 3 is rotating is a very important signal, and accurate information must be given in any case.

As already mentioned, when an abnormality such as a power failure occurs, the pump controller 3A will continue to function normally, and the signal that the turbo molecular pump 3 is rotating cannot be obtained.
The hard interlock does not work well, and the turbo molecular pump 3 is not sufficiently protected from damage.

Therefore, a method of generating the signal (signal indicating that the turbo molecular pump 3 is rotating) according to the present invention when an abnormality such as a power failure occurs will be described with reference to FIGS. 2 and 3. 2 and 3 are flowcharts showing the operation of the computer 1 related to the present invention.

The integrated computer 1 is connected to the dedicated controller 2A by a high-speed communication line 11 to exchange information.
Here, the tasks for the computer 1 to monitor the operating status of the turbo molecular pump 3 include turning on / off the vacuum pump, accelerating,
The information indicating that the vehicle is decelerating or stopped is captured at high speed and cyclically (several hundreds of msec) according to the operation flow shown in FIGS. 2 and 3. That is, in FIG. 2, the task of the computer 1 determines whether or not there is a power failure (abnormality occurrence) in the step following the start, and when YES, the off flag (OFFLG).
Is 2. If NO, then turbo molecular pump 3 (T
P) is in the off state, and if it is in the off state, the off flag (OFFLG) is set to 1.

This task is performed when the turbo molecular pump 3 is turned off, or when a power failure occurs, at the time and date (see FIG. 2) at that time, and the information 1 or 2 of the off flag (OFFLG) (normal OFF). Information (whether it is OFF due to a power failure) (see Fig. 2) is stored in the common memory area of the computer. Subsequently, in this case, if a power failure has occurred, after performing the above processing, the system including the computer 1 stops the system to prevent the battery from being consumed, and ends. If the turbo molecular pump 3 is not operating normally and the turbo molecular pump 3 is turned off as a normal operation, it returns to the original state.

In addition to the task, the information storage task is configured to execute the contents of the common memory area (date and time information at the present time and off flag (OF
FLG) information (1 or 2)) is fetched and stored in the auxiliary storage device FILE every 30 seconds (a cycle sufficiently shorter than the time required for deceleration of the turbo molecular pump 3) (see FIG. 2).

Next, as shown in FIG. 3, the computer 1 reads out the date and time stored in the auxiliary storage device FILE as the stop date and time of the turbo molecular pump 3 (TP) at the time of power restoration or power-on, and at that time, Compare with time (see FIG. 3). The difference is calculated (see FIG. 3), and depending on whether the OFF flag (OFFLG) information is 2 or not (that is, 1), the current time point is a certain time or more after the turbo molecular pump 3 (TP) stop time point. It is determined (see FIG. 3,).

That is, if the OFF flag (OFFLG) information is 2 (because a power failure has occurred), and if it is determined that the difference between and is 60 minutes, then the turbo molecular pump 3 (TP) also rotates by inertia. The stop flag is set to 0 as if it has been completed.
If it is determined that () has not elapsed for 60 minutes, the stop flag is set to 1 (), considering that the rotation by inertia is still continuing.

Then, if the off flag (OFFLG) information is not 2 but 2 (because the turbo molecular pump 3 (TP) stopped as normal operation), it can be considered that the brake operation will also work, so the judgment criterion is 60 minutes to 30 minutes. If it is determined that 30 minutes have not passed, the stop flag is set to 1 () because it is considered that the rotation by inertia is still continuing. If it is determined that 30 minutes have passed in, the turbo molecular pump 3 (TP) is regarded as ending the rotation by inertia and the stop flag is set to 0 ().
To

To explain the above in other words, forcibly due to a power outage
When it is turned off, the controller cannot apply electric braking (braking), so the time until it stops becomes longer than when it is normally turned off (60 minutes). Therefore, it is stored in the auxiliary storage FILE. OFF due to power failure
Based on the information (OFF flag information) indicating whether or not it is normally turned off, the criterion of the determination time is changed and checked (see FIG. 3). If the time has passed, the dedicated controller 2A is stopped via the communication line, and if the time has not passed, the rotation is notified and a corresponding operation is requested (see FIG. 3). The dedicated controller receives it and inputs the signal of rotating / stopping to the hard interlock circuit, thereby turbo molecular pump 3 (TP)
Accurate judgment of the operating status of.

〔The invention's effect〕

According to the present invention, the operation status of the pump at the time of power failure is monitored by the computer that integrally manages the entire pump. Therefore, at the time of power failure (when an abnormality occurs), an accurate pump There is an advantage that the state can be grasped by the computer and the protection of the pump can be surely realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration example of the present invention, and FIG.
FIG. 3 is a flow chart for explaining the state monitoring operation of the turbo molecular pump, and FIG. 3 is a flow chart for explaining the initial processing. Explanation of code 1 …… General control computer, 2A …… Vacuum equipment controller, 2B …… Other equipment controller, 3 …… Turbo molecular pump (TP), 3A …… Pump controller, 4 ……
Dry pump, 5 ... vacuum reaction chamber, 6A, 6B ... load lock chamber, 7A, 7B ... dividing valve, 8 ... hard interlock circuit, 9A, 9B ... vacuum gauge, 10A, 10B ... valve, 11 ...
… Communication line.

Claims (1)

[Claims] 1. A vacuum pump for exhausting a vacuum reaction chamber to a vacuum state, and states of the vacuum pump before and after the vacuum pump is started or stopped, that is, acceleration, constant speed, deceleration, A pump controller that determines each stop state and outputs a signal indicating the stop state as a pump control signal, and the vacuum pump is arranged in an exhaust pipe line when exhausting the vacuum reaction chamber and starts the pump. , A valve that is opened and closed with an interlock so that the pump is not damaged when stopped, and an interlock signal that does not destroy the pump are generated from various signals including the pump control signal, and the valve is required based on the interlock signal. Including an interlock circuit for instructing opening and closing by taking an interlock with the vacuum reaction chamber, vacuum pump, and interlock circuit In a vacuum apparatus consisting of a computer, to carry out the body overall management of the computer, the presence or absence of a power failure, monitors whether or not off vacuum pump operating in a state of a power failure-free,
When there is a power failure, a certain specific theoretical value is set as flag information in the auxiliary storage device, and when the vacuum pump is turned off in the absence of power failure, another specific logical value is set as the flag information. When a power failure occurs or the vacuum pump is turned off, it is necessary to generate an interlock signal to prevent the pump from being destroyed. This indicates the timing at which the power failure occurred or the vacuum pump turned off. While capturing the time information in the auxiliary storage device, referring to the logical value of the flag information at that timing, the time at the current time point that changes with the passage of time, and
The timing time information is compared, and when the time difference between them exceeds a certain reference value, it is determined that the vacuum pump has actually reached a stop state, and the reference value is set to the logic of the above-mentioned flag information. It is switched depending on the value, and the timing signal for the determination made in this way is used in place of the signal indicating the stopped state of the vacuum pump output from the pump controller to generate the required interlock signal. A method for protecting a vacuum pump, which is characterized in that