JP6594638B2 - Vacuum exhaust system - Google Patents

Description

  The present invention relates to a vacuum exhaust system used for exhausting a processing gas from a processing chamber used in a semiconductor device manufacturing apparatus or the like.

  Usually, a backup pump (hereinafter referred to as a backup pump) is provided for backup of a vacuum pump connected to a semiconductor device manufacturing apparatus. The purpose of using this backup pump is to evacuate the processing chamber during maintenance of the vacuum pump, and to evacuate the processing chamber when the vacuum pump is abnormal.

  The vacuum pump has a function of transmitting a speed reduction signal indicating an abnormal reduction in the rotational speed when the rotational speed is reduced to a preset speed lower limit value. The abnormal reduction in the rotation speed occurs when the processing gas sucked from the processing chamber is solidified in the vacuum pump to form a deposit, which prevents the rotation of the pump rotor. When such an abnormal decrease in rotational speed occurs, the pressure in the processing chamber increases, and the semiconductor device manufacturing apparatus detects the pressure abnormality and stops its operation.

  Therefore, the backup pump described above is provided to evacuate the processing chamber when the vacuum pump is abnormal. When the above-described speed reduction signal is transmitted from the vacuum pump to the control unit, the control unit connects the backup pump to the processing chamber, and exhausts the processing gas from the processing chamber by the backup pump.

Japanese Patent No. 4180265

  However, as shown in FIG. 11, when the speed reduction signal described above is transmitted from the vacuum pump, the rotational speed of the vacuum pump has already been greatly reduced. As a result, the pressure in the processing chamber may exceed the upper limit of the pressure threshold that can be processed, and the operation of the semiconductor device manufacturing apparatus may be stopped.

  Therefore, an object of the present invention is to provide an evacuation system capable of switching the evacuation operation from a vacuum pump to a backup pump before the rotation speed of the vacuum pump is greatly reduced.

In order to achieve the above-described object, an aspect of the present invention includes a suction pipe, a branch pipe and a backup pipe branched from the suction pipe, and an on-off valve and a backup valve attached to the branch pipe and the backup pipe, respectively. A vacuum pump connected to the branch pipe, a backup pump connected to the backup pipe, and an operation control unit for controlling the opening / closing operation of the on-off valve and the backup valve, the operation control unit, The rotation speed of the vacuum pump is compared with a threshold value. When the rotation speed of the vacuum pump is lower than the threshold value, the backup valve is opened and the backup valve is opened. Before closing the vacuum pump, the rotation speed of the vacuum pump is compared again with the threshold value. In is configured to close the on-off valve, the suction side pressure of the vacuum pump when the rotational speed of the vacuum pump is equal to the threshold value, than the pressure upper limit indicating an abnormal increase in the suction-side pressure It is an evacuation system characterized by low.

In a preferred aspect of the present invention, the vacuum pump is configured to transmit a speed reduction signal to the operation control unit when the rotation speed reaches a preset speed lower limit value. The value is larger than the speed lower limit value.
In a preferred aspect of the present invention, when the rotation speed of the vacuum pump is equal to or higher than the threshold value, the backup pump operates at a first rotation speed, and the rotation speed of the vacuum pump is lower than the threshold value. lower case, the backup pump you characterized by operating at the first higher than the rotational speed second rotational speed.

One reference example of the present invention includes a suction pipe connected to a processing chamber, a branch pipe and a backup pipe branched from the suction pipe, an on-off valve and a backup valve respectively attached to the branch pipe and the backup pipe, A vacuum pump connected to the branch pipe; a backup pump connected to the backup pipe; and an operation control unit that controls the opening and closing operation of the on-off valve and the backup valve, the operation control unit including the processing When the pressure in the chamber reaches a threshold value, the backup valve is opened and the on-off valve is closed, and the threshold value is a pressure upper limit value indicating an abnormal increase in pressure in the processing chamber. It is an evacuation system characterized by being lower.
One reference example of the present invention includes a suction pipe connected to a processing chamber, a branch pipe and a backup pipe branched from the suction pipe, an on-off valve and a backup valve respectively attached to the branch pipe and the backup pipe, A vacuum pump connected to the branch pipe; a backup pump connected to the backup pipe; and an operation control unit that controls an opening / closing operation of the on-off valve and the backup valve, the operation control unit including the vacuum Comparing the rotation speed of the pump with a threshold value, and when the rotation speed of the vacuum pump is lower than the threshold value, the backup valve is configured to be opened and the open / close valve is closed. When the rotation speed reaches a preset speed lower limit value, the speed reduction signal is configured to be transmitted to the operation control unit, The threshold value is greater than the speed lower limit value, and the pressure in the processing chamber when the rotation speed of the vacuum pump is equal to the threshold value is higher than the pressure upper limit value indicating an abnormal increase in pressure in the processing chamber. It is an evacuation system characterized by low.
In a preferred embodiment of the above reference example , when the rotation speed of the vacuum pump is equal to or higher than the threshold value, the backup pump is operated at a first rotation speed, and the rotation speed of the vacuum pump is lower than the threshold value. Is lower, the backup pump is operated at a second rotation speed higher than the first rotation speed.

  When the evacuation operation is switched from the vacuum pump to the backup pump, the suction side pressure, for example, the pressure in the processing chamber connected to the suction pipe is lower than the pressure upper limit value indicating an abnormal increase in the suction side pressure. Therefore, the vacuum pumping operation can be continued by the backup pump while preventing an abnormal increase in the suction side pressure.

It is a mimetic diagram showing one embodiment of an evacuation system. It is a graph which shows the time change of the rotational speed of a vacuum pump, and the suction side pressure of a vacuum pump. It is a figure which shows the state in which the backup valve was opened and the on-off valve was closed. It is a graph which shows the relationship between the rotational speed of a vacuum pump, and the suction side pressure of a vacuum pump. It is a flowchart explaining backup operation. It is a schematic diagram which shows other embodiment of an evacuation system. It is a figure explaining the threshold value used for embodiment shown in FIG. It is a schematic diagram which shows other embodiment of an evacuation system. It is a figure which shows the state by which the backup valve was opened and the 1st on-off valve was closed. It is a figure which shows the state which the backup valve was opened and the 2nd on-off valve was closed. It is a figure explaining the conventional backup driving | operation.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating an embodiment of an evacuation system. As shown in FIG. 1, the vacuum exhaust system is connected to a suction pipe 5, a branch pipe 6 and a backup pipe 8 branched from the suction pipe 5, a vacuum pump 10 connected to the branch pipe 6, and a backup pipe 8. The backup pump 12 is provided. The suction pipe 5 is connected to a processing chamber 1 provided in a semiconductor device manufacturing apparatus such as a CVD apparatus, a PVD apparatus, or an etching apparatus.

  On-off valve 15 and backup valve 16 are attached to branch pipe 6 and backup pipe 8, respectively. The on-off valve 15 and the backup valve 16 are connected to the operation control unit 20 via signal lines, and the on-off operation of the on-off valve 15 and the backup valve 16 is controlled by the operation control unit 20. The vacuum pump 10 and the backup pump 12 are connected to the operation control unit 20 by wireless communication or wired communication, and operations of the vacuum pump 10 and the backup pump 12 are controlled by the operation control unit 20. As a form of wired communication, there is digital communication or analog communication.

  The vacuum pump 10 and the backup pump 12 are each provided with an electric motor and an inverter (not shown), and current values of the rotation speeds of the vacuum pump 10 and the backup pump 12 are sent from the inverter to the operation control unit 20. The signal indicating the current value of the rotation speed may be communication, a signal converted into an analog signal such as voltage or current, or a signal converted into a pulse signal.

  In normal operation, the on-off valve 15 is open and the backup valve 16 is closed. Both the vacuum pump 10 and the backup pump 12 are operated. Therefore, in normal operation, the processing gas in the processing chamber 1 is exhausted by the vacuum pump 10. The operation control unit 20 is an analog signal output terminal or a digital signal output terminal for transmitting the operating state of the vacuum pump 10 and the backup pump 12, the abnormal operation of the pump, and the opening / closing states of the on-off valve 15 and the backup valve 16 to the host device (see FIG. Not shown).

  In the manufacture of a semiconductor device, while the processing gas is injected into the processing chamber 1, the vacuum pump 10 exhausts the processing gas from the processing chamber 1 and maintains the inside of the processing chamber 1 at a low pressure. The semiconductor device manufacturing apparatus includes a pressure sensor (not shown) that measures the pressure in the processing chamber 1. When the pressure in the processing chamber 1 exceeds a pressure upper limit value indicating an abnormal increase in pressure, the semiconductor device manufacturing apparatus forcibly stops its operation. Therefore, after the manufacture of the semiconductor device is started, the pressure in the processing chamber 1 must be kept lower than the upper pressure limit. However, when the processing gas is solidified in the vacuum pump 10 to form a deposit, the rotation speed of the vacuum pump 10 may decrease and the pressure in the processing chamber 1 may increase significantly.

  Therefore, in the present embodiment, the process chamber 1 is evacuated by the backup pump 12 before the pressure in the process chamber 1 reaches the upper pressure limit. FIG. 2 is a graph showing temporal changes in the rotation speed of the vacuum pump 10 and the suction side pressure of the vacuum pump 10 (that is, the pressure in the processing chamber 1). In the graph of FIG. 2, the vertical axis represents the rotational speed and the suction side pressure, and the horizontal axis represents time.

  As shown in FIG. 2, the operation control unit 20 stores (stores) a threshold value for switching the evacuation operation from the vacuum pump 10 to the backup pump 12 in advance. The operation control unit 20 is configured to open the backup valve 16 and close the on-off valve 15 when the rotation speed of the vacuum pump 10 is lower than a threshold value.

  FIG. 3 is a view showing a state in which the backup valve 16 is opened and the on-off valve 15 is closed. As shown in FIG. 3, when the backup valve 16 is opened and the on-off valve 15 is closed, the suction pipe 5 and the backup pump 12 communicate with each other, and the communication between the suction pipe 5 and the vacuum pump 10 is blocked. Accordingly, the processing gas in the processing chamber 1 connected to the suction pipe 5 is sucked by the backup pump 12.

  The threshold value is determined in advance based on the relationship between the rotation speed of the vacuum pump 10 and the suction side pressure of the vacuum pump 10 (that is, the pressure in the processing chamber 1). FIG. 4 is a graph showing the relationship between the rotation speed of the vacuum pump 10 and the suction side pressure of the vacuum pump 10. As can be seen from the graph shown in FIG. 4, the rotation speed of the vacuum pump 10 and the suction side pressure of the vacuum pump 10 are generally in an inversely proportional relationship.

  The threshold value in the present embodiment is a threshold value related to the rotation speed of the vacuum pump 10. As shown in FIG. 4, the threshold value is a predetermined rotation speed corresponding to the suction side pressure TP lower than the pressure upper limit value set in the semiconductor device manufacturing apparatus. That is, the suction side pressure TP of the vacuum pump 10 when the rotation speed of the vacuum pump 10 is equal to the threshold value is lower than the pressure upper limit value. Therefore, as shown in FIG. 2, when an abnormality occurs in the vacuum pump 10, the rotation speed of the vacuum pump 10 reaches a threshold before the suction side pressure reaches the pressure upper limit value. Evacuation is started. The suction side pressure quickly decreases and is maintained at the original value.

  Next, the backup operation according to the present embodiment will be described with reference to the flowchart of FIG. In step 1, the vacuum pump 10 is started. At the same time as or after the vacuum pump 10 is started, the backup pump 12 is started. The operation control unit 20 determines whether or not the actual rotational speed of the vacuum pump 10 is equal to or higher than the rated rotational speed of the vacuum pump 10 (step 2). When the actual rotational speed of the vacuum pump 10 is equal to or higher than the rated rotational speed, the operation control unit 20 starts monitoring the decrease in the rotational speed of the vacuum pump 10 (step 3).

  The operation control unit 20 compares the rotation speed of the vacuum pump 10 with a threshold value, and determines whether or not the rotation speed of the vacuum pump 10 is lower than the threshold value (step 4). When the rotation speed of the vacuum pump 10 is lower than the threshold value, the operation control unit 20 opens the backup valve 16 (step 5).

  The operation control unit 20 again determines whether or not the rotation speed of the vacuum pump 10 is lower than the threshold value (step 6). This is because the rotational speed may be temporarily reduced due to foreign matter contamination. If the rotation speed of the vacuum pump 10 increases and becomes equal to or greater than the threshold value again, the operation control unit 20 closes the backup valve 16 (step 7), and monitors the decrease in the rotation speed in step 3 again. Start. In step 6 described above, when the rotation speed of the vacuum pump 10 is lower than the threshold value, the operation control unit 20 closes the on-off valve 15 (step 8), thereby starting a backup operation.

  In order to reduce power consumption, the backup pump 12 may be in a standby operation until the backup operation is started. More specifically, when the rotational speed of the vacuum pump 10 is equal to or higher than the threshold value, the backup pump 12 operates at the first rotational speed, and when the rotational speed of the vacuum pump 10 is lower than the threshold value. The backup pump 12 may be operated at a second rotational speed that is higher than the first rotational speed. In order to avoid an increase in pressure when switching to the backup operation, the first rotation speed described above is preferably equal to or higher than the threshold value.

  In Step 4 described above, when the rotation speed of the vacuum pump 10 is equal to or higher than the threshold value, the operation control unit 20 determines whether an alarm signal is transmitted from the vacuum pump 10 (Step 9). This alarm signal is transmitted from the vacuum pump 10 to the operation control unit 20 when a malfunction such as an abnormal rise in temperature of the vacuum pump 10 or a communication function stop occurs. When the alarm signal is not transmitted, the operation control unit 20 starts monitoring the decrease in the rotational speed in Step 3 again. When the alarm signal is transmitted, the operation control unit 20 opens the backup valve 16 (step 10) and further closes the on-off valve 15 (step 8), thereby starting the backup operation.

  In general, a processing gas used for manufacturing a semiconductor device has a property of solidifying with a decrease in temperature. For this reason, the processing gas is solidified in the vacuum pump 10 to form deposits, which may hinder the rotation of the pump rotor. Therefore, the vacuum pump 10 has a function of transmitting a speed decrease signal indicating an abnormal decrease in the rotational speed when the rotational speed is reduced to a preset speed lower limit value. This speed reduction signal is sent to the operation control unit 20. The operation control unit 20 stops the operation of the vacuum pump 10 when receiving the speed reduction signal. The threshold value mentioned above is a value larger than the speed lower limit value. The operation control unit 20 may be configured to open the backup valve 16 and close the on-off valve 15 when receiving the speed reduction signal.

  The reason why the backup valve 16 is closed during the operation of the vacuum pump 10 is to prevent the processing gas from solidifying in the backup pump 12. Further, the reason why the backup pump 12 is operated even when the backup valve 16 is closed during the operation of the vacuum pump 10 is that the backup pump 12 promptly starts the evacuation operation when the pump operation is switched. This is to prevent an increase in pressure in the processing chamber 1.

  In the present embodiment, the rotation speed of the vacuum pump 10 is a pressure index value that indirectly indicates the suction side pressure. By using the rotation speed of the vacuum pump 10 as the pressure index value, a pressure sensor for measuring the suction side pressure becomes unnecessary. Therefore, the vacuum exhaust system of the present embodiment can be easily incorporated into an existing apparatus without installing a pressure sensor in an existing apparatus such as a semiconductor device manufacturing apparatus or without connecting to the existing pressure sensor with a signal line. Can do.

  When a semiconductor device manufacturing apparatus is newly installed, an evacuation system may be incorporated in the semiconductor device manufacturing apparatus together with a pressure sensor. In such a case, a pressure sensor may be connected to the operation control unit 20, and the operation control unit 20 may determine the measured value of the suction side pressure as a threshold value. FIG. 6 is a schematic view showing another embodiment of the vacuum exhaust system. Since the configuration and operation that are not particularly described are the same as those of the embodiment shown in FIGS. In this embodiment, the pressure sensor 21 is connected to the suction pipe 5. The pressure sensor 21 measures the suction side pressure of the vacuum pump 10, that is, the pressure in the suction pipe 5 and the processing chamber 1, and transmits the measured value of the suction side pressure to the operation control unit 20. In the present embodiment, the measured value of the suction side pressure is a pressure index value that directly indicates the suction side pressure.

  The operation control unit 20 determines whether or not the backup operation should be started by comparing the measured value of the suction side pressure with a threshold value. The threshold value in the present embodiment is a threshold value related to the suction side pressure of the vacuum pump 10. When the measured value of the suction side pressure reaches the threshold value, the operation control unit 20 opens the backup valve 16 and closes the open / close valve 15.

  FIG. 7 is a diagram illustrating threshold values used in the embodiment shown in FIG. As shown in FIG. 7, the threshold value is a value lower than the pressure upper limit value set in the semiconductor device manufacturing apparatus. Therefore, when the abnormality of the vacuum pump 10 occurs, the suction side pressure reaches the threshold value before the suction side pressure reaches the pressure upper limit value, and the vacuum pumping by the backup pump 12 is started.

  FIG. 8 is a schematic view showing still another embodiment of the vacuum exhaust system. Since the configuration and operation that are not particularly described are the same as those of the embodiment shown in FIGS. In the present embodiment, the suction pipe 5 is composed of a collecting pipe. Hereinafter, the suction pipe 5 is referred to as a collecting pipe 5. A plurality of inlets of the collecting pipe 5 are connected to exhaust ports of a plurality of booster pumps 25. These booster pumps 25 are respectively connected to the plurality of processing chambers 1.

  The first branch pipe 6A, the second branch pipe 6B, and the backup pipe 8 branch from the collecting pipe 5, and are connected to the vacuum pump 10A, the vacuum pump 10B, and the backup pump 12, respectively. The vacuum pump 10A, the vacuum pump 10B, and the backup pump 12 each function as a main pump. A first on-off valve 15A, a second on-off valve 15B, and a backup valve 16 are attached to the first branch pipe 6A, the second branch pipe 6B, and the backup pipe 8, respectively.

  In the present embodiment, switching from the normal operation to the backup operation is performed in the same manner as in the embodiment described with reference to FIGS. 1 to 5 described above. That is, when the rotation speed of the vacuum pump 10A is lower than the threshold value, the operation control unit 20 opens the backup valve 16 and closes the first on-off valve 15A as shown in FIG. When the rotational speed of the vacuum pump 10B is lower than the threshold value, the operation control unit 20 opens the backup valve 16 and closes the second on-off valve 15B as shown in FIG.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Processing chamber 5 Suction pipe 6, 6A, 6B Branch pipe 8 Backup pipe 10, 10A, 10B Vacuum pump 12 Backup pump 15, 15A, 15B On-off valve 16 Backup valve 20 Operation control part 21 Pressure sensor 25 Booster pump

Claims (3)

A suction pipe,
A branch pipe and a backup pipe branched from the suction pipe;
An on-off valve and a backup valve respectively attached to the branch pipe and the backup pipe;
A vacuum pump connected to the branch pipe;
A backup pump connected to the backup pipe;
An operation control unit for controlling the opening and closing operation of the on-off valve and the backup valve,
The operation control unit compares the rotation speed of the vacuum pump with a threshold value, and opens the backup valve and opens the backup valve when the rotation speed of the vacuum pump is lower than the threshold value. And before closing the on-off valve, the rotational speed of the vacuum pump is compared again with the threshold value, and if the rotational speed of the vacuum pump is lower than the threshold value, the on-off valve is closed. Configured as
The vacuum exhaust system, wherein a suction side pressure of the vacuum pump when a rotation speed of the vacuum pump is equal to the threshold value is lower than a pressure upper limit value indicating an abnormal increase in the suction side pressure. The vacuum pump is configured to transmit a speed reduction signal to the operation control unit when the rotation speed reaches a preset speed lower limit value,
The vacuum exhaust system according to claim 1, wherein the threshold value is larger than the speed lower limit value.   When the rotation speed of the vacuum pump is greater than or equal to the threshold value, the backup pump operates at a first rotation speed, and when the rotation speed of the vacuum pump is lower than the threshold value, the backup pump The vacuum exhaust system according to claim 1, wherein the vacuum exhaust system is operated at a second rotational speed higher than the first rotational speed.

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