JPH07328410A - Evacuating device - Google Patents

Abstract

PURPOSE:To protect a vacuum pump from a gas at atmosphereic pressure by providing a valve to a vacuum pipeline connecting the vacuum pump and a vacuum vessel and opening or closing the valve based on the output of the pressure sensor set on the upstream side of the valve. CONSTITUTION:This evacuating device 3 consisting of a vacuum pump 1 and a vacuum pipeline 2 is connected to the reaction chamber 4 of a semiconductor producing device, for example. A valve 5 is provided at the outlet of the chamber 4, and a pressure sensor 6 and a special valve are successively furnished on the downstream side of the valve 5. The value detected by the sensor 6 is inputted to a controller 8, and, when the value exceeds a set value, the valve 7 is controlled by the controller 8 and throttled. Meanwhile, a loading and unloading chamber 10 is connected to the opposite side of the chamber 4 through a valve 11 and communicated with the atmosphere through the valve 11. Since the flow rate of the gas flowing into the vacuum pump 1 is limited by the special valve 7, a vacuum pump 1 of rigid structure need not be designed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a vacuum pump whose exhaust port is operated at atmospheric pressure, piping, and a vacuum container. In particular, like a back pump of a high vacuum pump used in a semiconductor manufacturing apparatus, The present invention relates to a vacuum evacuation device in which the pressure at the pump suction port is low, but air is sometimes introduced.

[0002]

2. Description of the Related Art A vacuum exhaust device used in a semiconductor manufacturing apparatus is designed to evacuate a vacuum container to a vacuum or to allow a process gas to continuously flow under a low pressure to cause a reaction in the vacuum container. Has a role to keep constant. When the pressure in the vacuum container is not too low, the vacuum pump used is often a medium or low vacuum pump alone. On the other hand, when it is necessary to make the inside of the vacuum container a high vacuum or an ultra high vacuum, a high vacuum pump is used as the main pump, and a medium or low vacuum pump is used as the back pump to maintain the back pressure. Further, recent semiconductor manufacturing apparatuses are increasingly equipped with load and unload chambers for loading and unloading wafers from the outside of the apparatus, and the reaction chambers are not usually exposed to the atmosphere. In such a case, the pressure in the reaction chamber is about several hundred Pa even if the pressure rises, and therefore the back pump of the exhaust device that exhausts the reaction chamber also has a suction port pressure of several thousand Pa.
It will never be higher than that. However, even in such a semiconductor manufacturing apparatus, it is necessary to expose the inside of the vacuum container to the atmosphere by cleaning the inside of the vacuum container or the like, and then to exhaust the inside of the vacuum container from atmospheric pressure. Therefore, the vacuum pump used in the exhaust device is designed so that the suction port pressure may be at atmospheric pressure, even though the pump suction port pressure is almost never at or near atmospheric pressure. I had no choice but to do it.

Further, depending on the semiconductor manufacturing process, foreign matter may be generated during the process, and when the vacuum vessel of the apparatus is rapidly evacuated from atmospheric pressure, the foreign matter in the vacuum vessel rises and adheres to the wafer. May adversely affect the subsequent process. At that time, in such a device, conventionally, in order to reduce the rise of foreign matter, an auxiliary pipe is provided separately from the main pipe of the vacuum pipe, and at the initial stage of exhausting from the atmosphere, the exhaust gas is exhausted through the auxiliary pipe by switching the valve. Had to do so.

[0004]

An object of the present invention is to provide a vacuum exhaust system comprising a vacuum pump, piping, and a vacuum container,
When the vacuum pump is operating in a steady state, protect the pump when gas at atmospheric pressure suddenly flows into the pump suction port from a vacuum container with an internal pressure connected to the upstream side of the vacuum pump. It is in. Another object of the present invention is to
This is to reduce the rise of foreign matter in the vacuum container when the inside of the vacuum container of the semiconductor manufacturing apparatus is rapidly evacuated from atmospheric pressure.

[0005]

In order to achieve the above object, the present invention is directed to a vacuum pipe between a vacuum pump and a vacuum container constituting an exhaust device, a special valve, and a pressure attached upstream of the special valve. A sensor and a controller for outputting a signal for opening and closing the valve by the output from the pressure sensor are provided.
When the pressure on the upstream side of the vacuum pump rises to or near atmospheric pressure, the special valve is throttled to limit the flow rate of gas flowing into the vacuum pump.

[0006]

According to the present invention, since the flow rate of the gas flowing into the vacuum pump can be limited, it is usually unnecessary for a vacuum pump whose intake port pressure is almost at or near atmospheric pressure. It eliminates the need for a robust structural design. Further, according to the present invention, it is possible to provide a vacuum evacuation device that reduces the rise of foreign matter in the vacuum container when the inside of the vacuum container of the semiconductor manufacturing apparatus is rapidly evacuated from the atmospheric pressure state.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the vacuum exhaust device of the present invention. Vacuum pump 3 consisting of vacuum pump 1 and vacuum piping 2
Is connected to the reaction chamber 4 of the semiconductor manufacturing apparatus. The reaction chamber 4 is a vacuum container. A valve 5 is attached to the outlet of the reaction chamber 4. Further, a special valve 7 is attached to the pressure sensor 6 immediately downstream of the valve 5 and to the side of the vacuum pipe 2 near the vacuum pump 1. The output signal of the pressure sensor 6 is sent to the control device 8, and when the output signal exceeds a certain set value, the control device 8 outputs a command signal for the special valve 7 to throttle the special valve 7. On the other hand, a load / unload chamber 10 is connected to the opposite side of the reaction chamber 4 via a valve 9 and communicates with the atmosphere via a valve 11. The load / unload chamber 10 is provided with an exhaust device different from the exhaust device 3 for exhausting the reaction chamber 4, but the illustration thereof is omitted. The operation of this vacuum exhaust device will be described below.

The single wafer type semiconductor manufacturing apparatus performs a film forming process and an etching process for each wafer. Therefore, in addition to the vacuum chamber for performing the process, that is, the reaction chamber 4, a load and unload chamber 10 for loading and unloading wafers from the atmosphere outside the apparatus is provided, and the reaction chamber is not normally exposed to the atmosphere. is increasing. When a film forming process or an etching process is performed in such an apparatus, a process gas is supplied to the reaction chamber 4 and the pressure in the reaction chamber 4 is kept constant while exhausting with the exhaust device 3. At this time, the valve 9 is closed. When a certain process is finished, the supply of the process gas is stopped and the exhaust device 3 exhausts the residual gas in the reaction chamber 4. At this time, a gas such as nitrogen that is difficult to react may be supplied to purge the gas. Then, the valve 5 is closed and the valve 9 is opened to move the wafer in the reaction chamber 4 into the loading / unloading chamber 10. Then, the valve 9 is closed and the valve 11 is opened, the wafer is taken out of the apparatus and the wafer to be processed next is put therein. During this time, since the valve 5 remains closed, the inside of the vacuum pipe 2 is in vacuum, and the reaction chamber 4 rises to the same pressure as the load / unload chamber 10, but is about several hundred Pa, which is still below atmospheric pressure. It is a sufficiently low pressure.

As described above, while the process is being performed in the reaction chamber 4, neither the vacuum exhaust device 3 nor the reaction chamber 4 is at atmospheric pressure or at a pressure close to atmospheric pressure. However, since dust inside the reaction chamber 4 is generated during the process, it is necessary to regularly clean the reaction chamber 4, and at that time, the reaction chamber 4 must be opened to the atmosphere. Further, when a failure occurs in the reaction chamber 4 or a device around the reaction chamber 4, it may be unavoidable to open the reaction chamber 4 to the atmosphere. Even in such a case, the vacuum pump 1 is usually left operating. If the vacuum pump 1 is stopped, the reaction product generated in the semiconductor manufacturing apparatus will be condensed or sublimated in the vacuum pump 1 and the rotating part of the vacuum pump 1 will be fixed, so that it can be restarted immediately. This is because it may disappear. Therefore, the reaction chamber 4
After the cleaning or repair of the above is completed, the valve 9 is closed, the valve 5 is opened, and the inside of the reaction chamber 4 is exhausted. At this time, atmospheric pressure air in the reaction chamber 4 flows into the vacuum pump 1 and must be operated at a high pump inlet pressure until the pressure in the reaction chamber 4 drops to some extent.

In the present invention, when the atmospheric pressure gas suddenly flows into the vacuum pump 1 as described above, the pressure sensor 6 detects the pressure change, and the control device 8 sets a certain output value from the pressure sensor 6. When the value exceeds the value, a command signal is sent to the special valve 7 and the special valve 7 is adjusted so as to be throttled. This reduces the flow rate of gas flowing into the vacuum pump 1,
The suction port pressure of the vacuum pump 1 can be suppressed to a low pressure of several hundred Pa or less. The special valve 7 may be a type valve whose opening can be adjusted like a butterfly valve. However, it is generally difficult to adjust the opening of the valve to a required opening in a short time, and a certain time delay occurs in the adjustment. Therefore, as a measure for reducing the time delay as much as possible, a special valve as shown in FIG. 2 is used. In the special valve shown in FIG. 2, an orifice 13 is provided in the valve body 12, and even if the valve is closed, a certain amount of gas can pass through the hole of the orifice 13. When the atmospheric pressure gas suddenly flows into the vacuum pump 1, the special valve 7 is closed at once by the command from the control device 8 without adjusting the opening, but the flow rate at which the valve is not completely closed is Can be flushed. This flow rate can be adjusted by increasing or decreasing the orifice diameter of the valve body as required.

FIG. 3 is a view showing a special valve according to another embodiment of the present invention, in which a stopper 14 is provided in the valve, and when the valve is closed, the valve body 12 is brought into contact with the stopper 14 so that the valve is completely closed. I try not to close it. When the atmospheric pressure gas suddenly flows into the vacuum pump 1, the special valve 7 is closed at once by the command from the control device 8 without adjusting the opening, but the stopper 14 does not completely close the valve. Some flow rate can be flowed without. This flow rate can be adjusted by setting the height of the stopper 14 high or low as necessary.

[0012]

According to the present invention, since the flow rate of the gas flowing into the vacuum pump can be limited, the vacuum pump which normally has almost no intake port pressure at or near atmospheric pressure is There is no need to make a structural design that is more robust than necessary. Further, according to the present invention, it is possible to provide a vacuum evacuation device that reduces the rise of foreign matter in the vacuum container when the inside of the vacuum container of the semiconductor manufacturing apparatus is rapidly evacuated from the atmospheric pressure state.

[Brief description of drawings]

FIG. 1 is a system diagram of a vacuum exhaust device showing an embodiment of the present invention.

FIG. 2 is a perspective view of a valve used in the embodiment of the present invention shown in FIG.

FIG. 3 is a perspective view of another valve used in the embodiment of the present invention shown in FIG.

[Explanation of symbols]

1 ... Vacuum pump, 2 ... Vacuum piping, 3 ... Vacuum exhaust device, 6
... pressure sensor, 7 ... special valve, 8 ... control device, 12 ...
Valve body, 13 ... Orifice, 14 ... Stopper.

Claims (1)

[Claims] 1. A vacuum pump, which operates at or near atmospheric pressure, having an exhaust port pressure, a vacuum container located upstream of the vacuum pump, and a vacuum pipe connecting the vacuum pump and the vacuum container. In the vacuum exhaust system, a valve attached to the vacuum pipe, a pressure sensor attached to the upstream side of the valve, and a controller that outputs a signal for opening and closing the valve according to the output from the pressure sensor. Vacuum exhaust device.