JPH04140498A - Exhaust device - Google Patents

Abstract

PURPOSE:To adjust a temperature of a turbo molecular pump so as to suppress sublimation of a reaction product in a pump by connecting the turbo molecular pump, constituting an exhaust device, to an auxiliary pump through a liquid circulating mechanism. CONSTITUTION:An exhaust port 1b of a magnetic bearing turbo molecular pump 1 is connected to a suction port 2a of a dry pump 2, which is an auxiliary pump, through an exhaust route l, interposing a valve 32, and a suction port 1a is connected to an etching chamber 4, which is an exhaust object, by an exhaust route l interposing a valve 31. A liquid circulating mechanism(water jacket)2c is provided in the dry pump 2, and cooling water is introduced from a cooling water source 5 to cool the inside, changed into warm water and allowed to flow out. A water jacket 1c, which is a liquid circulating mechanism, is buried in the bottom part of a base of the turbo molecular pump 1, and water after circulation is discharged by connecting one end of the water jacket 1c to the water jacket 2c of the dry pump 2 and drawing around the other end outside a device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an exhaust device that is mainly composed of a turbo-molecular pump and is particularly suitable for exhausting process gas.

[Prior Art] Recently, there have been increasing opportunities to use exhaust devices using turbomolecular pumps in semiconductor manufacturing equipment. Semiconductor manufacturing equipment requires a clean quality vacuum, so to avoid oil contamination, turbo molecular pumps that use magnetic bearings are preferred over bearings.

In a turbomolecular pump using a magnetic bearing, the rotating body floats due to the action of the magnetic bearing and rotates completely without contact. The heat source inside this pump is:
■ Heat generated by the motor and electromagnet ■ Heat generated by friction with the rotating body due to the viscous resistance of the exhaust fluid, but since it is a high vacuum pump and the gas density inside the pump is small, the heat generated by ■ is small.
Furthermore, the heat generated by ■ is itself very small. For this reason,
This type of turbomolecular pump has the characteristic that its temperature rise is small as long as it is operated at room temperature, even without the provision of a cooling mechanism.

On the other hand, as an auxiliary pump that constitutes a series exhaust system together with this turbo molecular pump, it is recommended to use a dry pump (roots type, turbo type, screw type, etc.) that does not have to worry about oil contamination instead of the conventional oil rotary vacuum pump. are increasing. Since this dry pump is used in a low vacuum region, unlike the above-mentioned turbo-molecular pump, the gas density inside the pump is high and heat generation due to viscous friction with the rotating body is large. For this reason, conventionally, a liquid circulation mechanism using cooling water has been provided to control the internal temperature.

This liquid circulation mechanism differs depending on the purpose of use and the type of pump, but when the auxiliary pump is used under normal conditions, the inlet temperature of the cooling water is usually set at 20 to 25 degrees Celsius. On the other hand, the outlet temperature of the cooling water varies depending on the capacity of the auxiliary pump, but is generally 60°C.
It is often discharged at a temperature of ~70°C.

Problems to be Solved by the Invention] By the way, when such an exhaust device is applied to recent semiconductor manufacturing equipment, a problem arises in that reaction products adhere and accumulate inside the turbomolecular pump.

For example, when semiconductor manufacturing equipment is used for aluminum dry etching, chlorine-based process gases (CCρ4, BCD3, CI
2, etc.), the process gas reacts with Aρ, and the reaction products A, Q CΩ3 are also mixed in the gas, but this AffCJ23 has a temperature at which it becomes solid due to its vapor pressure characteristics. is often below the operating temperature of the turbomolecular pump, and when taken into the pump it solidifies by sublimation and tends to adhere and accumulate inside the pump.

Such problems are not limited to magnetic bearing systems, but similar situations occur even in bearing systems where the pump chamber is lowered below the sublimation temperature by water cooling or air cooling to protect the bearing system from burnout.

In order to avoid the above-mentioned problems, it is possible to use a heater to heat the areas where reaction products tend to adhere, but using a heater too easily can lead to deterioration and short circuits in the wiring over many years of use. This is easily predicted and requires a control mechanism to turn the heater on and off, which increases inconvenience in terms of maintenance and cost.

The present invention aims to appropriately solve these problems with a simple configuration.

[Means for Solving the Problems] In order to achieve the above object, the present invention takes the following measures.

That is, the exhaust device of the present invention includes a turbo molecular pump,
An exhaust device consisting of an auxiliary pump, in which both pumps are provided with a liquid circulation mechanism and connected between them, and the refrigerant that has been passed through the liquid circulation mechanism of the auxiliary pump is subsequently introduced into the liquid circulation mechanism of the turbomolecular pump. It is characterized by the fact that

[Operation] With such a configuration, when the refrigerant, which has been heated by giving cold heat while flowing through the liquid circulation mechanism of the auxiliary pump, is introduced into the liquid circulation mechanism of the turbo molecular pump, as described above, Since the internal temperature of the turbomolecular pump is relatively lower than the internal temperature of the auxiliary pump, the refrigerant conversely brings heat into the pump. As a result, the temperature inside the pump increases, which acts in a direction that prevents sublimation of the reaction product. Moreover, with such a configuration, when the temperature of the turbo molecular pump rises above the temperature of the refrigerant due to heat generation from the bearings, motor, etc., the refrigerant can perform its original cooling function.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, this exhaust system consists of an exhaust system path g that connects an exhaust port 1b of a magnetic bearing turbomolecular pump 1 and an intake port 2a of a dry pump 2, which is an auxiliary pump, with a valve 3□ interposed therebetween.
The inlet port 1a of the turbo molecular pump 1 is connected to the chamber (etching chamber) 4 for exhausting purposes by a valve 3,
They are connected by an exhaust system path g with an interposed one. As mentioned above, the dry pump 2 has a liquid circulation mechanism (water jacket) 2c, and has a liquid circulation mechanism (water jacket) 2c, which supplies water from the cooling water source 5 to 20 to 2
Cool the inside by introducing cooling water of about 5℃,
It is used to flow out as warm water at around ℃.

On the other hand, the specific configuration example of the turbo molecular pump 1 is as follows.
As shown in the figure, a water jacket IC serving as a liquid circulation mechanism is embedded in the bottom of the base 11. The base 11 on which the water jacket 1c is provided is made of a material with good thermal conductivity such as aluminum alloy, and supports the casing 15, and at the same time supports the upper and lower radial magnetic bearings 12, 13 and the thrust magnetic bearing 14. Encased in one piece. Therefore, the temperature of the base 11 is thermally connected to the area A where reaction products tend to adhere, and is also thermally connected to each magnetic bearing 12, 13, 14. Then, one end of the water jacket 1c is connected to the dry pump 2.
The water jacket 2C is connected to the water jacket 2C, and the other end is routed outside the device so that the water after circulation can be discharged.

When aluminum dry etching is started while exhausting the inside of the chamber 4 with the valve 6a of the gas cylinder 6 open using the exhaust system configured as described above, AρC is generated in the turbo molecular pump 1 along with the unreacted process gas.
l13 is flowing in.

If the sublimation temperature in the turbo molecular pump 1 of this AIC (13) is around 50°C under normal usage conditions, the water flowing from the dry pump 2 into the water jacket 1c of this turbo molecular pump 1 will reach a temperature of 60 to 70°C. The temperature is rising, and the entire inside of the pump is raised to a temperature close to that of the hot water.For this reason, the proportion of A1cΩ3 that becomes a solid phase becomes extremely small, and most of it passes through this turbo molecular pump 1 while remaining in a gaseous state. , will flow out into the exhaust flow path g toward the next dry pump 2. As a result, using this exhaust device will effectively prevent AρCg3 from adhering and accumulating inside the turbomolecular pump 1. Moreover, with this configuration, unlike heaters, the wiring does not deteriorate or short-circuit over many years of use.
In terms of configuration, there is no need for a control mechanism, so there are no maintenance or cost problems. Furthermore, with such a configuration, if the temperature of the turbomolecular pump 1 becomes close to the operating limit temperature of around 100°C for some reason (in fact, this possibility exists because the bearing support structure (This is often the case when
The water flowing into the turbomolecular pump 1 from the dry pump 2 effectively functions as cooling water, and the bearings can be appropriately protected from burnout.

In the above embodiment, a magnetic bearing type turbomolecular pump has been described, but the present invention is not limited thereto, and can of course be applied to a pump using ball bearings. Further, in the above embodiment, the auxiliary pump was explained as a dry pump, but if there is no problem in use, oil rotary vacuum pumps, mechanical booster pumps, etc. may also be used. In this case, if these pumps are used under the same conditions, it is expected that the temperature of the cooling water will be lower than 80°, but this can be easily countered by restricting the flow rate. Furthermore, in the above embodiment, A
If reaction products such as ρCρ3 tend to adhere, it is also effective to use the present invention to heat this area with the cooling water flowing out from the liquid circulation mechanism 2c of the auxiliary pump 2. In addition, various modifications can be made without departing from the spirit of the present invention, such as using a refrigerant other than water or having the liquid circulation mechanism constructed by routing pipes.

It should be noted that the change in cooling water temperature in the above embodiment is shown as an example, and it goes without saying that this value will vary depending on the capacity of the exhaust system, the purpose of use, etc.

[Effects of the Invention] Since the exhaust device of the present invention has the above-described configuration, the temperature of the turbomolecular pump is controlled by the refrigerant after cooling the auxiliary pump, and reaction products are difficult to sublimate inside the pump. Moreover, the effect of maintaining the temperature at which the bearing can be effectively cooled can be obtained. Moreover, compared to the case of using a heater, the maintenance cycle is longer and the cost is lower.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with FIG. 1 being a schematic circuit diagram and FIG. 2 being a schematic sectional view of a turbomolecular pump. 1...Turbo molecular pump IC...Liquid circulation mechanism (water jacket) 2...
・Auxiliary pump (dry pump)

Claims (1)

[Claims] An exhaust device consisting of a turbo molecular pump and an auxiliary pump, in which both pumps are provided with a liquid circulation mechanism and connected between them. An exhaust device characterized by being introduced into a circulation mechanism.