JP3134261B2 - Exhaust device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention mainly includes a turbo molecular pump,
The present invention relates to an exhaust device particularly suitable for exhausting a process gas.

[Related Art] In recent years, opportunities to use an exhaust device using a turbo-molecular pump in a semiconductor manufacturing apparatus have increased. In semiconductor manufacturing equipment, a vacuum of clean quality is required, so that a turbo molecular pump using a magnetic bearing is preferred to a bearing using a magnetic bearing rather than using a bearing so that oil is not mixed.

Thus, in a turbo-molecular pump using a magnetic bearing, the rotating body floats by the action of the magnetic bearing, and rotates without contact. As a heat source inside the pump, there is a frictional heat generated by a motor and a rotating body due to a viscous resistance of an exhaust fluid generated by an electromagnet, but the heat generated by a high vacuum pump and a small gas density inside the pump is small, and , And the heat generation by itself is very small. For this reason, the turbo molecular pump according to this method is characterized in that the temperature rise is small as long as the turbo molecular pump is operated at room temperature without providing a cooling mechanism.

On the other hand, an auxiliary pump that constitutes a series exhaust system together with this turbo molecular pump is a dry pump (roots type,
Turbo type, screw type, etc.) are increasingly used. Since this dry pump is used in a low-vacuum region, it is characterized by a high gas density in the pump and a large amount of heat generation due to viscous friction with the rotating body, unlike the above-described turbo-molecular pump. Therefore, conventionally, a liquid circulation mechanism using cooling water is provided to control the temperature inside.
This liquid circulation mechanism differs depending on the purpose of use and the type of pump, but when the auxiliary pump is used in a normal state, it is customary to set the inlet temperature of the cooling water to 20 to 25 ° C, On the other hand, the outlet temperature of the cooling water varies depending on the capacity of the auxiliary pump, etc.
It is often discharged at around ℃.

[Problems to be Solved by the Invention] By the way, when such an exhaust device is applied to a recent semiconductor manufacturing apparatus, there arises a problem that a reaction product adheres and accumulates in the turbo molecular pump. For example, when a semiconductor manufacturing apparatus is used for aluminum dry etching, when a chlorine-based process gas (such as CCl ₄ , BCl ₃ , or Cl ₂ ) constantly flowing into a chamber is exhausted, the process gas is formed of Al. Reaction product AlCl formed by reacting with
₃ also come to coexist in the gas, this AlCl ₃ vapor pressure characteristics on, often temperatures as a solid phase is below a working temperature of the turbo-molecular pump, by sublimation when taken into the pump It solidifies and easily adheres and accumulates in the pump.

Such a problem is not limited to the magnetic bearing system, and the same situation occurs when the pump chamber is lowered to a sublimation temperature or lower by water cooling or air cooling in order to protect the bearing system from burning.

In order to avoid the above problems, it is only necessary to heat the portion where the reaction product is likely to adhere by using a heater.However, if the heater is used in a straightforward manner, the wiring may be deteriorated or short-circuited through many years of use. Inconveniences in terms of maintenance and cost are increased, for example, a control mechanism for turning on and off the heater is required in view of the configuration and the configuration is required.

An object of the present invention is to appropriately solve such a problem with a simple configuration.

[Means for Solving the Problems] The present invention employs the following means to achieve the above object.

That is, the exhaust device of the present invention is an exhaust device in which a series exhaust system is constituted by a turbo molecular pump and an auxiliary pump via an exhaust system path. A liquid circulation mechanism is also provided to connect the two liquid circulation mechanisms, and the refrigerant circulated through the liquid circulation mechanism of the auxiliary pump is continuously introduced into the liquid circulation mechanism of the turbo molecular pump so that the temperature near the exhaust port is controlled. It is characterized by having.

[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 turbo-molecular pump is relatively lower than the internal temperature of the auxiliary pump, heat is introduced into the pump by the refrigerant. Further, since the turbo-molecular pump and the auxiliary pump constitute a series exhaust system, the pressure near the exhaust port becomes negative, and the sublimation temperature of the reaction product is lowered. As a result, the temperature inside the pump, especially the base temperature, rises, and acts in such a direction as to hinder the adhesion and deposition of the reaction product near the exhaust port due to the sublimation of the reaction product. In addition, with such a configuration, when the temperature of the turbo-molecular pump rises above the temperature of the refrigerant due to heat generated by a bearing, a motor, or the like, the refrigerant can exhibit its original cooling function.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The exhaust system, as shown in FIG. 1, connected by an exhaust system path 1 which is interposed an inlet 2a and the valve 3 ₂ between the exhaust port 1b auxiliary pump serving dry pump 2 of the magnetic bearing turbo-molecular pump 1, An intake port 1a of the turbo molecular pump 1 is connected to a chamber (etching chamber) 4 for exhausting by an exhaust system ₁ having a valve 31 interposed therebetween. Dry pump 2
Liquid circulation mechanism (water jacket) as described above
The cooling water source 5 is used to introduce cooling water of about 20 to 25 ° C. from the cooling water source 5 to cool the inside, and to flow out as warm water of about 60 to 70 ° C.

On the other hand, a specific configuration example of the turbo molecular pump 1 is shown in FIG. 2, in which a water jacket 1c as a liquid circulation mechanism is embedded in the bottom of the base 11. The base 11 provided with the water jacket 1c is made of a member having a good heat transfer coefficient, such as an aluminum alloy, and supports the casing 15 while simultaneously supporting the upper and lower radial magnetic bearings 12, 13.
And the thrust magnetic bearing 14 are integrally enclosed. For this reason, the temperature of the base 11 is in the region A where the reaction product is likely to adhere.
To the magnetic bearings 12, 13, and 14. And that water jacket 1c
Is connected to the water jacket 2c of the dry pump 2 and the other end is drawn out of the apparatus so that the water after circulation can be discharged.

When the aluminum dry etching is started using the exhaust device configured as described above while exhausting the inside of the chamber 4 with the gas cylinder 6 valve 6a opened, the AlCl ₃ gas is introduced into the turbo molecular pump 1 together with the unreacted process gas. Comes in. Since the inside of the turbo-molecular pump 1 is connected in series to the dry pump 2 at the next stage, it has a negative pressure, and the sublimation temperature of this AlCl ₃ at the atmospheric pressure in the turbo-molecular pump 1 is set to 50 in normal use. If the temperature is around 0 ° C., the temperature of the water flowing from the dry pump 2 into the water jacket 1 c of the turbo-molecular pump 1 has risen to 60 to 70 ° C., and the inside of the pump is entirely raised to a temperature close to this hot water.
For this reason, the ratio of AlCl ₃ becoming a solid phase becomes extremely small, and most of the gas passes through this turbo-molecular pump 1 in a gaseous state, and flows out to the exhaust passage 1 toward the next-stage dry pump 2. become. As a result, by using this exhaust device, it is possible to effectively prevent AlCl ₃ from adhering to and accumulating in the region A near the exhaust port 1b where reaction products are particularly likely to adhere in the turbo molecular pump 1. become. In addition, such a configuration does not cause deterioration or short-circuiting of wiring over many years of use unlike a heater, does not require a control mechanism in the configuration, and introduces problems in terms of maintenance and cost. You don't have to. Further, with such a configuration, when the temperature of the turbo-molecular pump 1 becomes close to the use limit temperature of, for example, about 100 ° C. for some reason (in fact, there is a possibility that the turbo molecular pump 1 has a bearing supporting structure. However, the water flowing from the dry pump 2 into the turbo molecular pump 1 effectively exerts a function as cooling water, and the bearing can be appropriately protected from burning.

In the above embodiment, the turbo-molecular pump of the magnetic bearing type has been described. Further, in the above embodiment, the auxiliary pump is described as a dry pump. However, if there is no problem in use, an oil rotary vacuum pump, a mechanical booster pump, or the like may be used.
In this case, if these pumps are used under the same conditions, the outlet temperature of the cooling water is expected to be slightly lower,
In this case, it is possible to easily cope with the situation by reducing the flow rate. Further, in the above embodiment, the exhaust passage (pipe) 1 between the turbo molecular pump 1 and the auxiliary pump 2 is provided.
When a reaction product such as AlCl ₃ easily adheres, it is also effective to use the present invention to heat this part with cooling water flowing out from the liquid circulation mechanism 2c of the auxiliary pump 2. Others
Various modifications can be made without departing from the spirit of the present invention, such as using a refrigerant other than water as the refrigerant, or a liquid circulation mechanism configured by drawing a pipe. Note that the transition of the cooling water temperature in the embodiment is shown as an example,
It goes without saying that this value differs depending on the performance of the exhaust system and the purpose of use.

[Effect of the Invention] Since the exhaust device of the present invention has the above configuration,
The pressure inside the turbo-molecular pump is made lower than the atmospheric pressure, and the temperature of the base inside the turbo-molecular pump is adjusted with the refrigerant after cooling the auxiliary pump, and the reaction products sublime near the exhaust port inside the pump. This is advantageous in that the bearing can be maintained at a temperature at which the bearing can be effectively cooled. Moreover, as compared with the case where a heater is used, the maintenance cycle is extended and the cost can be reduced.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a schematic circuit diagram, and FIG. 2 is a schematic sectional view of a turbo-molecular pump. 1. Turbo molecular pump 1c Liquid circulation mechanism (water jacket) 2. Auxiliary pump (dry pump) 2c Liquid circulation water cooling mechanism (water jacket)

Claims (1)

(57) [Claims] 1. An exhaust system comprising a series exhaust system including a turbo-molecular pump and an auxiliary pump through an exhaust system, wherein a liquid circulation mechanism is provided in the auxiliary pump and a liquid is circulated also in a base of the turbo-molecular pump. A mechanism is provided to connect the two liquid circulation mechanisms, and the refrigerant circulated through the liquid circulation mechanism of the auxiliary pump is successively introduced into the liquid circulation mechanism of the turbo-molecular pump to control the temperature near the exhaust port. Exhaust device characterized.