JPH0549805A - Low temperature trap for vacuum equipment - Google Patents

Abstract

PURPOSE:To provide the subject equipment in which plural low temp. traps are cooled by one refrigerator to make the installation small-sized and low- priced one and little vibration is transmitted to the vacuum equipment and there is no danger of environmental disruption. CONSTITUTION:In a low temp. trap 6 equipped with a low temp. part 5 for condensing steam, etc., in a vacuum chamber 2 and its exhaust passage 1, a heat pipe 8 cooled at one end by a small-size helium refrigerator 6 is connected with the low temp. part 5 at the other end to cool it. Plural heat pipes are cooled at one side ends by one small-size refrigerator and the low temp. traps connected with the heat pipes at the other side ends are simultaneously cooled. Thereby, the vibration by the small-size refrigerator is hardly transmitted to the low temp. part of the low temp. trap to decrease the vibration of the vacuum equipment, and since plural low temp. traps are cooled by one small-size refrigerator 6, a safe, small-size, low temp. trap which is low-priced and does not disrupt environment is obtained and liquid nitrogen does not need replenishing and running cost is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum device low temperature trap for condensing and collecting water vapor in a vacuum chamber of a vacuum device, oil vapor in an exhaust passage extending from the vacuum chamber to a vacuum pump, and the like.

[0002]

2. Description of the Related Art An oil diffusion pump or a turbo molecular pump does not create a vacuum state by condensing and collecting gas molecules in a low temperature part like a cryopump, but moves by eliminating gas molecules to create a vacuum state. Because it is produced, the pumping speed for water is much inferior to the cryopump. Further, when the vacuum chamber is evacuated by the oil diffusion pump, oil vapor may flow back into the vacuum chamber and contaminate the vacuum chamber. Therefore, when vacuum evacuation is performed by an oil diffusion pump or a turbo molecular pump, a low temperature trap having a low temperature part cooled by liquid nitrogen, a small helium refrigerator or a Freon refrigerator is provided at its intake port, and water vapor or oil vapor is It condenses and collects in a low temperature trap to improve the exhaust speed for water as much as a cryopump and prevent the backflow of oil vapor. An example of a low temperature trap using liquid nitrogen is as shown in FIG. 1, and in this case, the low temperature trap g is in an exhaust passage c to an oil diffusion pump b connected to a vacuum chamber a,
It is composed of a low temperature part f made of a baffle cooled by liquid nitrogen e in the tank d, prevents the steam in the vacuum chamber a from condensing in the low temperature part f, and prevents the steam from flowing into the oil diffusion pump b. The oil vapor generated by the oil diffusion pump b is condensed in the low temperature part f so as not to flow back into the vacuum chamber a.
When a small helium refrigerator is used, as shown in FIG. 2, the low temperature part f is cooled in the first stage i of the small helium refrigerator h such as the GM cycle and the Solvay cycle to cool the small helium refrigerator. The low temperature part f may be cooled by a Freon refrigerator provided in place of the refrigerator h. Further, in order to enhance the effect of removing water vapor, as shown in FIG. 3, a low temperature portion f of a coiled copper pipe extending from the Freon refrigerator j is also provided in the vacuum chamber a. In these cases, when the low temperature trap g is cooled to 150 K (-123 ° C.) or less, the vapor pressure of water condensed in the low temperature part f is 10
It becomes -8 Torr or less, and the operation of exhausting water can be performed and at the same time the oil vapor can be exhausted.

[0003]

A device provided with a low temperature trap cooled with liquid nitrogen as described above consumes liquid nitrogen, resulting in high operating cost and labor for replenishing liquid nitrogen. Maintenance is troublesome. Also, in the case of cooling the low temperature part with a small helium refrigerator, the small helium refrigerator directly cools the low temperature part.Therefore, when cooling multiple low temperature parts, it is necessary to provide multiple small helium refrigerators. However, there is a drawback that the equipment cost is high, and since a refrigerator with large vibration is directly attached to the vacuum device, the vibration is transmitted to the vacuum device, which is not preferable. Furthermore, the use of the Freon refrigerator should be restricted from the viewpoint of preventing the destruction of the global environment, and in order to obtain a temperature of about 150 K with this refrigerator, two-stage compression or three-stage compression is necessary, and the refrigerator is large. However, it is not suitable for high vacuum below 10-9 Torr.

According to the present invention, a plurality of low temperature traps can be cooled by one refrigerator, the equipment can be made small and inexpensive, and the low temperature traps for a vacuum device are small in vibration transmission to the vacuum device and there is no fear of environmental damage. It is intended to provide.

[0005]

According to the present invention, in a low temperature trap having a low temperature portion for condensing water vapor or the like in a vacuum chamber or its exhaust passage, a heat pipe whose one end is cooled by a small helium refrigerator is provided. The above-mentioned object was achieved by connecting the low temperature part to the end and cooling it.

[0006]

When a vacuum chamber is evacuated to a vacuum by an oil diffusion pump or a turbo molecular pump connected through an exhaust passage, these pumps are inferior in the exhaust rate of water vapor and oil vapor, and a low temperature trap must be provided. In the case of the present invention, the low temperature portion of the low temperature trap provided in the vacuum chamber or the exhaust passage is connected to the small helium refrigerator via a heat pipe, and the low temperature of 70 to 150 K of the small helium refrigerator is the low temperature trap. Even if there are multiple low temperature traps, one small helium refrigerating unit can be used because it condenses water vapor in the vacuum chamber or exhaust passage and oil vapor that flows back into the vacuum chamber from the steam pump to the low temperature unit. Each cold trap can be connected to the machine via a heat pipe to cool them simultaneously. Further, the small helium refrigerator has a large vibration, but since the small helium refrigerator can be provided at a remote position apart from the low temperature portion via a relatively flexible heat pipe,
Vibration of the vacuum chamber provided with the low temperature trap and the exhaust passage is reduced, and stable processing work can be performed in the vacuum device.

[0007]

EXAMPLE An example of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an exhaust passage connected to an oil diffusion pump or a vacuum pump 3 of a turbo molecular pump to exhaust the inside of a vacuum chamber 2 of a vacuum device such as a sputtering device. 1 is provided with a low temperature part 5 made of aluminum or the like, which comprises a baffle of a low temperature trap 4. It is the same as the conventional low temperature trap 4 that the low temperature part 5 is cooled by the small helium refrigerator 6 of the GM cycle or the solve cycle that constitutes the low temperature trap 4, but in the case of the present invention, the low temperature part 5 is used. Is connected to the first stage 7 of the small helium refrigerator 6 via a heat pipe 8, and one end of the heat pipe 8 is connected to the first stage 7 at, for example, 35 to 150K.
When cooled to the other end, the other end takes heat from the low temperature part 5,
The low temperature section 5 is cooled to a temperature of approximately the same level. The small helium refrigerator 6 is attached so that the first stage 7 is housed inside a vacuum container 9 fixed to an appropriate machine frame, and a flexible vacuum heat insulating tube 10 is provided around a heat pipe 8 extending from the vacuum container 9. I tried to cover it. Reference numeral 11 is a partition that shuts off the inside of the vacuum heat insulating tube 10 so that the vacuum container 9 and the exhaust passage 1 do not communicate with each other. Also, 12 is the first stage 7
It is a temperature controller equipped with a thermocouple 13 attached to and a heater 14 for heating the first stage 7. The heat pipe 8
5, the metal pipe 8a is provided with a wire net or a porous metal wick 8b on its inner wall surface, and a space 8c therein is filled with a working fluid such as nitrogen gas and hermetically sealed. ..

The operation of the embodiment shown in FIGS. 4 and 5 will be described. When the insides of the vacuum chamber 2 and the vacuum container 9 are in a vacuum state and the whole is at room temperature, the operation of the small helium refrigerator 6 is performed. After the start, when the first stage 7 is cooled to about 110K, the end A side of the heat pipe 8 that contacts the first stage 7 is also cooled to the same temperature, and the nitrogen gas inside the end A side. Liquefaction begins with. Then, the generated liquid nitrogen flows in the wick 8b shown in FIG. 5 toward the opposite end B side due to surface tension, evaporates at a high temperature portion in the middle, and the vapor passes through the space 8c to the A side. Repeat liquefaction with. When the generated liquid nitrogen reaches the B side of the heat pipe 8, the low temperature portion 5 of the low temperature trap 4 that contacts the B side is cooled. The low temperature section 5
Due to the heat load, the nitrogen evaporated on the B side passes through the space 8c and is reliquefied on the A side, and the low temperature part 5 is cooled to about 70 to 80K by repeating this. When the low temperature part 5 is cooled, water vapor passing through the exhaust passage 1 and oil vapor flowing back from the pump 3 to the vacuum chamber 2 are condensed on the low temperature part 5. When the temperature on the A side of the heat pipe 8 drops below 70K,
Nitrogen is solidified, liquid nitrogen is exhausted on the B side, the inside of the heat pipe 8 becomes a vacuum state, and the heat transfer capability is lost.
To prevent this, the temperature of the first stage 7 is 70K.
When the temperature falls below, the temperature controller 12 energizes the heater 14 and controls the temperature of the first stage 7 to 70 to 110K.

As shown in FIG. 6, in a vacuum apparatus having a plurality of vacuum chambers 2 each having an exhaust passage 1, a low temperature trap 4 provided in each exhaust passage 1 is provided as one small helium refrigerator. It can be cooled at the same time by the machine 6. In this case, the same number of heat pipes 8 as the low temperature traps 4 are prepared, and one end of each heat pipe 8 is thermally connected to the first stage 7 of one small helium refrigerator 6.

In order to remove water vapor by the low temperature trap 4 inside the vacuum chamber 1 and the vacuum container, as shown in FIG. A low temperature portion of the metal plate 15 is provided, and the metal plate 15
As in the case of the low temperature trap, the heat pipe 8
It is also possible to connect the small helium refrigerator 6 via. In this case, since water vapor or oil vapor generated in the vacuum chamber 1 can be condensed in the metal plate 15,
The inside of the vacuum chamber 1 and the like is kept clean. Inside the first stage 7 of the small helium refrigerator 6, a reciprocating piston is provided, and vibration during operation is relatively large, but the small helium refrigerator 6 is directly attached to the low temperature section 5. However, since the refrigerator 6 can be provided in a remote location, it is difficult for the vibration to be transmitted to the low temperature section 5 and the vacuum device.

[0011]

As described above, according to the present invention, the low temperature portion of the low temperature trap is connected to the other end of the heat pipe whose one end is cooled by the small helium refrigerator to cool it. The vibration of the small helium refrigerator is less likely to be transmitted to the low temperature part of the low temperature trap, the vibration of the vacuum device can be reduced, and multiple low temperature traps can be cooled by one small helium refrigerator, which is inexpensive and damages the environment. It is possible to obtain a safe, small-sized, low-temperature trap, and it is unnecessary to replenish liquid nitrogen.

[Brief description of drawings]

FIG. 1 is a cutaway side view of a conventional low temperature trap using liquid nitrogen.

FIG. 2 is a cutaway side view of a low temperature trap using a conventional small helium refrigerator.

FIG. 3 is a cutaway side view of a low temperature trap using a conventional Freon refrigerator.

FIG. 4 is a cutaway side view of an embodiment of the present invention.

FIG. 5 is an enlarged sectional view of the heat pipe.

FIG. 6 is a cutaway side view of another embodiment of the present invention.

FIG. 7 is a cutaway side view of still another embodiment of the present invention.

[Explanation of symbols]

 1 Exhaust Passage 2 Vacuum Chamber 3 Vacuum Pump 4 Low Temperature Trap 5 Low Temperature Section 6 Small Helium Refrigerator 8 Heat Pipe

Claims (2)

[Claims] 1. A low temperature trap having a low temperature part for condensing water vapor or the like in a vacuum chamber or its exhaust passage, wherein the low temperature part is connected to the other end of a heat pipe whose one end is cooled by a small helium refrigerator. A low temperature trap for a vacuum device, characterized by cooling it. 2. A small helium refrigerator cools the ends of a plurality of heat pipes, and simultaneously cools the low temperature traps connected to the other ends of the heat pipes. A low temperature trap for a vacuum device as described in.