JPH051665A - Vacuum pump - Google Patents

Abstract

PURPOSE:To provide a cryogenic pump which can lengthen the processing period of reactivating treatment as the condition of molecule arresting is saturated. CONSTITUTION:This vacuum pump is constituted to be furnished with an absorbing panel 8 made of hydrogen absorbent metal for arresting hydrogen. The hydrogen absorbent metal is composed of palladium and of titanium nickel alloys or composed of lanthanum nickel alloys. Other than the above, the pump is made up of a pump inlet port 1, buffles 3, a cold head second step (about 100K) 4, a cold head first step (about 4.2K) 5, and of an absorbing panel 7 identical to one used as in the past.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump which has a surface cooled to an extremely low temperature and condenses and captures gas molecules therein to exhaust the inside of a container.

The above vacuum pump is called a cryopump and realizes a degree of vacuum of about 10 ^-8 Torr, and is used, for example, for exhausting an aluminum sputtering apparatus used for manufacturing a semiconductor device.

Since the exhaust capacity decreases as the condensation trap becomes saturated, it is necessary to regenerate the gas at an appropriate cycle, and it is desirable to extend the cycle in order to improve the operating rate of the apparatus used. ing.

[0004]

2. Description of the Related Art FIG. 3 is a schematic sectional view of a conventional cryopump. In FIG. 3, 1 is a pump inlet, 2 is a shield, 3 is a baffle, 4 is a cold head second stage, 5 is a cold head first stage, and 6 is a compressor.

The pump inlet 1 is connected to a container of a device that requires ultra-high vacuum exhaust, such as the aluminum sputtering device. Cold head 2nd stage 4 is about 100K
In addition, the cold head first stage 5 is cooled to about 4.2K. This cooling is performed by liquid helium sent from the compressor 6.

The surface of the baffle 3 condenses water vapor and the like, and the cooling surface of the cold head second stage 4 contains nitrogen, oxygen,
Argon and the like, and the cooling surface of the first stage 5 of the cold head captures hydrogen, neon, helium and the like, and the inside of the container of the above apparatus is evacuated from the pump inlet 1 to a vacuum degree of about 10 ^-8 Torr.

By the way, in the cryopump that exhausts air in this way, the exhaustion capacity is reduced as the condensation trapping is limited and it becomes saturated, so it is necessary to perform regeneration processing at an appropriate cycle. The regeneration process is a process for removing the molecules that have been condensed and trapped, and is performed by returning the condensed and trapped portion to room temperature and purging with nitrogen gas.

In the conventional example, as shown in the partial sectional view of FIG. 4, the sorption panel 7 forming the cooling surface of the first stage 5 of the cold head has a copper plate 7a plated with nickel 7b and activated carbon 7c on its surface. It is configured by adhesion, and activated carbon 7c captures molecules such as hydrogen. And that molecular capture is baffle 3
And, the saturated state is reached earlier than the condensation capture of the molecules in the second stage 4 of the cold head.

Therefore, in the reproducing process, it is necessary to determine the processing cycle corresponding to the period in which the first stage 5 of the cold head reaches the saturated state. At present, the cycle is quite short, for example, once every 1 to 2 weeks.

[0010]

However, it takes about half a day for the above-mentioned regeneration process. Therefore, the conventional cryopump has a problem of lowering the operating rate of the device using the cryopump.

In order to improve the operating rate, it is sufficient to extend the processing cycle of the regeneration processing. Therefore, the present invention relates to a vacuum pump, in particular, a cryopump, and an object thereof is to make it possible to extend the treatment cycle of the regeneration treatment accompanied by the saturation of the molecular trap.

[0012]

In order to achieve the above object, the vacuum pump of the present invention has a surface which is cooled to an extremely low temperature and condenses and traps gas molecules therein to exhaust the inside of the container. It is characterized by having a sorption panel made of a hydrogen storage metal for capturing hydrogen.

The hydrogen storage metal may be palladium, titanium-nickel alloy or lanthanum-nickel alloy.

[0014]

In the conventional example, the trapping of molecules on the sorption panel 7 is saturated immediately before, so that the processing cycle of the regeneration processing is regulated. Moreover, hydrogen is overwhelmingly predominant among the molecules captured by the sorption panel 7. Therefore, if a sorption panel capable of capturing a large amount of hydrogen is provided, the period until the saturated state is reached is extended and the processing cycle of the regeneration process can be extended.

Since the hydrogen storage metal made of palladium, titanium-nickel alloy or lanthanum-nickel alloy adsorbs hydrogen at low temperature and absorbs the adsorbed hydrogen inside and releases the hydrogen at room temperature, a large amount of the above hydrogen is produced. A sorption panel that can be trapped in is realized by using this hydrogen storage metal.

[0016]

Embodiments of the vacuum pump according to the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view of the embodiment, and FIG. 2 is a partial cross-sectional view of a sorption panel provided in the embodiment, and the same reference numerals denote the same objects throughout the drawings.

In FIG. 1, this embodiment is a cryopump in which a sorption panel 8 is newly added to the conventional example described in FIG. The sorption panel 8 is made of palladium, titanium-nickel alloy or lanthanum-nickel alloy and has a hydrogen absorbing metal, and the surface remains as a bare metal. The cooling surface of the head 5 is formed.

The sorption panel 8 cooled to about 4.2K
As shown in FIG. 2, hydrogen adsorbs hydrogen near the surface on the surface and adsorbs the adsorbed hydrogen inside. In FIG. 2, H ₂ indicates hydrogen near the surface, Had indicates hydrogen adsorbed on the surface, and Hab indicates hydrogen absorbed inside. Hydrogen Hab is
The metal hydride is formed by the exothermic reaction and is preserved in the sorption panel 8. The heat generated at that time is absorbed by helium that cools the first stage 5 of the cold head. Therefore, the sorption panel 8 can capture an extremely large amount of hydrogen.

Along with this, the rate of trapping hydrogen in the sorption panel 7 is reduced, and the period until the cold head first stage 5 reaches a saturated state is extended. As a result, in the example, the processing cycle of the reproduction process can be extended as compared with the conventional example.

As in the case of the conventional example, the regeneration treatment is performed by returning the condensation trap portion to room temperature and purging with nitrogen gas, but the required time can be greatly shortened.
This is because the sorption panel 8 spontaneously releases hydrogen stored as a metal hydride by an endothermic reaction at normal temperature.

[0021]

As described above, according to the present invention, a vacuum pump (cryopump) having a surface cooled to an extremely low temperature and condensing and capturing gas molecules therein and exhausting the inside of a container is provided. Is saturated, the processing cycle of the regeneration processing can be extended, and the operation rate of the apparatus using the pump can be improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example.

FIG. 2 is a partial sectional view of a sorption panel provided in an embodiment.

FIG. 3 is a schematic sectional view of a conventional example.

FIG. 4 is a partial sectional view of a sorption panel in a conventional example.

[Explanation of symbols]

1 pump inlet 2 shield 3 baffles 4 second cold head 5 Cold head 1st stage 6 compressor 7 Conventional sorption panel 7a copper plate 7b plated nickel 7c bonded activated carbon 8 Additional newly installed sorption panel

Claims (2)

[Claims] 1. A sorption panel comprising a hydrogen storage metal for trapping hydrogen, which is a vacuum pump having a surface cooled to an extremely low temperature and condensing and trapping gas molecules to exhaust the inside of the container. ) Is equipped with the vacuum pump. 2. The vacuum pump according to claim 1, wherein the hydrogen storage metal is palladium, titanium-nickel alloy or lanthanum-nickel alloy.