JPH0658258A - Cryopump - Google Patents

Abstract

PURPOSE:To provide a cryopump which can be especially operated continuously for a long time. CONSTITUTION:This cryopump in which a plurality of cold heads 23, 23' arranging cryopanels 24, 24' around the respective heads are arranged in a pumpcase 21, and vacuum is generated by adsorbing gas on the surfaces of the cryopanels cooled by means of the cold heads 23, 23', is constituted so that a plurality of the cold heads 23, 23' are scatteredly provided around the suction port 30a of a turbo molecular drag pump 30 received in the pump case 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryopump, and more particularly to a cryopump which can be continuously operated for a long time.

[0002]

2. Description of the Related Art Next, a conventional cryopump will be described with reference to FIG. FIG. 2 is a schematic side sectional view of a main part of a conventional cryopump.

As shown in FIG. 2, a conventional cryopump has a cylindrical pump case 11 connected to a vacuum chamber 10 and a refrigerating unit for cooling helium gas compressed and supplied from a compressor (not shown). Machine 12, a cold head 13 arranged in the pump case 11 and internally expanding helium gas supplied from the refrigerator 12 to self-cool it, and a cryopanel 14 arranged around it to a cryogenic temperature. , Pump case 11
Roughing pump 15, vacuum chamber 10 and pump case communicating inside
The opening and closing valve 16 for opening and closing the connection between 11 is included.

Therefore, after the roughing pump 15 is operated with the open / close valve 16 open to evacuate the interior of the pump case 11 and the vacuum chamber 10, respectively, a compressor (not shown)
When the cryopanel 14 is operated to cool the cryopanel 14 via the refrigerator 12 and the cold head 13, gas is adsorbed on the surface of the cryopanel 14, and the insides of the pump case 11 and the vacuum chamber 10 are extremely vacuumed. (Pressure is below 10 ^-9 Torr).

[0005]

By the way, as described above, the cryopump is a storage pump, that is, a vacuum pump is formed by depositing gas molecules on the surface of the cryopanel 14.

Therefore, in the cryopump, when the deposit (not shown) on the surface of the cryopanel 14 reaches a certain limit amount, the cryopanel 14 is regenerated, that is, the deposit is vaporized and the roughing pump 15 is used. It is essential to release it into the atmosphere.

Regeneration of the cryopanel 14 usually requires about 10 hours in order to evaporate the deposit by raising the temperature of the cryopanel 14 at an extremely low temperature to around room temperature with the opening / closing valve 16 closed.

[0008] Such a regeneration cycle depends on many factors such as the volume of the vacuum chamber 10 and the type of gas, but in many cases it is performed every 1 week to 10 days. Therefore, the vapor deposition apparatus or the like constructed by adopting such a cryopump has to be interrupted for about 10 hours every one week to ten days.

The present invention has been made to solve such a problem, and an object thereof is to provide a cryopump capable of continuous operation for a long time.

[0010]

As shown in FIG. 1, for the above-mentioned purpose, a plurality of cold heads around which cryopanels are arranged are arranged in a pump case, and a cryopanel cooled by the cold heads is provided. In a cryopump that creates a vacuum by adsorbing gas on its surface, a plurality of cold heads 23, 23 'are scattered around the inlet 30a of the turbo molecular pump 30 housed in the pump case 21. It is achieved by a cryopump characterized by the above.

[0011]

In the cryopump of the present invention, for example,
Even if another cryopanel 24 cooled by the cold head 23 is regenerated while the cryopanel 24 'is cooled by the cold head 23', the turbo having the ultimate vacuum degree similar to that of the conventional cryopump described with reference to FIG. Molecular pump
The gas generated from the cryopanel 24 (gas generated by vaporizing the deposits on the surface of the cryopanel 24) is discharged to the outside of the pump case 21 by operating the 30 during the regeneration work of the cryopanel 24 '. .

Therefore, by alternately performing such a regenerating operation for the cold heads 23 and 23 ',
The cryopump of the present invention can be continuously operated for a long period of time.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cryopump according to an embodiment of the present invention will be described below with reference to FIG. FIG. 1 is an explanatory view of a cryopump according to an embodiment of the present invention, and FIG.
Is a schematic side sectional view of the main part of the cryopump, FIG. 1 (b)
[Fig. 3] is a plan sectional view of a cryopump.

In FIG. 1 (a), 21 is a pump case connected to the vacuum chamber 20 and the like, and 22 and 22 'are a plurality (for example, two) of refrigerating units for cooling helium gas compressed by a compressor (not shown). 23, 23 ′ are installed around the turbo molecular pump 30 in the pump case 21, and a plurality of helium gas supplied from the refrigerators 22 and 22 ′ are adiabatically expanded to a cryogenic temperature (for example, two 2) cold head, 24, 24 'cold head
A cryopanel that is cooled to an extremely low temperature by 23, 23 'and adsorbs gas on the surface, 25 is a baffle that is arranged in the pump case 21 and is cooled by liquid nitrogen, 26 is a roughing pump, and 27 is a vacuum. An on-off valve that alternately opens and closes the tank 20 and the pump case 21, and 31 is a motor and 32
Is a rotating shaft connected to the motor 31, 33 is a rotating disk that is attached to the rotating shaft 32, 34 is a concentric rotor blade fixed to the front and back surfaces of the rotating disk 33 (see FIG. 1 (b)), 35, 35 'is a fixed disc, 36
Is a concentric fixed blade fixed to the surface of the fixed disk (Fig. 1
(See (b)).

The motor 31, the rotary shaft 32, the rotary disc 33,
The rotor blades 34, the fixed disks 35, 35 ′ and the fixed blades 36, 36 ′ are components of the turbo molecular pump 30. The cryopump according to the embodiment of the present invention configured as described above supplies the helium gas cooled by the refrigerators 22 and 22 ′ to the cold heads 23 and 23 ′ with the open / close valve 27 opened during the normal operation. The cold heads 23 and 23 'cool the cryopanels 24 and 24' to an extremely low temperature by adiabatically expanding the helium gas and self-cooling.

The cryopanels 24, 24 ′ thus cooled to an extremely low temperature adsorb gas on their surfaces, and the inside of each of the pump case 21 and the vacuum chamber 20 becomes an extremely high vacuum of about 10 ⁻⁹ Torr. To do.

By the way, in the cryopump according to the embodiment of the present invention, when the deposits adsorbed on the surfaces of the cryopanels 24, 24 'reach a certain limit, the cryopump of the conventional cryopump described with reference to FIG. Similar to the cryopanel 14, a work of vaporizing the deposit and discharging it to the outside of the pump case 21, that is, a regenerating work is required.

Further, in the cryopump of the embodiment of the present invention, although the amount of the deposits adsorbed on the respective surfaces of the cryopanels 24, 24 'is considerable, the cryopanels 24, 24''Is capable of continuous operation for a long time by alternately performing regeneration work when it is functioning normally.

For example, in order to regenerate the cryopanel 24, first, the motor 31 of the turbo molecular pump 30 is started to rotate the rotary shaft 32 and the rotary disc 33 to move the moving blade 34 in FIG. 1 (b). As shown, it rotates in the direction of arrow R, and temporarily stops the supply of the lithium gas from the refrigerator 22 to the cold head 23.

The temperature of the cold head 23 whose supply of helium gas has been temporarily stopped from the refrigerator 22 rises, so that the temperature of the cryopanel 24 also gradually rises, and the deposits accumulated on the surface thereof gradually. Is vaporized into a gas (not shown) and diffuses into the pump case 21.

The gas that has diffused into the pump case 21 and has reached the exhaust port 30a of the turbo molecular pump 30, that is, the periphery of the moving blade 34 rotating at high speed, has the moving blade 34 and the fixed blade 36 of the turbo molecular pump 30. The space B, B ′ around the rotary shaft 32 is reached while being compressed by.

Then, the gas that has reached the space B is
After passing through the discharge hole 32a passing from the top surface of 32 to the outer peripheral surface thereof and joining with the gas in the space B ', it is discharged into the atmosphere or the like via the roughing pump 26.

The gas leaving the surface of the cryopanel 24 and heading toward the vacuum chamber 20 is trapped by the baffle 25 which is placed in the pump case 21 and cooled by liquid nitrogen or the like, so that the vacuum chamber 20 is closed. There is almost no backflow.

After the vaporization (removal) of the deposits on the surface of the cryopanel 24 is completed in this way, when the supply of the helium gas from the refrigerator 22 to the cold head 23 is restarted, the cryopanel 24 is cooled to a temperature of about cryogenic temperature. Next, the adsorption of gas is started.

As described above, in the cryopump of the embodiment of the present invention, when the cryopanel 24 is being regenerated, the cryopanel 24 'evacuates the vacuum chamber 20 and when the cryopanel 24' is regenerated. Since the interior of the vacuum chamber 20 can be evacuated by the cryopanel 24, continuous operation for a long time becomes possible.

[0026]

As described above, the present invention makes it possible to provide a cryopump capable of continuous operation for a long time.

Therefore, if the cryopump of the present invention is used to construct a vacuum vapor deposition apparatus or the like, its operating rate will be greatly improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a cryopump according to an embodiment of the present invention,

FIG. 2 is a side sectional view schematically showing a main part of a conventional cryopump,

[Explanation of symbols]

 20, vacuum tank, 21, pump case, 22,22 ', refrigerator, 23,23', cold head, 24,24 ', cryopanel, 25, baffle, 26, roughing pump, 27 is an opening / closing valve, 30 is a turbo molecular pump, 30a is an exhaust port, 31 is a motor, 32 is a rotating shaft, 33 is a rotating disk, 34 is a moving blade, and 35 and 35 'are fixed. The disks, 36 and 36 ', are fixed wings.

Claims (1)

[Claims] 1. A cryopump in which a plurality of cold heads around which a cryopanel is arranged are arranged inside a pump case, and a gas is adsorbed on the surface of the cryopanel cooled by the cold head to create a vacuum, A plurality of cold heads (23, 23 ') are installed in the inlet (30) of the turbo molecular pump (30) housed in the pump case (21).
A cryopump characterized by being scattered around a).