JP3061011B2 - Cryopump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement of a cryopump.

[0002]

2. Description of the Related Art Conventionally, a cryopump as shown in FIG. 2 has been used for evacuation of a vacuum device used for manufacturing a semiconductor or vapor deposition of a lens. In this cryopump, a two-stage expansion refrigerator 1 having two-stage expansion cylinders 2 and 3 is used.

A second cryopanel 7 stacked in multiple stages is attached to a heat stage (second heat stage) 5 of a second-stage (final-stage) expansion cylinder 3. Further, the center of the bottom surface of a fast cryopanel 6 which has a bottomed cylindrical shape and functions as a radiation shield is attached to a heat stage (fast heat stage) 4 of the first-stage expansion cylinder 2.

[0004] The fast cryopanel 6 and the baffle 8 attached to the tip of the fast cryopanel 6 form a chamber.
(Not shown) to condense and exhaust water vapor. On the other hand, the second cryopanel 7 condenses the nitrogen gas and the argon gas in the chamber which cannot be exhausted by the fast cryopanel 6, and the hydrogen gas is condensed by the second cryopanel 7.
It is adsorbed and exhausted by activated carbon (not shown) attached to the surface.

In order to achieve the radiation shielding function of the fast cryopanel 6, it is necessary to control the temperature of the fast cryopanel 6 in the range of 50K to 150K. This temperature range is set for the following reasons.
That is, the reason why the temperature is set to 150K or lower is to condense and exhaust the steam as described above. However, when the temperature becomes 50 K or lower, the argon gas is also condensed, and the condensed argon gas is released during the steady operation.

[0006] The second cryopanel 6 50
To facilitate temperature management in the range of K to 150K,
Usually, the second cryopanel 6 is subjected to a surface treatment such as a different color painting or a mirror finish.

[0007]

As described above, in the cryopump, the exhaust of nitrogen gas, argon gas and hydrogen gas by the cryopanel at the last stage and the exhaust of water vapor by cryopanels other than the final stage are smoothly performed. Therefore, it is necessary to control the temperature of the cryopanel other than the last stage in the range of 50K to 150K.

Therefore, in the conventional cryopump, as shown in FIG. 2, a two-stage (multi-stage) expansion refrigerator 1 is used, and the second cryopanel 7 is connected to the second heat stage 5 of the second expansion cylinder 3. On the other hand,
The fast cryopanel 6 functioning as a radiation shield is attached to the fast heat stage 4 of the first-stage expansion cylinder 2. The fast cryopanel 6 has a complicated configuration in which surface treatment such as different color painting or mirror finishing is performed. Therefore, the conventional cryopump has a problem that the cost is high.

Further, as described above, the temperature control of the fast cryopanel 6 is a complicated control that takes into account the surface state of the fast cryopanel 6 and the environmental temperature, so that accurate temperature control can be performed. There is another problem.

An object of the present invention is to provide an inexpensive cryopump in which the temperature of the radiation seal can be easily controlled.

[0011]

According to one aspect of the present invention, there is provided a cryopump having a single-stage cryogenic refrigerator, a cryopanel mounted on a heat stage of the cryogenic refrigerator, With a cylindrical portion, a radiation shield surrounding the cooling cylinder and the cryopanel of the cryo refrigerator in the cylindrical portion, and having a bottom and a cylindrical portion, the bottom portion is attached to the cryo refrigerator, It is characterized by comprising an enclosure surrounding the cylindrical portion of the radiation shield body with the cylindrical portion, and cooling means for cooling the radiation shield body.

According to the above configuration, the single-stage cryogenic refrigerator is driven to cool the cryopanel mounted on the heat stage to a temperature of 50K or less. On the other hand, the radiation shield is cooled to a temperature range of 50K to 150K by the cooling means. In this way, by cooling the radiation shield independently of the cryopanel, the radiation shield temperature of the radiation shield can be easily and accurately maintained within the optimum temperature range of 50K to 150K.
Furthermore, an inexpensive cryopump can be obtained by cooling the cryopanel with a single-stage cryogenic refrigerator.

A cryopump according to a second aspect of the present invention is the cryopump according to the first aspect of the present invention.
The cooling means is a Peltier element.

According to the above configuration, since the cooling means is composed of a Peltier element, a small and inexpensive cryopump can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a longitudinal sectional view of a cryopump according to the present embodiment. In the cryopump according to the present embodiment, a single-stage expansion refrigerator 11 having a single-stage expansion cylinder 12 is used.

The center of the bottom 15 of the second cryopanel 14 having a substantially cylindrical shape with a bottom is attached to the heat stage 13 of the expansion cylinder 12 of the single-stage expansion refrigerator 11. And the second cryopanel 1
Activated carbon 17 for adsorbing hydrogen gas is attached to the inner peripheral surface of the cylindrical portion 16 of No. 4.

A flange 19 is provided at an end on the expansion cylinder 12 side of the cylindrical drive portion 18 in which the motor and the like (not shown) in the single-stage expansion refrigerator 11 are housed.
An enclosure 20 is attached to the collar 19. The enclosure 20 has a bottomed cylindrical shape,
A hole 22 is provided at the center of the bottom 21. And
When the enclosure 20 is attached to the single-stage expansion refrigerator 11, the expansion cylinder 12 of the single-stage expansion refrigerator 11 is inserted into the hole 22, and the enclosure 20 is arranged so as to surround the expansion cylinder 12 with the cylindrical portion 23. You. The periphery of the hole 22 is the flange 1 of the single-stage expansion refrigerator 11.
9 and fixedly attached.

A fast cryopanel 24 as the radiation shield is provided between the enclosure 20 and the second cryopanel 14. This fast cryopanel 24 has a bottomed cylindrical shape,
A hole 26 is provided at the center of the bottom 25. The fast cryopanel 24 having the above configuration is arranged such that the expansion cylinder 12 of the single-stage expansion refrigerator 11 is inserted into the hole 26 of the bottom part 25, and the cylindrical part 27 and the cylindrical part 16 of the second cryopanel 14 are opposed to each other. . Then, the bottom 25 of the fast cryopanel 24 is fixed to the bottom 21 of the enclosure 20 via the Peltier element 28.

The Peltier element 28 absorbs heat of the fast cryopanel 24 and emits it to the enclosure 20 side when a current flows in a certain direction through a joint between two metals. And it has the characteristic that the amount of heat absorbed changes according to the magnitude of the flowing current. Therefore, in the present embodiment, the cylindrical portion 2 of the fast cryopanel 24
The temperature of 7 is measured by the thermistor 29, and the controller 30 controls the value of the current supplied from the power supply 31 to the Peltier device 28 based on the measured temperature. In this way, the temperature of the fast cryopanel 24 is positively increased from 50K to 15K.
Keep it in the range of 0K.

The cryopump constructed as described above operates as follows. First, the heat stage 13 is cooled by driving the single-stage expansion refrigerator 11 to expand the refrigerant gas in the expansion cylinder 12, and the temperature of the second cryopanel 14 is set to 50K or lower. Next, the controller 30
Is operated, and based on the temperature of the cylindrical portion 27 of the fast cryopanel 24 measured by the thermistor 29, the temperature of the fast cryopanel 24 and the baffle 32 attached to the tip thereof is kept in the range of 50K to 150K. So that the current value supplied from the power supply 31 to the Peltier element 28 is controlled.

Thus, the radiation shield temperature is set to 50K to 1
Fast cryopanel 24 in 50K range
And the baffle 32 attached to the tip of the
Chamber connected to the tip of enclosure 20
The water vapor (not shown) is condensed and exhausted. on the other hand,
Second cryopanel 14 with temperature below 50K
Thereby, the nitrogen gas and the argon gas in the above chamber that cannot be exhausted by the fast cryopanel 24 are condensed,
The hydrogen gas is adsorbed by the activated carbon 17 attached to the second cryopanel 14 and exhausted.

As described above, the cryopump according to the present embodiment cools the second cryopanel 14 on which the activated carbon 17 is adhered by the expansion cylinder 12 of the single-stage expansion refrigerator 11, and functions as a radiation shield. The cryopanel 24 is cooled by the Peltier element 28 independently of the second cryopanel 14. A thermistor 29 is provided on the cylindrical portion 27 of the fast cryopanel 24, and the current supplied to the Peltier element 28 is controlled based on the temperature of the cylindrical portion 27 measured by the thermistor. Therefore, the cryopump in the present embodiment is a fast cryopanel 24
Temperature can be actively controlled, and radiation shield temperature can be reduced to 50K.
It can be easily and accurately controlled within the range of ~ 150K.

In this embodiment, the single-stage expansion refrigerator 11 is used, and the fast cryopanel 2
4 can be realized with a simple configuration that does not require surface treatment such as a different color coating or mirror finishing. Therefore, significant cost reduction can be achieved.

In the above embodiment, the radiation shield temperature of the fast cryopanel 24 is set to 50K to 15K.
A Peltier element 28 is used as means for keeping the temperature in the range of 0K. However, the present invention is not limited to this, and another refrigerator for cooling the fast cryopanel 24 may be used. As such a refrigerator for cooling the fast cryopanel 24, a small / light and inexpensive Stirling refrigerator can be considered. And, for example,
The Stirling refrigerator is controlled by the controller based on the surface temperature of the fast cryopanel 24 measured by the thermistor.

[0025]

As is clear from the above description, in the cryopump according to the first aspect of the present invention, the cryopanel is mounted on the heat stage of a single-stage cryogenic refrigerator, and the cooling cylinder and the cryogenic of the cryogenic refrigerator are mounted in the cylindrical portion. The radiation shield surrounding the panel was cooled by cooling means, and the bottom surrounded the cylinder of the radiation shield with the cylinder of the enclosure attached to the cryo refrigerator, so that the cryopanel and the radiation shield were mutually separated. Can be cooled independently.

Therefore, the cryopanel is heated at a temperature of 5 ° C.
While cooling to below 0K, the temperature of the radiation shield
It can be easily and accurately controlled to be within the optimal range of 0K to 150K. Furthermore, an inexpensive cryopump can be obtained by using a single cryogenic refrigerator for cooling the cryopanel.

In the cryopump according to the second aspect of the present invention, the cooling means is a Peltier element.
A small and inexpensive cryopump can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cryopump according to the present invention.

FIG. 2 is a partial longitudinal sectional view of a conventional cryopump.

[Explanation of symbols]

11: single-stage expansion refrigerator, 12: expansion cylinder, 14: second cryopanel, 17: activated carbon, 19: tsuba, 20: enclosure, 24: fast cryopanel, 28:
Peltier device, 29 ... Thermistor, 3
0: controller, 31: power supply.

Claims (2)

(57) [Claims] 1. A cryo-refrigerator (11) having a single stage, a cryo-panel (14) attached to a heat stage (13) of the cryo-refrigerator (11), and a cylindrical portion (27). A radiation shield body (24) surrounding a cooling cylinder (12) and a cryopanel (14) of the cryogenic refrigerator (11) in a cylindrical portion (27).
A bottom portion (21) and a cylindrical portion (23), and the bottom portion (2
1) is attached to the cryo-refrigerator (11), and the cylindrical portion (23) of the radiation shield body (24) is mounted on the cylindrical portion (23).
And a cooling means (28) for cooling the radiation shield (24). 2. The cryopump according to claim 1, wherein said cooling means is a Peltier device.