JP3024281B2 - Cryopump - Google Patents

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 in which a displacer provided in a cylinder is reciprocated by introducing high-pressure gas and discharging low-pressure gas to obtain a very low temperature.

[0002]

2. Description of the Related Art Conventionally, this type of cryopump is described in, for example, Japanese Patent Application Laid-Open No. 63-259357. As shown in FIG. 5, the conventional cryopump includes a cylinder C having heat stages A and B at a lower end thereof, and a motor housing D attached to an upper end of the cylinder C. , Motor E and the motor E
And a passage block I having an injection passage H for introducing a high-pressure gas and discharging a low-pressure gas by switching the switching valve device G. The cylinder C is provided with a displacer L which has refrigerating units J and K and reciprocates by introducing high-pressure gas into the cylinder C and discharging low-pressure gas.
And the passage block I, the displacer L
Slack piston M interlocking with a predetermined stroke
Are freely reciprocated, the injection / discharge passage H is provided between the passage block I and the motor housing D via a capillary (not shown), and the low-pressure gas passage is provided via a bleed (not shown). Are provided with an intermediate pressure surge volume N, and the surge volume N is communicated through an orifice P to an opposing chamber S facing the action chamber R of the slack piston M.

When the high pressure gas is introduced into the cylinder C by switching the injection / exhaust passage H to the high pressure gas passage by the switching valve device G, the working chamber R of the slack piston M becomes high pressure, and this working chamber The slack piston M and the displacer L move upward due to the pressure difference between R and the opposing chamber S, which is an intermediate pressure, and are introduced into the expansion spaces T, V adjacent to the heat stages A, B. When the gas is filled and the switching valve device G switches the injection / discharge passage H to a low-pressure gas passage and the pressure in the cylinder C and the working chamber R becomes low, the working chamber R and the working chamber R become intermediate pressure. The slack piston M and the displacer L return downward due to the pressure difference between the opposing chamber S and
The expanded low-pressure gas is discharged, and the extremely low temperature is obtained in the heat stages A and B by repeating the introduction and discharge of the high-pressure gas.

When a wafer in a vacuum atmosphere is directly cooled to a very low temperature by the heat stage A using the cryopump configured as described above in, for example, a semiconductor manufacturing apparatus, and the wafer is etched, the wafer is etched. A high-frequency current is applied to generate plasma around the wafer, and the wafer is etched by the plasma.However, the conventional cryopump is not electrically insulated between the ground, so the high-frequency Current flows along the gas pipe connected to the motor housing D to the ground, and the coil coating of the motor E in the switching valve device G is broken. For this reason, when etching the wafer, an electric insulator made of ceramics is laid on the heat stage A, the wafer is placed on the insulator, and a high-frequency current is applied to the wafer. The current is prevented from escaping to the ground through the gas pipe, and the coil coating of the motor E is prevented from being destroyed.

However, when an electric insulator is laid on the heat stage A and a wafer is placed on the insulator as described above, the wafer is cooled via the electric insulator. There is a problem that the cooling effect of the wafer is deteriorated, and a large-sized cryopump is required to cool the wafer to a predetermined cryogenic temperature, so that the initial and running costs are increased accordingly.

The present invention has been made in view of the above problems, and an object of the present invention is to avoid a large pump as a whole while directly cooling a wafer to a very low temperature with a heat stage. The point is to make it possible.

[0007]

In order to achieve the above object, according to the present invention, a cylinder 1 having a heat stage 11 is provided.
And a motor housing 5 mounted on the cylinder 1 via a mounting flange 12, a switching valve device 6 having a motor 61 provided in the motor housing 5, and introduction of high-pressure gas by switching the switching valve device 6. And a passage block 7 having an injection / discharge passage 71 for discharging a low-pressure gas and a displacer 3 which is housed in the cylinder 1 and reciprocates by introducing high-pressure gas into the cylinder 1 and discharging the low-pressure gas. In the cryopump, an electric insulator 24 is interposed between the mounting flange 12 and the motor housing 5 and the passage block 7 is formed of an electric insulator, while the mounting flange 12 and the motor housing 5 are connected to each other. They were joined by means of an electrically insulating structure.

In the cryopump, the motor housing 5 and the valve body 62 of the switching valve device 6 which is in contact with the passage block 7 may be formed of an electrical insulator.
Alternatively, the mounting flange 12 and the passage block 7 are formed of an electric insulator, or the mounting flange 12 and the slack piston 10 interposed between the passage block 7 and the displacer 3 are formed of an electric insulator. May be.

In the cryopump, a first block 7a having a first injection / discharge passage 71a for separating the cylinder 1 and the motor housing 5 and opening the passage block 7 to the cylinder 1 is provided. The first block 7a is divided into a second block 7b having a second injection / discharge passage 71b communicating with the switching valve device 6, and the first block 7a is fixed to the mounting flange 12 of the cylinder 1, and the second block 7b Is fixed to the motor housing 5,
The first and second discharge passages 71a and 71b may be connected by the connecting pipe 30 having an electrically insulating structure.

[0010]

An electric insulator 24 is interposed between the mounting flange 12 for mounting the motor housing 5 to the cylinder 1 and the motor housing 5, and the switching of the switching valve device 6 allows the introduction of high-pressure gas and the supply of low-pressure gas. A passage block 7 having a discharge passage 71 for discharging is formed of an electric insulator,
Furthermore, since the mounting flange 12 and the motor housing 5 are connected by a connecting means having an electric insulating structure, the wafer is directly cooled by the heat stage 11, and the wafer is etched by applying a high-frequency current to the wafer. ,
The high-frequency current can be prevented from escaping to the ground along the gas pipe connected to the motor housing 5 by the electric insulator 24 and the coupling means of the electric insulating structure.
In addition, the passage block 7 can prevent the high-frequency current from escaping to the motor 61 side. Moreover,
Since the wafer can be cooled directly by the heat stage 11, not only the cooling effect of the wafer is high, but also it is not necessary to form the whole pump in a large size.

Further, the motor housing 5 and the valve body 62 of the switching valve device 6 are formed of an electrical insulator, or the mounting flange 12 and the passage block 7 are formed of an electrical insulator, or By forming the mounting flange 12 and the slack piston 10 with an electric insulator, the high-frequency current can be prevented from escaping to the ground through a gas pipe without providing a special electric insulator. Since the motor 61 can be protected from the above, the configuration is very simple and the cost can be reduced.

The cylinder 1 and the motor housing 5
And the passage block 7 is divided into a first block 7a and a second block 7b, and the first and second discharge passages 71a, 71b of these blocks 7a, 7b are connected to an electrically insulating connecting pipe. By connecting at 30, the motor housing 5 can be disposed at an unspecified position away from the cylinder 1 while being insulated, so that even when the space at the pump installation position is small, the cylinder 1 portion It can be arranged at the position.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a cylinder having a heat stage 11 at one end and a mounting flange 12 at the other end. A displacer 3 provided with a vessel 2 is reciprocally movable inside, and the lower end of the displacer 3 faces the expansion space 4.

Reference numeral 5 denotes a connection port 5 for a high-pressure gas pipe and a low-pressure gas pipe.
1, a motor housing mounted on the mounting flange 12 of the cylinder 1 and having a motor 61 and a switching valve device 6 having a valve body 62 rotated by the motor 61. It is decorated.
The motor housing 5 has the connection port 52, a base body 5 a that houses the valve body 62, and a cover body 5 b that has the connection port 51 and houses the motor 61.
And the base body 5a and the cover body 5b.
Are physically connected by a connecting means such as a tightening screw.

Reference numeral 7 denotes a passage block having an injection / discharge passage 71 for introducing high-pressure gas and discharging low-pressure gas by switching the valve element 62 in the switching valve device 6, and a flange 72.
The passage block 7 is interposed between the motor housing 5 and the cylinder 1 so that the flange portion 72 is received by the mounting flange 12. The discharge port 71 which penetrates in the opening direction into the cylinder 1 and extends in the axial direction from the valve seat surface, and the distal end thereof is bent in the radial direction to form the connection port 5.
And a discharge passage 73 communicating with the connection port 52.
The low-pressure gas passage 8 is defined as a passage leading to the switching valve device 6 through the discharge passage 73, and the high-pressure gas passage 9 is defined as a passage extending from the connection port 51 to the switching valve device 6 through a space in the motor housing 5. I have.

A slack piston 10 interlocking with the displacer 3 via a predetermined stroke is provided between the displacer 3 and the passage block 7 in the cylinder 1 so as to freely reciprocate. Capillary (not shown) on base
An intermediate pressure surge volume 20 is provided which communicates with the supply / discharge passage 71 via a bleed (not shown) and communicates with the low pressure gas passage 8 via a bleed (not shown).
Through the orifice 21.
The working chamber 22 is connected to a facing chamber 23 facing the working chamber 22 so that the facing chamber 23 has a predetermined intermediate pressure between a high pressure and a low pressure. When the high-pressure gas is introduced into the cylinder, the displacer 3 moves toward the passage block 7 due to a pressure difference between the high pressure in the cylinder 1 and the intermediate pressure in the opposed chamber 23,
When the supply / discharge passage 71 communicates with the low-pressure gas passage 8 by the switching valve device 6 and the pressure in the cylinder 1 becomes low, the pressure difference between the low pressure in the cylinder 1 and the intermediate pressure in the opposed chamber 23 is reduced. As a result, the displacer 3 moves back toward the heat stage 11 to discharge the low-pressure gas after expansion, and a very low temperature is obtained in the heat stage 11 by repeating the introduction and discharge of the high-pressure gas.

As shown in FIG. 1, a plate-shaped electrical insulator 24 made of ceramics is interposed between the facing surfaces of the mounting flange 12 and the motor housing 5, and the passage block 7 is mainly made of ceramics. On the other hand, the mounting flange 12 and the motor housing 5 are provided with through holes 13 and 53 for coupling, and a headed bolt 25 is inserted through the through holes 13 and 53; Nut 26 screwed to the tip
And a pair of ceramic washers 27 and 28, the one washer 27 is interposed between the head 25a of the bolt 25 and the mounting seat 54 of the motor housing 5, The mounting flange 12 and the motor housing 5 are connected by tightening the nut 26 with the washer 28 interposed between the nut 26 and the end face of the mounting flange 12.
In addition, the through holes 13 and 53 are formed to have a larger diameter than the bolt 25 so that the bolt 25 does not contact. Further, the electric insulator 24 and the washers 27 and 28 may be made of a synthetic resin other than ceramics, such as a fluorine resin, or an electric insulating material other than the resin.

When the cryopump configured as described above is used in, for example, a semiconductor manufacturing apparatus, the wafer is directly cooled by the heat stage 11, and a high-frequency current is applied to the wafer to etch the wafer. The electric insulator 24 and the washers 27 and 28 can prevent the heat stage 11 and the cylinder 1 from escaping to the ground along a gas pipe connected to the motor housing 5, and the high-frequency current can be reduced by the cylinder. The passage block 7 can prevent the flow from 1 through the displacer 3 and the slack piston 10 to the motor 61 side.

In the embodiment described above, the bolts 25, the nuts 26, and the electrically insulating washers 27 and 28 are used as the connecting means for connecting the mounting flange 12 and the motor housing 5. The washer 27, 28 may be eliminated, and the bolt 25 may be formed in an electrically insulating structure.

In the embodiment described above, the electric insulator 2
4 is used to prevent the high-frequency current from escaping to the ground through the gas pipe, but may be configured as shown in FIG. 2 or FIG.

In FIG. 2, the motor housing 5 is formed of an electric insulator made of ceramics, and the valve body 62 contacting the valve seat surface of the passage block 7 is electrically insulated from a synthetic resin such as a fluorine resin. It was formed by the body. In this case, the high-frequency current applied to the wafer can be prevented from escaping to the ground along the gas pipe by the motor housing 5, and the high-frequency current flowing to the motor 61 side can be prevented by the valve body. 62
This can be prevented.

The motor housing 5 and the valve body 62
Instead of being formed of an electric insulator, the mounting flange 12 and the passage block 7 shown in FIG. 2 may be formed of an electric insulator such as ceramics or synthetic resin, respectively, or the mounting flange 12 and the slack piston may be formed. 10 may be formed of an electrical insulator such as ceramics or synthetic resin. According to these embodiments, the high frequency current applied to the wafer can be prevented from escaping to the ground along the gas pipe by the mounting flange 12, and the high frequency current flows to the motor 61 side. Can be prevented by the passage block 7 or the slack piston 10.

In FIG. 3, the cylinder 1 and the motor housing 5 are separated from each other, and a first injection / discharge passage 71a for opening the passage block 7 to the cylinder 1 and a first flange 72a having a first flange 72a. A block 7a, a second injection / discharge passage 71b and a discharge passage 73 communicating with the switching valve device 6.
And a second block 7b having a second flange 72b, and the first flange 72a of the first block 7a is fixed to the mounting flange 12 by a fixing means such as a tightening screw; , The second flange portion 72b of the second block 7b,
The motor housing 5 is fixed by a fixing means such as a tightening screw.
On the other hand, connectors 40 and 41 are screwed to the inlet of the first discharge passage 71a and the outlet of the second discharge passage 71b. Second
The injection passages 71a and 71b are connected by the connecting pipe 30 having an electric insulation structure made of a synthetic resin such as a fluorine resin. Further, between the flanges 72a and 72b, the facing chamber 2 is provided.
A communication tube 31 for communicating the surge volume 20 with the surge volume 20 is provided, and the orifice 21 is provided in the communication tube 31.

By doing so, it is possible to prevent the high frequency current applied to the wafer from escaping to the ground via the gas pipe by the connecting pipe 30.
The high-frequency current can be prevented from flowing toward the motor 61 by the communication pipe 30 and the communication pipe 31.

When the cylinder 1 of the cryopump having the slack piston 10 and the motor housing 5 are separated as shown in FIG. 3, the communication pipe 31 is required.
By eliminating the slack piston 10 as shown in FIG. 4, the communication pipe 31 can be made unnecessary.

In FIG. 4, at the end of the first block 7a on the side of the displacer 3, it extends in the reciprocating direction of the displacer 3 and communicates with the first discharge / discharge passage 71a. Lumen 74
A cylindrical portion 75 having a through hole at the upper end of the displacer 3 and having a through hole at the center thereof.
Is provided with a protruding portion 32 which reciprocates freely, and around the outer circumference of the cylindrical portion 75 and the protruding portion 32, the first block 7 is provided.
a pressure control chamber 33 whose volume changes with the reciprocation of the displacer 3 is provided between
The first block 7a is provided with a communication passage 76 for connecting the pressure control chamber 33 to the first injection / discharge passage 71a, and the communication passage 76 is provided with the orifice 34. Then, the inner space of the inner cavity 74 is defined by the pressure control chamber 3.
3 and is a relay chamber 35 communicating with the inside of the displacer 3. The high-pressure gas introduced into the first discharge passage 71 a is guided into the displacer 3 through the relay chamber 35. Further, the low-pressure gas in the cylinder 1 is discharged from the displacer 3 to the first injection / discharge passage 71a via the injection / discharge relay chamber 35. When the high-pressure gas is introduced into the cylinder 1 from the first injection / discharge passage 71a, a part of the high-pressure gas flowing through the first injection / discharge passage 71a is introduced from the orifice 34 into the pressure control chamber 33, and the pressure control is performed. The chamber 33 has an intermediate pressure,
Due to the pressure difference between the intermediate pressure in the pressure control chamber 33 and the high pressure in the cylinder 1, the displacer 3 is caused to move upward.
The gas in the pressure control chamber 33 is compressed, and the intermediate pressure gradually increases from an intermediate pressure between the high pressure and the low pressure to approach a high pressure.
The pressure difference with the high pressure inside becomes smaller. When the pressure in the cylinder 1 becomes low due to the switching valve device 6, the displacer 3 is caused to move back toward the heat stage 11 by the pressure difference between the intermediate pressure in the pressure control chamber 33 and the low pressure in the cylinder 1. In addition, at this time, the volume of the pressure control chamber 33 increases, and the intermediate pressure inside the pressure control chamber 33 gradually decreases, and the pressure difference between this intermediate pressure and the low pressure in the cylinder 1 decreases.

[0027]

As described above, according to the present invention, the electric insulator 24 is interposed between the mounting flange 12 for mounting the motor housing 5 to the cylinder 1 and the motor housing 5, and the switching of the switching valve device 6 is performed. A passage block 7 having an injection / discharge passage 71 for introducing high-pressure gas and discharging low-pressure gas is formed of an electric insulator, and the mounting flange 12 and the motor housing 5 are connected by means of an electric insulating structure. Therefore, when the wafer is directly cooled by the heat stage 11 and a high-frequency current is applied to the wafer to etch the wafer, the high-frequency current escapes to the ground along a gas pipe connected to the motor housing 5. Can be prevented by the coupling means of the electric insulator 24 and the electric insulating structure. Since the escape can be prevented by the passage block 7, it can effectively protect the coil coating of motor. Further, since the wafer can be directly cooled by the heat stage 11, not only the cooling effect of the wafer is high, but also it is not necessary to form the whole pump in a large size.

Further, the motor housing 5 and the valve body 62 of the switching valve device 6 are formed of an electric insulator, or the mounting flange 12 and the passage block 7 are formed of an electric insulator, or By forming the mounting flange 12 and the slack piston 10 with an electric insulator, the high-frequency current can be prevented from escaping to the ground through a gas pipe without providing a special electric insulator. Since the motor 61 can be protected from the above, the configuration is very simple and the cost can be reduced.

The cylinder 1 and the motor housing 5
And the passage block 7 is divided into a first block 7a and a second block 7b, and the first and second discharge passages 71a, 71b of these blocks 7a, 7b are separated.
Is connected by the communication pipe 30 having an electrically insulating structure, the motor housing 5 can be disposed at an unspecified position separated from the cylinder 1 while being insulated. Therefore, even when the space at the pump mounting position is small, The cylinder 1 can be disposed at a desired position.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing another embodiment.

FIG. 3 is a partially omitted sectional view showing another embodiment.

FIG. 4 is a partially omitted cross-sectional view showing another embodiment.

FIG. 5 is a sectional view of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 cylinder 11 heat stage 12 mounting flange 3 displacer 5 motor housing 6 switching valve device 61 motor 62 valve body 7 passage block 7a first block 7b second block 71 injection passage 71a first injection passage 71b second injection passage 73 Discharge passage 10 Slack piston 24 Electrical insulator 30 Connecting pipe

Claims (5)

(57) [Claims] 1. A cylinder 1 having a heat stage 11;
A motor housing 5 mounted to the cylinder 1 via a mounting flange 12, a switching valve device 6 having a motor 61 housed in the motor housing 5, and switching of the switching valve device 6 to introduce high-pressure gas and reduce pressure. A cryoblock having a passage block 7 having an injection / discharge passage 71 for discharging gas, and a displacer 3 housed in the cylinder 1 and reciprocating by introducing high-pressure gas into the cylinder 1 and discharging low-pressure gas. In the pump, an electric insulator 24 is interposed between the mounting flange 12 and the motor housing 5, and the passage block 7 is formed of an electric insulator.
A cryopump characterized in that the mounting flange (12) and the motor housing (5) are connected by a connecting means having an electrically insulating structure. 2. A cylinder 1 having a heat stage 11;
A motor housing 5 mounted to the cylinder 1 via a mounting flange 12, a switching valve device 6 having a motor 61 housed in the motor housing 5, and switching of the switching valve device 6 to introduce high-pressure gas and reduce pressure. A cryoblock having a passage block 7 having an injection / discharge passage 71 for discharging gas, and a displacer 3 housed in the cylinder 1 and reciprocating by introducing high-pressure gas into the cylinder 1 and discharging low-pressure gas. In the pump, the motor housing 5;
The valve element 6 of the switching valve device 6 in contact with the passage block 7
A cryopump characterized in that 2 and 3 are formed of an electrical insulator. 3. A cylinder 1 having a heat stage 11;
A motor housing 5 mounted to the cylinder 1 via a mounting flange 12, a switching valve device 6 having a motor 61 housed in the motor housing 5, and switching of the switching valve device 6 to introduce high-pressure gas and reduce pressure. A cryoblock having a passage block 7 having an injection / discharge passage 71 for discharging gas, and a displacer 3 housed in the cylinder 1 and reciprocating by introducing high-pressure gas into the cylinder 1 and discharging low-pressure gas. A cryopump, wherein the mounting flange 12 and the passage block 7 are formed of an electrical insulator. 4. A cylinder 1 having a heat stage 11;
A motor housing 5 mounted to the cylinder 1 via a mounting flange 12, a switching valve device 6 having a motor 61 housed in the motor housing 5, and switching of the switching valve device 6 to introduce high-pressure gas and reduce pressure. A passage block 7 having an injection / discharge passage 71 for discharging gas; a displacer 3 which is housed in the cylinder 1 and reciprocates by introducing high-pressure gas into the cylinder 1 and discharging low-pressure gas; A cryopump provided with a slack piston 10 interposed between the displacer 3 and
A cryopump wherein the mounting flange 12 and the slack piston 10 are formed of an electrical insulator. 5. A cylinder 1 having a heat stage 11;
A motor housing 5 mounted to the cylinder 1 via a mounting flange 12, a switching valve device 6 having a motor 61 housed in the motor housing 5, and switching of the switching valve device 6 to introduce high-pressure gas and reduce pressure. A cryoblock having a passage block 7 having an injection / discharge passage 71 for discharging gas, and a displacer 3 housed in the cylinder 1 and reciprocating by introducing high-pressure gas into the cylinder 1 and discharging low-pressure gas. In the pump, the cylinder 1 and the motor housing 5 are separated from each other, and the passage block 7 communicates with a first block 7 a having a first discharge passage 71 a opening to the cylinder 1 and the switching valve device 6. Divided into a second block 7b having a second injection passage 71b,
The first block 7a is fixed to the mounting flange 12 of the cylinder 1 and the second block 7b is fixed to the motor housing 5, while the first and second injection passages 71a, 71b are electrically insulated. A cryopump, wherein the cryopumps are connected by a communication pipe 30.