JPH10252650A - Cryopump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cryopump to be also applicable for a large cryopump and have crank structure durable against strength. SOLUTION: A cryopump comprises a cold cylinder arranged in a vacuum chamber; a displacer 19 slid in the cold cylinder; a crank mechanism 21 coupled to the displacer through a connecting rod; a motor 25 to drive the crank mechanism; a feed valve element 110 coupled to the crank mechanism and feed a refrigerant in the cold cylinder by opening and closing a feed port; and a discharge valve element 116 coupled to the crank mechanism and discharging a refrigerant from the cold cylinder by opening and closing a discharge port. The displacer 19 is coupled to the central part of the crank mechanism 21 through a connecting rod 23 and the feed valve element 110 and the discharge valve element 116 are coupled to the both sides thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cryopump used for generating a high vacuum in, for example, a semiconductor manufacturing process.

[0002]

2. Description of the Related Art Generally, a cold cylinder provided in a vacuum chamber, a displacer sliding in the cold cylinder, a crank mechanism connected to the displacer via a connecting rod, and a motor for driving the crank mechanism And a supply valve element connected to the crank mechanism and supplying a refrigerant into the cold cylinder by opening and closing a supply port, and a refrigerant connected to the crank mechanism and opening and closing a discharge port to discharge the refrigerant from the cold cylinder. 2. Description of the Related Art A cryopump provided with a discharge valve for discharging is known. Conventionally, in this type, a crank mechanism is supported in a cantilever manner, and the displacer is connected to a distal end side thereof via a connecting rod, and a supply valve body and a discharge valve body are connected to a proximal end side thereof. And a compact configuration has been proposed.

[0003]

However, in recent years, a cryopump larger than a conventional one has been realized, and accordingly, a displacer is connected to a distal end side of a crank mechanism through a connecting rod as in the conventional case. Have a problem that it becomes difficult to support the force applied to the crank mechanism.

Accordingly, an object of the present invention is to provide a cryopump having a strong crank structure which is applicable to a large cryopump.

[0005]

In order to solve the above-mentioned problems, a first aspect of the present invention provides a cold cylinder provided in a vacuum chamber, a displacer sliding in the cold cylinder, and a connecting rod attached to the displacer. A crank mechanism connected to the crank mechanism, an electric motor driving the crank mechanism, a supply valve element connected to the crank mechanism to supply a refrigerant into the cold cylinder by opening and closing a supply port, and the crank mechanism In a cryopump having a discharge valve body that discharges refrigerant from the cold cylinder by opening and closing a discharge port, the displacer is connected to a central portion of the crank mechanism via the connecting rod, The supply valve body and the discharge valve body are Is is characterized in that the linked.

According to the present invention, since the force received from the displacer is supported at the center of the crank mechanism, it is stronger in strength than the conventional one supported at the tip, so that a large cryo It can be applied to pumps.

According to a second aspect of the present invention, in the first aspect, a liner for slidably housing the supply valve body and the discharge valve body is provided, and the liner is housed in a liner housing portion of a housing. An opening for guiding the refrigerant flowing into the liner from the cold cylinder into the liner is formed in the liner that accommodates the discharge valve body and the liner accommodating portion. It is characterized by being discharged through the interior.

According to this, since the refrigerant is discharged to the outside through the housing and the inside of the motor, the structure of the flow path for discharge is simplified and compact, and the cooling of the windings and the like inside the motor is promoted. Is done.

According to a third aspect of the present invention, in the first or second aspect, the crank mechanism is supported in a double-ended manner.

[0010] According to this, the strength is further improved as compared with the conventional one, so that it can be applied to a large cryopump.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, a cryopump 1 according to the present embodiment comprises a cryogenic refrigerator 3 using a Gifford-McMahon cycle, a cylindrical vacuum chamber 5, and the like. Line vacuum processing tank 7
Is provided on the lower surface of the main body. In the figure, reference numeral 9 denotes a gate valve, which shuts off communication between the vacuum processing tank 7 and the cryopump 1 by means of a sliding valve element 11. The refrigerator 3 includes a body 15 fastened to the lower surface of the vacuum chamber 5, a cold cylinder 17 disposed in the vacuum chamber 5, and a cold cylinder 1.
2 and a displacer 19 sliding in the axial direction in FIG.
And a motor 25 for driving the displacer 19 via a crank mechanism 21 and a connecting rod 23, which will be described in detail later with reference to FIG.

The body 15 of the refrigerator 3 has a refrigerant introduction pipe 27
And a refrigerant discharge pipe 29 connected to a compressor unit (not shown), and helium gas as a refrigerant circulates between the refrigerator 3 and the compressor unit. Further, the body 15 is connected to a roughing pump (not shown) via a roughing pipe 31, and the roughing pump roughly vacuums the vacuum chamber 5.

The cold cylinder 17 has a first cold head 33 having a relatively large mass at a substantially middle position in the vertical direction.
Is formed, and a second cold head 35 having a relatively small mass is formed at the upper end. At the upper end of the first cold head 33, a radiation shield 37 opening upward is provided.
Is attached.

The radiation shield 37 is formed in a cylindrical shape slightly smaller in diameter than the vacuum chamber 5 and holds a plurality of baffle rings 39 inside an opening extending to near the upper end of the vacuum chamber 5. .

At the upper end of the second cold head 35, a cold panel holder 41 opened downward is attached. The cold panel holder 41 is formed in a cylindrical shape having a relatively small diameter, and holds a plurality of cold panels 43 on an upper end surface and an outer peripheral surface thereof. Activated carbon 45 is adhered to the upper surface of the cold panel 43 except for the one located at the uppermost position.

On the other hand, the vacuum chamber 5 has a body portion 51 for accommodating the cold cylinder 17 and the radiation shield 37 and the like, a flange 53 fastened to the gate valve 9,
And a bottom plate 55 fastened to the body 15 of the refrigerator 3. A regeneration gas introduction pipe 57 connected to a regeneration gas supply source (not shown) is connected to and opened in the body 51, and a regeneration gas discharge pipe 59 connected to an exhaust treatment device (not shown) penetrates. The regeneration gas introduction pipe 57 is connected to the vacuum chamber 5
After being bent upward in the inside, it opens into the radiation shield 37.

In this embodiment, as shown in FIG. 2, the body 15 includes a mounting plate 101, a housing 102, a first bearing box 103, and a second bearing box 104. A shaft 25a of the electric motor 25 extends into the housing 102, and the shaft 25a is supported by a first bearing box 103 and a second bearing box 104 in a double-supporting manner via a pair of bearings 105 and 106. .

The shaft 25a has a crank mechanism 2 attached thereto.
1 is provided. The crank mechanism 21 includes a first eccentric portion 21a, a second eccentric portion 21b, and a third eccentric portion 21c.
Is connected to one end 23a of the connecting rod 23, and a displacer 19 is connected to the other end 23b of the connecting rod 23. First eccentric part 2
1a and the third eccentric portion 21c are located on both sides of the second eccentric portion 21b.

A bearing 108 is fitted into the first eccentric portion 21a on the side of the electric motor 25, and a supply valve body 110 is in contact with an outer peripheral portion of the bearing 108 in a vertically movable manner. The supply valve body 110 is accommodated in a supply-side liner 111 formed integrally with the mounting plate 101, and the supply-side liner 111 is connected to the liner accommodation portion 11 of the housing 102.
4 The supply-side liner 111 and the liner accommodating portion 114 are provided with a supply port 112 communicating with the refrigerant introduction pipe 27, and the supply port 112 is normally shielded by the supply valve body 110. When the supply valve element 110 is lowered by the rotation of the first eccentric portion 21a, and the supply valve element 110 is lower than the upper edge of the supply port 112, the supply port 112 is opened, and the helium gas from the refrigerant introduction pipe 27 is supplied to the liner. 111 and the liner 111
Is supplied to the cold cylinder 17 through the upper opening 113 of the cylinder.

A bearing 115 is fitted in the third eccentric portion 21c, and the outer peripheral portion of the bearing 115 is
6 abuts up and down freely. This discharge valve body 116
Are housed in a discharge-side liner 117 formed integrally with the mounting plate 101, and the discharge-side liner 117 is
Is housed in the liner housing 120 of the housing 102. A notch 118 is provided in the liner accommodating portion 120 for accommodating the liner 117 on the discharge side.
Communicates with a discharge port 119 provided in the liner 117, which is normally shielded by a discharge valve element 116. Then, the discharge valve body 116 descends due to the rotation of the third eccentric portion 21c, and when the discharge valve body 116 falls below the upper edge of the discharge port 119, the discharge port 11
9, the helium gas in the cold cylinder 17 flows into the liner 117 from the upper opening 121 of the liner 117, and flows into the housing 102 through the discharge port 119 and the notch 118 of the liner 117.
From here, it flows into the motor 25 through a passage (not shown), cools the windings and the like of the motor 25, and is discharged through the refrigerant discharge pipe 29.

Hereinafter, the operation of the present embodiment will be described.

In the sputtering process of the semiconductor wafer, the inside of the vacuum processing tank 7 is set to a high vacuum state in order to prevent unnecessary gas molecules from adhering to the surface of the semiconductor wafer. First, a vacuum of about 10 ^-2 Torr is obtained by roughly vacuuming the vacuum chamber 5 with a roughing pump. At this point, the communication between the vacuum chamber 5 and the vacuum processing tank 7 is shut off by the gate valve 9.

Next, the refrigerator 3 of the cryopump 1 is driven, and the high-pressure helium gas supplied from the compressor is repeatedly adiabatically expanded in the cold cylinder 17. Then, the cold storage material in the displacer 19 is gradually cooled,
The temperature of the cold cylinder 17 decreases. And the first
When the temperature of the cold head 33 becomes about 80K and the temperature of the second cold head 35 becomes about 15K, the gate valve 9 is opened to connect the vacuum chamber 5 and the vacuum processing tank 7. At this time, the vacuum processing tank 7 is roughly evacuated to a crossover pressure or lower by a roughing pump (not shown).

When the vacuum chamber 5 and the vacuum processing tank 7 are communicated with each other, gas molecules in the vacuum processing tank 7 are condensed or adsorbed in the radiation shield 37, and a high vacuum is obtained. That is, gas molecules having a high condensation temperature, such as water, condense and solidify in the form of frost on the surfaces of the baffle ring 39 and the radiation shield 37, and gas molecules such as argon, oxygen, and nitrogen condense in the form of frost on the surface of the cold panel 43.・ It solidifies.
Gas molecules such as helium, hydrogen, and neon are adsorbed on the activated carbon 45 attached to the cold panel 43. Thereby, a high vacuum of about 10 ⁻³ Torr is obtained in the vacuum processing tank 7.

On the other hand, when the evacuation by the cryopump 1 is performed continuously, the baffle ring 39 and the cold panel 43
And the like are covered by the condensed gas molecules, the exhaust efficiency is reduced, and a high vacuum cannot be obtained. Therefore, when the temperature of the second cold head 35 does not drop below a predetermined value or a predetermined degree of vacuum cannot be obtained, the cryopump 1 is regenerated. In this regeneration, after the communication between the vacuum chamber 5 and the vacuum processing tank 7 is cut off by the gate valve 9, the sheath heater (not shown) is energized to heat the first and second cold heads 33 and 35. Then, the baffle ring 39 and the cold panel 43
Since the gas molecules condensed into the gas are vaporized, the gas molecules are discharged from the regeneration gas discharge pipe 59 together with the regeneration gas introduced from the regeneration gas introduction pipe 57.

In this embodiment, it is assumed that the refrigerator 3 is made large. When the refrigerator 3 becomes large, when the high-pressure helium gas supplied from the compressor is repeatedly adiabatically expanded in the cold cylinder 17, an excessive force acts on the above-described crank mechanism 21 more than before.

In this embodiment, since the crank mechanism 21 is supported in a two-sided manner, it can withstand a sufficient strength, and the connecting rod 23 is connected to the crank mechanism 2.
1 is connected to the central portion, so that the strength is balanced and the strength is further improved. Further, since the supply valve body 110 and the discharge valve body 116 are connected to both sides thereof, the refrigerator 3 can be manufactured compactly. . Also, the mounting plate 10
1 and the connecting rod 23 (see FIG. 2).
Are substantially coincident with each other, so that the vibration of the mounting plate 101 is suppressed to be lower than that in a conventional case (not shown) in which the center line of the mounting plate and the axis of the connecting rod are displaced. be able to. Further, a passage (not shown) connecting the supply port 112 and the discharge port 119 to the inside of the cold cylinder 17 is formed almost vertically (conventionally oblique), so that the length of the passage is shortened and the pressure drop is suppressed to a low level. Can be.

The description of the specific embodiment has been completed.
The present invention is not limited to the embodiments described above.
For example, in the above-described embodiment, the crank mechanism 21 is supported in a double-supported manner. However, the present invention is not limited to this. It is also possible to connect the valve body and the discharge valve body.

[0030]

As described above, according to the cryopump of the present invention, the connecting rod is connected to the center of the crank mechanism, and the supply valve element and the discharge valve element are connected to both sides of the connecting rod. The strength of the refrigerator is improved, and the effect of suppressing the vibration and the pressure drop in the cryopump to a low level can be achieved.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing a crank mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cryopump 3 Refrigerator 5 Vacuum chamber 7 Vacuum processing tank 15 Body 17 Cold cylinder 19 Displacer 21 Crank mechanism 21a First eccentric part 21b Second eccentric part 21c Third eccentric part 23 Connecting rod 25 Electric motor 102 Housing 110 Supply Valve body 111, 117 Liner 112 Supply port 114, 120 Liner housing part 116 Discharge valve body 119 Discharge port

Claims (3)

[Claims] 1. A cold cylinder provided in a vacuum chamber, a displacer sliding in the cold cylinder, a crank mechanism connected to the displacer via a connecting rod, and an electric motor driving the crank mechanism. A supply valve connected to the crank mechanism and supplying a refrigerant into the cold cylinder by opening and closing a supply port, and a refrigerant is connected to the crank mechanism and discharges the refrigerant from the cold cylinder by opening and closing a discharge port. A cryopump having a discharge valve body, wherein the displacer is connected to the center of the crank mechanism via the connecting rod, and the supply valve body and the discharge valve body are connected to both sides thereof. And a cryopump. 2. A liner for slidably housing the supply valve body and the discharge valve body, the liner being housed in a liner housing part of a housing, and a liner for housing the discharge valve body and the liner housing part. 2. An opening for guiding a refrigerant flowing into the liner from the cold cylinder into the liner into the housing, and discharging the refrigerant guided into the housing through the opening through the interior of the electric motor. The cryopump described in 1. 3. The cryopump according to claim 1, wherein the crank mechanism is supported in a double-ended manner.