JP3052096B2 - 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 used in semiconductor manufacturing equipment and the like.

[0002]

2. Description of the Related Art A cryopump is a vacuum pump that condenses gas molecules on an extremely cooled surface and exhausts the gas molecules, and is used in a semiconductor manufacturing apparatus that requires a clean ultra-high vacuum. Generally, a cryopump includes a first condensing portion having a cryogenic surface of about 50-80 ° K, and a second condensing portion having a cryogenic surface of about 10-20 ° K, In the section, mainly water vapor is frozen, and in the second condensation section, hydrogen, oxygen, nitrogen,
Freezes or adsorbs argon, etc.
The gas molecules accumulated on the condensing surface are periodically discharged. As described above, since the gas molecules are condensed and exhausted, there is no backflow of oil or the like, and a clean ultra-high vacuum can be obtained.

[0003]

The conventional cryopump has only one intake port for sucking gas from the exhaust chamber. The inlet is provided as an opening with one end of the pump case open, and gas molecules entering from the inlet enter a cup-shaped first condensate, where water vapor passes through the first condensate. The inside surface is frozen and evacuated, and hydrogen, oxygen, argon and the like are frozen or adsorbed and evacuated on the surface of the second condensation portion provided inside the first condensation portion. Further, the water vapor that has entered the heat insulating gap between the first condensed portion and the inner surface of the case is frozen and exhausted on the outer surface of the first condensed portion.

[0004] Such a single inlet type pump structure is
Only a single evacuated chamber can be evacuated. Therefore, conventionally, when a plurality of evacuated chambers are each to be evacuated to a clean ultrahigh vacuum by a cryopump, one cryopump must be applied to each evacuated chamber.
A large number of pumps are used in the entire system, which is problematic in terms of cost, space and maintenance.

The present invention has been made in view of such a conventional problem, and has as its object to provide a cryopump capable of simultaneously evacuating a large number of evacuated chambers by one unit.

[0006]

In order to achieve the above object, a cryopump according to the present invention is provided with a first cryopump at one end of a case.
And a substantially cup-shaped first condensed portion is disposed inside the case toward the first air inlet, and a second condensed portion is disposed inside the first condensed portion. A second intake port is provided near the other end of the case, and a third condensation section is provided between the first condensation section and the second intake port.

Further, the third condensing portion is configured to perform the exhaust more effectively and to prevent the gas molecules sucked from the second inlet from flowing back into the exhaust chamber from the first inlet. A labyrinth is provided in the vicinity of the condensed part.

When hydrogen, oxygen, argon and the like enter from the second intake port, a vent hole is provided at the bottom of the first condensed portion so that those gas molecules can also be exhausted.

[0009]

The gas from the first exhausted chamber enters the first condensed portion from the first intake port, and the water vapor is frozen and exhausted at a very low temperature inside the first condensed portion, and hydrogen, oxygen, Argon or the like is frozen or adsorbed and exhausted on the cryogenic surface of the second condensation part.
The water vapor that has entered the gap between the first condensation part and the case is frozen and exhausted on the cryogenic surface outside the first condensation part.

On the other hand, the gas from the second chamber to be exhausted is sent from the second intake port to the third condensing portion, and the water vapor is frozen and exhausted on the cryogenic surface of the third condensing portion. By providing a labyrinth in the vicinity of the third condensed part, the effective contact area of gas with the third condensed part can be increased, and the exhaust capability of the third condensed part can be increased. The inhaled gas molecules are less likely to flow back into the exhaust chamber from the first inlet.

Further, by providing a vent hole at the bottom of the first condensing portion, hydrogen, oxygen, argon, etc. from the second air inlet are guided to the inside of the first condensing portion, and the second condensing portion is provided. It becomes possible to exhaust. However, such a vent hole does not need to be provided for a chamber to be evacuated, such as a load lock chamber, which only needs to mainly evacuate water vapor.

[0012]

FIG. 1 shows the structure of a cryopump according to an embodiment of the present invention. The cryopump case 10 is made of stainless steel and has a cylindrical side surface. The upper end is open to form an opening 12, and the lower end is closed by a bottom plate 14. The opening 12 forms a first intake port, and is connected to a first exhaust chamber (not shown) via a gate valve (not shown) or the like. Around the first intake port 12,
A flange 16 for attaching and fixing the cryopump to the first exhaust chamber is formed integrally with the case 10.

Inside the case 10, a case bottom plate 1
4, a refrigeration cylinder 18 is erected at the center of the refrigeration cylinder 18, and first and second condensed portions 20, 22 made of a material having high thermal conductivity, for example, aluminum.
Is arranged.

The first condensing portion 20 has a substantially cup-shaped configuration, and is attached to the refrigeration cylinder 18 toward the first air inlet 12, that is, with the cup opening facing the first air inlet 12. You. Between the first condensation part 20 and the case 10,
A gap 24 for heat insulation is provided. The second condensing part 22
A cylindrical body having a smaller diameter than the first condensing portion 20, which is attached to the refrigeration cylinder 18 inside the first condensing portion 20. Activated carbon for effectively adsorbing gas molecules such as hydrogen, oxygen, and argon is adhered to the surface of the second condensed portion 22. A plurality of annular cap-shaped baffles 15 for preventing backflow of gas are arranged concentrically at the first intake port 12.

The lower end of the freezing cylinder 18 is
Is connected to the refrigerator 26 through the opening. The refrigerator 26 receives high-pressure helium from a compressor (not shown) from a high-pressure port 28, condenses the input high-pressure helium with a condenser, and then evaporates (adiabatic expansion) with an evaporator to generate cryogenic cold air. I do. Helium converted into low-pressure gas by the evaporator is sent out from the low-pressure port 30 to the compressor.

The cryogenic cold air generated in the refrigerator 26 passes through the refrigeration cylinder 18 to the first and second condensing sections 20 and 20.
22. Thereby, the surface of the first condensation part 20 is cooled to, for example, 40 ° K, and the second condensation part 22 is cooled.
Is cooled to, for example, 15 ° K.

In order to discharge the gas molecules stored in the condensing portions 20 and 22, a neutral gas, for example, nitrogen gas N2 is supplied from the purge port 32 to the case while the cryopump is shut off from each of the discharge chambers. 10 to vent the room. This vent causes gas molecules to evaporate from the surfaces of the condensed portions 20 and 22, and is exhausted from the out port 34 together with the neutral gas.

In this embodiment, two opposed intake ports 36 and 38 are provided on the side surface of the lower end of the case 10. These intake ports 36 and 38 are second intake ports, and are respectively connected to second and third exhaust chambers (not shown) via pipes.

In the case 10, a third condensed portion 40 is provided integrally with the first condensed portion 20 and extends vertically from the bottom plate 20a toward the lower end of the case. In the present embodiment, the third condensed portion 40 is
An outer cylindrical condensed portion 42 having the same diameter as the condensed portion 20 of the above, and an inner cylindrical condensed portion 44 having a smaller diameter than the outer cylindrical condensed portion 40. These outer and inner cylindrical consolidations 42, 44
At the same temperature as the surface of the first condensed portion 20 (4
0 ° K).

An annular horizontal support plate 46 is attached and fixed to the inner surface of the case 10 below the third condensed portion 40. The horizontal support plate 46 has an outer cylindrical condensed portion 42 and an inner cylindrical condensed portion. An outer cylindrical labyrinth plate 48 interposed between the inner cylindrical labyrinth plate 44 and the inner cylindrical labyrinth plate 50 interposed between the inner cylindrical condensed portion 44 and the freezing cylinder 18 are erected.
Further, a large number of ventilation holes 52 are formed in the outer peripheral portion of the bottom plate 20a of the first condensed portion 20 in the circumferential direction.

In the cryopump having such a configuration, gas from the first exhausted chamber flows into the first condensing portion 20 through the gap between the first air inlet 12 and the baffle 15. Here, the steam is frozen and exhausted on the inner surface (40 ° K) of the baffle 15 and the first condensed portion 20, and the hydrogen
Oxygen, argon and the like are frozen or adsorbed and exhausted on the surface (15 ° K) of the second condensation part 22. Further, the water vapor that has entered the gap 24 between the first condensed portion 20 and the case 10 is
The first condensed portion 20 is frozen and evacuated on the outer surface (40 ° K).

On the other hand, the case 1
The gas molecules flowing from the second and third exhausted chambers into the inside of the second condensing portion 40 are outside and inside the third condensing portion 40 and the inside cylindrical condensing portion 4.
2,44 and outer and inner cylindrical labyrinth plates 48,50
The steam enters the labyrinth 54 which is defined by the following formulas. In the labyrinth 54, the water vapor is supplied to the inside and outside surfaces (40 ° K) of the inner cylindrical condensing portion 44 and the inner side surface (40
It is frozen and evacuated at ゜ K). In addition, hydrogen, oxygen, argon, and the like enter the inside of the first condensed portion 20 from the labyrinth 54 through the vent hole 52, and enter the surface (15) of the second condensed portion 22.
凍結 K) freezes or adsorbs and exhausts. The water vapor that cannot be completely exhausted by the labyrinth 54 enters the inside of the first condensed portion 20 through the hole 52 or enters the gap 24 through the labyrinth 54, and is formed on the inner surface or the outer surface of the first condensed portion 20. Freeze and exhaust.

As described above, in the cryopump of the present embodiment, the gas from the first chamber to be evacuated is introduced into the inside of the first condensing section 20 having a substantially cup-like shape, and the steam is supplied to the first condensing section 20. While condensing and exhausting hydrogen, oxygen, argon and the like in the second condensing section 22, and gas from the second and third exhaust chambers to the third condensing section 20 on the back side of the first condensing section 20. The steam is introduced into the labyrinth 54 formed by the condensing part 40 and the labyrinth plates 48 and 50, and the water vapor is supplied to the third condensing part 4.
In addition to condensing and exhausting at 0, hydrogen, oxygen, argon and the like are further guided inside the first condensing portion 20 through holes 52 provided in the bottom plate of the first condensing portion 20 and condensed by the second condensing portion 22. I made it exhaust. As a result, the first and second
And the third chamber to be evacuated simultaneously, for example, 1 × 10 ⁻⁹ T
It can be evacuated (evacuated) to a clean ultra-vacuum state of about oor.

In particular, in the cryopump of this embodiment, the third condensing portion 40 has a large effective area in contact with gas molecules by the action of the labyrinth 54, and can effectively exhaust water vapor even with a relatively small size. . Also,
Since hydrogen, oxygen, argon, and the like from the second and third exhaust chambers are led to the second condensation section 22 through the holes 52 provided in the bottom plate of the first condensation section 20, all the exhaust chambers are exhausted. The second condensing part 22 is shared with the exhaust.

FIG. 2 shows the structure of a cryopump according to a modification. This modified example is different from the above-described embodiment in that the intake ports 60 and 62 are attached to the bottom plate 14 of the case 10 as the second intake port, and the third condensed portion is the same as the first condensed portion 20. A labyrinth 68 is constituted by one cylindrical labyrinth plate 66 having one cylindrical condensing portion 64 having a diameter, and hydrogen, oxygen, and hydrogen from the intake ports 60 and 62 are formed.
There is no means for guiding argon or the like to the second condensing portion 22 side.

As described above, the second intake port can be provided at an arbitrary position near the end of the case opposite to the first intake port 12. Further, the number of the second intake ports is not limited to two, but may be one, or may be three or more. The labyrinth means may be any as long as it increases the contact area of the gas molecules with the third condensed portion, and an arbitrary structure can be selected.

Further, as in a load lock chamber in a semiconductor manufacturing apparatus, a cryopump may be used mainly for exhausting water vapor. In such a case, only the third condensate is sufficient. Therefore, as in this modification, the hydrogen, oxygen, argon, etc.
It is also possible to omit the ventilation hole for guiding to the condensed part side. Further, the structure of the second condensed portion is not limited to the cylindrical shape as in the above-described embodiments and modified examples. For example, a large number of cap-shaped plate members may be arranged at regular intervals.

Next, an example in which the cryopump according to the present invention is applied to an ion implantation apparatus of a semiconductor manufacturing system will be described with reference to FIG. In this ion implantation apparatus, 100
Is a process chamber for performing ion implantation, 102 and 104
Is a load lock chamber, 106 is a cryopump according to the present invention, 108 to 116 are gate valves, 118 is a rotary pump, 122 to 128 are solenoid valves, and 130 to 136 are pipes.

The semiconductor wafer 150 is transferred to the gate valve 10 by a wafer transfer mechanism (not shown) such as a turntable.
8 is carried into the load lock chamber 102 through the gate valve 11 by the hand arm in the load lock chamber 102.
0 is set in the process chamber 100.
Similarly, the semiconductor wafer 150 is set in the process chamber 100 also from the load lock chamber 104 side. After the ion implantation process is completed, the semiconductor wafer 150 is carried out of the process chamber 100 via the load lock chambers 102 and 104 by the operation opposite to the above.

The process chamber 100 serves as a first evacuated chamber through a gate valve 116 and a cryopump 1.
06 is connected to the first intake port (12). As a result, the process chamber 100 is
^Is constantly evacuated to a clean ultra-high vacuum suitable for the ion implantation process, for example, about 1 × 10 ⁻⁷ .

The load lock chambers 102 and 104 are connected to the pipe 1
30 and 132, and is connected to a rotary pump 118, and a pipe 134,
The cryopump 106 is connected to the second intake port (36, 38) via 136. Each load lock room 10
Each time the semiconductor wafers 150 are loaded one by one, the chamber 2104 must be evacuated (evacuated) from atmospheric pressure to a vacuum of about several tens mm Torr.

In order to perform this evacuation, first, the electromagnetic valve 12
When the load lock chambers 2 and 128 are turned on, the load lock chambers 102 and 104 are roughly evacuated to about several 100 mmTorr by the rotary pump 118. Normally, when the degree of vacuum exceeds about 100 mmTorr, oil flows backward from the rotary pump to the chamber to be evacuated.
22 and 128 are turned off.

Next, the solenoid valves 124 and 126 are turned on, and the two load lock chambers 1 are driven by the cryopump 106.
Evacuate 02,104. Since almost only water vapor remains in each of the load lock chambers 102 and 104 due to roughing by the rotary pump 118, a pump structure without a vent hole (52) as in the modification of FIG.
Can be used. When the pressure in each of the load lock chambers 102 and 104 reaches about several tens mmTorr by the evacuation by the cryopump 106, the solenoid valves 124 and 126
Turn off.

The cryopump 106 continues to evacuate the process chamber 100 while the load lock chambers 102 and 104 are evacuated. That is, the cryopump 106 simultaneously evacuates the process chamber 100 and the two load-lock chambers 102 and 104 to a total of three evacuated chambers.

In this ion implantation apparatus, the volume of the process chamber 100 is, for example, about 100 liters, while the volume of each of the load lock chambers 102, 104 is, for example, about 0.3 liters. Even if the exhaust of the load lock chambers 102 and 104 is added to the load lock chamber 106, the exhaust capacity of the cryopump 106 is hardly affected.

The load lock chamber may include a sputtering device, a vapor deposition device, a CVD,
The cryopump of the present invention can be applied to various semiconductor manufacturing apparatuses such as PVD and epitaxial apparatuses. Further, the present invention can be applied to various devices including an exhaust chamber other than the load lock chamber.

[0037]

As described above, according to the cryopump of the present invention, the gas from the first chamber to be exhausted is introduced into the first condensing portion from the first intake port, and the first condensed portion is formed. At the cryogenic surface of the second condensing portion, for example, water vapor is frozen and exhausted, and at the cryogenic surface of the second condensing portion, for example, hydrogen, oxygen, argon, etc. are condensed and exhausted, and at the same time, gas from the second exhaust chamber is discharged to the second Is introduced to the third condensed portion from the intake port of the device, and for example, the steam is frozen and evacuated on the cryogenic surface, so that a plurality of evacuated chambers can be simultaneously evacuated to a clean high vacuum state by one unit. it can.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view showing a structure of a cryopump according to a modification.

FIG. 3 is a block diagram showing an example in which a cryopump according to the present invention is applied to an ion implantation apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Case 12 1st inlet 15 Baffle 20 1st condensing part 22 2nd condensing part 36 Intake port (2nd inlet) 38 Intake port (2nd inlet) 40 3rd condensate 54 Labyrinth Reference Signs List 60 suction port (second suction port) 62 suction port (second suction port) 40 third condensing part 68 labyrinth 100 process chamber 102 load lock chamber 104 load lock chamber 106 cryopump

Claims (1)

(57) [Claims] 1. A first intake port is provided at one end of a case,
A substantially cup-shaped first condensing portion is disposed inside the case toward the first air inlet, and a second condensing portion is disposed inside the first condensing portion. A cryopump comprising a second suction port provided near the other end, and a third condensation section provided between the first condensation section and the second suction port.