JP3309229B2 - Cryopump device with turbo molecular pump - 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 device used for a vacuum device such as a sputtering device and an ion plating device.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional exhaust system in which a condensable gas such as argon or nitrogen and a non-condensable gas such as hydrogen or helium are used in a vacuum apparatus. Further, there is known an exhaust device in which a cryopump c is connected to a vacuum device a via a vacuum valve b, and a turbo-molecular pump e is connected in parallel with the cryopump c via a vacuum valve d. In this exhaust device, the exhaust system of the cryopump c and the exhaust system of the turbo-molecular pump e are completely independent of each other. The condensable gas is exhausted by the cryopump c, and the non-condensable gas is exhausted by the turbo-molecular pump e. The pumps exhaust each other, compensating for their lack of performance. That is, the turbo molecular pump e has a low pumping speed for condensable gas (particularly water), whereas the cryopump c has a high pumping speed for condensable gas. In addition, the cryopump c cannot exhaust a large amount of non-condensable gas, but the turbo molecular pump e can continuously exhaust the gas. Can complement each other. An adsorbent that adsorbs non-condensable gas is installed inside the cryopump, and the non-condensable gas is exhausted with this. However, when a turbo molecular pump is provided, the adsorbent is a cryopump. c, the cryopump cannot exhaust any non-condensable gas. The condensable gas introduced into the vacuum device a is exhausted by the cryopump c, and the non-condensable gas is exhausted by the turbo molecular pump e. However, when the vacuum device a is a sputtering device or an ion plating device, Since the pumping speed of the cryopump c with respect to the argon gas is too high, the valve b is narrowed and the pumping speed is reduced. However, when argon gas is not used in the vacuum device a,
The valve b is fully opened to achieve a high vacuum quickly.

Further, as shown in FIG. 2, an exhaust device in which a cryopump c and a turbo molecular pump e are vertically connected in series to a vacuum device a is also used. Details of this are as shown in FIG. 3, in which the condensable gas is captured by the cryopump c at the preceding stage, and the non-condensable gas passing through the cryopump c is exhausted by the turbo molecular pump e. In this case, upper and lower cylindrical shield panels 1 are provided in the pump case f of the cryopump c, and horizontal bar-shaped 80K baffles h, h are provided above and below the shield panels 1 and are horizontally disposed therebetween. Is provided with a multiple umbrella-shaped 15K cryopanel g, a gas inlet i above the pump case f, and an opening j connecting the high vacuum port of the turbo molecular pump e below the pump case f. The cryopanel g and the baffle h To the refrigerator k attached to the pump case f and
And cool to 80K.

[0004]

Used INVENTION Problems to be Solved] vacuum device a in an argon gas such as a sputtering apparatus is large, usually argon pressure of 10 ^{- 3-10 -} at about ² Torr, the pressure is very for the turbo molecular pump e Therefore, in the case of FIG. 1, a wideband turbo-molecular pump capable of using a high pressure is used. This broadband turbomolecular pump has the disadvantage that the internal structure is complicated and expensive.

The examples shown in FIGS. 2 and 3 are of a type devised to overcome the drawbacks of FIG. 1, in which a cryopump c is arranged in series directly above a turbo molecular pump e. The condensable argon is exhausted by the cryopump c and hardly flows into the turbo molecular pump e. Therefore, the pressure at the high vacuum port of the turbo-molecular pump e can be reduced, and an expensive broad-band type is not required, and a low-cost standard turbo-molecular pump can be used. However, in this example, due to the structure, the 15 K
Due to the presence of the cryopanel g, there is a danger that the argon or moisture (ice) condensed on the cryopanel g will fall directly into the turbo molecular pump e. The rotor of the turbo molecular pump e normally rotates at high speed during operation,
If a small foreign object falls on it, it often leads to a catastrophic failure such as destruction of the rotor blades.Therefore, this type of exhaust device is not used for vacuum equipment that exhausts a large amount of condensable gas such as sputtering or ion plating. Not applicable. Also, in this type of apparatus, the regeneration of the cryopump must be performed with the turbo molecular pump disconnected.
In the example shown in FIG. 1, there is no danger of the turbo molecular pump e being destroyed by the fall of argon, but there is a drawback that the heat load is increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cryopump apparatus which can exhaust a large amount of condensable gas without failure due to falling of condensate using a standard type turbo molecular pump.

[0007]

According to the present invention, an inside of a pump case of a cryopump provided with a gas inlet above has an opening to the inlet and is connected to a refrigerator on a side of the pump case. Provided a cup-shaped shield panel, a cryopanel connected to the refrigerator inside the shield panel, and a high vacuum port of a turbo-molecular pump connected to a gas outlet formed below the pump case. In the cryopanel, a vertical hollow portion is formed in the cryopanel, and a gas flow opening smaller than the surface area is formed in a projection surface area of the cryopanel at a bottom portion of the shield panel. A first edge extending upward around the periphery, a gas outlet of the pump case formed below the gas flow opening of the shield panel, and a second edge extending upward around the gas outlet. Set The Rukoto, was to achieve the above object.

[0008]

The refrigerator of the cryopump is operated to cool the shield panel to about 80K and the cryopanel to about 15K. The vacuum valve is opened and the gas inlet is adjusted to an appropriate vacuum pressure. Connecting. And
When the turbo molecular pump is operated, the gas in the vacuum device flows to the turbo molecular pump via the cryopump, the condensable gas is condensed and discharged to the shield panel and the cryopanel, and the non-condensable gas is turbocharged. It is evacuated by a molecular pump. Although such an operation is the same as the example shown in FIG. 2, in the apparatus of the present invention, the hollow cryopanel forms a gas flow opening having an area smaller than the area of the projection surface area dropped on the shield panel, and the gas flow opening is formed around the gas flow opening. Since the first edge portion extending is provided, even if a gas having a low condensing temperature such as argon gas condensed on the outer surface of the cryopanel falls, it does not fall into the gas flow port, and therefore, the turbo connected to the gas flow port is provided. The molecular pump will not fail due to falling condensate. In addition, since the second edge portion extending upward is also provided around the gas flow port, even if condensate turns into liquefied gas during regeneration of the cryopump, it flows into the gas outlet of the pump case. In other words, it is possible to regenerate the turbo molecular pump without freezing it and causing it to fail.

[0009]

Embodiment An embodiment of the present invention will be described with reference to FIG.
Reference numeral 1 denotes a cylindrical pump case of a cryopump provided with a gas inlet 2 above, and the gas inlet 2 uses a large amount of condensable gas such as argon gas such as a sputtering device or an ion plating device. It is connected to a vacuum device via a vacuum valve (not shown). A refrigerator 3 is attached to the side of the pump case 1 and the pump case 1
The gas outlet 4 formed this downward 10 ^{- 3} Torr
A high-vacuum port 6 of a turbo-molecular pump 5 that operates to evacuate under a high vacuum is connected via a vacuum valve 10. Reference numeral 7 denotes a cup-shaped shield panel having an opening 8 to the gas inlet 2, 9 denotes a cryopanel provided inside the shield panel 7, and the shield panel 7 is a first-stage cold head of the refrigerator 3. The cryopanel 9 is connected to the cold head 3b of the refrigerator 3 and cooled to about 15K. Reference numeral 11 denotes a baffle provided in the opening 8 of the shield panel 7.

The cryopanel 9 is formed in an inverted cup shape having a vertically hollow portion 9a therein, and a gas flow smaller than the projected area is provided on the projection surface of the cryopanel 9 at the bottom 7a of the shield panel 7. An opening 12 was formed, a first edge 13 extending upward around the gas flow opening 12 was provided, and an annular first liquid receiving portion 14 was formed at the bottom of the shield panel 7. A gas outlet 4 of the pump case 1 is formed below the gas flow port 12 of the shield panel 7, and a second edge 15 extending upward around the gas outlet 4 is provided. An annular second liquid receiving portion 16 is also provided at the bottom of the pump case 1.
Was formed. The first and second liquid receiving portions 14 and 16 are provided with holes 17 and 18 for discharging liquefied gas, respectively.
The liquefied gas vent hole 18 of the liquid receiving part 16 is opened and closed by a valve 19. The diameter of the gas outlet 4 of the pump case 1 is formed smaller than the diameter of the gas flow port 12 of the shield panel 7, and a small gap is provided around the lower part of the second edge 15 around the gas flow port 12. The liquefied gas flows from the gas flow port 12 through the turbo molecular pump 5.
To prevent inflow to

[0011] The apparatus of this embodiment, 10 in advance roughing pump vacuum device ^- connected After evacuated to about ³ Torr,
Prior to the connection, the shield panel 7 is cooled to about 80K by the refrigerator 3 and the cryopanel 9 is cooled to about 15K.
After that, the vacuum valve is opened and connected to the vacuum device via the gas inlet 2 to operate the turbo-molecular pump 5. As a result, the gas in the vacuum device flows to the turbo molecular pump 5 through the pump case 1 of the cryopump, and the condensable gas is condensed and discharged to the shield panel 7 and the cryopanel 9, and in particular, condensed gas such as argon gas The low-temperature gas is condensed and exhausted on the surface of the cryopanel 9 facing the gas inlet 2, that is, on the outer surface. But hydrogen,
Non-condensable gas such as helium, neon, etc.
The gas is exhausted by the turbo molecular pump 5 through the gas outlet 2 and the gas outlet 4. Note that almost no gas condenses on the inner surface of the cryopanel 9. Since the gas flow port 12 is formed at a position that is shadowed by the cryopanel 9 and has an area smaller than the projected area thereof, even if the gas condensed on the cryopanel 9 peels off and falls off, the turbo molecular pump 5 There is no danger of falling directly into the inside, and a large amount of condensable gas can be exhausted from the vacuum device. Since the cryopump condenses a large amount of gas and reduces its exhaust capacity, after a suitable use time, a regeneration process for melting the condensed gas is performed. Since the first and second edge portions 13 and 15 are provided, there is no fear of an accident that flows into the turbo molecular pump 5 and freezes until a certain amount of liquefied gas is generated.

Assuming that the volume of the liquefied gas when the gas such as argon condensed in the cryopanel 9 is liquefied is V,
It is sufficient that the volume of the liquid receiving portion 14 of the shield panel 7 is V or more. For example, if the exhaust capacity of argon is 2000 liters (0 ° C., 1 atm), the density of liquid argon is about 1.
4 (g / cm ³ ), the volume when argon is liquefied is about 2550 cm ³ , and the volume of the first liquid receiving section 14 may be 2.55 liter or more. This liquefied gas flows down from the liquefied gas vent hole 17 of the shield panel 7 to the second liquid receiving portion 16 of the pump case 1. This second liquid receiving section 1
The volume of 6 needs only to be V or more, and the liquefied gas accumulated here is discharged to the outside by opening the valve 19.

For regeneration, the vacuum valve 10 between the cryopump and the turbo-molecular pump 5 is closed, the refrigerator 3 is stopped, nitrogen gas is introduced into the pump case 1, or a heater is provided from outside the pump case 1. To melt the condensed gas. And pump case 1
When the internal pressure rises to the atmospheric pressure, the valve 19 is opened, and a low-temperature gas such as argon gas or a liquefied gas is discharged out of the pump case 1. When the gas or liquid such as argon completely disappears in the pump case 1, the introduction of nitrogen and the heating of the heater are stopped, and the valve 19 is closed. The inside of the pump case 1 is evacuated by the turbo-molecular pump 5, and the refrigerator 3 is operated to operate the cryopump. When the temperature of the cryopanel 9 becomes equal to or lower than 20K, the cryopump can start exhausting again. In this regeneration, the condensed gas can be melted without completely returning the inside of the cryopump to room temperature, and when restarting, cooling of the panels 7 and 9 can be started from a low temperature state, shortening the cooling time Yes, there is an advantage that the time until restart is shortened. Further, since only a non-condensable gas such as hydrogen flows into the turbo-molecular pump 5, the gas flow rate to the turbo-molecular pump 5 is small, and the pressure at the high vacuum port 6 can be reduced. A vacuum apparatus using a large amount of condensable gas can be evacuated to a high vacuum using an inexpensive standard turbo molecular pump 5.

The embodiment shown in FIG. 5 is an example in which the hollow portion 9a of the cryopanel 9 is opened upward. In this case, the cryopanel 9 is provided with a hole 21 for venting liquefied gas. For example, a structure in which condensable gas is not condensed on the outer surface of the cryopanel 9 such that a gap between the shield panel 7 and the pump case 1 is narrowed and most of the condensable gas can be condensed and exhausted on the inner surface of the cryopanel 9. Of the cryopanel 9 from the periphery of the cryopanel 9 is determined.
Structure is adopted.

Further, the embodiment shown in FIG. 6 has a hollow portion 9b vertically penetrating the cryopanel 9,
The outer peripheral surface of the cryopanel 9 is provided close to the shield panel 7. In this case, the opening 8 and the gas outlet 4 are provided.
Are confronting each other, some condensable gas such as argon is supplied from the gas outlet 4 to the turbo molecular pump 5.
However, since the quantity is small, an effect substantially equivalent to that of the embodiment of FIG. 4 can be obtained.

The vacuum valve 10 is provided as needed, but is preferably provided to prevent a low-temperature gas in the cryopump from flowing into the turbo molecular pump 5.
The shape of the baffle 11 is arbitrary.

[0017]

As described above, according to the present invention, a cryopanel is provided in a cup-shaped shield panel inside a pump case of a cryopump provided with a gas inlet above, and the turbo molecular pump is connected to the pump case. In the cryopump connected to the gas outlet below the cryopanel, a vertical hollow portion is formed in the cryopanel, and a gas flow smaller than the surface area in the projection surface area of the cryopanel at the bottom of the shield panel. Since the gas outlet is formed below the gas flow port, a vacuum device such as a sputtering device that generates a large amount of condensate in the cryopump can be formed using a standard inexpensive turbo molecular pump. And a first edge and a second edge extending upward around the gas flow opening and the gas outlet. Since the liquefied gas at the time of reproduction can be completed within a short time without inconvenience causing failure flows into the turbo molecular pump, there is an effect such that the arrangement can also be relatively simple and inexpensive to manufacture.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a conventional example.

FIG. 2 is an explanatory view of another conventional example.

FIG. 3 is a sectional view showing a specific structure of FIG. 2;

FIG. 4 is a cutaway side view of an embodiment of the present invention.

FIG. 5 is a cutaway side view of another embodiment of the present invention.

FIG. 6 is a cutaway side view of a third embodiment of the present invention.

[Explanation of symbols]

1 pump case 2 gas inlet 3
Refrigerator 4 Gas outlet 5 Turbo molecular pump 6
High vacuum port 7 Shield panel 8 Opening 9
Cryopanel 9a Hollow part 12 Gas flow port 1
3 1st edge 15 2nd edge 17, 18, 21 Hole for liquefied gas release

Claims (4)

(57) [Claims] 1. A cup-shaped shield panel having an opening to the inlet inside a pump case of a cryopump having a gas inlet above and connected to a refrigerator on a side of the pump case. A cryopanel connected to the refrigerator inside the shield panel, and a high vacuum port of a turbo-molecular pump connected to a gas outlet formed below the pump case. A gas flow opening smaller than the surface area in the projection surface area of the cryopanel at the bottom of the shield panel, and a first edge extending upward around the gas flow opening. A gas outlet of the pump case is formed at a position below the gas flow opening of the shield panel, and a second edge extending upward around the gas outlet is provided. Turbo minutes Cryopump device with a child pump. 2. The cryopanel has a hollow part opened downward, a hole for liquefied gas venting is provided in the shield panel and the bottom part of the pump case, and the gas flow of the pump case is more than the gas flow opening. The cryopump device with a turbo-molecular pump according to claim 1, wherein the outlet has a small diameter. 3. The cryopanel has a hollow portion opened upward, and a liquefied gas vent hole is provided at each bottom of the cryopanel, the shield panel, and the pump case.
2. The cryopump device with a turbo-molecular pump according to claim 1, wherein a gas outlet of the pump case is formed smaller in diameter than the gas flow port. 4. The cryopump device with a turbo-molecular pump according to claim 2, wherein the cryopanel has a hollow portion penetrating vertically.