JPH06154505A - Method for regenerating cryopump - Google Patents

Abstract

PURPOSE:To drastically shorten a time for regenerating a cryopump and to enhance a net working rate of equipment by discharging gas condensed in the cooling part of the cryopump as liquefied gas to the outside of a pump vessel. CONSTITUTION:One end of a drawing pipe 12a penetrates the bottom part of a pump vessel 2 in the bottom part of the right side thereof and is provided in the vertical direction in order to draw liquefied gas stored in the bottom part of a 80K shield 4 in the pump vessel 20. The bottom part and the drawing pipe 12a are connected airtightly for the outside air. Further the upper end part of the drawing pipe 12a is so connected to the bottom part of the pump vessel 2 that leak is not caused. A cylindrical discharge port 4b is formed in the bottom part in right direction side of the 8OK shield 4. The drawing pipe 12a is inserted into the end part of the discharge side of the discharge port 4b. Accordingly, since gas condensed in the cooling part of a cooling part is not raised. Rise in temperature at a time of regeneration and a cooling time are together shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating a cryopump which can shorten the regenerating time.

[0002]

2. Description of the Related Art A cryopump having a high temperature side cooling section and a low temperature side cooling section cooled by a small helium refrigerator is used for many vacuum exhaust operations. As shown in FIG. 5, in this type of cryopump 20, the tubular pump container 2 is attached to the helium refrigerator 3 and the pump container 2
A cooling section on the high temperature side, that is, a 80K shield 4 and a baffle 6 (80K) arranged above it are provided inside the cooling section, and a cooling section on the low temperature side, that is, the cryopanel 5 is provided inside thereof.
(15K) is provided.

With such a structure, the cryopump condenses various gases to be exhausted on the 80K shields 4, 5 and the baffle 6 or adsorbs them on the adsorbent 9 provided inside the cryopanel 5 and stores them. Since it is a vacuum pump that exhausts gas, if the amount of accumulated gas increases, the amount of exhaust decreases, and the ultimate pressure cannot be obtained.Therefore, it is necessary to derive the accumulated gas and exhaust it again. Playback operation is required.

Particularly, since a large amount of argon gas is exhausted in the sputtering apparatus, the cryopanel 5 as shown in FIG.
The outer surface of is covered with condensed and solidified argon a. As a method of removing the condensed and solidified argon a at the time of regeneration, the refrigerator 3 is stopped and the cryopanel 5 is heated to room temperature,
The argon is vaporized and removed in a gas state by discharging it outside the pump container 2. As a method of raising the temperature of the cryopump 20 to room temperature, a heater or the like is attached to the outer surface of the pump case 2 of the cryopump 20 and heating is performed from the outside, or an inert gas such as nitrogen is introduced into the pump case 2, There is a method of heating and raising the temperature by the amount of heat of the heated gas. Further, as an efficient regeneration method, the above-mentioned heater and gas introduction are used together.

Among these methods, the gas introduction method is shown in FIG. 5 in which a gas introduction pipe 11a and a gas derivation pipe 12a are attached to the inside of the pump container 2 of the cryopump 20 to remove nitrogen or the like heated from the gas introduction pipe 11a. When the inert gas is introduced into the pump container 2 and the temperature inside the container 2 rises, the condensed and solidified gas is vaporized, and is led out of the pump container 2 together with nitrogen from the gas outlet pipe 12a to be removed. Gases with a high vapor pressure, such as argon, nitrogen, and hydrogen, are completely vaporized if the temperature inside the pump container 2 has risen to room temperature, and are therefore discharged outside the pump container 2 together with the introduced nitrogen gas. .

The time spent for reproduction by this method will be described with reference to FIG. For example, when using a 12-inch cryopump and evacuating with 1000 std.liter of argon, as shown by the thin line in the figure, 80K shield 4, 5
It takes about 85 minutes to heat up the temperature to about 300K, 5 minutes for rough evacuation, and 95 minutes for cooling again (time until the cryopanel 5 reaches 20K.), For a total of 185 minutes. Spending.

[0007]

As described above, in the regeneration of the cryopump, when the temperature of the cryopump is raised to room temperature and the condensed and solidified gas such as argon is discharged, the temperature is raised from an extremely low temperature to room temperature. Therefore, it takes time to raise the temperature, and a great amount of time and energy are required to melt and evaporate a large amount of condensed gas such as argon. Also, since the temperature inside the pump container 2 is raised to room temperature during cooling, it takes a long time to regenerate and cool.
In other words, in order to regenerate a cryopump in which a large amount of gas is condensed and accumulated, it is necessary to introduce a large amount of inert gas for melting and evaporation, and to heat and cool the inside of the pump container. However, there was a drawback that it took more than 3 hours to complete the regeneration work, and the device could not be operated during this regeneration.

In addition to this, the liquefied gas that has melted and dropped from the cryopanel to the 80K shield drops to the inner wall of the pump container through a hole for a nitrogen gas introduction pipe opened in the shield and cools the pump container. I will end up. When the pump case cools, dew condensation forms on the outer surface, causing a large amount of water droplets to wet the equipment below. This water content may cause a short circuit in an electric circuit, poor insulation, and may cause rust in equipment.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for regenerating a cryopump, which remarkably shortens the regenerating time as compared with the conventional method. .

[0010]

The above object is to regenerate a cryopump that has a cooling section cooled by a refrigerator in a pump container and regenerates by raising the temperature of the gas condensed in the cooling section. In the method, it is achieved by a method for regenerating a cryopump, characterized in that the condensed gas is discharged to the outside of the pump container in a liquefied gas state in the cooling unit.

[0011]

[Operation] Since the gas condensed in the cooling section of the cryopump is discharged outside the pump container in the state of liquefied gas, the cooling section does not rise to room temperature, so the temperature rise time during regeneration is small. Complete. Moreover, since the temperature of the cooling unit is not raised to room temperature, the cooling time for cooling the cooling unit can be reduced. Therefore, it is possible to shorten both the temperature rising time and the cooling time during regeneration, and it is possible to greatly shorten the regeneration time of the cryopump.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of regenerating a cryopump according to a first embodiment of the present invention will be described below with reference to the drawings. still,
The same components as those of the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, the cryopump according to this embodiment is designated by 1 as a whole, and a helium refrigerator 3 is provided with a tubular pump container 2 having a flange portion 2a. In this refrigerator 3, a first stage freezing stage 7 and a second stage freezing stage 8 provided adjacent to a low temperature expansion chamber provided therein are inserted into the pump container 2. It is attached. Further, inside the pump container 2, there is provided a cooling unit that is cooled by the freezing stages 7 and 8 by heat conduction. The structure of this cooling unit will be briefly described. Inside the pump container 2, an 80K shield 4 made of a thin plate oxygen-free copper or a metal plate made of aluminum and a cryopanel 5 are arranged. 80K outside
The shield 4 is formed in the shape of a cup, is arranged upward on the first stage freezing stage 7, and the baffle 6 is provided at the upper end thereof.

A cryopanel 5 is formed in a cup shape inside the 80K shield 4 and is arranged downward on the second stage freezing stage 8. Further, inside the cryopanel 5, an adsorbent 9 such as activated carbon or molecular sieves is used.
Is provided.

At the bottom of the pump container 2 on the left side, one end of a gas introduction pipe 11a for introducing nitrogen gas is provided so as to penetrate through this bottom and a cylinder portion 4a provided at the bottom of the 80K shield 4. There is. The gas introducing pipe 11a is arranged at the bottom of the pump container 2 in an airtight manner with the outside air, and has a slight gap s between the 80K shield 4 and the cylindrical portion 4a. The connecting portion between the 80K shield 4 and the cylindrical portion 4a is processed so as not to leak. The introduction pipe 11a is connected to a nitrogen gas supply source (not shown) via a pipe 11b and a gas adjusting valve 13. The gas adjustment valve 13 adjusts or stops the supply amount of nitrogen gas introduced into the pump container 2 by the adjustment.

On the other hand, at the bottom of the pump container 2 on the right side, one end of a lead-out pipe 12a for leading out the liquefied gas stored in the bottom of the 80K shield 4 in the pump container 2 penetrates the bottom and is vertically arranged. The bottom portion and the outlet pipe 12a are arranged airtight with the outside air. The upper end portion of the outlet pipe 12a is connected to the bottom portion of the pump container 2 at this connecting portion so as not to leak. In addition, a cylindrical discharge port 4b is formed on the bottom of the 80K shield 4 on the right side, and the discharge side end of this discharge port 4b is inserted into the outlet pipe 12a. The outlet pipe 12b is provided. The outlet valve 14 opens and closes to deliver and stop liquefied gas and nitrogen gas. The bottom of the 80K shield 4 has a through hole formed in the cylindrical portion 4a and a discharge port 4b.
Only the holes are opened and no other unnecessary holes are formed.

In the cryopump 1 thus constructed, the flange portion 2a of the pump container 2 is connected to a vacuum device (not shown), and a compressor for circulating a refrigeration cycle is connected to the outside of the cryopump 1. ing. In addition, 80K shields 4, 5 are provided in the pump container 2.
A temperature sensor is provided to detect the temperature such as.

The cryopump 1 used in the method for regenerating a cryopump according to the first embodiment of the present invention is constructed as described above. Next, the method will be described.

After depressurizing (rough evacuation) to a predetermined pressure in a vacuum device (not shown) to which the cryopump 1 is attached, the refrigeration cycle of the cryopump 1 is started. As a result, the first stage freezing stage 7 and the second stage freezing stage 8 are each cooled to a predetermined temperature.
The desirable temperature of the 80K shield 4 is 70K to 90K, and the cryopanel 5 is 10K to 20K.

When the inside of the vacuum apparatus is evacuated and, for example, sputtering is carried out in a vacuum chamber (not shown), the main component of the gas to be evacuated in the sputtering is argon, and it is almost unnecessary to evacuate the water content. As described above, the argon a is condensed and solidified on the cryopanel 5. When the cryopump 1 operates in this way and the gas is condensed and solidified on the cryopanel 5, and the amount of these increases, the exhaust speed of the gas may decrease or the ultimate pressure may not be obtained. It will be necessary to regenerate.

The reproducing method will be described below. When the operation of the cryopump 1 is stopped and the gas adjusting valve 13 is opened, room temperature or heated nitrogen gas is introduced into the pump container 2 which is a substantially vacuum space. The boiling point of argon is 87.
Since the temperature is 3 K, if the temperature is raised to a temperature higher than this, the condensed and solidified argon can be liquefied. When argon a is liquefied, it falls from the cryopanel 5 to the bottom of the 80K shield 4 by the action of gravity. The 80K shield 4 has a cup-like shape as described above, and the gas introduction pipe 11
Since the tubular portion 4a is formed at the introduction portion of a, the liquefied gas A of argon does not drop from here to the inner wall of the pump container 2 unlike the conventional case.

After the liquefied gas has dropped to the bottom of the 80K shield 4 and until it is led out from the outlet pipe 12a, the 80K shield 4 is kept at a temperature near the boiling point of the liquefied gas A with all or part of the liquefied gas A. This means that the baffle 6 and the portion of the 80K shield 4 that is not in direct contact with the liquefied gas A other than the bottom portion of the 80K shield 4 are maintained at a low temperature by heat conduction, and are cooled to room temperature as in the conventional case. The temperature is not raised. Since water does not condense on the 80K shield 4 in spatter, it is not necessary to exhaust water.
Since it is not necessary to raise the temperature of the 80K shield 4, it is not necessary to raise the temperature above this temperature. In the actual measurement example with this liquefied gas A of argon, the temperature of the 80K shield 4 is 100K.
It was ~ 110K. The liquefied gas A discharged from the outlet pipe 12a is discharged to another safe place through the valve 14 and the outlet pipe 12b.

When the solid or liquefied gas A of argon is completely discharged from the bottoms of the cryopanel 5 and the 80K shield 4, the inside of the pump container 2 is immediately roughly pulled by a rotary pump (not shown) or another vacuum pump. As a result, vacuum heat insulation in the pump container 2 is achieved, so
The temperature of the 0K shield 4, the cryopanel 5 and the baffle 6 rises only up to the boiling point of the liquefied gas or a temperature slightly higher than that. The inside of the pump container 2 is evacuated,
When the temperature reaches about 10 ⁻³ Torr, the cryopump 1 is started, and when the temperature of the cryopanel 5 is cooled to 20K or less, the regeneration is completed. As described above, during cooling, cooling is started at a temperature of about the boiling point of the liquefied gas of argon or a temperature slightly higher than that, so that the cooling time can be greatly shortened.

The nitrogen gas introduced into the pump container 2 is led out together with the liquefied gas A from the lead-out pipe 12a. The amount of the liquefied gas A led out is determined by the diameter of the cylindrical discharge port 4b. . That is, 80K if the diameter of the outlet is small
It easily collects on the bottom of the shield, and if the diameter is large, it does not collect easily. As shown in the figure, when the liquefied gas A is accumulated at the bottom of the 80K shield 4, it passes through between the 80K shield 4 and the inner wall of the pump container 2 and is exhausted from the outlet pipe 12a.

As described above, according to this embodiment, 80K
Since the regeneration is performed without raising the temperature of the shield 4, the cryopanel 5 and the baffle 6 to a high temperature as in the conventional case, the temperature raising time and the cooling time can be greatly shortened. This will be described in comparison with the conventional method in FIG. 6 described above. In this example, the temperature rise and the derivation of the condensed and solidified gas were completed in 20 minutes as shown by the thick line. In the conventional case, it takes 85 minutes, which is a reduction of 65 minutes. The rough evacuation time is 5 minutes as in the conventional method, and the cryopanel 5 is 20K during cooling.
It took 20 minutes. In the past, it took 95 minutes, which is a reduction of 75 minutes. The total required time for reproduction was 45 minutes in this example and 185 minutes in the conventional method, which is a reduction of 140 minutes. Further, since the temperature of the 80K shield 4 is also kept low, the time can be shortened to the same level or higher. As described above, in this embodiment, the reproduction can be completed in 1/3 the time as compared with the conventional method.

As described above, in the present embodiment, the regeneration time of the cryopump 1 can be greatly shortened, so that the operation rate of the apparatus is greatly improved. Further, the liquefied gas does not leak to the inner wall of the pump container 2, dew condensation does not occur on the outer wall of the pump container 2, and the electric components arranged below the pump container 2 are not short-circuited by moisture, It will not corrode.

Next, a method of regenerating the cryopump according to the second embodiment of the present invention will be described with reference to FIG.
The parts corresponding to those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 2, the cryopump used in the method for regenerating the cryopump of this embodiment is indicated by 21 as a whole. In the first embodiment, the gas introducing pipe is arranged on the bottom wall portion of the pump container 2. In the second embodiment, the gas introducing pipe 23a is attached to the peripheral wall portion of the pump container 22.
That is, one end of the gas introduction pipe 23a is arranged so as to penetrate through the hole 22b provided in the peripheral wall portion of the pump container 22 and the hole 24a provided in the 80K shield 24, and the gas introduction pipe 23a and the hole 22b are separated from each other. The gas introduction pipe 23a and the hole 24a of the 80K shield 24 are connected so as to be air-tight.
And are arranged with a gap. In addition, the gas introduction pipe 2
The other end of 3a is provided with a gas adjusting valve 13 and a gas introducing pipe 23.
It is connected to a nitrogen gas supply source (not shown) with b interposed. It should be noted that the bottom of the 80K shield 24 is provided with only a hole for a cylindrical outlet 24b formed therein, and no other unnecessary holes are formed.

The configuration of the cryopump 21 used in the method for regenerating the cryopump according to the second embodiment of the present invention has been described above. However, in the second embodiment, the regeneration can be performed in the same manner as in the first embodiment. It is obvious that the same effect as the first embodiment is obtained.

Next, a method of regenerating a cryopump according to the third embodiment of the present invention will be described with reference to FIG.
The parts corresponding to those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 3, the cryopump used in the method for regenerating the cryopump of the present embodiment is indicated by 31 as a whole, and the drawing shows that the cryopump 31 is connected to the vacuum device 30. The flange portions 30b and 32a formed in the opening are connected. In the first embodiment, the gas introduction pipe for nitrogen gas is arranged on the bottom wall portion of the pump container, but in this embodiment, the gas introduction pipe 33a is attached to the peripheral wall portion of the vacuum device 30. That is, one end of the gas introduction pipe 33 a is arranged so as to penetrate through the hole 30 a provided in the peripheral wall portion of the vacuum device 30, and the gas introduction pipe 3 a
3a and the hole 30a are connected so as to be airtight with the outside air. The other end of the gas introduction pipe 33a is connected to a nitrogen gas supply source (not shown) with the gas adjustment valve 13 and the gas introduction pipe 33b interposed. It should be noted that the bottom of the 80K shield 34 is provided with only a hole for the cylindrical discharge port 34b formed therein, and no other unnecessary hole is formed.

The structure of the cryopump 31 used in the method for regenerating a cryopump according to the third embodiment of the present invention has been described above. In this embodiment, the nitrogen gas for regeneration flows from the vacuum device 30 into the pump container 32. Argon a introduced and condensed and solidified in the cryopanel 5 is liquefied, but also in this embodiment, since the liquefied gas is collected at the bottom of the 80K shield 34 and is discharged from the discharge pipe 12a, the first embodiment is different from the first embodiment. It is clear that the same effect is achieved.

Next, a method of regenerating a cryopump according to a fourth embodiment of the present invention will be described with reference to FIG.
The parts corresponding to those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the first to third embodiments, the cryopump is regenerated by introducing nitrogen gas into the pump container through the gas introduction pipe, but the regenerating method of the cryopump of the fourth embodiment is This is a method of regenerating the cryopump using a heater without using nitrogen gas to raise the temperature of the cryopanel. That is, in the cryopump 41 used in the method for regenerating the cryopump of the fourth embodiment, the heater 45 is attached above the inner wall portion of the 80K shield 4 arranged in the pump container 42 to heat the cryopump. A lead wire 45a is connected to the heater 45, and the lead wire 45a is connected to a power source provided outside although not shown. Further, in this embodiment, a pipe for introducing nitrogen gas is not connected, and a cylindrical discharge port 44b formed at the bottom of the 80K shield 44 is formed.
Only the holes of the above are opened, and no other unnecessary holes are formed.

The configuration of the cryopump 41 used in the method for regenerating the cryopump according to the fourth embodiment of the present invention has been described above. Next, the method for regenerating the cryopump 21 will be described.

In this embodiment, when a voltage is applied to the heater 45 from a power source (not shown), the temperature of the cryopanel 5 rises, and the argon gas a condensed and solidified therein is heated.
Liquefies. The liquefied argon a drops and accumulates at the bottom of the 80K shield 44 by the action of gravity. Since the liquefied gas A of argon keeps the 80K shield 44 and the baffle 6 at a low temperature by heat conduction, it is clear that the fourth embodiment also has the same effect as the first embodiment.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications can be made based on the technical idea of the present invention.

For example, in each of the above embodiments, the bottom of the 80K shield is a horizontal plane, but a gradual inclination may be added to this to let out the liquefied gas. If the slope of the bottom is large, the speed at which the liquefied gas is discharged becomes faster, so 80K
The shield may not be cooled so much, but in such a case, the diameter of the cylindrical discharge port may be reduced.

Further, in the first embodiment described above, it was explained that the temperature of the 80K shield 4 was 100K to 110K as an actual measurement example, but this temperature differs depending on the temperature and the amount of introduction of the nitrogen gas for heating. In the present invention, even if the temperatures of the 80K shield and the baffle are higher than that, for example, about 200K, the effects of the present invention are sufficiently exhibited.

In each of the above embodiments, nitrogen gas or a heater is used to raise the temperature in the pump container, but it is of course applicable to a cryopump that uses both of them.

In each of the above embodiments, the gas condensed in the cryopanel 5 is explained as condensing only argon, but N ₂ , CO, and
It can also be applied to the adhesion of other gases such as O ₂ .
Usually, a cryopump uses an adsorbent, but it can also be applied to a cryopump that does not use an adsorbent.

[0042]

As described above, according to the method for regenerating a cryopump of the present invention, it is possible to significantly shorten the regenerating time in regenerating the cryopump as compared with the conventional method, and to improve the operating rate of the apparatus. Can be improved. Also, the amount of heat energy used for regeneration can be saved.

[Brief description of drawings]

FIG. 1 is a schematic partially cutaway front view of a main part of a cryopump according to a first embodiment of the present invention.

FIG. 2 is a schematic partially cutaway front view of a main part of a cryopump according to a second embodiment of the present invention.

FIG. 3 is a schematic partially cutaway front view of a main part of a cryopump according to a third embodiment of the present invention.

FIG. 4 is a schematic partially cutaway front view of a main part of a cryopump according to a fourth embodiment of the present invention.

FIG. 5 is a schematic partially cutaway front view of a main part of a conventional cryopump.

FIG. 6 is a graph showing a difference in reproduction time consumed between this embodiment and the conventional method.

[Explanation of symbols]

 1 cryopump 2 pump container 3 refrigerator 4 80K shield 5 cryopanel 6 baffle 21 cryopump 22 pump container 24 80K shield 31 cryopump 32 pump container 34 80K shield 41 cryopump 42 pump container 44 80K shield

Claims (2)

[Claims] 1. A method for regenerating a cryopump, comprising a cooling section cooled by a refrigerator in a pump container, and regenerating the gas condensed in the cooling section by raising the temperature, wherein the condensing section is provided in the cooling section. A method for regenerating a cryopump, which comprises discharging the generated gas in a liquefied gas state outside a pump container. 2. The method for regenerating a cryopump according to claim 1, wherein the liquefied gas is accumulated at the bottom of the cooling unit, and the liquefied gas is discharged from the bottom of the cooling unit.