JP2000192883A - Combined cryopump, and exhaust method and regeneration method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combined cryopump implementing safe regeneration even if mixture of combustible gas and combustion supporting gas is exhausted, and to provide the usage and regeneration method. SOLUTION: In a pump case 3 of cryopumps, which has an exhaust port 2, stages 6 and 7 of a first cryopump 4 are provided upstream, that is, near the exhaust port 2, and exhaust faces 8 communicated to the stages 6 and 7 are provided. Further, through a gate valve 9, stages 10 and 11 of a second cryopump 5 are provided downstream, that is, distance from the exhaust port 2, and exhaust faces 12 communicated to the stages 10 and 11 are provided. The exhaust faces 8 of the first cryopump 4 are arranged so that a person cannot look into an opening downstream of the first cryopump 4 from the exhaust port 2. By the exhaust faces 8 of the first cryopump 4, combustion supporting gas from the exhaust port 2 is condensed and exhausted, and by the exhaust faces 12 of the second cryopump 5, combustible gas from the exhaust port 2 is condensed and exhausted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor film forming apparatus,
The present invention relates to a cryopump applied to evacuation of a vacuum device such as a charged particle injector.

[0002]

2. Description of the Related Art Conventionally, a cryopump is well known. Generally, a cryopump single-stage and a cryopump two-stage cooled to ultra-low temperature and extremely low temperature by a refrigerator are provided in a pump case having an exhaust port. A stage is provided, and a baffle, a shield, a cryopanel, etc. are attached to each stage to form an exhaust surface for condensing gas. Cryopumps have the advantage of being able to exhaust most types of gases.

[0003]

In a vacuum chamber of a vacuum apparatus, a plurality of gases are often used, and in such a case, the plurality of gases are condensed and exhausted in a cryopump. Since the gas molecules condense on the exhaust surface and the exhaust capacity decreases as the thickness increases, the temperature inside the pump case is increased while introducing a purge gas into the pump case, and the condensed gas molecules are evaporated and discharged to the outside. By doing so, the exhaust capacity is regenerated.

[0004] This reproducing method will be described with reference to FIG.
A cryopump c connected to the vacuum chamber a via the main valve b is connected via a purge gas inlet e provided with an opening / closing valve d, an exhaust duct g provided with an opening / closing valve f to the outside, and an opening / closing valve h. A roughing pump i is provided, and upon regeneration, first, each of the valves b, d, f,
h is closed to stop the operation of the cryopump c. Next, the opening / closing valve d is opened, and a purge gas of N ₂ gas is introduced into the pump case of the cryopump through the purge gas inlet port e. When the inside of the pump case becomes atmospheric pressure, the opening / closing valve f is opened and the purge gas is exhausted. The gas molecules condensed on the surface are removed from the exhaust duct g to the outside while evaporating the gas molecules. When the inside of the pump case reaches room temperature, the opening / closing valves d and f are closed, the roughing pump i is started, and the opening / closing valve h is opened, the inside of the pump case is roughly drawn to about 40 Pa, and a pressure rise test is performed. When it is confirmed that there is no leak, the on-off valve h is closed and the operation of the cryopump c is resumed.
Is opened to resume the evacuation of the vacuum chamber a.

[0005] gases exhausted from the vacuum chamber a is, when the evaporating temperature range is gas combustion-supporting gas are mixed, such as combustible gas and O ₂ such as H ₂ in close proximity in both the gas during such reproduction simultaneously It is common to avoid the use of a cryopump and use a turbo-molecular pump that constantly exhausts and discharges to the atmosphere with a dilute gas because it may evaporate and explode or burn. However, compared with a cryopump, a turbo-molecular pump has a pumping speed that is about half that of a cryopump, so that it is necessary to increase the number of installed turbo-molecular pumps. Also, the number of roughing pumps such as dry pumps and mechanical booster pumps is increased. Further, since the back pump of the turbo molecular pump is constantly operated, there is a disadvantage that running costs such as electric power are increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite cryopump capable of safely regenerating even if a mixed gas of a combustible gas and a supporting gas is exhausted, and a method of using and regenerating the same. Is what you do.

[0007]

According to the present invention, a stage of a first cryopump and an exhaust surface connected to the stage are provided in a pump case of a cryopump having an exhaust port on an upstream side close to the exhaust port. A stage of the second cryopump and an exhaust surface connected to the stage are provided via a gate valve on the downstream side away from the exhaust port, and the second cryopump is provided with a stage so that the downstream opening of the first cryopump cannot be seen from the exhaust port. By arranging the exhaust surface of the first cryopump, a mixed gas of a combustible gas and a supporting gas is exhausted, so that the cryopump can be safely regenerated. The second stage of the second cryopump can be provided with an exhaust surface covered with activated carbon. The roughing pump connected to the roughing pump faces the respective exhaust spaces of the first and second cryopumps. A port, a purge gas inlet, and an exhaust duct are provided, and if necessary, the temperature of the exhaust surface of the first cryopump is controlled to be equal to or higher than the temperature of the exhaust surface of the second cryopump.

At the time of exhaustion, the combustion supporting gas from the exhaust port is condensed and exhausted by the exhaust surface of the first cryopump,
Preferably, the combustible gas from the exhaust port is condensed and exhausted by the exhaust surface of the second cryopump.

Further, in the composite cryopump of the present invention, after closing the exhaust port, the gate valve is closed, and then the operation of the second cryopump is stopped to introduce a purge gas into the exhaust space to atmospheric pressure. When the atmospheric pressure is reached, the purging gas is continuously introduced while the exhaust space is communicated with the outside. When the temperature of the second cryopump reaches the first set temperature, the operation of the first cryopump is stopped and the exhaust gas is exhausted. A purge gas is introduced into the space until the pressure reaches the atmospheric pressure. When the exhaust space of the first cryopump reaches the atmospheric pressure, the purge gas is continuously introduced while communicating the exhaust space to the outside,
When the temperature of the second cryopump reaches the second set temperature higher than the first set temperature, the introduction of the purge gas into each exhaust space and the communication with the outside are stopped, and each exhaust space is evacuated by the roughing pump. By evacuating, it can be safely regenerated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.
2 and 3 show the flammable gas H _TwoAnd flammability
Gas O_TwoIs an embodiment for separating and exhausting the gas.
A composite cryopump having an exhaust port 2 and a cryopump 3
2 shows a cylindrical pump case of the pump 1. The composite cry
Opump 1 is composed of first and second cryopumps 4 and 2
And the exhaust port 2 in the pump case 3
The cryo-poof of the first cryopump 4
Pump first stage 6 and cryopump second stage 7
As well as exhaust air that is heat conductively connected to these stages
A surface 8 is provided to form an exhaust space 20, which is remote from the exhaust port 2.
A gate bar is provided on the downstream side, that is, the back side of the pump case 3.
Cryopump of the second cryopump 5 through the lube 9
1-stage stage 10 and cryopump 2-stage stage 11
As well as exhaust air that is heat conductively connected to these stages
The exhaust space 21 was formed by providing the surface 12.

To explain this further, the first cryopump 4 is for obtaining a low temperature by a refrigeration cycle using gaseous helium or the like. 80K
And the cryopump second stage 7 is cooled to an extremely low temperature of, for example, 20K. The first stage 6 has a blade-shaped baffle 1 connected by brazing or the like.
And an exhaust surface 8 composed of a cryopanel 16 by brazing or the like on the two-stage stage 7, and a pump case from the vacuum chamber of a vacuum device connected to the exhaust port 2. Some of the gas coming into 3
The air is condensed on these exhaust surfaces 8 and exhausted. In addition, these exhaust surfaces 8 do not look into the opening 17 on the downstream side of the first cryopump 4 when viewed from the upstream side of the exhaust port 2, that is, go straight from the upstream side of the exhaust port 2. The inclination angle and arrangement of the baffle 14, the shield 15, and the cryopanel 16 are set so that gas molecules cannot pass through.

The baffle 14 and the shield 15 are cooled to about 80K, which is substantially the same temperature as the first stage 6, and the cryopanel 16 is cooled to 20K, which is substantially the same temperature as the second stage 7. When a mixed gas of H ₂ O, O ₂ (combustible gas) and H ₂ (combustible gas) flies to the exhaust port 2, first, H ₂ O forms a baffle 14 and a shield 15.
O ₂ is condensed in the cryopanel 16 and exhausted. However, the flammable gas H ₂ has a low condensation temperature and cannot be exhausted even by the cryopanel 16, and enters the exhaust space 21 of the second cryopump 5 via the gate valve 9.

The second cryopump 5 has basically the same structure as the first cryopump 4, obtains a low temperature by a refrigeration cycle using helium gas or the like, and has a single-stage cryopump by a dedicated refrigerator 18. The stage 10 is cooled to an extremely low temperature of, for example, 80 K, and the cryopump second stage 11 is cooled to, for example, a very low temperature of 20 K. The blade stage baffle 2 is attached to the first stage 10 by brazing or the like.
4 and a shield 25 are provided.
Cryopanel 26 by brazing on stage 11
An exhaust surface 12 is provided. Further, the blade-shaped baffle 24 can be removed if necessary. The difference between the second cryopump 5 and the first cryopump 4 is that the second cryopump 5 is configured to be able to condense and exhaust combustible gas.
In the illustrated example, the surface of the cryopanel 26 is coated with a layer 27 of activated carbon in order to exhaust H ₂ that cannot be condensed and exhausted even at 20K.
And the H ₂ molecules incident on the exhaust space 21 without being exhausted by the first cryopump 4 are condensed and exhausted.

The two cryopumps 4, 5 face each exhaust space 20, 21 communicating with each other through a gate valve 9.
₂ purge gas inlets 28 for introducing gases, etc.
9. Exhaust ducts 30 and 31 for removing gas from the exhaust spaces 20 and 21 to the outside, and roughing ports 32 and 33 for connecting roughing pumps are provided, so that each pump can be regenerated. The gate valve 9 has a well-known structure in which the valve plate 34 is operated by an actuator 35 such that the communication between the two cryopumps 4 and 5 is interrupted. Sometimes, the first cryopump 4 is closed while being pressed against and in contact with the opening 17 on the downstream side of the first cryopump 4.

In the above description, the first and second cryopumps 4 and 5 are both provided with two stages. However, the first cryopump 4 has an 80K cryopump first stage 6. And the second cryopump 5 is provided with two-stage stages 10 and 11 as shown in FIGS. 2 and 3 or a two-stage stage 11. Only, the temperature of the exhaust surface 8 of the first cryopump 4 may be higher than the temperature of the exhaust surface 12 of the second cryopump 5. According to this configuration, NH ₃ (combustible gas) and O ₂ (combustible gas) in the vacuum chamber can be separated and exhausted, and NH ₃ is exhausted on the exhaust surface 8 of the first cryopump 4. O at the 20K exhaust surface 12 of the second cryopump 5
₂ can be exhausted.

After the evacuation time has elapsed, each cryopump
A thick layer of condensed gas is formed on the exhaust surfaces 8 and 12 of 4, 5
It grows and exhaust capacity decreases, so it needs to be regenerated
However, in the composite cryopump of the present invention, as shown in FIG.
As described above, each purge gas is introduced through the opening / closing valves 36 and 37.
N in mouths 28 and 29_TwoConnect a purge gas source such as a gas source,
Via the open / close valves 38, 39 to the exhaust ducts 30, 31
Communicate with the outside, and further open the roughing ports 32 and 33
Connected to roughing pumps 42 and 43 via lugs 40 and 41
And prepare for playback. Exhaust surface of first cryopump 4
8 at H_TwoO, O_TwoAnd exhaust of the second cryopump 5
H at surface 12_TwoWhen exhausting air, connect the exhaust port 2 to the vacuum chamber.
Close the open / close valve 44 and the gate valve 9 of the passage, and first,
The operation of the second cryopump 5 is stopped, and the exhaust space 2
1 to N from the purge gas inlet 29 _TwoIntroduce purge gas
Enter. When the exhaust space 21 reaches atmospheric pressure,
Open the air outlet 39 to the outside from the exhaust duct 31
H evaporating from_TwoGas N_TwoPurge with gas. And the second
The temperature of the stage of the 2 cryopump 5 is, for example, 120 K
When the time exceeds 1, stop the operation of the first cryopump 4 and
N through the purge gas inlet 28 into the exhaust space 20_Twoetc
Purge gas until atmospheric pressure is reached.
Open the open / close valve 38 and evaporate from the exhaust surface 8
O_TwoOr H depending on the temperature_TwoO is also N_TwoPurge with
You. After this purge, the temperatures of both pumps 4 and 5 reach room temperature.
After that, stop the playback and restart each
The pumps 42 and 43 are activated and the exhaust spaces 20 and 21
Start roughing and check for leaks in the pressure rise test.
When it is confirmed, the refrigerators 13 and 18 are started and each stage is cooled.
And when the temperature reaches a predetermined temperature, the opening / closing valve 44 is opened.
And start evacuation of the vacuum chamber. In this case, the flammable H_Two
And oxidizing O_TwoAre exhausted separately and do not mix
No need to worry about burning or explosion
Consideration of the degree of reparation can maintain the safety of regeneration. In addition, the first
NH on exhaust surface 8 of liopump 4_ThreeAnd exhaust the second
O at the exhaust surface 12 of the Io pump 5_TwoAlso when exhausting
It can be played back by the playback method.

The above is a regeneration method for raising the temperature to room temperature. However, if the temperature is raised to about 200K, low-temperature regeneration in which roughing is performed is also possible.

Further, by setting the second cryopump 5 to the atmospheric pressure and then setting the first cryopump 4 to the atmospheric pressure, the valve plate 34 of the gate valve 9 opens the first cryopump 4 due to the pressure difference between before and after. 17, gas leakage does not easily occur from the exhaust space 20 of the first cryopump 4 to the exhaust space 21 of the second cryopump 5, and safety is improved.

[0019]

As described above, according to the present invention, the first cryopump is provided in the pump case of the cryopump via the gate valve on the upstream side close to the exhaust port and on the downstream side away from the exhaust port. Stage and exhaust surface and second
The stage and the exhaust surface of the cryopump are provided, and the exhaust surface of the first cryopump is arranged so that the exhaust port cannot look into the opening on the downstream side of the first cryopump. The first and second cryopumps are separated and exhausted by the first and second cryopumps, and the first and second cryopumps can be individually and safely regenerated by closing the gate valve. There is an effect that the mixed gas of the flammable gas can be quickly and safely exhausted at a low running cost, the structure thereof can be manufactured relatively simply and inexpensively, and the object of the present invention can be further enhanced by adopting the structure of claims 2 and 3. It can be achieved reliably, and the regeneration can be performed safely by separating and exhausting by the method of claim 4. By the regeneration method of claim 5, the regeneration can be performed safely and quickly without mixing the condensed gas of the first and second cryopumps. There is an effect of.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a conventional cryopump regeneration method.

FIG. 2 is a plan view showing an embodiment of the present invention.

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is an explanatory diagram of a reproducing method according to the present invention.

[Explanation of symbols]

Reference Signs List 1 composite cryopump, 2 exhaust port, 3 pump case, 4 first cryopump, 5 second cryopump, 6.10 cryopump 1 stage, 7/11
Cryopump 2 stage, 8 ・ 12 Exhaust surface, 9
Gate valve, 17 openings, 20/21 exhaust space,
26 cryopanel, 27 layer of activated carbon, 28/29
Purge gas inlet, 30/31 exhaust duct, 32 /
33 roughing port, 42/43 roughing pump,

Claims (6)

[Claims] 1. A stage for a first cryopump and an exhaust surface connected to the stage are provided in the pump case of a cryopump having an exhaust port on the upstream side close to the exhaust port, and the downstream side is remote from the exhaust port. A stage of the second cryopump and an exhaust surface connected to the stage are provided via a gate valve, and the exhaust surface of the first cryopump is so arranged that the exhaust port cannot look into the downstream opening of the first cryopump. A composite cryopump characterized by being arranged. 2. The composite cryopump according to claim 1, wherein an exhaust surface covered with activated carbon is provided on a second stage of said second cryopump. 3. A roughing port connected to a roughing pump, a purge gas inlet and an exhaust duct are provided facing the respective exhaust spaces of the first and second cryopumps. Item 3. A composite cryopump according to item 2. 4. The temperature of the exhaust surface of the first cryopump is equal to or higher than the temperature of the exhaust surface of the second cryopump. Composite cryopump. 5. A composite cryopump having a configuration according to any one of claims 1 to 4,
A complex characterized in that the exhaust surface of the first cryopump condenses and exhausts the supporting gas from the exhaust port, and the exhaust surface of the second cryopump condenses and exhausts the combustible gas from the exhaust port. Exhaust method using a cryopump. 6. A first cryopump stage and an exhaust surface connected to the stage are provided in a pump case of a cryopump provided with an exhaust port on an upstream side close to the exhaust port, and a downstream side is separated from the exhaust port. A stage of the second cryopump and an exhaust surface connected to the stage are provided via a gate valve, and the exhaust surface of the first cryopump is so arranged that the exhaust port cannot look into the downstream opening of the first cryopump. When regenerating the placed composite cryopump,
After closing the exhaust port, the gate valve is closed, then the operation of the second cryopump is stopped, and a purge gas is introduced into the exhaust space to atmospheric pressure. When the temperature of the second cryopump reaches the first set temperature, the operation of the first cryopump is stopped, and the purge gas is introduced into the exhaust space until the pressure reaches atmospheric pressure. When the exhaust space of the first cryopump reaches atmospheric pressure, the purge gas continues to be introduced while communicating the exhaust space to the outside, and the second and third cryopumps have a second set temperature higher than the first set temperature. When the pressure reaches the maximum, the introduction of the purge gas into each exhaust space and the communication with the outside are stopped, and each exhaust space is evacuated by a roughing pump. Method.