JPH0830466B2 - How to regenerate a cryopump - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for regenerating a cryopump used for evacuation of a vacuum device.

[Conventional technology and its problems]

A cryopump is a vacuum pump that physically condenses or sorbs a gas on an extremely cooled surface to remove it. The principle of the cryopump will be described below with reference to FIG. In the high vacuum cryopump (21), the helium compressed by the compressor (22) is circulated in the refrigerator (23), and the first cry panel (24) is heated to 100K or less, for example 50K, or 2 Cool the cryopanel (25) at the first stage to 10K to 20K. Further, an adsorbent (26) such as activated carbon is adhered to a part of the second-stage cryopanel (25). A baffle (28) is provided between the cryopump (21) and the vacuum chamber (27). As can be seen from the graph of the saturated vapor pressure of various substances at low temperature attached as Fig. 4, water vapor and carbon dioxide are in the first cryopanel (24), and argon and nitrogen are in the second cryopanel (25). , Oxygen, etc. will condense. Hydrogen, helium, and neon that cannot be exhausted due to condensation at 10K to 20K are sorbed on the adsorbent (26). Since the cryopump is a storage type, when the pump is saturated, stop the operation for regeneration,
Condensate and sorbate must be evaporated and removed by heating.

A conventional method for regenerating a cryopump, which requires a shorter time, will be described below with reference to FIG.

After stopping the refrigerator (46) and stopping the operation of the cryopump (48), the main valve (45) connected to the vacuum chamber (44) is closed. Open the nitrogen gas inlet valve (37) and press the pressure reducing valve (3
Introduce nitrogen gas through 5). Atmospheric pressure check device (38)
When the inside of the pump reaches atmospheric pressure while checking in step 2, open the nitrogen gas release valve (39) to release nitrogen gas. The nitrogen gas used at this time may be room temperature, and the heater (36)
It may be heated up to about 70 ℃. Alternatively, at the same time when the nitrogen gas is introduced, the band heater (33) provided around the pump case (31) is energized to heat the side surface of the pump case (31), and the cryopanel in the pump is generated by radiant heat or heat conduction of gas. In some cases, the temperature rise may be accelerated. Thermometer (4
After confirming that the temperature of the parts inside the pump reached room temperature in 7), close the nitrogen gas introduction valve (37) and the nitrogen gas release valve (39) to stop the introduction and temperature rise of nitrogen gas, Open the roughing valve (40) and perform roughing with the roughing pump (41). When the pressure gauge (42) confirms that the pressure inside the pump has dropped to the specified value, check if there is no gas emission source or leak in the pump. If neither is found, turn on the refrigerator (46). Start and cool the cryopump (48).

According to the above method, all the components in the pump, that is, the first and second stage cryopanels, baffles, etc. are all heated to room temperature, and the heat capacity of all of them is large, so the temperature raising time becomes long. . On the contrary, since all of the temperature is raised to room temperature during cooling, the heat capacity is further increased particularly when the pump case (31) is heated, and a very long cooling time is required. Further, since the temperature is raised to room temperature and the roughing is performed, the time loss due to the roughing is large. Therefore, it took 4 to 5 hours to regenerate the pump as a whole.

[Problems to be solved by the invention]

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 that requires a short time.

[Means for solving problems]

In the method for regenerating a cryopump including a high temperature side cooling unit and a low temperature side cooling unit, a temperature detecting means for detecting the temperature of the low temperature side cooling unit is provided, and the object is provided in the vicinity of the low temperature side cooling unit. It is achieved by a method for regenerating a cryopump, in which only the low temperature side cooling unit is intensively heated to a temperature of 100K to 200K by a heating means while exhausting the inside of the cryopump by a roughing pump. .

[Action]

In the cryopump regeneration method of the present invention, since the heating means is arranged close to the low temperature side cooling section, only the low temperature side cooling section is heated up intensively by the heating means and kept at 100K to 200K. In addition, since the inside of the cryopump is exhausted by the roughing pump while performing such intensive temperature heating, the low temperature side cooling unit is selectively operated while keeping the pressure inside the cryopump below atmospheric pressure. The temperature rise in the cooling section on the high temperature side can be suppressed to a low level.

〔Example〕

Next, examples will be described with reference to the drawings. FIG. 1 shows a configuration example of a cryopump for performing the regeneration method of the present invention, a vacuum chamber connected to the cryopump, and other parts,
FIG. 2 shows an example of the internal configuration of the cryopump of FIG. The 1st side which is the high temperature side cooling part of the refrigerator of the cryopump (1) consists of the 1st stage (15), the shield (10) and the baffle (11), and the 2nd side which is the low temperature side cooling part is 2 stages Stage (12), cryopanel (13), activated carbon (14)
Consists of. The components on each stage are thermally connected to each stage, and when the cryopump is activated, the first stage is cooled to 80K and the second stage is cooled to 15K. 2 stage (12)
A heater (16) for raising the temperature of the second stage is attached to the, and the cord (17) is connected to the outlet (18). Further, a gold-iron / chromel thermocouple (19a) capable of measuring a wide temperature range is attached to the second stage (12) and read by an external thermometer (19b). That is, the temperature detecting means includes a gold-iron / chromel thermocouple (19a) and a thermometer (19b).
It consists of and. Roughing pump (8a) (8b) is the roughing valve (9
It is connected to the manifold (2) of the cryopump (1) via (a) and (9b). The roughing pump (8a) does not have to be an oil-free pump.
A pump capable of roughing up to about 0.1 Torr may be used. In the examples, a combination of rotary pump and mechanical booster pump was used. Alternatively, a turbo molecular pump may be used. The roughing pump (8b) is oil-free, 10 ^-3 Torr
A pump that can exhaust up to the following and has an exhaust capability for hydrogen may be used. A turbo molecular pump is used in the embodiment, but a cryo pump may be used. In order to measure the pressure inside the cryopump (1), the pressure gauge (7a) (7
b) is attached to the manifold (2). One pressure gauge (7a) is capable of measuring high pressures in the 10 ⁻³ Torr range or higher, and the other pressure gauge (7b) is capable of measuring pressures below that. The cryopump (1) is the main valve (5)
To the vacuum chamber (6). (3) is a refrigerator, which is connected to a compressor (not shown) by a helium pipe (4). (20) is a safety valve.

When regenerating the cryopump (1), stop the refrigerator (3) with the main valve (5) and the roughing valves (9a) (9b) closed, and stop the operation of the cryopump,
The heater (16) was energized to heat only the second stage side. Substances such as argon, nitrogen, and oxygen condensed on the cryopanel (13) are gasified and the pressure inside the cryopump (1) rises, so when the pressure gauge (7a) shows 0.3 Torr, the The pulling valve (9a) was opened, and roughing was performed by the roughing pump (8a). Roughing pump (8b) when the pressure inside the pump further rises, reaches the maximum value, then drops and reaches 0.3 Torr again
After that, the raw material was roughly drawn to 1 × 10 ^-3 Torr. Heater (1
Check the thermometer (19b) for the power to 6),
It carried out until it became 200K, and when the target value was reached, the power supply was stopped. Then, after confirming that the pressure did not rise, the cryopump was operated.

By the method described above, the regeneration time, which required about 5 hours in the conventional regeneration method, was reduced to about 1.5 hours. The ultimate pressure when the cryopump was restarted was almost the same as when the conventional regeneration method was used. Therefore, in this embodiment,
It can be said that the same effect as the conventional method was obtained in a short time.

Also, since there is almost no argon gas sorbed on the activated carbon (14) when the cryopump is activated, the sorption speed and sorption capacity of the gas such as hydrogen exhausted by the sorption on the activated carbon (14), that is, the exhaust speed. There was no effect on the exhaust capacity.

The present invention is particularly effective when the gas in the vacuum chamber exhausted by the cryopump is a gas such as argon, nitrogen, oxygen, etc., which is condensed on the second stage side of the refrigerator. These are gasified at 100K or higher during regeneration and easily exhausted outside the cry pump. For regeneration in such a case, it is sufficient to raise the temperature only on the second stage side.

In this embodiment, when only the second stage is heated and the pump internal pressure becomes about 0.3 Torr, roughing is performed by the roughing pump (8a) having a large exhaust speed so that the first stage can be heated as much as possible. This is to keep it low and shorten the time required for playback. Furthermore, the reason why an oil-free pump capable of exhausting up to 10 ^-3 Torr or less is separately used as the roughing pump (8b) is to exhaust the internal pressure of the pump as quickly as possible to a pressure at which vacuum insulation is achieved.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, an electric heater was used to raise the temperature on the second stage, but instead, a capillary tube was wound around the second stage of the refrigerator with good thermal contact, and a heating medium was circulated through the capillary tube. Alternatively, it may be performed by locally irradiating infrared rays on the two-stage stage using an optical fiber, for example.

The temperature of the second stage was raised to 200K, but it may be higher than the temperature at which the argon, nitrogen, oxygen, etc. condensed and sorbed in the second stage during the operation of the cryopump are gasified and desorbed. This time,
Molecules once gasified once again condense and contract to the second stage and reach the saturated vapor pressure or equilibrium pressure depending on the temperature, so the temperature at which the amount of condensation and sorption on the second stage becomes an equilibrium level that can be ignored. If it is above, it is good. Further, it is sufficient if the amount is equal to or higher than the negligible temperature, and the temperature is lower than room temperature as much as possible in order to shorten the cooling down time. This depends on the exhaust speed of the roughing pump (8a).

The cryopump in the present invention also includes a sorption pump.

〔The invention's effect〕

The present invention is configured as described above, and when the cryopump is regenerated, only the second-stage side is heated up intensively, and the temperature of 100K ~
Since the temperature of 200K and the temperature rise on the first stage side can be kept low,
The cooling drop becomes faster when restarting after the end of regeneration. Moreover, since roughing is performed while raising the temperature on the 2nd stage and regeneration is performed at a pressure lower than atmospheric pressure, the pressure drop at the time of restart becomes faster, and the time required for regeneration / restart is 1/3 that of the conventional method. Through 1
It is shortened to / 4.

[Brief description of drawings]

FIG. 1 is a configuration example of an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing an internal configuration example of a cryopump of this embodiment, FIG. 3 is a diagram showing the principle of the cryopump, and FIG. Fig. 5 shows a graph of saturated vapor pressure of various substances in Fig. 5, and Fig. 5 shows a method for regenerating a cryopump by a conventional method. In the figure, (1) ...... Cryo pump (8a) (8b) …… Roughing pump (10) …… Shield (11) …… Baffle (12) …… 2 stage (13) …… Cryo panel (14) …… Activated carbon (15) …… First stage (16) …… Heater

Claims (4)

[Claims] 1. A method of regenerating a cryopump including a high temperature side cooling section and a low temperature side cooling section, wherein temperature detecting means for detecting the temperature of the low temperature side cooling section is provided, and the cryopump is provided close to the low temperature side cooling section. Only the low temperature side cooling unit by the heating means provided,
A method for regenerating a cryopump, which comprises exhausting the inside of the cryopump by a roughing pump while intensively heating to a temperature of 100K to 200K during regeneration. 2. The method for regenerating a cryopump according to claim 1, wherein the heating means is an electric resistance heater. 3. The method for regenerating a cryopump according to claim 1, wherein the heating means is a capillary tube wound around the cooling section on the low temperature side, and a heating medium is circulated in the capillary tube. 4. The method for regenerating a cryopump according to claim 1, wherein the heating means is an optical fiber for irradiating infrared rays.