JPH06346848A - Regenerating cryopump method and evacuation system thereof - Google Patents

Abstract

PURPOSE:To mainly reduce regeneration time by forcibly increasing temperature of a cryopanel, and keeping the pressure. inside a cryopump lower than the evaporation pressure of the gas whose saturated vapor pressure is lowest among the gases trapped by the cryopanel. CONSTITUTION:A cryopump 1 used for evacuating a vacuum treatment chamber 15 has a cryopanel 3 for condensing air inside a vacuum chamber 2. The cryopanel 3 is provided with an activated carbon 4, and is cooled by a cooling part 5. Purge gas is introduced from a heater 12 through a valve 11 and a piping 10 to the cryopump 1 for forcibly increasing the temperature of the cryopanel 3. A roughing vacuum pump 9 is operated at the same time. The pressure inside the cryopump 1 is kept lower than evaporation pressure of gas whose saturated vapor pressure is lowest among the gases trapped in the cryopanel 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum technique used for vacuum processing of a semiconductor product manufacturing apparatus or the like.
It is particularly effective when used for handling cryopumps.

[0002]

2. Description of the Related Art In recent semiconductor manufacturing processes, particularly in semiconductor substrate processing technologies such as ion implantation technology and sputtering technology, which perform processing in a vacuum, the quality of the vacuum has a great influence on the product yield as the semiconductor device becomes finer. Has started to give. In addition, high vacuum equipment has become expensive, and high-speed vacuum evacuation to secure an operating rate is an issue. Of the vacuum pumps, the cryopump covers the widest range from high vacuum to low vacuum, and has rapidly spread to semiconductor substrate processing equipment. The cryopump is a pump that utilizes the phenomenon that the gas is condensed and solidified by lowering its temperature, and the saturated vapor pressure of the gas is lowered. FIG. 4 shows the structure of the cryopump. The cryopump 17 connected to the vacuum processing chamber 31 of the processing apparatus
The vacuum processing chamber 31 is formed by condensing the gas to be vacuum-exhausted on the surface of the cryopanel 19 having an extremely low temperature of 20 ° K or less provided therein or by adsorbing the gas to the activated carbon 20 provided in the cryopanel 19. High vacuum inside. It is essentially a sump-type pump that condenses gas, and requires regeneration work to remove the gas condensed in the pump. In the regenerating work of the cryopump, the gas accumulated in the cryopump by condensation and adsorption is released by raising the temperature of the cryopanel. Normally, as shown in the work flow of FIG. 5A, the main valve 30 between the vacuum processing chamber 31 and the cryopump 17 is
Is left closed and the cryopanel is naturally heated to release the gas, and then the roughing valve 24 is opened, and the gas in the cryopump 17 is exhausted by the roughing pump 25. Next, after closing the roughing valve 24 and checking the pressure rise, the cooling means cools down and the regeneration work is completed. When the regeneration is performed in a short time, the main valve 30 is closed and the purge valve 27 is opened as shown in FIG. 5B, and the room temperature or heated nitrogen gas is introduced into the cryopump 17 from the purge gas introduction port 26. The gas is released from the cryopanel 19 by forcibly raising the temperature under a pressure equal to or higher than the atmospheric pressure. in this case,
The excess nitrogen gas is discharged from the purge gas discharge pipe 32 because the pressure inside the pump becomes high during the introduction of nitrogen gas. After the cryopanel 19 rises to room temperature,
The purge valve 27 is closed, the roughing valve 24 is opened, and the gas in the cryopump 17 is exhausted by the roughing pump 25. After exhausting to some extent, the roughing valve 24 is closed and a pressure rise check is performed. If there is no pressure increase in the cryopump 17, the cooling means cools down.

Regarding the cryopump, Japanese Patent Publication No. 6
No. 0-55717, "LSI Process Engineering" (published by Ohmsha), page 127, "Iwanami Physics and Chemistry Dictionary 3rd edition, supplementary edition" (published by Iwanami Shoten), page 353, right column, etc.

[0004]

However, when the cryopump is left to stand and the temperature is naturally raised, it takes several hours for the cryopanel to reach the room temperature. If it is included, the playback time will be 8 hours or more. Further, when the cryopump is purged with nitrogen gas and the temperature is forcibly raised, the temperature of the cryopanel is raised above the atmospheric pressure, so even if the temperature rises, the pressure around the cryopanel is high. Therefore, it is difficult for gas molecules to be released. Therefore, also in this case, the reproduction time is not shortened so much. As described above, the cryopump takes a long time for the regenerating work, and the semiconductor substrate processing apparatus using the cryopump cannot improve its operating rate, which is a problem.

Therefore, an object of the present invention is to improve the operating rate of a semiconductor substrate processing apparatus using a cryopump by shortening the regeneration time of the cryopump.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0007]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows. That is, while introducing the temperature raising gas into the cryopump and forcibly raising the temperature of the cryopanel, the pressure inside the cryopump is changed by the exhaust means so that the saturated vapor pressure of the gas trapped in the cryopanel is It is kept at a pressure lower than the saturated vapor pressure of the lowest gas.

[0008]

According to the above means, by forcibly raising the temperature of the cryopanel, the saturated vapor pressure of the gas rises in a short time, and the atmospheric pressure in the cryopump is adsorbed and condensed on the cryopanel. Since the release of gas molecules is promoted by making it lower than the saturated vapor pressure of, the regeneration time of the cryopump can be shortened as a result.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic view of a vacuum exhaust system equipped with a cryopump used in the present invention. Reference numeral 1 denotes a cryopump for evacuating the inside of the vacuum processing chamber 12. The cryopump 1 has a cryopanel 3 for condensing gas in the vacuum chamber 2,
The back surface of the cryopanel 3 is provided with activated carbon 4 for adsorbing a gas having an extremely high saturated vapor pressure even at an extremely low temperature such as helium, hydrogen, or neon that cannot be condensed at 10 ° K to 20 ° K. There is. A cooling unit 5 is for cooling the cryopanel 3 to an extremely low temperature, for example, 10 ° K to 20 ° K. The cryopanel 3 is cooled by supplying a cooled gas, for example, helium cooled by a refrigerator (not shown) to the inside of the cooling unit 5. A roughing pump 9 for exhausting the inside of the vacuum chamber 2 is connected to the exhaust pipe 7. As the roughing pump 9, for example, a rotary pump, a dry pump, a mechanical booster pump or the like is used.
Reference numeral 10 is a pipe for introducing purge gas. The purge gas introduction pipe 10 is connected to the processing chamber exhaust pipe 13 between the main valve 14 and the cryopump 1. Accordingly, the gas suction port 6 of the cryopump 1 is used not only for sucking the gas in the vacuum processing chamber 15 but also as a purge gas introduction port. That is, the flow path of the purge gas is introduced into the cryopump 1 from the gas suction port 6 through the purge gas introduction pipe 10 and the processing chamber exhaust pipe 13. Therefore, it becomes the same as the gas flow path of the vacuum processing chamber, and the temperature of the cryopanel 3 can be efficiently raised. Further, a purge gas heater 12 for heating the purge gas before introducing it into the vacuum chamber 2 is connected to the purge gas introducing pipe 10. By introducing the purge gas heated by the purge gas heater 12 into the vacuum chamber 2, the temperature rising time of the cryopump 1 is shortened. The main valve 1 is provided between the cryopump 1 and the vacuum processing chamber 15, between the cryopump 1 and the roughing pump 9, and between the cryopump 1 and the purge gas heater 12.
4, a roughing valve 8 and a purge valve 11 are provided.

Next, a method of regenerating the cryopump 1 will be described. Regarding the regeneration timing of the cryopump 1, for example, when the temperature of the cooling unit 5 rises and exceeds 20 ° K,
When the ultimate vacuum becomes worse, the regeneration work is performed. When performing the regenerating work, the cooling means (not shown) is turned off in advance, and the work is performed according to the work flow of FIG. First, the main valve 14 is closed to disconnect the vacuum processing chamber 15 from the cryopump 1. Next, purge valve 1
1 is opened, and purge gas, for example, nitrogen gas heated by the purge gas heater 12 is introduced into the vacuum chamber 2 through the gas suction port 6. When the pressure in the vacuum chamber 2 and the temperature of the cryopanel 3 rise and become higher than the ultimate pressure of the roughing pump 9, the roughing pump 9 is operated and the roughing valve 8 is opened. By the way, the saturated vapor pressure of a gas rises with increasing temperature, and for example, most gases have
The saturated vapor pressure exceeds 1 Torr at about 150 ° K. Therefore, if the pressure is kept lower than that, the condensed gas is easily released. However, a gas having a relatively low saturated vapor pressure, such as water vapor, is
The saturated vapor pressure is 4.579 Torr at 73 ° K. In the gas condensed in the cryopump 1, if the gas having the lowest saturated vapor pressure is water vapor, when the temperature of the cryopanel 3 reaches room temperature, for example, 293 ° K, the inside of the cryopump 1 Pressure of about 17.5 Tor
If r or less is maintained, the release of water vapor is promoted like other gases. When a gas with a low saturated vapor pressure such as water vapor is contained in this way, it is effective to carry out the regeneration work while maintaining a pressure lower than the saturated vapor pressure of the gas with the lowest saturated vapor pressure. Actually, it takes a considerable time for the inside of the pump to return to room temperature, so the ultimate pressure is 10
A roughing pump having a power of about −4 Torr, in particular, a dry pump in which back diffusion of oil is relatively unlikely to occur may be used to create a state in which water vapor is easily released at a stage where the temperature in the pump is lower.

Next, in order to check the release state of the gas condensed and adsorbed in the cryopump 1, the purge valve 11 and the roughing valve 8 are closed, and the rise in pressure is checked. If no increase in pressure is observed,
The refrigerator (not shown) is turned on to cool down. When the temperature inside the pump reaches 10 ° K to 20 ° K, it becomes possible to exhaust.

Next, the function and effect of the present invention will be described.

(1) While introducing a temperature raising gas into the cryopump and forcibly raising the temperature of the cryopanel, the pressure in the cryopump is controlled by the exhaust means to obtain the pressure of the gas trapped in the cryopanel. By keeping the saturated vapor pressure of the gas lower than that of the gas with the lowest saturated vapor pressure, the saturated vapor pressure of the gas rises in a short time, and since the pressure is low, the gas condensed and adsorbed on the cryopanel Can be released in a short time.

By (2) and (1), the regeneration time of the cryopump can be drastically shortened, and the operating rate of the semiconductor substrate processing apparatus using the cryopump can be improved.

(3) In the vacuum evacuation system, the purge gas introduction pipe is connected to the processing chamber exhaust pipe between the main valve and the cryopump, and the gas suction port of the cryopump is also used as the purge gas introduction port. Therefore, the flow path of the purge gas is the same as the flow path of the gas exhausted from the vacuum processing chamber, and the temperature of the cryopanel can be efficiently raised. Therefore, the temperature rise time of the cryopanel can be shortened.

Although the invention made by the present inventor has been concretely described above based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. Although the inside of the cryopump is heated by using the heated purge gas in the above embodiment, for example, a heater may be provided on the outer circumference of the vacuum chamber of the pump to heat the inside of the cryopump.
In that case, if the heater provided on the outer periphery and the heated purge gas are used together, the temperature rising time can be further shortened. Incidentally, in the above-mentioned embodiment, the vacuum exhaust system in which the purge gas introduction pipe is connected to the processing chamber exhaust pipe was used, but the same effect can be obtained by using the cryopump regeneration method of the present invention in the conventional vacuum exhaust system. Of course, it can be obtained.

[0018]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, while introducing a temperature raising gas into the cryopump and forcibly raising the temperature of the cryopanel, the pressure in the cryopump is exhausted by the exhaust means so that the gas is saturated in the gas trapped in the cryopanel. By maintaining the pressure lower than the saturated vapor pressure of the gas with the lowest vapor pressure, the saturated vapor pressure of the gas rises in a short time, and since the pressure is low, the molecules of the gas condensed and adsorbed on the cryopanel are absorbed. Can be released in a short time, and as a result, the regeneration time of the cryopump can be dramatically shortened. Therefore, the operation rate of the semiconductor substrate processing apparatus using the cryopump can be improved.

[0020]

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic diagram of a vacuum exhaust system including a cryopump used in the present invention.

FIG. 2 is a diagram showing a work flow of a method for regenerating a cryopump according to the present invention.

FIG. 3 is a table showing the relationship between the temperature of water vapor and the saturated vapor pressure.

FIG. 4 is a diagram showing a schematic view of a vacuum exhaust system including a conventional cryopump.

FIG. 5A is a diagram showing a work flow of a method for regenerating a cryopump when the temperature is naturally raised. (B) is a diagram showing a work flow of a method for regenerating a cryopump by introducing a purge gas.

[Explanation of symbols]

1 ... cryopump, 2 ... vacuum chamber, 3 ... cryopanel, 4 ... activated carbon, 5 ... cooling part, 6 ... gas inlet, 7 ... exhaust pipe, 8 ... roughing valve, 9
...... Roughing pump, 10 ...... Purge gas introduction pipe, 1
1 ... Purge valve, 12 ... Purge gas heater, 13
...... Processing chamber exhaust pipe, 14 ...... Main valve, 15 ...... Vacuum processing chamber, 16 ...... Helium flow path, 17 ...... Cryopump, 18 ...... Vacuum chamber, 19 ...... Cryopanel, 20 ...... Activated carbon , 21 ... Cooling part, 22 ... Gas inlet, 23 ... Exhaust pipe, 24 ... Roughing valve, 2
5 ... Roughing pump, 26 ... Purge gas introduction pipe,
27 ... Purge valve, 28 ... Purge gas heater, 2
9 ... Processing chamber exhaust pipe, 30 ... Main valve, 31 ...
Vacuum processing chamber, 32 ... Purge gas discharge pipe 33 ... Helium flow path

Claims (5)

[Claims] 1. A cryopump that creates a vacuum state in a space where vacuum processing is performed by condensing or adsorbing gas on the surface of a cryogenic panel is condensed or adsorbed on the surface of the cryopanel by raising the temperature. A method of regenerating a cryopump in which the generated gas is released from the cryopanel and the gas is exhausted from the cryopump, the step of introducing a temperature raising gas into the cryopump, and the introduction of the temperature raising gas And holding the pressure in the cryopump at a pressure lower than the saturated vapor pressure of the gas having the lowest saturated vapor pressure among the gases condensed or adsorbed in the cryopanel by the exhaust means. A method for regenerating a cryopump characterized by. 2. The method for regenerating a cryopump according to claim 1, wherein the temperature raising gas is room temperature or heated nitrogen gas. 3. The exhaust means is one of a rotary pump, a dry pump and a mechanical booster pump,
Alternatively, the method for regenerating a cryopump according to claim 1 or 2, comprising a combination thereof. 4. A cryopump having a cryopanel for condensing or adsorbing gas at a cryogenic temperature, and a gas suction port provided above the cryopanel, and a cryopump connected to the gas suction port of the cryopump, A vacuum processing chamber that is evacuated by the cryopump, a processing chamber exhaust pipe that connects the cryopump and the vacuum processing chamber, and a temperature raising means for introducing a temperature raising gas into the cryopump. A vacuum exhaust system including a gas introduction pipe,
The temperature raising gas introducing pipe is connected to the processing chamber exhausting pipe, and the temperature raising gas passes from the temperature raising gas introducing pipe through the processing chamber exhausting pipe to the gas suction port to the inside of the cryopump. An evacuation system characterized by being introduced into. 5. A roughing pump is connected to the cryopump for exhausting the gas released from the cryopanel due to the temperature rise and the temperature raising gas from the inside of the cryopump. Item 4. The vacuum exhaust system according to item 4.