KR102580537B1 - Method for regenerating cryogenic pump - Google Patents

Abstract

A refrigerator having a first stage unit and a second stage unit, and cooling the first stage unit and the second stage unit using a high pressure refrigerant; A cryo panel including a first-stage panel cooled by the first-stage stage unit and a second-stage panel cooled by the second stage unit; a cryopump vessel surrounding the cryopanel and including a radiation shield surrounding the first stage unit; A first heater installed in the first stage panel; And a method of regenerating a cryopump including a second heater installed in the second stage panel includes a temperature raising process step of turning on the first heater to increase the temperature of the radiation shield and the first stage panel, the cryo A roughing process step in which a roughing valve is controlled to control the vacuum in the cryopump vessel while the pump vessel is maintained at a pressure that allows solid ice to sublimate into gaseous vapor, purging gas into the cryopump vessel. It includes a purge process step of supplying and a cool-down process step of lowering the temperature of the first-stage panel and the second-stage panel.

Description

{METHOD FOR REGENERATING CRYOGENIC PUMP}

The present invention relates to a method for regenerating a cryopump.

Cryogenic cooling is widely used in many industrial fields, such as semiconductor manufacturing and testing fields. Here, ultra-low temperature may mean a temperature of -200 degrees or lower, and the cooling process to obtain ultra-low temperature typically includes a compressor, condenser, expander, and evaporator, and the refrigerant is evaporated in the evaporator to create an ultra-low temperature environment. .

In relation to technology for creating such an ultra-low temperature environment, Korean Patent Publication No. 2020-0079062, a prior art, discloses an ultra-low temperature freezer.

To create an ultra-low temperature environment, a GM (Gifford McMahon) refrigerator, a high vacuum cryopump refrigerator, is mainly used. The cryopump is a collection pump, and it is difficult to pump beyond a certain capacity, so after it is used in the cooling process, a regeneration process must be performed periodically.

The regeneration process refers to a process that restores pumping ability by desorbing and evaporating moisture and gases that have been adsorbed, condensed, and solidified on the cryopump's cryopanel. The regeneration process performed in a conventional cryopump will be briefly described with reference to FIG. 1.

Figure 1 is a diagram showing a regeneration process performed in a conventional cryopump. Referring to FIG. 1, the regeneration process of the cryopump generally includes a warm-up (110) process, a purge (120) process, a roughing (130) process, and a cool-down (140) process. It is composed. As the cryopump performs the regeneration process, the temperature 100 of the first stage part and the temperature 101 of the second stage part change, and as the above-described processes are sequentially performed, the regeneration process is completed (150).

In general, an 8-inch sputtering facility used in the production of semiconductor foundry products is equipped with 6 chambers (4 process chambers, 1 transfer chamber, and 1 buffer chamber), and one cryopump is installed in each chamber. do. The production process performed in these sputter facilities repeats the photo process, etching process, ion implantation process, and deposition process, thereby creating numerous semiconductor circuits on the wafer.

Here, the sputtering equipment produces wafers at a high speed through the wet scrubber process, which separates or collects fine particles in the dusty gas by liquid crystals, liquid films, and bubbles generated by dispersing the cleaning liquid or dusty gas in the etching process. While rotating, water is sprayed on the surface of the wafer to clean it, and at the same time, it is rotated at high speed and dried using centrifugal force.

Afterwards, a metal process is carried out to connect metal wires according to the semiconductor circuit pattern, but when the buffer chamber of the sputtering facility has an atmosphere of 300 degrees, much of the water remaining from the previous process evaporates, forming a cold head. It accumulates on the cold head and forms ice. Here, when the regeneration process proceeds, ice accumulates on the bottom between the can and the pump body, and ROR (Rate of Rise, leakage test) occurs due to the generation of H ₂ O inside the cryopump. ) A problem is occurring that a long playback time of about 8 hours or more is required, causing a failure.

The reason for the generation of such H ₂ O is that it is collected in an ice state on the cryo stage before entering the buffer chamber, and when the regeneration process proceeds, the state changes to water as the surrounding temperature and pressure increase in the purge process, causing cryo Oh, it accumulates inside the chamber. Afterwards, as the pump progresses, it is vaporized as the chamber pressure decreases, creating a deteriorated pressure condition and causing ROR failure, which causes the regeneration time to become longer.

The first heater is turned on to raise the temperature of the radiation shield and the first stage panel, and the vacuum in the cryopump container is maintained at a pressure that allows solid ice to sublimate into gaseous vapor. The purpose is to provide a method of regenerating a cryopump that controls a roughing valve to regulate .

An object is to provide a cryopump regeneration method that supplies purge gas into the cryopump container and lowers the temperature of the first-stage panel and the second-stage panel.

However, the technical challenges that this embodiment aims to achieve are not limited to the technical challenges described above, and other technical challenges may exist.

As a means for achieving the above-described technical problem, an embodiment of the present invention includes a first stage unit and a second stage unit, and cooling the first stage unit and the second stage unit using a high-pressure refrigerant. freezer; A cryo panel including a first-stage panel cooled by the first-stage stage unit and a second-stage panel cooled by the second stage unit; a cryopump vessel surrounding the cryopanel and including a radiation shield surrounding the first stage unit; A first heater installed in the first stage panel; and a method of regenerating a cryopump including a second heater installed in the second-stage panel, the temperature increasing process step of turning on the first heater to increase the temperature of the radiation shield and the first-stage panel; A roughing process step of controlling a roughing valve to adjust the vacuum in the cryopump vessel while maintaining the cryopump vessel at a pressure that allows solid ice to sublimate into gaseous vapor, into the cryopump vessel. A method of regenerating a cryopump can be provided, including a purge process step of supplying a purge gas and a cool-down process step of lowering the temperature of the first-stage panel and the second-stage panel.

According to one embodiment, before the temperature increasing process step, the step of stopping operation of the refrigerator may be further included.

According to one embodiment, the pressure at which the solid ice can sublimate into gaseous vapor is inside It can be torr.

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According to one embodiment, the purge process step includes maintaining the temperature of the first-stage panel at a set temperature using the first heater and maintaining the temperature of the second-stage panel to the set temperature using the second heater. It may include a maintenance step.

The above-described means for solving the problem are merely illustrative and should not be construed as limiting the present invention. In addition to the exemplary embodiments described above, there may be additional embodiments described in the drawings and detailed description of the invention.

According to one of the above-described means for solving the problems of the present invention, the first heater is turned on to increase the temperature of the radiation shield and the first stage panel, thereby directly sublimating solid ice into gaseous vapor. A cryopump can be provided.

The temperature and pressure inside the cryopump are controlled by controlling the roughing valve to control the vacuum in the cryopump container while the cryopump container is maintained at a pressure that allows solid ice to sublimate into gaseous vapor. Technology can provide cryopumps that can maintain an environment that maintains a sublimation zone from solid to gas during the change of state of water.

By eliminating the cause of liquid H ₂ O accumulating on the bottom of the radiation shield and the first-stage panel, a cryopump can be provided that can shorten the regeneration time required by the cryopump.

Figure 1 is a diagram showing a regeneration process performed in a conventional cryopump.
Figure 2 is an exemplary diagram showing a cryopump according to an embodiment of the present invention.
Figure 3 is a flowchart of a regeneration method performed in a cryopump according to an embodiment of the present invention.
Figure 4 is an exemplary diagram showing the pressure at which ice in a solid state can be sublimated into vapor in a gaseous state according to an embodiment of the present invention.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only the case where it is "directly connected," but also the case where it is "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, this does not mean excluding other components unless specifically stated to the contrary, but may further include other components, and one or more other features. It should be understood that it does not exclude in advance the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In this specification, 'part' includes a unit realized by hardware, a unit realized by software, and a unit realized using both. Additionally, one unit may be realized using two or more pieces of hardware, and two or more units may be realized using one piece of hardware.

In this specification, some of the operations or functions described as being performed by a terminal or device may instead be performed on a server connected to the terminal or device. Likewise, some of the operations or functions described as being performed by the server may also be performed on a terminal or device connected to the server.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings.

Figure 2 is an exemplary diagram showing a cryopump according to an embodiment of the present invention. Referring to FIG. 2, the cryopump 200 includes a refrigerator 210, a first stage unit 211, a second stage unit 212, a first stage panel 220, a second stage panel 221, and a cryo pump 200. It may include a pump container 230, a radiation shield 231, a first heater 240, a second heater 241, and a roughing valve 250. The cryopump 200 according to an embodiment of the present invention may be a GM (Gifford-McMahon) refrigerator equipped with a first stage unit 211 and a second stage unit 212.

The refrigerator 210 may be provided with a first-stage stage unit 211 and a second-stage stage unit 212 that is cooled to a lower temperature than the first stage unit 211. Here, the first stage unit 211 and the second stage unit 212 can create a cryogenic environment using a cooling principle that allows the displacer to reciprocate within the cylinder and expand the He gas inside.

The cryopump vessel 230 may surround the cryopanel. Here, the cryo panel may include a first-stage panel 220 and a second-stage panel 221. The first-stage panel 220 includes a first-stage array and a baffle, and the first-stage array is directly cooled by the first stage unit 211, and the baffle is indirectly cooled by the first stage unit 211, The two-stage panel 221 includes a two-stage array and can be cooled by the two-stage stage unit 212. Hereinafter, the description will be made assuming that the first-stage panel 220 is a baffle.

The cryopump vessel 230 may include a radiation shield 231. The radiation shield 231 can protect the cryopump 200 from radiant heat at room temperature by surrounding the first stage unit 211.

The first heater 240 is installed in the first stage unit 211 and can increase the temperature of the first stage unit 211.

The second heater 241 is installed in the second stage part 212 and can increase the temperature of the second stage part 212.

The roughing valve 250 can control the vacuum in the cryopump container 230.

Figure 3 is a flowchart of a regeneration method performed in a cryopump according to an embodiment of the present invention. The regeneration method of the cryopump 200 shown in FIG. 3 includes steps processed in time series according to the embodiment shown in FIG. 2 . Therefore, even if the content is omitted below, it also applies to the regeneration method of the cryopump 200 performed in the cryopump 200 according to the embodiment shown in FIG. 2.

In step S310, the cryopump 200 may turn on the first heater 240 to increase the temperature of the radiation shield 231 and the first stage panel 220. Here, before performing step S310, the cryopump 200 may further include stopping the operation of the refrigerator 210.

In step S320, the cryopump 200 performs roughing to control the vacuum in the cryopump container 230 while maintaining the cryopump container 230 at a pressure that allows solid ice to sublimate into gaseous vapor. The valve 250 can be controlled. Here, the pressure at which solid ice can sublimate into gaseous vapor is inside It can be torr.

The cryopump 200 opens the roughing valve 250 when the pressure in the cryopump container 230 is higher than the pressure at which solid ice can sublimate into gaseous vapor, and the roughing valve 250 opens. After this, when the temperature of the first stage panel 220 reaches a preset temperature, a step of closing the roughing valve 250 may be included. Here, the preset temperature may be 250K to 300K. The pressure at which solid ice can sublimate into gaseous vapor will be briefly explained with reference to FIG. 4.

Figure 4 is an exemplary diagram showing the pressure at which ice in a solid state can be sublimated into vapor in a gaseous state according to an embodiment of the present invention. Referring to FIG. 4, in the water phase diagram graph 400, the state of water can be expressed as x-axis: temperature (410) and y-axis: pressure (420).

Referring to FIG. 4, it may be in a solid state (ice) when the temperature is from -20 degrees to 0 degrees and the pressure is from 10 ^-3 to 10 ³ torr, and the temperature is from 0 degrees to 120 degrees, and the pressure is from 10 -2 to 10 ^-2 torr. It may be in a liquid state (water) at 10 ³ torr, the temperature is from -20 degrees to 120 degrees, and it may be in a gaseous state (steam) at 10 ^-3 to 10 torr.

Here, the pressure at which solid ice can sublimate into gaseous vapor is the intersection of the solid state line and the gaseous line. inside It could be torr(430).

That is, the present invention When carrying out the regeneration process while maintaining the pressure below, moisture can be easily removed by directly sublimating it without going through the liquid state at a temperature below 0 degrees.

In addition, by controlling the internal temperature and pressure of the cryopump 200, an environment is maintained in which a region that directly sublimates from the solid state to the gas state is maintained during the state change process of water, so that the liquid H ₂ O Playback time can be reduced by removing the causative factors.

Returning to FIG. 3 , the cryopump 200 may supply purge gas into the cryopump container 230 in step S330. Here, the purge gas may be nitrogen (N ₂ ) gas.

In step S330, the cryopump 200 maintains the temperature of the first stage panel 220 at the set temperature using the first heater 240 and the second stage panel 221 using the second heater 241. It may include maintaining the temperature at the set temperature.

In step S340, the cryopump 200 may lower the temperature of the first-stage panel 220 and the second-stage panel 221.

According to the present invention, even if the cryopump 200 is used in a sputtering facility, the regeneration speed can be improved by minimizing the generation of water in the regeneration process.

In the above description, steps S310 to S340 may be further divided into additional steps or combined into fewer steps, depending on the implementation of the present invention. Additionally, some steps may be omitted or the order between steps may be switched as needed.

The cryopump regeneration method performed in the cryopump described through FIGS. 2 to 4 may also be implemented in the form of a computer program stored on a medium executed by a computer or a recording medium containing instructions executable by a computer. You can. Additionally, the cryopump regeneration method performed in the cryopump described with reference to FIGS. 2 to 4 may also be implemented in the form of a computer program stored in a medium executed by a computer.

Computer-readable media can be any available media that can be accessed by a computer and includes both volatile and non-volatile media, removable and non-removable media. Additionally, computer-readable media may include computer storage media. Computer storage media includes both volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

200: Cryo pump
210: Freezer
211: 1st stage part
212: 2nd stage part
220: 1st stage panel
221: two-stage panel
230: Cryo pump container
231: Copy Shield
240: first heater
241: second heater
250: Roughing valve

Claims (7)

A refrigerator having a first stage unit and a second stage unit, and cooling the first stage unit and the second stage unit using a high pressure refrigerant; A cryo panel including a first stage panel cooled by the first stage unit and a second stage panel cooled by the second stage unit; a cryopump vessel surrounding the cryopanel and including a radiation shield surrounding the first stage unit; A first heater installed in the first stage panel; And a method for regenerating a cryopump including a second heater installed in the two-stage panel,
A temperature increasing process step of turning on the first heater to increase the temperature of the radiation shield and the first stage panel;
A roughing process step of controlling a roughing valve to adjust the vacuum in the cryopump container while maintaining the cryopump container at a pressure that allows solid ice to sublimate into gaseous vapor;
A purge process step of supplying a purge gas into the cryopump container; and
Cool-down process step of lowering the temperature of the first-stage panel and the second-stage panel
A method of regenerating a cryopump, comprising:
According to claim 1,
Before the temperature raising process step,
A method of regenerating a cryopump, further comprising stopping operation of the refrigerator.
According to claim 1,
The pressure at which the solid ice can sublimate into gaseous vapor is inside A method of regenerating a cryopump, which is torr.
delete delete delete According to claim 1,
The purge process step is,
maintaining the temperature of the first stage panel at a set temperature using the first heater; and
A method of regenerating a cryopump comprising maintaining the temperature of the two-stage panel at a set temperature using the second heater.

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