WO2023145385A1

WO2023145385A1 - Cryopump system and regeneration controller

Info

Publication number: WO2023145385A1
Application number: PCT/JP2022/048620
Authority: WO
Inventors: 走 ▲高▼橋
Original assignee: 住友重機械工業株式会社
Priority date: 2022-01-31
Filing date: 2022-12-28
Publication date: 2023-08-03
Also published as: TWI832665B; CN118475770A; TW202332833A

Abstract

This cryopump system comprises: a cryopump container (16); a cryopump (10) comprising a discharge valve (22) which discharges a discharge fluid from the cryopump container (16), and a discharge purge valve (24) which supplies a purge gas to the discharge valve (22) or to the downstream side thereof; and a discharge line (50) which discharges the discharge fluid from the cryopump (10) to a processing device (60), the discharge line (50) being connected to the discharge valve (22) and the discharge purge valve (24). The discharge line (50) is provided with a purge gas receiving port (52) on the processing device (60) side with respect to the discharge purge valve (24).

Description

Cryopump system and regeneration controller

The present invention relates to a cryopump system and a regeneration controller for the cryopump system.

A cryopump is a vacuum pump that traps gas molecules by condensation or adsorption in a cryopanel cooled to an extremely low temperature and exhausts it. Cryopumps are generally used to realize a clean vacuum environment required for semiconductor circuit manufacturing processes and the like. Since the cryopump is a so-called trapped-gas type vacuum pump, it requires regeneration to periodically discharge the captured gas to the outside.

JP 2012-237293 A

　Dangerous gases with various hazards such as explosive, corrosive, and toxic are sometimes used in the semiconductor manufacturing process. Hazardous gases trapped in the cryopump are discharged from the cryopump through regeneration and are rendered harmless or treated to reduce the risk in a treatment device, also called an abatement device. At this time, by supplying the purge gas to the cryopump, the dangerous gas can be diluted, the concentration of the dangerous gas flowing into the processing apparatus can be lowered, and safety can be improved.

However, immediately after the start of regeneration, due to the temperature rise of the cryopump, the stored dangerous gas can be rapidly re-vaporized and the concentration of the dangerous gas can increase significantly. Large amounts of purge gas are required to ensure that hazardous gas concentrations are kept low enough to be safe.

One exemplary objective of certain aspects of the present invention is to efficiently dilute hazardous gases exhausted from cryopumps and entering processing equipment.

According to one aspect of the invention, a cryopump system includes a plurality of cryopump vessels, each comprising a cryopump vessel, an exhaust valve for exhausting exhaust fluid from the cryopump vessel, and an exhaust purge valve for supplying a purge gas to or downstream of the exhaust valve. and a plurality of tributaries each connected to a corresponding cryopump exhaust valve and an exhaust purge valve, and a plurality of tributaries for discharging exhaust fluid from the plurality of cryopumps to the processing equipment. a discharge line comprising a junction connecting the to the processing unit.

According to one aspect of the invention, a regeneration controller for a cryopump system is provided. A cryopump system includes a plurality of cryopumps, each comprising a cryopump vessel, an exhaust valve for evacuating exhaust fluid from the cryopump vessel, and an exhaust purge valve for supplying purge gas to or downstream of the exhaust valve; A discharge line that discharges from a plurality of cryopumps to the processing equipment, and includes a plurality of branch lines each connected to a discharge valve and a discharge purge valve of the corresponding cryopump, and a confluence line that joins the plurality of branch lines to the processing equipment. and a discharge line comprising: The plurality of cryopumps includes a first cryopump and a second cryopump. The regeneration controller controls the first cryopump to discharge exhaust fluid from the first cryopump to the processing device, and controls the second cryopump to supply the purge gas from the second cryopump to the junction of the discharge line. configured to control.

According to one aspect of the invention, a cryopump system includes a cryopump comprising a cryopump vessel, an exhaust valve for exhausting exhaust fluid from the cryopump vessel, and an exhaust purge valve for supplying a purge gas at or downstream of the exhaust valve; an additional exhaust purge valve connected to the exhaust valve and the exhaust purge valve and provided in the exhaust line for exhausting the exhaust fluid from the cryopump to the processing equipment and supplying a purge gas to the exhaust purge valve to the processing equipment side.

It should be noted that arbitrary combinations of the above-described constituent elements and those in which the constituent elements and expressions of the present invention are replaced with each other between methods, devices, systems, etc. are also effective as embodiments of the present invention.

According to the present invention, it is possible to efficiently dilute the dangerous gas discharged from the cryopump and flowing into the processing equipment.

1 schematically shows a cryopump system according to an embodiment; 1 schematically shows a cryopump system according to an embodiment; FIGS. 3A to 3C are graphs showing changes in concentration of hydrogen gas in fluid discharged from the cryopump according to the embodiment. FIGS. 4A to 4C are graphs showing changes in concentration of hydrogen gas in fluid discharged from the cryopump according to the embodiment. 1 schematically shows a cryopump system according to another embodiment;

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent constituent elements, members, and processes are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience in order to facilitate explanation, and should not be construed as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

1 and 2 schematically show a cryopump system according to an embodiment. 1 schematically shows the appearance of the cryopump 10, and FIG. 2 schematically shows the internal structure of the cryopump 10. As shown in FIG. The cryopump 10 is mounted, for example, in the vacuum chamber of an ion implanter, sputtering device, vapor deposition device, or other vacuum process device to increase the degree of vacuum inside the vacuum chamber to the level required for the desired vacuum process. used. A high degree of vacuum of, for example, 10 ⁻⁵ Pa to 10 ⁻⁸ Pa is realized in the vacuum chamber.

The cryopump 10 includes a compressor 12 , a refrigerator 14 and a cryopump container 16 . The cryopump container 16 has a cryopump inlet 17 . The cryopump 10 also includes a rough valve 18 , a body purge valve 20 , an exhaust valve 22 , and an exhaust purge valve 24 , which are installed in the cryopump container 16 .

The compressor 12 is configured to recover the refrigerant gas from the refrigerator 14, pressurize the recovered refrigerant gas, and supply the refrigerant gas to the refrigerator 14 again. Refrigerator 14, also referred to as an expander or coldhead, together with compressor 12 constitutes a cryogenic refrigerator. The circulation of the refrigerant gas between the compressor 12 and the refrigerator 14 is performed with an appropriate combination of pressure and volume fluctuations of the refrigerant gas within the refrigerator 14 to form a thermodynamic cycle that produces cold. and refrigerator 14 can provide cryogenic cooling. The refrigerant gas is typically helium gas, although other suitable gases may be used. For the sake of understanding, the direction in which the refrigerant gas flows is indicated by arrows in FIG. Cryogenic refrigerators are, by way of example, two-stage Gifford-McMahon (GM) refrigerators, but may also be pulse tube refrigerators, Stirling refrigerators, or other types of cryogenic refrigerators. good too.

As shown in FIG. 2, the refrigerator 14 includes a room temperature section 26, a first cylinder 28, a first cooling stage 30, a second cylinder 32, and a second cooling stage . Refrigerator 14 is configured to cool first cooling stage 30 to a first cooling temperature and second cooling stage 34 to a second cooling temperature. The second cooling temperature is lower than the first cooling temperature. For example, the first cooling stage 30 is cooled to about 65K to 120K, preferably 80K to 100K, and the second cooling stage 34 is cooled to about 10K to 20K. First cooling stage 30 and second cooling stage 34 may also be referred to as a hot cooling stage and a cold cooling stage, respectively. By cooling the first cooling stage 30 and the second cooling stage 34 to their respective target cooling temperatures in this way, the cryopump 10 can perform the evacuation operation.

The first cylinder 28 connects the first cooling stage 30 to the room temperature section 26 so that the first cooling stage 30 is structurally supported by the room temperature section 26 . A second cylinder 32 connects a second cooling stage 34 to the first cooling stage 30 such that the second cooling stage 34 is structurally supported to the first cooling stage 30 . The first cylinder 28 and the second cylinder 32 extend coaxially along the radial direction. , are arranged in a straight line in this order.

When the refrigerator 14 is a two-stage GM refrigerator, a first displacer and a second displacer (not shown) are reciprocally arranged inside the first cylinder 28 and the second cylinder 32, respectively. . A first regenerator and a second regenerator (not shown) are incorporated in the first displacer and the second displacer, respectively. The room temperature section 26 also has a drive mechanism (not shown) such as a motor for reciprocating the first displacer and the second displacer. The drive mechanism includes a channel switching mechanism that switches the channel of the working gas so as to periodically repeat the supply and discharge of the working gas (for example, helium) to the interior of the refrigerator 14 .

The cryopump 10 also includes a radiation shield 36 and a cryopanel 38 . Radiation shield 36 is thermally coupled to first cooling stage 30 to provide a cryogenic surface for protecting cryopanel 38 from radiant heat from outside cryopump 10 or from cryopump vessel 16 . combined and cooled to a first cooling temperature.

The radiation shield 36 has, for example, a cylindrical shape and is arranged so as to surround the cryopanel 38 and the second cooling stage 34 . The end of the radiation shield 36 on the side of the cryopump inlet 17 is open so that the radiation shield 36 can receive gas entering through the cryopump inlet 17 from outside the cryopump 10 . The end of the radiation shield 36 opposite the cryopump inlet 17 may be closed or open or open. The radiation shield 36 has a gap with the cryopanel 38 and the radiation shield 36 is not in contact with the cryopanel 38 . Radiation shield 36 is also not in contact with cryopump vessel 16 .

At the cryopump inlet 17 or between the cryopump inlet 17 and the cryopanel 38, radiant heat from a heat source outside the cryopump 10 (for example, a heat source in the vacuum chamber to which the cryopump 10 is attached) is applied to the cryopanel. An inlet baffle 37 may be provided to protect 38 . Inlet baffle 37 may be secured to the open end of radiation shield 36 and thermally coupled to first cooling stage 30 of refrigerator 14 through radiation shield 36 . Alternatively, inlet baffle 37 may be attached to first cooling stage 30 . The inlet baffle 37 is cooled to the same temperature as the radiation shield 36 and is capable of condensing so-called Type 1 gases (gases that condense at relatively high temperatures, such as water vapor) on its surface.

A cryopanel 38 is thermally coupled to the second cooling stage 34 to provide a cryogenic surface for condensing Type 2 gases (e.g., gases that condense at relatively low temperatures, such as argon, nitrogen, etc.). cooled to temperature. In addition, the cryopanel 38 has at least a part of its surface (for example, the surface opposite to the cryopump inlet 17) for adsorbing Type 3 gas (for example, non-condensable gas such as hydrogen), for example, activated carbon or Other adsorbents are placed. Gas that enters the radiation shield 36 from outside the cryopump 10 through the cryopump inlet 17 is captured by the cryopanel 38 by condensation or adsorption. Various known configurations can be appropriately adopted for the arrangement and shape of the radiation shield 36 and the cryopanel 38, and thus the details thereof will not be described here.

The cryopump container 16 has a container body 16a and a refrigerator housing cylinder 16b. The cryopump vessel 16 is a vacuum vessel designed to hold a vacuum during the evacuation operation of the cryopump 10 and to withstand ambient pressure (eg, atmospheric pressure). The container body 16a has a cylindrical shape with a cryopump inlet 17 at one end and a closed other end. A radiation shield 36 is accommodated in the container body 16a, and the cryopanel 38 is accommodated in the radiation shield 36 together with the second cooling stage 34 as described above. One end of the refrigerator housing tube 16 b is coupled to the container body 16 a and the other end is fixed to the room temperature section 26 of the refrigerator 14 . The refrigerator 14 is inserted into the refrigerator housing tube 16b, and the first cylinder 28 is housed therein.

In this embodiment, the cryopump 10 is a so-called horizontal cryopump in which the refrigerator 14 is provided on the side of the container body 16a. A refrigerator insertion opening is provided in the side portion of the container body 16a, and the refrigerator housing cylinder 16b is coupled to the side portion of the container body 16a at the refrigerator insertion opening. Similarly, a hole through which the refrigerator 14 is inserted is also provided on the side of the radiation shield 36 adjacent to the refrigerator insertion opening of the container body 16a. Through these holes, the second cylinder 32 and second cooling stage 34 of the refrigerator 14 are inserted into the radiation shield 36, which is thermally coupled to the first cooling stage 30 around its side holes. It is

The cryopump can be installed in various positions at the site where it is used. As an example, the cryopump 10 can be installed in the illustrated sideways orientation, that is, with the cryopump inlet 17 facing upward. At this time, the bottom of the container body 16a is positioned below the cryopump inlet 17, and the refrigerator 14 extends horizontally.

The cryopump 10 includes a first temperature sensor 40 for measuring the temperature of the first cooling stage 30 and a second temperature sensor 42 for measuring the temperature of the second cooling stage 34 . A first temperature sensor 40 is attached to the first cooling stage 30 . A second temperature sensor 42 is attached to the second cooling stage 34 . A first temperature sensor 40 may measure the temperature of radiation shield 36 and output a first measured temperature signal indicative of the measured temperature of radiation shield 36 . A second temperature sensor 42 may measure the temperature of the cryopanel 38 and output a second measured temperature signal indicative of the measured temperature of the cryopanel 38 . A pressure sensor 44 is provided inside the cryopump container 16 . The pressure sensor 44 is installed, for example, in the refrigerator container 16b, measures the internal pressure of the cryopump container 16, and can output a measured pressure signal indicating the measured pressure.

The cryopump 10 also includes a controller 46 that controls the cryopump 10 . The controller 46 may be provided integrally with the cryopump 10 or may be configured as a control device separate from the cryopump 10 .

The controller 46 may control the refrigerator 14 based on the cooling temperature of the radiation shield 36 and/or the cryopanel 38 during the evacuation operation of the cryopump 10 . A controller 46 is connected to the first temperature sensor 40 to receive the first measured temperature signal from the first temperature sensor 40 and the second temperature sensor 42 to receive the second measured temperature signal from the second temperature sensor 42 . may be connected to

Also, the controller 46 can operate as a regeneration controller for the cryopump 10 . During regeneration operation of the cryopump 10, the controller 46 controls the refrigeration temperature based on the pressure within the cryopump vessel 16 (or based on the temperature of the cryopanel 38 and the pressure within the cryopump vessel 16, as appropriate). Machine 14, rough valve 18, body purge valve 20, exhaust valve 22, and exhaust purge valve 24 may be controlled. Controller 46 may be connected to pressure sensor 44 to receive the measured pressure signal from pressure sensor 44 .

The internal configuration of the controller 46 is realized as a hardware configuration by elements and circuits such as a computer CPU and memory, and as a software configuration is achieved by a computer program, etc., but in the figure, it is realized by linking them as appropriate. It is drawn as a function block to be It should be understood by those skilled in the art that these functional blocks can be implemented in various ways by combining hardware and software.

For example, the controller 46 can be implemented by a combination of a CPU (Central Processing Unit), a processor (hardware) such as a microcomputer, and a software program executed by the processor (hardware). The software program may be a computer program for causing the controller 46 to regenerate the cryopump 10 .

The rough valve 18 is installed in the cryopump container 16, for example, the refrigerator housing cylinder 16b. The rough valve 18 is connected to a rough pump (not shown) installed outside the cryopump 10 . The rough pump is a vacuum pump for evacuating the cryopump 10 to its operation start pressure. When the rough valve 18 is opened under the control of the controller 46, the cryopump container 16 is communicated with the rough pump, and when the rough valve 18 is closed, the cryopump container 16 is disconnected from the rough pump. The cryopump 10 can be depressurized by opening the rough valve 18 and operating the rough pump.

The body purge valve 20 is installed in the cryopump container 16, for example, the container body 16a. The body purge valve 20 is connected to a purge gas source 48 or a purge gas supply device installed outside the cryopump 10 . Purge gas is supplied from the purge gas source 48 to the cryopump vessel 16 when the body purge valve 20 is opened under the control of the controller 46, and purge gas supply to the cryopump vessel 16 is cut off when the body purge valve 20 is closed. By opening the body purge valve 20 and introducing the purge gas into the cryopump vessel 16 , the pressure of the cryopump 10 can be increased. Also, the temperature of the cryopump 10 can be raised from cryogenic to room temperature or higher.

The purge gas may be, for example, nitrogen gas, or other dry gas, and the temperature of the purge gas is adjusted, for example, to room temperature (greater than 0°C, such as 15°C to 30°C) or higher than room temperature (eg, 50°C). or 80° C. or less).

The discharge valve 22 is installed in the cryopump container 16, for example, the refrigerator housing cylinder 16b. A discharge valve 22 is provided as an outlet of the cryopump vessel 16 to discharge fluid from the inside of the cryopump 10 to the outside. The exhaust valve 22 is also the inlet to the exhaust line 50, which will be described later. Fluid is discharged from the cryopump container 16 when the discharge valve 22 is opened under the control of the controller 46, and fluid discharge from the cryopump container 16 is blocked when the discharge valve 22 is closed. The fluid discharged from the discharge valve 22 is essentially a gas, but can also be a liquid or a gas-liquid mixture. The exhaust valve 22 may be, for example, a normally closed control valve. Additionally, exhaust valve 22 may function as a vent valve or safety valve and may be configured to mechanically open when a predetermined differential pressure is applied. In that case, the discharge valve 22 is mechanically opened without requiring control when the inside of the cryopump becomes high pressure for some reason. This allows internal high pressure to escape to exhaust line 50 .

The exhaust purge valve 24 is provided to supply purge gas to the exhaust line 50 . A separate exhaust valve 22 and an exhaust purge valve 24 may be provided and the exhaust purge valve 24 may be plumbed downstream of the exhaust valve 22 . Alternatively, exhaust purge valve 24 may be provided integral with exhaust valve 22 to supply purge gas to exhaust valve 22 or downstream thereof. The exhaust purge valve 24 may be installed in the cryopump vessel 16, such as the refrigerator housing cylinder 16b. The exhaust purge valve 24 is connected to a purge gas source 48 or another purge gas source. Under the control of controller 46, purge gas is supplied from purge gas source 48 to exhaust line 50 when exhaust purge valve 24 is opened, and purge gas supply to exhaust line 50 is cut off when exhaust purge valve 24 is closed.

A discharge line 50 is provided for discharging the discharge fluid from the cryopump 10 to the processing device 60, is connected to the discharge valve 22 and the discharge purge valve 24 at its upstream end, and is connected to the processing device 60 at its downstream end.

The treatment device 60, for example, treats hazardous gases contained in the effluent (such as hydrogen gas, or other gases that are explosive, or that are corrosive or toxic) to produce harmless gases. It may be an abatement device, or it may be a treatment device that treats a hazardous gas to reduce its danger. As such a treatment device 60, a well-known abatement device or treatment device can be appropriately employed, so details thereof will not be described here.

The exhaust line 50 includes an (additional) purge gas receiving port 52 on the processing device 60 side with respect to the exhaust purge valve 24 . The purge gas receiving port 52 is at the downstream end of the exhaust line 50 and is connected to the processing device 60 . As shown, purge gas receiving port 52 may be adjacent to processing equipment 60 . Alternatively, purge gas receiving port 52 and processing device 60 may not be adjacent, and purge gas receiving port 52 may be connected to processing device 60 via other equipment included in exhaust line 50 .

An additional exhaust purge valve 54 may be connected to this purge gas receiving port 52 . An additional exhaust purge valve 54 may be connected to the purge gas source 48 or another purge gas source. The exhaust purge valve 54 may form part of the cryopump 10 and may be controlled by the controller 46 . Purge gas is supplied from the purge gas source 48 to the exhaust line 50 when the exhaust purge valve 54 is opened, and purge gas supply to the exhaust line 50 is cut off when the exhaust purge valve 54 is closed.

Thus, the exhaust purge valve 24 supplies purge gas to the exhaust line 50 upstream of the exhaust line 50 (on the exhaust valve 22 side), and the additional exhaust purge valve 54 exhausts on the downstream side of the exhaust line 50 (on the exhaust valve 22 side). Purge gas is supplied in line 50 . The body purge valve 20 enables "body purge" to supply purge gas to the container body 16a of the cryopump container 16, the discharge purge valve 24 enables "upstream purge" to supply purge gas to the upstream end of the discharge line 50, An additional exhaust purge valve 54 allows for a “downstream purge,” supplying purge gas to the downstream end of exhaust line 50 .

The flow rate of each of the body purge, upstream purge, and downstream purge may be selected, for example, from a range of 20 L/min or more to 100 L/min. The bodypurge, upstream purge, and downstream purge flow rates may be equal or different from each other. As described below, the downstream purge flow rate may be greater than the upstream purge (or body purge) flow rate.

As will be described later, the purge gas receiving port 52 may be connected to the exhaust valve 22 and the exhaust purge valve 24 of the other cryopump 10 , and the downstream purge of the exhaust line 50 is performed by supplying the purge gas from the other cryopump 10 . may be done.

The exhaust line 50 has a buffer volume 56 through which exhaust fluid from the cryopump vessel 16 flows from the exhaust valve 22 through the buffer volume 56 into the processing device 60 . Exhaust purge valve 24 supplies purge gas upstream in exhaust line 50 to buffer volume 56 and additional exhaust purge valve 54 supplies purge gas downstream in exhaust line 50 to buffer volume 56 .

Providing the discharge line 50 with the buffer volume 56 is advantageous in suppressing the concentration peak of the dangerous gas in the discharge line 50 as described later. Buffer volume 56 may be, for example, 1 L (liter) or greater, or 3 L or greater. From a space-saving point of view, the buffer volume 56 may be, for example, 30 L or less, or 10 L or less. The buffer volume 56 may be the volume of the tubing that makes up the drain line 50 , ie, the tubing that connects the drain valve 22 to the processing device 60 . Alternatively, if a large volume is desired for the buffer volume 56, the buffer volume 56 may consist of a pipe that constitutes the discharge line 50 and a buffer tank connected to this pipe. The piping may be flexible or rigid.

As the evacuation operation of the cryopump 10 continues, gas accumulates in the cryopump 10 . The cryopump 10 is regenerated in order to discharge the accumulated gas to the outside. Regeneration of the cryopump 10 generally includes heating, evacuation, and cooling down steps.

The temperature raising process includes raising the temperature of the cryopump 10 to a temperature exceeding the melting point of the dangerous gas among the gases trapped in the cryopump 10, further raising the temperature of the cryopump 10 to the regeneration temperature, including. Hazardous gases are typically, for example, type 2 or type 3 gases, and the melting point of the hazardous gas is, for example, 100K or less. The regeneration temperature is, for example, room temperature or higher. Therefore, in many cases, the dangerous gas is re-vaporized in the first half of the temperature raising process, especially immediately after the start, and is discharged from the cryopump 10 and flows into the processing device 60 . Hazardous gases are removed from the cryopump 10 during the heating process.

The heat source for raising the temperature is, for example, the refrigerator 14. The refrigerator 14 enables temperature rising operation (so-called reverse temperature rising). That is, the refrigerator 14 is configured such that adiabatic compression occurs in the working gas when the drive mechanism provided in the room temperature section 26 operates in the direction opposite to the cooling operation. The refrigerator 14 heats the first cooling stage 30 and the second cooling stage 34 with the heat of compression thus obtained. The radiation shield 36 and the cryopanel 38 are heated using the first cooling stage 30 and the second cooling stage 34 as heat sources, respectively. The purge gas supplied from the body purge valve 20 into the cryopump container 16 also contributes to the temperature rise of the cryopump 10 . Alternatively, the cryopump 10 may be provided with a heating device such as an electric heater. For example, an electric heater that is controllable independently of the operation of refrigerator 14 may be attached to first cooling stage 30 and/or second cooling stage 34 of refrigerator 14 .

In the discharge process, the gas trapped in the cryopump 10 is re-vaporized or liquefied and discharged through the discharge line 50 or through the rough valve 18 as a gas, liquid, or gas-liquid mixture. Since the type 2 gas and the type 3 gas can already be easily discharged from the cryopump 10 during the heating process, the discharge process is mainly for discharging the type 1 gas. After the discharge process is completed, the cool-down process is started. In the cooldown step, the cryopump 10 is recooled to cryogenic temperatures for evacuation operation. When the regeneration is completed in this way, the cryopump 10 can start the evacuation operation again.

By the way, one of the main uses of the cryopump 10 is to evacuate an ion implanter. In this case, hydrogen gas is stored in the cryopump 10 . The hydrogen gas trapped in the cryopanel 38 can be re-vaporized all at once during regeneration, particularly immediately after the regeneration (heating process) starts. Although the hydrogen gas is diluted in the cryopump vessel 16 by the bodypurge, the exhaust fluid flowing from the cryopump vessel 16 through the exhaust line 50 to the processing device 60 may still temporarily contain hydrogen gas in significantly higher concentrations. . Since high-concentration hydrogen gas has the risk of explosion or combustion, from the viewpoint of safety management of the cryopump 10 and the discharge line 50, it is desirable to suppress the hydrogen gas concentration peak in the discharge fluid as low as possible.

FIGS. 3(a) to 3(c) are graphs showing changes in concentration of hydrogen gas in the fluid discharged from the cryopump 10 according to the embodiment. Each figure shows the inventor's calculation of the concentration of hydrogen gas in the exhaust fluid at the purge gas receiving port 52 of the exhaust line 50, that is, in the exhaust fluid flowing into the processing device 60. FIG. In each figure, the vertical axis represents the hydrogen gas concentration (%), and the horizontal axis represents the elapsed time (minutes) from the start of regeneration.

The calculation conditions are as follows. The volume of the cryopump 10 (that is, the cryopump container 16) is assumed to be 30 L, and the initial hydrogen gas concentration in the cryopump container 16 is assumed to be 60% (corresponding to the maximum hydrogen gas storage amount of the cryopump 10). Also, the body purge flow rate (purge gas flow rate supplied from the body purge valve 20 to the cryopump container 16) is set to 20 L/min, and the upstream purge flow rate (purge gas flow rate supplied from the discharge purge valve 24 to the upstream of the discharge line 50) is set to The flow rate is 20 L/min and the downstream purge is 0 L/min (that is, no downstream purge). These conditions are common to the calculations of FIGS. 3(a) to 3(c). The size of the buffer volume 56 is different; in FIG. 3(a) the buffer volume 56 is 1 L, in FIG. 3(b) the buffer volume 56 is 3 L, and in FIG. 3(c) the buffer volume 56 is 30 L.

When the regeneration (heating process) is started, the controller 46 opens the body purge valve 20, the discharge valve 22, and the discharge purge valve 24 at the same time. At the start of regeneration, the hydrogen gas concentration at the purge gas receiving port 52 is 0% as shown. Carrying the exhaust fluid from the cryopump vessel 16 down the exhaust line 50 along with the bodypurge and upstream purge temporarily increases the hydrogen gas concentration at the purge gas receiving port 52 and reaches a peak concentration. Thereafter, as the exhaust fluid flows into the processing device 60, the hydrogen gas concentration at the purge gas receiving port 52 gradually decreases to 0% again. Such concentration change trends are common regardless of the size of the buffer volume 56, as shown in FIGS. 3(a) to 3(c).

Due to the effect of the upstream purge at the same flow rate as the body purge, the hydrogen gas concentration peak in the exhaust fluid upstream of the buffer volume 56 is estimated to be half of the initial concentration (that is, 30%). The mixing of the exhaust fluid flowing therefrom into the buffer volume 56 and the purge gas initially filling the buffer volume 56 causes the hydrogen gas concentration peak downstream of the buffer volume 56, i.e. at the purge gas receiving port 52, expected to drop somewhat further.

The effect of the buffer volume 56 can be clarified by comparing the hydrogen gas concentration peaks shown in FIGS. 3(a) to 3(c). Actually, as shown in FIG. 3(a), when the buffer volume 56 is 1 L, the hydrogen gas concentration peak is 28.0%. As shown in FIG. 3B, when the buffer volume 56 is 3 L, the hydrogen gas concentration peak is 25.6%. As shown in FIG. 3(c), when the buffer volume 56 is 30 L, the hydrogen gas concentration peak is 15.0%. Thus, the larger the buffer volume 56, the lower the peak hydrogen gas concentration in the effluent.

4(a) to 4(c) are graphs showing changes in concentration of hydrogen gas in the fluid discharged from the cryopump 10 according to the embodiment. 3(a) to 3(c), each figure shows the inventor's calculation of the hydrogen gas concentration in the exhaust fluid at the purge gas receiving port 52 of the exhaust line 50. FIG. In each figure, the vertical axis represents the hydrogen gas concentration (%), and the horizontal axis represents the elapsed time (minutes) from the start of regeneration.

The calculation conditions are as follows. The volume of the cryopump 10 (that is, the cryopump container 16) is assumed to be 30 L, and the initial concentration of hydrogen gas in the cryopump container 16 is assumed to be 60%. Also, the buffer volume 56 is assumed to be 30L. These conditions are common to the calculations of FIGS. 4(a) to 4(c). The difference is the purge flow rate. In FIG. 4(a), a flow rate of 40 L/min is added to the body purge, the body purge is 60 L/min, the upstream purge is 20 L/min, and the downstream purge is not performed. In FIG. 4(b), a flow rate of 40 L/min is added to the upstream purge, the body purge is 20 L/min, the upstream purge is 60 L/min, and the downstream purge is not performed. In FIG. 4(c), a downstream purge is performed, with a body purge of 20 L/min, an upstream purge of 20 L/min, and a downstream purge of 40 L/min.

When the regeneration (heating process) is started, the controller 46 simultaneously opens the body purge valve 20, the exhaust valve 22, the exhaust purge valve 24, and (if downstream purging is performed) the additional exhaust purge valve 54. The tendency of change in the hydrogen gas concentration at the purge gas receiving port 52 initially increases from 0%, reaches a concentration peak, and then gradually decreases to 0% again. This is common to FIGS. 4(a) to 4(c).

By comparing the hydrogen gas concentration peaks shown in FIGS. 3(c) and 4(a) to 4(c), it is possible to clarify the effect of different purge gas supply locations. As shown in FIG. 4A, when the body purge is 60 L/min, the hydrogen gas concentration peak at the purge gas receiving port 52 is 19.0%. Comparing FIG. 4(a) and FIG. 3(c), by increasing the body purge from 20 L/min to 60 L/min, the hydrogen gas concentration peak at the purge gas receiving port 52 increases from 15% to 19%. ing. This resulted in higher concentration peaks because the discharge fluid containing hydrogen gas was forced out of the cryopump vessel 16 into the discharge line 50 more rapidly as the flow rate of the body purge increased. It is considered to be a thing.

As shown in FIG. 4(b), when the upstream purge is 60 L/min, the hydrogen gas concentration peak at the purge gas receiving port 52 is 9.5%. Comparing FIG. 4(b) and FIG. 3(c), by increasing the upstream purge from 20 L/min to 60 L/min, the hydrogen gas concentration peak at the purge gas receiving port 52 is reduced from 15% to 9.5%. is decreasing. Therefore, increasing the flow rate of the upstream purge is effective in suppressing the hydrogen gas concentration peak.

As shown in FIG. 4(c), when the downstream purge is 40 L/min, the hydrogen gas concentration peak at the purge gas receiving port 52 is 7.5%. Comparing FIG. 4(c) with FIG. 3(c), by newly adding the downstream purge, the hydrogen gas concentration peak at the purge gas receiving port 52 is reduced from 15% to 7.5%. The hydrogen gas concentration peak is lower than the increase in the flow rate of the upstream purge shown in FIG. 4(b). Therefore, downstream purging is most effective in suppressing hydrogen gas concentration peaks. It is considered that supplying the purge gas at the downstream side of the exhaust line 50 (on the side of the processing device 60) as much as possible contributes to the reduction of the hydrogen gas concentration peak.

Next, focus on the flow rate ratio of body purge, upstream purge, and downstream purge. According to the inventor's study, if the cryopump volume and the buffer volume are constant, the hydrogen gas concentration peak at the purge gas receiving port 52 is determined by the flow rate ratio of the body purge, upstream purge, and downstream purge. The flow rates of the body purge, upstream purge, and downstream purge themselves affect the time required for discharge (the time from the start of regeneration until the hydrogen gas concentration becomes 0% again), but the hydrogen gas at the purge gas receiving port 52 It does not affect gas concentration peaks.

With this in mind, increasing the flow rate of the downstream purge relative to the flow rate of the body purge (or upstream purge) may reduce the amount of exhaust fluid at the purge gas receiving port 52 of the exhaust line 50, i.e., the exhaust entering the processing device 60. It is effective for suppressing the hydrogen gas concentration peak in the fluid. Also, the flow rate of the downstream purge may be made larger than the total flow rate of the body purge and the upstream purge. Also in this way, the peak of the hydrogen gas concentration in the discharged fluid flowing into the treatment device 60 can be suppressed.

As is known, hydrogen gas does not burn when the hydrogen gas concentration is 4% or less. Therefore, it is beneficial for safety to suppress the hydrogen gas concentration peak at the purge gas receiving port 52 to 4% or less.

Therefore, considering exemplary conditions under which the hydrogen gas concentration peak is 4% or less, for example, the conditions of FIG. When the flow rate of the body purge, upstream purge, and downstream purge is 1:1:11 (i.e., the downstream purge is 220 L/min), the purge gas receiving port The hydrogen gas concentration peak at 52 can be 3.9%.

By suppressing the amount of hydrogen gas stored in the cryopump 10, the hydrogen gas concentration peak during regeneration can also be suppressed. For example, under the conditions of FIG. ), the body purge, the upstream purge, and the downstream purge at a flow rate ratio of 1:1:1, the hydrogen gas concentration peak at the purge gas receiving port 52 can be 3.7%.

Also, under the conditions of FIG. When the flow rate ratio of the upstream purge and the downstream purge is 1:1:6 (that is, the downstream purge is 120 L/min), the hydrogen gas concentration peak at the purge gas receiving port 52 can be 3.8%. In this case, when the initial hydrogen gas concentration is 23%, the hydrogen gas concentration peak at the purge gas receiving port 52 is 3.8% by setting the flow rate ratio of the body purge, upstream purge, and downstream purge to 1:1:1. %.

Therefore, if the buffer volume 56 is relatively small (less than 10 L, eg, 3 L), the downstream purge flow rate may be selected from the range of 1 to 11 times the body purge (or upstream purge) flow rate. On the other hand, if the buffer volume 56 is relatively large (eg, 10 L or more and 30 L or less), the downstream purge flow rate may be selected from the range of 1 to 6 times the body purge (or upstream purge) flow rate. By doing so, it is expected that the hydrogen gas concentration peak at the purge gas receiving port 52 can be suppressed to approximately 4% or less.

As described above, according to this embodiment, since the discharge line 50 has the buffer volume 56, the dangerous gas discharged from the cryopump 10 and flowing into the processing apparatus 60 is efficiently diluted, and the concentration of the dangerous gas is reduced. peak can be suppressed. Further, according to this embodiment, by applying a downstream purge to the discharge line 50, the dangerous gas flowing into the processing device 60 can be efficiently diluted and the concentration peak of the dangerous gas can be suppressed. Purge gas consumption can be reduced compared to using only body purge (or upstream purge).

In the above description, hydrogen gas is taken as an example, but the dangerous gas is typically type 2 gas or type 3 gas, and the concentration change in the discharge line 50 is similar to that of hydrogen gas. Therefore, for other hazardous gases as well, the buffer volume 56 and the downstream purge are effective in effectively diluting the hazardous gases entering the processing system 60 and reducing the concentration peaks of the hazardous gases.

FIG. 5 schematically shows a cryopump system according to another embodiment. The cryopump system shown in FIG. 5 includes a plurality of (three in this example) cryopumps 10, unlike the cryopump systems shown in FIGS. These multiple cryopumps 10 are connected to a common processing unit 60 by an exhaust line 50 . In the following description, the

cryopumps

10a, 10b, and 10c may be used when the plurality of cryopumps 10 need to be distinguished.

Each cryopump 10 includes a rough valve 18, a body purge valve 20, an exhaust valve 22, and an exhaust purge valve 24, which are installed in the cryopump container 16 of each cryopump. The cryopump system is provided with a controller 46 that controls the plurality of cryopumps 10 , and the controller 46 is operable as a regeneration controller that controls each of the aforementioned valves of each cryopump 10 during regeneration of the plurality of cryopumps 10 . is. The configuration of the cryopump 10 shown in FIG. 5 may be similar to the cryopump 10 shown in FIGS. 1 and 2, and descriptions of similar components are omitted to avoid redundancy.

The discharge line 50 is provided to discharge the discharge fluid from the plurality of cryopumps 10 to the processing device 60 . The discharge line 50 includes a plurality of branch paths 50 a and a joint path 50 b that connects the plurality of branch paths 50 a to the processing device 60 . Each branch channel 50a is connected at its upstream end to the discharge valve 22 and the discharge purge valve of the corresponding cryopump 10, and connected at its downstream end to the combined channel 50b.

Each branch channel 50a includes a buffer volume 56 that connects the exhaust valve 22 of the corresponding cryopump 10 to the combined channel 50b. The buffer volume 56 of each tributary 50a may be in the range of 1 to 30 liters, as described above. The exhaust purge valve 24 of each cryopump 10 is connected to the branch 50 a on the upstream side (exhaust valve 22 side) with respect to the buffer volume 56 . Fluid discharged from the cryopump vessel 16 of each cryopump 10 passes from the discharge valve 22 of each cryopump 10 through the buffer volume 56 of each branch 50a of the discharge line 50 and joins in the combined flow path 50b. flow into

The body purge valve 20 of each cryopump 10 enables the body purge of the cryopump 10 . The exhaust purge valve 24 of each cryopump 10 supplies purge gas upstream of the exhaust line 50 to the buffer volume 56 to enable upstream purging of that cryopump 10 . Also, by opening the exhaust valve 22, the body purge from the body purge valve 20 can be used as an upstream purge.

The combined channel 50b of the discharge line 50 corresponds to the purge gas receiving port 52 in the above embodiment. Further, for a certain cryopump 10 (eg, the first cryopump 10a), the discharge valve 22 or the discharge purge valve 24 of another cryopump 10 (eg, the second cryopump 10b or the third cryopump 10c) is the same as the above embodiment. corresponds to an additional exhaust purge valve 54 in . Therefore, the downstream purge of a certain cryopump 10 (for example, the first cryopump 10a) causes the body purge or upstream purge of another cryopump 10 (for example, the second cryopump 10b or the third cryopump 10c) from the combined channel 50b. This is possible by receiving in the tributary 50a of a certain cryopump 10 (for example, the first cryopump 10a).

Note that the cryopump system is provided with a roughing line 58 in addition to the discharge line 50 . A roughing line 58 connects the rough valve 18 of each cryopump 10 to a common roughing pump 59 . The plurality of cryopumps 10 are roughed by roughing pumps 59 through roughing valves 18 and roughing lines 58 of each cryopump 10 .

According to this configuration, depending on the number of cryopumps 10 included in the cryopump system, it is easy to achieve a large flow rate of downstream purge. For example, the combined purge gas flow from the second cryopump 10b and the third cryopump 10c can be utilized for downstream purging of the first cryopump 10a.

However, in this case, gas flowing from another cryopump (eg, second cryopump 10b or third cryopump 10c) into a cryopump 10 (eg, first cryopump 10a) as a downstream purge is It is not desired to contain discharged hazardous gases.

Therefore, when regenerating a plurality of cryopumps 10 at the same time, the start of regeneration of a certain cryopump 10 may be prioritized over the rest of the cryopumps 10 . In other words, the start of regeneration of the remaining cryopumps 10 may be delayed with respect to the cryopump 10 that starts regeneration first. The delay time may be, for example, several minutes (eg, 2 to 10 minutes).

Therefore, the controller 46 controls one cryopump 10 to discharge the discharge fluid from one cryopump 10 to the processing device 60 and controls another cryopump 10 to supply the purge gas to the junction 50 b of the discharge line 50 . may be configured to control another cryopump 10 at the same time. Controller 46 may be configured to open body purge valve 20 of a given cryopump 10 in order to expel exhaust fluid from the given cryopump 10 to processing device 60 . Controller 46 may be configured to open exhaust purge valve 24 of another cryopump 10 to supply purge gas from another cryopump 10 to junction 50 b of exhaust line 50 .

In this way, the regeneration (heating process) of the first cryopump 10a is started first, and the discharge fluid is discharged from the first cryopump 10a to the discharge line 50 using the body purge of the first cryopump 10a. be. The exhaust purge valves 24 of the remaining second cryopump 10b and third cryopump 10c are opened, and the first cryopump 10a utilizes the purge gas from these two

cryopumps

10b, 10c as a downstream purge to the processing equipment 60. can effectively dilute the discharge fluid entering the .

After the dangerous gas is discharged from the first cryopump 10a in this way, regeneration (temperature raising process) of one of the remaining cryopumps 10 (for example, the second cryopump 10b) is started. The bodypurge and upstream purge of the first cryopump 10a can be utilized as the downstream purge for the second cryopump 10b. The upstream purge for the third cryopump 10c is still available as the downstream purge for the second cryopump 10b.

Then, after the dangerous gas is discharged from the second cryopump 10b, the regeneration (heating process) of the third cryopump 10c is started. The body purge and upstream purge of the first cryopump 10a and the second cryopump 10b can be used as the downstream purge for the third cryopump 10c.

The controller 46 may be configured to open both the body purge valve 20 and the exhaust purge valve 24 of a given cryopump 10 to exhaust the exhaust fluid from the given cryopump 10 to the processing device 60 . In this way, the exhaust fluid can be efficiently discharged from the cryopump 10 to the discharge line 50 using the body purge and the upstream purge.

The controller 46 controls the discharge purge valve of the other cryopump 10 while controlling the refrigerator 14 to cool the other cryopump 10 to prevent the formation of discharge fluid within the cryopump vessel 16 of the other cryopump 10 . 24 may be configured to open. In this way, when the regeneration (heating process) of the first cryopump 10a is started, the remaining second cryopump 10b and the third cryopump 10c can be maintained in a cooled state. Discharge from the

cryopumps

10b and 10c can be reliably blocked. In addition, the first cryopump 10a can utilize the purge gas from these two

cryopumps

10b, 10c as a downstream purge to effectively dilute the effluent flowing into the processing device 60. FIG.

The controller 46 operates the cryopump 10 and the other cryopump 10 so that the flow rate of the purge gas from the cryopump 10 to the combined channel 50b is greater than the flow rate of the purge gas from the other cryopump 10 to the combined channel 50b. may be configured to control the In this way, the flow rate of the downstream purge can be made larger than the flow rate of the body purge (or upstream purge), which is effective in suppressing the peak concentration of dangerous gases in the exhaust fluid entering the processing device 60. be.

Considering an exemplary condition in which the hydrogen gas concentration peak is 4% or less, for example, the cryopump volume is 30 L, the buffer volume 56 of each branch 50a of the discharge line 50 is 10 L, the initial hydrogen gas concentration is 60%, When the flow rates of the body purge and upstream purge of each cryopump 10 are respectively 20 L/min and 60 L/min (in this case, the downstream purge corresponds to 160 L/min), the hydrogen gas in the combined flow path 50b of the discharge line 50 is The concentration peak can be 4.0%.

Further, in this example, when the initial hydrogen gas concentration is reduced to 25%, the buffer volume 56 of each branch 50a of the discharge line 50 is reduced to 3 L, and the flow rates of the body purge and upstream purge of each cryopump 10 are reduced to Even if both are reduced to 20 L/min, the hydrogen gas concentration peak in the combined flow path 50b of the discharge line 50 can be less than 4.0%.

The present invention has been described above based on the examples. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that various design changes and modifications are possible, and that such modifications are within the scope of the present invention. By the way.

The present invention can be used in the field of cryopump systems and regeneration controllers for cryopump systems.

10 cryopump, 14 refrigerator, 16 cryopump container, 20 body purge valve, 22 exhaust valve, 24 exhaust purge valve, 46 controller, 50 exhaust line, 50a branch, 50b combined passage, 52 purge gas receiving port, 56 buffer volume, 60 processing equipment.

Claims

a plurality of cryopumps each comprising a cryopump vessel, an exhaust valve for exhausting exhaust fluid from the cryopump vessel, and an exhaust purge valve for supplying a purge gas to or downstream of the exhaust valve;
a plurality of tributaries for discharging the effluent fluid from the plurality of cryopumps to a processing device, the plurality of tributaries each connected to the discharge valve and the discharge purge valve of a corresponding cryopump; and the plurality of tributaries. and a discharge line comprising a confluence line connecting the to the processing device.
Each branch includes a buffer volume connecting the discharge valve of the corresponding cryopump to the combined channel, and the discharge purge valve of the corresponding cryopump is aligned with the buffer volume on the side of the discharge valve. 2. The cryopump system of claim 1, wherein the cryopump system is connected to a line.
The cryopump system of claim 2, wherein the buffer volume is in the range of 1 liter to 30 liters.
the plurality of cryopumps includes a first cryopump and a second cryopump;
A regeneration controller for controlling regeneration of the cryopump system, the regeneration controller controlling the first cryopump to discharge the discharged fluid from the first cryopump to the processing device, and controlling the discharge fluid from the second cryopump to the 4. The cryopump of any preceding claim, further comprising a regeneration controller configured to control the second cryopump to supply purge gas to the junction of the exhaust line. system.
the plurality of cryopumps further includes a third cryopump;
The regeneration controller controls the first cryopump to discharge the discharge fluid from the first cryopump to the processing device, and discharges the purge gas from the second cryopump and the third cryopump. 5. The cryopump system of claim 4, configured to control the second cryopump and the third cryopump to supply the combined path of a line.
each of the plurality of cryopumps includes a body purge valve that supplies purge gas to the cryopump vessel;
The regeneration controller is configured to open both the body purge valve and the exhaust purge valve of the first cryopump to exhaust the exhaust fluid from the first cryopump to the processing device. 6. The cryopump system according to claim 4 or 5.
each of the plurality of cryopumps includes a refrigerator that cools the cryopump;
The regeneration controller controls the refrigerator to cool the second cryopump to prevent formation of the exhaust fluid within the cryopump vessel of the second cryopump while controlling the refrigerator to cool the second cryopump. 7. The cryopump system of any of claims 4-6, wherein the exhaust purge valve is configured to open.
The regeneration controller increases the flow rate of the purge gas from the second cryopump to the combined channel compared to the flow rate of the purge gas from the first cryopump to the combined channel. 8. The cryopump system of any of claims 4-7, configured to control the second cryopump.
A regeneration controller for a cryopump system, comprising:
The cryopump system includes:
a plurality of cryopumps each comprising a cryopump vessel, an exhaust valve for exhausting exhaust fluid from the cryopump vessel, and an exhaust purge valve for supplying a purge gas to or downstream of the exhaust valve;
a plurality of tributaries for discharging the effluent fluid from the plurality of cryopumps to a processing device, the plurality of tributaries each connected to the discharge valve and the discharge purge valve of a corresponding cryopump; and the plurality of tributaries. and a discharge line comprising a confluence path for joining the processing equipment,
the plurality of cryopumps includes a first cryopump and a second cryopump;
The regeneration controller controls the first cryopump to discharge the discharge fluid from the first cryopump to the processing device, and directs the purge gas from the second cryopump to the junction of the discharge line. A regeneration controller configured to control the second cryopump to supply.
a cryopump comprising a cryopump container, a discharge valve for discharging discharged fluid from the cryopump container, and a discharge purge valve for supplying a purge gas to the discharge valve or its downstream;
an additional discharge purge valve connected to the discharge valve and the discharge purge valve, provided in a discharge line for discharging the discharge fluid from the cryopump to the processing device, and supplying a purge gas to the processing device side with respect to the discharge purge valve; A cryopump system comprising:
11. The cryopump system of claim 10, wherein the exhaust line comprises a buffer volume connected between the exhaust purge valve and the additional exhaust purge valve.