JPH0868380A - Regeneration method for cryopump - Google Patents

Abstract

PURPOSE: To rapidly increase the temperature of a cold head to a room temperature by increasing the respective temperatures of cold heads and gasifying condensed and adsorbed gas, and discharging the gasified gas together with regenerated gas fed in a vacuum chamber. CONSTITUTION: A first stage cold head 5 provided at a tip part with a radiation shield 4 and a second stage cold head 7 at a tip part with a cold panel 6 are arranged in a vacuum chamber 3 having an openable gate valve 2 located at one end of a cryopump 1. A heating means 14 is installed at the radiation shield 4 and a heating means 15 at the cold panel 6 in such a manner to surround the body parts of the cold heads 5 and 7. The temperatures of the cold heads 5 and 7 are increased, and condensed and adsorbed gas is gasified. The gasified gas is discharged through an exhaust pipe 24 together with regenerated gas in the vacuum chamber 3. Thus, a regeneration work is rapidly conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryopump, and more particularly, to a gas exhausting function of a cryopump by evaporating and condensing gas condensed and adsorbed on a panel portion of a cold head cooled to an extremely low temperature when required. Is about how to play.

[0002]

2. Description of the Related Art A cryopump is a type of vacuum pump that exhausts gas by condensing or solidifying gas on a panel surface cooled to an extremely low temperature or adsorbing it on a gas adsorption surface on which activated carbon is placed. It is used by being incorporated in a manufacturing device, and its structure and function are described in JP-A-63-
It is disclosed in Japanese Patent No. 183279.

The gas exhausting power of the cryopump decreases with an increase in the amount of gas condensed, solidified and adsorbed (hereinafter referred to as condensed) on the panel surface or the like.

For this reason, it is necessary to periodically perform a cryopump regeneration operation, that is, to remove the gas condensed on the panel surface, which is disclosed in Japanese Utility Model Application Laid-Open No. 57-61188 (hereinafter referred to as prior art 1). No. 117689 (hereinafter, referred to as Prior Art 2) makes a concrete proposal of regenerating by electrothermal heating.

That is, the cryopump 1 of the prior art 1
The heating means 14 is installed in the portion of the first-stage cold head 5 on the high temperature side as shown in FIG. 4. In the cryopump having such a configuration, the controller 18 is operated to heat the heating means. When the heating by 14 is stopped,
The baffle 4a connected to the radiation shield 4 of the first stage cold head 5 and the cold panel 6 of the second stage cold head 7 are circulated by a cooling medium (for example, helium gas) that is circulated from the cooling unit 9 into the cylinders 10 and 11. It can be cooled to cryogenic temperatures to condense gas on these cooled panel surfaces.

When a large amount of gas is condensed on the panel and the ability to exhaust the gas decreases, the controller 18 heats the heating means 14 to a predetermined temperature to vaporize the liquid and the like remaining in the vacuum chamber 3. While the valve 21.2
2 is opened and, for example, a dry nitrogen gas is supplied as a regeneration gas into the vacuum chamber from the regeneration gas supply pipe 23, and the gas vaporized in the chamber is discharged from the exhaust pipe 24 together with the regeneration gas, whereby the cryopump We are trying to reproduce.

On the other hand, the cryopump 1 of the prior art 2 is
As shown in FIG. 5, the cold panel 6 of the second-stage cold head 7 on the low temperature side is provided with the heating means 15, and the heating means 15 moves the cold panel 6 from other parts in the vacuum chamber 3. It is said that the low volatile gas sublimated from the cold panel 6 and the first-stage cold head 5 at the time of regeneration is prevented from being re-adsorbed by the adsorption panel by reaching the predetermined temperature even faster.

Whether the first stage cold head 5 on the high temperature side is heated or the second stage cold head 7 on the low temperature side is heated depends on the type of gas to be discharged. For example, water with a relatively high condensation / solidification temperature is condensed and solidified on the panel of the first-stage cold head, so the first-stage cold head is heated and the condensation temperature of argon, hydrogen, etc. is relatively low. Since the gas condenses on the panel of the second-stage cold head, in this case, the device for heating the second-stage cold head is devised.

[0009]

However, in order to completely regenerate the gas discharge capacity of the cryopump, it is necessary to raise both the first and second cold heads to about room temperature. 6 ・ As illustrated in Fig. 7,
It takes time for the temperature rise of the second stage cold head in the cryopump where the heating means is installed in the first stage cold head, and the temperature rise of the first stage cold head occurs in the cryopump where the heating means is installed in the second stage cold head. However, there is a problem that it takes time to solve the problem.

[0010]

As a concrete means for solving the above-mentioned problems of the prior art, the present invention condenses a gas into a plurality of cryogenic cold heads having different cooling temperature levels installed in a vacuum chamber.・ In a cryopump that removes by adsorption, etc., the communication between the vacuum chamber and the chamber to be evacuated is cut off, and the heating means installed in each cold head gives different amounts of heat to raise the temperature of each cold head, A method for regenerating a cryopump that vaporizes the condensed and adsorbed gas in each and discharges the vaporized gas together with the regenerated gas supplied into the vacuum chamber,

In a cryopump for removing gas by condensing and adsorbing gas to a plurality of cryogenic cold heads having different cooling temperature levels and heat capacities installed in the vacuum chamber, the communication between the vacuum chamber and the exhaust chamber is cut off. Then, the amount of heat based on the difference between the cooling temperature of the cold head and the heat capacity is given by the heating means installed in each cold head to increase the temperature of each cold head, and the temperature difference of the cold head is controlled to a predetermined value or less, A method for regenerating a cryopump that vaporizes the condensed and adsorbed gas in each cold head and discharges the vaporized gas together with the regenerated gas supplied into the vacuum chamber, thereby solving the above-mentioned problems of the conventional technology. It is a solution.

[0012]

Since the first-stage cold head and the second-stage cold head are respectively heated based on the difference in cooling temperature and heat capacity, both cold heads can be quickly and simultaneously heated to room temperature. . Therefore, the first
The gas condensed in the first cold head and the second cold head is quickly vaporized and discharged together with the regenerated gas.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for regenerating a cryopump 1 according to the present invention will be described in detail below with reference to FIGS. In addition,
In FIG. 1, portions indicated by the same reference numerals as those in FIGS. 4 and 5 are portions that perform the same functions as the portions described with reference to these drawings.

The structure and function of the cryopump 1 itself is well known in the art. Inside the vacuum chamber 3 having a gate valve 2 which can be opened and closed at one end, a radiation shield 4 also called a radiation shield panel is provided at the tip. A first-stage cold head 5 and a second-stage cold head 7 having a cold panel 6, which is also called a cryopanel, at its tip end are connected to the exhaust chamber 8 via the gate valve 2 to cool the cooling unit 9. By the action, the radiation shield 4 and the baffle 4a connected to the radiation shield 4 are cooled to, for example, 50K, the cold panel 6 is cooled to, for example, 10K, and the condensation temperature is relatively high in the high temperature side radiation shield 4 and the baffle 4a. For example, by condensing and solidifying water, hydrocarbons, etc., Such as to condense the low argon or hydrogen gas with condensation temperature in Rudopaneru 6, in order to increase the vacuum degree of the exhaust chamber 8.

It should be noted that the radiation shield 4, the baffle 4a, and the cold panel 6 are quickly cooled to a predetermined temperature by the cryogenic helium gas which is circulated and supplied from the cooling unit 9 into the cylinders 10 and 11.
A cold head body 12, 13 which is arranged at the tip of the cylinders 10 and 11 and which fixes the radiation shield 4 and the cold panel 6, and the radiation shield 4, the baffle 4a, and the cold panel 6 have good thermal conductivity. It is formed by.

On the other hand, the cylinder 10 is made of a thin stainless steel plate and constitutes a displacer having mesh copper inside, and the cylinder 11 is also a displacer having granular lead inside the thin stainless steel plate. There is. Therefore, the first-stage cold head 5 and the second-stage cold head 7 are substantially in a heat insulating state.

In the cryopump 1 having the above structure, when the amount of gas condensed on the radiation shield 4, the baffle 4a, and the cold panel 6 increases as described above, the heat transfer efficiency on these surfaces decreases and the cooling action is impaired. Since it becomes impossible to condense the required gas, the heating means 14 is provided on the radiation shield 4 of the first-stage cold head 5, the heating means 15 is provided on the cold panel 6 of the second-stage cold head 7, and the respective cold head bodies are provided. Radiation shield 4 as well as the surrounding part
・ Radiation shield 4 ・ Cold panel 6 by installing temperature sensors 16 and 17 in the respective cold panels 6 at positions separated by appropriate distances from the heating means 14 and 15.
Of the first stage cold head 5 (including the baffle 4a) and the second stage cold head 7 that are configured to be able to separately measure the temperature of the first stage, and are measured and output by the temperature sensors 16 and 17 during cooling. Heating means 14 based on the heat capacity of
・ 15 Controllers for the amount of heat generated per unit time
Are configured to be controlled.

That is, the controller 18 is composed of a microcomputer having necessary functions such as storage, calculation and comparison, and the radiation shield 4, the baffle 4a and the second stage cold head 7 of the first stage cold head 5 are included. The cold panel 6 has a predetermined cryogenic temperature, for example 50K and 10
From the state of being cooled to K, for example, an energizing amount that raises both to 300 K by energizing for 20 minutes is set to the heating means 14.1.
In consideration of the heat capacities of both cold heads for each of the five, specifically, they are experimentally obtained and stored.

Therefore, for example, when the degree of vacuum in the exhausted chamber 8 measured by the vacuum gauge 19 does not reach a predetermined degree of vacuum, the operation of the cryopump 1 is stopped automatically or manually, and the gate valve 2 is automatically or manually operated. To shut off the communication between the inside of the vacuum chamber 3 and the chamber 8 to be evacuated, and the temperature sensors 16 and 17 close the radiation shield 4
-Measure the temperature of each cold panel 6.

After confirming that the temperature of the radiation shield 4 and the temperature of the cold panel 6 are 50 K and 10 K, respectively, the electric current stored in the controller 18 is applied to the heating means 1.
Since the heat generation amount is individually controlled by flowing into each of 4 and 15, the temperature of the radiation shield 4 and the cold panel 6 reaches 300K at the same time 20 minutes after the start of regeneration, as shown in FIG.

When regeneration is started, the temperatures of the radiation shield 4, the baffle 4a and the cold panel 6 rise, and the adsorbed gas is released from the panel. Vacuum chamber 3
When the internal pressure gradually rises and reaches atmospheric pressure, the valves 21 and 22 are opened, and, for example, dry nitrogen gas is supplied as a regeneration gas from the regeneration gas supply pipe 23.

By the above-mentioned operation, the temperature inside the vacuum chamber 3 is raised to a temperature at which the residual liquid or the like is vaporized by the heat generated by the heating means 14 and 15, so that the radiation shield 4 and the baffle 4a are condensed and solidified and attached. Since the water and hydrocarbons that had been stored and the argon gas and hydrogen gas that had condensed and adhered to the cold panel 6 were all vaporized, these gases were quickly discharged to the outside through the exhaust pipe 24 together with the regenerated gas, The pump 1 is regenerated in a reusable state.

The same current as the current flowing through the heating means 15 installed in the second-stage cold head 7 having a small heat capacity is
When flowing through the heating means 14 installed in the first-stage cold head 5 having a large heat capacity, the radiation shield 4 reaches a predetermined temperature of 300K as shown in FIG. 3, but much more than the cold panel 6 reaches a predetermined 300K. It takes a long time.

By the way, since the present invention is not limited to the above-mentioned embodiments, various modifications can be made without departing from the scope of the claims.

For example, when one or both of the radiation shield 4 and the cold panel 6 at the start of reproduction is out of a predetermined temperature, for example, to realize the relationship between the elapsed reproduction time and the temperature as shown in FIG. When the temperature measured by the temperature sensors 16 and 17 is lower than the stored current value, a large amount of current is applied, and when the measured temperature is high, a small amount of current is applied, so that the heating means 1 converges on the control curve of FIG.
The current value flowing in 4 ・ 15 is controlled appropriately, and the temperature of the radiation shield 4 and the cold panel 6 are both set to 3 after 20 minutes.
You may control so that it may heat up to 00K.

[0026]

As described above, in a cryopump for removing gas by condensing and adsorbing gas to a plurality of cryogenic cold heads having different cooling temperature levels installed in the vacuum chamber, the inside of the vacuum chamber and the exhausted gas are exhausted. The communication with the chamber is cut off, the heating means installed in each cold head gives different amounts of heat to raise the temperature of each cold head, vaporize the condensed and adsorbed gas in each cold head, and the vaporized gas It is a method of regenerating a cryopump that discharges together with the regenerating gas supplied into the vacuum chamber.

In a cryopump for removing gas by condensing and adsorbing gas to a plurality of cryogenic cold heads having different cooling temperature levels and heat capacities installed in the vacuum chamber, the communication between the vacuum chamber and the exhausted chamber is cut off. Then, the amount of heat based on the difference between the cooling temperature and the heat capacity of the cold head is applied by the heating means installed in each cold head to increase the temperature of each cold head, and the temperature difference of the cold head is controlled to be equal to or less than a predetermined value 3. Because it is a cryopump regeneration method that vaporizes the condensed / adsorbed gas in each cold head and discharges this vaporized gas together with the regenerated gas supplied into the vacuum chamber.

In any of the above-mentioned regeneration methods, the temperatures of the first-stage cold head and the second-stage cold head are simultaneously raised to room temperature, and the gas condensed in the cold head is vaporized to promptly regenerate with the regeneration gas. Therefore, the recycling work can be performed quickly, and the operating rate of the device can be greatly increased.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a cryopump.

FIG. 2 is an explanatory diagram showing a reproducing method.

FIG. 3 is an explanatory diagram showing a comparative example.

FIG. 4 is an explanatory diagram of a device according to the related art 1.

FIG. 5 is an explanatory diagram of a device of Prior Art 2.

FIG. 6 is an explanatory diagram of reproduction according to the related art 1.

FIG. 7 is an explanatory diagram of reproduction according to the related art 2.

[Explanation of symbols]

 1 Cryopump 2 Gate Valve 3 Vacuum Chamber 4 Radiation Shield 4a Baffle 5 First Stage Cold Head 6 Cold Panel 7 Second Stage Cold Head 8 Exhaust Chamber 9 Cooling Unit 10/11 Cylinder 12/13 Cold Head Main Body 14/15 Heating means 16/17 Temperature sensor 18 Controller 19 Vacuum gauge 21/22 Valve 23 Regeneration gas supply pipe 24 Exhaust pipe A Temperature rise curve of the first cold head B Temperature rise curve of the second cold head

Claims (2)

[Claims] 1. In a cryopump for removing gas by condensing and adsorbing gas to a plurality of cryogenic cold heads having different cooling temperature levels installed in the vacuum chamber, the communication between the vacuum chamber and the exhausted chamber is cut off. Then, the heating means installed in each cold head gives different amounts of heat to raise the temperature of each cold head, vaporize the condensed and adsorbed gas in each cold head, and supply the vaporized gas into the vacuum chamber. A method for regenerating a cryopump, which is characterized in that it is discharged together with a regenerating gas. 2. In a cryopump for removing gas by condensing and adsorbing gas to a plurality of cryogenic cold heads having different cooling temperature levels and heat capacities installed in the vacuum chamber, communication between the vacuum chamber and the exhausted chamber is performed. Is cut off and the amount of heat based on the difference in cooling temperature and heat capacity of the cold head is given by the heating means installed in each cold head to raise the temperature of each cold head and the temperature difference of the cold head is controlled below a predetermined value. Then, the cryopump regeneration method is characterized in that the condensed and adsorbed gas is vaporized in each cold head, and the vaporized gas is discharged together with the regeneration gas supplied into the vacuum chamber.