JPH07310657A - Evacuating device - Google Patents

Abstract

PURPOSE:To provide a vacuum exhaust device which is constituted to have high exhaust capacity for hydrogen gas and provide excellent exhaust capacity even at a very low pressure. CONSTITUTION:In a vacuum exhaust device comprising a single or a plurality of on-off valves, a single or a plurality of mechanical vacuum pumps, and an exhaust pipe through which the above are interconnected, palladium is used as a material for a part of the pipe wall of an exhaust pipe 7 connected to the exhaust port 4-1a of a mechanical vacuum pump 4-1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum exhaust device for exhausting gas in a vacuum container, and more particularly to a vacuum exhaust device suitable for high-speed exhaust of hydrogen gas in a high vacuum.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a configuration example of a conventional vacuum exhaust device of this type. In the figure, reference numeral 1 denotes a vacuum container, and a main pump 4-1 and an auxiliary pump 4-2 are arranged in series in order to exhaust the inside of the vacuum container 1 to a high vacuum, and an exhaust pipe 7 is provided.
Are connected with. An exhaust pipe solenoid valve 5 is provided in the exhaust pipe 7 between the main pump 4-1 and the auxiliary pump 4-2. The vacuum vessel 1 and the auxiliary pump 4-2 are connected by a roughing line 8 and a roughing line solenoid valve 6 is provided on the way.

The gate valve 2 opens and closes the vacuum container 1 and the exhaust system, and is provided between the vacuum container 1 and the main pump 4-1. The main pump 4-1 sucks the gas in the vacuum container 1 in a high vacuum, boosts the pressure, and exhausts the gas in a low vacuum or a medium vacuum from an exhaust port 4-1a. When the pressure inside the vacuum container 1 is atmospheric pressure,
By closing the gate valve 2 and opening the roughing line solenoid valve 6 of the roughing line 8, the gas in the vacuum container 1 can be roughly pulled by the auxiliary pump 4-2.

[0004]

As a high vacuum pump, a cryopump and a turbo molecular pump are widely used at present. A cryopump mainly cools a cooling plate or activated carbon attached to the cooling plate to a cryogenic temperature by a Gifford-McMahon refrigerator or a Stirling refrigerator, and this cooling plate removes gas molecules such as oxygen, nitrogen, carbon dioxide and water vapor. It is a vacuum pump that traps by freezing, and the activated carbon attached to the cooling plate physically adsorbs hydrogen gas mainly to obtain a high vacuum. This pump has the following drawbacks with respect to hydrogen gas.

(1) The exhaust speed of hydrogen gas is slow, (2) the duration of hydrogen exhaust is short, and regeneration (work of stopping the vacuum pump exhaust operation and vaporizing and exhausting trap molecules) must be performed frequently. (3) In addition, it takes a long regeneration time to completely regenerate the hydrogen gas physically adsorbed on the activated carbon.

The turbo-molecular pump mainly comprises a rotor having a turbine blade cascade of 20 to 30 stages and 20,000 to 50,000.
It is a vacuum pump that compresses and evacuates high vacuum gas by rotating it at high speed at 0 rpm. This turbo molecular pump also has a problem that the exhaust capacity for hydrogen gas is low.

A compression ratio for each gas is an element for evaluating the exhaust speed of the turbo molecular pump. Here, the compression ratio is the ratio of the pressure on the exhaust side to the pressure on the intake side of the turbo molecular pump, and the movement speed of the gas molecules, the rotation speed of the turbine blade cascade of the rotor, and the number of stages are the determining factors. The movement speed of hydrogen gas is very high, and the compression ratio of the turbo molecular pump to hydrogen gas is inevitably small. Under the present circumstances, when the hydrogen partial pressure in the vacuum container 1 becomes lower than a predetermined pressure, the exhaust rate of hydrogen rapidly decreases.

When the pressure in the vacuum container 1 is in the medium vacuum to high vacuum region, the main component of the residual gas in the vacuum container 1 is usually steam. When the pressure in the vacuum container 1 is further lowered by evacuation for a longer time or baking of the vacuum container, the hydrogen ratio of the residual gas in the vacuum container 1 becomes higher. When the pressure inside the vacuum container 1 is to be lowered, the ability of the vacuum pump to exhaust hydrogen is a major factor.

Further, in the ion implantation apparatus and the sputtering apparatus of the semiconductor manufacturing apparatus, the water molecules in these vacuum vessels are decomposed into hydrogen gas, and the hydrogen molecules in the vacuum vessels become high, so that the vacuum used for these is used. A pump or an exhaust device is required to have a high exhaust capacity for hydrogen gas.

The present invention has been made in view of the above points, and an object thereof is to provide a vacuum exhaust device having a high exhaust capacity for hydrogen gas and realizing an excellent exhaust capacity even at an extremely low pressure. To do.

[0011]

In order to solve the above-mentioned problems, the present invention provides a vacuum exhaust system including a single or plural open / close valves, a single or plural mechanical vacuum pumps, and an exhaust pipe connecting these mechanical pumps. It is characterized in that palladium is used for a part of the material of the wall of the exhaust pipe connected to the exhaust port of the vacuum pump.

Further, the main pump of the single mechanical vacuum pump or the plurality of mechanical vacuum pumps is a turbo molecular pump, and one of the exhaust pipe of the main pump or one of the wall of the exhaust pipe connecting the main pump and the auxiliary pump. It is characterized in that palladium is used as the material of the part.

A heater is installed near the tube wall made of palladium.

Further, a gas having a low hydrogen partial pressure is introduced into the atmosphere side of the tube wall using palladium, and the gas on the atmosphere side of the tube wall using palladium is forcibly replaced by the gas having a low hydrogen partial pressure. It is characterized by

[0015]

[Function] The palladium plate has a property of easily passing only hydrogen gas. In particular, the heated and heated palladium plate allows hydrogen gas to permeate very well. Since the present invention uses palladium as a part of the material of the pipe wall of the exhaust pipe connected to the exhaust port of the mechanical vacuum pump as described above, the hydrogen gas in the exhaust gas flowing through the exhaust pipe is Since it permeates the tube wall and is discharged to the outside air, the partial pressure of hydrogen gas in the exhaust pipe becomes extremely low. As a result, the hydrogen gas can be efficiently exhausted until the hydrogen partial pressure in the vacuum container on the intake side of the mechanical vacuum pump becomes even lower due to the relationship of the compression ratio of the mechanical vacuum pump to various gases. .

Here, for reference, let us consider the hydrogen partial pressure in the exhaust pipe in which the palladium pipe wall can be exhausted to the atmosphere based on the average composition of the atmosphere. Hydrogen gas is contained in the air at an average of 0.5 ppm in volume composition comparison. Based on this, the partial pressure of hydrogen gas in the atmosphere is about 5 × 1/10 ² Pa
Becomes When the hydrogen partial pressure in the exhaust pipe becomes higher than this, hydrogen gas is released to the atmosphere through the palladium pipe wall.
Further, by covering the atmospheric pressure side of the palladium pipe wall with a gas having a low hydrogen partial pressure, it becomes possible to release hydrogen gas having a lower partial pressure from the exhaust pipe to the outside air.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a vacuum exhaust device of the present invention. In FIG. 1, reference numeral 1 denotes a vacuum container. In order to create a high vacuum in the vacuum container 1, a turbo molecular pump is used as the main pump 4-1 and a roots pump is used as the auxiliary pump 4-2. -1 and the auxiliary pump 4-2 are connected in series by the exhaust pipe 7. An exhaust pipe electromagnetic valve 5 is provided in the exhaust pipe 7 between the main pump 4-1 and the auxiliary pump 4-2, and the palladium unit 10 is provided in the exhaust pipe 7 between the exhaust pipe electromagnetic valve 5 and the auxiliary pump 4-2. Is provided.

The vacuum container 1 and the auxiliary pump 4-2 are connected by a roughing line 8 and a roughing line solenoid valve 6 is provided on the way. The gate valve 2 opens and closes the vacuum container 1 and the exhaust system, and is provided between the vacuum container 1 and the main pump 4-1 which is a turbo molecular pump. When stopping the exhaust of the gas in the vacuum container 1, the gate valve 2 is closed. When the main pump 4-1 is stopped, the gate valve 2 and the exhaust pipe solenoid valve 5 are closed so that the main pump 4-1 which is a turbo molecular pump is always stored in a vacuum.

The roughing line 8 and the roughing line solenoid valve 6 are
When the pressure in the vacuum container 1 is atmospheric pressure, the gate valve 2 and the exhaust pipe electromagnetic valve 5 are closed, the roughing line electromagnetic valve 6 is opened, and the gas in the vacuum container 1 is removed by the auxiliary pump 4-2. It is for roughing to a low vacuum or a medium vacuum region.

In a normal continuous operation, the roughing line solenoid valve 6 is closed and the gate valve 2 and the exhaust pipe solenoid valve 5 are opened. In the palladium unit 10, the gas in the vacuum container 1 is sucked and compressed by the main pump 4-1 which is a turbo molecular pump, and only the hydrogen gas of the exhaust gas discharged to the exhaust pipe 7 is discharged to the outside of the exhaust system. is there. This is because palladium can pass only hydrogen gas, and statistically a large number of hydrogen molecules flow from the higher partial pressure of hydrogen gas to the lower partial pressure of hydrogen gas.

In the vacuum exhaust device having the above-mentioned structure, the partial pressure of hydrogen gas in the exhaust pipe 7 connected to the exhaust port 4-1a of the main pump 4-1 is higher than that outside the exhaust system, that is, the atmosphere. Discharges the hydrogen gas in the exhaust pipe 7 to the outside of the system to reduce the hydrogen partial pressure at the exhaust port 4-1a of the main pump 4-1. Main pump 4 which is a turbo molecular pump
Since -1 has the ability to exhaust various gases at a predetermined compression ratio, as the hydrogen partial pressure at the exhaust port 4-1a of the main pump 4-1 decreases, the inside of the vacuum container 1 on the intake port side is reduced. The hydrogen gas can be exhausted to a lower partial pressure.

As described above, according to the vacuum exhaust device having the above structure, the hydrogen gas in a high vacuum can be actively exhausted, the ultimate pressure of the vacuum container 1 can be further lowered, and the vacuum exhaust can be performed. The time required for can be shortened.

FIG. 2 is a diagram showing a structural example of the palladium unit 10. In the figure, the connecting pipe 25 is a pipe connected to the exhaust pipe 7. Reference numeral 21 is a palladium tube, and the palladium tube 21 is a cylindrical tube made of a palladium material. Multiple palladium tubes 21 (4 in the figure)
Are two disc-shaped plates 2 at both ends
The inside of the palladium tube 21 is open to the atmosphere. The two plates 23 are attached to the upper and lower ends of a cylindrical unit body 24 in an airtight manner, and the unit body 24 and the upper and lower two plates 23 connect a connecting pipe 25.
A vacuum container communicating with the exhaust pipe 7 is formed.

A heater case 27 is provided at the center of the palladium unit 10, and a cartridge heater 22 is housed in the heater case 27. An electric wire 26 is connected to the cartridge heater 22 so that a heating current can be supplied from a power source (not shown). The hydrogen gas in the unit case 24 penetrates inside through the wall of the palladium tube 21 and is released to the atmosphere. Cartridge heater 2
2 is located in the center of a plurality of palladium tubes 21 arranged, and the cartridge heater 22 heats the palladium tubes 21 to facilitate the permeation of hydrogen gas through the palladium tubes 21.

FIG. 3 is a diagram showing another configuration example of the palladium unit 10. In the figure, the present palladium unit 10 is configured such that the introduction gas 32 is used in the palladium unit 10 shown in FIG. 2 to forcibly discharge the hydrogen gas discharged into the palladium pipe 21 to the outside. That is, the introduction gas chamber 33 is provided below the plate 23 at the lower end.
By introducing the introduction gas 32 from the introduction gas pipe 31 into the introduction gas chamber 33, the introduction gas 32 enters the palladium pipe 21 from the lower end and is released to the atmosphere.

The atmosphere contains a small amount of hydrogen gas, and the exhausted hydrogen gas remains in the palladium tube 21, which increases the partial pressure of hydrogen in the palladium tube 21. Since the ability of hydrogen to permeate the wall of the pipe decreases, a gas with a low hydrogen partial pressure is used as the introduction gas 32 and the palladium pipe
The gas in 1 is constantly replaced. As a result, the hydrogen partial pressure in the palladium pipe 21 of the palladium unit 10 is always kept extremely low, so that the hydrogen gas in the exhaust pipe 7 of the exhaust system permeates the pipe wall of the palladium pipe 21 and is efficiently discharged to the atmosphere. To be done.

In the above embodiment, the palladium unit 10 connected to the exhaust pipe 7 is provided as means for using palladium as a material of a part of the wall of the exhaust pipe connected to the exhaust port of the vacuum pump. Although the configuration in which the palladium pipe 21 is arranged in the unit 10 is adopted, the means of using palladium for a part of the material of the exhaust pipe wall is not limited to this, and the point is that hydrogen in the exhaust pipe is a palladium material. It may be configured such that it is permeated through the tube wall made of and is discharged to the atmosphere.

[0028]

As described above, according to the present invention, since palladium is used as a part of the material of the pipe wall of the exhaust pipe connected to the exhaust port of the mechanical vacuum pump, the hydrogen gas in the exhaust pipe is It is released to the outside through the wall of the palladium tube, and the effect of being able to enhance the exhaust capability of the mechanical vacuum pump for hydrogen gas is obtained.

Further, a gas having a low hydrogen partial pressure is introduced into the atmosphere side of the tube wall using palladium, and the gas on the atmosphere side of the tube wall using palladium is forcibly replaced with the gas having a low hydrogen partial pressure. As a result, the exhaust capacity of the mechanical vacuum pump for hydrogen gas can be further increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a vacuum exhaust device of the present invention.

FIG. 2 is a diagram showing a configuration example of a palladium unit.

FIG. 3 is a diagram showing another configuration example of a palladium unit.

FIG. 4 is a diagram showing a configuration example of a conventional vacuum exhaust device.

[Explanation of symbols]

 1 Vacuum container 2 Gate valve 4-1 Main pump 4-2 Auxiliary pump 5 Exhaust pipe solenoid valve 6 Roughing line solenoid valve 7 Exhaust pipe 8 Roughing line 10 Palladium unit 21 Palladium pipe 22 Cartridge heater 23 Plate 24 Unit body 25 Connection Pipe 26 Electric wire 27 Heater case 31 Introduced gas pipe 32 Introduced gas 33 Introduced gas chamber

Claims (4)

[Claims] 1. A vacuum exhaust device comprising one or a plurality of on-off valves, one or a plurality of mechanical vacuum pumps, and an exhaust pipe connecting these, wherein a pipe of an exhaust pipe connected to an exhaust port of the mechanical vacuum pump. An evacuation device characterized by using palladium for part of the wall material. 2. The main pump of the single mechanical vacuum pump or the plurality of mechanical vacuum pumps is a turbo molecular pump, and an exhaust pipe of the main pump or a pipe wall of an exhaust pipe connecting the main pump and the auxiliary pump is provided. The vacuum exhaust apparatus according to claim 1, wherein palladium is used as a part of the material. 3. The vacuum evacuation device according to claim 1, wherein a heater is installed near the tube wall made of palladium. 4. A gas having a low hydrogen partial pressure is introduced into the atmosphere side of the tube wall using palladium, and the gas on the atmosphere side of the tube wall using palladium is forcibly replaced with the gas having a low hydrogen partial pressure. An evacuation device characterized by: