JPH10266959A - Evacuation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make improvements in the conservation of environment and the reliability and safety of operation, in addition to the abatement of equipment and operation cost by preventing the emission of such gas as PFC or the like to the stmosphere, and simultaneously aiming at the lightening the burden of an exhaust gas disposal unit and the promotion of long-livedness in a vacuum pump. SOLUTION: A trap unit 20, provided with a trap chamber 32a trapping the constituent element of exhaust gas in a trap part 18 and a regenerative chamber 34a regenerating the constituent element trapped, is installed in an exhaust path 14 lying between a vacuum chamber 10 and a vacuum pump 12, and a regenerative path 16 extending from this regerative chamber is provided with an exhaust gas disposal unit 22 and a gas storage vessel 24 storing such a gas as being nondisposable in this exhaust gas processing unit both.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum exhaust system used to evacuate a vacuum chamber of, for example, a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art A conventional vacuum exhaust system will be described with reference to FIG. Here, the vacuum chamber 101 is
For example, it is a process chamber used for a semiconductor manufacturing process such as an etching apparatus and a chemical vapor deposition apparatus (CVD). The vacuum chamber 101 is connected to a vacuum pump 103 through a pipe 102. The vacuum pump 103 is for increasing the pressure of the exhaust gas of the process from the vacuum chamber 101 to the atmospheric pressure. Conventionally, an oil rotary pump is used, and at present, a dry pump is mainly used.

When the degree of vacuum required by the vacuum chamber 101 is higher than the ultimate degree of vacuum of the dry pump 103,
An ultra-high vacuum pump such as a turbo molecular pump may be further arranged upstream of the dry pump. Since the exhaust gas of the process is toxic or explosive depending on the type of process,
It cannot be released to the atmosphere as it is. Therefore, the vacuum pump 1
An exhaust gas treatment device 104 is provided downstream of the exhaust gas treatment device 03. Among the exhaust gas of the process whose pressure has been increased to the atmospheric pressure, those which cannot be released to the atmosphere as described above are subjected to treatments such as adsorption, decomposition and absorption, and only harmless gases are released to the atmosphere. The pipe 102 is provided with a valve at an appropriate position as needed.

[0004]

Here, PFC gases such as CF ₄ and C ₂ F ₆ used in a semiconductor manufacturing process are harmless to the human body, but harmful to the global environment. It has been known that it is desired to prevent the release to the atmosphere by some method. However, in the conventional vacuum exhaust system, the PFC gas cannot be processed by the exhaust gas treatment device and is released to the atmosphere. At present, it was unable to respond to requests.

Moreover, since the exhaust gas treatment device is located downstream of the vacuum pump, the N
_{2 The} gas flows into the exhaust gas treatment device together with the exhaust gas,
Not only will this lead to an increase in size, but also the running cost will increase.

[0006] When a substance having a high sublimation temperature is contained in the reaction product in the vacuum chamber, when exhaust gas is exhausted by the vacuum pump, the gas solidifies during the pressurization in the pump, and the gas is solidified. There is a problem that it precipitates inside and causes a failure of the vacuum pump.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to prevent the release of gases such as PFC into the atmosphere, reduce the load on an exhaust gas treatment device, extend the life of a vacuum pump, and protect the environment. , Improving driving reliability and safety,
It is another object of the present invention to provide a vacuum exhaust system capable of reducing equipment and operating costs.

[0008]

According to the first aspect of the present invention, a trap chamber for trapping a component of exhaust gas in a trap section in an exhaust path for exhausting from a vacuum chamber, and a component trapped in the trap section are regenerated. An evacuation system comprising: a trap device having a regeneration chamber; and an exhaust gas treatment device and a gas storage container for storing gas that cannot be processed by the exhaust gas treatment device are provided in a regeneration path extending from the regeneration chamber. It is.

Thus, for example, the PFC gas is trapped from the exhaust gas by the trap section of the trap device, is regenerated in the regenerating chamber, is stored in the gas storage container, and is prevented from being released to the atmosphere. Can be achieved. In addition, a trap device is disposed upstream of the vacuum pump to trap a reaction product having a high sublimation temperature, to prevent solids from being deposited in the vacuum pump, and to provide a regeneration path extending from the regeneration chamber. The size can be reduced by providing a gas processing device.

The vacuum chamber is made of, for example, CF ₄ or C ₂ F ₆
This is a process chamber for a semiconductor manufacturing apparatus through which a PFC gas flows. As the vacuum pump, it is preferable to use a dry pump that does not use lubricating oil in order to prevent contamination of the chamber due to back diffusion by oil.

The invention according to claim 2 is the vacuum exhaust system according to claim 1, wherein the trap device is a low-temperature trap that cools the trap portion to precipitate the components.

When the trap portion is configured as a low-temperature trap, there is a method in which a temperature medium is circulated from the outside to the trap portion, such as heat of vaporization of liquefied gas (for example, liquid nitrogen), cooling water, or a refrigerant. There is also a method of generating a low temperature in the trap portion without flowing the temperature medium itself using a thermoelectric element (Peltier element), a pulse tube refrigerator, or the like. For example, the trap section is cooled to about -200 ° C. by a helium refrigerator or the like.

According to a third aspect of the present invention, the regeneration chamber is disposed adjacent to the trap chamber, and the trap section is configured to be switchably movable between the trap chamber and the regeneration chamber. The trap device according to claim 1, wherein the trap device is a trap device. Thus, by moving the trap section in the trap chamber from the trap chamber to the regeneration chamber, the trap and the regeneration can be continuously repeated without removing the trap section. It is also easy to achieve complete automation by using an appropriate switching timing determination unit.

The switching of the trap portion may be performed by an air cylinder. In that case, control may be performed by an air drive control device including a solenoid valve and a speed controller, and further, the air drive control device may be controlled by a control signal from a sequencer or a relay. .

As a method of completely automatically switching the trap portion without manual intervention, for example, a method is provided in which a sensor for detecting a differential pressure across the trap portion is provided, and when a detection value of the sensor reaches a predetermined value. There is a method of performing switching in advance, or a more practical method of setting an appropriate switching time in advance. When the exhaust path and the regeneration gas circulation path are in a one-to-one relationship, the trap and regeneration times are the same, so that it is desirable to increase the regeneration capability over the trap capability so that the regeneration end time is shorter. .

According to a fourth aspect of the present invention, there is provided the vacuum evacuation system according to any one of the first to third aspects, wherein a cleaning liquid path for circulating the cleaning liquid in the regeneration chamber is provided. Thus, the inside of the regeneration chamber can be reliably and quickly cleaned with a cleaning liquid having a high cleaning ability.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows that a regeneration path 16 is arranged adjacent to an exhaust path 14 for evacuating the vacuum chamber 10 by a vacuum pump 12, and a direction intersecting the exhaust path 14 and the regeneration path 16 (hereinafter referred to as a cross direction). Unit 1 that can be moved straight ahead and switchable
8 is provided. The vacuum pump 12 has one stage in this example, but may have multiple stages. An exhaust gas treatment device 19 is disposed in the exhaust path 14 as needed.

As will be described in detail below, the trap device 20 has a trap chamber 32a and a regeneration chamber 34a located in the casing 26.
The trap section 18 moves between and the regeneration chamber 34a. The exhaust path 14 is connected to the trap chamber 32
a and the reproduction path 16 are connected to the reproduction room 34a, respectively.

A regeneration chamber 34a is arranged in parallel with the exhaust path 14.
A cleaning liquid circulation path 70 passing through the inside is provided. That is, the cleaning liquid circulation path 70 is provided with a circulation pump 72 and a cleaning liquid tank 74, and with the driving of the circulation pump 72, the cleaning liquid circulates in the regeneration chamber 34a, and the sublimation temperature of the sublimation temperature adheres to the inside. High by-products and the like are washed with the washing liquid. An exhaust gas treatment device 22 and a gas storage container 24 that is located downstream of the exhaust gas treatment device 16 and stores gas that cannot be treated by the exhaust gas treatment device 22 are disposed in the regeneration path 16.

FIGS. 2 and 3 show the trap device 20, which comprises a rectangular parallelepiped casing 26 disposed over the exhaust path 14 and the regeneration path 16 (and the cleaning liquid circulation path 70). A shaft 28 penetrates the shaft 26 in the cross direction, and an air cylinder 30 as a driving means for reciprocating the shaft 28 in the axial direction. The casing 26 has a trap container 32 whose inside is a trap chamber 32a and a regeneration container 34 whose inside is a regeneration chamber 34a.

The trap container 32 is provided with an exhaust gas inlet 32b connected to the exhaust path 14 for introducing exhaust gas into the trap chamber 32a, and an exhaust gas outlet 32c for discharging exhaust gas in the trap chamber 32a. . The regeneration container 34 is connected to the regeneration path 16 and has a regeneration chamber 34a.
An inlet 34b for injecting a high-temperature regenerating gas into the inside and an outlet 34c for discharging the regenerating gas in the regenerating chamber 34a are provided.

The inlet 34b and outlet 34c of the regenerating container 34 also serve as a liquid inlet and a liquid outlet of the cleaning liquid circulation path 70 shown in FIG. 1, and are driven by a circulation pump 72 shown in FIG. The cleaning liquid is injected into the regeneration chamber 34a from the inlet 34b, and the cleaning liquid is discharged from the outlet 34c.

A pair of seal plates 40 made of a heat insulating material are arranged on the shaft 28, and a plurality of baffle plates 42 are integrally attached to the shaft 28 by welding or the like in order to improve heat conduction. Thus, the trap section 18 is configured. On the side adjacent to the trap container 32 and the regeneration chamber 34, an opening 36 having a size such that the baffle plate 42 can pass but the seal plate 40 cannot pass is provided.
Further, both protruding portions of the shaft body 28 from the casing 26 include:
A bellows 44 is provided to maintain airtightness between the exhaust path 14 and the regeneration path 16 and the external environment.

Both sides of the trap container 32 sandwiching the opening 36, the inner surface facing the opening 36, and the regenerating container 3
In a total of four places of the inner surface facing the opening 36 of 4,
A seal plate storage portion 46 formed in a shape along the outer shape of the seal plate 40 is provided. The sealing plate 40 is formed of a material having high heat insulation, and the trap chamber 32a and the regeneration chamber 34 are formed.
In addition to preventing the heat transfer during the period a, the outer peripheral end face is formed in a circular cross section, and a seal portion 48 is provided here. The sealing portion 48 is formed by fitting an O-ring 50 as a sealing material into a concave portion 40 a provided on the outer peripheral end surface of the sealing plate 40.
When the is located in the seal plate storage portion 46, the O-ring 50 comes into pressure contact with the inner peripheral surface of the seal plate storage portion 46. Here, the inner peripheral surface of the seal plate housing portion 46 is formed in a tapered shape so that the seal plate 40 can easily enter.

Further, a second seal portion 52 is provided on one of the side end surfaces of the seal plate 40 or one of the wall surfaces of the seal plate housing portion 46 with which the side end surface abuts. In this example, the second seal portion 52 is provided on one end surface of one seal plate 40.
An example is shown in which two seal portions 52 are provided in two seal plate storage portions 46, respectively. That is, in the seal plate 40, a ring-shaped concave portion 40b is provided on a side end surface of the seal plate 40, and the O-ring 54 is fitted in the concave portion 40b. Is provided with a ring-shaped recess 46a, and an O ring 54 is provided in the recess 46a.
Are fitted to form the second seal portion 52.

As described above, the sealing plate 40 and the casing 2
6 (the trap container 32 and the regeneration container 34) is double-sealed at the outer peripheral end face and the side end face of the seal plate 40, thereby assuring the integrity of the seal here and the exhaust path 14
And the airtightness of the reproduction path 16 is maintained.

The shaft 28 is formed as a double cylinder made of a material having good thermal conductivity such as metal, and the refrigerant supplied from the refrigerant supply pipe 56 passes through the inside of the pipe inside the shaft 28. After that, it flows through the gap between the two pipes and is discharged from the refrigerant discharge pipe 58, whereby the baffle plate 42 is cooled. Here, as the refrigerant, for example, a liquid such as liquid nitrogen or cooled air or water is used. At the time of regeneration, the supply of the refrigerant may be stopped, and a heating heat medium for regeneration may be circulated instead of the refrigerant.

The air pipe for driving the air cylinder 30 is as shown in FIG. That is, the air from the air source is depressurized by the regulator 80, sent to the solenoid valve 82, and controlled to be opened or closed by an electromagnetic signal, sent to the cylinder 30, and the piston moves forward or backward. The driving speed of the cylinder 30 at this time is controlled by the speed controller 84. In this example, the solenoid valve 82 is controlled by a control signal from a sequencer, a relay, or the like so that the switching operation is performed at regular intervals.

A temperature sensor 66 is provided at a predetermined position on the baffle plate 42 or the like of the trap section 18, and a pressure sensor 68 is provided before and after the trap section 18 in the exhaust gas circulation path 16, thereby detecting a temperature and a differential pressure. You can do it.

Next, the operation of the vacuum exhaust system according to the embodiment of the present invention having the above-described configuration will be described. In the position shown in FIG. 2, a coolant such as liquid nitrogen, cooling air, or water is supplied from a coolant supply pipe 56 to the trap portion 18 located in the trap chamber 32a. The plate 42 is cooled. Therefore, components such as PFC gas and by-products having a high sublimation temperature in the exhaust gas that comes into contact therewith are deposited here, adhered to them, and trapped.

After the elapse of a predetermined time, the air cylinder 30 is operated, and as shown in FIG. 3, the trap portion 18 in the trap chamber 32a is switched so as to be located in the regeneration chamber 34a. The regeneration gas is introduced, and the temperature of the baffle plate 42 is raised. Then, the precipitates trapped in the trap section 18 are vaporized again, and the vaporized regeneration gas is guided to the exhaust gas treatment device 22 along the regeneration path 16 and subjected to the detoxification processing. PFC gas or the like that cannot be processed by the exhaust gas processing device 22 is stored in the gas storage container 24. In this state, if necessary, the cleaning liquid is injected into the regeneration chamber 34a through the cleaning liquid circulation path 70, whereby the by-products having a high sublimation temperature deposited inside the regeneration chamber 34a are washed with the cleaning liquid.

In this way, the PFC gas, which is bad for the global environment, is prevented from being released to the atmosphere and reused, and the cleaning liquid circulation path 70 is provided to easily and quickly clean the inside of the regeneration chamber 34a. can do.

Here, since the sealing plate 40 has a heat insulating property, and the trap chamber 32a and the regeneration chamber 34a are insulated from each other, there is no loss of heat energy, and trap and regeneration can be performed efficiently, respectively. . In addition, since both protruding portions of the shaft body 28 are kept airtight by the bellows 44 that expand and contract, energy loss due to heat transfer to and from the outside and a reduction in processing efficiency are suppressed, and a stable trap and regeneration processing can be performed. In addition, the contamination element from the outside is prevented from entering the exhaust path 14.

As a cooling means for the trap,
Thermoelectric element that cools by thermoelectric effect (Peltier element)
It is a matter of course that a cooler using the above may be used. This type of cooler is constructed by placing a thermoelectric element at a distance between two metal plates.

In the above-described embodiment, the trap portion 18 can be switched by moving linearly in the casing 26. However, the casing is formed in an annular shape, and the trap portion is moved by rotating the trap portion. May be. In this case, three or more trap portions 18 are provided for one exhaust path, and the gas can be simultaneously reproduced in two or more regeneration chambers. This is particularly advantageous since the regeneration speed is usually slower than the trap speed.

[0036]

As described above, according to the present invention, it is possible to prevent a gas which cannot be treated by an exhaust gas treatment device such as a PFC and has an adverse effect on the global environment from being released into the atmosphere. Can be recovered and reused with high purity. In addition, by reducing the amount of gas flowing into the exhaust gas treatment device, the size can be reduced, and by-products flowing into the vacuum pump are trapped in front of the pump so that the by-products are fixed in the vacuum pump. And stable operation for a long period of time can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of an evacuation system according to one embodiment of the present invention.

FIG. 2 is a partially cutaway front view showing a trap device used in the embodiment of FIG. 1;

3 is a partially cutaway front view showing a state after the switching of the trap device of FIG. 2; FIG.

FIG. 4 is a diagram showing a drive system of an air cylinder.

FIG. 5 is a diagram showing the structure of a conventional evacuation system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vacuum chamber 12 Vacuum pump 14 Exhaust path 16 Regeneration path 18 Trap part 20 Trap device 22 Exhaust gas treatment device 24 Gas storage container 26 Casing 28 Shaft 30 Air cylinder (drive means) 32 Trap container 32a Trap chamber 34 Regeneration container 34a Regeneration chamber 42 Baffle plate 46 Seal plate storage part 48, 52 Seal part 70 Cleaning liquid circulation path 72 Circulation pump

Claims (4)

[Claims] 1. A trap device having a trap chamber for trapping components of exhaust gas in a trap section and a regeneration chamber for regenerating trapped components is provided in an exhaust path between a vacuum chamber and a vacuum pump; An exhaust gas treatment device and a gas storage container for storing gas that cannot be processed by the exhaust gas treatment device are provided in a regeneration path extending from the exhaust gas treatment device. 2. The vacuum evacuation system according to claim 1, wherein the trap device is a low-temperature trap that cools the trap portion to precipitate the components. 3. The regeneration chamber according to claim 1, wherein the regeneration chamber is disposed adjacent to the trap chamber, and the trap section is configured to be freely movable between the trap chamber and the regeneration chamber. Or the evacuation system according to 2. 4. The vacuum exhaust system according to claim 1, further comprising a cleaning liquid path for circulating a cleaning liquid in the regeneration chamber.