JPH10176663A - Trap device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a trap ratio, reliability, and durability by arranging a thermoelement for cooling, by electric energy, a baffle arranged so as to be brought into contact with exhaust in an exhaust passage, in a trap part arranged in the exhaust passage for exhausting an air tight chamber by a vacuum pump. SOLUTION: Two trap parts are arranged in an exhaust passage for connecting a chamber and a vacuum pump to each other freely to change into the exhaust passage and a regenerating passage. In each trap part, a fin shaped baffle 34 is installed on an axial body 32 arranged in a casing, an inner cylinder 48 is inserted into an inner space of the axial body 32 so as to form a heat medium flow passage 50. A cooler 52 in which a thermoelement 201 for carrying out cooling by thermoelectric effect is used, is arranged in a space formed between the axial body 32 and the inner cylinder 48. In the case of operation, trap operation and regeneration operation are carried out alternately, the cooler 52 is operated in the trap part during trap operation, cooling gas makes flow into the heat medium flow passage, and thereby, a temperature of a cooling wheel 56 is held to nearly a room temperature, and a cooling plate 58 is cooled in a temperature lower than the room temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A conventional vacuum evacuation will be described with reference to FIG. The vacuum chamber 101 is, for example, a process chamber of a semiconductor growth apparatus such as an etching apparatus and a chemical vapor deposition apparatus (CVD).
02 is connected to the vacuum pump 103. 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 is further arranged upstream of the dry pump 103. Certain components of the process exhaust gas are toxic or explosive depending on the type of process and cannot be released directly to the atmosphere. Therefore, an exhaust gas treatment device 104 is provided downstream of the vacuum pump 103, and those which cannot be released to the atmosphere as described above are subjected to processing such as adsorption, decomposition, absorption, etc., and only harmless gas is released to the atmosphere. . The pipe 102 is provided with a valve at an appropriate position as needed.

[0004]

In the conventional vacuum evacuation system as described above, when a substance having a high sublimation temperature is present in a reaction by-product, the gas is exhausted by a vacuum pump. There is a disadvantage that the gas solidifies and precipitates in the vacuum pump, which causes a failure of the vacuum pump.

For example, when BCl ₃ and Cl ₂ which are typical process gases are used for etching aluminum, BCl ₃ and Cl ₂ are supplied from a process chamber.
The residual gas of the process gas and the reaction by-product of AlCl ₃ are exhausted by the vacuum pump 12.

This AlCl ₃ does not precipitate on the suction side of the vacuum pump due to its low partial pressure, but the partial pressure rises during pressurization and exhaust, and precipitates in the vacuum pump, causing a failure of the vacuum pump. . The same applies to the case of a reaction by-product such as (NH ₄ ) ₂ SiF ₆ or NH ₄ Cl generated from a CVD apparatus for forming a SiN film.

Conventionally, to solve this problem, (1) a vacuum pump is heated to prevent solidified substances from being deposited inside the vacuum pump, and is passed through the vacuum pump in a gaseous state. (2) Provide a water-cooled cooler upstream (intake side) of the vacuum pump to trap precipitates. And other measures have been taken.

[0008] However, the measure (1) is effective in protecting the vacuum pump itself, but solidifies precipitates in the exhaust gas treatment device disposed downstream of the vacuum pump, causing clogging of the packed bed. There was a problem.

In the measure (2), since water is used as a medium, it cannot be cooled to 0 ° C. or less, and the trap performance is not sufficient. In order to obtain a cooling performance higher than this, for example, to obtain a trap temperature of about −30 ° C., an appropriate heat medium having a lower solidification temperature and a refrigerator for cooling the heat medium are required, but the apparatus becomes complicated. However, there has been a problem that equipment and operating costs increase. In addition, a device having a vibration system such as a Gifford McMahon refrigerator has a problem that the maintenance frequency is increased.

The present invention has been made in view of the above-mentioned circumstances, and can obtain a low temperature of about -30.degree. C. with a simple and compact structure, has a high trapping efficiency, and has high reliability and reliability.
It is an object of the present invention to provide a trap device that has high durability and good operability and maintainability.

[0011]

According to the first aspect of the present invention, a trap section is disposed in an exhaust path for exhausting an airtight chamber by a vacuum pump, and the trap section is in contact with exhaust in the exhaust path. And a thermoelectric element for cooling the baffle by electric energy.

As shown in FIG. 1, the thermoelectric element is a refrigerator using electricity as operating energy, and includes a semiconductor element 201 and a power supply lead wire 202 which are arranged at an interval between two metal plates. Have been. When electricity flows from the power supply 203 to the semiconductor element 201, electrons flow in the semiconductor element 201 in the opposite direction. The Peltier effect occurs between the heat radiation side a and the heat absorption side b. By cooling the heat radiation side a with N ₂ or water, a low temperature of about -30 °
Occur on the side.

As described above, a low temperature of about −30 ° C. can be easily obtained by using N ₂ or water as an electric wiring for supplying energy and a heat medium for heat radiation. Since the thermoelectric element is small, it can be easily incorporated into the trap section in the exhaust path, and only a compressor for pumping nitrogen gas or water as a heat medium is required as a drive system. Simple, low equipment cost, good maintenance. Further, the operation is easy, for example, on / off of the cooling operation and control of the temperature are also easy.

According to a second aspect of the present invention, the baffle is mounted on a shaft in a fin shape, the thermoelectric element is mounted inside the shaft, and a heat dissipation surface of the thermoelectric element is mounted on the shaft. 2. The trap device according to claim 1, further comprising a heat medium supply flow path for supplying a heat medium for cooling the heat medium. By forming a thermoelectric element and a heat medium path on the inner surface of the shaft and forming the baffle in a fin shape on the shaft, efficient cooling can be performed with a simple structure.

The invention according to claim 3 is the trap device according to claim 1, wherein a heating means for heating the baffle by electric energy is further incorporated in the shaft body. Thereby, the trap and the reproduction operation can be switched simply by switching the electrical connection.

According to a fourth aspect of the present invention, at least two of the trap sections are provided, and each of the trap sections is arranged so as to be switchable between the exhaust path and a regeneration path for regenerating the trap section. Item 4. The trap device according to item 1. As a result, the trap operation and the regeneration operation are performed alternately, so that the operation of the exhaust system is not stopped even if the trap amount exceeds the capacity of one trap, and
There is no need to prepare a replacement trap.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment shown in FIGS. 2 to 4, a regeneration path 16 is provided adjacent to an exhaust path 14 connecting the chamber 10 and the vacuum pump 12, and the two trap portions 18 and 20 include three-way switching valves 22, 24 and 26. , 28
Are provided so as to be switchable between an exhaust path 14 and a regeneration path 16, respectively. Each of the trap units 18 and 20
As shown in FIG. 3, a shaft 32 is provided inside the airtight casing 30 so as to intersect the flow, and a fin-shaped baffle (baffle plate) 34 is attached to the shaft 32. . The casing 30 includes an inlet 36 and an outlet 38 of the exhaust path 14 and an inlet 4 of the regeneration path 16.
0 and an outlet 42 are provided.

An exhaust gas treatment device 44 for removing exhaust gas is provided downstream of the vacuum pump 12. In the regeneration path 16, the trapped precipitate is heated and vaporized,
Alternatively, a regeneration gas for transporting the vaporized gas is branched and circulated from a regeneration gas source (not shown) via the three-way switching valve 26, and an exhaust gas treatment device 46 is provided on the downstream side.

As shown in FIG. 4 (a), the shaft body 32 is formed as a rectangular cylindrical body made of a material having good heat conductivity such as metal, and a plurality of baffle plates 34 are formed on its outer surface by welding or the like. Thermally integrated, an inner cylinder 48 is provided in the inner space as shown in FIG.
As shown in (b), a heat medium flow path 50 is formed which is inverted from the inside of the inner cylinder 48 on the left end side in the drawing and extends between the inner cylinder 48 and the heat radiating cylinder 54.

As shown in FIG. 4, a cooler 52 using a thermoelectric element (Peltier element) for cooling by a thermoelectric effect is provided in a space between the shaft body and the inner cylinder. That is, a radiator tube 54 is further provided between the shaft body 32 and the inner tube 48, and a radiator plate 56 of the cooler 52 is formed on the radiator tube 54, and a cooling plate 58 is formed of a material having good heat conductivity such as indium. It is attached to the shaft 32 via 60. Further, a heater 62 for regeneration is juxtaposed in the same space as the cooler.

In this embodiment, one trap unit 1
When 8 is performing a trapping operation, the other is performing a reproducing operation. The trap portion during the trap operation is a thermoelectric element 2
The power switch 01 is turned on to operate the cooler 52, and a cooling gas such as nitrogen flows through the heat medium flow path 50 by the operation of a switching valve (not shown). Thereby, the heat sink 5
6 is maintained at about room temperature, while the cooling plate 58
Is cooled to a temperature lower than room temperature by a predetermined temperature determined by the capability of the thermoelectric element 201. The degree of the cooling varies depending on the current flowing through the thermoelectric element 201.

When regeneration is required after performing a predetermined trapping process, the three-way switching valves 22, 24, 26, and 28 of the exhaust path 14 and the regeneration path 16 are switched, and the processing of the trap section 18 is reversed. During the regeneration operation, the cooling gas in the heat medium path 50 is stopped, and the heater 62 is operated. As described above, since cooling and heating are performed by the electric energy, there is an advantage that the apparatus configuration is simple, and the switching operation and the setting operation can be easily performed by opening and closing the switch and adjusting the amount of supplied electricity. The gas generated by the regeneration operation is discharged from the regeneration path 16 and processed by the exhaust gas treatment device 46. Note that heating / cooling of the thermoelectric element 201 can be switched by switching ± of the current. Therefore, if there is a switch for switching ± of the current, the heater 62 is unnecessary.

FIG. 5 shows another embodiment of the present invention. Two regeneration paths 16 are provided on both sides of the exhaust path 14, and the trap unit 1 is provided between the exhaust path 14 and the regeneration path 16.
Means for mechanically switching between 8, 20 are provided.
That is, this switchable trap device includes a rectangular parallelepiped casing 66 disposed over the exhaust path 14 and the regeneration path 16, a shaft 68 penetrating the casing 66 in the cross direction, and a shaft 68 in the axial direction. An air cylinder 70, which is a driving means for reciprocating, is provided. Casing 6
Numeral 6 is divided into three rooms in the cross direction by a partition wall 72, that is, a trap room 74 at the center and a regeneration room 76 on both sides. Each room is connected to the exhaust path 14 or the regeneration path 16 respectively. Tube section 7 having flange 78
9 are formed.

On the shaft body 68, three partition plates 80 made of a material having heat insulating properties are arranged at equal intervals, and a plurality of baffle plates 82 are integrally attached to the shaft body 68 by welding or the like. . An opening 73 is formed in the center of the partition wall 72 of the casing 66, and is formed by a baffle plate 82.
Are allowed to pass through, but the partition plate 80 cannot pass through. Two partition plates 80 on both sides and casing 6
A bellows 84 is provided between the inner surfaces of the walls at both ends of 6 to maintain airtightness between the reproduction path 16 and the external environment. An O-ring (not shown) is disposed at a position of the partition wall 72 in contact with the partition plate 80 to maintain the airtightness between the trap chamber 74 and the regeneration chamber 76. The partition plate 80 is made of a material having a high heat insulating property so as to prevent heat transfer between the trap chamber 74 and the regeneration chamber 76.

This embodiment also has the same structure of the trap portions 18 and 20, except that the heat medium flow path 50 extends from both sides to the central partition plate 80. In this example, since the trap unit itself is switched, the switching is performed quickly, and the heat loss is smaller than in the case where the path is switched by a valve. As a result, the influence of the switching operation on the trap and regeneration work is reduced. be able to.

FIG. 6 shows an embodiment in which a plurality of trap portions 18 are arranged in series in the exhaust direction. Here, one regeneration path 16 is provided below the exhaust path 14. A plurality of (two in the illustrated example) reciprocatingly moved by an air cylinder are provided on a casing 66 formed to extend in the exhaust path direction.
Are provided, and each of them has one trap portion 1.
8 is attached. Each trap section 18 can be independently moved to the trap chamber 74 or the regeneration chamber 76.

Also in this embodiment, the operation is performed in the same manner as in the previous embodiment by switching one of the trap units 18 so as to be located in the trap chamber 74 and the other in the regeneration chamber 76. Although it operates, the apparatus becomes compact because only one reproduction path is required. Furthermore, in this embodiment, there is a flexibility that the number of the trap units 18 that operate according to the situation can be changed.

The regeneration method in this embodiment differs from the previous embodiment in that cleaning is performed with a cleaning liquid. That is, in the regeneration chamber 76, the cleaning liquid supply pipe 16a is opened on the upper side, and the cleaning liquid discharge pipe 16b is provided on the lower side. In this example, a plurality of supply pipes 16a are provided according to the arrangement of the trap portions 18 and 20. An example of a reproducing method in this device is as follows. After switching to the state shown in FIG. 6, an appropriate cleaning liquid for dissolving the precipitate is caused to flow out from the supply pipe, and is discharged from the discharge pipe 16b. This process may be repeated as necessary, the cleaning liquid may be sprayed, or the regeneration chamber 76 may be filled with the cleaning liquid. Further, the above-described steps may be performed by changing the cleaning liquid, or the rinsing step may be performed. Next, by supplying a dry gas and performing the drying step, the liquid is prevented from entering the devices before and after the trap.

In the regeneration step using such a cleaning solution,
Since there is no need to heat the regeneration chamber 76, the trap chamber 7
4 can be reduced in measures for preventing thermal effects. In addition, the regenerating ability is higher and the processing speed is higher than in the case of regenerating precipitates by vaporization. Furthermore, post-processing is generally easier than when regenerating as a gas, and it is particularly convenient when reusing or storing regenerated materials. In the configuration shown in FIG. 6, since the regeneration chamber 76 is located only below the trap chamber 74, there is no possibility that the cleaning liquid flows into the trap chamber 74 due to gravity. Therefore, the apparatus of this embodiment is suitable for regeneration using the cleaning liquid. is there.

[0030]

As described above, the trap device of the present invention uses N ₂ as a heat medium for heat radiation by using a thermoelectric element performing a cooling operation by electric energy.
Alternatively, a low temperature of about −30 ° C. can be easily obtained by using water. Therefore, it is possible to provide a trap device having a simple and compact configuration, high trap efficiency, high reliability and durability, and excellent operability and maintainability. This prevents foreign substances from depositing in the vacuum pump and damaging the sliding parts, and preventing accumulation and clogging in the packed bed of the exhaust gas treatment device, thereby protecting the vacuum pump and the exhaust gas treatment device. Stable operation can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of a thermoelectric element used for a trap device of the present invention.

FIG. 2 is a diagram showing a first embodiment of the trap device of the present invention.

FIG. 3 is a diagram showing an entire configuration of the embodiment of FIG. 2;

FIG. 4 is a sectional view showing a structure of a trap section of the trap device of the present invention.

FIG. 5 is a view showing a second embodiment of the trap device of the present invention.

FIG. 6 is a diagram showing a third embodiment of the trap device of the present invention.

FIG. 7 is a view showing a conventional evacuation apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hermetic chamber 12 Vacuum pump 14 Exhaust path 18, 20 Trap part 32, 68 Shaft body 34, 82 Baffle 50 Heat medium supply path 62 Heating means 201 Thermoelectric element

Claims (4)

[Claims] 1. A trap section is disposed in an exhaust path for exhausting an airtight chamber by a vacuum pump, a baffle disposed in the trap section so as to be in contact with exhaust in the exhaust path, and the baffle is powered by electric energy. A trap device comprising a thermoelectric element for cooling. 2. The heating medium according to claim 2, wherein said baffle is mounted on said shaft in a fin shape, said thermoelectric element is mounted inside said shaft, and said shaft is provided with a heat medium for cooling a heat radiation surface of said thermoelectric element. The trap device according to claim 1, further comprising a heat medium supply passage for supplying the heat medium. 3. The trap device according to claim 1, wherein the shaft further includes heating means for heating the baffle with electric energy. 4. The trap device according to claim 1, wherein at least two of the trap units are provided, and each of the trap units is arranged to be switchable between the exhaust path and a regeneration path for regenerating the trap unit.