JP3630522B2 - Vacuum exhaust system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an evacuation system used to evacuate a vacuum chamber of, for example, a semiconductor manufacturing apparatus.
[0002]
[Prior art]
A conventional evacuation system will be described with reference to FIG. Here, the vacuum chamber 101 is a process chamber used in a semiconductor manufacturing process such as an etching apparatus or a chemical vapor deposition apparatus (CVD), for example, and the vacuum chamber 101 is connected to a vacuum pump 103 through a pipe 102. The vacuum pump 103 is for boosting the exhaust gas of the process from the vacuum chamber 101 to the atmospheric pressure. Conventionally, an oil rotary pump and a dry pump are mainly used.
[0003]
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. The exhaust gas from a process is toxic or explosive depending on the type of the process and cannot be released into the atmosphere as it is. For this reason, an exhaust gas treatment device 104 is provided downstream of the vacuum pump 103. Among the exhaust gases of the process whose pressure has been increased to atmospheric pressure, those that cannot be released into the atmosphere as described above are subjected to treatments such as adsorption, decomposition, and absorption, and only harmless gases are released into the atmosphere. The pipe 102 is provided with a valve at an appropriate place as necessary.
[0004]
[Problems to be solved by the invention]
In such an evacuation system, the exhaust gas exhausted from the vacuum chamber contains material gas and by-products, and therefore it has been strongly desired to recycle the expensive material gas. In the conventional vacuum exhaust system, since all exhaust gas was introduced into the exhaust gas treatment device and processed, separation and reuse were difficult, and it was impossible to meet this demand. .
[0005]
Moreover, if exhaust gas is processed in a lump, the exhaust gas processing device becomes larger and not only equipment costs and running costs increase, but also with a gas processing device such as PFC such as CF ₄ and C ₂ F _6. The gas that cannot be discharged into the atmosphere as it is, has been a problem from the viewpoint of environmental protection.
[0006]
The present invention has been made in view of the above-described circumstances, and while attempting to reuse the material gas contained in the exhaust gas, reduces the burden on the exhaust gas treatment device, and prevents PFC and the like from being released into the atmosphere. An object of the present invention is to provide an evacuation system which can be used.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 includes a vacuum chamber, first and second stage vacuum pumps arranged in series in an exhaust path for exhausting the vacuum chamber, an exhaust port of the first stage vacuum pump, and a shower head. An exhaust gas circulation path connecting the vacuum chamber to the trap chamber, and the exhaust gas circulation path is provided with a trap section for trapping exhaust gas components and a trap chamber for containing the trap section, and the trap section adjacent to the trap chamber. The evacuation system is characterized in that a regeneration chamber for regenerating the trap component is provided.
[0008]
As a result, a part of the exhaust gas exhausted from the vacuum chamber is returned from the exhaust gas circulation path into the vacuum chamber to recycle the unreacted material gas. By removing the specific component (by-product) by trapping in the trap part, adverse effects on the process can be prevented. The components trapped in this trap section are regenerated in the regeneration chamber and discharged from the trap device.
[0009]
The vacuum chamber is, for example, a process chamber of a semiconductor device, and an exhaust gas treatment device for detoxifying the process gas is provided as necessary. As at least the first stage 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.
[0010]
A second aspect of the present invention is the vacuum exhaust system according to the first aspect, wherein the trap device is a low temperature trap that cools the trap portion and deposits the components.
[0011]
When the trap unit is configured as a cold trap, there is a method of circulating a temperature medium from the outside to the trap unit, such as heat of vaporization of liquefied gas (for example, liquid nitrogen), cooling water, refrigerant, or the like. There is also a method of generating a low temperature in the trap part without flowing the temperature medium itself using a thermoelectric element (Peltier element) or a pulse tube refrigerator. When it is performed by circulating liquid nitrogen or a helium refrigerator, the temperature of the trap part can be lowered to about -200 ° C.
[0012]
A third aspect of the present invention is the vacuum exhaust system according to the first or second aspect, wherein the trap portion is configured to be movable between the trap chamber and the regeneration chamber. Accordingly, the trapping operation and the regeneration operation can be continuously repeated without removing the trap portion by moving the trap portion that was in the trap chamber from the trap chamber to the regeneration chamber. It is also easy to achieve complete automation using appropriate movement (switching) timing determination means.
[0013]
The trap unit may be moved (switched) by an air cylinder. In this case, the air drive control device may be controlled by a solenoid valve and a speed controller, and the air drive control device may be controlled by a control signal from a sequencer or a relay. .
[0014]
For example, a sensor that detects a differential pressure before and after the trap portion is provided and the detected value is set to a predetermined value as a method that enables the movement (switching) of the trap portion to be performed completely automatically without manual intervention. There are a method of switching when the time has elapsed, or a method of setting an appropriate switching time in advance as a more practical method. When the exhaust gas circulation path and the recycled material discharge path are in a one-to-one relationship, the trapping and regeneration time are the same, so the regeneration capacity is set higher than the trap capacity so that the regeneration end time is shorter. Is preferred.
[0015]
According to a fourth aspect of the present invention, there is provided a regeneration component discharge path that connects the regeneration chamber and an intake port of the second stage vacuum pump. It is a vacuum exhaust system. Thereby, the regenerated product (by-product) regenerated in the regeneration chamber of the trap device can be discharged to the outside as the second-stage vacuum pump on the downstream side is driven.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows that the vacuum chamber 10 is evacuated by two vacuum pumps, a high vacuum pump (first stage vacuum pump) 12a and a roughing vacuum pump (second stage vacuum pump) 12b connected in series. An exhaust gas circulation path 16 that branches from the pipe 14 that connects both the vacuum pumps 12a and 12b and returns to the vacuum chamber 10 via the shower head 8 is provided. A trap section 18 is provided in the exhaust gas circulation path 16. The trap device 20 having the above is disposed. The shower head 8 injects the source gas supplied from the source gas supply pipe 6 into the vacuum chamber 10.
[0017]
The trap device 20 has a trap chamber 32a and a regeneration chamber 34a in a casing 26, and the trap portion 18 moves between the trap chamber 32a and the regeneration chamber 34a. The trap chamber 32a communicates with the exhaust gas circulation path 16, and a regenerated product discharge path 22 is provided between the regeneration chamber 34a and the pipe 14 connecting the vacuum pumps 12a and 12b. Further, an exhaust gas treatment device 24 for removing exhaust gas is provided at the subsequent stage of the vacuum pump 12b.
[0018]
FIGS. 2 and 3 show a trap device 20, which is a rectangular parallelepiped casing 26 disposed across the exhaust gas circulation path 16 and the regenerated product discharge path 22, and penetrates the casing 26 in the crossing direction. A shaft body 28 and an air cylinder 30 as switching means for reciprocating the shaft body 28 in the axial direction are provided. The casing 26 is mainly composed of a trap container 32 having an interior trap chamber 32a and a regeneration container 34 having an interior regeneration chamber 34a.
[0019]
The trap container 32 is provided with an exhaust gas inlet 32b that is connected to the exhaust gas circulation path 16 and introduces exhaust gas into the trap chamber 32a, and an exhaust gas discharge port 32c that discharges the exhaust gas in the trap chamber 32a. The regeneration container 34 has a gas inlet 34b that is connected to the regeneration discharge path 22 and injects a high-temperature regeneration gas into the regeneration chamber 34a, and a gas exhaust port 34c that exhausts the regeneration gas in the regeneration chamber 34a. Is provided.
[0020]
The shaft body 28 is provided with a pair of sealing plates 40 made of a heat-insulating material, and a plurality of baffle plates 42 are integrally attached to the shaft body 28 by welding or the like in order to improve heat conduction therebetween. A trap unit 18 is configured. On the adjacent side of the trap container 32 and the regeneration chamber 34, there is provided an opening 36 having such a size that the baffle plate 42 can pass but the seal plate 40 cannot pass. Furthermore, the bellows 44 is provided in both the protrusion parts from the casing 26 of the shaft body 28, and the airtightness between the exhaust gas circulation path 16 and the regenerated product discharge path 22 and the external environment is maintained.
[0021]
A total of four locations on both sides of the opening portion 36 of the trap container 32, an inner surface facing the opening portion 36, and an inner surface facing the opening portion 36 of the regeneration container 34 are along the outer shape of the seal plate 40. A seal plate storage portion 46 formed in a shape is provided. The seal plate 40 is made of a highly heat-insulating material so as to prevent heat transfer between the trap chamber 32a and the regeneration chamber 34a, and the outer peripheral end surface is formed in a circular cross section, A seal portion 48 is provided. The seal portion 48 is configured by fitting an O-ring 50 as a seal material in a recess 40a provided on the outer peripheral end surface of the seal plate 40, and when the seal plate 40 is positioned in the seal plate storage portion 46, The O-ring 50 is adapted to come into pressure contact with the inner peripheral surface of the seal plate storage portion 46. The inner peripheral surface of the seal plate housing 46 is formed in a tapered shape so that the seal plate 40 can easily enter.
[0022]
Further, a second seal portion 52 is provided on one of the side end surface of the seal plate 40 or the wall surface of the seal plate housing portion 46 with which the side end surface abuts. In this example, a second seal portion 52 is provided on one end face of one seal plate 40, and a second seal portion 52 is provided on each of three seal plate storage portions 46. That is, a ring-shaped recess 40b is provided on the side end surface of the seal plate 40, and an O-ring 54 is fitted into the recess 40b, and a ring-shaped recess 46a is provided on the wall surface of the seal plate storage portion 46. The second seal portion 52 is configured by fitting the O-ring 54 into the recess 46a.
[0023]
As described above, the sealing plate 40 and the casing 26 (the trap container 32 and the regeneration container 34) are sealed twice by the outer peripheral end face and the side end face of the sealing plate 40, thereby achieving the seal integrity here. Thus, the airtightness of the exhaust gas circulation path 16 and the recycled product discharge path 22 is maintained.
[0024]
The shaft body 28 is formed as a double cylindrical body formed of a material having good thermal conductivity such as metal, and after the refrigerant supplied from the refrigerant supply pipe 56 passes through the inside of the pipe inside the shaft body 28, It flows through the gap between the two tubes and is discharged from the refrigerant discharge tube 58, whereby the baffle plate 42 is cooled. As this refrigerant, for example, liquid such as liquid nitrogen or cooled air or water is used. During regeneration, the supply of the refrigerant can be stopped and a heating heating medium for regeneration can be circulated in place of the refrigerant.
[0025]
The air piping for driving the air cylinder 30 is as shown in FIG. That is, the air from the air source is depressurized by the regulator 60, sent to the solenoid valve 62, controlled by switching of opening and closing by the electromagnetic signal, and 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 64. The solenoid valve 62 is controlled so that the switching operation is performed at regular intervals in this example by a control signal from, for example, a sequencer or a relay.
[0026]
A temperature sensor 66 is provided at a predetermined position such as the baffle plate 42 of the trap portion 18 and a pressure sensor 68 is provided before and after the trap portion 18 of the exhaust gas circulation path 16, thereby detecting the temperature and the differential pressure. It can be done.
[0027]
Next, the operation of the vacuum exhaust system according to the embodiment of the 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, specific components in the exhaust gas that have come into contact therewith are deposited and attached to these and trapped.
[0028]
On the other hand, the component adhering to the trap portion 18 is regenerated in the regeneration chamber 34a, and the regenerated product (byproduct) regenerated in the regeneration chamber 34a is regenerated product discharge path 22 as the vacuum pump 12b is driven. Is discharged to the outside. As a result, by-products captured by the trap unit 18 are periodically discharged to the outside, and the trap chamber 32a is prevented from being blocked by by-products and the trap efficiency of the trap unit 18 is reduced. Can do.
[0029]
As a result, components such as by-products in the exhaust gas flowing along the exhaust gas circulation path 16 are removed by the trap unit 18, and adverse effects on the process can be prevented. The gas from which the by-product is removed and the concentration of the material gas is increased is reintroduced as a raw material gas into the vacuum chamber 10 through the exhaust gas circulation path 16 and the shower head 8. Thereby, reuse of the material gas contained in exhaust gas can be aimed at, and two effects, reduction of processing cost and reduction of raw material cost, can be acquired.
[0030]
After a predetermined time has elapsed, as shown in FIG. 3, the air cylinder 30 is switched so that the trap portion 18 in the trap chamber 32a is positioned in the regeneration / cleaning chamber 34a. Then, a high-temperature regeneration gas is injected into the regeneration chamber 34a from the gas injection port 34b, and the trapped precipitate is vaporized again. The vaporized gas flows through the recycled material discharge path 22 as the vacuum pump 12b is driven, and is discharged after being detoxified in the exhaust gas treatment device 24, or is circulated or stored for reuse. The
[0031]
The sealing plate 40 has a heat insulating property, and the trap chamber 32a and the regeneration chamber 34a are insulated from each other. Therefore, there is no loss of heat energy, and trapping and regeneration are performed efficiently. In addition, since both projecting portions of the shaft body 28 are maintained airtight by the expanding and contracting bellows 44, energy loss due to heat transfer to the outside and a reduction in processing efficiency are suppressed, and stable trapping and regeneration processing can be performed. In addition, contamination elements from the outside are prevented from entering the exhaust gas circulation path 16.
[0032]
Of course, a cooler using a thermoelectric element (Peltier element) for cooling by the thermoelectric effect may be used as a cooling means for the trap. This type of cooler is configured by arranging thermoelectric elements at intervals between two metal plates.
[0033]
【The invention's effect】
As described above, according to the present invention, the material gas can be extracted from the exhaust gas by removing the by-products, and returned to the vacuum chamber for efficient reuse. Therefore, the reduction of exhaust gas treatment costs and the reduction of raw material costs can be achieved at the same time, for example, the semiconductor manufacturing cost can be greatly reduced, and an external system of gas that cannot be processed by an exhaust gas treatment device such as PFC. Environmental protection can be realized by suppressing release to the environment.
[Brief description of the drawings]
FIG. 1 is a diagram showing a structure of an evacuation system according to an embodiment of the present invention.
FIG. 2 is a front view of the trap device used in the embodiment of FIG.
FIG. 3 is a partially cutaway front view showing a state after switching of the trap device of FIG. 2;
FIG. 4 is a view showing a drive system of an air cylinder.
FIG. 5 is a diagram showing a structure of a conventional vacuum exhaust system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Vacuum chamber 12a, 12b Vacuum pump 14 Piping 16 Exhaust gas circulation path 18 Trap part 20 Trap apparatus 22 Recycled material discharge path 26 Casing 28 Shaft body 30 Air cylinder (drive means)
32 Trap container 32a Trap chamber 34 Regeneration container 34a Regeneration chamber 42 Baffle plate 46 Seal plate storage portion 48, 52 Seal portion

Claims (4)

A vacuum chamber;
A first stage and a second stage vacuum pump arranged in series in an exhaust path for exhausting this;
An exhaust gas circulation path connecting the exhaust port of the first stage vacuum pump and the vacuum chamber via a shower head;
The exhaust gas circulation path is provided with a trap portion for trapping exhaust gas components and a trap chamber for containing the trap portion.
An evacuation system, wherein a regeneration chamber for regenerating the trap component of the trap portion is provided adjacent to the trap chamber. The vacuum exhaust system according to claim 1, wherein the trap device is a low-temperature trap that cools the trap portion and deposits the component. The evacuation system according to claim 1 or 2, wherein the trap section is configured to be movable between the trap chamber and the regeneration chamber. The vacuum exhaust system according to any one of claims 1 to 3, further comprising a regeneration component discharge path that connects the regeneration chamber and an intake port of the second stage vacuum pump.

Images