JPH0342010A - Fine particle trap for vacuum evacuation system - Google Patents

Abstract

PURPOSE:To easily wash an equipment without disassembling the equipment and to discarge and recove fine particles by constituting a vessel of double cylindrical bodies consisting of a high temp. wall and a low temp. wall, forming a flow passage between these cylindrical bodies, and exfoliating the particles stuck to the low temp. wall with fluid jets. CONSTITUTION:The vessel 1 is constituted of double cylindrical boding 2, 3 which is provided with the influent pipe 6 connected with a vacuum chamber 8 and with the effluent pipe 10 connected with a vacuum pump 12. The flow passage 4 for flowing gas is formed between the double cylindrical bodies, and the inner cylindrical body 3 of double cylindrical bodies is used as the high temp. wall and the outer cylindrical body 2 is used as the low temp. wall, and the fluid jet nozzles 17 jetting fluid against the surface of the cylindrical body 3 of the low temp. wall is provided along the surface of the cylindrical body 2. The nozzles 17 are connected with a fluid supply unit 19, and the unit 20 which discharges and recovers the fluid jetted from the nozzles 17 and the particles retained in the vessel 1 is provided in the vessel 1. As a result, the fine particles can be discharged and recovered by cleaning the equipment without disassembling the equipment.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a vacuum pump installed between a vacuum chamber and a vacuum pump, so that fine particles such as dust existing in the vacuum chamber can be collected before reaching the vacuum pump. The present invention relates to a particulate trap for vacuum evacuation systems.

[Conventional technology]

Conventionally, when using a vacuum pump to evacuate the vacuum chamber of a film deposition system that generates a large amount of dust, a mesh is inserted in the exhaust passage to protect the vacuum pump, and the mesh is used to remove the dust in the exhaust gas. Alternatively, a drum is provided that rotates in oil in the exhaust passage, and dust in the exhaust gas is deposited on the surface of the drum or on the surface of small objects housed in the drum. In addition, in ultrafine particle production equipment, the generated ultrafine particles are collected by being deposited in a collection chamber.

With conventional meshes and those that pass exhaust gas through a drum rotating in oil, the Raynozzle number is small because the exhaust gas is at low pressure, and the flow condition is laminar and turbulent diffusion cannot be expected. Collection of dust (R particles) relied on the action of the Brownian diffusion effect.

In this case, in order to remove enough dust, it is necessary to make the exhaust road narrow so that the dust can easily adhere to the surface of the passage, and also to ensure the flow rate necessary for the film forming equipment to allow the exhaust gas to flow. , a large pressure difference is required for the passage of exhaust gas. However, this pressure difference causes the disadvantage that the vacuum suction force applied to the vacuum chamber by the vacuum pump is reduced or consumed during the process, and the pressure in the vacuum chamber of the film forming apparatus increases. (In order to achieve this, an additional high-vacuum pump is required between the vacuum chamber and the There was a problem in that it was difficult to remove it.

As mentioned above, removing dust sufficiently and reducing the pressure difference are not compatible, so a compromise has to be made, and as a result, the required pressure difference cannot be made too small. Therefore, it is often difficult to install a dust collection trap between the vacuum chamber of the film forming apparatus and a medium vacuum pump, such as a mechanical booster pump.

The reason for this is that when a trap with a large pressure difference is installed between a medium vacuum pump and a vacuum chamber, the vacuum suction force (ultimate degree of vacuum) of the medium vacuum pump effectively acts on the vacuum chamber due to the pressure difference between the traps. This is because they will no longer do so.

Therefore, if the pressure difference required to pass through the dust collection trap cannot be made sufficiently small, it becomes impossible to obtain a high vacuum state without deteriorating the performance of the vacuum pump used in the vacuum system of the film deposition equipment. It was something that brought about this. Furthermore, when oil is used to remove dust, there is another problem in that the oil component flows into the vacuum chamber and has an undesirable effect on the film forming apparatus.

Furthermore, the ultrafine particles are sucked into the vacuum pump along with the gas, resulting in poor collection performance.

[Problem to be solved by the invention]

In order to solve the above-mentioned problems and technical problems of the prior art, Japanese Patent Laid-Open No. 63-264118 discloses a method that includes an inflow pipe connected to a vacuum chamber and an outflow pipe connected to a vacuum pump. The container is composed of double cylinders extending in the vertical direction, with a flow path for gas flowing between the double cylinders, one of the double cylinders serving as a high-temperature wall, and the other cylinder serving as a high-temperature wall. In addition to having low-temperature walls, the cross-sectional area and length of the double cylinder are maintained at an appropriate level to reduce the pressure difference required to pass through the container and to collect all the fine particles in the gas. proposed a device that

However, with the structure proposed above, the device must be disassembled each time to remove or recover the collected particles, and maintenance is very troublesome because the device is vertical.

Therefore, the present invention uses a vacuum pump that can sufficiently collect particulates such as dust in low-pressure gas without increasing the pressure difference, has a simple structure, is easy to manufacture, and can obtain a relatively high degree of vacuum. The object of the present invention is to provide a particulate trap for a vacuum exhaust system that is easy to maintain and can be maintained without disassembly.

[Means to solve the problem]

In order to achieve the above object, the particulate trub for vacuum pumping systems of the present invention includes a container connected to an inflow pipe connected to a vacuum chamber and an outflow pipe connected to a vacuum pump, respectively.
It is made up of double cylinders, a flow path for gas is formed between the double cylinders, one cylinder of the double cylinder is heated to a high temperature, and the other cylinder is used as a low temperature wall to form an elliptical structure. A fluid injection nozzle for injecting fluid toward the surface of the cylinder forming the low temperature is provided along the surface of the cylinder forming the high temperature wall, the fluid injection nozzle is connected to a fluid supply device, and the fluid injection nozzle is connected to the fluid injection nozzle. It is characterized in that the container is equipped with a device for discharging and collecting the fluid that is injected and the particles that accumulate in the container.

[For production]

Since the present invention is configured as described above, the inflow pipe is connected to, for example, a vacuum chamber of a film forming apparatus, the outflow pipe is connected to a vacuum pump capable of forming a low vacuum or medium vacuum, and the vacuum pump is activated. When activated, the gas in the vacuum chamber is sucked into the vacuum pump through the flow path between the double cylinders, but this flow path is formed with a hot wall and a cold wall facing each other. Fine particles such as dust in the gas sucked by a vacuum pump are developed by thermophoresis from the high temperature side to the low temperature side in a flow path formed by a double cylinder with a temperature gradient between high temperature walls and low temperature walls. It moves at high speed and attaches to the cold wall. The lower the pressure, the smaller the temperature gradient and the same speed of movement of these particles. Therefore, if the distance between the high-temperature wall and the low-temperature wall is increased to reduce the temperature gradient, that is, the cross-sectional area of the flow path is increased. Even in such cases, fine particles in the gas can be sufficiently adsorbed to the cold wall and collected.

Additionally, if the cross-sectional area of the flow path is made larger than the cross-sectional area of the inflow pipe, the pressure difference required to collect particulates will be small, so it can be installed on the suction side of a vacuum pump that can obtain a relatively high degree of vacuum. Therefore, it becomes possible to lower the pressure inside the vacuum chamber as much as possible.

Additionally, if a certain amount of particles accumulate inside this device, it will be necessary to perform cleaning (maintenance). Introducing fluid to the injection nozzle. The fluid is ejected in a jet form from a fluid ejection nozzle to peel off fine particles adhering to the cold wall.

When the pressure within the device reaches atmospheric pressure or higher, the fluid and particulate discharge and collection device is activated, allowing the particulates to be discharged and collected from the device.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a particulate trap according to an embodiment of the present invention in a longitudinal cross-sectional view. In FIG. It consists of a cylindrical body 2 and an inner cylindrical body 3, and a flow path 4 is formed between these cylindrical bodies 2.3. The opening near one end of the outer cylinder 2 is airtightly connected to an inlet pipe 6 via a vacuum flange 5, and this inlet pipe 6 is connected via a valve 7 to a vacuum chamber 8 of an acid film device or the like. The opening near the other end of the outer cylinder 2 is airtightly connected to an outflow pipe 10 via a vacuum 7 flange 9, and this outflow pipe 10 is connected to a vacuum pump such as a mechanical booster pump via a valve 12. It is connected to the pump 11. Further, the cross-sectional area of the flow path 4 between the cylinders 2.3 is larger than that of the inlet g6.

A heating heater 13 is attached to the outside of the outer cylindrical body 2, and this heating heater 13 measures the temperature with a thermocouple or the like (not shown) so that the temperature of the outer cylindrical body 2 can be controlled. Therefore, the outer cylinder 2 functions as a high temperature. Moreover, inside the inner cylinder 3, there is a film at one end of the container 1.
Cooling water is introduced and led out through cooling water pipes 14.15 for inflow and outflow provided through the inner cylinder 3, and maintains the inner cylinder 3 at a low temperature. 3 to function as a low temperature.

Further, a fluid supply path 16 is provided that passes through the fila at one end of the container 1 and supplies a fluid such as nitrogen gas during maintenance (cleaning). The (II!!'R+) of the fluid supply path 16 is connected to one fluid supply section via a valve 18.

A conduit 2° is provided that penetrates the filb at the other end of the container 1 to discharge and collect the fluid and particles accumulated in the container 1. It is connected to the recovery section 22.

This collection section 22 uses a simple scrubber or a bubbler that simply stores water, so that only fine particles can be collected.

Also rt of container 1! The lid 1b of 1f4A is equipped with a pressure sensor 2 that detects the pressure inside the container 1 and controls the operation of the valve 21.
3 is provided so that the valve 21 can be opened only when the pressure inside the container 1 is equal to or higher than atmospheric pressure.

Note that 24 is a bypass that bypasses the cylindrical container 1 and directly connects the vacuum chamber 7 and the vacuum pump 12;
4 is provided with valves 25,26.

The operation of the illustrated apparatus configured in this way will be described below.

When the vacuum pump 12 is operated with the valves 25 and 26 of the bypass 24 directly connecting the vacuum chamber 8 and the vacuum pump 12 closed, gas flows from the vacuum chamber 8 connected to the inflow pipe 6 to the inflow pipe 6 and the vacuum pump 12 . It flows through the flow path 4 in the double cylindrical container 1 to the outflow pipe 10 and is sucked into the vacuum pump 12. The flow path 4 includes an outer cylindrical body 2 maintained at a high temperature of, for example, 120°C;
Since it is defined between the inner cylinder 3 maintained at a low temperature of 0°C, the gas flowing through the flow path 4 has a temperature gradient perpendicular to the outer cylinder 2 and the inner cylinder 3. As a result, the fine particles in the gas move by thermophoresis at a speed from the high-temperature outer cylinder 2 side to the low-temperature inner cylinder 3 side, and adhere to the wall surface of the low-temperature inner cylinder 3. do. In this case, the lower the pressure in the flow path 4, the more the particles move at the same speed even if the temperature gradient is small. Therefore, a hot outer cylinder 2 and a cold inner cylinder 3 are used to collect particulates from the gas flowing at low pressure.
The distance between the two can be made as large as possible. This, together with the fact that the radius of the outer cylindrical body 2 can be set freely, makes it possible to arbitrarily make the cross-sectional area of the flow path 4 larger than that of the inlet pipe 6.

Therefore, the pressure difference required to flow the gas through the channel 4 becomes sufficiently small, so that not only a vacuum pump for low vacuum but also a vacuum pump capable of obtaining a relatively high degree of vacuum can be used. Moreover, since the performance of these vacuum pumps can be fully utilized, the pressure in the vacuum chamber 8 can be made to a relatively high degree of vacuum.

On the other hand, when the vacuum pump 12 is frequently operated and stopped, the valves 7.11 of the inflow pipe 6 and the outflow pipe 10 are closed, and the valve 25.26 of the bypass 24 is opened to allow gas to bypass the flow path 4. By flowing in this way, it is possible to prevent the particles collected from inside the container 1 from rising up and flowing out due to pressure fluctuations caused by the operation and stop of the vacuum pump.

The dimensions of the container 1 in the above example are changed depending on the gas flow rate, but include N 2 200scc11 (cc/5in at standard pressure), o25oscc+m, 5i2H
a 5 SCCIm.

Plasma CV flowed at a pressure of 0.3 TOrr in the film forming equipment
As a result of applying the device shown in FIG. 1 to the D device, when the device is not used, the vacuum pump 12 becomes clogged due to the reaction product (Sin2) and stops evacuation after about 10 minutes. Although the pressure rose to 10 TOrr, there was no fluctuation in pressure and the vacuum pump was not clogged while the above device was being used.

During cleaning, the valve 7 is closed, and in a vacuum state, the valve 18 of the fluid supply path 16 is opened to introduce nitrogen, and the jet-shaped gas is ejected from the fluid injection nozzle 17 toward the low-temperature wall so that the gas adheres thereto. Peel off the fine particles that are present.

When the pressure sensor 23 confirms that the pressure inside the container 1 has become equal to or higher than atmospheric pressure, the valve 21 is opened.

Nitrogen and fine particles flow from inside the container 1 to the collection section 22, and only the fine particles are collected at 22. During this time, nitrogen is in continuous flow.

FIG. 2 is an explanatory cross-sectional view showing another embodiment of the present invention, and in FIG. 1, the same reference numerals as those shown in FIG. 1 indicate the same or similar parts.

In this embodiment, the cooling water pipe 27 is wound around the outside of the outer cylinder 2 of the double cylindrical container l, and the heater 28 is built inside the inner cylinder 3, as described above. This is different from the embodiment (FIG. 1).

According to this embodiment, when the vacuum pump is operated, fine particles in the container 1 are thermophoretically migrated toward the inner surface of the outer cylinder 2, which is kept at a lower temperature, than the inner cylinder 3, which is kept at a higher temperature. It adheres to the inner wall of the outward cylinder 2.

Operations such as cleaning after the operation is stopped are the same as in the case of FIG. 1.

Incidentally, in each of the above-mentioned embodiments, the case where this trap is used in a film forming apparatus was explained, but when applied to an ultrafine particle production apparatus, the inflow pipe 6 is connected to a vacuum chamber where ultrafine particles are generated, and the outflow The tube 10 may be connected to a vacuum pump.

In addition, the heating means for the high temperature wall may be arbitrary, such as covering the high temperature with a block heater or burying the heater.Also, on the high temperature side, a heat insulating material may be attached to the outside to prevent heat radiation. I can do it.

On the other hand, the cooling means for the low-temperature wall may be arbitrary, and instead of the Jaguette type in the first embodiment, a cooling water pipe may be wrapped around it as in the second embodiment. Room temperature may be used without cooling. In this case, the high temperature wall side is controlled to maintain a predetermined temperature difference.

Further, when the present invention is implemented in a system using a gas that is not dangerous even when heated, the high temperature side may be set to room temperature, and the low temperature side may be cooled with liquid nitrogen or the like.

The double cylinder constituting the container of the trap according to the present invention is most preferably a cylinder, but it can also be formed of a polygonal cylinder or the like.

When the present invention is applied to a plasma CVD apparatus, fine particles generated by plasma CVD are unnecessary, so a scrubber can be used for collection.

Of course, it is also possible to use a liquid such as water or alcohol instead of gas, and perform cleaning with a liquid jet.

〔Effect of the invention〕

As explained above, according to the present invention, the container connected to the inflow pipe connected to the vacuum chamber and the outflow pipe connected to the vacuum pump is formed into a double cylindrical body consisting of a high-temperature wall and a low-temperature wall. A flow path is formed between these cylindrical bodies,
Since the structure is such that particles adhering to the low-temperature wall are scraped off by a fluid jet, the device can be easily cleaned and the particles can be discharged and collected without disassembling the device.

[Brief explanation of drawings]

FIG. 1 is a schematic partial vertical cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a schematic partial vertical cross-sectional view showing another embodiment of the present invention. In the figure 1... Container, 2... Outer cylinder, 3... Inner cylinder,
4... Channel, 5... Vacuum flange, 6... Inflow pipe, 7... Valve, 8... Vacuum chamber, 9... Vacuum flange, 10... Outflow pipe, 11. ...Valve, 12...
・Vacuum pump, 13...Heating heater, 14.15・
...Cooling water pipe, 16...Driftwood supply path, 17...
Fluid injection nozzle, 18... Valve, 19... Fluid supply section, 20... Pipeline, 21... Valve, 22...
Discharge and recovery section, 23...Pressure sensor, 24...Bypass, 25.26...Valve, 27...Cooling water pipe, 28...Heating heater. Figure 1

Claims (1)

[Claims] The containers connected to the inflow pipe connected to the vacuum chamber and the outflow pipe connected to the vacuum pump are constructed of double cylinders, and a flow path for gas is formed between the double cylinders. One cylinder of the heavy cylinder is configured as a high-temperature wall and the other cylinder is a low-temperature wall, and a fluid injection nozzle that injects fluid toward the surface of the cylinder forming the low-temperature wall is connected to the cylinder forming the high-temperature wall. and connecting the fluid injection nozzle to a fluid supply device;
Furthermore, a particle trap for a vacuum exhaust system, characterized in that the container is provided with a device for discharging and collecting the fluid ejected from the fluid injection nozzle and the particles accumulated in the container.